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  • 101
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    On the evaluation of climate change impact models (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-08-05
    Description: In‐depth understanding of the potential implications of climate change is required to guide decision‐ and policy‐makers when developing adaptation strategies and designing infrastructure suitable for future conditions. Impact models that translate potential future climate conditions into variables of interest are needed to create the causal connection between a changing climate and its impact for different sectors. Recent surveys suggest that the primary strategy for validating such models (and hence for justifying their use) heavily relies on assessing the accuracy of model simulations by comparing them against historical observations. We argue that such a comparison is necessary and valuable, but not sufficient to achieve a comprehensive evaluation of climate change impact models. We believe that a complementary, largely observation‐independent, step of model evaluation is needed to ensure more transparency of model behavior and greater robustness of scenario‐based analyses. This step should address the following four questions: (1) Do modeled dominant process controls match our system perception? (2) Is my model's sensitivity to changing forcing as expected? (3) Do modeled decision levers show adequate influence? (4) Can we attribute uncertainty sources throughout the projection horizon? We believe that global sensitivity analysis, with its ability to investigate a model's response to joint variations of multiple inputs in a structured way, offers a coherent approach to address all four questions comprehensively. Such additional model evaluation would strengthen stakeholder confidence in model projections and, therefore, into the adaptation strategies derived with the help of impact models.
    Description: A comprehensive evaluation of climate change impact models combining both observation‐based and response‐based strategies.
    Description: This article is categorized under: Climate Models and Modeling 〉 Knowledge Generation with Models Assessing Impacts of Climate Change 〉 Evaluating Future Impacts of Climate Change
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266
    Keywords: ddc:551.6
    Language: English
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  • 102
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    The ICON Earth System Model Version 1.0 (2022)
    Details
    Publication Date: 2022-08-05
    Description: This work documents the ICON‐Earth System Model (ICON‐ESM V1.0), the first coupled model based on the ICON (ICOsahedral Non‐hydrostatic) framework with its unstructured, icosahedral grid concept. The ICON‐A atmosphere uses a nonhydrostatic dynamical core and the ocean model ICON‐O builds on the same ICON infrastructure, but applies the Boussinesq and hydrostatic approximation and includes a sea‐ice model. The ICON‐Land module provides a new framework for the modeling of land processes and the terrestrial carbon cycle. The oceanic carbon cycle and biogeochemistry are represented by the Hamburg Ocean Carbon Cycle module. We describe the tuning and spin‐up of a base‐line version at a resolution typical for models participating in the Coupled Model Intercomparison Project (CMIP). The performance of ICON‐ESM is assessed by means of a set of standard CMIP6 simulations. Achievements are well‐balanced top‐of‐atmosphere radiation, stable key climate quantities in the control simulation, and a good representation of the historical surface temperature evolution. The model has overall biases, which are comparable to those of other CMIP models, but ICON‐ESM performs less well than its predecessor, the Max Planck Institute Earth System Model. Problematic biases are diagnosed in ICON‐ESM in the vertical cloud distribution and the mean zonal wind field. In the ocean, sub‐surface temperature and salinity biases are of concern as is a too strong seasonal cycle of the sea‐ice cover in both hemispheres. ICON‐ESM V1.0 serves as a basis for further developments that will take advantage of ICON‐specific properties such as spatially varying resolution, and configurations at very high resolution.
    Description: Plain Language Summary: ICON‐ESM is a completely new coupled climate and earth system model that applies novel design principles and numerical techniques. The atmosphere model applies a non‐hydrostatic dynamical core, both atmosphere and ocean models apply unstructured meshes, and the model is adapted for high‐performance computing systems. This article describes how the component models for atmosphere, land, and ocean are coupled together and how we achieve a stable climate by setting certain tuning parameters and performing sensitivity experiments. We evaluate the performance of our new model by running a set of experiments under pre‐industrial and historical climate conditions as well as a set of idealized greenhouse‐gas‐increase experiments. These experiments were designed by the Coupled Model Intercomparison Project (CMIP) and allow us to compare the results to those from other CMIP models and the predecessor of our model, the Max Planck Institute for Meteorology Earth System Model. While we diagnose overall satisfactory performance, we find that ICON‐ESM features somewhat larger biases in several quantities compared to its predecessor at comparable grid resolution. We emphasize that the present configuration serves as a basis from where future development steps will open up new perspectives in earth system modeling.
    Description: Key Points: This work documents ICON‐ESM 1.0, the first version of a coupled model based on the ICON framework. Performance of ICON‐ESM is assessed by means of CMIP6 Diagnosis, Evaluation, and Characterization of Klima experiments at standard CMIP‐type resolution. ICON‐ESM reproduces the observed temperature evolution. Biases in clouds, winds, sea‐ice, and ocean properties are larger than in MPI‐ESM.
    Description: European Union H2020 ESM2025
    Description: European Union H2020 COMFORT
    Description: European Union H2020ESiWACE2
    Description: Deutsche Forschungsgemeinschaft TRR181
    Description: Deutsche Forschungsgemeinschaft EXC 2037
    Description: European Union H2020
    Description: Deutscher Wetterdienst
    Description: Bundesministerium fuer Bildung und Forschung
    Description: http://esgf-data.dkrz.de/search/cmip6-dkrz/
    Description: https://mpimet.mpg.de/en/science/modeling-with-icon/code-availability
    Description: http://cera-www.dkrz.de/WDCC/ui/Compact.jsp?acronym=RUBY-0_ICON-_ESM_V1.0_Model
    Keywords: ddc:550.285 ; ddc:551.63
    Language: English
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  • 103
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    Olivine aggregates reveal a complex collisional history of the main group pallasite parent body (2022)
    Details
    Publication Date: 2022-08-05
    Description: Olivine aggregates, bodies found in pallasites that consist of olivines with coherent grain boundaries and minor amounts of Fe‐Ni and troilite, likely represent well‐preserved samples of different mantle regions of pallasite parent bodies (PPBs). We investigated olivine aggregates from the main group pallasites Fukang, Esquel, Imilac, and Seymchan and compare their textures with results from deformation experiments. Our measurements reveal an inverse relationship between the grain size of olivines and the primary metal fraction inside olivine aggregates, which is explained by simultaneous grain growth retarded by Zener pinning in different mantle regions. Textural evidence indicates that the mantle has remained at high temperatures before initial cooling occurred shortly after pallasite formation that was likely caused by an impact. Different degrees of annealing of the deformation textures suggest that the postcollisional cooling occurred in the order Seymchan, Imilac, Esquel, and Fukang. We interpret this observation with an increasing burial depth after the collision. We also demonstrate that the mantle has not been convecting before the impact despite being at high temperature. Using the minimum critical Rayleigh number, we estimate PPB radii assuming different core radii. Our results question the recent ferromagmatism hypothesis for pallasite formation and support a multistage formation process that includes one or several impacts.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:549.1
    Language: English
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  • 104
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    Plate corner subduction and rapid localized exhumation: Insights from 3D coupled geodynamic and geomorphological modelling (2022)
    Details
    Publication Date: 2022-08-05
    Description: Rapid, localized exhumation has been reported at many plate corners between adjacent subduction/collision segments. Here we use a fully‐coupled geodynamic and geomorphological modelling approach to investigate overriding plate deformation and resulting rock uplift patterns in these narrow, cuspate regions. In this study, we focus on the effects of internal deformation within a subducting convex‐upward‐shaped indenter and the strength of the interface between the upper and downgoing plate. The strongest localization of high rock uplift rates in the region above the indenter apex is predicted in experiments with a deformable lower plate, a weak interface layer and lateral shortening accommodated only by subduction (i.e., without an upper plate advance component). Our results suggest that bull’s eye shaped structures characterized by young thermochronological ages can, in principle, be reproduced numerically when taking into account a non‐rigid subducting plate together with complex brittle‐ductile rheology and stratification of the overriding lithosphere and realistically implemented fluvial erosion at its surface.
