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  • 1
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    Inherited Grain‐Size Distributions: Effect on Heavy‐Mineral Assemblages in Modern and Ancient Sediments (2024)
    Details
    Publication Date: 2024-04-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Heavy‐mineral suites are used widely in sandstone provenance and are key when connecting source and sink. When characterizing provenance related signatures, it is essential to understand the different factors that may influence a particular heavy‐mineral assemblage for example, chemical weathering or diagenetic processes. Hydrodynamics, causing size‐density sorting, exert major control on the distribution of heavy minerals. Here, we highlight the effect of grain‐size inheritance, essentially the absence of certain grain sizes within a specific heavy‐mineral species, on two distinct types of sediments. Modern deposits from a high‐energy beach in NW Denmark give an analog for heavily reworked sediment, primarily controlled by hydrodynamic processes. In contrast, three Palaeogene turbidite successions in the Eastern Alps were sampled, presenting a more complex history that includes diagenesis. All samples were processed for their heavy‐mineral compositions using Raman spectroscopy, and several techniques applied to determine the effect of grain‐size inheritance. Results show that (a) even within the hydrodynamically well‐sorted beach and placer deposits, evidence of grain‐size inheritance is apparent, and (b) turbidites of variable heavy‐mineral composition show strong effects of grain‐size inheritance for several mineral species. Moreover, considerable intersample contrasts within single turbidite beds are observed. We enforce the importance of understanding grain‐size inheritance, as well as other processes effecting size‐density relations in clastic sediment that go well beyond purely hydrodynamic control of intrasample heavy‐mineral variability.〈/p〉
    Description: Plain Language Summary: Heavy minerals are commonly found within sediments and sedimentary rocks and can tell us from which source regions the sediment may have originated. However, it is important to understand that the type, size, and abundance of particular heavy minerals can change depending on factors such as environmental conditions. The size, shape, and density of the heavy minerals also limits when and where they will settle and/or stay. A lack of big or small grains of a particular heavy mineral in the source rocks dictates the size of the minerals deposited; this is known as grain‐size inheritance. Using both ancient and modern sediment, we are looking for traces of grain‐size inheritance. Surprisingly, in all samples investigated we noted effects of grain‐size inheritance, for different heavy‐mineral types. The modern beach sediments, as expected, show more impact of hydraulic processes, but inherited grain sizes are still apparent. Within the ancient examples, grain‐size inheritance is more obvious, with further variations even observed between samples collected from the same area. Having identified this control on grain size, we can highlight the importance of understanding this effect when analyzing clastic sediments.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Understanding factors that can modify a heavy‐mineral assemblage is fundamental in provenance analysis〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Heavy minerals of two distinct sedimentary environments were analyzed and compared to their “ideal” hydrodynamically sorted compositions〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Several heavy‐mineral species of modern and ancient settings were identified to be influenced by grain‐size inheritance from the source〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: https://doi.org/10.25625/MVUIJQ
    Keywords: ddc:552.5 ; heavy minerals ; provenance ; grain‐size inheritance ; hydrodynamics ; diagenesis
    Language: English
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  • 2
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    Geologic History of Deuteronilus Cavus in the Ismenius Lacus Region, Mars (2024)
    Details
    Publication Date: 2024-04-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Ismenius Lacus region of Mars has a diverse geological history, and we present the first high‐resolution map of Deuteronilus Cavus (36.2°N; 14.0°E, ∼120 km diameter) in the fretted terrain south of the dichotomy boundary. Strong evidence suggests a volcanic origin of the regional plains, based on the ∼50 m thick volcanic bed underlying 180–300 m of sublimation residue associated with Amazonian plateau glaciation. Pervasive external volcanic flooding, internal erosional modification, and enlargement of a pre‐existing crater by up to 175%–200% resulted in the cavus' present shape. The phyllosilicates detected within Deuteronilus Cavus could be primary materials associated with the surficial aqueous activity, subsurface alteration products excavated by impacts, or a combination of both. We observe branching fluvial channels that are more recent than the traditional valley networks and may be related to fretted terrain resurfacing during the waning period of a high‐obliquity glaciation phase. This is consistent with our interpretation of the ∼600 m thick lobate and lineated deposits, which are remnants of receding glaciers. The glacial ice, protected by a 15–20 m insulating layer of debris cover, is of significant interest for future landing missions because of its potential to preserve biological and climatological signatures, to provide a critical test of Amazonian plateau glaciation, and to be used for in situ resource utilization. With our detailed geological mapping, we improved our understanding of the geological evolution and climatic conditions in the enigmatic fretted terrain near the dichotomy boundary.〈/p〉
    Description: Plain Language Summary: The ∼120 km long Deuteronilus Cavus was initiated by an impact event. The resulting impact crater was modified by glacial erosional and fluvial processes, leading to the enlargement of 175%–200% of the pre‐existing crater. In addition, we find strong evidence for recent glaciation (〈1 Ga) that left 180–300 m of sublimation residue on the plateau superimposed on a ∼50 m thick volcanic bed, suggesting a volcanic origin of the regional plains. During the waning period of a high‐glacial phase, the meltwater ponded on the surface of the cavus, altered surface rocks to produce phyllosilicates, formed channels (now observed as inverted sinuous ridges), and locally distributed branched fluvial channels that are more recent than the traditional valley networks. Glacial landforms still contain up to 600 m of remnant ice from the retreating glaciers at the end of the last glacial period. The relatively pure ice, protected by a 15–20 m insulating layer of debris cover, is critical for future landing missions because of its potential to preserve biological and climatological signatures and to be used for in situ resource utilization. Overall, this research enhances our understanding of the geological evolution and climatic history of Mars.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We have produced the first high‐resolution map of Deuteronilus Cavus in the fretted terrain south of the Martian dichotomy boundary〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The region records a complex erosional and depositional history, including fluvial and glacial processes in the Amazonian period〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉This study provides a framework for exploration of high‐obliquity mid‐latitude plateau glaciation〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsches Zentrum für Luft‐ und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: https://doi.org/10.5281/zenodo.8205276
    Description: https://doi.org/10.17189/1520332
    Description: https://doi.org/10.17189/1520266
    Description: https://doi.org/10.17189/1520303
    Description: https://doi.org/10.5270/esa-pm8ptbq
    Keywords: ddc:523 ; Mars ; Deuteronilus Cavus ; geological mapping ; glaciation
    Language: English
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  • 3
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    Revised Magnetospheric Model Reveals Signatures of Field‐Aligned Current Systems at Mercury (2024)
    Details
    Publication Date: 2024-04-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Mercury is the smallest and innermost planet of our solar system and has a dipole‐dominated internal magnetic field that is relatively weak, very axisymmetric and significantly offset toward north. Through the interaction with the solar wind, a magnetosphere is created. Compared to the magnetosphere of Earth, Mercury's magnetosphere is smaller and more dynamic. To understand the magnetospheric structures and processes we use in situ MESSENGER data to develop further a semi‐empiric model of the magnetospheric magnetic field, which can explain the observations and help to improve the mission planning for the BepiColombo mission en‐route to Mercury. We present this semi‐empiric KTH22‐model, a modular model to calculate the magnetic field inside the Hermean magnetosphere. Korth et al. (2015, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/2015JA021022"〉https://doi.org/10.1002/2015JA021022〈/ext-link〉, 2017, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/2017gl074699"〉https://doi.org/10.1002/2017gl074699〈/ext-link〉) published a model, which is the basis for the KTH22‐model. In this new version, the representation of the neutral sheet current magnetic field is more realistic, because it is now based on observations rather than ad‐hoc assumptions. Furthermore, a new module is added to depict the eastward ring shaped current magnetic field. These enhancements offer the possibility to improve the main field determination. In addition, analyzing the magnetic field residuals allows us to investigate the field‐aligned currents and their possible dependencies on external drivers. We see increasing currents under more disturbed conditions inside the magnetosphere, but no clear dependence on the z‐component of the interplanetary magnetic field nor on the magnetosheath plasma 〈italic〉β〈/italic〉.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We present a revised model of Mercury's magnetospheric magnetic field〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The model now includes an eastward ring shaped current and the neutral sheet current is calculated more precisely with Biot Savart's law〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The strength of the field‐aligned currents increases with higher magnetic activity〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: German Ministerium für Wirtschaft und Klimaschutz and the German Zentrum für Luft‐ und Raumfahrt
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: ESA Research Fellowship
    Keywords: ddc:523 ; Mercury ; magnetosphere ; field‐aligned currents ; modeling ; neutral sheet current ; planetary dipole moment
    Language: English
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  • 4
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    Detecting Cold Pool Family Trees in Convection Resolving Simulations (2024)
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    Publication Date: 2024-04-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Recent observations and modeling increasingly reveal the key role of cold pools in organizing the convective cloud field. Several methods for detecting cold pools in simulations exist, but are usually based on buoyancy fields and fall short of reliably identifying the active gust front. The current cold pool (CP) detection and tracking algorithm (CoolDeTA), aims to identify cold pools and follow them in time, thereby distinguishing their active gust fronts and the “offspring” rain cells generated nearby. To accomplish these tasks, CoolDeTA utilizes a combination of thermodynamic and dynamical variables and examines the spatial and temporal relationships between cold pools and rain events. We demonstrate that CoolDeTA can reconstruct CP family trees. Using CoolDeTA we can contrast radiative convective equilibrium (RCE) and diurnal cycle CP dynamics, as well as cases with vertical wind shear and without. We show that the results obtained are consistent with a conceptual model where CP triggering of children rain cells follows a simple birth rate, proportional to a CP's gust front length. The proportionality factor depends on the ambient atmospheric stability and is lower for RCE, in line with marginal stability as traditionally ascribed to the moist adiabat. In the diurnal case, where ambient stability is lower, the birth rate thus becomes substantially higher, in line with periodic insolation forcing—resulting in essentially run‐away mesoscale excitations generated by a single parent rain cell and its CP.〈/p〉
    Description: Plain Language Summary: Cold pools are cooled air masses below thunderstorm clouds, produced when rain evaporates underneath such clouds. Cold pools are important, as they produce strong gusts and have been associated with clumping of rain cells, whereby heavy rainfall over relatively small areas could be generated—with implications for flooding. The current work describes a method that helps identify such cold pools in computer simulation data. In contrast to earlier methods, we here show that the interaction between a CP and its surroundings can be reconstructed by the method. We show that this identification works under a range of contexts, such as when horizontal wind is applied in the simulations or when the surface temperature is not constant—as might often be the case over a land surface. The identification reveals interesting dynamical effects, such as that in some cases, cold pools can kick‐start a form of chain reaction, by which “rain cell children” of it give rise to additional cold pools that again produce children, and so forth. The dynamics revealed is in line with expectations of widespread, so‐called mesoscale convective systems over land, whereas over an ocean surface the dynamics is much less explosive.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Our CoolDeTA algorithm reliably detects and tracks cold pools and their causal chains〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉We propose a simple conceptual model which reproduces the cascade‐like mesoscale cold pool dynamics identified by CoolDeTA〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉CoolDeTA opens for new studies into the dynamics of convective self‐organization through cold pools〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Villum Fonden http://dx.doi.org/10.13039/100008398
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: Novo Nordisk Foundation Interdisciplinary Synergy Program
    Description: Scientific Steering Committee
    Description: https://doi.org/10.5281/zenodo.6513224
    Description: https://github.com/Shakiro7/coldPool-detection-and-tracking
    Description: https://doi.org/10.5281/zenodo.10115957
    Description: https://doi.org/10.7717/peerj.453
    Keywords: ddc:551.6 ; cold pools ; detection ; tracking ; cloud resolving simulation ; convective organization
    Language: English
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  • 5
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    Thickness of the Seasonal Deposits at the Martian North Polar Region From Shadow Variations of Fallen Ice Blocks (2024)
    Details
    Publication Date: 2024-04-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The seasonal deposition and sublimation of CO〈sub〉2〈/sub〉 constitute a major element in the Martian volatile cycle. Here, we propose to use the shadow variations of the ice blocks at the foot of the steep scarps of the North Polar Layered Deposits (NPLD) to infer the vertical evolution of the seasonal deposits. We conduct an experiment at a steep scarp centered at (85.0°N, 151.5°E). We assume that no snowfall remains on top of the selected ice blocks, the frost ice layer is homogeneous around the ice blocks and their surroundings, and no significant moating is present. We show that the average thickness of the seasonal deposits due to snowfalls in Mars Year 31 is 0.97 ± 0.13 m at Ls = 350.7° in late winter. The large depth measured makes us wonder if snowfalls are more frequent and violent than previously thought. Meanwhile, we show that the average frost thickness in Mars Year 31 reaches 0.64 ± 0.18 m at Ls = 350.7° in late winter. Combined, the total thickness of the seasonal cover in Mars Year 31 reaches 1.63 ± 0.22 m at Ls = 350.7° in late winter, continuously decreases to 0.45 ± 0.06 m at Ls = 42.8° in middle spring and 0.06 ± 0.05 m at Ls = 69.6° in late spring. These estimates are up to 0.8 m lower than the existing Mars Orbiter Laser Altimeter results during the spring. Meanwhile, we observe that snow in the very early spring of Mars Year 36 can be 0.36 ± 0.13 m thicker than that in Mars Year 31. This study demonstrates the dynamics of the Martian climate and emphasizes the importance of its long‐term monitoring.〈/p〉
    Description: Plain Language Summary: Like Earth, Mars also has seasons. Up to one third of the atmospheric CO〈sub〉2〈/sub〉 annually exchanges with the polar surface through seasonal deposition/sublimation processes. Deposition can be either atmospheric precipitation as snowfall or direct surface condensation as frost. At the steep scarps of the North Polar Layered Deposits (NPLD), fractured ice fragments can detach and fall to form ice blocks. We propose to use variations in the shadows of these ice blocks, observed in the High Resolution Imaging Science Experiment images, to infer the thickness evolution of the seasonal deposits. We make reasonable assumptions about the distribution of snowfall and frost around the ice blocks and their surroundings, which allow us to separately measure the thickness of snowfall and frost. Meanwhile, we introduce a novel approach that allows us to estimate the thickness of the seasonal deposits during late winter and early spring when image quality is insufficient. This approach also enables us to peer into the interannual thickness variations of snowfall. We carry out a successful experiment at a scarp centered at (85.0°N, 151.5°E). The obtained thickness measurements demonstrate the dynamics of the Martian volatile cycling and can be used to constrain the Martian climate models.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We propose to examine the shadow variations of the ice blocks at the Martian polar region to infer the thickness of the seasonal deposits〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Maximum thickness of the seasonal deposits at the study scarp in MY31 is 1.63 ± 0.22 m to which snowfalls contribute 0.97 ± 0.13 m〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Seasonal deposits at the study scarp are up to 0.8 m shallower than previous measurements during spring〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: HX, LML, and PJG
    Description: https://doi.org/10.17189/1520303
    Description: https://doi.org/10.17632/5yy475dbry.1
    Description: https://doi.org/10.17632/x953mzxxvv.1
    Description: https://doi.org/10.17189/1520101
    Description: http://www.msss.com/moc_gallery/2001
    Keywords: ddc:523 ; Mars ; seasonal polar caps ; thickness ; ice blocks ; HiRISE ; CO2
    Language: English
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  • 6
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    INSIGHT: in situ heuristic tool for the efficient reduction of grazing‐incidence X‐ray scattering data (2024)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2024-04-25
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉〈italic〉INSIGHT〈/italic〉 is a Python‐based software tool for processing and reducing 2D grazing‐incidence wide‐ and small‐angle X‐ray scattering (GIWAXS/GISAXS) data. It offers the geometric transformation of the 2D GIWAXS/GISAXS detector image to reciprocal space, including vectorized and parallelized pixel‐wise intensity correction calculations. An explicit focus on efficient data management and batch processing enables full control of large time‐resolved synchrotron and laboratory data sets for a detailed analysis of kinetic GIWAXS/GISAXS studies of thin films. It processes data acquired with arbitrarily rotated detectors and performs vertical, horizontal, azimuthal and radial cuts in reciprocal space. It further allows crystallographic indexing and GIWAXS pattern simulation, and provides various plotting and export functionalities. Customized scripting offers a one‐step solution to reduce, process, analyze and export findings of large 〈italic〉in situ〈/italic〉 and 〈italic〉operando〈/italic〉 data sets.〈/p〉
    Keywords: ddc:548 ; grazing‐incidence X‐ray scattering ; time‐resolved studies ; in situ studies ; operando studies ; computer programs
    Language: English
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  • 7
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    Changes in Atmospheric Dynamics Over Dansgaard‐Oeschger Climate Oscillations Around 40 ka and Their Impact on Europe (2024)
    Details
    Publication Date: 2024-04-25
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Dansgaard‐Oeschger (D‐O) climate variability during the last glaciation was first evidenced in ice cores and marine sediments, and is also recorded in various terrestrial paleoclimate archives in Europe. The relative synchronicity across Greenland, the North Atlantic and Europe implies a tight and fast coupling between those regions, most probably effectuated by an atmospheric transmission mechanism. In this study, we investigated the atmospheric changes during Greenland interstadial (GI) and stadial (GS) phases based on regional climate model simulations using two specific periods, GI‐10 and GS‐9 both around 40 ka, as boundary conditions. Our simulations accurately capture the changes in temperature and precipitation as reconstructed by the available proxy data. Moreover, the simulations depict an intensified and southward shifted eddy‐driven jet during the stadial period. Ultimately, this affects the near‐surface circulation toward more southwesterly and cyclonic flow in western Europe during the stadial period, explaining much of the seasonal climate variability recorded by the proxy data, including oxygen isotopes, at the considered proxy sites.〈/p〉
    Description: Plain Language Summary: The climate during the last ice age varied between colder and warmer periods on timescales ranging from hundreds to thousands of years. This variability was first detected in Greenland ice cores and marine sediment cores of the North Atlantic, as well as in continental geological records in Europe. The variation between the colder and warmer periods occur mostly simultaneously in Greenland and in Europe, which is why the atmosphere is assumed to have an important role in transferring the climate signals. We simulated two different periods of the last ice age, one colder and one warmer around 40,000 years ago, using a regional climate model. The aim was to study how the climate and atmospheric circulation changed during these two periods. We find the eddy‐driven jet over the North Atlantic intensified and shifted southward during the colder period. The jet influences the near‐surface atmospheric circulation and leads to more southwesterly and cyclonic flow in western Europe. Oxygen isotope variations observed in western European paleoclimate records may be partly explained by different, more southern moisture sources on top of changes in seasonal temperatures.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Simulated temperatures agree with proxy data; precipitation is biased but GI‐10 versus GS‐9 differences are well captured〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The stadial winter jet stream is intensified and shifted southward, consistent with dominant southwesterly/cyclonic flow in western Europe〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Oxygen isotope signal changes at western European proxy sites may be explained not only by temperature but also by varying moisture sources〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: NRDIO
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: https://doi.org/10.5065/1dfh-6p97
    Keywords: ddc:551.6 ; Dansgaard‐Oeschger cycle ; regional atmospheric dynamics ; regional climate modeling ; continental paleoclimate proxy ; Europe
    Language: English
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  • 8
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    Energy‐dispersive X‐ray stress analysis under geometric constraints: exploiting the material's inherent anisotropy (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-09-12
    Description: Two data evaluation concepts for X‐ray stress analysis based on energy‐dispersive diffraction on polycrystalline materials with cubic crystal structure, almost random crystallographic texture and strong single‐crystal elastic anisotropy are subjected to comparative assessment. The aim is the study of the residual stress state in hard‐to‐reach measurement points, for which the sin2ψ method is not applicable due to beam shadowing at larger sample tilting. This makes the approaches attractive for stress analysis in engineering parts with complex shapes, for example. Both approaches are based on the assumption of a biaxial stress state within the irradiated sample volume. They exploit in different ways the elastic anisotropy of individual crystallites acting at the microscopic scale and the anisotropy imposed on the material by the near‐surface stress state at the macroscopic scale. They therefore complement each other, in terms of both their preconditions and their results. The first approach is based on the evaluation of strain differences, which makes it less sensitive to variations in the strain‐free lattice parameter a0. Since it assumes a homogeneous stress state within the irradiated sample volume, it provides an average value of the in‐plane stresses. The second approach exploits the sensitivity of the lattice strain to changes in a0. Consequently, it assumes a homogeneous chemical composition but provides a stress profile within the information depth. Experimental examples from different fields in materials science, namely shot peening of austenitic steel and in situ stress analysis during welding, are presented to demonstrate the suitability of the proposed methods.
    Description: The single‐crystal elastic anisotropy and the anisotropy of the near‐surface (residual) stress state of polycrystalline materials with random texture are exploited in energy‐dispersive X‐ray stress analysis to study samples under constrained measurement conditions.
    Keywords: ddc:548 ; X‐ray stress analysis ; energy‐dispersive diffraction ; polycrystalline materials ; single‐crystal elastic anisotropy
    Language: English
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  • 9
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    Decompression and Fracturing Caused by Magmatically Induced Thermal Stresses (2023)
    Details
    Publication Date: 2023-09-12
    Description: Studies of host rock deformation around magmatic intrusions usually focus on the development of stresses directly related to the intrusion process. This is done either by considering an inflating region that represents the intruding body, or by considering multiphase deformation. Thermal processes, especially volume changes caused by thermal expansion are typically ignored. We show that thermal stresses around upper crustal magma bodies are likely to be significant and sufficient to create an extensive fracture network around the magma body by brittle yielding. At the same time, cooling induces decompression within the intrusion, which can promote the appearance of a volatile phase. Volatile phases and the development of a fracture network around the inclusion may thus be the processes that control magmatic‐hydrothermal alteration around intrusions. This suggests that thermal stresses likely play an important role in the development of magmatic systems. To quantify the magnitude of thermal stresses around cooling intrusions, we present a fully compressible 2D visco‐elasto‐plastic thermo‐mechanical numerical model. We utilize a finite difference staggered grid discretization and a graphics processing unit based pseudo‐transient solver. First, we present purely thermo‐elastic solutions, then we include the effects of viscous relaxation and plastic yielding. The dominant deformation mechanism in our models is determined in a self‐consistent manner, by taking into account stress, pressure, and temperature conditions. Using experimentally determined flow laws, the resulting thermal stresses can be comparable to or even exceed the confining pressure. This suggests that thermal stresses alone could result in the development of a fracture network around magmatic bodies.
    Description: Plain Language Summary: Quantifying the stresses that magma bodies exert on the surrounding rocks is an important part of understanding mechanical processes that control the evolution of magmatic systems and volcanic eruptions. Previous analytical or numerical models typically describe the mechanical response to changes in magma volume due to intrusion or extraction of magma. However, volume changes related to thermal expansion/contraction around a cooling magma body are often neglected. Here, we develop a new software which runs on modern graphics processing unit machines, to quantity the effect of this process. The results show that stresses due to thermal expansion/contraction are significant, and often large enough to fracture the rocks nearby the magma body. Such fracture networks may form permeable pathways for the magma or for fluids such as water and CO〈sub〉2〈/sub〉, thus influencing the evolution of magmatic and hydrothermal systems. Finally we show that cooling and shrinking of magma bodies causes significant decompression which can influence the chemical evolution of the magma during crystallization and devolatilization.
    Description: Key Points: We present a numerical quantification of the effect of thermal stresses in visco‐elasto‐plastic rock with tensile and dilatant shear failure. The pressure drop in thermally contracting upper crustal magma bodies can exceed 100 MPa, potentially triggering devolatilization. Thermal cracking can create an extensive fracture network around an upper crustal magma body.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: https://zenodo.org/record/6958273
    Description: https://doi.org/10.5281/zenodo.6958273
    Keywords: ddc:551.8 ; magmatic intrusions ; host rock deformation ; thermal stress ; numerical quantification
    Language: English
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  • 10
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    Triple‐Element Stable Isotope Analysis of Chloromethane Emitted by Royal Fern and Degraded by Club Moss (2023)
    Details
    Publication Date: 2023-09-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Chloromethane (CH〈sub〉3〈/sub〉Cl) is the most abundant natural chlorinated organic compound in the atmosphere playing an important role in catalyzing stratospheric ozone loss. Vegetation emits the largest amounts of CH〈sub〉3〈/sub〉Cl to the atmosphere but its source strength is highly uncertain leading also to large uncertainties in the global budget of CH〈sub〉3〈/sub〉Cl. Triple‐element stable isotope analysis may help to reduce uncertainties because it provides additional process‐level information compared to conventional quantification methods. In this study we performed experiments to obtain a first triple‐elemental isotopic fingerprint (〈sup〉2〈/sup〉H, 〈sup〉13〈/sup〉C, 〈sup〉37〈/sup〉Cl) of CH〈sub〉3〈/sub〉Cl emitted by a relevant plant species (royal fern, 〈italic〉Osmunda regalis〈/italic〉). Isotopic values of all three elements showed considerable differences compared to isotopic values of industrially manufactured CH〈sub〉3〈/sub〉Cl which bodes well for future applications to distinguish individual sources. Isotopic analysis of potential precursors (rain, methoxy groups) of CH〈sub〉3〈/sub〉Cl in plants revealed no measurable change of hydrogen and chlorine isotopic ratios during formation which may provide a simpler route to estimate the isotopic composition of CH〈sub〉3〈/sub〉Cl emissions. Plant degradation experiments of CH〈sub〉3〈/sub〉Cl were carried out with club moss (〈italic〉Selaginella kraussiana〈/italic〉) revealing significant isotopic fractionation for all three elements. The fractionation pattern characterized by epsilon and lambda is inconsistent with known biotic dechlorination reactions indicating a yet unreported biotic degradation mechanism for CH〈sub〉3〈/sub〉Cl. Overall, this study provides first insights into the triple‐elemental isotopic fingerprint of plant emissions and degradation. The results may represent important input data for future isotope‐based models to improve global budget estimates of CH〈sub〉3〈/sub〉Cl and to explore the yet unknown degradation pathways.〈/p〉
    Description: Plain Language Summary: Chloromethane is the most abundant chlorinated organic compound in the atmosphere. It contributes to the destruction of the ozone layer that protects us from skin cancer and genetic damage. Currently, we do not have a good understanding of the sources and removal processes of chloromethane in the atmosphere. In this paper, we use a technique that takes advantage of the different varieties of a chemical element. These so‐called isotopes behave differently during chemical reactions that lead to individual isotopic fingerprints depending on the source or removal process. We used isotopic fingerprints of all three chemical elements in chloromethane and showed that chloromethane produced by a plant (royal fern) differs substantially from chloromethane manufactured by industry. Other plant species such as club moss are able to remove chloromethane from the atmosphere but it is often not clear how this occurs. Isotopic analysis revealed that the studied club moss uses a unique, thus far unknown, way to break down chloromethane. This study demonstrates how information extracted from isotopic fingerprints will help to improve our understanding of sources and removal processes of chloromethane in the atmosphere. It can help to better predict how ozone destruction in the stratosphere affects us in the future.〈/p〉
    Description: Key Points: First triple‐element isotopic characterization of plant CH〈sub〉3〈/sub〉Cl emission and degradation. Plant degradation experiments suggest another yet unknown transformation pathway. Important input data for future isotope based models to improve understanding of global CH〈sub〉3〈/sub〉Cl budget.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.48758/ufz.13388
    Keywords: ddc:551.9 ; CH3Cl ; ozone depletion ; isotopes ; plant emissions ; halogens
    Language: English
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  • 11
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    Seismotectonics of the Blanco Transform Fault System, Northeast Pacific: Evidence for an Immature Plate Boundary (2023)
    Details
    Publication Date: 2023-09-13
    Description: At the Blanco transform fault system (BTFS) off Oregon, 138 local earthquakes and 84 double‐couple focal mechanisms from ocean‐bottom‐seismometer recordings jointly discussed with bathymetric features reveal a highly segmented transform system without any prominent fracture zone traces longer than 100 km. In the west, seismicity is focused at deep troughs (i.e., the West and East Blanco, and Surveyor Depressions). In the east, the BTFS lacks a characteristic transform valley and instead developed the Blanco Ridge, which is the most seismically active feature, showing strike‐slip and dip‐slip faulting. Sandwiched between the two main segments of the BTFS is the Cascadia Depression, representing a short intra‐transform spreading segment. Seismic slip vectors reveal that stresses at the eastern BTFS are roughly in line with plate motion. In contrast, stresses to the west are clockwise skewed, indicating ongoing reorganization of the OTF system. As we observed no prominent fracture zones at the BTFS, plate tectonic reconstructions suggest that the BTFS developed from non‐transform offsets rather than pre‐existing transform faults during a series of ridge propagation events. Our observations suggest that the BTFS can be divided into two oceanic transform systems. The eastern BTFS is suggested to be a mature transform plate boundary since ∼0.6 Ma. In contrast, the western BTFS is an immature transform system, which is still evolving to accommodate far‐field stress change. The BTFS acts as a natural laboratory to yield processes governing the development of oceanic transform faults.
    Description: Plain Language Summary: The Blanco transform fault system (BTFS) northwest off the coast of Oregon is seismically very active. We used 1 year of ocean bottom seismometer data collected between September 2012 and October 2013 to locate 138 local earthquakes. The events align perfectly with the morphologic features of the BTFS, dividing the BTFS into five transform segments and two short intra‐transform spreading centers. Furthermore, we observe different seismotectonic behaviors of the western and eastern BTFS based on the along‐strike variation in morphology, magnetization, focal depth distribution, and strain partitioning. Although many segmented oceanic transform systems were formed from a single transform fault in response to rotations in plate motion, the BTFS turns out to be originated from non‐transform offsets between ridge segments, as we observed no prominent fracture zone traces neither in morphology nor gravity field data. A clockwise shift in the Juan de Fuca/Pacific pole of rotation at ∼5 Ma followed by a series of ridge propagation events initiated the formation of the BTFS, integrated each segment of the BTFS by shortening the ridge segments in between. Our observations suggest that the Blanco Ridge and the Gorda transform segment in the eastern BTFS were formed at ∼1.6 and 0.6 Ma, respectively, and ever since, the eastern BTFS became a mature transform boundary. In contrast, seismic slip vectors comparing to plate motion directions reveal that stresses in the western BTFS are systematically skewed, suggesting the immature transform plate boundary is still adjusting to the new stress regime.
    Description: Key Points: Local seismicity of the Blanco transform fault system (BTFS) reveals along‐strike variations dominated by strike‐slip and oblique dip‐slip. The BTFS developed from non‐transform offsets rather than discrete transform faults in response to plate rotation and ridge propagation. The BTFS consists of a mature plate boundary in the east and an immature system in the west, separated by a central spreading center.
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: https://doi.org/10.7914/SN/X9_2012
    Description: https://www.gmrt.org/GMRTMapTool/
    Description: https://mrdata.usgs.gov/magnetic/
    Keywords: ddc:551.22 ; Blanco transform fault system ; local seismicity ; tectonic evolution ; transform plate boundary
    Language: English
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  • 12
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    Magnetic Fields and Plasma Motions in a Hybrid Martian Magnetosphere (2023)
    Details
    Publication Date: 2023-09-13
    Description: The Martian magnetosphere contains elements of induced and intrinsic origin. To display them one must use different coordinate systems. Although the solar‐electric coordinate system (Mars Solar Electric [MSE]) adequately describes the main features of the induced magnetosphere, it removes/suppresses aspects caused by the crustal magnetic sources while rotating the spacecraft position to the MSE‐coordinate system and averaging over many orbits. On the other hand, to observe effects of the crustal field one should use the solar orbital coordinates (Mars Solar Orbital [MSO]). To find a compromise and keeping in mind that the most probable value of the clock angle of the interplanetary magnetic field (IMF) on the Mars orbit is ∼90° we can consider separately cases with positive and negative B〈sub〉y〈/sub〉 components of the IMF. It is shown that dynamics of ion fluxes in the distant regions of the magnetosphere is mainly controlled by induced features. However, reconnection of the draping IMF with crustal field leads to a twisting of the classical draping configuration. Despite of the very intricate local geometry of the crustal field, the low‐order harmonics of the magnetic field and mainly the dipole component determine the reconnection sites, at least, statistically for many Mars rotations. For different signs of the By component of the IMF these sites occur either in the +Y‐MSO or −Y‐MSO hemispheres. As a result, statistically the magnetosphere of Mars looks like a hybrid magnetosphere formed during the solar wind interaction with the obstacle which simultaneously contains an extended ionosphere and a weak dipole magnetic field.
    Description: Key Points: The Martian magnetosphere contains elements of induced and intrinsic origin. Dynamics of ion fluxes in the magnetic tail, is mainly controlled by induced features. Reconnection of the interplanetary magnetic field with low‐order harmonics of the crustal field leads to twisting of the tail and formation of hybrid magnetosphere.
    Description: DFG
    Description: https://pds-ppi.igpp.ucla.edu/mission/MAVEN
    Keywords: ddc:523 ; Martian magnetosphere
    Language: English
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    Atmospheric CO2 Concentration Based on Boron Isotopes Versus Simulations of the Global Carbon Cycle During the Plio‐Pleistocene (2023)
    Details
    Publication Date: 2023-09-13
    Description: Atmospheric carbon dioxide concentrations (pCO〈sub〉2〈/sub〉) beyond ice core records have been reconstructed from δ〈sup〉11〈/sup〉B derived from planktic foraminifera found in equatorial sediment cores. Here, I applied a carbon cycle model over the Plio‐Pleistocene to evaluate the assumptions leading to these numbers. During glacials times, simulated atmospheric pCO〈sub〉2〈/sub〉 was unequilibrated with pCO〈sub〉2〈/sub〉 in the equatorial surface ocean by up to 35 ppm while the δ〈sup〉11〈/sup〉B‐based approaches assume unchanged (quasi)equilibrium between both. In the Pliocene, δ〈sup〉11〈/sup〉B‐based estimates of surface ocean pH are lower in the Pacific than in the Atlantic resulting in higher calculated pCO〈sub〉2〈/sub〉. This offset in pH between ocean basins is not supported by models. To calculate pCO〈sub〉2〈/sub〉 in surface waters out of the δ〈sup〉11〈/sup〉B‐based pH some assumptions on either total alkalinity or dissolved inorganic carbon are necessary. However, the assumed values of these under‐constrained variables were according to my results partly inconsistent with chemically possible combinations within the marine carbonate system. The model results show glacial/interglacial variability in total alkalinity of the order of 100 μmol/kg, which is rarely applied to proxy reconstructions. Simulated atmospheric pCO〈sub〉2〈/sub〉 is tightly (r〈sup〉2〈/sup〉 〉 0.9) related to equatorial surface‐ocean pH, which can be used for consistency checks. Long‐term trends in volcanic CO〈sub〉2〈/sub〉 outgassing and the strength of the continental weathering fluxes are still unconstrained, allowing for a wide range of possible atmospheric pCO〈sub〉2〈/sub〉 across the Plio‐Pleistocene. Nevertheless, this carbon cycle analysis suggests that reported atmospheric pCO〈sub〉2〈/sub〉 above 500 ppm in the Pliocene might, for various reasons, need to be revised to smaller numbers.
    Description: Key Points: Simulated equatorial surface ocean 𝑝CO〈sub〉2〈/sub〉 is near‐equilibrium with atmosphere during interglacials but enriched (≤35 ppm) during glacials. Models suggest similar equatorial surface 𝑝H in Pacific and in Atlantic in high CO〈sub〉2〈/sub〉 worlds while Pliocene reconstructions show offsets. Carbon cycle model analysis suggests that reported CO〈sub〉2〈/sub〉 values above 500 ppm in the Pliocene might need revisions to smaller numbers.
    Keywords: ddc:551 ; carbon cycle ; modeling ; CO2 ; boron isotopes ; pH ; Plio‐Pleistocene
    Language: English
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  • 14
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    Temporal Variability of Fluvial Sand Composition: An Annual Time Series From Four Rivers in SW Germany (2023)
    Details
    Publication Date: 2023-09-13
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The sampling of fluvial sediment is subject to many sources of uncertainty, for example, time and location, and the number of samples collected. It is nevertheless commonly assumed that a sample taken at one time and location provides a somewhat averaged compositional signal. Any spatial or temporal variability of this signal is often neglected. This study investigates how the composition of bed load sand changes over an observation period of 1 year in four river basins with differing bedrock geology in southwestern Germany. Up to 12 bulk sediment samples were taken at the same locations using the same approach and analyzed for their granulometry and geochemistry. The results indicate that (a) different grain sizes yield different compositions due to source rock composition and hydraulic sorting effects, (b) bulk sediment composition changes temporally due to changing grain‐size distribution, and (c) compared to the bulk sample, the composition of narrow grain sizes is temporally more stable but nevertheless has an average variability of 15%. Because heavy mineral‐bound elements such as Zr have the highest variability, we relate a major component of compositional variability to temporally varying heavy mineral concentrations in response to hydrodynamic processes. Mixing modeling demonstrates that the fluvial sand faithfully reflects its catchment geology and that the sediment sources do not change substantially during the observation period, even during a flooding event. We conclude (a) that the causes for compositional variability may be disentangled using chemical and granulometric time series data and (b) that narrow grain sizes yield representative source rock contributions.〈/p〉
    Description: Plain Language Summary: Sediment transported by rivers is generated by the erosion of the rocks present within the river catchment area. The composition of this sediment is controlled by various processes in the catchment, for example, climate, rock type, weathering, and flow strength. Geoscientists can use modern river sediment to understand how these processes impact sediment composition, and then apply this information to the geologic time. Sampling the river sediment is often the first step in such studies, but few studies consider the sources of uncertainty during sampling, for example, time and location of sampling, and number of collected samples. For this study, we returned to the same river location during the course of 1 year to take bulk sediment samples and analyzed how variable the size of sediment grains and the sediment chemistry are. We discovered that different grain sizes yield different chemical compositions, and this is caused by differences in rock type and hydraulic processes. Because the proportion of different grain sizes in the bulk sediment changes over the year due to water flow conditions, the chemistry of the bulk sediment sample changes over the year. We provide some quantitative estimates for this variability that should be considered in similar studies.〈/p〉
    Description: Key Points: Bed load sand from 4 rivers was sampled monthly over the course of 1 year to analyze the temporal compositional variability. Composition is grain‐size‐dependent, and narrow grain‐size fractions show less variability than bulk sediment samples. Composition changes during the year, and this is related to changing grain‐size distributions rather than changing sediment sources.
    Description: https://doi.pangaea.de/10.1594/PANGAEA.959006
    Keywords: ddc:551.9 ; geochemistry ; provenance ; grain‐size ; variability ; bed load ; fluvial sediment
    Language: English
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    Promoting FAIR and open data publication at the Department of Earth Sciences, Freie Universität Berlin (2023)
    Details
    Publication Date: 2023-09-18
    Description: The Department of Earth Sciences at Freie Universität Berlin has recently established a concept and workflow for the promotion of research data and its publishing. The project, funded with seed money from central university administration, was developed in close cooperation with the research data management (RDM) team of the university library. A key element in the project is the RDM-team proactively advertising support for data publishing to researchers of the department. This offer is very well received by the researchers, as they are often willing to publish data, but lack time as well as knowledge of best practice in data publication. Several data publishing projects have been kicked-off this way. Another thrust of the project is to feature data publications on the department´s website. This fosters the recognition of data publications as important resarch output of the scientists of the Department of Earth Sciences. The data are presented on the website in an easily accessible and understandable context, to makes them available to potenially new user groups like lay persons, citizen scientists, or pupils. Before published on the website, researchers are asked by the RDM-team to proof-read short descriptive drafts about their data publications, and this opens up a great opportunity for researchers to engage with data publication specialists about best practices and standards of „FAIR and open“ data practices. This project facilitates cultural change towards FAIR and open data publication at an university department and may be used as a blueprint for departments in other universities and research institutions.
    Description: presentation
    Keywords: Research data ; FAIR principles ; Open science
    Language: English
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    On the Temperature Dependence of the Cloud Ice Particle Effective Radius—A Satellite Perspective (2023)
    Details
    Publication Date: 2023-12-05
    Description: Cloud ice particle effective radius in atmospheric models is usually parametrized. A widely‐used parametrization comprises a strong dependence on the temperature. Utilizing available satellite‐based estimates of both cloud ice particle effective radius and cloud‐top temperature we evaluate if a similar temperature‐dependence exists in these observations. We find that for very low cloud‐top temperatures the modeled cloud ice particle effective radius generally agrees on average with satellite observations. For high sub‐zero temperatures however, the modeled cloud ice particle effective radius becomes very large, which is not seen in the satellite observations. We conclude that the investigated parametrization for the cloud ice particle effective radius, and parametrizations with a similar temperature dependence, likely produce systematic biases at the cloud top. Supporting previous studies, our findings suggest that the vertical structure of clouds should be taken into account as factor in potential future updates of the parametrizations for cloud ice particle effective radius.
    Description: Plain Language Summary: Atmospheric models are often used to diagnose and predict the atmospheric state including clouds. One very important property of clouds that consist of ice particles is the cloud ice particle effective radius. This ice effective radius is based on assumptions about the size and shapes of the ice particles in clouds, and thus parametrized, and is one of the important variables needed for calculating the effect of clouds on electromagnetic radiation, in particular on the solar radiation that enters the Earth's atmosphere. In our study we found that the parametrized ice effective radius agrees well on average and global scale with the ice effective radius inferred from satellite observations for cold clouds. However, we also found that for warmer ice clouds the parametrized ice effective radius is much higher than in satellite observations. Our study suggests that parametrizations of the ice effective radius used in atmospheric models show potential for improvements.
    Description: Key Points: Comparisons of modeled cloud ice particle effective radius with satellite observations are presented. For very low cloud temperatures the modeled cloud ice particle effective radius agrees on average with satellite observations. Modeled large cloud ice particle effective radii for high sub‐zero temperatures are not found in satellite observations.
    Description: European Space Agency http://dx.doi.org/10.13039/501100000844
    Description: https://doi.org/10.5281/zenodo.7445152
    Description: https://doi.org/10.5676/DWD/ESA_Cloud_cci/AVHRR-PM/V003
    Description: https://doi.org/10.5676/EUM_SAF_CM/CLARA_AVHRR/V002
    Description: http://doi.org/10.5067/MODIS/MYD06_L2.NRT.061
    Keywords: ddc:551.5 ; clouds ; ice particle effective radius ; parametrization ; model ; satellite observations
    Language: English
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    Impact of Diurnal Warm Layers on Atmospheric Convection (2023)
    Details
    Publication Date: 2023-12-05
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This manuscript presents a study of oceanic diurnal warm layers (DWLs) in kilometer‐scale global coupled simulations and their impact on atmospheric convection in the tropics. With the implementation of thin vertical levels in the ocean, DWLs are directly resolved, and sea surface temperature (SST) fluctuations of up to several Kelvin appear in regions with low wind and high solar radiation. The increase of SST during the day causes an abrupt afternoon increase of atmospheric moisture due to enhanced latent heat flux (LHF), followed by an increase in cloud cover (CC) and cloud liquid water (CLW). However, although the diurnal SST amplitude is even exaggerated in comparison to reanalysis, this effect only lasts for 5–6 hr and leads to an absolute difference of 1% for CC and 0.01 kg m〈sup〉−2〈/sup〉 for CLW. This can be explained by the fact that the low wind over the SST anomalies dampens their potential effect on the LHF and hence clouds. All in all, the impact of DWLs on convective CC is found to be negligible in the tropical mean.〈/p〉
    Description: Plain Language Summary: The diurnal fluctuations of sea surface temperature (SST) have been extensively studied for the last decades, but the assessment of the importance of this phenomenon for atmospheric convection on the global scale has come within reach only very recently, thanks to the development of simulations with a horizontal resolution of O(1 km). In this manuscript we show that we can indeed observe an impact of SST fluctuations on moisture in the atmosphere. However, the impact on the amount of clouds in the tropics is found to be short‐lived and its magnitude negligible on average.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉diurnal warm layers (DWLs) increase atmospheric moisture〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The increase of cloud cover (CC) following the formation of a DWL is immediate and only lasts for several hours〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The magnitude of the CC increase is small and has no discernible influence on the global mean〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://gotm.net/
    Description: https://hdl.handle.net/21.11116/0000-000C-1447-E
    Keywords: ddc:551 ; diurnal warm layers (DWLs) ; atmospheric moisture ; cloud cover ; convection
    Language: English
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    Transboundary Rainfall Estimation Using Commercial Microwave Links (2023)
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    Publication Date: 2023-12-05
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Unlike actual rainfall, the spatial extent of rainfall maps is often determined by administrative and political boundaries. Similarly, data from commercial microwave links (CMLs) is usually acquired on a national basis and exchange among countries is limited. Up to now, this has prohibited the generation of transboundary CML‐based rainfall maps despite the great extension of networks across the world. We present CML based transboundary rainfall maps for the first time, using independent CML data sets from Germany and the Czech Republic. We show that straightforward algorithms used for quality control strongly reduce anomalies in the results. We find that, after quality control, CML‐based rainfall maps can be generated via joint and consistent processing, and that these maps allow to seamlessly visualize rainfall events traversing the German‐Czech border. This demonstrates that quality control represents a crucial step for large‐scale (e.g., continental) CML‐based rainfall estimation.〈/p〉
    Description: Plain Language Summary: Rainfall maps are usually based on gauge observations on the ground or radar. They are crucial for predicting or reconstructing flooding events. Commercial microwave links are special kinds of rainfall sensors. Their actual purpose is the signal propagation within a cellular network. However, since the signal is attenuated when it rains, they can also be exploited for rainfall estimation. To estimate rainfall from the observed attenuation requires careful data processing. Algorithms for that are usually adjusted to national data sets with their specific characteristics. In this study, we use, for the first time, two independent data sets of commercial microwave links (from Germany and the Czech Republic) with the aim of generating transboundary rainfall maps. As the data sets vary in many respects, several algorithms need to be adjusted and extended to allow processing them consistently. We show that it is possible to create meaningful rainfall maps of rain events that traverse the border between Germany and the Czech Republic. This can be considered a major step toward seamless rainfall maps on even larger, that is, continental scale.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Transboundary rainfall maps based on independent networks of commercial microwave links (CMLs) are generated for the first time〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉German and Czech data sets of CMLs differ significantly with respect to network characteristics〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Quality control is important for heterogeneous data of CMLs〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: German Research Foundation
    Description: Czech Science Foundation
    Description: https://doi.org/10.5281/zenodo.4810169
    Description: https://doi.org/10.5281/zenodo.7973736
    Description: https://opendata.dwd.de/climate_environment/CDC
    Keywords: ddc:551.6 ; transboundary rainfall maps ; commercial microwave links ; quantitative precipitation estimation ; data quality control
    Language: English
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    Missing Rainfall Extremes in Commercial Microwave Link Data Due To Complete Loss of Signal (2023)
    Details
    Publication Date: 2023-12-05
    Description: An important aspect of rainfall estimation is to accurately capture extreme events. Commercial microwave links (CMLs) can complement weather radar and rain gauge data by estimating path‐averaged rainfall intensities near ground. Our aim with this paper was to investigate attenuation induced complete loss of signal (blackout) in the CML data. This effect can occur during heavy rain events and leads to missing extreme values. We analyzed 3 years of attenuation data from 4,000 CMLs in Germany and compared it to a weather radar derived attenuation climatology covering 20 years. We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for longer CMLs (e.g., 〉10 km) despite their increased dynamic range. Therefore, both the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.
    Description: Plain Language Summary: Commercial microwave links (CMLs) are used to transmit information between towers of cellphone networks. If there is rainfall along the transmission path, the signal level is attenuated. By comparing the transmitted and received signal levels, the average rainfall intensity along the path can be estimated. If the attenuation is too strong, no signal is received, no information can be transmitted and no rainfall estimate is available. This is unfavorable both for network stability and rainfall estimation. In this study, we investigated the frequency of such blackouts in Germany. How many blackouts per year are observed in a 3 year CML data set covering around 4,000 link paths and how many are expected from 20 years of weather radar data? We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for long CMLs, which was an unexpected finding. While only one percent of the annual rainfall amount is missed during blackouts, the probability that a blackout occurs was very high for high rain rates. Both, the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.
    Description: Key Points: Complete loss of commercial microwave link (CML) signals during heavy rain leads to missing rainfall extremes. Magnitude of observed blackouts exceeds climatologically expected values. Unexpectedly, longer CMLs experience more blackouts.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Karlsruhe Institute of Technology http://dx.doi.org/10.13039/100009133
    Description: https://doi.org/10.5281/zenodo.7245440
    Description: https://github.com/pycomlink/pycomlink/blob/12fc302539851b19f7656cf7e2438c0ddbaa48bf/notebooks/Blackout%20gap%20detection%20examples.ipynb
    Description: https://doi.org/10.5281/zenodo.6337557
    Description: https://doi.org/10.5676/DWD/RADKLIM_YW_V2017.002
    Keywords: ddc:551.6 ; commercial microwave links ; rainfall ; opportunistic sensing ; weather radar ; rainfall extremes ; precipitation
    Language: English
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  • 20
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    Impact of Cyclonic Wind Anomalies Caused by Massive Winter Sea Ice Retreat in the Barents Sea on Atlantic Water Transport Toward the Arctic: A Model Study (2023)
    Details
    Publication Date: 2023-12-05
    Description: The Arctic is warming much faster than the global average. This is known as Arctic Amplification and is caused by feedbacks in the local climate system. In this study, we explore a previously proposed hypothesis that an associated wind feedback in the Barents Sea could play an important role by increasing the warm water inflow into the Barents Sea. We find that the strong recent decrease in Barents Sea winter sea ice cover causes enhanced ocean‐atmosphere heat flux and a local air temperature increase, thus a reduction in sea level pressure and a local cyclonic wind anomaly with eastward winds in the Barents Sea Opening. By investigating various reanalysis products and performing high‐resolution perturbation experiments with the ocean and sea ice model FESOM2.1, we studied the impact of cyclonic atmospheric circulation changes on the warm Atlantic Water import into the Arctic via the Barents Sea and Fram Strait. We found that the observed wind changes do not significantly affect the warm water transport into the Barents Sea, which rejects the wind‐feedback hypothesis. At the same time, the cyclonic wind anomalies in the Barents Sea increase the amount of Atlantic Water recirculating westwards in Fram Strait by a downslope shift of the West Spitsbergen Current, and thus reduce Atlantic Water reaching the Arctic basin via Fram Strait. The resulting warm‐water anomaly in the Greenland Sea Gyre drives a local anticyclonic circulation anomaly.
    Description: Plain Language Summary: The Barents Sea has been experiencing a rapid decrease in its winter sea ice extent during the last 30 years. The loss of sea ice creates new areas where, in winter, the relatively warm ocean loses heat to the cold atmosphere. As warm air rises, the warming reduces the sea level air pressure, changing the atmospheric circulation to develop a local anticlockwise wind system centered over the northern Barents Sea. The associated eastward winds in the Barents Sea Opening and southeastward winds in Fram Strait affect how warm water from the North Atlantic moves toward the Arctic. There has been a long debate on whether this wind anomaly can increase the warm Atlantic Water transport into the Barents Sea and thus cause a positive feedback mechanism for further reducing the sea ice through melting. We find that the observed atmospheric circulation changes have no significant impact on the Barents Sea warm water inflow and thus reject the wind feedback as a strong player in contributing to Arctic Amplification. However, strong anomalous southeastward winds in Fram Strait and the northern Nordic Seas cause a southward shift of the warm Atlantic Water recirculation and reduce its flow toward the Arctic.
    Description: Key Points: A hypothesis that a wind feedback contributes to Arctic Amplification is rejected by performing dedicated wind perturbation simulations. Winter sea ice retreat in the northern Barents Sea causes anomalous cyclonic winds by locally enhancing ocean heat loss. Anomalous cyclonic winds result in less Atlantic Water transport through Fram Strait.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: North‐German Supercomputing Alliance
    Description: https://github.com/FESOM/fesom2
    Description: https://doi.org/10.7265/N5K072F8
    Description: https://doi.org/10.5065/D6HH6H41
    Description: https://doi.org/10.5065/D6WH2N0S
    Description: https://github.com/FESOM/pyfesom2
    Description: https://doi.org/10.5281/zenodo.7458143
    Keywords: ddc:551 ; Barents Sea ; Arctic Amplification ; feedback ; Atlantic water ; modeling ; Fram Strait
    Language: English
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  • 21
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    Experimental Evidence for Shear‐Induced Melting and Generation of Stishovite in Granite at Low (〈18 GPa) Shock Pressure (2023)
    Details
    Publication Date: 2023-12-04
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Knowledge of the shock behavior of planetary materials is essential to interpret shock metamorphism documented in rocks at hypervelocity impact structures on Earth, in meteorites, and in samples retrieved in space missions. Although our understanding of shock metamorphism has improved considerably within the last decades, the effects of friction and plastic deformation on shock metamorphism of complex, polycrystalline, non‐porous rocks are poorly constrained. Here, we report on shock‐recovery experiments in which natural granite was dynamically compressed to 0.5–18 GPa by singular, hemispherically decaying shock fronts. We then combine petrographic observations of shocked samples that retained their pre‐impact stratigraphy with distributions of peak pressures, temperatures, and volumetric strain rates obtained from numerical modeling to systematically investigate progressive shock metamorphism of granite. We find that the progressive shock metamorphism of granite observed here is mainly consistent with current classification schemes. However, we also find that intense shear deformation during shock compression and release causes the formation of highly localized melt veins at peak pressures as low as 6 GPa, which is an order of magnitude lower than currently thought. We also find that melt veins formed in quartz grains compressed to >10–12 GPa contain the high‐pressure silica polymorph stishovite. Our results illustrate the significance of shear and plastic deformation during hypervelocity impact and bear on our understanding of how melt veins containing high‐pressure polymorphs form in moderately shocked terrestrial impactites or meteorites.〈/p〉
    Description: Plain Language Summary: When asteroids, comets, or smaller fragments thereof impact the solid surfaces of planets, moons, or other asteroids, the rocks they strike undergo sudden and irreversible changes while an impact crater forms. These material changes are called shock metamorphism and result from the extremely high pressures, temperatures, and deformation rates caused by the impact. However, the role of rapid shear deformation on impact heating and shock metamorphism is poorly understood. Using a novel experimental setup, we performed shock‐wave experiments with granite, a naturally occurring rock, that allows us to study the role of extreme deformation rates during impact‐crater formation. Furthermore, our experimental setup allows us to avoid several pitfalls such as excavation and ejection of shocked material from a growing impact crater or multiple reflections of shock waves at sample containers that typically plagued previous experiments. We find that intense shear deformation during crater formation results in significant but highly localized heating. This additional heating causes melting of granite at shock pressures as low as 6 GPa, which is about 10 times less than currently thought. Our findings may explain how thin melt veins often observed in shock‐metamorphosed meteorites or rocks sampled from terrestrial impact craters have formed.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We performed shock recovery experiments with granite and spherically decaying compressive waves; numerical models constrain peak pressures〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Shocked granite samples are found to retain pre‐impact stratigraphy and to document shock‐stage transitions between 〈0.5 and ∼18 GPa〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Shear‐induced melting of granite at bulk peak pressures as low as 6 GPa; stishovite nucleated as a liquidus phase in melt veins at >10 GPa〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Japan Society for the Promotion of Science
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:https://isale-code.github.io/terms-of-use.html ; ddc:https://doi.org/10.5281/zenodo.7881492 ; ddc:552 ; shock metamorphism ; granite ; stishovite ; melt vein ; shock recovery ; numerical modeling
    Language: English
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  • 22
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    Anorthositic lunar regolith breccia Dhofar 1769—Clear indications for repeated mixing of impact melt lithologies (2023)
    Details
    Publication Date: 2023-12-04
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The lunar regolith breccia Dhofar 1769, which was found in 2012 as a single 125 g piece in the Zufar desert area of Oman, contains a relatively large, dark‐colored impact melt breccia embedded in a fine‐grained clastic matrix. The internal texture of the fragment indicates the repeated melt breccia formation on the lunar surface, their repeated brecciation, and mixing in second, third, and fourth generations of brecciated rock types. The chemical and mineralogical data reveal the incorporation of a feldspar‐rich subophitic crystalline melt within a feldspar‐rich microporphyritic crystalline melt breccia. This lithic paragenesis itself is embedded within a mafic, crystalline melt breccia. The entire breccia with the three different impact melts has been finally incorporated into the whole rock breccia. The three impact melts are mixtures of different source rocks and impact projectiles, based on the obtained minor and trace element compositions (in particular of Ni and the rare earth elements [REE]) of the impact melt lithologies. For all processes of impact melt formation, additional steps of their brecciation and re‐lithification require a minimum number of seven impact processes.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:552 ; Dhofar 1769 ; lunar regolith breccia ; impact melt formation ; brecciation ; re-lithification ; impact processes
    Language: English
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  • 23
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    Observations of Gravity Wave Refraction and Its Causes and Consequences (2023)
    Details
    Publication Date: 2023-11-28
    Description: Horizontal gravity wave (GW) refraction was observed around the Andes and Drake Passage during the SouthTRAC campaign. GWs interact with the background wind through refraction and dissipation. This interaction helps to drive midatmospheric circulations and slows down the polar vortex by taking GW momentum flux (GWMF) from one location to another. The SouthTRAC campaign was composed to gain improved understanding of the propagation and dissipation of GWs. This study uses observational data from this campaign collected by the German High Altitude Long Range research aircraft on 12 September 2019. During the campaign a minor sudden stratospheric warming in the southern hemisphere occurred, which heavily influenced GW propagation and refraction and thus also the location and amount of GWMF deposition. Observations include measurements from below the aircraft by Gimballed Limb Observer for Radiance Imaging of the Atmosphere and above the aircraft by Airborne Lidar for the Middle Atmosphere. Refraction is identified in two different GW packets as low as ≈4 km and as high as 58 km. One GW packet of orographic origin and one of nonorographic origin is used to investigate refraction. Observations are supplemented by the Gravity‐wave Regional Or Global Ray Tracer, a simplified mountain wave model, ERA5 data and high‐resolution (3 km) WRF data. Contrary to some previous studies we find that refraction makes a noteworthy contribution in the amount and the location of GWMF deposition. This case study highlights the importance of refraction and provides compelling arguments that models should account for this.
    Description: Plain Language Summary: Gravity waves (GWs) are very important for models to reproduce a midatmospheric circulations. But the fact is that models oversimplify the GW physics which results in GWs being underrepresented in models. GW refraction is one of the processes not captured by the physics in model parameterization schemes. This article uses high‐resolution observations from the SouthTRAC campaign to show how GWs refract and highlight the importance there‐of. This case study shows a 25% increase in the GWMF during propagation. The increase in momentum flux is linked to refraction which results in a shortening in the GW horizontal wavelength. This article shows that refraction is important for the amount as well as the location of GWMF deposition. This case study highlights the importance of refraction and provides compelling arguments that models should account for this.
    Description: Key Points: A case study reveals that refraction results in a 25% increase in gravity wave momentum flux (GWMF). Including refraction dynamics affects the location of GWMF deposition. Refraction is prominent in strong wind gradients (i.e., displaced vortex conditions).
    Description: ANPCYT PICT
    Description: DFG
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Instituto de Física de Buenos Aires
    Description: SNCAD MinCyT initiative
    Description: HALO‐SPP
    Description: ROMIC WASCLIM
    Description: https://doi.org/10.5281/zenodo.6997443
    Description: https://cds.climate.copernicus.eu/cdsapp%23%21/home
    Keywords: ddc:551.5 ; gravity wave ; mountain wave ; refraction ; Andes ; Drake Passage ; gravity wave momentum flux
    Language: English
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  • 24
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    The Impact of Different Atmospheric CO2 Concentrations on Large Scale Miocene Temperature Signatures (2023)
    Hossain, Akil ; Knorr, Gregor ; Jokat, Wilfried ; [et al.]
    Details
    Publication Date: 2023-11-23
    Description: Based on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO〈sub〉2〈/sub〉 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO〈sub〉2〈/sub〉 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO〈sub〉2〈/sub〉 level of 450 ppm. An increase of atmospheric CO〈sub〉2〈/sub〉 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO〈sub〉2〈/sub〉 concentrations. At such CO〈sub〉2〈/sub〉 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO〈sub〉2〈/sub〉 increase from 280 to 450 ppm, in comparison to weaker warming for CO〈sub〉2〈/sub〉 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO〈sub〉2〈/sub〉 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO〈sub〉2〈/sub〉 forcing at a warmer Miocene background climate.
    Description: Key Points: At a CO〈sub〉2〈/sub〉 level of 450 ppm, a Miocene simulation shows a global mean surface warming of +3.1°C relative to the preindustrial state. Atmospheric CO〈sub〉2〈/sub〉 increase from 280 to 450 ppm causes a warming of ∼1.4°C, which is as strong as all other forcing factors combined. At higher atmospheric CO〈sub〉2〈/sub〉 levels, the Miocene climate shows a reduced polar amplification linked to a breakdown of seasonality in the Arctic.