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: European Research Council http://dx.doi.org/10.13039/100010663
    Keywords: ddc:551.1
    Language: English
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  • 105
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    Strengths and limitations of in situ U–Pb titanite petrochronology in polymetamorphic rocks: An example from western Maine, USA (2022)
    Details
    Publication Date: 2022-09-27
    Description: Titanite is a potentially powerful U–Pb petrochronometer that may record metamorphism, metasomatism, and deformation. Titanite may also incorporate significant inherited Pb, which may lead to inaccurate and geologically ambiguous U–Pb dates if a proper correction is not or cannot be applied. Here, we present laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS)‐derived titanite U–Pb dates and trace element concentrations for two banded calcsilicate gneisses from south‐central Maine, USA (SSP18‐1A and SSP18‐1B). Single spot common Pb‐corrected dates range from 400 to 280 Ma with ±12–20 Ma propagated 2SE. Titanite grains in sample SSP18‐1B exhibit regular core‐to‐rim variations in texture, composition, and date. We identify four titanite populations: (1) 397 ± 5 Ma (95% CL) low Y + HREE cores and mottled grains, (2) 370 ± 7 Ma high Y + REE mantles and cores, (3) 342 ± 6 Ma cores with high Y + REE and no Eu anomaly, and (4) 295 ± 6 Ma LREE‐depleted rims. We interpret the increase in titanite Y + HREE between ca. 397 and ca. 370 Ma to constrain the timing of diopside fracturing and recrystallization and amphibole breakdown. Apparent Zr‐in‐titanite temperatures (803 ± 36°C at 0.5 ± 0.2 GPa) and increased XDi suggest a thermal maximum at ca. 370 Ma. Population 3 domains dated to ca. 342 Ma exhibit no Eu anomaly and are observed only in compositional bands dominated by diopside (〉80 vol%), suggesting limited equilibrium between titanite and plagioclase. Finally, low LREE and high U/Th in Population 4 titanite dates the formation of hydrous phases, such as allanite, during high XH2O fluid infiltration at ca. 295 Ma. In contrast to the well‐defined date–composition–texture relationships observed for titanite from SSP18‐1B, titanite grains from sample SSP18‐1A exhibit complex zoning patterns and little correlation between texture, composition, and date. We hypothesize that the incorporation of variable amounts of radiogenic Pb from dissolved titanite into recrystallized domains resulted in mixed dates spanning 380–330 Ma. Although titanite may reliably record multiple phases of metamorphism, these data highlight the importance of considering U–Pb data along with chemical and textural data to screen for inherited radiogenic Pb.
    Description: The University of Maine
    Description: US‐DE Fulbright Komission
    Keywords: ddc:552.4
    Language: English
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  • 106
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    Mesocrystalline Architecture in Hyaline Foraminifer Shells Indicates a Non‐Classical Crystallisation Pathway (2022)
    Details
    Publication Date: 2022-09-27
    Description: Calcareous foraminifer shells (tests) represent one of the most important archives for paleoenvironmental and paleoclimatic reconstruction. To develop a mechanistic understanding of the relationship between environmental parameters and proxy signals, knowledge of the fundamental processes operating during foraminiferal biomineralization is essential. Here, we apply microscopic and diffraction‐based methods to address the crystallographic and hierarchical structure of the test wall of different hyaline foraminifer species. Our results show that the tests are constructed from micrometer‐scale oriented mesocrystals built of nanometer‐scale entities. Based on these observations, we propose a mechanistic extension to the biomineralization model for hyaline foraminifers, centered on the formation and assembly of units of metastable carbonate phases to the final mesocrystal via a non‐classical particle attachment process, possibly facilitated by organic matter. This implies the presence of metastable precursors such as vaterite or amorphous calcium carbonate, along with phase transitions to calcite, which is relevant for the mechanistic understanding of proxy incorporation in the hyaline foraminifers.
    Description: Plain Language Summary: Foraminifers are single celled marine organisms typically half a millimeter in size, which form shells made of calcium carbonate. During their life, the chemical composition of their shells records environmental conditions. By analyzing fossil shells, past conditions can be reconstructed to understand ancient oceans and climate change. To do that correctly, we need to know exactly how foraminifers form their shell. We find that foraminifers build micrometer‐sized mesocrystals which are made of smaller building blocks. This means that the smallest building blocks form first and assemble to form a larger grain, which is oriented in a specific direction. To align all the building blocks, it is possible that they are first unstable and undergo transformation on assembly, during which their composition may change. By understanding and quantifying this process, the composition of the final fossil shell may be understood, ultimately leading to more reliable reconstructions of past environmental change.
    Description: Key Points: Hyaline foraminiferal shells are built of micrometer sized mesocrystalline units. Biomineralization likely includes the formation and assembly of nanoparticles. Nanometer sized units suggest non‐classical crystal growth.
    Description: https://doi.org/10.17617/3.D7HN3I
    Keywords: ddc:561.9 ; ddc:549
    Language: English
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  • 107
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    Lagrangian Analysis of Moisture Sources of Precipitation in the Tianshan Mountains, Central Asia (2022)
    Details
    Publication Date: 2022-09-27
    Description: The moisture sources of precipitation in the Tianshan Mountains, one of the regions with the highest precipitation in Central Asia during 1979–2017 are comprehensively and quantitatively summarized by using a Lagrangian moisture source detection technique. Continental sources provide about 93.2% of the moisture for precipitation in the Tianshan Mountain, while moisture directly from the ocean is very limited, averaging only 6.8%. Central Asia plays a dominant role in providing moisture for all sub‐regions of the Tianshan Mountains. For the Western Tianshan, moisture from April to October comes mainly from Central Asia (41.4%), while moisture from November to March is derived primarily from Western Asia (45.7%). Nearly 13.0% of moisture to precipitation for Eastern Tianshan in summer originates from East and South Asia, and the Siberia region. There is a significant decreasing trend in the moisture contribution of local evaporation and Central Asia in the Eastern Tianshan during winter. The contribution of moisture from Europe to summer precipitation in the Central and Eastern Tianshan and the contribution of the North Atlantic Ocean to summer precipitation in the Northern, Central, and Eastern Tianshan also exhibit a decreasing trend. The largest increase in moisture in Western Tianshan stems from West Asia during extreme winter precipitation months. Europe is also an important contributor to extreme precipitation in the Northern Tianshan. The moisture from East and South Asia and Siberia during extreme precipitation months in both winter and summer is significantly enhanced in the Eastern Tianshan.
    Description: Key Points: Local evaporation and Central Asia play a leading role in providing moisture for all sub‐regions of the Tianshan Mountains. The largest moisture component during the months of extreme winter precipitation for Western Tianshan derives from western Asia. Moisture from East and South Asia and Siberia during extreme precipitation months is significantly enhanced in the Eastern Tianshan.
    Description: China Scholarship Council
    Description: Humboldt‐Universität zu Berlin
    Description: https://zenodo.org/record/6451656#.YrrfbqhBwuU
    Keywords: ddc:551.6
    Language: English
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  • 108
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    Late Quaternary paleoenvironmental reconstructions from sediments of Lake Emanda (Verkhoyansk Mountains, East Siberia) (2022)
    Andreev, Andrei A. ; Nazarova, Larisa B. ; Lenz, Marlene M. ; [et al.]
    Details
    Publication Date: 2022-09-27
    Description: Continuous pollen and chironomid records from Lake Emanda (65°17′N, 135°45′E) provide new insights into the Late Quaternary environmental history of the Yana Highlands (Yakutia). Larch forest with shrubs (alders, pines, birches) dominated during the deposition of the lowermost sediments suggesting its Early Weichselian [Marine Isotope Stage (MIS) 5] age. Pollen‐ and chironomid‐based climate reconstructions suggest July temperatures (TJuly) slightly lower than modern. Gradually increasing amounts of herb pollen and cold stenotherm chironomid head capsules reflect cooler and drier environments, probably during the termination of MIS 5. TJuly dropped to 8 °C. Mostly treeless vegetation is reconstructed during MIS 3. Tundra and steppe communities dominated during MIS 2. Shrubs became common after ~14.5 ka bp but herb‐dominated habitats remained until the onset of the Holocene. Larch forests with shrub alder and dwarf birch dominated after the Holocene onset, ca. 11.7 ka bp. Decreasing amounts of shrub pollen during the Lateglacial are assigned to the Older Dryas and Younger Dryas with TJuly ~ 7.5 °C. TJuly increased up to 13 °C. Shrub stone pine was present after ~7.5 ka bp. The vegetation has been similar to modern since ca. 5.8 ka bp. Chironomid diversity and concentration in the sediments increased towards the present day, indicating the development of richer hydrobiological communities in response to the Holocene thermal maximum.
    Description: Russian Scientific Foundation
    Description: German Federal Ministry of Education and Research
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: RSF
    Description: Russian Ministry of Education and Science
    Description: Federal Ministry of Education and Research
    Description: BMBF
    Keywords: ddc:560
    Language: English
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  • 109
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    Inspecting the Reliability of Geochemical Facies Identified for the Waterworks' Capture Zone in Germany (2022)
    Blackwell Publishing Ltd | Malden, US
    Details
    Publication Date: 2022-09-27
    Description: Little research attention has been given to validating clusters obtained from the groundwater geochemistry of the waterworks' capture zone with a prevailing lake‐groundwater exchange. To address this knowledge gap, we proposed a new scheme whereby Gaussian finite mixture modeling (GFMM) and Spike‐and‐Slab Bayesian (SSB) algorithms were utilized to cluster the groundwater geochemistry while quantifying the probability of the resulting cluster membership against each other. We applied GFMM and SSB to 13 geochemical parameters collected during different sampling periods at 13 observation points across the Barnim Highlands plateau located in the northeast of Berlin, Germany; this included 10 observation wells, two lakes, and a gallery of drinking production wells. The cluster analysis of GFMM yielded nine clusters, either with a probability ≥0.8, while the SSB produced three hierarchical clusters with a probability of cluster membership varying from 〈0.2 to 〉0.8. The findings demonstrated that the clustering results of GFMM were in good agreement with the classification as per the principal component analysis and Piper diagram. By superimposing the parameter clustering onto the observation clustering, we could identify discrepancies that exist among the parameters of a certain cluster. This enables the identification of different factors that may control the geochemistry of a certain cluster, although parameters of that cluster share a strong similarity. The GFMM results have shown that from 2002, there has been active groundwater inflow from the lakes towards the capture zone. This means that it is necessary to adopt appropriate measures to reverse the inflow towards the lakes.
    Description: Article impact statement: The probability of cluster membership quantified using an algorithm should be validated against another probabilistic‐based classifier.
    Description: Federal Ministry of Education and Research http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:551.9 ; ddc:551.49
    Language: English
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  • 110
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    Stratospheric Moistening After 2000 (2022)
    Details
    Publication Date: 2022-09-27
    Description: The significant climate feedback of stratospheric water vapor (SWV) necessitates quantitative estimates of SWV budget changes. Model simulations driven by the newest European Centre for Medium‐Range Weather Forecast reanalysis ERA5, satellite observations from the Stratospheric Water and OzOne Satellite Homogenized data set, Microwave Limb Sounder, and in situ frost point hygrometer observations from Boulder all show substantial and persistent stratospheric moistening after a sharp drop in water vapor at the turn of the millennium. This moistening occurred mainly during 2000–2006 and SWV abundances then remained high over the last decade. We find strong positive trends in the Northern Hemisphere and weak negative trends over the South Pole, mainly during austral winter. Moistening of the tropical stratosphere after 2000 occurred during late boreal winter/spring, reached values of ∼0.2 ppm/decade, was well correlated with a warming of the cold point tropopause by ∼0.4 K/decade and can only be partially attributed to El Nino‐Southern Oscillation and volcanic eruptions.