    Description: Alfred Wegener Institute
    Description: Helmholtz Centre for Polar and Marine Research
    Description: https://doi.org/10.1594/PANGAEA.943430
    Description: https://github.com/FESOM/fesom2/
    Description: https://mpimet.mpg.de/en/science/modeling-with-icon/code-avilability
    Keywords: atmospheric CO2 ; Miocene ; Miocene temperature change ; polar amplification ; climate modeling ; Miocene bathymetry
    Language: English
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  • 25
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    The Climatology of Elevated Stratopause Events in the UA‐ICON Model and the Contribution of Gravity Waves (2023)
    Details
    Publication Date: 2023-11-23
    Description: The climatologies of the stratopause height and temperature in the UA‐ICON model are examined by comparing them to 17‐years (2005–2021) of Microwave Limb Sounder (MLS) observations. In addition, the elevated stratopause (ES) event occurrence, their main characteristics, and driving mechanisms in the UA‐ICON model are examined using three 30‐year time‐slice experiments. While UA‐ICON reasonably simulates the large‐scale stratopause properties similar to MLS observations, at polar latitudes in the Southern Hemisphere the stratopause is ∼8 K warmer and ∼3 km higher than observed. A time lag of about two months also exists in the occurrence of the tropical semiannual oscillation of the stratopause compared to the observations. ES events occur in ∼20% of the boreal winters, after major sudden stratospheric warmings (SSWs). Compared to the SSWs not followed by ES events (SSW‐only), the ES events are associated with the persistent tropospheric forcing and prolonged anomalies of the stratospheric jet. Our modeling results suggest that the contributions of both gravity waves (GW)s and resolved waves are important in explaining the enhanced residual circulation following ES events compared to the SSW‐only events but their contributions vary through the lifetime of ES events. We emphasize the role of the resolved wave drag in the ES formation as in the sensitivity test when the non‐orographic GW drag is absent, the anomalously enhanced resolved wave forcing in the mesosphere gives rise to the formation of the elevated stratopause at about 85 km.
    Description: Plain Language Summary: Using 17 years (2005–2021) of Microwave Limb Sounder (MLS) observations, we show negative (cooling stratopause temperatures and decreasing stratopause heights) trends in most regions and seasons. The largest negative trend in the stratopause temperature (by considering all regions and all seasons) is found in the Southern Hemisphere (SH)'s polar region during austral spring. The seasonal average of cooling rates is comparable in the mid‐latitudes of Northern Hemisphere and SH. In the UA‐ICON simulations, the elevated stratopause events (ESEs) occur after major sudden stratospheric warmings (SSWs). ESEs frequency is 2 events per decade in UA‐ICON simulations. Our results show that the wind reversal is stronger and long‐lasting in the ESEs compared to SSW‐only events. In addition, the easterlies extend to the mesosphere in the composites of ESEs, but the reversed winds are limited to below 60 km in the case of SSW‐only events. We show that the non‐orographic gravity wave drag induces anomalous residual circulation after SSW that causes the ESEs. We also show that the ESEs form even in the absence of non‐orographic gravity wave drag. In this case, the anomalous residual circulation is due to the anomalously enhanced resolved wave forcing in the mesosphere that gives rise to the formation of the ESEs at about 85 km.
    Description: Key Points: The largest stratopause trend is found in the Southern Hemisphere polar region during austral springbased on Microwave Limb Sounder observations. The suppression of gravity waves in UA‐ICON reveals the importance of resolvedwaves and their ability to compensate missing drag. In the polar regions, the simulated stratopause is too warm and the tropical semi‐annual oscillation is about two months out of phase.
    Description: Deutsche Forschungsgemeinschaft
    Description: Transregional Collaborative Research Centre
    Description: GACR
    Description: MS‐GWaves
    Description: https://code.mpimet.mpg.de/projects/iconpublic
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_ctrl
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_nonon
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_nosso
    Keywords: ddc:551.5 ; gravity waves ; elevated stratopause ; middle atmosphere
    Language: English
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    Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins? (2023)
    Details
    Publication Date: 2023-11-23
    Description: Offshore meteoric groundwater (OMG) has long been hypothesized to be a driver of seafloor geomorphic processes in continental margins worldwide. Testing this hypothesis has been challenging because of our limited understanding of the distribution and rate of OMG flow and seepage, and their efficacy as erosive/destabilizing agents. Here we carry out numerical simulations of groundwater flow and slope stability using conceptual models and evolving stratigraphy—for passive siliciclastic and carbonate margin cases—to assess whether OMG and its evolution during a late Quaternary glacial cycle can generate the pore pressures required to trigger mechanical instabilities on the seafloor. Conceptual model results show that mechanical instabilities using OMG flow are most likely to occur in the outer shelf to upper slope, at or shortly before the Last Glacial Maximum sea‐level lowstand. Models with evolving stratigraphy show that OMG flow is a key driver of pore pressure development and instability in the carbonate margin case. In the siliciclastic margin case, OMG flow plays a secondary role in preconditioning the slope to failure. The higher degree of spatial/stratigraphic heterogeneity of carbonate margins, lower shear strengths of their sediments, and limited generation of overpressures by sediment loading may explain the higher susceptibility of carbonate margins, in comparison to siliciclastic margins, to mechanical instability by OMG flow. OMG likely played a more significant role in carbonate margin geomorphology (e.g., Bahamas, Maldives) than currently thought.
    Description: Plain Language Summary: The flow of fresh to brackish groundwater has been proposed as an important process shaping the seafloor. However, we still have a poor understanding of how groundwater behaves in the sub‐seafloor and whether it can erode seafloor sediments. In this study, we test this hypothesis by using conceptual and realistic numerical models of two common types of seafloor margins—siliciclastic and carbonate—to assess the role of groundwater in making the seafloor susceptible to erosion. We show that the flow of groundwater offshore could have driven seafloor erosion close to the shelf break during the Last Ice Age, when sea level was lower than at present. Carbonate margins are more susceptible to this type of failure than siliciclastic margins. This may be explained by the higher variability in sediment properties across carbonate margins as well as the lower strength of their sediments. Groundwater has likely played an important role in shaping the seafloor in carbonate margins, and it may be responsible for landforms such as canyons, scars, and depressions in the Bahamas and the Maldives.
    Description: Key Points: Offshore meteoric groundwater (OMG) flow can drive mechanical instabilities in the outer shelf to upper slope. Such instabilities occur at, or shortly after, the Last Glacial Maximum sea‐level lowstand. Carbonate margins are more susceptible to mechanical instability by OMG than siliciclastic margins.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.5281/zenodo.7094202
    Description: https://www.rocscience.com/software/slide2
    Description: https://figshare.com/s/5336d42d19ef771d4ad8
    Description: https://figshare.com/s/5027cd5ca22a7e96b3d1
    Keywords: ddc:551.3 ; offshore groundwater ; mechanical instability ; continental margins ; seafloor geomorphology ; siliciclastic ; carbonate
    Language: English
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  • 27
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    Toward Better Constrained Scattering Models for Natural Ice Crystals in the Visible Region (2023)
    Details
    Publication Date: 2023-11-23
    Description: In this work, we introduce a method for constraining the optical scattering models of natural ice crystals based on in‐situ measurements. Specifically the measured angular scattering functions for ice crystals can be used to compute a set of the asymmetry parameter (g) and the corresponding complexity parameter (C〈sub〉p〈/sub〉). It is demonstrated that the g‐C〈sub〉p〈/sub〉 relation can give valuable information on the morphology of ice crystal. The validity of the methods is shown from theoretical perspectives and the geometric‐optics ray‐tracing simulations. As an application, we investigate rimed ice crystals from in‐situ measurements and found that (a) the C〈sub〉p〈/sub〉 parameter is very well correlated with the surface riming degree and (b) only those models with both roughness and internal scattering can explain the observed g‐C〈sub〉p〈/sub〉 relation for rimed particles.
    Description: Plain Language Summary: Light scattering models of ice crystals are important for remote sensing and climate studies. Yet, many physical parameters, such as shape, aspect ratio, and inhomogeneity of the ice crystal can impose significant uncertainty in the single‐scattering properties predicted by light scattering models. To reduce such uncertainty and constrain the physical parameters in modeling, we introduce a novel method by analyzing the in‐situ measurement of the phase functions of ice crystals. We demonstrate the validity and usefulness of the method using both geometric ray‐tracing simulations and a case study on rimed crystals from two campaigns.
    Description: Key Points: A method is developed for analyzing in‐situ polar nephelometer measurements, aiming for constraining the light scattering models for natural ice crystal. Validity of the method is demonstrated by geometric‐optics ray‐tracing simulations and in‐situ measurements. A case study of rimed crystals measured in‐situ during two aircraft field campaigns using the Particle Habit Imaging and Polar Scattering probe is presented.
    Description: Helmholtz Association's Initiative and Networking Fund
    Description: https://doi.org/10.1594/PANGAEA.902611
    Description: https://doi.org/10.5065/D6639NKQ
    Description: https://zenodo.org/badge/latestdoi/440147565
    Keywords: ddc:551.5 ; light scattering ; ice crystals
    Language: English
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    Pre‐Eruptive Outgassing and Pressurization, and Post‐Fragmentation Bubble Nucleation, Recorded by Vesicles in Breadcrust Bombs From Vulcanian Activity at Guagua Pichincha Volcano, Ecuador (2023)
    Details
    Publication Date: 2023-11-23
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Breadcrust bombs formed during Vulcanian eruptions are assumed to originate from the shallow plug or dome. Their rim to core texture reflects the competition between cooling and degassing timescales, which results in a dense crust with isolated vesicles contrasting with a highly vesicular vesicle network in the interior. Due to relatively fast quenching, the crust can shed light on pre‐ and syn‐eruptive conditions prior to or during fragmentation, whereas the interior allows us to explore post‐fragmentation vesiculation. Investigation of pre‐ to post‐fragmentation processes in breadcrust bombs from the 1999 Vulcanian activity at Guagua Pichincha, Ecuador, via 2D and 3D textural analysis reveals a complex vesiculation history, with multiple, spatially localized nucleation and growth events. Large vesicles (Type 1), present in low number density in the crust, are interpreted as pre‐eruptive bubbles formed by outgassing and collapse of a permeable bubble network during ascent or stalling in the plug. Haloes of small, syn‐fragmentation vesicles (Type 2), distributed about large vesicles, are formed by pressurization and enrichment of volatiles in these haloes. The nature of the pressurization process in the plug is discussed in light of seismicity and ground deformation signals, and previous textural and chemical studies. A third population (Type 3) of post‐fragmentation small vesicles appears in the interior of the bomb, and growth and coalescence of Type 2 and 3 vesicles causes the transition from isolated to interconnected bubble network in the interior. We model the evolution of viscosity, bubble growth rate, diffusion timescales, bubble radius and porosity during fragmentation and cooling. These models reveal that thermal quenching dominates in the crust whereas the interior undergoes a viscosity quench caused by degassing, and that the transition from crust to interior corresponds to the onset of percolation and development of permeability in the bubble network.〈/p〉
    Description: Plain Language Summary: Breadcrust bombs are volcanic ejecta formed during explosive volcanic eruptions by rapid cooling of the exterior (the crust) and slow cooling of the interior that causes gas loss, bubble growth and cracking of the exterior. The rapidly cooled crust preserves characteristics of the magma prior to explosion. We study here the variations in porosity and vesicle properties from crust to interior in breadcrust bombs from the Guagua Pichincha volcano in Ecuador. Our results shed light on the pre‐eruptive conditions in the magma prior to explosive activity, and on the post‐fragmentation evolution of the bomb interior by bubble formation.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Vesicle textures in breadcrust bombs correlate with pre‐ to post‐fragmentation degassing processes during Vulcanian eruptions〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Large isolated vesicles preserved in the crust record a pre‐eruptive episode of outgassing and pressurization prior to fragmentation〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Small vesicles provide insights into post‐fragmentation onset of permeability from the crust to the interior〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: ERC
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: National Science Foundation
    Description: German Research Foundation
    Description: https://doi.org/10.26022/IEDA/112846
    Keywords: ddc:552 ; breadcrust bombs ; Vulcanian eruptions ; vesicle number density ; vesiculation ; bubble nucleation ; fragmentation
    Language: English
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  • 29
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    Influence of Inner Surface Roughness on the Spectral Induced Polarization Response—A Numerical Study (2023)
    Details
    Publication Date: 2023-11-23
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Spectral induced polarization (SIP) laboratory measurements on water‐saturated rocks show a strong correlation between the electrical polarization strength and the inner surface area of rocks. We investigate the influence of inner surface roughness on the SIP response by simulating the frequency‐dependent complex conductivity of micro‐scale rock models. Starting with smooth grain models, we introduce surface roughness using two different approaches: increasing the surface roughness in a fractal‐like manner, and creating random surface structures, resulting in more natural‐looking surfaces. We find that surface roughness has two distinct effects on the SIP response: (a) a shift in the position and magnitude of the primary relaxation frequency to lower frequencies and lower magnitudes, respectively, and (b) the formation of secondary polarizations above the polarization frequency of the primary polarization. We also compare the relaxation time and normalized chargeability obtained by Debye decomposition and the imaginary conductivity at 1 Hz of our models with mechanistic models and empirical relations. We point out the congruences and offer explanations for the discrepancies between our models and the empirical observations. We conclude that the results of our study are applicable to real rocks and that the SIP method has the potential to detect inner surface roughness. However, the SIP method it not able to discriminate between signals from rough particles and a distribution of smooth particles.〈/p〉
    Description: Plain Language Summary: The spectral induced polarization method measures the electrical conductivity of the subsurface at depths of investigation ranging from a few dm to several 100 m. The potential of the method to detect mineral resources, contamination, microbial activity, etc. makes it a promising tool for today's environmental challenges. However, due to the complexity of the underlying physical and chemical processes the interpretation of SIP measurements often remains qualitative. Mathematical and mechanistic models used to describe the processes are usually simplified with respect to geometry, chemistry, and physical properties. In this study, we use computer simulations to investigate the surfaces of spherical particles (grains). After simulating the SIP response of models with smooth and rough surfaces, we analyze the influence of surface roughness on the SIP response. We find that surface roughness causes distinct changes in the SIP response compared to the smooth grain. However, we also find that this introduces an ambiguity in the interpretation of SIP data.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Inner surface roughness of rocks has substantial impact on spectral induced polarization response〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Surface roughness shifts the primary polarization peak to lower frequencies〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Surface roughness causes additional polarizations above the primary peak frequency〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: https://doi.org/10.5281/ZENODO.7049722
    Keywords: ddc:550 ; SIP ; surface ; roughness
    Language: English
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  • 30
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    Wind Power Input to Ocean Near‐Inertial Waves Diagnosed From a 5‐km Global Coupled Atmosphere‐Ocean General Circulation Model (2023)
    Details
    Publication Date: 2023-11-27
    Description: Using the 5 km coupled general circulation model ICON, the surface internal wave energy source, crucial for the oceanic circulation, is quantified as the wind‐induced wave energy flux that radiates from the mixed layer bottom (MLB) into the ocean interior. Our result lowers the previous estimates of the wind power input to surface near‐inertial motions from up to more than 1 TW down to about 0.23–0.27 TW, depending on season. We point out that the estimate of the wind input to ocean depends not only on the wind stress used—as suggested by previous studies—but also on the ocean model used. While the surface currents in a slab ocean model or a non‐eddying ocean circulation model are strongly determined by the wind forcing, the surface currents in the 5 km ICON model can be more strongly determined by internal instability process (eddy) than by wind stress forcing from less‐extreme weather disturbances. The resulting more or less random alignment of surface current and wind stress can presumably lead to a lower wind input to surface near‐inertial motions. Of the surface wave energy source, about 30% is fluxed down into the interior ocean. This percentage roughly doubles those from previous studies, due to the stronger wave energy flux related to stronger inertial waves generated by the tropical cyclones simulated by the 5 km ICON model. Overall, the low wind input at near‐inertial frequencies produces a wind‐induced wave energy source at the MLB that is well below 0.1 TW.
    Description: Plain Language Summary: For maintaining the oceanic overturning circulation, energy is needed to mix the dense water up and light water down. The main energy source for mixing arises from breaking of internal waves. A considerable portion of this source comes from waves excited by winds at the sea surface. This paper quantifies this wave energy source based on a frontier simulation of a coupled atmosphere‐ocean general circulation model at a horizontal resolution of 5 km. This model is capable to simulate tropical cyclones (hurricanes and typhoons) and less‐extreme small‐scale and short‐living weather disturbances and oceanic mesoscale eddies, which were not represented by the models used in most of the previous studies. Taking these new features into account, we find that the wind‐induced wave energy source is less than 0.1 TW.
    Description: Key Points: Relatively low wind power input to near‐inertial motions in a 5 km global coupled simulation. Energy flux radiating from the mixed layer bottom as interior wave energy source. Strong internal waves excited by tropical cyclones simulated by a 5 km global coupled general circulation model.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: http://hdl.handle.net/21.11116/0000-000A-C1FA-2
    Keywords: ddc:551.5 ; wind‐induced wave energy source ; km‐scale coupled GCM ; internal waves generated by tropical cyclones
    Language: English
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  • 31
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    On the Dynamical Importance of Gravity Wave Sources Distributed Over Different Heights in the Atmosphere (2023)
    Details
    Publication Date: 2023-11-27
    Description: Gravity waves (GWs) are generated at all altitudes in the atmosphere, but sources above the lower stratosphere are rarely considered by parameterizations employed in general circulation models. This study assesses the potential impact on the thermosphere produced by small‐scale waves originating at different heights. Within the proposed numerical framework, GW sources are represented by wave momentum forcing, whose values are expressed relative to the forcing required to obtain typical wave spectra around the tropopause. The relative importance of tropospheric and extra‐tropospheric sources and the response in the thermosphere are studied in a series of sensitivity experiments. They demonstrate that the accumulation of wave momentum steeply drops with height as a consequence of decreasing density, even when the forcing is maintained at a uniform level throughout the middle atmosphere. When a broad spectrum is forced at twice the tropospheric rate, the thermospheric drag is increased by only a factor of two, and that increase is produced by waves that were forced in the lower stratosphere. With increasing altitude, vertically localized sources contribute progressively less. For example, for GWs excited near the mesopause to produce an impact comparable with that due to waves propagating from below, the forcing must be orders of magnitude stronger than in the troposphere. The estimated forcing of the so‐called secondary harmonics by breaking primary waves is much weaker, such that the systematic dynamical effect of secondary waves in the thermosphere is negligible compared to that of the primary GWs generated in the troposphere.
    Description: Plain Language Summary: Multiple observations demonstrate that gravity waves (GWs) are generated at all atmospheric levels, however numerical general circulation models employing parameterizations that account for wave sources only in the troposphere are able to reproduce the state and dynamics of the middle and upper atmosphere reasonably well. Assessing the role of GWs generated above the troposphere is extremely challenging, because such waves are difficult to separate from those of tropospheric origin in observations. The mechanisms of wave generation in the middle atmosphere are very complex and not fully understood. We developed a numerical framework, in which the strength of the extra‐tropospheric sources is represented by multiples of those in the troposphere. In the series of sensitivity tests, we demonstrate that the contribution of sources to the total wave momentum drops with height following the density decrease, and that the tropospheric sources capture the major part of the total momentum and of the associated GW drag in the thermosphere. One of the conclusions of this study is that the impact in the thermosphere of secondary waves, which are believed to be excited near the mesopause, is negligible compared to that of primary waves propagating from the troposphere.
    Description: Key Points: A framework for assessing impacts of gravity waves generated by sources distributed over all heights in the middle atmosphere is developed. The thermospheric response to sources above the tropopause is primarily produced by waves generated in the lower. stratosphere Localized sources produce negligible thermospheric drag unless the forcing is orders of magnitude stronger than in the troposphere.
    Description: Earth Sciences Division http://dx.doi.org/10.13039/100014573
    Description: https://kauai.ccmc.gsfc.nasa.gov/instantrun/hwm
    Description: https://ccmc.gsfc.nasa.gov/modelweb/models/nrlmsise00.php
    Keywords: ddc:551.5 ; gravity waves ; wave sources ; thermosphere ; secondary waves ; middle atmosphere
    Language: English
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  • 32
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    Systematic Across‐Arc Variations of Molybdenum Isotopes in a Fluid‐Dominated Subduction Zone System (2023)
    Details
    Publication Date: 2023-11-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Mass‐dependent Mo isotope variations are a promising new tracer to study magmatic processes in different geological settings. We report the first Mo isotope data for the Kamchatka arc system in the Northwest Pacific, comprising basaltic lavas of a complete Southeast‐Northwest traverse from the volcanic arc front through to the back arc region. The majority of volcanic centers investigated directly override the Hawaii‐Emperor Seamount Chain, which is currently being subducted underneath the arc system. Our Mo isotope data show systematic trends with Ce/Pb, Ce/Mo, Nb/Zr, La/Sm, and 〈sup〉143〈/sup〉Nd/〈sup〉144〈/sup〉Nd ratios from the volcanic arc front to the back arc. Arc front lavas have higher δ〈sup〉98/95〈/sup〉Mo and lower Ce/Pb, Ce/Mo, Nb/Zr, La/Sm compared to back arc lavas. Because the involvement of subducted sediments can be excluded, we attribute the observed variations to a change in the mantle source composition from the arc front to the back arc regions. The isotopic and chemical budget of arc front lavas is dominated by a slab fluid component (high δ〈sup〉98/95〈/sup〉Mo, low Ce/Pb, Ce/Mo), whereas mantle‐like Ce/Pb, Ce/Mo, elevated Nb/Zr and La/Sm in the back arc samples suggest an enriched mantle source. Combined δ〈sup〉98/95〈/sup〉Mo, Nd, and Pb isotope data in back arc lavas are very similar to those observed for modern ocean island basalts from Hawaii. We thus explore the possibility that the back arc mantle was contaminated by a Hawaii‐type, enriched asthenospheric mantle component from the subducted Hawaii‐Emperor Seamount Chain.〈/p〉
    Description: Plain Language Summary: In subduction zones, tectonic plates—tens of kilometers thick and making up the outer shell of our planet—are on a collision course. Although the absolute convergence rates of these plates are minute (a few cm/year), the forces in this process are so large that one plate is pushed under the other, causing the lower plate to be recycled into the Earth's mantle over time scales of millions of years. The tangible consequences are high‐magnitude earthquakes and large‐volume volcanic eruptions along these convergent plate margins. It is thus important to better understand the geological processes that operate in subduction zones. Here, we have studied the chemical and isotopic composition of volcanic rocks from the Kamchatka subduction zone. Our results confirm that water, locked into the subducting plate while residing on the surface, is released into the hot, overlying mantle after subduction, causing the formation of large volumes of magma that eventually erupt in volcanoes on the Kamchatka Peninsula. Our data also indicate that the subducting plate, once pushed into the mantle, is being ripped apart, allowing buoyant mantle material from greater depth to rise and contribute to the large‐scale volcanism observed along this convergent plate margin.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Molybdenum isotope systematics in arc basalts from Kamchatka are consistent with presence of a slab‐derived fluid in their mantle source〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Back arc basalts also show contribution from a geochemically enriched source〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Combined Mo, Nd, and Pb isotope and trace element data for back arc basalts suggest involvement of Hawaii‐type asthenospheric mantle〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.25625/P5BBFL
    Keywords: ddc:551.9 ; molybdenum isotopes ; slab fluid ; enriched mantle ; subduction ; Kamchatka ; Hawaii
    Language: English
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  • 33
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    Constraints for the Martian Crustal Structure From Rayleigh Waves Ellipticity of Large Seismic Events (2023)
    Details
    Publication Date: 2023-11-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉For the first time, we measured the ellipticity of direct Rayleigh waves at intermediate periods (15–35 s) on Mars using the recordings of three large seismic Martian events, including S1222a, the largest event recorded by the InSight mission. These measurements, together with P‐to‐s receiver functions and P‐wave reflection times, were utilized for performing a joint inversion of the local crustal structure at the InSight landing site. Our inversion results are compatible with previously reported intra‐crustal discontinuities around 10 and 20 km depths, whereas the preferred models show a strong discontinuity at ∼37 km, which is interpreted as the crust‐mantle interface. Additionally, we support the presence of a shallow low‐velocity layer of 2–3 km thickness. Compared to nearby regions, lower seismic wave velocities are derived for the crust, suggesting a higher porosity or alteration of the whole local crust.〈/p〉
    Description: Plain Language Summary:: As never before on Mars, we measured the characteristics of seismic waves traveling along the Martian surface that carry information about the crustal structure at the InSight site. We combined these measurements with two other local‐scale independent observations to derive a consolidated model for the crust underneath the InSight lander. Our results suggest a Martian crust with 4 layers and, particularly, one thin layer of about 2 km thickness close to the surface. The crust‐mantle discontinuity was found at ∼37 km depth, where the sharpest change in seismic wave velocity is observed. Overall, the seismic wave velocities of the local Martian crust at the InSight site are lower than those derived in other regions on Mars, which suggests a higher porosity or local alteration.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Rayleigh waves ellipticity was measured between periods 15–35 s at the InSight landing site using large seismic events, including S1222a〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉A 4‐layer crust, including a shallow low‐velocity layer, is required to explain the ellipticity, receiver functions and P‐wave lag times〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Low crustal velocities are derived for the InSight site, which may be due to high porosity or heavy alteration at local scale〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: National Aeronautics and Space Administration
    Description: Agence Nationale de la Recherche http://dx.doi.org/10.13039/501100001665
    Description: https://doi.org/10.12686/a19
    Description: https://doi.org/10.18715/SEIS.INSIGHT.XB_2016
    Description: https://doi.org/10.7914/SN/BQ
    Description: https://www.globalcmt.org/CMTsearch.html
    Description: https://github.com/scarrascom/Rellipy
    Description: https://doi.org/10.5281/zenodo.8051337
    Description: http://www.geopsy.org/
    Keywords: ddc:523 ; martian crust ; marsquakes ; Rayleigh waves ellipticity ; receiver functions
    Language: English
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  • 34
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    Microphysical Pathways Active Within Thunderstorms and Their Sensitivity to CCN Concentration and Wind Shear (2023)
    Details
    Publication Date: 2023-11-02
    Description: The impact of cloud condensation nuclei (CCN) concentration on microphysical processes within thunderstorms and the resulting surface precipitation is not fully understood yet. In this work, an analysis of the microphysical pathways occurring in these clouds is proposed to systematically investigate and understand these sensitivities. Thunderstorms were simulated using convection‐permitting (1 km horizontal grid spacing) idealized simulations with the ICON model, which included a 2‐moment microphysics parameterization. Cloud condensation nuclei concentrations were increased from 100 to 3,200 CCN/cm3, in five different wind shear environments ranging from 18 to 50 m/s. Large and systematic decreases of surface precipitation (up to 35%) and hail (up to 90%) were found as CCN was increased. Wind shear changes the details, but not the sign, of the sensitivity to CCN. The microphysical process rates were tracked throughout each simulation, closing the mass budget for each hydrometeor class, and collected together into “microphysical pathways,” which quantify the different growth processes leading to surface precipitation. Almost all surface precipitation occurred through the mixed‐phase pathway, where graupel and hail grow by riming and later melt as they fall to the surface. The mixed‐phase pathway is sensitive to CCN concentration changes as a result of changes to the riming rate, which were systematically evaluated. Supercooled water content was almost insensitive to increasing CCN concentration, but decreased cloud drop size led to a large reduction in the riming efficiency (from 0.79 to 0.24) between supercooled cloud drops and graupel or hail, resulting in less surface precipitation.
    Description: Plain Language Summary: The amount of rain and hail from thunderstorms can be influenced by the amount of pollution in the form of aerosol particles, which determine how many cloud droplets form and how large they are. Unfortunately, different numerical models give different answers on whether rain and hail increase or decrease if pollution increases. In this article, we present a new analysis method helping to identify the small‐scale processes which are responsible for the increase or decrease in a specific numerical scheme. We apply it to simulations of thunderstorms and show that the decrease of rain and hail in the numerical model used here is mostly linked to the riming process. Riming is the collision of cloud droplets and frozen particles at temperatures below 0°C, such that the liquid water freezes to the surface of the ice particles and makes them bigger. Less riming occurs when pollution increases, because cloud droplets are smaller. This process is very important because nearly all rain reaching the surface consists of melted ice particles.
    Description: Key Points: Microphysical pathways are constructed by tracking microphysical processes rates and closing the hydrometeor mass budget. More cloud condensation nuclei lead to less surface precipitation and hail, due to smaller cloud drop sizes and reduced riming collection efficiency. Simulations with constant riming collection efficiency reveal two different hail formation pathways.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: HORIZON EUROPE European Research Council http://dx.doi.org/10.13039/100019180
    Description: https://doi.org/10.5445/IR/1000156063
    Keywords: ddc:551.5 ; convective clouds ; hail ; riming ; precipitation ; CCN ; convection‐permitting simulation
    Language: English
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  • 35
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    Aluminum Components in Bridgmanite Coexisting With Corundum and the CF‐Phase With Temperature (2023)
    Details
    Publication Date: 2023-11-02
    Description: Abstract Phase relations in the MgSiO〈sub〉3〈/sub〉–MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 system are investigated at 27 GPa and 2000–2600 K using a multi‐anvil apparatus. The AlAlO〈sub〉3〈/sub〉 content in the bridgmanite increases from 8.6 to 20.0 mol% with increasing temperature from 2000 to 2600 K, while the MgAlO〈sub〉2.5〈/sub〉 content remains nearly constant, that is, 3–4 mol% at these temperatures. Therefore, the presence of an additional Al‐bearing phase suppresses the oxygen vacancy substitution for Al〈sup〉3+〈/sup〉 in bridgmanite. Conversely, significant amounts of the Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 component can be dissolved into the calcium‐ferrite type MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉–Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 phase (CF‐phase), implying that the CF‐phase likely contains some amount of vacancies. Therefore, the CF‐phase could also be a candidate mineral for transporting volatiles into the lower mantle. Our results, combined with previous studies on Al‐bearing bridgmanite, indicate that, once the Al per formula unit exceeds 0.12 in bridgmanite, the MgAlO〈sub〉2.5〈/sub〉 content remains nearly constant and the AlAlO〈sub〉3〈/sub〉 component becomes dominant.
    Description: Plain Language Summary: Bridgmanite, the most abundant mineral in the Earth's mantle, can contain Al〈sup〉3+〈/sup〉 in the forms of MgAlO〈sub〉2.5〈/sub〉 and AlAlO〈sub〉3〈/sub〉. To constrain the substitution mechanism of Al〈sup〉3+〈/sup〉 in bridgmanite, we investigate the MgAlO〈sub〉2.5〈/sub〉 and AlAlO〈sub〉3〈/sub〉 contents in bridgmanite coexisting with a calcium‐ferrite type phase and corundum at different temperatures. Our results demonstrate that the MgAlO〈sub〉2.5〈/sub〉 content reaches saturation (3–4 mol%) when an additional Al‐bearing phase exists in the system.
    Description: Key Points: The MgAlO〈sub〉2.5〈/sub〉 content in bridgmanite remains constant with temperature when bridgmanite coexists with corundum and the CF‐phase. The MgAlO〈sub〉2.5〈/sub〉 content in bridgmanite reaches a solubility of 3–4 mol% when bridgmanite coexists with an additional Al‐bearing phase. A significant amount of the Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 component can be dissolved into the CF‐phase.