    Description: Plain Language Summary: Water vapor is an effective greenhouse gas. Human‐induced climate change has led to warmer air in the troposphere, which consequently can hold more moisture, thus enhancing the greenhouse effect. The long‐term change in stratospheric water vapor (SWV) is less clear and currently under debate. Using satellite observations, balloon soundings and model simulations, we find an increase of SWV after 2000. This moistening occurred mainly during 2000–2006 and the stratospheric moisture content then remained high over the last decade. The increase of SWV is stronger in the Northern than in the Southern Hemisphere. Over the South Pole, a weak decrease was found. Moistening of the tropical stratosphere occurred mainly during late winter and spring, and was in line with warming of the tropical tropopause, the coldest region that separates the troposphere and stratosphere. Natural causes such as volcanic eruptions cannot completely explain this stratospheric moistening.
    Description: Key Points: Stratospheric moistening after 2000 is clearly detectable in ERA5‐driven simulations, satellite and in situ observations. Hemispheric asymmetry is found with strong positive trends in the Northern Hemisphere and weak negative trends over the South Pole. Moistening of the lower tropical stratosphere is only partially caused by El Nino‐Southern Oscillation and volcanic eruptions.
    Description: https://doi.org/10.5067/Aura/MLS/DATA2508
    Description: https://doi.org/10.5067/GLOSSAC-L3-V2.0
    Description: https://doi.org/10.5067/GLOSSAC-L3-V2.0
    Keywords: ddc:551.6
    Language: English
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  • 111
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    Geomagnetic Detection of the Atmospheric Acoustic Resonance at 3.8 mHz During the Hunga Tonga Eruption Event on 15 January 2022 (2022)
    Details
    Publication Date: 2022-09-29
    Description: Modeling studies have predicted that the acoustic resonance of the atmosphere during geophysical events such as earthquakes and volcanos can lead to an oscillation of the geomagnetic field with a frequency of about 4 mHz. However, observational evidence is still limited due to scarcity of suitable events. On 15 January 2022, the submarine volcano Hunga Tonga‐Hunga Ha'apai (20.5°S, 175.4°W, Tonga) erupted in the Pacific Ocean and caused severe atmospheric disturbance, providing an opportunity to investigate geomagnetic effects associated with acoustic resonance. Following the eruption, geomagnetic oscillation is observed at Apia, approximately 835 km from Hunga Tonga, mainly in the Pc 5 band (150–600 s, or 1.7–6.7 mHz) lasting for about 2 hr. The dominant frequency of the oscillation is 3.8 mHz, which is consistent with the frequency of the atmospheric oscillation due to acoustic resonance. The oscillation is most prominent in the eastward (Y) component, with an amplitude of ∼3 nT, which is much larger than those previously reported for other events (〈1 nT). Comparably large oscillation is not found at other stations located further away (〉2700 km). However, geomagnetic oscillation with a much smaller amplitude (∼0.3 nT) is observed at Honolulu, which is located near the magnetic conjugate point of Hunga Tonga, in a similar wave form as at Apia, indicating interhemispheric coupling. This is the first time that geomagnetic oscillations due to the atmospheric acoustic resonance are simultaneously detected at magnetic conjugate points.
    Description: Key Points: The effect of the January 2022 Hunga Tonga‐Hunga Ha’apai volcano eruption on the geomagnetic field is examined. Geomagnetic oscillation with a frequency of ∼3.8 mHz is observed simultaneously near the volcano and its magnetic conjugate point. The oscillation is attributed to the acoustic resonance of the atmosphere.
    Description: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior http://dx.doi.org/10.13039/501100002322
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://www.intermagnet.org/data-donnee/download-eng.php
    Keywords: ddc:538.7 ; ddc:551.5
    Language: English
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  • 112
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    Role of Poroelasticity During the Early Postseismic Deformation of the 2010 Maule Megathrust Earthquake (2022)
    Peña, Carlos ; Metzger, Sabrina ; Heidbach, Oliver ; [et al.]
    Details
    Publication Date: 2022-09-29
    Description: Megathrust earthquakes impose changes of differential stress and pore pressure in the lithosphere‐asthenosphere system that are transiently relaxed during the postseismic period primarily due to afterslip, viscoelastic and poroelastic processes. Especially during the early postseismic phase, however, the relative contribution of these processes to the observed surface deformation is unclear. To investigate this, we use geodetic data collected in the first 48 days following the 2010 Maule earthquake and a poro‐viscoelastic forward model combined with an afterslip inversion. This model approach fits the geodetic data 14% better than a pure elastic model. Particularly near the region of maximum coseismic slip, the predicted surface poroelastic uplift pattern explains well the observations. If poroelasticity is neglected, the spatial afterslip distribution is locally altered by up to ±40%. Moreover, we find that shallow crustal aftershocks mostly occur in regions of increased postseismic pore‐pressure changes, indicating that both processes might be mechanically coupled.
    Description: Plain Language Summary: Large earthquakes modify the state of stress and pore pressure in the upper crust and mantle. These changes induce stress relaxation processes and pore pressure diffusion in the postseismic phase. The two main stress relaxation processes are postseismic slip along the rupture plane of the earthquake and viscoelastic deformation in the rock volume. These processes decay with time, but can sustain over several years or decades, respectively. The other process that results in volumetric crustal deformation is poroelasticity due to pore pressure diffusion, which has not been investigated in detail. Using postseismic surface displacement data acquired by radar satellites after the 2010 Maule earthquake, we show that poroelastic deformation may considerably affect the vertical component of the observed geodetic signal during the first months. Poroelastic deformation also has an impact on the estimation of the postseismic slip, which in turn affects the energy stored at the fault plane that is available for the next event. In addition, shallow aftershocks within the continental crust show a good, positive spatial correlation with regions of increased postseismic pore‐pressure changes, suggesting they are linked. These findings are thus important to assess the potential seismic hazard of the segment.