    Description: HORIZON EUROPE European Research Council http://dx.doi.org/10.13039/100019180
    Description: Japan Society for the Promotion of Science London http://dx.doi.org/10.13039/501100000646
    Description: cooperative research program of the Earthquake Research Institute
    Description: https://doi.org/10.5281/zenodo.7512647
    Keywords: ddc:549 ; Al‐bearing bridgmanite ; Al substitute mechanism ; phase relation ; volatile
    Language: English
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    The Linkage of Serial Cyclone Clustering in Western Europe and Weather Regimes in the North Atlantic‐European Region in Boreal Winter (2023)
    Hauser, Seraphine ; Mueller, Sebastian ; Chen, Xiaoyang ; [et al.]
    Details
    Publication Date: 2023-11-02
    Description: Extra‐tropical cyclones are an important source of weather variability in the mid‐latitudes. Multiple occurrences in a short period of time at a particular location are denominated serial cyclone clustering (SCC), and potentially lead to large societal impacts. We investigate the relationship between SCC affecting Western Europe and large‐scale weather regimes (WRs) in the North Atlantic‐European region in boreal winter. We find that SCC in low latitudes (45°N) is predominantly associated with the anticyclonic Greenland Blocking WR. In contrast, SCC in mid and high latitudes (55°N, 65°N) is mostly linked to different cyclonic WRs. Thereby, SCC occurs typically within a well‐established WR that builds up prior to SCC and decays after SCC. Thus, SCC events are closely associated with recurrent, quasi‐stationary and persistent large‐scale flow patterns (WRs). This mutual relationship reveals the potential of WRs in forecasting storm series and associated impacts on sub‐seasonal to seasonal time scales.
    Description: Plain Language Summary: Serial cyclone clustering describes the occurrence of multiple extra‐tropical cyclones within a certain time frame and a spatially restricted region. Since extra‐tropical cyclones can be associated with strong winds and heavy precipitation, multiple occurrences can lead to large cumulative impacts in the affected areas. We analyze the relationship between serial cyclone clustering (SCC) in Western Europe and so‐called weather regimes (WRs) in the North Atlantic‐European region in boreal winter. These regimes describe slow evolving and enduring large‐scale atmospheric circulation patterns. Relationships with certain regime types are identified but depend on the latitude at which the clustered frequency of extra‐tropical cyclones is found. When SCC occurs in low latitudes (45°N), it mostly appears coincident with anticyclonic large‐scale flow patterns. In contrast, SCC in mid and high latitudes (55°N, 65°N) often occurs simultaneously with different cyclonic regimes. We find that periods of SCC occur typically within WR life cycles pointing to the fact that both, the WRs and SCC periods, are interlinked. This relationship may facilitate forecasting storm series and associated impacts on time scales beyond 2 weeks.
    Description: Key Points: A close relationship is found between serial cyclone clustering (SCC) at 5°W and weather regimes (WRs) in the North Atlantic‐European region. SCC in mid and high latitudes (55°N, 65°N) is mainly associated with cyclonic and in low latitudes (45°N) with anticyclonic WR life cycles. Regardless of the selected latitude, SCC occurs mostly during an active regime life cycle and is manifested in a well‐established WR.
    Description: German Research Foundation
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: BMBF ClimXtreme
    Description: https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era-interim
    Keywords: ddc:551.5 ; serial cyclone clustering ; weather regimes ; atmospheric dynamics ; sub‐seasonal prediction
    Language: English
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    Soil resistivity measurements to evaluate subsoil salinity in rice production systems in the Vietnam Mekong Delta (2023)
    Details
    Publication Date: 2023-11-02
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Rice is a staple crop in the Vietnam Mekong Delta (VMD) in which more than half of Vietnam's rice is produced. However, rice production in the VMD is threatened by increasing saltwater intrusion due to land subsidence and climate change induced sea level rise. Saltwater intrusion into lowland areas through the canal system or capillary rise of saline water from near surface saline water tables may result in salt accumulation in the topsoil. Therefore, it is important to disentangle the two effects and their relative importance to implement appropriate strategies for water and salinity management for adapting rice production systems of the VMD to climate change. Here, we report on the possibility of using geoelectrical methods to evaluate the potential threat of subsoil salinity to rice production. To evaluate the level of subsoil salinity, we measured soil electrical resistivity using an ARES II to a depth of 40 m in a case study comprising five locations in the VMD. Electrical resistivity measurements were calibrated to soil types, which were identified through evaluating 1 m core sections obtained by drilling down to 40 m depth. The relationship between drilling data and soil resistivity was determined by applying clustering and principal component analysis. Resistivity values smaller than 3 Ω m were clearly identified as indicative for a saline water table. The results show a direct link between the depth of the saline water table and the proximity to the sea, but not to the rice production system (single, double, or triple cropping). This study proved for the first time the applicability of the electrical resistivity tomography method for identifying groundwater tables and evaluating subsoil salinity on an agricultural field scale in the VMD.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Federal Ministry of Education and Research (BMBF, Germany)
    Keywords: ddc:631.4 ; conductivity ; electrical resistivity tomography ; groundwater ; site effect
    Language: English
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  • 38
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    Twinned calcite as an indicator of high differential stresses and low shock pressure conditions during impact cratering (2023)
    Details
    Publication Date: 2023-11-02
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Shock‐related calcite twins are characterized in calcite‐bearing metagranite cataclasites within crystalline megablocks of the Ries impact structure, Germany, as well as in cores from the FBN1973 research drilling. The calcite likely originates from pre‐impact veins within the Variscan metagranites and gneisses, while the cataclasis is due to the Miocene impact. Quartz in the metagranite components does not contain planar deformation features, indicating low shock pressures (〈7 GPa). Calcite, however, shows a high density (>1/μm) of twins with widths 〈100 nm. Different types of twins (〈italic toggle="no"〉e〈/italic〉‐, 〈italic toggle="no"〉f‐〈/italic〉, and 〈italic toggle="no"〉r〈/italic〉‐twins) crosscutting each other can occur in one grain. Interaction of 〈italic toggle="no"〉r〈/italic〉‐ and 〈italic toggle="no"〉f〈/italic〉‐twins results in 〈italic toggle="no"〉a〈/italic〉‐type domains characterized by a misorientation relative to the host with a misorientation angle of 35°–40° and a misorientation axis parallel to an 〈italic toggle="no"〉a〈/italic〉‐axis. Such 〈italic toggle="no"〉a〈/italic〉‐type domains have not been recorded from deformed rocks in nature before. The high twin density and activation of different twin systems in one grain require high differential stresses (on the order of 1 GPa). Twinning of calcite at high differential stresses is consistent with deformation during impact cratering at relatively low shock pressure conditions. The twinned calcite microstructure can serve as a valuable low shock barometer.〈/p〉
    Description: Bavarian Natural History Collections
    Keywords: ddc:549 ; Ries impact structure ; twinned calcites ; cataclasis
    Language: English
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  • 39
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    Melting Alpine Water Towers Aggravate Downstream Low Flows: A Stress‐Test Storyline Approach (2023)
    Details
    Publication Date: 2023-11-15
    Description: Droughts can lead to extreme low flow situations in rivers, with resulting severe impacts. Upstream snow and ice melt in many of the world's mountain water towers can alleviate the hydrological consequences of drought, yet global warming threatens the cryosphere. To improve the understanding of melt water contributions during drought in the case of future glacier retreat, we developed stress‐test storyline scenarios to model streamflow and tested them in the European river Rhine basin. Meteorological conditions of past drought and low flow years in Europe, 1976, 2003, and 2018, were repeated at three future moments in time, representing nowadays, near future and far future conditions. The latter two conditions were obtained by climate projections under the RCP8.5 scenario. Results show that the low flow situations caused by the meteorological drought situations aggravate in future conditions, more so for the far future and for the year 2003 because of the relatively large glacier ice melt contribution in the past. Summer (July–September) streamflow may decline by 5%–25% far downstream and 30%–70% upstream and the duration of extreme low flow situations may double compared to the selected past drought events. These results are relevant for the Rhine as a major European river but stand exemplary for many other river basins and highlight the importance of cryospheric changes for downstream low flow situations in a changing climate. The stress‐test scenarios allow a glimpse into future extreme low flow events aiding adaptation planning, and might be adapted to include other important low flow drivers.
    Description: Plain Language Summary: Extended periods with strongly reduced rainfall, in combination with hot summers, lead to accumulating water shortages. As a result, water levels in rivers drop which causes problems, e.g., for shipping, cooling of power plants and drinking and irrigation water supply. During such drought periods, melt water from snow and ice is important for water supply. However, glaciers are projected to further decline in a warming climate, possibly worsen future low flow situations. To quantify this effect, we modeled the amount of water flowing through the Rhine basin (a) for past low flow events in 1976, 2003, and 2018 and (b) for hypothetical situations where we repeat the weather data of those past low flow years at three moments in the future. The results show that flows upstream and downstream in the river Rhine would get even lower in future conditions and cause low flow situations to lengthen considerably. Especially for the year 2003, which had high ice melt contributions in the past, changes are large. In summer, the flow during already critical low flow situations may decrease by up to 70% upstream, and by up to 30% downstream. The results show a glimpse into future low flow events and may help adaptation planning.
    Description: Key Points: A model framework for the Rhine basin was developed to simulate streamflow during extreme past drought years in future conditions. Extreme low flows as in 1976, 2003, and 2018 would aggravate in a future with declined glacier cover and snow pack. Repeating the drought and heatwave of 2003 in the future results in largest reductions in summer streamflow (70% upstream, 30% downstream).
    Description: CHR, International Commission for the Hydrology of the Rhine Basin
    Description: STAY! Scholarship New University Endowment Freiburg
    Description: https://doi.org/10.1002/joc.773
    Description: https://www.geo.uzh.ch/en/units/h2k/Services/HBV-Model/HBV-Download.html
    Description: https://doi.org/10.6094/UNIFR/233644
    Description: https://doi.org/10.6094/UNIFR/226494
    Description: https://doi.org/10.6094/UNIFR/226492
    Description: https://doi.org/10.6094/UNIFR/233639
    Description: https://doi.org/10.1657/1938-4246-46.4.933
    Description: https://doi.org/10.1080/00291957708545328
    Description: https://doi.org/10.3189/172756411799096295
    Keywords: ddc:551.48 ; drought and low flows ; glacier ; upstream‐downstream ; glacio‐hydrological modeling ; Rhine ; stress‐test storylines
    Language: English
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  • 40
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    Insights Into NOx and HONO Chemistry in the Tropical Marine Boundary Layer at Cape Verde During the MarParCloud Campaign (2023)
    Details
    Publication Date: 2023-11-15
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Chemical processing of reactive nitrogen species, especially of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 (= NO + NO〈sub〉2〈/sub〉) and nitrous acid (HONO), determines the photochemical ozone production and oxidation capacity in the troposphere. However, sources of HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 in the remote marine atmosphere are still poorly understood. In this work, the multiphase chemistry mechanism CAPRAM in the model framework SPACCIM was used to study HONO formation at Cape Verde (CVAO) in October 2017, adopted with the input of current parameterizations for various HONO sources. Three simulations were performed that adequately reproduced ambient HONO levels and its diurnal pattern. The model performance for NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 and O〈sub〉3〈/sub〉 improves significantly when considering dust‐surface‐photocatalytic conversions of reactive nitrogen compounds with high correlation coefficients up to 0.93, 0.56, and 0.89 for NO, NO〈sub〉2〈/sub〉, and O〈sub〉3〈/sub〉, respectively. Photocatalytic conversion of the adsorbed HNO〈sub〉3〈/sub〉 on dust is modeled to be the predominant contributor for daytime HONO at CVAO, that is, accounting for about 62% of the chemical formation rate at noontime. In contrast, the ocean‐surface‐mediated conversion of NO〈sub〉2〈/sub〉 to HONO and other discussed pathways are less important. The average OH levels at midday (9:00–16:00) modeled for cluster trajectory 1, 2, and 3 are 5.2, 5.1, and 5.2 × 10〈sup〉6〈/sup〉 molecules cm〈sup〉−3〈/sup〉, respectively. Main OH formation is driven by O〈sub〉3〈/sub〉 photolysis with a contribution of 74.6% to the total source rate, while HONO photolysis is negligible (∼1.8%). In summary, this study highlights the key role of dust aerosols for HONO formation and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 cycling at CVAO and possibly in other dust‐affected regions, urgently calling for further investigations using field and model studies.〈/p〉
    Description: Plain Language Summary: Chemical processing of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 (= NO + NO〈sub〉2〈/sub〉) and nitrous acid (HONO) is important for the tropospheric O〈sub〉3〈/sub〉 budget and oxidation capacity. However, the sources of HONO and cycling of NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 in the remote marine atmosphere are still poorly explored. A detailed multiphase chemistry model simulation showed a better performance of HONO, NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 and O〈sub〉3〈/sub〉 when considering dust‐surface‐photocatalytic conversions of reactive nitrogen compounds, especially the photocatalytic conversion of the adsorbed HNO〈sub〉3〈/sub〉 on dust. The simulations demonstrated that OH formation is mainly driven by the O〈sub〉3〈/sub〉 photolysis, while HONO photolysis is a negligible OH radical source due to its low concentration levels at Cape Verde. The study highlights the key role of dust aerosols for HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 chemistry in the remote marine boundary layer.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉The sources of HONO and NO〈sub〉〈italic〉x〈/italic〉〈/sub〉 at Cape Verde are well modeled with CAPRAM〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Photocatalytic conversion of adsorbed HNO〈sub〉3〈/sub〉 on dust is the predominant contributor for daytime HONO〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Photolysis of O〈sub〉3〈/sub〉 is the prevailing source of OH radical at Cape Verde, while HONO photolysis is a negligible OH radical source〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Leibniz Association SAW
    Description: Horizon 2020 Framework Programme http://dx.doi.org/10.13039/100010661
    Description: National Key Research and Development Program of China http://dx.doi.org/10.13039/501100012166
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: https://doi.org/10.5281/zenodo.8070265
    Description: http://mcm.york.ac.uk/
    Description: https://capram.tropos.de/
    Description: https://ebas.nilu.no/
    Description: https://www.ready.noaa.gov/HYSPLIT_traj.php
    Keywords: ddc:551 ; HONO ; NOx ; CAPRAM ; heterogenous chemistry ; mineral dust ; OH radical ; marine boundary layer
    Language: English
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    The Paleozoic Hydrocarbon System in the Gotland Basin (Central Baltic Sea) Leaks (2023)
    Details
    Publication Date: 2023-11-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Baltic Basin is known for its numerous Paleozoic hydrocarbon reservoirs. There is published evidence that hydrocarbons are leaking from the seafloor, however, little is known about the hydrocarbon migration pathways from Paleozoic source and reservoir rocks toward the seafloor and their escape structures. To investigate these processes, we utilize a new set of multibeam, parametric sediment sub‐bottom profiler and 2D seismic reflection data. The integrated analysis of seismic profiles, diffraction imaging and bathymetric maps allow to identify a hydrocarbon migration system within Silurian and Devonian strata that consists of layer parallel and updip migration beneath sealing layers, migration across seals along faults, and seafloor escape structures in form of elongated depressions. The general migration trend is directed updip, from the Paleozoic reservoirs below the southeastern Baltic Sea toward the Gotland Depression in the northwest. The locations of the hydrocarbon escape structures at the seafloor and their elongated shape are mainly controlled by the regional geological setting of outcropping Paleozoic layers. In addition, iceberg scouring may have facilitated hydrocarbon migration through the Quaternary deposits. The description of this hydrocarbon migration system fills the gap between the known reservoirs and the observed hydrocarbon accumulations and seepages. With regard to potential Carbon Capture and Storage projects, the identification of this hydrocarbon migration system is of great importance, as potential storage sites may be leaking.〈/p〉
    Description: Plain Language Summary: The Baltic Basin including the Baltic Sea is well known for its hydrocarbon reservoirs with ongoing oil production since the 1940s. While there is some published evidence that hydrocarbons are leaking from the seafloor, little is known about the pathways from the reservoirs toward theses leakages. In this study, we use three imaging techniques for the seafloor, the uppermost sediments and the first few kilometers of the subsurface to image the hydrocarbon migration pathways and their escape structures. We find that hydrocarbons are migrating along dipped geological layers from the reservoirs in the southeast toward the Gotland Deep in the northwest. Additionally, we also observe that hydrocarbons are penetrating through these geological layers at locations of pre‐existing small‐scale fractures. The locations, at which the hydrocarbons escape from the seafloor, are mainly controlled by the regional tectonic setting. In addition, iceberg scouring may have had an influence on the exact escape locations. With our findings in this study, we fill the gap between the known reservoirs and the observed seepages and can contribute to questions regarding the potential storage of CO〈sub〉2〈/sub〉 in the Baltic Basin.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Numerous elongated fluid escape depressions are observed at the eastern margin of the Gotland Deep, central Baltic Sea〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉First evidence for fluid migration pathways from Paleozoic toward Quaternary strata in the region〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Locations of fluid escape is controlled by the regional tectonic setting〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.957436
    Description: https://doi.org/10.1594/PANGAEA.956740
    Description: https://doi.org/10.1594/PANGAEA.957422
    Keywords: ddc:622.1 ; seismic interpretation ; diffraction imaging ; Baltic Sea ; fluid migration pathways ; pockmarks ; carbon capture and storage
    Language: English
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    Multispecies assemblages and multiple stressors: Synthesizing the state of experimental research in freshwaters (2023)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-11-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Recent decades have witnessed a sharp biodiversity decline in freshwaters due to multiple stressors. The presence of multiple stressors is expected to affect community structure and interactions in freshwater ecosystems, with subsequent functional consequences. We synthesized the state of experimental, manipulative multiple‐stressor studies that focused on multispecies assemblages in freshwaters. Compared to rivers and lakes, wetland and groundwater ecosystems have received much less attention in identified multiple‐stressor research. Most of the identified studies investigated combinations of abiotic stressors (e.g., nutrients, pesticides, heavy metals, warming, altered flow and sedimentation) on microbes and invertebrates while biotic stressors and vertebrates have been largely overlooked. The responses of community structure (e.g., alpha diversity, biomass, and abundance), some community/ecosystem functions (e.g., photosynthesis and autotrophic activity, leaf litter degradation), and morphological traits like body size and growth forms were frequently investigated. We observed a clear gap in biotic interactions under multiple‐stressor conditions, which, although difficult to study, could impede a deeper mechanistic understanding of how multiple stressors affect freshwater assemblages and associated ecological processes. Although information on ecosystem recovery pathways following restoration is critical for freshwater management, few studies were designed to provide such information, signifying the disconnections between multiple‐stressor research and environmental practice. To bridge these gaps, researchers and environmental practitioners need to work together to identify key stressors and interactions at different spatial and temporal scales and prioritize stressor management. Such collaborations will enhance the translation of multiple‐stressor research into efficient management strategies to protect and restore freshwater ecosystems.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Leibniz‐Gemeinschaft
    Description: German Federal Ministry of Education and Research (BMBF)
    Keywords: ddc:333.95 ; biodiversity ; freshwater ; management ; multiple stressors ; systematic literature review
    Language: English
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  • 43
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    Interpretable Machine Learning Reveals Potential to Overcome Reactive Flood Adaptation in the Continental US (2023)
    Details
    Publication Date: 2023-11-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Floods cause average annual losses of more than US$30 billion in the US and are estimated to significantly increase due to global change. Flood resilience, which currently differs strongly between socio‐economic groups, needs to be substantially improved by proactive adaptive measures, such as timely purchase of flood insurance. Yet, knowledge about the state and uptake of private adaptation and its drivers is so far scarce and fragmented. Based on interpretable machine learning and large insurance and socio‐economic open data sets covering the whole continental US we reveal that flood insurance purchase is characterized by reactive behavior after severe flood events. However, we observe that the Community Rating System helps overcome this behavior by effectively fostering proactive insurance purchase, irrespective of socio‐economic backgrounds in the communities. Thus, we recommend developing additional targeted measures to help overcome existing inequalities, for example, by providing special incentives to the most vulnerable and exposed communities.〈/p〉
    Description: Plain Language Summary: Flood resilience of individuals and communities can be improved by bottom‐up strategies, such as insurance purchase, or top‐down measures like the US National Flood Insurance Program's Community Rating System (CRS). Our interpretable machine learning approach shows that flood insurances are mostly purchased reactively, after the occurrence of a flood event. Yet, reactive behaviors are ill‐suited as more extreme events are expected under future climate, also in areas that were not previously flooded. The CRS counteracts this behavior by fostering proactive adaptation across a widespread range of socio‐economic backgrounds. Future risk management including the CRS should support and motivate individuals' proactive adaptation with a particular focus on highly vulnerable social groups to overcome existing inequalities in flood risk.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Flood insurance purchase in the US is dominated by reactive behavior after severe floods〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The Community Rating System (CRS) fosters proactive insurance adoption irrespective of socio‐economic background〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The CRS should further balance existing inequalities by targeting specific population segments〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: https://api.census.gov/data/2018/acs/
    Description: https://www.fema.gov/about/openfema/data-sets#nfip
    Description: https://www.fema.gov/fact-sheet/community-rating-system-overview-and-participation
    Description: https://msc.fema.gov/portal/home
    Description: https://www.fema.gov/case-study/information-about-community-rating-system
    Description: https://doi.org/10.5281/zenodo.8067448
    Keywords: ddc:363.34 ; FEMA ; machine learning ; flood insurance ; human behavior ; flood resilience
    Language: English
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    Variation of Fault Creep Along the Overdue Istanbul‐Marmara Seismic Gap in NW Türkiye (2023)
    Details
    Publication Date: 2023-12-12
    Description: Strain energy from tectonic loading can be partly released through aseismic creep. Earthquake repeaters, repeatedly activated brittle fault patches surrounded by creep, indicate steady‐state creep that affects the amount of seismic energy available for the next large earthquake along a plate contact. The offshore Main Marmara Fault (MMF) of the North Anatolian Fault Zone represents a seismic gap capable of generating a M 〉 7 earthquake in direct vicinity to the mega‐city Istanbul. Based on a newly compiled seismicity catalog, we identify repeating earthquakes to resolve the spatial creep variability along the MMF during a 15‐year period. We observe a maximum of seismic repeaters indicating creep along the central and western MMF segments tapering off toward the locked onshore Ganos fault in the west, and the locked offshore Princes Islands segment immediately south of Istanbul in the east. This indicates a high degree of spatial creep variability along the Istanbul‐Marmara seismic gap.
    Description: Plain Language Summary: The relative motion of tectonic plates deforms these plates along their contact zone until the plate contact ruptures in an earthquake. However, some of this deformation can be released without earthquakes by so‐called aseismic creep in which the plates creep past each other. Within this creep zone, sometimes some brittle patches exist that interlock during the plate creep and rupture repeatedly in smaller earthquakes that are very similar. They are called earthquake repeaters. In the Sea of Marmara south of Istanbul lies the contact between the Eurasian and the Anatolian plates, the so‐called Main Marmara Fault (MMF). This plate contact did not rupture for a long time and thus a large magnitude event is expected here. We observe a large number of earthquake repeaters in the western offshore part of the MMF while no earthquake repeaters are found toward the east south of Istanbul or onshore toward the west. These areas seem to be locked and might accumulate deformation for a future large earthquake. The zones in between show an intermediate behavior with fewer earthquake repeaters indicating less creep. These results are important for the seismic risk and hazard assessment for the mega‐city of Istanbul.