    Description: Key Points: A poro‐viscoelastic deformation model improves the geodetic data misfit by 14% compared to an elastic model that only accounts for afterslip. Poroelastic deformation mainly produces surface uplift and landward displacement patterns on the coastal forearc region. Neglecting poroelastic effects may locally alter the afterslip amplitude by up to ±40% near the region of maximum coseismic slip.
    Description: Helmholtz Association (亥姆霍兹联合会致力) http://dx.doi.org/10.13039/501100009318
    Keywords: ddc:551
    Language: English
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  • 113
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    The detection of bacterial exometabolites in marine dissolved organic matter through ultrahigh‐resolution mass spectrometry (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-01
    Description: Bacteria play a key role in sustaining the chemodiversity of marine dissolved organic matter (DOM), yet there is limited direct evidence of a major contribution of bacterial exometabolites to the DOM pool. This study tests whether molecular formulae of intact exometabolites can be detected in natural DOM via untargeted Fourier‐transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). We analyzed a series of quantitative mixtures of solid‐phase extracted DOM from the deep ocean, of a natural microbial community and selected model strains of marine bacteria. Under standard instrument settings (200 broadband scans, mass range 92–1000 Da), 77% of molecular formulae were shared between the mesocosm and marine DOM. However, there was 〈 10% overlap between pure bacterial exometabolome with marine DOM, and in mixing ratios closest to mimicking natural environments (1% bacterial DOM, 99% marine DOM), only 4% of the unique bacterial exometabolites remained detectable. Further experiments with the bacterial exometabolome DOM mixtures using enhanced instrument settings resulted in increased detection of the exometabolites at low concentrations. At 1000 and 10,000 accumulated scans, 23% and 29% of the unique molecular formulae were detectable at low concentrations, respectively. Moreover, windowing a specific mass range encompassing a representative fraction of exometabolites tripled the number of unique detected formulae at low concentrations. Routine FT‐ICR‐MS settings are thus not always sufficient to distinguish bacterial exometabolome patterns from a seawater DOM background. To observe these patterns at higher sensitivity, we recommend a high scan number coupled with windowing a characteristic region of the molecular fingerprint.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.46 ; ddc:579.3 ; ddc:
    Language: English
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    Application of mixed‐effects modelling and rule‐based models to explain copper variation in soil profiles of southern Germany (2022)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2022-10-01
    Description: Copper (Cu) is an essential element for plants and microorganisms and at larger concentrations a toxic pollutant. A number of factors controlling Cu dynamics have been reported, but information on quantitative relationships is scarce. We aimed to (i) quantitatively describe and predict soil Cu concentrations (CuAR) in aqua regia considering site‐specific effects and effects of pH, soil organic carbon (SOC) and cation exchange capacity (CEC), and (ii) study the suitability of mixed‐effects modelling and rule‐based models for the analysis of long‐term soil monitoring data. Thirteen uncontaminated long‐term monitoring soil profiles in southern Germany were analysed. Since there was no measurable trend of increasing CuAR concentrations with time in the respective depth ranges of the sites, data from different sampling dates were combined and horizon‐specific regression analyses including model simplifications were carried out for 10 horizons. Fixed‐ and mixed‐effects models with the site as a random effect were useful for the different horizons and significant contributions (either of main effects or interactions) of SOC, CEC and pH were present for 9, 8 and 7 horizons, respectively. Horizon‐specific rule‐based cubist models described the CuAR data similarly well. Validations of cubist models and mixed‐effects models for the CuAR concentrations in A horizons were successful for the given population after random splitting into calibration and validation samples, but not after independent validations with random splitting according to sites. Overall, site, CEC, SOC and pH provide important information for a description of CuAR concentrations using the different regression approaches. Highlights: Information on quantitative relationships for factors controlling Cu dynamics is scarce. Site, CEC, SOC and pH provide important information for a description of Cu concentrations. Validations of cubist models and mixed‐effects models for A horizons were successful for a closed population of sites.
    Description: Bavarian State Ministry of the Environment and Consumer Protection http://dx.doi.org/10.13039/501100010219
    Description: Ministry of Agriculture and Environment Mecklenburg‐Western Pomerania
    Keywords: ddc:631.4
    Language: English
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    Tides, Stratification, and Counter Rotation: The German Bight ROFI in Comparison to Other Regions of Freshwater Influence (2022)
    Details
    Publication Date: 2022-10-01
    Description: The characteristics of tidal velocity profiles and their relation to stratification are investigated based on high‐resolution field data collected at four locations in the German Bight Region of Freshwater Influence (ROFI) in the North Sea. The deployments each include two to three tidal cycles and were conducted during field campaigns in August 2016 and May 2018. The depth‐averaged semidiurnal tidal motion is dominated by a standing wave directed toward the coast, but modified by a smaller, coast‐parallel progressive wave contribution. The time series of the tidal velocity profiles consistently show tidal asymmetries with higher flood than ebb velocities near the surface and counter‐clockwise rotation of the velocity trajectories at depth. Near the surface, phase‐locked periodic changes in the sense of rotation within the tidal cycle are evident for three deployments, resulting in periodic counter‐rotation of the upper and lower layer. During these episodes, stratification of the water column is observed. Counter‐rotation is initiated after a sudden decoupling developing from the surface downward, with subsequent rapid development of stratification and velocity shear. The observed decoupling is most likely triggered by advection of the plume‐induced lateral surface density gradient by weakly sheared ebb currents toward the study site. Due to the dominance of the standing wave in the German Bight ROFI, the observed intra‐tidal variations of stratification are more similar to the Liverpool Bay and differ significantly from the Rhine ROFI, where the tidal dynamics are controlled by a progressive Kelvin wave.
    Description: Plain Language Summary; The water velocities in the German Bight are strongly influenced by river freshwater input and semidiurnal tides. While the freshwater input from the rivers has a stratifying effect, tidal motion as well as wind and waves induce mixing. These forces compete in controlling the state of the water column in a complex manner. In theory, tidal motion should describe elliptical paths. However, in reality, these ellipses can be modified for example, by periodically occurring stratification. To assess the characteristics of the semidiurnal tidal velocity profile and its variability, four instruments to measure current velocity profiles were deployed in the German Bight during August 2016 and May 2018. Measurements were carried out for the duration of up to three tidal cycles, accompanied by parallel profiles of water temperature and salinity taken from the anchored ship nearby. Results show that periodic stratification related to the river freshwater plume is associated with periodically counter‐rotating tidal currents during the tidal cycle. The measurement position relative to the location of the density front of the plume appears to be critical for the occurrence of counter‐rotation. The observed dynamics are qualitatively compared to two other well‐studied coastal ocean regions of freshwater influence.
    Description: Key Points: High‐resolution velocity and density data from the German Bight Region of Freshwater Influence are used to assess M2 tidal properties and intra‐tidal variability. M2 tidal motion is a hybrid of standing and progressive waves, with the standing wave contribution dominating. Periodic counter‐rotation of upper‐ and lower‐layer current trajectories during the tidal cycle is related to water column stratification.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.1594/PANGAEA.919168
    Description: https://doi.pangaea.de/10.1594/PANGAEA.943958
    Description: https://doi.pangaea.de/10.1594/PANGAEA.943955
    Description: https://doi.org/10.1594/PANGAEA.897214
    Keywords: ddc:551.46
    Language: English
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    The Hidden Giant: How a rift pulse triggered a cascade of sector collapses and voluminous secondary mass‐transport events in the early evolution of Santorini (2022)
    Details
    Publication Date: 2022-10-01
    Description: Volcanic island sector collapses have the potential to trigger devastating tsunamis and volcanic eruptions that threaten coastal communities and infrastructure. Considered one of the most hazardous volcano‐tectonic regions in the world, the Christiana‐Santorini‐Kolumbo Volcanic Field (CSKVF) lies in the South Aegean Sea in an active rift zone. Previous studies identified an enigmatic voluminous mass‐transport deposit west and east of Santorini emplaced during the early evolution of the edifice. However, the distribution and volume as well as the nature and emplacement dynamics of this deposit remained unknown up to now. In this study, we use an extensive dataset of high‐resolution seismic profiles to unravel the distribution and internal architecture of this deposit. We show that it is located in all basins surrounding Santorini and has a bulk volume of up to 125 km3, thus representing the largest known volcanic island mass‐transport deposit in the entire Mediterranean Sea. We propose that the deposit is the result of a complex geohazard cascade that was initiated by an intensive rift pulse. This rifting event triggered a series of smaller precursory mass‐transport events before large‐scale sector collapses occurred on the northeastern flank of the extinct Christiana Volcano and on the southeastern flank of the nascent Santorini. This was followed by the emplacement of large‐scale secondary sediment failures on the slopes of Santorini, which transitioned into debris and turbidity flows that traveled far into the neighboring rift basins. Following this cascade, a distinct change in the volcanic behaviour of the CSKVF occurred, suggesting a close relationship between crustal extension, mass transport and volcanism. Cascading geohazards seem to be more common in the evolution of marine volcanic systems than previously appreciated. Wider awareness and a better understanding of cascading effects are crucial for more holistic hazard assessments.
    Description: Schematic Reconstruction of the Santorini Mass‐Transport Cascade (SMTC): After a phase of volcanic quiescence (A), a rift pulse (B) triggered precursory mass‐wasting events (C), large‐scale sector collapses (D) and secondary sediment failures (E), which culminated in a change in the volcanic behaviour of the system (F).
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.21
    Language: English
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    Analytical Artefacts Preclude Reliable Isotope Ratio Measurement of Internal Water in Coral Skeletons (2022)
    de Graaf, Stefan ; Vonhof, Hubert B. ; Reijmer, John J. G. ; [et al.]
    Details
    Publication Date: 2022-10-01
    Description: Internal water in cold‐water and tropical coral skeletons was extracted and measured for its oxygen and hydrogen isotope ratios. Water was extracted by crushing pieces of coral hard tissue in a percussion device connected to either a cavity ring‐down spectroscopy (CRDS) system or an isotope ratio mass spectrometry (IRMS) system. Despite most samples yielding sufficient water, each analytical system produces distinct isotope patterns. Experiments show that several characteristics specific to biominerals give rise to discrepancies and analytical artefacts that preclude the acquisition of reproducible isotope data. The main complication is that internal water in biogenic carbonates is distributed in an open interconnected micro‐network that readily exchanges with external water and potentially facilitates interaction with hydration water in the finely dispersed organic matrix in the coral skeleton. Furthermore, only an isotopically fractionated part of the internal water is released from the coral skeletons upon crushing. Altogether, isotope ratio measurement of internal water in corals with bulk crushing techniques does not give primary fluid isotope ratios useful for (palaeo‐)environmental or microbiological studies. As the resulting isotope patterns can show systematic behaviour per technique, isotope data may be erroneously interpreted to reflect the original calcifying fluid when using only a single technique to isotopically characterise internal fluids in coral skeletons.
    Description: Key Points: Free water trapped inside coral skeletons was extracted and isotopically analyzed on two commonly used techniques for fluid inclusion isotope analysis. Measured oxygen and hydrogen isotope ratios do not reproduce between the techniques due to several analytical artefacts. The water extracted from coral skeletons is not of primary origin.
    Description: Nederlandse Organisatie voor Wetenschappelijk Onderzoek http://dx.doi.org/10.13039/501100003246
    Description: Western Indian Ocean Marine Science Association http://dx.doi.org/10.13039/501100009106
    Keywords: ddc:551.9
    Language: English
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    Greigite (Fe3S4) Formation in Artificial Sediments via Solid‐State Transformation of Lepidocrocite (2022)
    Details
    Publication Date: 2022-09-30
    Description: Greigite (Fe3S4) is a ferrimagnetic iron‐sulfide mineral that forms in sediments during diagenesis. Greigite growth can occur diachronously within a stratigraphic profile, complicating or overprinting environmental and paleomagnetic records. An important objective for paleo‐ and rock‐magnetic studies is to identify the presence of greigite and to discern its formation conditions. Greigite detection remains, however, challenging and its magnetic properties obscure due to the lack of pure, stable material of well‐defined grain size. To overcome these limitations, we report a new method to selectively transform lepidocrocite to greigite via the intermediate phase mackinawite (FeS). In‐situ magnetic characterization was performed on discrete samples with different sediment substrates. Susceptibility and chemical remanent magnetization increased proportionally over time, defining two distinct greigite growth regimes. Temperature dependent and constant initial growth rates indicate a solid‐state FeS to greigite transformation with an activation energy of 78–90 kJ/mol. Low and room temperature magnetic remanence and coercivity ratios match with calculated mixing curves for superparamagnetic (SP) and single domain (SD) greigite and suggest ∼25% and ∼50% SD proportions at 300 and 100 K, respectively. The mixing trend coincides with empirical data reported for natural greigite‐bearing sediments, suggesting a common SP endmember size of 5–10 nm that is likely inherited from mackinawite crystallites. The average particle size of 20–50 nm determined by X‐ray powder diffraction and electron microscopy accords with theoretical predictions of the SP/SD threshold size in greigite. The method constitutes a novel approach to synthesize greigite and to investigate its formation in sediments.