    Description: Key Points: Earthquake repeaters along the Main Marmara Fault are identified based on a newly derived homogeneous earthquake catalog spanning 15 years. Seismic creep estimated from these repeaters is highly variable along‐strike with higher creep values along the western part. A repeating earthquake sequence showing accelerated activity after a nearby Mw 5.2 earthquake is observed.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: https://doi.org/10.5880/GFZ.4.2.2023.002
    Description: http://doi.org/10.7914/SN/TU
    Description: http://doi.org/10.7914/SN/KO
    Description: http://doi.org/10.7914/SN/PZ
    Description: http://doi.org/10.7914/SN/TB
    Description: http://alomax.free.fr/nlloc/
    Description: https://www.ldeo.columbia.edu/%7Efelixw/hypoDD.html
    Description: http://doi.org/10.5281/zenodo.3407866
    Description: https://doi.org/10.1029/2019gc008515
    Keywords: ddc:551.22 ; repeating earthquakes ; Marmara Sea ; fault creep ; seismic cyle ; seismic gap
    Language: English
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  • 45
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    Revealing the Extent of Submarine Permafrost and Gas Hydrates in the Canadian Arctic Beaufort Sea Using Seismic Reflection Indicators (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Canadian Arctic Southern Beaufort Sea is characterized by prominent relict submarine permafrost and gas hydrate occurrences formed by subaerial exposure during extensive glaciations in Pliocene and Pleistocene. Submarine permafrost is still responding to the thermal change as a consequence of the marine transgression that followed the last glaciation. Submarine permafrost is still underexplored and is currently the focus of several research projects as its degradation releases greenhouse gases that contribute to climate change. In this study, seismic reflection indicators are used to investigate the presence of submarine permafrost and gas hydrates on the outer continental shelf where the base of permafrost is expected to cross‐cut geological layers. To address the challenges of marine seismic data collected in shallow water environments, we utilize a representative synthetic model to assess the data processing and the detection of submarine permafrost and gas hydrate by seismic data. The synthetic model allows us to minimize the misinterpretation of acquisition and processing artifacts. In the field data, we identify features along with characteristics arising from the top and base of submarine permafrost and the base of the gas hydrate stability zone. This work shows the distribution of the present submarine permafrost along the southern Canadian Beaufort Sea region and confirms its extension to the outer continental shelf. It supports the general shape suggested by previous works and previously published numerical models.〈/p〉
    Description: Plain Language Summary: Submarine permafrost, ground beneath the seafloor that perennially remains below 0°C, is present on the continental shelf of the Canadian Beaufort Sea. During the Late Pleistocene (∼1 Million years ago), the continental shelf was subaerially exposed to the cold Arctic air causing the formation of ice in the ground. This period was followed by a sea level rise that flooded the continental shelf with warmer waters, resulting in an intensive change of the thermal regime. The relict permafrost still reacts to this thermal change and is continuously thawing. Associated with the presence of relict permafrost, extensive gas hydrates exist to >1,000 m below the seafloor. Climate warming threatens both the stability of permafrost and associated gas hydrates. Their thawing and decomposition can cause a release of greenhouse gases which in turn amplifies climate warming. This study uses marine seismic reflection data to identify permafrost and gas hydrate in the southern Canadian Beaufort Sea. We find indicators of the top and base of permafrost and the base of the gas hydrate stability zone in the outer continental shelf area. Our work shows that the permafrost and gas hydrates still extend to the outer continental shelf and thereby supports previously published numerical models.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Seismic reflection data reveal occurrences and extent of submarine permafrost and associated gas hydrates at the Canadian Beaufort Shelf〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Synthetic modeling of permafrost and gas hydrate is required to assess seismic processing minimizing the potential for misinterpretation〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Indicators of top and base of permafrost and the base of gas hydrate stability support previously published numerical models〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Korean Ministry of Oceans and Fisheries
    Description: Environmental Geoscience Program of the Geological Survey of Canada
    Description: https://dx.doi.org/doi:10.22663/KOPRI-KPDC-00001958.3
    Keywords: ddc:551 ; submarine permafrost ; gas hydrate ; marine seismic ; Canadian Beaufort Sea ; seismic reflection
    Language: English
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  • 46
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    Exceptions to the temperature–size rule: no Lilliput Effect in end‐Permian ostracods (Crustacea) from Aras Valley (northwest Iran) (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The body size of marine ectotherms is often negatively correlated with ambient water temperature, as seen in many clades during the hyperthermal crisis of the end‐Permian mass extinction (〈italic toggle="no"〉c〈/italic〉. 252 Ma). However, in the case of ostracods, size changes during ancient hyperthermal events are rarely quantified. In this study, we evaluate the body size changes of ostracods in the Aras Valley section (northwest Iran) in response to the drastic warming during the end‐Permian mass extinction at three taxonomic levels: class, order, species. At the assemblage level, the warming triggers a complete species turnover in the Aras Valley section, with larger, newly emerging species dominating the immediate post‐extinction assemblage for a short time. Individual ostracod species and instars do not show dwarfing or a change in body size as an adaptation to the temperature stress during the end‐Permian crisis. This may indicate that the ostracods in the Aras Valley section might have been exceptions to the temperature–size rule (TSR), using an adaptation mechanism that does not involve a decrease in body size. This adaptation might be similar to the accelerated development despite constant instar body sizes that can be observed in some recent experimental studies of ostracod responses to thermal stress.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5061/dryad.xgxd254mb
    Keywords: ddc:565 ; Permian–Triassic ; Ostracoda ; body size ; mass extinction ; Aras Valley section
    Language: English
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  • 47
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    Modern Sedimentation Patterns in Lake Issyk Kul (Kyrgyzstan), Derived From Surface Sediment and Inlet Stream Samples (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This study provides a descriptive characterization of the modern sedimentary processes in Lake Issyk Kul, Kyrgyzstan, important for the selection of a suitable coring or deep‐drilling site, interpretation of future core data and applicability of proxies. The quasi‐equidistant sampling grid of 66 sediment surface samples covers the entirety of the lake basin and is complemented by 10 samples from the major inflows. The methodological approach includes geochemical, granulometric, lipid biomarker, diatom, and statistical analyses. The quantitative and qualitative changes in sediment composition yield information on its generic origin and prevailing transport and depositional environments. The composition of the surface sediments in Issyk Kul is highly heterogenous. Nearshore deposition is mainly controlled by wave action and by fluvial sediment supply with highest quantities of detrital input coming from the high‐energetic, eastern tributaries. Sediments in the deep central basin are mainly produced in situ and dominated by authigenic calcite. Biogenic accumulation is overall low, except for the western extremity of the lake, where the nearshore, shallow‐water, and low‐energetic environment favors aquatic productivity and subsequent preservation of organic material and diatoms. Redeposition of sediments is a dominant process along the slopes across the southern and western basin floor, where run‐out distances of mass movement deposits are up to 5 km. Directional sediment transport by lake currents appears to be less important, except for the transport of very fine‐grained organic matter. Biomarker‐inferred temperature reconstructions suggest lake surface temperatures of ∼15°C in the western littoral zone and in Tyup Bay and a decrease to ∼13°C basinward.〈/p〉
    Description: Plain Language Summary: Intensive research on the natural component of climate variability on geological time scales is needed to better understand and validate current and future climate change. Lakes can provide continuous sediment successions that allow us to reconstruct regional trends in climate and environment dynamics far beyond the industrial age. In continental Eurasia, Lake Issyk Kul, one of the deepest and largest mountain lakes in the world, has long been targeted for a deep‐drilling campaign, because its sediment succession potentially holds information of the past ∼10 million years. Prerequisite for future drilling is a better understanding of prevailing transport and (re)deposition mechanisms in Lake Issyk Kul. The overarching aim of this study is to test the applicability of different proxies, vital for the interpretation of future sediment core data. Therefore, a quasi‐equidistant sampling grid of up to 66 sediment surface (and 10 river) samples spanning the entire lake basin of Lake Issyk Kul was examined by means of sedimentological, geochemical, biological, and statistical analyses. The interpretation provides insights into spatial differences in, for example, clastic input from major rivers, biogenic sedimentation, and endogenic precipitation of calcium carbonates.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉The study provides information on the prevailing transport and (re)deposition mechanisms in Lake Issyk Kul today〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Geochemical, granulometric, lipid biomarker, diatom, and statistical analyses were performed on surface sediment and inlet stream samples〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The results are prerequisite to interpret longer sediment successions from the lake〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.8059855
    Keywords: ddc:551.3 ; Issyk Kul ; modern sedimentary processes ; climate ; geochemistry ; grain‐size ; XRF ; lipid biomarker ; diatoms
    Language: English
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  • 48
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    Bias in Flood Hazard Grid Aggregation (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Reducing flood risk through disaster planning and risk management requires accurate estimates of exposure, damage, casualties, and environmental impacts. Models can provide such information; however, computational or data constraints often lead to the construction of such models by aggregating high‐resolution flood hazard grids to a coarser resolution, the effect of which is poorly understood. Through the application of a novel spatial classification framework, we derive closed‐form solutions for the location (e.g., flood margins) and direction of bias from flood grid aggregation independent of any study region. These solutions show bias of some key metric will always be present in regions with marginal inundation; for example, inundation area will be positively biased when water depth grids are aggregated and volume will be negatively biased when water surface elevation grids are aggregated through averaging. In a separate computational analysis, we employ the same framework to a 2018 flood and successfully reproduce the findings of our study‐region‐independent derivation. Extending the investigation to the exposure of buildings, we find regions with marginal inundation are an order of magnitude more sensitive to aggregation errors, highlighting the importance of understanding such artifacts for flood risk modelers. Of the two aggregation routines considered, averaging water surface elevation grids better preserved flood depths at buildings than averaging of water depth grids. This work provides insight into, and recommendations for, aggregating grids used by flood risk models.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Through a novel framework, we show analytically that hazard grid aggregation leads to bias of key metrics independent of any study region〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉This aggregation is shown to always positively bias inundation area when water depth grids are aggregated〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉For example, aggregating from 1 to 512 m resolution resulted in a doubling of the inundated area for a 2018 flood in Canada〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft
    Description: https://doi.org/10.5281/zenodo.8271996
    Description: https://doi.org/10.5281/zenodo.8271965
    Description: http://geonb.snb.ca/li/index.html
    Description: http://www.snb.ca/geonb1/e/DC/floodraahf.asp
    Keywords: ddc:551.48 ; flood risk ; model scaling ; data aggregation ; flood hazard ; error ; resampling
    Language: English
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  • 49
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    Optimised use of data fusion and memory‐based learning with an Austrian soil library for predictions with infrared data (2023)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Infrared spectroscopy in the visible to near‐infrared (vis–NIR) and mid‐infrared (MIR) regions is a well‐established approach for the prediction of soil properties. Different data fusion and training approaches exist, and the optimal procedures are yet undefined and may depend on the heterogeneity present in the set and on the considered scale. The objectives were to test the usefulness of partial least squares regressions (PLSRs) for soil organic carbon (SOC), total carbon (C〈sub〉t〈/sub〉), total nitrogen (N〈sub〉t〈/sub〉) and pH using vis–NIR and MIR spectroscopy for an independent validation after standard calibration (use of a general PLSR model) or using memory‐based learning (MBL) with and without spiking for a national spectral database. Data fusion approaches were simple concatenation of spectra, outer product analysis (OPA) and model averaging. In total, 481 soils from an Austrian forest soil archive were measured in the vis–NIR and MIR regions, and regressions were calculated. Fivefold calibration‐validation approaches were carried out with a region‐related split of spectra to implement independent validations with n ranging from 47 to 99 soils in different folds. MIR predictions were generally superior over vis–NIR predictions. For all properties, optimal predictions were obtained with data fusion, with OPA and spectra concatenation outperforming model averaging. The greatest robustness of performance was found for OPA and MBL with spiking with 〈italic toggle="no"〉R〈/italic〉〈sup〉2〈/sup〉 ≥ 0.77 (N), 0.85 (SOC), 0.86 (pH) and 0.88 (C〈sub〉t〈/sub〉) in the validations of all folds. Overall, the results indicate that the combination of OPA for vis–NIR and MIR spectra with MBL and spiking has a high potential to accurately estimate properties when using large‐scale soil spectral libraries as reference data. However, the reduction of cost‐effectiveness using two spectrometers needs to be weighed against the potential increase in accuracy compared to a single MIR spectroscopy approach.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4 ; data fusion ; independent validation ; infrared spectroscopy ; MBL ; nitrogen ; outer product analysis ; pH ; soil organic carbon ; spiking ; total carbon
    Language: English
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  • 50
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    Why Membranes Matter: Ion Exchange Membranes in Holistic Process Optimization of Electrochemical CO2 Reduction (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Reducing carbon dioxide to value‐added chemicals by electrolysis is a promising strategy to substitute fossil‐based processes. Research on CO〈sub〉2〈/sub〉 electrolysis has vastly progressed, focusing on catalysis and electrode design, leaving an essential question on the central part of the electrolyzer: Which type of ion exchange membrane is best suited for CO〈sub〉2〈/sub〉 electrolysis from an economic perspective? To address this question, holistic process optimization of CO〈sub〉2〈/sub〉 reduction and product purification is applied. The findings demonstrate that CO〈sub〉2〈/sub〉 electrolysis with an anion exchange membrane shows competitive production costs for CO of 796 €/t〈sub〉CO〈/sub〉, outperforming cation exchange and bipolar membranes. Unlike often described, the CO〈sub〉2〈/sub〉 pumping effect does not significantly impair the economics but offers an efficient indirect regeneration of dissociated CO〈sub〉2〈/sub〉. Furthermore, the results emphasize selective reduction of CO〈sub〉2〈/sub〉 rather than co‐electrolysis of CO〈sub〉2〈/sub〉 and H〈sub〉2〈/sub〉O. While pointing to a positive economic perspective, life‐cycle assessment highlights the need to minimize CO〈sub〉2〈/sub〉 emissions related to electricity consumption and incomplete CO〈sub〉2〈/sub〉 utilization.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Holistic optimization of CO〈sub〉2〈/sub〉 electrolysis and downstream processing highlighted an electrolyzer with an anion exchange membrane to be the most economical for CO production. Interestingly, the CO〈sub〉2〈/sub〉 pumping effect offers an efficient indirect regeneration of dissociated CO〈sub〉2〈/sub〉. Moreover, selective CO〈sub〉2〈/sub〉 reduction is emphasized from economic and ecological assessment, demanding mitigation of CO〈sub〉2〈/sub〉 emissions related to electricity consumption and incomplete utilization. 〈boxed-text position="anchor" content-type="graphic" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:23667486:media:adsu202300077:adsu202300077-gra-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Keywords: ddc:333.7 ; carbon utilization ; electrochemical CO2 reduction ; holistic process optimization ; life‐cycle assessment ; techno‐economic assessment
    Language: English
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    Study of Extreme Magnetopause Distortions Under Varying Solar Wind Conditions (2023)
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉To first order, the magnetopause (MP) is defined by a pressure balance between the solar wind and the magnetosphere. The boundary moves under the influence of varying solar wind conditions and transient foreshock phenomena, reaching unusually large and small distances from the Earth. We investigate under which solar wind conditions such extreme MP distortions occur. Therefore, we construct a database of magnetopause crossings (MPCs) observed by the THEMIS spacecraft in the years 2007 to mid‐2022 using a simple Random Forest Classifier. Roughly 7% of the found crossing events deviate beyond reported errors in the stand‐off distance from the Shue et al. (1998, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1029/98JA01103"〉https://doi.org/10.1029/98JA01103〈/ext-link〉) MP model and thus are termed extreme distortions. We find the occurrence of these extreme events in terms of expansion or compression of the MP to be linked to different solar wind parameters, most notably to the IMF magnitude, cone angle, velocity, Alfvén Mach number and temperature. Foreshock transients like hot‐flow anomalies and foreshock bubbles could be responsible for extreme magnetospheric expansions. The results should be incorporated into future magnetopause models and may be helpful for the reconstruction of the MP locations out of soft x‐ray images, relevant for the upcoming SMILE mission.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉More than 160.000 magnetopause crossings (MPCs) identified in THEMIS data between 2007 and 2022 using a Random Forest Classifier〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Magnetopause crossings that extremely deviate in location from the Shue et al. (1998, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1029/98JA01103"〉https://doi.org/10.1029/98JA01103〈/ext-link〉) model are quite common〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Important solar wind parameters associated with deviations include the interplanetary magnetic field cone angle, solar wind velocity and Alfvén Mach number〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: German Ministerium für Wirtschaft und Klimaschutz and Deutsches Zentrum für Luft‐und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: UKRI Stephen Hawking Fellowship
    Description: German Ministry for Economy and Technology and
    Description: German Center for Aviation and Space
    Description: https://osf.io/b6kux/
    Description: https://github.com/spedas/pyspedas
    Description: http://themis.ssl.berkeley.edu/data/themis/
    Description: https://omniweb.gsfc.nasa.gov/
    Description: https://scikit-learn.org/stable/supervised_learning.html#supervised-learning
    Keywords: ddc:538.7 ; magnetopause ; solar wind ; statistics ; machine learning ; THEMIS
    Language: English
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  • 52
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    Warming and parasitism impair the performance of Baltic native and invasive macroalgae and their associated fauna (2023)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Global warming, bioinvasions, and parasitism affect single‐species performances and species interactions, substantially impacting the structure and stability of marine ecosystems. In light of accelerated global change, the information derived from studies focusing on single species and single drivers is insufficient, calling for a multi‐stressor approach under near‐natural conditions. We investigated the effects of warming (+3°C) on the performance of a benthic community composed of native and invasive macroalgae, consumers and a trematode parasite in a mesocosm setting. We also assessed the effects of warming and parasitism on the survival and growth of gastropods and mussels and the thermal dependency of trematode performance. Our findings show that warming and grazing by infected gastropods had a large detrimental effect on the invasive macroalga growth. Furthermore, the single and interactive effects of parasitism and warming were detrimental to intermediate host survival and growth, especially to large mussels. Finally, cercarial emergence positively correlated to the natural peaks of summer temperatures, while infection intensity in mussels was higher in larger individuals. Our findings suggest that grazing and warming will be detrimental to the invasive macroalga, favoring the native alga. Moreover, parasitism will enhance grazing, especially in summer, when higher temperatures trigger parasite development. However, parasite‐enhanced grazing may be buffered by higher mortality or a shift in the size of infected intermediate hosts under warming. Our findings demonstrate how complex effects of ocean warming can be on food webs and how they can be mediated by parasitism and, as a result, influence native and invasive macroalgae differently.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:577.7 ; Baltic community ; climate change ; bioinvasions ; parasitism ; interactive effects ; macroalgae growth
    Language: English
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  • 53
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    Winter Vertical Diffusion Rates in the Arctic Ocean, Estimated From 7Be Measurements and Dissipation Rate Profiles (2023)
    Details
    Publication Date: 2023-10-26
    Description: Ocean turbulent mixing is a key process affecting the uptake and redistribution of heat, carbon, nutrients, oxygen and other dissolved gasses. Vertical turbulent diffusivity sets the rates of water mass transformations and ocean mixing, and is intrinsically an average quantity over process time scales. Estimates based on microstructure profiling, however, are typically obtained as averages over individual profiles. How representative such averaged diffusivities are, remains unexplored in the quiescent Arctic Ocean. Here, we compare upper ocean vertical diffusivities in winter, derived from the 7Be tracer‐based approach to those estimated from direct turbulence measurements during the year‐long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, 2019–2020. We found that diffusivity estimates from both methods agree within their respective measurement uncertainties. Diffusivity estimates obtained from dissipation rate profiles are sensitive to the averaging method applied, and the processing and analysis of similar data sets must take this sensitivity into account. Our findings indicate low characteristic diffusivities around 10〈sup〉−6〈/sup〉 m〈sup〉2〈/sup〉 s〈sup〉−1〈/sup〉 and correspondingly low vertical heat fluxes.
    Description: Plain Language Summary: Ocean turbulent mixing plays an important role in the uptake and redistribution of heat, carbon, nutrients, oxygen and other properties. For example, this process delivers nutrients to the sunlit surface ocean where they are utilized to produce plants (phytoplankton) for the ecosystem food web. However, strong changes in density within the upper Arctic Ocean hinder vertical transport of nutrients, such that nutrient fluxes are generally smaller than those observed elsewhere in the world ocean. Furthermore, low vertical transport rates isolate the surface ocean from heat input from below which helps protect the ice from melting. Here, we compare the strength of upper ocean mixing, an important parameter for the calculation of vertical transport, derived from two independent methods during the MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) ice drift experiment, 2019–2020. This comparison allows us to better quantify the vertical diffusivity, and in turn also the vertical transport of for example, heat and nutrients in the ocean.
    Description: Key Points: Arctic Ocean vertical diffusivity (K〈sub〉z〈/sub〉) in the upper halocline in winter is O(10〈sup〉−6〈/sup〉) m〈sup〉2〈/sup〉 s〈sup〉−1〈/sup〉. Diffusivity estimates from 〈sup〉7〈/sup〉Be measurements and ocean microstructure profiling agree within a factor of 2. K〈sub〉z〈/sub〉 estimates from turbulent dissipation rate profiles are sensitive to the averaging method.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Research Council of Norway
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.1594/PANGAEA.939816
    Description: https://doi.org/10.26008/1912/bco-dmo.861596.1
    Keywords: ddc:551.46 ; Arctic Ocean ; vertical mixing ; halocline ; winter ; turbulent diffusivity ; microstructure profiling
    Language: English
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  • 54
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    Formation of Thermochemical Heterogeneities by Core‐Mantle Interaction (2023)
    Details
    Publication Date: 2023-10-26
    Description: Earth's core‐mantle boundary (CMB) shows a complex structure with various seismic anomalies such as the large low shear‐wave velocity provinces (LLSVPs) and ultra‐low velocity zones (ULVZs). As these structures are possibly induced by chemically distinct material forming a layer above the CMB, models of mantle convection made ad hoc assumptions to simulate the dynamics of this layer. In particular, density and mass were prescribed. Both conditions are critical for the dynamics but hardly constrained. Core‐mantle interaction is considered as one possible origin for this dense layer. For example, diffusion‐controlled enrichment of iron has been proposed. We here apply a chemical gradient between the mantle and the denser core to analyze the penetration of dense material into the mantle. As such, we employ 2D Cartesian models where a thermochemical layer at the base of the mantle develops self‐consistently by a diffusive chemical influx. Our simulations indicate that chemical diffusion is strongly affected by the convective mantle flow. This convection‐assisted diffusion yields a compositional influx mainly in the areas where slabs spread over the bottom boundary and sweep dense material aside to form accumulations with rising plumes atop. Like for a prescribed dense layer this process leads to chemically distinct piles, which are typically smaller (therefore more suited to explain ULVZs) but more persistent due to the constant chemical influx. Combining the influx scenario with the primordial layer can possibly explain the simultaneous existence of LLSVPs and ULVZs along with the observation of a core‐like isotopic composition in the mantle.
    Description: Plain Language Summary: The core‐mantle boundary (CMB) shows a complex structure. Seismologists have observed features that are possibly denser than their surroundings. These structures form from a dense layer above the CMB. Therefore typical mantle convection models have assumed an initial dense basal layer. The thickness and density of this prescribed layer are crucial but hardly constrained. Here we investigate core‐mantle interaction as one possible origin for this layer and employ 2D Cartesian models of mantle convection that consider a diffusive chemical gradient between the iron‐rich core and the silicate mantle. Our simulations show that the diffusive influx is coupled to the convective mantle flow. Convection‐assisted diffusion gives a larger influx beneath slabs spreading over the CMB. Additionally, as in the models with a prescribed layer, the rising plumes pull dense material up and form piles. In this study, however, the constant chemical influx leads to piles existing for longer times. The piles are typically smaller but can maybe in combination with a primordial layer explain different seismologically observed structures and the presence of core material in the mantle.
    Description: Key Points: We analyze convection‐assisted core‐mantle interaction in thermochemical mantle convection models. Dense material penetrates into the mantle as a result of a basal diffusive chemical influx, where penetration is promoted by convection. Small piles form with some of the dense core material being entrained by plumes.
    Description: Deutsche Forschungsgemeinschaft
    Description: https://doi.org/10.1080/03091929608208968
    Description: https://doi.org/10.1002/2015GC005807
    Description: https://doi.org/10.35003/JENO4T
    Keywords: ddc:551.1 ; core‐mantle interaction ; mantle convection ; LLSVPs ; ULVZs
    Language: English
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    Planetary Impacts: Scaling of Crater Depth From Subsonic to Supersonic Conditions (2023)
    Details
    Publication Date: 2023-10-26
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Planetary impacts have shaped the surfaces and interiors of planets. They were particularly critical in the last stage of planetary accretion, as they have eventually formed terrestrial planets. During these large supersonic collisions, shock waves melted the impactor and the target, and formed silicate magma oceans. Because the propagation of shock waves and the melting is faster than the excavation of an impact crater, the cratering stage can be considered as a purely hydrodynamic process. Here, we use both laboratory impact experiments in water and numerical simulations to investigate the crater dimensions resulting from the impact of a liquid impactor onto a liquid target. We show that our numerical models reproduce the laboratory experiments at subsonic impact velocities. We then explore the effect of both the Froude number, which is the ratio of the impactor kinetic energy to gravity, and the Mach number, which is the ratio of the impact speed to the sound speed. We vary these two parameters independently in impact simulations, going from subsonic to supersonic conditions. We obtain a new scaling law for the crater dimensions that describes the transition from subsonic to supersonic impacts. Our results indicate that the transition between these two regimes results from a change in the partitioning of the impactor kinetic energy into potential energy in the crater and internal energy. Finally, our scaling suggests that, in the limit of large Mach numbers, the crater depth depends only on the sound velocity and gravity, and is independent of the impact speed.〈/p〉
    Description: Plain Language Summary: Planetary formation involved a large number of very energetic collisions. Such impacts generated shock waves which led to widespread melting and the formation of magma oceans. Understanding the dynamics of impacts into magma oceans is of great importance as these collisions set the initial temperature and composition of terrestrial planets and satellites. Laboratory experiments and numerical simulations have been used to investigate large impacts. However, each approach has pros and cons. Liquid impact experiments can produce the small scales responsible for the mixing between the impactor and the target, but they fail to reproduce shock waves and supersonic speeds. In contrast, current numerical simulations reach supersonic conditions but produce a limited amount of turbulence and mixing. In this study, we bridge the gap between these two methods and improve our understanding of the effect of the impact velocity on the cratering process. Using the code iSALE, we numerically reproduce water impact experiments at low subsonic velocities. We then explore supersonic conditions in impact simulations. We obtain a new scaling law predicting the crater depth in more realistic impact conditions and show that it is limited only by the sound speed for large impact velocities.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉The shock physics code iSALE is successfully benchmarked against subsonic water impact experiments〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉A scaling law is proposed for the crater depth as a function of the Mach and Froude numbers which are varied as independent parameters〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉In the limit of high Mach numbers, our scaling suggests that the maximum crater depth is controlled by the sound velocity and gravity, but not by the impact speed〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: DFG
    Description: EPSRC
    Description: National Aeronautics and Space Administration
    Description: NSF Physics Frontier Center
    Description: Programme National de Planétologie
    Description: CNES
    Description: Alfred P. Sloan Foundation
    Description: https://isale-code.github.io/
    Keywords: ddc:523 ; impact cratering ; pi‐scaling ; magma ocean ; scaling laws ; fluid dynamics
    Language: English
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    Investigation of a Dissipating Mesospheric Bore Using Airglow Imager and Direct Numerical Simulation (2023)
    Details
    Publication Date: 2023-10-26
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Atmospheric gravity waves play an important role in driving the dynamics of the Mesosphere and Lower Thermosphere and the basic structure of this region is determined by momentum deposition of these waves. Mesospheric bores are a type of non‐linear response that cause the amplification of gravity wave, due to trapping, that is characterized by a propagating step‐like jump followed by undulating waves. They require a stable layer or duct to travel horizontally with little attenuation thereby capable of transporting wave energy and momentum over larger distances. We present a prominent bright undular bore event observed in the mesospheric O(〈sup〉1〈/sup〉S), O〈sub〉2〈/sub〉, and OH emission layers on 16 March 2021 over Germany. A striking feature of this observation is the capture of bore's rapid dissipation around the center of the imager's field of view. The vertical temperature profile obtained from the satellite data indicates the presence of temperature inversion layer which acted as a thermal duct for the bore propagation. In addition, we have performed idealized two dimensional direct numerical simulations (DNS) of Navier‐Stokes equations under Boussinesq approximation. The DNS results reproduce many important characteristics of the observed airglow event like the nonlinear wave‐steepening, number of trailing waves, and its dissipation by implementing a thermal duct and a wave‐like perturbation. Furthermore, the DNS results also indicate that the duct width and amplitude of the initial perturbation have a considerable effect on the bore morphology.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Observation of a mesospheric bright bore event that dissipated within the field of view〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The duct that enabled the bore propagation was near the O(〈sup〉1〈/sup〉S) emission layer based on the observational data〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The majority of the observed features are reproduced with idealized 2D direct numerical simulations using Boussinesq approximation〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: https://doi.org/10.22000/809
    Description: http://sirius.bu.edu/data/
    Description: http://saber.gats-inc.com/coin.php
    Keywords: ddc:551.5 ; bores ; direct numerical simulations ; gravity waves ; inversion layers
    Language: English
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    Report on continental-scale high-resolution modeling of streamflow intermittence (2023)
    Details
    Publication Date: 2023-10-31
    Description: Quantification of the temporally varying streamflow intermittence at continental scales provides an important basis for evaluating biodiversity, ecosystem functions and ecosystem services in rivers as well as water resources for humans. As streamflow intermittence is often more prevalent in small upstream river reaches than in large downstream rivers, quantification needs to be done with a high spatial resolution. Aggregated to five classes (0, 1-2, 3-15, 16-29, 30-31 no-flow days), the number of no-flow days of approximately 1.5 million river reaches in Europe was estimated for each of the 468 months in the period 1981-2019 using a two-step Random Forest modeling approach. The model was developed based on a custom version of the 15 arc-sec HydroSHEDS drainage direction dataset. Data for 18 predictor variables (on hydrology, climate, physiography, geology, and land cover) as well as daily streamflow observed at 1,915 streamflow gauging stations were prepared as input to the RF model. In addition to upstream drainage area and slope, predictors based on time series of streamflow in 15 arc-sec grid cells were found to be most important for the RF model. These time series were generated by downscaling the 0.5 arc-deg runoff of the global hydrological model WaterGAP (downscaled streamflow is also already available for South America). In Europe but not in South America, the performance of downscaled monthly WaterGAP v2.2e streamflow as compared to streamflow observations is, on average, satisfactory also for small drainage basins of less than 10 km2. While 99% and 95% of the observed perennial station-months are predicted correctly for the calibration and validation periods, respectively, the RF approach tends to overestimate intermittence Considering only the intermittent station-months, the frequency of predicting the correct class among the four classes is about 56% and 47% for the calibration and the validation period, respectively. 9% of all reach-months are simulated to be intermittent. The temporal and spatial patterns of simulated intermittence classes are plausible. The simulated intermittence class in each reach-month will be used by the other DRYvER Work Packages to upscale models developed at the Drying River Network scale.
    Description: report
    Keywords: Streamflow ; Random Forest ; Downscaling ; No-flow days ; Streamflow intermittence ; Continental scale
    Language: English
    Type: doc-type:book
    Format: 59
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    Oxygen Dependent Temperature Regulation of Benthic Fluxes in Reservoirs (2023)
    Details
    Publication Date: 2023-12-16
    Description: Temperature and dissolved oxygen concentration are critical factors affecting the exchange of solutes between sediment and water; both factors will be affected by warming of lakes and thereby influence water quality. Temperature and oxygen responses of single solute fluxes are well known; however, not much is known about the interaction of temperature and oxygen in regulating the balance of different fluxes in the benthic environment. We analyzed benthic flux (mobilization and immobilization) data of various solutes (dissolved organic carbon (DOC), CH〈sub〉4〈/sub〉, NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉‐N, NH〈sub〉4〈/sub〉+〈/sup〉‐N, SRP, SO〈sub〉4〈/sub〉〈sup〉−〈/sup〉, Fe, Mn, and O〈sub〉2〈/sub〉) collected from laboratory incubations of 142 sediment cores from 5 different reservoirs incubated under varying in situ temperature and oxygen conditions. Oxygen was the primary driver of benthic fluxes, while temperature and total organic content were secondary. Temperature effects on benthic fluxes were stronger under anoxic conditions which imply that warming will substantially increase the benthic fluxes if the sediment surface becomes anoxic. The varying temperature response of processes underlying the studied fluxes will result in a shift of their relative importance in the benthic environment, especially in shallow lakes that are more vulnerable to warming. For example, more anoxic conditions will shift the equilibrium between net sulfate reduction and methane release toward the latter. We also predict that physical effects of warming leading to hypolimnetic oxygen depletion, that is, stronger stratification and longer hypolimnetic confinement will increase the benthic mobilization of phosphorus, DOC, and methane into water and immobilization of sulfate by the sediments even in deep lakes.
    Description: Plain Language Summary: Temperature and dissolved oxygen concentration control the release of undesirable components buried in lake or reservoir sediments, that is, nutrients, metals, and organic matter, which can cause water quality problems. We investigated the effects of rising temperature and levels of oxygen on the release of undesirable components by performing experiments using sediments and water from five different reservoirs. The sediments with a layer of water on top were incubated under different in situ temperature (low and high) and oxygen conditions (with and without). Our results show that the absence of oxygen was the main cause of the release of nutrients and metals. When there was no oxygen in the sediment and water, nutrients and metals were released from the sediment into the water and this effect increased when temperature was high. There is higher possibility that phosphorus, dissolved organic carbon, and methane will be released from sediments in some reservoirs as a result of global warming.
    Description: Key Points: Solute fluxes from benthic lake sediments varied in response to temperature, with oxygen fluxes responding most strongly. Temperature effects on the magnitude of benthic fluxes were stronger under anoxic than oxic conditions. Direct temperature effects on reservoir water quality will be small compared to indirect effects through anoxia facilitation.
    Description: German Federal Ministry of Education and Research
    Description: MINECO
    Description: https://doi.pangaea.de/10.1594/PANGAEA.928570
    Keywords: ddc:551 ; temperature dependency ; oxygen ; benthic fluxes ; reservoirs ; anoxia ; activation energy
    Language: English
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    The Mini Induced Magnetospheres at Mars (2023)
    Details
    Publication Date: 2023-12-16
    Description: We report on observations made by the Mars Atmosphere and Volatile EvolutioN spacecraft at Mars, in the region of the ion plume. We observe that in some cases, when the number density of oxygen ions is comparable to the density of the solar wind protons interaction between both plasmas leads to formation in the magnetosheath of mini induced magnetospheres possessing all typical features of induced magnetospheres typically observed at Mars or Venus: a pileup of the magnetic field at the head of the ion cloud, magnetospheric cavity, partially void of solar wind protons, draping of the interplanetary magnetic field around the mini obstacle, formation of a magnetic tail with a current sheet, in which protons are accelerated by the magnetic field tensions. These new observations may shed a light on the mechanism of formation of induced magnetospheres.
    Description: Plain Language Summary: There is a class of the induced planetary magnetospheres when the absence of intrinsic magnetic field allows a direct interaction of solar wind with planetary atmospheres/ionospheres. We have shown the existence of mini‐induced magnetospheres at Mars. When the density of the extracted from the ionosphere oxygen ions becomes comparable with the proton density in solar wind mini‐induced magnetospheres with all typical features of the planetary induced magnetospheres arise.
    Description: Key Points: Oxygen ions extracted from the Martian ionosphere interact with shocked solar wind in the magnetosheath. When the ion densities of both plasmas become comparable the mini induced magnetospheres are built. These Magnetospheres possess all typical features of the classical induced magnetospheres.