    Description: Plain Language Summary: Sediments provide continuous records of Earth's ancient magnetic field, which lend insights into the workings of the geodynamo and help to establish the geologic time scale through global magnetostratigraphic correlation. Greigite is a magnetic iron sulfide mineral that commonly forms after deposition, thereby remagnetizing the sediment and complicating interpretation of the magnetic record. Understanding greigite formation and detecting its presence is fundamental for obtaining reliable records of the paleomagnetic field, yet knowledge of how greigite grows and how its magnetic properties evolve during growth remains limited. This article outlines a novel approach to form greigite in sediments and to monitor its growth kinetics, grain size and magnetic remanence acquisition. The magnetic properties of the synthetic sediments resemble those of natural greigite‐bearing sediments and match well with theoretical calculations, which can help quantify grain sizes in sedimentary greigite. The reported method and our results contribute to a better understanding of greigite formation and chemical magnetic remanence acquisition in sediments.
    Description: Key Points: We present a new method to grow greigite in aqueous sediments and create a chemical remanent magnetization under controlled conditions. Greigite grain sizes of 20–50 nm span the superparamagnetic to single domain threshold, consistent with theoretical predictions. Our experimental hysteresis data coincide with calculated mixing curves allowing better quantification of greigite particle sizes in nature.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6521653
    Keywords: ddc:549
    Language: English
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    A New Population of Ultra‐Relativistic Electrons in the Outer Radiation Zone (2022)
    Details
    Publication Date: 2022-09-30
    Description: Van Allen Probes measurements revealed the presence of the most unusual structures in the ultra‐relativistic radiation belts. Detailed modeling, analysis of pitch angle distributions, analysis of the difference between relativistic and ultra‐realistic electron evolution, along with theoretical studies of the scattering and wave growth, all indicate that electromagnetic ion cyclotron (EMIC) waves can produce a very efficient loss of the ultra‐relativistic electrons in the heart of the radiation belts. Moreover, a detailed analysis of the profiles of phase space densities provides direct evidence for localized loss by EMIC waves. The evolution of multi‐MeV fluxes shows dramatic and very sudden enhancements of electrons for selected storms. Analysis of phase space density profiles reveals that growing peaks at different values of the first invariant are formed at approximately the same radial distance from the Earth and show the sequential formation of the peaks from lower to higher energies, indicating that local energy diffusion is the dominant source of the acceleration from MeV to multi‐MeV energies. Further simultaneous analysis of the background density and ultra‐relativistic electron fluxes shows that the acceleration to multi‐MeV energies only occurs when plasma density is significantly depleted outside of the plasmasphere, which is consistent with the modeling of acceleration due to chorus waves.
    Description: Plain Language Summary: The most energetic electrons in the Earth Van Allen radiation belts have not been accurately measured in the past. Observations for a recent NASA's Van Allen Probes missions reviled new unique structures, such as narrow rings, and posed further scientific questions. This review shows that, unlike relativistic electrons, ultra‐relativistic electrons can be very effectively locally scattered by plasma waves produced by ions, so‐called electromagnetic ion cyclotron waves. Observations also show that acceleration from MeV to multi‐MeV occurs locally by taking energy from another type of plasma wave. These waves are called whistler‐mode waves and can accelerate particles to such high energy when total plasma density is low. The difference between the relativistic and ultra‐relativistic particles justifies the classification of these particles into a different population from the bulk population of the outer radiation belt.
    Description: Key Points: Electromagnetic ion cyclotron waves effectively scatter ultra‐relativistic electrons in the radiation belts. The local acceleration produces acceleration from MeV to multi‐MeV in the regions of low density. The difference between MeV and multi‐MeV electrons justifies the classification of these particles into a new population.
    Description: EC, H2020, H2020 Priority Excellent Science, H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: NASA
    Description: https://rbspgway.jhuapl.edu/
    Keywords: ddc:538.7
    Language: English
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    Asteroid 2008 TC3, not a polymict ureilitic but a polymict C1 chondrite parent body? Survey of 249 Almahata Sitta fragments (2022)
    Details
    Publication Date: 2022-09-30
    Description: On October 7, 2008, the asteroid 2008 TC3 exploded as it entered the Earth’s atmosphere, producing significant dust (in the atmosphere) and delivering thousands of stones in a strewn field in Sudan, collectively known as the Almahata Sitta (AhS) stones. About 600 fragments were officially recovered in 2008 and 2009. Further rocks were collected since the fall event by local people. From these stones, 249 were classified at the Institut für Planetologie in Münster (MS) known as MS‐xxx or MS‐MU‐xxx AhS subsamples. Most of these rocks are ureilitic in origin (168; 67%): 87 coarse‐grained ureilites, 60 fine‐grained ureilites, 15 ureilites with variable texture/mineralogy, four trachyandesites, and two polymict breccias. We identified 81 non‐ureilitic fragments, corresponding to 33% of the recovered samples studied in Münster. These included chondrites, namely 65 enstatite chondrites (43 EL; 22 EH), 11 ordinary chondrites (OC), one carbonaceous chondrite, and one unique R‐like chondrite. Furthermore, three samples represent a unique type of enstatite achondrite. Since all AhS stones must be regarded as individual specimens independent from each other, the number of fresh ureilite and enstatite chondrite falls in our meteorite collections has been increased by several hundred percent. Overall, the samples weigh between 〈1 and 250 g and have a mean mass of ~15 g. If we consider—almost 15 years after the fall—the mass calculations, observations during and after the asteroid entered the atmosphere, the mineralogy of the C1 stones AhS 91A and AhS 671, and the experimental work on fitting the asteroid spectrum (e.g., Goodrich et al., 2019; Jenniskens et al., 2010; Shaddad et al., 2010), the main portion of the meteoroid was likely made of the fine‐grained (carbonaceous) dust and was mostly lost in the atmosphere. In particular, the fact that C1 materials were found has important implications for interpreting asteroid 2008 TC3's early spectroscopic results. Goodrich et al. (2019) correctly suggested that if scientists had not recovered the “water‐free” samples (e.g., ureilites, enstatites, and OC) from the AhS strewn field, 2008 TC3 would have been assumed to be a carbonaceous chondrite meteoroid. Considering that the dominating mass of the exploding meteoroid consisted of carbonaceous materials, asteroid 2008 TC3 cannot be classified as a polymict ureilite; consequently, we state that the asteroid was a polymict carbonaceous chondrite breccia, specifically a polymict C1 object that may have formed by late accretion at least 50–100 Ma after calcium–aluminum‐rich inclusions.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Alexander von Humboldt Foundation http://dx.doi.org/10.13039/100005156
    Keywords: ddc:549.112 ; ddc:523
    Language: English
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    Algorithmic Differentiation for Sensitivity Analysis in Cloud Microphysics (2022)
    Details
    Publication Date: 2022-10-04
    Description: The role of clouds for radiative transfer, precipitation formation, and their interaction with atmospheric dynamics depends strongly on cloud microphysics. The parameterization of cloud microphysical processes in weather and climate models is a well‐known source of uncertainties. Hence, robust quantification of this uncertainty is mandatory. Sensitivity analysis to date has typically investigated only a few model parameters. We propose algorithmic differentiation (AD) as a tool to detect the magnitude and timing at which a model state variable is sensitive to any of the hundreds of uncertain model parameters in the cloud microphysics parameterization. AD increases the computational cost by roughly a third in our simulations. We explore this methodology as the example of warm conveyor belt trajectories, that is, air parcels rising rapidly from the planetary boundary layer to the upper troposphere in the vicinity of an extratropical cyclone. Based on the information of derivatives with respect to the uncertain parameters, the ten parameters contributing most to uncertainty are selected. These uncertain parameters are mostly related to the representation of hydrometeor diameter and fall velocity, the activation of cloud condensation nuclei, and heterogeneous freezing. We demonstrate the meaningfulness of the AD‐estimated sensitivities by comparing the AD results with ensemble simulations spawned at different points along the trajectories, where different parameter settings are used in the various ensemble members. The ranking of the most important parameters from these ensemble simulations is consistent with the results from AD. Thus, AD is a helpful tool for selecting parameters contributing most to cloud microphysics uncertainty.