    Description: NASA
    Description: DFG
    Description: https://pds-ppi.igpp.ucla.edu/mission/MAVEN/MAVEN/MAG
    Description: https://pds-ppi.igpp.ucla.edu/mission/MAVEN/MAVEN/STATIC
    Keywords: ddc:523 ; Mars ; solar wind ; induced magnetosphere ; ionosphere ; magnetic barrier ; magnetic tail
    Language: English
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    Advances in New Zealand's Tephrochronostratigraphy Using Marine Drill Sites: The Neogene (2023)
    Details
    Publication Date: 2023-12-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Three volcanic arcs have been the source of New Zealand's volcanic activity since the Neogene: Northland arc, Coromandel Volcanic Zone (CVZ) and Taupō Volcanic Zone (TVZ). The eruption chronology for the Quaternary, sourced by the TVZ, is well studied and established, whereas the volcanic evolution of the precursor arc systems, like the CVZ (central activity c. 18 to 2 Ma), is poorly known due to limited accessibility to, or identification of, onshore volcanic deposits and their sources. Here, we investigate the marine tephra record of the Neogene, mostly sourced by the CVZ, of cores from IODP Exp. 375 (Sites U1520 and U1526), ODP Leg 181 (Sites 1123, 1124 and 1125), IODP Leg 329 (Site U1371) and DSDP Leg 90 (Site 594) offshore of New Zealand. In total, we identify 306 primary tephra layers in the marine sediments. Multi‐approach age models (e.g. biostratigraphy, zircon ages) are used in combination with geochemical fingerprinting (major and trace element compositions) and the stratigraphic context of each marine tephra layer to establish 168 tie‐lines between marine tephra layers from different holes and sites. Following this approach, we identify 208 explosive volcanic events in the Neogene between c. 17.5 and 2.6 Ma. This is the first comprehensive study of New Zealand's Neogene explosive volcanism established from tephrochronostratigraphic studies, which reveals continuous volcanic activity between c. 12 and 2.6 Ma with an abrupt compositional change at c. 4.5 Ma, potentially associated with the transition from CVZ to TVZ.〈/p〉
    Description: Plain Language Summary: Since 18 Ma, volcanic activity in New Zealand is dominantly sourced by the Coromandel Volcanic Zone (CVZ). Most caldera systems of the CVZ identified so far are located on Coromandel Peninsula in the NW of North Island, New Zealand, but studies of the CVZ are rare mainly due to the limited accessibility of its volcanic deposits, as well as missing stratigraphic continuity between different outcrops and the volcanic source. Here, our ocean drilling tephra record—mainly volcanic ash from explosive eruptions, distributed and falling out over the ocean—has a great potential to reveal the eruption history of the CVZ because it is preserved in marine sediments in a nearly undisturbed stratigraphic context. We analyzed ∼400 marine tephra layers from multiple ocean sediment cores off the coast of New Zealand for their geochemical glass compositions and identified 306 as largely undisturbed ash deposits. These primary ash deposits correspond to a total number of 208 Neogene volcanic events. Different dating methods result in a continuous marine tephra record for the last 12 Ma, equivalent to a unique and most complete eruptive history for the CVZ. This enables us to further unravel changes in the composition of the associated magmas with time.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉New Zealand's Neogene explosive volcanism based on the marine tephra record〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Geochemical fingerprinting of marine tephra layers across the study area to establish volcanic events〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Insights into geochemical variations with time, repose times and spatiotemporal distribution〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: DFG
    Description: Marsden project
    Description: https://doi.org/10.14379/iodp.proc.372B375.210.2023
    Keywords: ddc:551 ; marine tephrochronostratigraphy ; geochemical fingerprinting ; correlations of marine tephras between individual drill sites ; IODP ; ODP and DSDP drill sites ; neogene eruption record of New Zealand
    Language: English
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    European Summer Synoptic Circulations and Their Observed 2022 and Projected Influence on Hot Extremes and Dry Spells (2023)
    Details
    Publication Date: 2023-12-16
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In 2022, western Europe experienced its hottest summer on record and widespread dry conditions, with substantial impacts on health, water and vegetation. We use a reanalysis to classify daily mean sea level pressure fields and to investigate the influence of synoptic circulations on the occurrence of temperature extremes and dry days. Summer 2022 featured an above‐normal occurrence of anticyclones extending from the British Isles to the Baltic countries, as well as enhanced easterly, southerly and low‐flow conditions which contributed to the observed extremes over southern and western Europe. While the hot summer of 2022 is only partially explained by circulation anomalies, such anomalies played a key role in the exceptional occurrence of dry days. The comparison with summer circulation anomalies projected by twenty global climate models moreover suggests that future circulation changes will further exacerbate hot and dry extremes over Europe.〈/p〉
    Description: Plain Language Summary: In 2022, western Europe recorded its hottest summer up to date since preindustrial times. At the same time, widespread dry conditions caused dramatic impacts on human health, water resources, crop yields and wildfires. This was partly enhanced by the human–caused cumulative emissions of greenhouse gases, but also potentially by large‐scale circulation anomalies that may also be triggered by global warming. By grouping distinct weather patterns, we find that many extreme hot days during the summer of 2022 over well‐defined parts of Europe were favored by anomalous transport of hot and dry air masses or persistent low‐wind conditions. These weather patterns were essential but not the dominant factor that led to the occurrence of extreme temperatures. Yet, they played a key role in enhancing the number of dry days. We also find that the weather patterns observed in summer 2022 will become more common in coming decades if greenhouse gas emissions remain without reduction. This would further worsen hot and dry extremes in summer over Europe.〈/p〉
    Description: Key Points : 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉European summer 2022 hot extremes have been enhanced by an anomalous occurrence of distinct circulation types over different subdomains〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Predominant circulation anomalies also contributed to the exceptional number of dry days, as much as local, mostly thermodynamical effects〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Such anomalous circulations will become more common, thus further worsening European hot and dry extremes〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: HORIZON EUROPE Marie Sklodowska‐Curie Actions http://dx.doi.org/10.13039/100018694
    Description: https://doi.org/10.24381/cds.adbb2d47
    Description: https://doi.org/10.5194/gmd-9-1937-2016
    Keywords: ddc:551.6 ; hot summer 2022 ; hot extremes ; circulation types ; circulation classification ; climate change ; atmospheric circulation
    Language: English
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    Timing and Origin of Compressional Tectonism in Mare Tranquillitatis (2023)
    Details
    Publication Date: 2023-12-15
    Description: The lithosphere of the Moon has been deformed by tectonic processes for at least 4 billion years, resulting in a variety of tectonic surface features. Extensional large lunar graben formed during an early phase of net thermal expansion before 3.6 Ga. With the emplacement of mare basalts at ∼3.9–4.0 Ga, faulting and folding of the mare basalts initiated, and wrinkle ridges formed. Lunar wrinkle ridges exclusively occur within the lunar Maria and are thought to be the result of superisostatic loading by dense mare basalts. Since 3.6 Ga, the Moon is in a thermal state of net contraction, which led to the global formation of small lobate thrust faults called lobate scarps. Hence, lunar tectonism recorded changes in the global and regional stress fields and is therefore an important archive for the thermal evolution of the Moon. Here, we mapped tectonic features in the non‐mascon basin Mare Tranquillitatis and classified these features according to their respective erosional states. This classification aims to provide new insights into the timing of lunar tectonism and the associated stress fields. We found a wide time range of tectonic activity, ranging from ancient to recent (3.8 Ga to 〈50 Ma). Early wrinkle ridge formation seems to be closely related to subsidence and flexure. For the recent and ongoing growth of wrinkle ridges and lobate scarps, global contraction with a combination of recession stresses and diurnal tidal stresses, as well as with a combination of South Pole‐Aitken ejecta loading and true polar wander are likely.
    Description: Plain Language Summary: The lithosphere of the Moon has been deformed by tectonic processes for at least 4 billion years, resulting in a variety of tectonic surface features. Simple compressional asymmetric landforms are called lobate scarps and complex compressional features, which form as a result of the combination of faulting and folding, are known as wrinkle ridges. Lunar wrinkle ridges only occur within the lunar Maria. It has been argued that their formation is linked to the subsidence of the dense mare basalts, which would have happened in the early history of the Moon. We mapped all of these features within a dark lunar region called Mare Tranquillitatis and then studied their morphology on high‐resolution images. Based on their morphology, we found a wide time range of tectonic activity, ranging from ancient to recent. Large wrinkle ridges seem to be ancient and influenced by subsidence. Smaller wrinkle ridges and lobate scarps show signs of recent activity. They likely formed recently within the last hundred million years because of the Moon's current state of global compression.
    Description: Key Points: Early compressional tectonism in Tranquillitatis, in the form of wrinkle ridges, is presumably related to subsidence and basin loading. Later tectonism could reflect the evolution from a basin‐localized to a global stress field and the continued growth of ancient faults. Recent wrinkle ridge and lobate scarp formation in Tranquillitatis occurred in the last 50 Ma and is influenced by a global stress field.
    Description: https://doi.org/10.5281/zenodo.7551409
    Description: https://darts.isas.jaxa.jp/planet/pdap/selene/
    Description: https://doi.org/10.17189/1520341
    Description: http://imbrium.mit.edu/DATA/SLDEM2015
    Description: https://doi.org/10.17189/1519529
    Description: https://quickmap.lroc.asu.edu/
    Description: http://www.yongtechnology.com/download/georose
    Keywords: ddc:523 ; Moon ; tectonics ; wrinkle ridges ; lobate scarps ; lithosphere ; tectonic mapping
    Language: English
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    One Geoscience: Providing FAIR global Access to all Geoscience Data -are we there yet? (2023)
    Details
    Publication Date: 2023-12-13
    Description: Geoscience deals with all fields of natural science related to understanding past, current and future states of the Earth and the terrestrial bodies. Geoscience has many sub-disciplines that have strong roots in other sciences such as chemistry, physics, geography, biology and mathematics. Each sub-discipline generally works in isolation and is governed by different science unions, societies and associations. Datasets generated by each are diverse, complex and heterogeneous: few fully comply with the FAIR principles. Hence it is hard to integrate datasets both within and across each sub-discipline. To enable efficient integration of geoscience data to effectively contribute to societal grand challenges will require conformance to agreed international standards and compliance with FAIR. The first attempt at international digital integration of data within one of these sub-disciplines was OneGeology, which in 2008 harmonised geological map data globally. More recently, OneGeochemistry is emerging as a fledgling effort to unify geochemical data across multiple sample types and analytical techniques in the geochemical domain. Geophysicists have not yet taken up the call for OneGeophysics but the potential is there. Rather than developing standards completely within each sub-discipline, a more holistic approach is to leverage the Observation, Measurement and Samples (OMS) Standard (IS0 19156: 2023) and break down the standards and vocabularies required into modules based around the feature of interest, instrument, procedures, event, place, properties value, result, etc. This presentation will highlight potential ways to use OMS to accelerate development and convergence of standards and vocabularies required to enable OneGeoscience to become a reality.
    Description: presentation
    Keywords: research data management ; data standards ; FAIR Principles ; interoperability
    Language: English
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    Interactions of Hydraulic Fractures With Grain Boundary Discontinuities in the Near Wellbore Region (2023)
    Details
    Publication Date: 2023-12-14
    Description: Hydraulic fractures often turn or branch, interacting with preexisting discontinuities in the rock mass (e.g., natural fractures or defects). The criteria for fracture penetration or deflection are typically based on the in situ stress, and the angle and strength of discontinuities. However, in hydraulic fracture experiments on carbonate rocks (Naoi et al., 2020, https://doi.org/10.1093/gji/ggaa183), small scale analyses show that the fractures deflected more frequently at discontinuities (grain boundaries) as they propagated farther from the wellbore, a finding not explained by the conventional criteria. Here, we demonstrate that the energy dissipation of a deflecting fracture increases with the distance from the wellbore, such that a propagating hydraulic fracture more easily deflects at a discontinuity from an energetic standpoint. This tendency was confirmed by hydraulic fracture simulations based on a successive energy minimization approach. Our findings, which show that wellbores appreciably affect the behavior of hydraulic fractures, highlight the importance of energetic stability analysis for determining fracture paths.
    Description: Plain Language Summary: Hydraulic fractures may form complex patterns as they grow outward from a wellbore by turning or deflecting when they interact with preexisting discontinuities in rocks. Because complex fractures enhance the permeability of rock formations more effectively than planar fractures, many studies have investigated how a fracture interacts with a preexisting discontinuity such as a natural fracture. The fate of a growing fracture at a discontinuity—whether it penetrates or deflects—is typically judged based on the in situ subsurface stress, and the characteristics of the discontinuity. However, we observed in experiments that fractures deflected more often at discontinuities (grain boundaries) as they propagated farther away from the wellbore, which cannot be explained by the conventional criteria. To explain these observations, we analyzed the energy expenditure of a deflecting fracture and showed that it becomes energetically more favorable for a fracture to deflect at a discontinuity as it grows farther away from the wellbore. We confirmed this insight by using numerical simulations. We thus caution that the conventional criteria may not be applicable in the near wellbore region, and we suggest that energetic stability, rather than the local stress at the fracture tip, should be analyzed to determine fracture paths.
    Description: Key Points: Experimental results show that hydraulic fractures deflect more frequently at grain boundaries with increasing distance from the wellbore. Numerical analyses demonstrate that energy dissipation increases with the distance from the wellbore, consistent with our experimental findings. Criteria for fracture deflection/penetration based on the in situ stress and fracture geometry may not apply to near wellbore regions.
    Description: Japan Organization for Metals and Energy Security
    Description: https://www.opengeosys.org/
    Description: https://doi.org/10.5281/zenodo.6390977
    Description: https://doi.org/10.5281/zenodo.6811452
    Keywords: ddc:550.724 ; fracture interaction ; fracture energy ; hydraulic fracture
    Language: English
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    Toward Large‐Scale Soil Moisture Monitoring Using Rail‐Based Cosmic Ray Neutron Sensing (2023)
    Altdorff, Daniel ; Oswald, Sascha E. ; Zacharias, Steffen ; [et al.]
    Details
    Publication Date: 2023-12-14
    Description: Cosmic ray neutron sensing (CRNS) has become a promising method for soil water content (SWC) monitoring. Stationary CRNS offers hectare‐scale average SWC measurements at fixed locations maintenance‐free and continuous in time, while car‐borne CRNS roving can reveal spatial SWC patterns at medium scales, but only on certain survey days. The novel concept of a permanent mobile CRNS system on rails promises to combine the advantages of both methods, while its technical implementation, data processing and interpretation raised a new level of complexity. This study introduced a fully automatic CRNS rail‐borne system as the first of its kind, installed within the locomotive of a cargo train. Data recorded from September 2021 to July 2022 along an ∼9 km railway segment were analyzed, as repeatedly used by the train, supported by local SWC measurements (soil samples and dielectric methods), car‐borne and stationary CRNS. The results revealed consistent spatial SWC patterns and temporary variation along the track at a daily resolution. The observed variability was mostly related to surface features, seasonal dynamics and different responses of the railway segments to wetting and drying periods, while some variations were related to measurement uncertainties. The achieved medium scale of SWC mapping could support large scale hydrological modeling and detection of environmental risks, such as droughts and wildfires. Hence, rail‐borne CRNS has the chance to become a central tool of continuous SWC monitoring for larger scales (≤10‐km), with the additional benefit of providing root‐zone soil moisture, potentially even in sub‐daily resolution.
    Description: Key Points: The first rail‐borne Cosmic ray neutron sensing system for automatic and continuous soil water content monitoring at the hectare scale is presented. The system provided almost uninterrupted data from September 2021 to July 2022 along a 9 km railway track in the Harz low mountains, Germany. Results showed spatial pattern, related to surface features, seasonal change, and individual responses of railway parts to wetting and drying.
    Description: Helmholtz Centre for Environmental Research GmbH
    Description: Havelländische Eisenbahn Gesellschaft
    Description: Deutsche Forschungsgemeinschaft
    Description: Modular Observation Solutions for Earth Systems
    Description: Terrestrial Environmental Observatories in Germany
    Description: https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/O1MHKR
    Description: http://www.nmdb.eu/
    Keywords: ddc:622.15 ; continuous soil moisture monitoring ; soil moisture products ; hydrological observations ; automatic geophysical roving ; root zone soil water ; time‐series soil water content mapping
    Language: English
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    Effects of Global Geomagnetic Field Variations Over the Past 100,000 Years on Cosmogenic Radionuclide Production Rates in the Earth's Atmosphere (2023)
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The production rates of cosmogenic radionuclides, such as 〈sup〉10〈/sup〉Be, 〈sup〉14〈/sup〉C, and 〈sup〉36〈/sup〉Cl, in the Earth's atmosphere vary with the geomagnetic field and solar activity. For the first time, the production rates of several cosmogenic nuclides are estimated for the past 100 ka based on global, time‐dependent geomagnetic field models and a moderate solar‐activity level. In particular, the production rates were high with no notable latitudinal dependence during the Laschamps geomagnetic excursion (41 ka BP). The mean global production of 〈sup〉10〈/sup〉Be over the Laschamps excursion was more than two times greater than the present‐day one, whereas the increase was 1.9 times for the Norwegian‐Greenland Sea excursion (∼65 ka), and only 1.3 times for the Mono Lake/Auckland excursion (∼34 ka). All analyzed geomagnetic field models covering the past 100 ka, including the modern and Holocene epochs, lead to hemispheric asymmetry in the production rates, persistent overall time ranges, and reflected in the time‐averaged nuclide production rates. Production rates predicted by the geomagnetic field models are in good agreement with actual measurements from ice cores and sediment records. These global, long‐term production rates are important for a wide range of studies that employ cosmogenic nuclides as a proxy/tracer of different Earth system processes.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We estimated the atmospheric production rates of cosmogenic radionuclides using global geomagnetic field models covering the past 100 ka〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The results show the importance of the multipolar components of the field during the Laschamps excursion〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The variations in production rates predicted by the models agree well with the actual measurements from ice cores〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Academy of Finland http://dx.doi.org/10.13039/501100002341
    Description: University of Oulu
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: Helmholtz‐Zentrum Potsdam ‐ Deutsches GeoForschungsZentrum GFZ http://dx.doi.org/10.13039/501100010956
    Description: https://earthref.org/ERDA/2543/
    Description: https://earthref.org/ERDA/2498/
    Description: https://earthref.org/ERDA/2521/
    Keywords: ddc:538.7 ; cosmogenic isotopes ; production rates ; geomagnetic field ; geomagnetic excursions ; Laschamps event
    Language: English
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    Detection of Copper by the ChemCam Instrument Along Curiosity's Traverse in Gale Crater, Mars: Elevated Abundances in Glen Torridon (2023)
    Details
    Publication Date: 2023-12-14
    Description: Laser‐induced breakdown spectroscopy, as utilized by the ChemCam instrument onboard the Curiosity rover, detected enhanced abundances of the element copper. Since landing in Gale crater (6 August 2012), 10 enhancements in copper abundance were observed during 3007 Martian days (sols) of rover operations and 24 km of driving (as of 20 January 2021). The most prominent ones were found in the Kimberley area on the crater floor (Aeolis Palus) and in Glen Torridon (GT) on the lower flanks of Aeolis Mons (Mt. Sharp). Enhancements in copper record the former existence of modestly acidic and oxidizing fluids, which were more oxidizing in Kimberley than in GT. Of the two main types of bedrock in the lowest part of GT, Mg‐rich “coherent” and K‐rich “rubbly” (named based on their outcrop expression), copper was detected only in coherent, not in rubbly bedrock. The difference between these two types of bedrock may be due to difference in provenance. Alternatively, based on a recently developed lacustrine‐groundwater mixing model, we suggest that rubbly bedrock was altered by modestly acidic, shallow‐subsurface lake water that leached out both copper and manganese, while coherent bedrock was affected by dominantly alkaline fluids which would be consistent with its mineralogical composition (including siderite) as returned by the CheMin instrument onboard the rover. Higher up in GT, ChemCam data indicated significant gradients in the copper concentration in coherent bedrock on a local scale of only a few meters, which suggests a different alteration style and possibly different types of diagenetic fluids.
    Description: Plain Language Summary: Gale crater, Mars, about 152‐km in diameter and 3.6 Ga in age, has a central mound that is partly of sedimentary origin. To date (July 2022), the NASA rover Curiosity has been exploring the crater floor and the lower‐most 600 m (in elevation) of sediments of that mound. ChemCam, an instrument mounted on top of the remote‐sensing mast utilizing Laser‐Induced Breakdown Spectroscopy, has been measuring chemical composition and specifically copper abundances along the rover traverse. We identified 10 areas of copper enhancement along Curiosity's traverse. In the Kimberley formation on the crater floor, copper was identified in a manganese‐rich sandstone. Later on, some 350 m above Kimberley, high copper abundances were detected in magnesium‐rich mudstone and in iron‐rich sandstone in the Jura and Knockfarril Hill member, respectively. Following earlier work about copper in Gale crater (Payré et al., 2019, https://doi.org/10.1016/j.icarus.2018.12.015), we postulate a copper‐rich source region north of Gale crater and suggest that copper‐rich detrital material delivered to these areas in Gale crater. Taking into account the chemical and mineralogical composition of these types of bedrock, we conclude that copper was mobilized by later acidic and oxidizing fluids.
    Description: Key Points: High copper abundances (200–400 ppm) are found in specific areas along the rover traverse. In the Jura member in Glen Torridon (GT), copper is detected only in coherent bedrock, not in rubbly bedrock. In the Knockfarril Hill member in GT, there is evidence for the redistribution of copper and iron by acidic, oxidizing fluids.
    Description: DFG
    Description: NASA Mars Exploration Program
    Description: CNES
    Description: CNRS
    Keywords: ddc:523 ; Mars ; copper ; diagenesis ; Gale crater ; ChemCam ; Curiosity rover
    Language: English
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    A Comparison Study of Mg/Ca‐, Alkenone‐, and TEX86‐Derived Temperatures for the Brazilian Margin (2023)
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The reconstruction of accurate sea‐surface temperatures (SST) is of utmost importance due to the ocean's central role in the global climate system. Yet, a number of environmental processes might bias reliable SST estimations. Here, we investigate the fidelity of SST reconstructions for the western tropical South Atlantic (WTSA) for the interval covered by Marine Isotope Stages (MIS) 6–5, utilizing a core collected off eastern Brazil at ∼20°S. This interval was selected as previous SST estimates based on Mg/Ca ratios of planktic foraminifera suggested a peculiar pooling of warm surface waters in the WTSA during MIS 6 despite glacial boundary conditions. To ground‐truth the Mg/Ca‐based SST data we generated SST reconstructions on the same core material using the alkenone and TEX〈sub〉86〈/sub〉 paleothermometers. Comparison with alkenone‐based temperature estimates corroborate the previous Mg/Ca‐based SST reconstructions, supporting the suggestion of a warm‐water anomaly during MIS 6. In contrast, TEX〈sub〉86〈/sub〉‐derived temperatures, albeit representing annual mean SST in recent core top samples, are up to 6°C colder than Mg/Ca‐ and alkenone‐based SST reconstructions. We interpret the periods of anomalously cold TEX〈sub〉86〈/sub〉‐temperatures as a result of a vertical migration of the TEX〈sub〉86〈/sub〉 producers (heterotrophic marine Thaumarchaeota) toward greater water depths, following food availability during phases of enhanced fluvial suspension input. Likewise, the data suggest that alkenone‐based SST are, albeit to a minor degree when compared to TEX〈sub〉86〈/sub〉, affected by river run‐off and/or a seasonal bias in the growth season of haptophyte algae.〈/p〉
    Description: Plain Language Summary: In this study, we investigate the accuracy of sea‐surface temperature (SST) reconstructions for the western tropical South Atlantic (WTSA) for the interval covered by Marine Isotope Stages (MIS) 6–5—the penultimate glacial‐interglacial cycle (ca. 190,000 to 70,00 years before present). This time interval was selected because previous SST estimates based on Mg/Ca ratios of planktic foraminifera suggested a pooling of warm surface waters in the WTSA during late MIS 6 despite the cold glacial conditions. To verify the Mg/Ca‐based SST data, we generated temperature reconstructions from a core located off Eastern Brazil using two common paleothermometers that based on lipid biomarkers: alkenone and TEX〈sub〉86〈/sub〉. The alkenone‐based temperature estimates agree with previous Mg/Ca‐based SST reconstructions, supporting the existence of a warm‐water anomaly in the WTSA during MIS 6. On the other hand, TEX〈sub〉86〈/sub〉‐derived temperatures were up to 6°C colder than Mg/Ca‐ and alkenone‐based SST reconstructions. This discrepancy might be a result of a vertical migration of the TEX86 producers toward greater water depths where they feed on particles of organic matter. These migrations into deeper waters occurred during phases of increased river run‐off fluvial suspension input which enhanced surface primary productivity and facilitated vertical particle flux through the water column.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Parallel Mg/Ca (〈italic〉Globigerinoides ruber〈/italic〉), alkenone and TEX〈sub〉86〈/sub〉‐based temperature estimates in the western tropical South Atlantic (WTSA) across Marine Isotope Stages (MIS) 6–5〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Mg/Ca and alkenones represent annual mean sea surface temperatures, but most TEX〈sub〉86〈/sub〉‐based temperatures deviate to colder values〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Anomalous sea surface warming in the WTSA during late MIS 6 appears as a robust signal〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: R/V METEOR
    Description: DFG
    Description: CNPq
    Description: FAPESP
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: https://doi.org/10.1594/PANGAEA.956207
    Keywords: ddc:551 ; Mg/Ca ; alkenones ; TEX86 ; MIS 6 ; Brazilian Margin ; MIS 5
    Language: English
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    Mapping the 3D position of battery cathode particles in Bragg coherent diffractive imaging (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-12-14
    Description: In Bragg coherent diffractive imaging, the precise location of the measured crystals in the interior of the sample is usually missing. Obtaining this information would help the study of the spatially dependent behavior of particles in the bulk of inhomogeneous samples, such as extra‐thick battery cathodes. This work presents an approach to determine the 3D position of particles by precisely aligning them at the instrument axis of rotation. In the test experiment reported here, with a 60 µm‐thick LiNi0.5Mn1.5O4 battery cathode, the particles were located with a precision of 20 µm in the out‐of‐plane direction, and the in‐plane coordinates were determined with a precision of 1 µm.
    Description: A method to determine the 3D position of particles in Bragg coherent diffractive imaging experiments is proposed. Test measurements demonstrate depth‐resolution with a precision of 20 µm along the beam. image
    Keywords: ddc:548 ; extra‐thick battery cathodes ; Bragg coherent X‐ray diffractive imaging ; battery cathodes ; Bragg diffraction ; sphere of confusion ; 3D mapping
    Language: English
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    A staging system for Atlantic herring (Clupea harengus) larvae based on external morphology and skeletal development (2023)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Atlantic herring (〈italic toggle="no"〉Clupea harengus〈/italic〉) plays a key role within temperate marine food webs and is targeted by a significant over‐regional fishery. Due to its high economic importance, dynamics in herring stock biomass and recruitment are closely monitored, forming the basis for fisheries management advice. As recruitment patterns translate into the adult stock biomass, early life stage ecology has been thoroughly addressed in fisheries research. Larval monitoring programs commonly focus on length measurements and abundance indices, rarely, information on larval developmental stages is given. As length is highly influenced by temperature, salinity and food availability, their size range can significantly vary between cohorts, populations, and ecotypes. Nowadays, a systematic staging system from the 1970s provides the standard guide for herring larval development, although it does not fully resolve important developmental stages. Here, we propose an improved staging system based on external morphology and skeletal development of herring larvae. The staging system has been developed and tested with herring larvae from different populations of the North and Baltic Sea to ensure applicability. The system comprises 15 stages (+substages) in 5 major developmental phases: the yolk sac phase, the dorsal fin development, the caudal fin development, the pelvic fin development, and the juvenile phase. This staging system aims to simplify herring larval staging to gain a more specific picture of early life dynamics. Because of the detailed description of the development, future studies are better equipped to identify stages which, for example, show high mortality rates and better link them to environmental circumstances.〈/p〉
    Description: Universität Rostock http://dx.doi.org/10.13039/501100012688
    Description: Promotionsstipendium Universität Rostock
    Keywords: ddc:597 ; Atlantic herring ; larval phases ; staging system
    Language: English
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    Domestic water versus imported virtual blue water for agricultural production: A comparison based on energy consumption and related greenhouse gas emissions (2023)
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The supply of water, food, and energy in our global economy is highly interlinked. Virtual blue water embedded into internationally traded food crops has therefore been extensively researched in recent years. This study focuses on the often neglected energy needed to supply this blue irrigation water. It provides a globally applicable and spatially explicit approach to the watershed level for water source specific quantification of energy consumption and related greenhouse gas (GHG) emissions of irrigation water supply. The approach is applied to Israel's total domestic and imported food crop supply of 105 crops by additionally including import‐related transportation energy and emissions. Total energy use and related emissions of domestic crop production were much lower (551 GWh/422 kt CO〈sub〉2〈/sub〉‐equivalents [CO〈sub〉2〈/sub〉e]) than those embedded into crop imports (1639 GWh/649 kt CO〈sub〉2〈/sub〉e). Domestic energy and emissions were mainly attributable to the irrigation water supply with artificial water sources (treated domestic wastewater and desalinated water, 84%). Transport accounted for 79% and 66% of virtually imported energy and emissions, respectively. Despite transport, specific GHG emissions (CO〈sub〉2〈/sub〉e per ton of crop) were significantly lower for several crops (e.g., olives, almonds, chickpeas) compared to domestic production. This could be attributed to the high share of energy‐intensive artificial water supply in combination with higher irrigation water demands in Israel. In the course of an increasing demand for artificial water supply in arid and semi‐arid regions, our findings point to the importance of including “energy for water” into comparative environmental assessment of crop supply to support decision‐making related to the water–energy–food nexus.〈/p〉
    Description: MedWater
    Description: Federal Ministry of Education and Research, Germany
    Keywords: ddc:553.7 ; agricultural water use ; energy for water ; industrial ecology ; Israel ; virtual water flows ; greenhouse gas emissions
    Language: English
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    Parasites and Pollutants: Effects of Multiple Stressors on Aquatic Organisms (2023)
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Parasites can affect their hosts in various ways, and this implies that parasites may act as additional biotic stressors in a multiple‐stressor scenario, resembling conditions often found in the field if, for example, pollutants and parasites occur simultaneously. Therefore, parasites represent important modulators of host reactions in ecotoxicological studies when measuring the response of organisms to stressors such as pollutants. In the present study, we introduce the most important groups of parasites occurring in organisms commonly used in ecotoxicological studies ranging from laboratory to field investigations. After briefly explaining their life cycles, we focus on parasite stages affecting selected ecotoxicologically relevant target species belonging to crustaceans, molluscs, and fish. We included ecotoxicological studies that consider the combination of effects of parasites and pollutants on the respective model organism with respect to aquatic host–parasite systems. We show that parasites from different taxonomic groups (e.g., Microsporidia, Monogenea, Trematoda, Cestoda, Acanthocephala, and Nematoda) clearly modulate the response to stressors in their hosts. The combined effects of environmental stressors and parasites can range from additive, antagonistic to synergistic. Our study points to potential drawbacks of ecotoxicological tests if parasite infections of test organisms, especially from the field, remain undetected and unaddressed. If these parasites are not detected and quantified, their physiological effects on the host cannot be separated from the ecotoxicological effects. This may render this type of ecotoxicological test erroneous. In laboratory tests, for example to determine effect or lethal concentrations, the presence of a parasite can also have a direct effect on the concentrations to be determined and thus on the subsequently determined security levels, such as predicted no‐effect concentrations. 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:577.6 ; Aquatic toxicology ; Contaminants ; Ecotoxicology ; Environmental toxicology ; Stressor
    Language: English
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    FID GEO latest: How to cite data publications correctly (2023)
    Details
    Publication Date: 2023-12-07
    Description: Publishing data with a DOI (Digital Object Identifier) is becoming increasingly popular, and many researchers are being asked by journals to publish the data underlying the research results described in the article. Where does the data come from and how do I cite it correctly? […] This publication is a translation of the FID GEO article in 〈a href="http://doi.org/10.23689/fidgeo-5688"〉GMIT 90.〈/a〉
    Description: research
    Keywords: ddc:550 ; GMIT ; Geowissenschaftliche Mitteilungen
    Language: English
    Type: doc-type:article , publishedVersion
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    FID GEO latest: Recommendations for using ORCID iD (2023)
    Details
    Publication Date: 2023-12-07
    Description: The ORCID is an open alphanumeric identifier used to uniquely identify researchers.In an increasingly connected scientific landscape, the growing number of published research outputs (data, text, software) and new open publishing models pose major challenges for scientific publication management. The repositories available to FID GEO, GEO-LEOe-docs (SUB Goettingen) and GFZ Data Services (GFZ), have long been working with PIDs such as the Digital Object Identifier (DOI ) and the Open Researcher and Contributor iD (ORCID iD ), and recommend the use of the ORCID. This publication is a translation of the FID GEO article in 〈a href="http://doi.org/10.23689/fidgeo-5832"〉GMIT 87.〈/a〉
    Description: DFG, SUB Göttingen, GFZ Potsdam
    Description: research
    Keywords: ddc:550 ; GMIT
    Language: English
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    The Role of Mineral Dust Aerosol Particles in Aviation Soot‐Cirrus Interactions (2023)
    Details
    Publication Date: 2023-12-19
    Description: Predicting cirrus cloud properties with confidence requires a sound understanding of the relative roles of homogeneous and heterogeneous ice formation. This study explores the effect of mineral dust and contrail‐processed aviation soot particles as ice‐nucleating particles (INPs) competing with liquid solution droplets in cirrus formation. We study aerosol‐cirrus interactions by accounting for atmospheric variability in updraft speeds and INP number concentrations. Our results confirm the dominant role of mineral dust in ice nucleation events in cirrus clouds. In addition, we show that pre‐existing thin cirrus may suppress ice formation when updraft speeds are low. We find that homogeneous freezing of liquid solution droplets dominates clear‐sky aerosol‐cirrus interaction above a threshold updraft speed determined by total number concentrations and ice nucleation abilities of INPs. When mineral dust particles exceed number concentrations of 10 L〈sup〉−1〈/sup〉, they reduce homogeneously nucleated ice crystal numbers significantly and even prevent homogeneous freezing for frequently observed local updraft speeds between 10 and 20 cm s〈sup〉−1〈/sup〉. When both mineral dust and aviation soot particles coexist with solution droplets, dust typically prevents ice nucleation by aviation soot. Aviation soot exerts a notable impact on cirrus ice numbers only if updrafts are weak, large soot particles are present in number concentrations that are considerably higher than typically observed in emission measurements, and/or number concentrations of mineral dust and other INPs are low. Overall, our results elucidate the role of aviation soot‐cirrus interactions in the presence of other INP types.
    Description: Plain Language Summary: Understanding ice formation from atmospheric aerosol particles in cirrus clouds is important to correctly predict the impact of cirrus on climate. Here, we study for the first time on the process level cirrus ice formation from freezing of liquid solution droplets in competition with ice nucleation on mineral dust and aviation‐produced soot particles. Our results show that in the majority of cloud‐forming updrafts, mineral dust particles dominate cirrus formation over droplet freezing and that they outcompete aviation soot in producing cloud ice. Moreover, already existing cirrus clouds often prevent ice formation from these particle types altogether. Our results help evaluate cirrus parameterizations within global models and constrain model‐based estimates of the global climate impact of aviation.
    Description: Key Points: Mineral dust outcompetes contrail‐processed aviation soot in aerosol‐cirrus interactions. Mineral dust reduces homogeneously nucleated ice crystal numbers more effectively than aviation soot. Strong potential of pre‐existing cirrus clouds to suppress new cloud ice formation.
    Description: European Commission http://dx.doi.org/10.13039/501100000780
    Description: https://doi.org/10.5281/zenodo.7404707
    Keywords: ddc:551.5 ; ice nucleating particles ; cirrus ; aerosol cloud interactions
    Language: English
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    Mid‐Infrared Spectroscopy of Feldspars From the Bühl Basalt (Northern Hesse, Germany) Formed Under Reducing Conditions as Terrestrial Analogue of Mercury for MERTIS (2023)
    Details
    Publication Date: 2023-12-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The MErcury Radiometer and Thermal Infrared Spectrometer instrument onboard the BepiColombo spacecraft is designed to investigate Mercury’s surface in the mid‐infrared (mid‐IR). Based on MESSENGER data and modeling, Mercury is thought to be evolved under highly reducing conditions (e.g., McCubbin et al., 2017, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/2017JE005367"〉https://doi.org/10.1002/2017JE005367〈/ext-link〉; Namur & Charlier, 2017, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1038/ngeo2860"〉https://doi.org/10.1038/ngeo2860〈/ext-link〉). The modeling also indicates that Mercury's surface is rich in feldspar. However, it is unknown if reducing conditions during the emplacement of volcanic melts have an influence on the IR properties of feldspars. Therefore, we investigated basaltic samples from the Bühl quarry in northern Hesse, Germany, that evolved under reducing conditions in the mid‐IR and compared the spectra with samples that experienced more oxidizing conditions during their formation. The Bühl samples are feldspar‐rich and contain metallic iron in some areas. Our investigations show that there are no differences between feldspars that formed under different oxidizing conditions. All spectral properties could be explained by well‐known factors that affect mid‐IR spectra of silicates.〈/p〉
    Description: Plain Language Summary: ESA's and Japan Aerospace Exploration Agency’s spacecraft BepiColombo is equipped, beside other instruments, with a thermal infrared (IR) radiometer and spectrometer called MErcury Radiometer and Thermal Infrared Spectrometer (MERTIS). For the accurate interpretation of the data from the MERTIS instrument, laboratory analog material is necessary. This analog material must fulfill different characteristics, such as different chemical and mineralogical compositions. Another not yet studied property is the availability of oxygen during the formation of the minerals. Depending on how much oxygen is available, different minerals form. However, this is an important feature, because Mercury is thought to have evolved under highly reducing conditions, as opposed to Earth where nearly all material formed significant more oxidizing conditions. One phase that is strongly associated with reducing magma formation conditions is metallic iron. There are only few natural outcrops on Earth, were stronger reducing conditions were present so that metallic iron could be formed. One of these outcrops is the Bühl quarry in northern Hesse, Germany. From there we used different samples to analyze the effect of oxygen availability on mid‐IR spectra of plagioclase feldspars.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We present infrared spectra of basaltic samples from the Bühl, Hesse, Germany in preparation of the MERTIS experiment〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Comparison of feldspars formed at different oxygen fugacities showed no spectral differences〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉This is an important result for MERTIS, which will investigate Mercury that formed under reducing conditions〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: DLR
    Description: http://bc-mertis-pi.uni-muenster.de/
    Keywords: ddc:549 ; infrared reflectance spectroscopy ; feldspars ; Bühl basalt ; reducing conditions ; Mercury ; MERTIS
    Language: English
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    Assessing Precipitation Over the Amazon Basin as Simulated by a Storm‐Resolving Model (2023)
    Details
    Publication Date: 2023-12-19
    Description: In this study, we investigate whether a better representation of precipitation in the Amazon basin arises through an explicit representation of convection and whether it is related to the representation of organized systems. In addition to satellite data, we use ensemble simulations of the ICON‐NWP model at storm‐resolving (2.5–5.0 km) scales with explicit convection (E‐CON) and coarse resolutions, with parameterized convection (P‐CON). The main improvements in the representation of Amazon precipitation by E‐CON are in the distribution of precipitation intensity and the spatial distribution in the diurnal cycle. By isolating precipitation from organized convective systems (OCS), it is shown that many of the well simulated precipitation features in the Amazon arise from the distribution of these systems. The simulated and observed OCS are classified into 6 clusters which distinguish nocturnal and diurnal OCS. While the E‐CON ensembles capture the OCS, especially their diurnal cycle, their frequency is reduced compared to observations. Diurnal clusters are influenced by surface processes such as cold pools, which aid to the propagation of OCS. Nocturnal clusters are rather associated with strong low‐level easterlies, possibly related to the Amazonian low‐level jet. Our results also show no systematic improvement with a twofold grid refinement and remaining biases related to stratiform features of OCS suggest that yet unresolved processes play an important role for correctly representing precipitating systems in the Amazon.
    Description: Plain Language Summary: The Amazon basin is a relevant element of the Earth system because it influences the global water and carbon cycle, as well as it constitutes a unique ecosystem. Over this important region, conventional climate models do not simulate basic features of rainfall given their inability to resolve this physical process due to their coarse spatial resolution. In this study, we use high‐resolution simulations that allow an explicit representation of such physical process (moist convection) and compare them with a set of coarse‐resolution simulations and observed precipitation. We find that improvements in the representation of Amazon rainfall, such as the distribution of light and high intensity rain rates, as well as the spatial variability of the diurnal cycle, are explained by the explicit representation of moist convection. Moreover, these improvements arise from the representation of big and organized systems that produce intense rainfall (OCS). We find that particular environmental conditions are associated with the OCS according to their time of occurrence. Diurnal OCS are mainly influenced by interactions with the surface, while nocturnal OCS are related to strong low‐level winds. Some of the remaining discrepancies with observed OCS do not show improvements when refining the grid by a factor of two.
    Description: Key Points: An explicit representation of convection enables the emergence of organized systems (OCS) leading to improved simulations of Amazon rainfall. Propagating cold‐pools and strong low‐level easterlies are related to the occurrence of diurnal and nocturnal OCS, respectively. Systematic biases in the size, intensity and nocturnal precipitation phase of OCS are insensitive to a twofold refinement in resolution.
    Description: Max Planck Society for the Advancement of Science
    Description: European Horizon 2020 project CONSTRAIN
    Description: https://www.metoffice.gov.uk/hadobs/hadisst/data/download.html
    Description: https://www.ncei.noaa.gov/data/cmorph-high-resolution-global-precipitation-estimates/access/30min/8km
    Description: https://www.hydrosheds.org/products/hydrobasins
    Description: https://esgf-data.dkrz.de/projects/cmip6-dkrz/
    Description: https://pure.mpg.de/
    Keywords: ddc:551.6 ; Amazon rainfall ; organized precipitating systems ; storm‐resolving simulation
    Language: English
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    High‐resolution in situ stable isotope measurements reveal contrasting atmospheric vapour dynamics above different urban vegetation (2023)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-19
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉We monitored stable water isotopes in liquid precipitation and atmospheric water vapour (δ〈sub〉v〈/sub〉) using in situ cavity ring‐down spectroscopy (CRDS) over a 2 month period in an urban green space area in Berlin, Germany. Our aim was to better understand the origins of atmospheric moisture and its link to water partitioning under contrasting urban vegetation. δ〈sub〉v〈/sub〉 was monitored at multiple heights (0.15, 2 and 10 m) in grassland and forest plots. The isotopic composition of δ〈sub〉v〈/sub〉 above both land uses was highly dynamic and positively correlated with that of rainfall indicating the changing sources of atmospheric moisture. Further, the isotopic composition of δ〈sub〉v〈/sub〉 was similar across most heights of the 10 m profiles and between the two plots indicating high aerodynamic mixing. Only at the surface at ~0.15 m height above the grassland δ〈sub〉v〈/sub〉 showed significant differences, with more enrichment in heavy isotopes indicative of evaporative fractionation especially after rainfall events. Further, disequilibrium between δ〈sub〉v〈/sub〉 and precipitation composition was evident during and right after rainfall events with more positive values (i.e., values of vapour higher than precipitation) in summer and negative values in winter, which probably results from higher evapotranspiration and more convective precipitation events in summer. Our work showed that it is technically feasible to produce continuous, longer‐term data on δ〈sub〉v〈/sub〉 isotope composition in urban areas from in situ monitoring using CRDS, providing new insights into water cycling and partitioning across the critical zone of an urban green space in Central Europe. Such data have the potential to better constrain the isotopic interface between the atmosphere and the land surface and to thus, improve ecohydrological models that can resolve evapotranspiration fluxes.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉In situ measurements of urban atmospheric water isotopes (δ〈sub〉v〈/sub〉) at different heights produce reliable and stable high‐resolution data. Urban atmospheric vapour is influenced by varying drivers depending on the type of green space. δ〈sub〉v〈/sub〉 above grassland and tree stands was similar at 10 m height, but near‐surface δ〈sub〉v〈/sub〉 indicated higher evaporation and vapour enrichment over grass. We detected occasional dis‐equilibrium between vapour and precipitation isotopes.〈boxed-text position="anchor" content-type="graphic" id="hyp14989-blkfxd-0001" xml:lang="en"〉 〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:08856087:media:hyp14989:hyp14989-toc-0001"〉 〈/graphic〉 〈/boxed-text〉〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: German Research Foundation http://dx.doi.org/10.13039/501100001659
    Description: Einstein Research Unit
    Description: Einstein Foundation Berlin and Berlin University Alliance
    Description: BiNatur
    Description: BMBF http://dx.doi.org/10.13039/501100002347
    Description: Leverhulme Trust through the ISO‐LAND project
    Keywords: ddc:551.6 ; atmospheric vapour isotopes ; cities ; ecohydrology ; equilibrium assumption ; in situ monitoring ; urban green spaces
    Language: English
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    The soft X‐ray and XUV split‐and‐delay unit at beamlines FL23/24 at FLASH2 (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2024-01-12
    Description: A split‐and‐delay unit for the extreme ultraviolet and soft X‐ray spectral regions has been built which enables time‐resolved experiments at beamlines FL23 and FL24 at the Free‐electron LASer in Hamburg (FLASH). Geometric wavefront splitting at a sharp edge of a beam splitting mirror is applied to split the incoming soft X‐ray pulse into two beams. Ni and Pt coatings at grazing incidence angles have been chosen in order to cover the whole spectral range of FLASH2 and beyond, up to hν = 1800 eV. In the variable beam path with a grazing incidence angle of ϑd = 1.8°, the total transmission (T) ranges are of the order of 0.48 〈 T 〈 0.84 for hν 〈 100 eV and T 〉 0.50 for 100 eV 〈 hν 〈 650 eV with the Ni coating, and T 〉 0.06 for hν 〈 1800 eV for the Pt coating. For a fixed beam path with a grazing incidence angle of ϑf = 1.3°, a transmission of T 〉 0.61 with the Ni coating and T 〉 0.23 with a Pt coating is achieved. Soft X‐ray pump/soft X‐ray probe experiments are possible within a delay range of −5 ps 〈 Δt 〈 +18 ps with a nominal time resolution of tr = 66 as and a measured timing jitter of tj = 121 ± 2 as. First experiments with the split‐and‐delay unit determined the averaged coherence time of FLASH2 to be τc = 1.75 fs at λ = 8 nm, measured at a purposely reduced coherence of the free‐electron laser.
    Description: The properties of the recently installed split‐and‐delay unit at beamlines FL23 and FL24 at FLASH2 are presented. Its operational range, performance parameters and results of a first experiment are described. image
    Keywords: ddc:550.724 ; time‐resolved pump–probe ; XUV ; soft X‐rays ; free‐electron laser
    Language: English
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  • 80
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    A Depth‐Averaged Description of Submarine Avalanche Flows and Induced Surface Waves (2023)
    Details
    Publication Date: 2024-01-12
    Description: This paper develops a depth‐averaged theory to investigate submarine landslides and resulting water waves. The problems here consist of a pure fluid regime and a mixture regime of grains and fluid. Both regimes separate from one another by an interface, which is a material surface for grains. While the downslope velocities of the both phases are assumed to be identical in the mixture regime, the velocity shear causes a rearrangement of grains, which induces a vertical relative motion between the phases. The established theory consists of five coupled conservation equations, which describe the evolution of the pure fluid thickness, the mixture thickness, the solids volume fraction, and depth‐averaged velocities. To handle nonconservative products emerging in the equations, a new coordinate system is introduced to rewrite the equation system in an equivalent form, so that numerical solutions are insensitive to the choice of discretization of nonconservative products, which enables us to accurately characterize the dynamic behaviors of particles in the collapse experiments of underwater particles and describe free‐surface wave profiles. It is shown that the computed results are in good agreement with the experiments reported in previous literatures.
    Description: Plain Language Summary: Developing an accurate and rigorous model to describe the motion of submarine landslides and the evolution of the induced water wave remains a challenge to date. Existing models usually simplify the submarine mass as a sling box or a deformable rheological material which is unable to interpret certain fast‐moving and some slow‐moving granular flows that differ only in their compactness. In this paper, the existing models are improved by taking account of the dilatancy effects of the particles. Numerical results of underwater granular collapse show that the predictions of the temporal evolution of the thickness profiles and the final deposit morphology using the current model are in better agreement with experiments compared to the existing models. The present model also provides a better prediction in the wave profiles induced by submarine landslides, which makes the present theory very promising to investigate natural geophysical flows in the future.
    Description: Key Points: A depth‐averaged model is presented, which considers excess pore fluid pressure and fluid mass transfer across the avalanche surface. A robust numerical method is used, so that the computed solution is insensitive to the way nonconservative products are discretized. Significant improvements in the prediction of the grain thickness profiles and the free‐surface waves are found compared with existing models.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Fundamental Research Funds for the Central Universities http://dx.doi.org/10.13039/501100012226
    Description: National Key Research and Development Program of China http://dx.doi.org/10.13039/501100012166
    Description: https://doi.org/10.48328/tudatalib-931
    Keywords: ddc:551.3 ; submarine landslides ; granular dilatancy ; depth‐averaged theory ; nonoscillatory central‐upwind scheme ; free surface wave flow
    Language: English
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  • 81
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    DeepLandforms: A Deep Learning Computer Vision Toolset Applied to a Prime Use Case for Mapping Planetary Skylights (2023)
    Details
    Publication Date: 2024-01-12
    Description: Thematic map creation is a meticulous process that requires several steps to be accomplished regardless of the type of map to be produced, from data collection, through data exploitation and map publication in print, image, and GIS format. Examples are geolithological, and geomorphological maps in which most of the highest time‐consuming tasks are those related to the discretization of single objects. Introducing also interpretative biases because of the different experience of the mappers in identifying a set of unique characteristics that describe those objects. In this setting, Deep Learning Computer Vision techniques could play a key role but lack the availability of a complete set of tools specific for planetary mapping. The aim of this work is to develop a comprehensive set of ready‐to‐use tools for landforms mapping based on validated Deep Learning methodologies and open‐source libraries. We present DeepLandforms, the first pre‐release of a toolset for landform mapping using Deep Learning that includes all the components for data set preparation, model training, monitoring, and inference. In DeepLandforms, users have full access to the workflow and control over all the processes involved, granting complete control and customization capabilities. In order to validate the applicability of our tool, in this work we present the results achieved using DeepLandforms in the science case of mapping sinkhole‐like landforms on Mars, as a first example that can lead us into multiple and diverse future applications.
    Description: Plain Language Summary: The creation of maps is a complex set of several tasks that, regardless of the type of map, are often very time‐consuming. For instance, all the occurrences of a specific object, natural or man‐made in a defined area, need to be identified, drawn and classified manually. Mapping large objects in small areas is an easy task but may be unmanageable in cases such as small landforms on the entire surface of a planet. Nowadays, especially on Earth, researchers and professionals take advantages of highly specialized software based on a technique called Deep Learning. Such software are almost never free nor ready‐to‐use and often requires higher knowledge in computer programming languages. In this work, we present the first pre‐release of a novel open‐source computer software, nearly ready‐to‐use, that provides all the instruments for approaching Deep Learning for automatic landforms mapping. We present also the results obtained by trying this software using data of Mars's surface to map sinkhole‐like landforms.
    Description: Key Points: Instance Segmentation methodology is used to map landforms obtaining vectorial data in geopackage file format. A newly developed composite toolset to perform image pre‐processing, data labeling, model training and inference tasks is presented. The results of a prime case of mapping pit and skylights on Mars surface are showed.
    Description: European Union's Horizon 2020 research and innovation programme
    Description: https://doi.org/10.5281/zenodo.7351391
    Description: https://doi.org/10.5281/zenodo.7488867
    Description: https://ode.rsl.wustl.edu/odeholdings/Mars_holdings.html
    Keywords: ddc:523 ; mapping ; Mars ; pits ; skylight ; deep learning ; toolset
    Language: English
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    XDSGUI: a graphical user interface for XDS, SHELX and ARCIMBOLDO (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2024-01-12
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉〈italic〉XDSGUI〈/italic〉 is a lightweight graphical user interface (GUI) for the 〈italic〉XDS〈/italic〉, 〈italic〉SHELX〈/italic〉 and 〈italic〉ARCIMBOLDO〈/italic〉 program packages that serves both novice and experienced users in obtaining optimal processing and phasing results for X‐ray, neutron and electron diffraction data. The design of the program enables data processing and phasing without command line usage, and supports advanced command flows in a simple user‐modifiable and user‐extensible way. The GUI supplies graphical information based on the tabular log output of the programs, which is more intuitive, comprehensible and efficient than text output can be.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉A customizable stateless graphical user interface simplifies the processing, analysis and phasing of diffraction data.〈boxed-text position="anchor" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:16005767:jcr2yr5110:jcr2yr5110-fig-0001"〉 〈alt-text〉image〈/alt-text〉 〈/graphic〉〈/boxed-text〉〈/p〉
    Keywords: ddc:548 ; X‐ray diffraction ; neutron diffraction ; electron diffraction ; data processing ; graphical user interfaces ; phasing ; XDS ; ARCIMBOLDO ; SHELX
    Language: English
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    An ambitious new mission seeks the origin of the moons of Mars (2023)
    Details
    Publication Date: 2023-03-21
    Description: Two mysterious moons whirl around Mars. Despite the many missions to the planet, not a single one has focused on its satellites — or, rather, not a single successful one. Three previous Martian moon explorers, launched by Russia or the Soviet Union, all failed. Now Japan is trying its luck with a high-risk venture that aims to grab rocks from the larger Martian moon and bring them to Earth for laboratory analysis. “It’s a very scary mission,” says Tomohiro Usui of the Japan Aerospace Exploration Agency (JAXA) in Sagamihara. The spacecraft’s daunting tasks will include multiple touchdowns on a heavily cratered world. The chief goal is to settle a debate over the origin of the moons (1). Did the Red Planet steal them from the asteroid belt, or did they form after an asteroid smashed into Mars? The answer carries implications for satellites elsewhere and perhaps even for the origin of water on Earth.
    Description: report
    Keywords: ddc:520 ; Mars ; Monde ; moons
    Language: English
    Type: doc-type:article , publishedVersion
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  • 84
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    Dissolved gases in the deep North Atlantic track ocean ventilation processes (2023)
    Details
    Publication Date: 2023-03-21
    Description: Gas exchange between the atmosphere and ocean interior profoundly impacts global climate and biogeochemistry. However, our understanding of the relevant physical processes remains limited by a scarcity of direct observations. Dissolved noble gases in the deep ocean are powerful tracers of physical air-sea interaction due to their chemical and biological inertness, yet their isotope ratios have remained underexplored. Here, we present high-precision noble gas isotope and elemental ratios from the deep North Atlantic (~32°N, 64°W) to evaluate gas exchange parameterizations using an ocean circulation model. The unprecedented precision of these data reveal deep-ocean undersaturation of heavy noble gases and isotopes resulting from cooling-driven air-to-sea gas transport associated with deep convection in the northern high lati-tudes. Our data also imply an underappreciated and large role for bubble-mediated gas exchange in the global air-sea transfer of sparingly soluble gases, including O2, N2, and SF6. Using noble gases to validate the physical representation of air-sea gas exchange in a model also provides a unique opportunity to distinguish physical from biogeochemical signals. As a case study, we compare dissolved N2/Ar measurements in the deep North Atlantic to physics-only model predictions, revealing excess N2 from benthic denitrification in older deep waters (below 2.9 km). These data indicate that the rate of fixed N removal in the deep Northeastern Atlantic is at least three times higher than the global deep-ocean mean, suggesting tight coupling with organic carbon export and raising potential future implications for the marine N cycle.
    Description: NSF, UK NERC, University of Oxford Advanced Research Computing facility
    Description: https://www.bco-dmo.org/project/887496
    Description: research
    Keywords: ddc:551 ; gas exchange ; nitrogen cycle ; overturning circulation ; air-sea interaction ; noble gases
    Language: English
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  • 85
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    Application of Phase-Based Edge Detectors to Magnetic Data for Explosive Ordnance Detection (2023)
    Details
    Publication Date: 2023-03-20
    Description: Geophysical sensing methods such as magnetics, electromagnetics and ground penetrating radar are the essential methods for the detection of unexploded ordnances (UXO) in the subsurface. Apart from a precise localization of buried ammunition remnants, a reliable discrimination of anomaly signatures caused by UXO and Non-UXO bodies is one of the currently most challenging tasks in the field of explosive ordnance clearance. Therefore, we exploit different phase-based edge detectors to evaluate their applicability for improving the detection performance and especially for distinguishing buried objects by the anomaly signature they cause. In the present poster, we apply our new approach on synthetic magnetic data for spherical and elliptical object geometries. Furthermore, we compare the synthetic cases to real magnetic survey data collected from a test site at SENSYS GmbH in Bad Saarow.
    Description: poster
    Keywords: edge detection ; UXO ; magnetics
    Language: English
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    Assessing PS-InSAR ground motion data toward stability monitoring of coastal flood protection dikes (2023)
    Details
    Publication Date: 2023-03-15
    Description: Sea level rise caused by climate change represents a challenge to coastal flood protection measures, particularly in regions such as the federal state of Schleswig-Holstein. Large parts along the North Sea coast are protected by dikes and offshore islands provide additional shelter to the hinterland, which often lies just above or even beneath sea level. We have examined InSAR time series data from the German Ground Motion Service along the entire west coast dike route from the Danish border to Wedel. We want to estimate how these data can be used to detect and monitor ground motion processes related to dikes, especially in cases where PS (persistent scatterer) are irregularly distributed. We found, that mainly those parts of the dikes can be monitored by PS interferometry where the seaward dike base is shielded by heavy armourstone acting as sufficient back-scatters for radar waves. Here, ground motion processes induced by additional load of reinforcing construction work can be observed. In some regions the dikes are influenced by long-term, large-scale subsidence. We performed statistical analysis on low pass filtered PS time series to automatically identify significant ground motion and/or ground motion events within a local area of interest. Preliminary results suggest, that we may be able to identify dike segments which show signs of anomalous ground motion and thus should be monitored closely.
    Description: poster
    Keywords: InSAR ; Ground motion ; Schleswig-Holstein ; Dike ; Geophysik
    Language: English
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    The Ice Data Hub as a powerful interface between data and simulations (2023)
    Details
    Publication Date: 2023-03-14
    Description: Providing measurements for scientific simulation software often requires tedious manual preprocessing of data sets. To overcome this problem and make it easy for simulation tools to access heterogeneous data sets directly, we have developed the Ice Data Hub. The Ice Data Hub combines available data from Earth or other planetary bodies including their meta data and allows it to be displayed, interpreted and exported. Most important is its functionality as an interface between data and simulation tools. For example, we develop models for thermodynamic melting processes that can evaluate measured data directly thanks to the Ice Data Hub. It can also be used as a black box, where a simulation tool queries the Hub to provide a property. This could, for example, be a material property at a certain depth. The accessing functionality for the user is wrapped in the sense that the user uses similar routines, regardless the format of data, e.g., analytical expression, look-up table or interpolant. To illustrate the capabilities of the Ice Data Hub, we show results of 1) thermal conductivity simulations in glacial ice with temperature data from Langenferner Glacier, Italy, and 2) trajectory models of ice melting probes compared with housekeeping data from field experiments at Taylor Glacier, Antarctica. 1) The observed temperature evolution from a measured time series of 1D temperature observations in an interval of one hour differs from the theoretically predicted temperature evolution, which was determined on the basis of an idealised seasonal and diurnal temperature variation at the surface and constant ice material parameters. Hence, we reconstruct spatio-temporally varying effective material parameters from these observations using the Crank Nicolson Method. 2) Ice melting probes are developed to penetrate ice and access potential subglacial water reservoirs for insitu studies. The ice-sheet transit provides an excellent opportunity to study the structure and composition of the ice itself using geophysical and other in-situ measurements. Both housekeeping data and scientific sensors of the ice melting probe can be used to derive ice properties and analyse it with various tools via the Ice Data Hub. The Ice Data Hub facilitates the functionality needed to make data repositories of different format simulationready and guarantee reproducibility of data-integrated simulations. It is planned to make the Ice Data Hub available as open source software in the near future.
    Description: poster
    Language: English
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    Deciphering the Whisper of Volcanoes: Monitoring Velocity Changes at Kamchatka's Klyuchevskoy Group With Fluctuating Noise Fields (2023)
    Details
    Publication Date: 2023-06-21
    Description: Volcanic inflation and deflation often precede eruptions and can lead to seismic velocity changes (dv/v $dv/v$) in the subsurface. Recently, interferometry on the coda of ambient noise‐cross‐correlation functions yielded encouraging results in detecting these changes at active volcanoes. Here, we analyze seismic data recorded at the Klyuchevskoy Volcanic Group in Kamchatka, Russia, between summer of 2015 and summer of 2016 to study signals related to volcanic activity. However, ubiquitous volcanic tremors introduce distortions in the noise wavefield that cause artifacts in the dv/v $dv/v$ estimates masking the impact of physical mechanisms. To avoid such instabilities, we propose a new technique called time‐segmented passive image interferometry. In this technique, we employ a hierarchical clustering algorithm to find periods in which the wavefield can be considered stationary. For these periods, we perform separate noise interferometry studies. To further increase the temporal resolution of our results, we use an AI‐driven approach to find stations with similar dv/v $dv/v$ responses and apply a spatial stack. The impacts of snow load and precipitation dominate the resulting dv/v $dv/v$ time series, as we demonstrate with the help of a simple model. In February 2016, we observe an abrupt velocity drop due to the M7.2 Zhupanov earthquake. Shortly after, we register a gradual velocity increase of about 0.3% at Bezymianny Volcano coinciding with surface deformation observed using remote sensing techniques. We suggest that the inflation of a shallow reservoir related to the beginning of Bezymianny's 2016/2017 eruptive cycle could have caused this local velocity increase and a decorrelation of the correlation function coda.
    Description: Plain Language Summary: Before eruptions, volcanoes inflate due to the rising magma from below. Previous studies have found that these deformations can lead to small changes in the properties of the surrounding rock. We use passive image interferometry, a method that relies on the omnipresent background vibration of the Earth—mostly induced by the oceans, to measure these changes at the Klyuchevskoy Volcanic Group in Kamchatka, Russia. However, in Kamchatka, this background noise is masked and distorted by small earthquakes and tremors originating from the volcanoes themselves. We combine machine learning techniques with established monitoring methods to find times when these tremors remain similar. Afterward, we use data from these time periods in the conventional way to observe changes in the soil and the rock. Our results show that rain‐ and snowfall and the thickness of the snow cover exert the strongest influence on the properties of the rocks. Additionally, we found that a large magnitude 7.2 earthquake, which struck Kamchatka during our study, caused a slight weakening of the rocks due to microstructural damage. We register changes shortly before an eruption and suggest a connection to the beginning of an eruptive cycle in 2016.
    Description: Key Points: Fluctuating noise conditions lead to distortions in noise interferometry studies, which we avoid with the help of machine learning. The seismic velocity on Kamchatka is affected by numerous mechanisms, amongst them environmental, tectonic, and volcanic events. We observe a velocity increase at Bezymianny during February 2016 and link it to the beginning of the eruptive cycle.
    Description: German Research Foundation
    Description: https://doi.org/10.14470/K47560642124
    Description: https://doi.org/10.24381/cds.e2161bac
    Description: https://doi.org/10.5880/GFZ.2.4.2022.002
    Description: https://doi.org/10.5281/zenodo.7481934
    Keywords: ddc:551 ; seismology ; volcano monitoring ; machine learning ; ambient noise ; seismic velocity change ; time varying earth structure
    Language: English
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    The Deep‐Water Plume in the Northwestern Weddell Sea, Antarctica: Mean State, Seasonal Cycle and Interannual Variability Influenced by Climate Modes (2023)
    Details
    Publication Date: 2023-06-21
    Description: We provide an updated estimate of the annual‐mean, seasonal cycle and interannual variability of the transports and properties of the Weddell Sea Bottom Water (WSBW) plume in the northwestern Weddell Sea. For this we used a densely instrumented mooring array deployed across the continental slope between January 2017 and January 2019. We found that the annual‐mean WSBW transport is 3.4 ± 1.5 Sv, corresponding to a cross‐section area of 35 km2 and a maximum thickness of 203 m. The annual mean transport‐weighted properties of WSBW are −0.99°C (Θ), 34.803 g/kg (SA) and 28.44 kg/m3 (γn). The WSBW is characterized by 3 bottom‐intensified velocity cores, which display seasonal variations in flow speed and transport different varieties of WSBW. The seasonal peak of WSBW transport and density is reached in May (4.7 Sv, 28.443 kg m−3) while the minimum values are observed in February (2.8 Sv, 28.435 kg m−3). The coldest WSBW is found between March and May, and the warmest between August and October. The density decrease of WSBW observed in the austral autumn of 2018 can be explained by warmer ambient waters being entrained during the formation of WSBW. This was enabled by the weakening of the along‐shore winds associated with a positive Southern Annular Mode index, reinforced by a La Niña event in early 2018. The synchronous decrease of total WSBW transport and volume between September 2018 and February 2019 indicates a reduction in the export of the dense precursors of WSBW from the Weddell Sea continental shelf.
    Description: Plain Language Summary: The Meridional Overturning Circulation (MOC) redistributes heat and carbon dioxide in the world ocean. Thus, it plays an important role in the regulation of our planet's climate. The Weddell Sea is the main contributor to the deep branch of the MOC in the Southern Hemisphere. Despite the importance of this contribution, uncertainties still remain associated to the plume of dense waters transported along the continental slope of the Weddell Sea. To reduce these uncertainties, we analyzed the most densely instrumented mooring array deployed across the continental slope in the northwestern Weddell Sea. We found that this plume flows faster close to the seafloor and that it presents important seasonal and interannual variability. The Weddell Sea Bottom Water interannual variability is influenced by changes in the along‐shore winds driven by the phase of two important climate modes, the Southern Annular Mode and the El Niño‐Southern Oscillation, but also by changes in the export of the dense precursors of WSBW in its formation areas. Increasing our knowledge on the along‐slope plume variability and properties is important to better understand the causes behind the variability of the MOC observed further downstream.
    Description: Key Points: The Weddell Sea Bottom Water (WSBW) plume presents 3 velocity cores and a clear seasonal cycle, with maximum transports and densities in May and minimum in February. A +SAM, reinforced by a ‐ENSO, favors the warming of WSBW via a wind‐driven warming of the ambient waters entrained during its formation. We observed a marked decrease in WSBW density and transports between September 2018 and February 2019 compared to the previous year.
    Description: EU Horizon 2020 Research and Innovation Program
    Description: German Research Foundation
    Description: Alfred Wegener Institute Helmholtz‐Center
    Description: https://doi.org/10.5281/zenodo.7500163
    Keywords: ddc:551.46 ; Weddell Sea ; WSBW ; Meridional Overturning Circulation ; SAM ; ENSO ; deep‐water plume
    Language: English
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    Testing the success of palaeontological methods in the delimitation of clam shrimp (Crustacea, Branchiopoda) on extant species (2023)
    Hethke, Manja ; Hartmann, Kai ; Alberti, Matthias ; [et al.]
    Details
    Publication Date: 2023-06-21
    Description: Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species‐diagnostic; seven ornamentation types are distinguished of which six are species‐specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5061/dryad.fbg79cnxs
    Keywords: ddc:565 ; clam‐shrimp carapace ; morphometrics ; species delimitation ; Spinicaudata ; Ozestheria ; Australia
    Language: English
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    Paleo‐Hydrogeological Modeling to Understand Present‐Day Groundwater Salinities in a Low‐Lying Coastal Groundwater System (Northwestern Germany) (2023)
    Seibert, Stephan L. ; Greskowiak, Janek ; Bungenstock, Friederike ; [et al.]
    Details
    Publication Date: 2023-06-21
    Description: Groundwater abstraction and drainage are considered to be the main drivers for the salinization of low‐lying coastal groundwater systems, while the role of past boundary conditions is less clear. In this study, 3‐D paleo‐hydrogeological variable‐density groundwater flow and salt transport modeling (“paleo‐modeling”) is applied to reconstruct the evolution of groundwater salinities during the Holocene, that is, the last 9,000 years, in Northwestern Germany. Novel aspects of this study include the consideration of highly resolved time‐variant boundary conditions in a 3‐D paleo‐modeling framework, for example, sea‐level rise, surface elevation and coastline changes, development of drainage networks and groundwater abstraction, as well as the quantification of isolated processes impacting salinization. Results show that salinization was a function of sea‐level rise from 9000 BP until 1300 CE. The creation of the dike line ∼1300 CE set the starting point for increasing anthropogenic control of the hydro(geo)logical system: changes in surface elevation and drainage of low‐lying marshes have become main drivers for salinization after 1600 CE when peat was artificially degenerated. Moreover, changes in the dike line caused by storm floods impacted the salinities. Model results for 2020 CE match well with present‐day salinity observations. Yet, salinization will continue in the future, as the hydro(geo)logical system has not reached an equilibrium. The presented paleo‐modeling framework can be viewed as a blueprint for similar low‐lying coastal groundwater systems, influenced by marine transgression and human development. Thereby, it enables the reconstruction of meaningful present‐day salinity distributions, serving as a vital basis for modeling future groundwater systems in a changing climate.
    Description: Key Points: Salinization of a low‐lying coastal groundwater system during the Holocene, that is, 9000 BP until present‐day, was investigated. Sea‐level rise and the evolution of paleogeography were major controls on groundwater salinization during most of the time. Surface elevation changes due to land cultivation, as well as the development of drainage networks, control salinization since ∼1600 CE.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.5281/zenodo.7633381
    Keywords: ddc:551.49 ; saltwater intrusion ; variable‐density groundwater flow ; salt transport ; sea‐level rise ; parameter estimation ; iMOD‐WQ
    Language: English
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    Horizontal Correlation Functions of Wind Fluctuations in the Mesosphere and Lower Thermosphere (2023)
    Details
    Publication Date: 2023-06-21
    Description: Measurements of kinetic energy in vortical and divergent fluctuations in the mesosphere and lower thermosphere can be used to study stratified turbulence (ST) and gravity waves. This can be done using horizontal correlation functions of the fluctuating component of velocity. This study introduces a novel method for estimating these correlation functions using radars that observe Doppler shifts of ionized specular meteor trails. The technique solves the correlation functions directly on a longitudinal‐transverse‐up coordinate system, assuming axial symmetry. This procedure is more efficient and leads to smaller uncertainties than a previous approach. The new technique is applied to a year‐long data set from a multistatic specular meteor radar network in Germany, to study the annual variability of kinetic energy within turbulent fluctuations at 87–93 km of altitude. In monthly averages, the kinetic energy is found to be nearly equipartitioned between vortical and divergent modes. Turbulent fluctuations maximize during the winter months with approximately 25% more energy in these months than at other times. The horizontal correlation functions are in agreement with the inertial subrange of ST, exhibiting a 2/3 power law in the horizontal lag direction, with an outermost scale of ST to be about 380 km. This suggests that horizontal correlation functions could be used to estimate turbulent energy transfer rates.
    Description: Plain Language Summary: Flows exhibit a phenomenon called turbulence, which transfers energy from large scales into smaller scales. This effect is important to quantify the energy budget of the Earth's upper atmosphere. The range of length scales where this phenomenon occurs is called the inertial subrange of turbulence. The classical theory of isotropic turbulence predicts that this energy transfer occurs on length scales smaller than ∼100 m, at 60–110 km altitude. Recent work has shown that horizontal velocity fluctuations can extend the inertial subrange to length scales of up to hundreds of kilometers horizontally. This type of turbulence is called stratified turbulence (ST). So far no comprehensive study has been made to experimentally examine ST in the mesosphere and lower thermosphere (MLT) region on horizontal mesoscales. This study introduces a method for doing so by measuring how the wind fluctuations are correlated as a function of horizontal separation. This is achieved by using meteor radar measurements. The technique is applied to a year‐long data set over Germany. It is found that the MLT wind fluctuations are compatible with ST theory. The introduced method could potentially be used for routinely measuring how kinetic energy flows from large‐scale to small‐scale atmospheric fluctuations.
    Description: Key Points: A more efficient estimator for horizontal correlation functions is introduced. The rotational and divergent correlation functions of mesosphere and lower thermosphere wind fluctuations are found to be balanced at horizontal mesoscales. Horizontal correlations of wind fluctuations follow a 2/3‐power law for horizontal separations of up to 300–400 km.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: French Ministry of Foreign and European Affairs
    Description: Leibniz SAW project FORMOSA
    Keywords: ddc:551.5 ; mesosphere ; lower thermosphere ; wind fluctuations
    Language: English
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    The Global Seismic Moment Rate of Mars After Event S1222a (2023)
    Details
    Publication Date: 2023-07-20
    Description: The seismic activity of a planet can be described by the corner magnitude, events larger than which are extremely unlikely, and the seismic moment rate, the long‐term average of annual seismic moment release. Marsquake S1222a proves large enough to be representative of the global activity of Mars and places observational constraints on the moment rate. The magnitude‐frequency distribution of relevant Marsquakes indicates a $b$‐value of 1.06. The moment rate is likely between $1.55\times {10}^{15}\mathrm{N}\mathrm{m}/\mathrm{a}$ and $1.97\times {10}^{18}\mathrm{N}\mathrm{m}/\mathrm{a}$, with a marginal distribution peaking at $4.9\times {10}^{16}\mathrm{N}\mathrm{m}/\mathrm{a}$. Comparing this with pre‐InSight estimations shows that these tended to overestimate the moment rate, and that 30% or more of the tectonic deformation may occur silently, whereas the seismicity is probably restricted to localized centers rather than spread over the entire planet.
    Description: Plain Language Summary: The seismic moment rate is a measure for how fast quakes accumulate deformation of the planet's rigid outer layer, the lithosphere. In the past decades, several models for the deformation rate of Mars were developed either from the traces quakes leave on the surface, or from mathematical models of how quickly the planet's interior cools down and shrinks. The large marsquake that occurred on the 4th of May 2022 now allows a statistical estimation of the deformation accumulated on Mars per year, and thus to confront these models with reality. It turns out that, although there is a considerable overlap, the models published prior to InSight tend to overestimate the seismic moment rate, and hence the ongoing deformation on Mars. Possible explanations are that 30% or more of the deformation occurs silently, that is, without causing quakes, or that not the entire planet is seismically active but only specific regions.
    Description: Key Points: A single large marsquake suffices to constrain the global seismic moment rate. Pre‐InSight estimations tended to overestimate the moment rate. Either a significant part of the ongoing deformation occurs silent, or seismic activity is restricted to some activity centers, or both.
    Description: Eidgenössische Technische Hochschule Zürich http://dx.doi.org/10.13039/501100003006
    Description: National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
    Description: UK Space Agency http://dx.doi.org/10.13039/100011690
    Description: Deutsches Zentrum für Luft‐ und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: Insight SFI Research Centre for Data Analytics http://dx.doi.org/10.13039/501100021525
    Description: http://dx.doi.org/10.18715/SEIS.INSIGHT.XB_2016
    Description: http://doi.org/10.17189/1517570
    Keywords: ddc:523 ; Mars ; InSight ; seismic moment rate ; S1222a
    Language: English
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    Use of electron backscatter diffraction patterns to determine the crystal lattice. Part 3. Pseudosymmetry (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-07-20
    Description: A pseudosymmetric description of the crystal lattice derived from a single wide‐angle Kikuchi pattern can have several causes. The small size (〈15%) of the sector covered by an electron backscatter diffraction pattern, the limited precision of the projection centre position and the Kikuchi band definition are crucial. Inherent pseudosymmetries of the crystal lattice and/or structure also pose a challenge in the analysis of Kikuchi patterns. To eliminate experimental errors as much as possible, simulated Kikuchi patterns of 350 phases have been analysed using the software CALM [Nolze et al. (2021). J. Appl. Cryst.54, 1012–1022] in order to estimate the frequency of and reasons for pseudosymmetric crystal lattice descriptions. Misinterpretations occur in particular when the atomic scattering factors of non‐equivalent positions are too similar and reciprocal‐lattice points are systematically missing. As an example, a pseudosymmetry prediction depending on the elements involved is discussed for binary AB compounds with B1 and B2 structure types. However, since this is impossible for more complicated phases, this approach cannot be directly applied to compounds of arbitrary composition and structure.
    Description: Distinguishing between actual and apparent pseudosymmetry in electron backscatter diffraction patterns is nearly impossible, even for simulated patterns. However, the resulting lattice is always a superlattice as long as the signal is not a superposition of multiple patterns.
    Keywords: ddc:548 ; Bravais lattices ; pseudosymmetry ; lattice point density ; ordered/disordered structures ; lattice distortion ; electron backscatter diffraction ; backscattered Kikuchi diffraction patterns ; lattice parameters ; Funk transform
    Language: English
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    Late Miocene Exhumation of the Western Cordillera, Ecuador, Driven by Increased Coupling Between the Subducting Carnegie Ridge and the South American Continent (2023)
    Details
    Publication Date: 2023-07-20
    Description: The subduction of bathymetric highs, such as aseismic ridges, leads to far‐reaching changes in the dynamics of subduction zones with increased plate coupling and deformation in the upper plate. Subduction of the submarine Carnegie Ridge on the Nazca Plate has fundamentally impacted late Cenozoic magmatism and tectonic activity in the northern Andes. However, the timing of onset of Carnegie Ridge subduction has been a matter of debate. Time‐temperature inverse modeling of new thermochronological data from the Western Cordillera of Ecuador reveals two phases of cooling separated by isothermal conditions. The first cooling phase postdates early and middle Miocene magmatism in the Western Cordillera and is attributed to post‐magmatic thermal relaxation. The second cooling phase started after 6 Ma. Inferred to record the onset of tectonically controlled rock uplift and exhumation in the Western Cordillera, this phase is coeval with the last cooling phase recorded in the Eastern Cordillera. Based on these findings, we suggest that the onset of subduction of the Carnegie Ridge at ∼6–5 Ma increased plate coupling at the subduction interface, promoting shortening, regional rock uplift, and exhumation in the northern Andes. Overall, our results highlight the essential role of bathymetric highs in driving regional upper‐plate deformation at non‐collisional convergent plate margins.
    Description: Plain Language Summary: Topographic growth and morphology of the Andes have been influenced by subduction processes, tectonic inheritance, and climate. Here, we investigate the role of subduction of high topography on the ocean floor in driving deformation in the upper plate at the Nazca‐South America ocean‐continent plate margin. The subduction of the Carnegie Ridge, a linear, topographically high sector on the Nazca Plate, has impacted magmatism and deformation processes in the Ecuadorian Andes. However, the timing of onset of ridge subduction is debated. We employed radioisotopic dating techniques to evaluate the uplift of the Andes. These techniques record the cooling of rocks as mountain ranges are uplifted and eroded. The thermal histories of rocks from the Western Cordillera in Ecuador reveal two distinct cooling phases. The first cooling phase occurred shortly after Miocene magmatic bodies were emplaced in the Western Cordillera. The second cooling phase began at ∼6–5 Ma, coeval with the last cooling phase in the Eastern Cordillera. We attribute this cooling phase to the onset of uplift and erosion in the Western Cordillera. Based on these findings, we suggest that the onset of subduction of the Carnegie Ridge increased plate coupling and promoted shortening and rock uplift in the northern Andes.
    Description: Key Points: Thermochronological data reveal two cooling phases in the Western Cordillera of Ecuador, during the Miocene and after 6 Ma. The onset of cooling at 6 Ma was associated with shortening, rock uplift, and exhumation in the Western Cordillera. Mio‐Pliocene exhumation was related to stronger coupling of the subduction interface due to the initial subduction of the Carnegie Ridge.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Potsdam University Graduate School
    Description: Yachay Tech University
    Description: Arizona LaserChron Center
    Description: https://zenodo.org/record/7311529#Y4YTYYLMITU
    Keywords: ddc:551.8 ; aseismic ridge subduction ; topographic growth ; zircon U‐Pb geochronology ; apatite and zircon (U‐Th)/He and apatite fission‐track thermochronology ; Carnegie ridge ; northern Andes
    Language: English
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    Structure and Dynamics of Lithosphere and Asthenosphere in Asia: A Seismological Perspective (2023)
    Details
    Publication Date: 2023-07-20
    Description: Knowledge of lithospheric structure is essential for understanding the impact of continental collision and oceanic subduction on surface tectonic configurations. Full‐waveform tomographic images reveal lateral heterogeneities and anisotropy of the lithosphere and asthenosphere in Asia. Estimating lithospheric thickness from seismic velocity reductions at depth exhibits large variations underneath different tectonic units. The thickest cratonic roots are present beneath the Sichuan, Ordos, and Tarim basins and central India. Radial anisotropy signatures of 11 representative tectonic provinces uncover the different nature and geodynamic processes of their respective past and present deformation. The large‐scale continental lithospheric deformation is characterized by low‐velocity anomalies from the Himalayan Orogen to the Baikal rift zone in central Asia, coupled with the post‐collision thickening of the crust. The horizontal low‐velocity layer of ∼100–300 km depth extent below the lithosphere points toward the existence of the asthenosphere beneath East and Southeast Asia, with heterogeneous anisotropy indicative of channel flows.
    Description: Plain Language Summary: The lithospheric plates, like mosaics of the Earth’s surface, are moving coherently over the weaker, convecting asthenosphere. The lithospheric structure and thickness dictated by mantle dynamics play a first‐order role in understanding the active tectonics and morphological evolution of the Asian region. Here, the latest high‐resolution full‐waveform tomographic model, SinoScope 1.0, is employed to investigate the seismic structure and dynamics of the lithosphere and asthenosphere from a seismological perspective. The lithospheric thickness of known various geological units and cratonic blocks is retrieved with large variability. The observed anisotropic signatures within the lithosphere and asthenosphere provide important constraints on the deformation state and history of different tectonic provinces. The India‐Eurasia collision primarily induced large‐scale lithospheric deformation and thickening of the crust in the west of the North‐South Gravity Lineament. The narrow low‐velocity layer below the lithosphere lies beneath East and Southeast Asia and is bounded by subduction trenches and cratonic blocks, which provides seismic evidence for the low‐viscosity asthenosphere that partially decouples plates from mantle flow beneath and allows plate tectonics to work above. The lithospheric thinning and extension, intensive magmatism, and mineralization are potentially associated with the strong interaction between the lithosphere and asthenospheric flow in the eastern Asian margin.
    Description: Key Points: Full‐waveform tomographic images reveal lateral heterogeneities and anisotropy in the lithosphere and asthenosphere beneath the Asian region. India‐Eurasia collision induced large‐scale low‐velocity anomaly and crustal thickening spanning from the Himalayas to the Baikal rift zone. Asthenosphere in East and SE Asia exhibits strong vsh, 〉 vsv, and partially decouples lithosphere, bounded by subduction trench and cratonic keels.
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: Korea Meteorological Administration Research and Development Program http://dx.doi.org/10.13039/501100003629
    Description: National Research Foundation of Korea http://dx.doi.org/10.13039/501100003725
    Keywords: ddc:551.1 ; Asia ; seismic structure ; lithosphere dynamics ; asthenosphere dynamics
    Language: English
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    The Sensitivity of Moisture Flux Partitioning in the Cold‐Point Tropopause to External Forcing (2023)
    Details
    Publication Date: 2023-07-20
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The dryness of the stratosphere is the result of air entering through the cold tropical tropopause layer (TTL). However, our understanding of the moisture flux partitioning into water vapor and frozen hydrometeors is incomplete. This raises concerns regarding the ability of General Circulation Models to accurately predict changes in stratospheric water vapor following perturbations in the radiative budget due to volcanic aerosol or stratospheric geoengineering. We present the first results using a global storm‐resolving model investigating the sensitivity of moisture fluxes within the TTL to an additional heating source. We address the question how the partitioning of moisture fluxes into water vapor and frozen hydrometeors changes under perturbations. The analysis reveals the resilience of the TTL, keeping the flux partitioning constant even at an average cold‐point warming exceeding 8 K. In the control and perturbed simulations, water vapor contributes around 80% of the moisture entering the stratosphere.〈/p〉
    Description: Plain Language Summary: The stratosphere is a dry region since moisture entering it from below has to pass the cold‐point, a temperature minimum between troposphere and stratosphere. The low temperatures lead to ice formation and sedimentation of moisture. Frozen moisture within clouds rising above the cold‐point tropopause can pass this temperature barrier and be injected into the stratosphere, where temperatures increase again, promoting the melting and sublimation of ice crystals. However, little is known about the sensitivity of the split of moisture entering the stratosphere into frozen and non‐frozen moisture, especially under external influences, like heating by volcanic aerosol or stratospheric geoengineering efforts. Convective parameterizations in conventional simulations can lead to biases. The emerging km‐scale simulations, which explicitly resolve the physical processes, offer the unique possibility to study moisture fluxes under external forcing while circumventing the downsides of parameterizations. Here, the sensitivity of the moisture flux partitioning into non‐frozen and frozen components to an additional heating source is studied for the first time in global storm‐resolving simulations. The analysis reveals an unaltered flux partitioning even at an average cold‐point warming exceeding 8 K. In the control and perturbed simulations, water vapor contributes around 80% of the moisture entering the stratosphere.〈/p〉
    Description: Key Points:Water vapor dominates the stratospheric moisture budget with a contribution of around 80% in global storm‐resolving simulation. The partitioning of stratospheric moisture fluxes into vapor and frozen hydrometeors remains stable under large temperature perturbations.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Fueglistaler Group
    Keywords: ddc:551.5 ; stratospheric water vapor ; tropopause ; perturbation ; moisture budget ; geoengineering ; volcano
    Language: English
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    Discriminating Aromatic Parent Compounds and Their Derivative Isomers in Ice Grains From Enceladus and Europa Using a Laboratory Analogue for Spaceborne Mass Spectrometers (2023)
    Details
    Publication Date: 2023-07-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Results from the Cassini‐Huygens space mission at Enceladus revealed a substantial inventory of organic species embedded in plume and E ring ice grains originating from a global subsurface and putative habitable ocean. Compositional analysis by the Cosmic Dust Analyzer indicated the presence of aromatic species and constrained some structural features, although their exact nature remains unclear. As indicated by many studies, among other organic species, low‐mass aromatics likely played a role in the emergence of life on Earth and may be linked to potential prebiotic or biogenic chemistry on icy moons. Here, we study the behavior of single‐ringed aromatic compounds—benzoic acid and two isomeric derivatives, 2,3‐dihydroxybenzoic acid and 2,5‐dihydroxybenzoic acid—using Laser‐Induced Liquid Beam Ion Desorption (LILBID), an analogue setup to simulate the impact ionization mass spectra of ice grains in space. These compounds share common structural features but also exhibit differences in functional groups and substituent positions. We investigate the fragmentation behavior and spectral appearance of each molecule over three simulated impact velocities, in both positive and negative ion modes. Parent compounds can be distinguished easily from their derivatives due to various spectral differences, including the (de)protonated molecular ion peaks appearing at different 〈italic〉m〈/italic〉/〈italic〉z〈/italic〉 values. We conclude that distinction between structural isomers in LILBID is more challenging, but some insights can be revealed by considering intermolecular bonding regimes. This work will guide future investigations into elucidating the composition of isomeric biosignatures in ice grains, relevant for future space missions to Enceladus and Europa.〈/p〉
    Description: Plain Language Summary: The Cassini‐Huygens space mission discovered a plume at Enceladus that ejects gases and frozen ice grains originating from an ocean of liquid water below its icy shell. In these ice grains, a range of interesting organic molecules were discovered by Cassini's Cosmic Dust Analyzer mass spectrometer. Organic molecules are important in the search for life beyond Earth as they form the basis of all known Earth life, and active biology elsewhere would likely have a discernible effect on the local inventory of organic species. One class of organic, with a ring structure of carbon atoms, called aromatics, were discovered in the plume. We investigate the spectral appearance of one example of aromatic compound, benzoic acid, as well as two similar compounds with additional chemical groups attached to the aromatic ring. The two similar compounds have the same mass and general structure, but slightly different arrangements of the additional groups, known as isomers. We find that it is simple to distinguish mass spectral features between benzoic acid and its related compounds, but more difficult to explain the differences between the isomers. This work will assist the analysis of mass spectrometry data from future habitability‐investigating space missions to ocean‐bearing icy moons.〈/p〉
    Description: Key Points: Cassini revealed a variety of organic compounds including clear evidence of aromatics in the plume of Enceladus. Identifying mass spectral features of isomeric organics enhances our ability to assess the astrobiological potential of Enceladus/Europa. Parent aromatic compounds can be easily distinguished from their derivatives in ice grains with impact ionization mass spectrometry.
    Description: European Research Council Consolidator
    Description: http://dx.doi.org/10.17169/refubium-37960
    Description: https://lilbid-db.planet.fu-berlin.de/
    Keywords: ddc:523 ; mass spectrometry ; LILBID and impact ionization ; aromatics and isomeric derivatives ; Enceladus and Europa ; space missions ; habitability
    Language: English
    Type: doc-type:article
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  • 99
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    The Zenith‐Angle Dependence of the Downward Radiation Dose Rate on the Martian Surface: Modeling Versus MSL/RAD Measurement (2023)
    Details
    Publication Date: 2023-07-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Radiation Assessment Detector (RAD) on board the Mars Science Laboratory's Curiosity rover has been monitoring the surface radiation environment on Mars for just over 10 years. It has been found by Wimmer‐Schweingruber et al. (2015, 〈ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1002/2015gl066664"〉https://doi.org/10.1002/2015gl066664〈/ext-link〉) that within the narrow view cone of RAD, the directionality of the radiation field is close to but not completely isotropic. In order to better understand the directionality of the surface radiation over a wide range of zenith angles (〈italic〉θ〈/italic〉), we perform a three‐dimensional Geant4 Monte Carlo simulation to derive the 〈italic〉θ〈/italic〉‐dependence of the surface dose rate. The results show that galactic cosmic ray protons, coming in at 〈italic〉θ〈/italic〉 ∼ 74° make the greatest contribution to the surface dose. For helium ions, this angle is at around 46°. This is a consequence of the increasing column depth at larger zenith angles and the complex interplay of the destruction of primary and the creation of secondary particles as the primary cosmic ray interacts with the Martian atmosphere. We also compared the simulated results with the RAD measurements and found a reasonable agreement. Our results are important for future human exploration of Mars, for instance, to estimate the effectiveness of radiation shielding of a given geometry or for optimizing the radiation shielding design of a Martian habitat.〈/p〉
    Description: Plain Language Summary: Space agencies and private companies are working to place humans on the surface of Mars. Astronauts would be exposed to a different and considerably harsher radiation environment on Mars than humans are on Earth. Space radiation is largely determined by galactic cosmic rays, which have sufficient energy to reach the Martian surface. Thus, a better understanding of the radiation on the surface of Mars is needed. The shielding provided by the atmosphere increases with the zenith angle, and it also causes an increase in the creation of secondary particles. To better understand this, we perform a Geant4 Monte Carlo simulation to derive the dependence of the surface dose rate on the zenith angle 〈italic〉θ〈/italic〉. The results show that the radiation dose on the surface of Mars depends on the incoming angle of the primary radiation. Moreover, the radiation dose rate is significantly modulated by solar activity, and the Mars surface dose rate differs by about 50% between solar maximum and minimum periods. We validate our simulation by comparing the dose measured by the Mars Science Laboratory Radiation Assessment Detector and find good agreement.〈/p〉
    Description: Key Points: We model the downward radiation dose on the surface of Mars and find that it only depends weakly on the zenith angle. The surface dose rate depends on solar modulation, and weaker modulation results in higher dose rate for each.The local topographical features influence the Martian surface radiation.
    Description: Deutsches Zentrum für Luft‐und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: Jet Propulsion Laboratory http://dx.doi.org/10.13039/100006196
    Description: Strategic Priority Program of CAS
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: Civil Aerospace Technologies
    Description: NASA Johnson Space Center
    Description: https://doi.org/10.17189/1519761
    Description: https://doi.org/10.17189/1519760
    Description: https://doi.org/10.17189/1523028
    Description: https://doi.org/10.5281/zenodo.7257306
    Keywords: ddc:523 ; space radiation ; Mars exploration ; MSL mission ; zenith angle
    Language: English
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  • 100
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    The Temperature and Composition of the Mantle Sources of Martian Basalts (2023)
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    Publication Date: 2023-07-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The composition of basaltic melts in equilibrium with the mantle can be determined for several Martian meteorites and in‐situ rover analyses. We use the melting model MAGMARS to reproduce these primary melts and estimate the bulk composition and temperature of the mantle regions from which they originated. We find that most mantle sources are depleted in CaO and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 relative to models of the bulk silicate Mars and likely represent melting residues or magma ocean cumulates. The concentrations of Na〈sub〉2〈/sub〉O, K〈sub〉2〈/sub〉O, P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉, and TiO〈sub〉2〈/sub〉 are variable and often less depleted, pointing to the re‐fertilization of the sources by fluids and low‐degree melts, or the incorporation of residual trapped melts during the crystallization of the magma ocean. The mantle potential temperatures of the sources are 1400–1500°C, regardless of the time at which they melted and within the range of the most recent predictions from thermochemical evolution models.〈/p〉
    Description: Plain Language Summary: Martian meteorites and rocks analyzed by rovers are witnesses of magmatic processes on Mars. Some of the basaltic specimens among them have been classified as “primitive” as they are closely related to the melts that form in the mantle and feature high MgO/FeO. They record important properties of the mantle of Mars. We use the mantle melting model MAGMARS to constrain the temperature and composition of the mantle source regions from which primitive basalts originated. We find that the mantle compositions were low in CaO and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, either because they melted on several occasions, or because these components were locked in deeper layers of the mantle when it solidified from the bottom up (early magma ocean). Several mantle sources are comparatively rich in Na〈sub〉2〈/sub〉O, K〈sub〉2〈/sub〉O, P〈sub〉2〈/sub〉O〈sub〉5〈/sub〉, and TiO〈sub〉2〈/sub〉. These components were either subsequently added to the mantle sources by fluids and low‐degree melts or can be explained by the trapping of melts during the progressive crystallization of the magma ocean. The temperature of the mantle sources projected to surface conditions for easier comparison (potential temperature) was 1400–1500°C, regardless of the time at which they melted, and is within the range of recent predictions from planetary‐scale models of interior dynamics.〈/p〉
    Description: Key Points: Basalts that sampled discrete mantle regions throughout Mars's history provide information about the mantle composition and temperature. The mantle potential temperature of primitive basalts appears constant (1400–1500ºC), yet is likely not representative of the average mantle. Incompatible element concentrations in the mantle vary due to magma ocean crystallization, partial melting, and metasomatism.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Deutsches Zentrum für Luft‐ und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: https://doi.org/10.5281/zenodo.7949084
    Keywords: ddc:552 ; Martian magmatism ; mantle melting ; Mars interior structure ; depleted mantle ; metasomatism ; secular cooling
    Language: English
    Type: doc-type:article
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