    Description: Plain Language Summary: The formation of clouds is determined by processes that act on smaller scales than weather prediction models can resolve. Consequently, a parameterization with typically hundreds of parameters is constructed to determine the effects of these processes on the resolved larger scales. These parameters are a well‐known source of uncertainty in weather and climate models. Classical attempts to quantify this uncertainty are typically limited to a few parameters. We propose algorithmic differentiation (AD) as a tool to detect parameters with the largest impact for any of the hundreds of parameters on multiple model state variables at every time step in our simulation. This increases the computational cost by roughly a third. The relevance of the AD‐estimated impact is demonstrated by comparing the AD results with ensemble simulations, where different parameter settings are used in the various ensemble members. The ranking of the most important parameters from these ensemble simulations is consistent with the results from AD. Thus, AD is a helpful tool to identify parameters objectively that contribute most to uncertainty in cloud parameterizations.
    Description: Key Points: Quantification of multi‐parameter uncertainty of cloud microphysical evolution of WCB trajectories using algorithmic differentiation. Uncertainty at every time step derived with algorithmic differentiation representative for key uncertainty over at least 30 min intervals. Parameterization of CCN activation, diameter size, and fall velocity of hydrometeors have the largest mean impact on water vapor contents.
    Description: Deutsch Forschungsgemeinschaft DFG
    Keywords: ddc:551.5
    Language: English
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    Representation of hydrological processes in a rural lowland catchment in Northern Germany using SWAT and SWAT+ (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-04
    Description: The latest version of the Soil and Water Assessment Tool (SWAT+) features several improvements compared with previous versions of the model, for example, the definition of landscape units that allow for a better representation of spatio‐temporal dynamics. To evaluate the new model capabilities in lowland catchments characterized by near‐surface groundwater tables and extensive tile drainage, we assess the performance of two SWAT+ model setups in comparison to a setup based on a previous SWAT model version (SWAT3S with a modified three groundwater storage model) in the Kielstau catchment in Northern Germany. The Kielstau catchment has an area of about 50 km2, is dominated by agricultural land use, and has been thoroughly monitored since 2005. In both SWAT+ setups, the catchment is divided into upland areas and floodplains, but in the first SWAT+ model setup, runoff from the hydrologic response units is summed up at landscape unit level and added directly to the stream. In the second SWAT+ model setup, runoff is routed across the landscape before it reaches the streams. Model results are compared with regard to (i) model performance for stream flow at the outlet of the catchment and (ii) aggregated as well as temporally and spatially distributed water balance components. All three model setups show a very good performance at the catchment outlet. In comparison to a previous version of the SWAT model that produced more groundwater flow, the SWAT+ model produced more tile drainage flow and surface runoff. Results from the new SWAT+ model confirm that the representation of routing processes from uplands to floodplains in the model further improved the representation of hydrological processes. Particularly, the stronger spatial heterogeneity that can be related to characteristics of the landscape, is very promising for a better understanding and model representation of hydrological fluxes in lowland areas. The outcomes of this study are expected to further prove the applicability of SWAT+ and provide useful information for future model development.
    Description: The model performance of all three model setups was very good, but the SWAT+ model setup with runoff routing between landscape units performed best. Moreover, the SWAT+ model applications predicted a greater spatial heterogeneity of the water balance components. The representation of hydrological fluxes particularly with regard to groundwater flow, surface runoff, and tile drainage flow differed considerably between the SWAT and SWAT+ model setups.
    Keywords: ddc:551.48
    Language: English
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    Air‐Sea Interactions and Water Mass Transformation During a Katabatic Storm in the Irminger Sea (2022)
    Details
    Publication Date: 2022-10-04
    Description: We use a global 5‐km resolution model to analyze the air‐sea interactions during a katabatic storm in the Irminger Sea originating from the Ammassalik valleys. Katabatic storms have not yet been resolved in global climate models, raising the question of whether and how they modify water masses in the Irminger Sea. Our results show that dense water forms along the boundary current and on the shelf during the katabatic storm due to the heat loss caused by the high wind speeds and the strong temperature contrast. The dense water contributes to the lightest upper North Atlantic Deep Water as upper Irminger Sea Intermediate Water and thus to the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). The katabatic storm triggers a polar low, which in turn amplifies the near‐surface wind speed due to the superimposed pressure gradient, in addition to acceleration from a breaking mountain wave. Overall, katabatic storms account for up to 25% of the total heat loss (20 January 2020 to 30 September 2021) over the Irminger shelf of the Ammassalik area. Resolving katabatic storms in global models is therefore important for the formation of dense water in the western boundary current of the Irminger Sea, which is relevant to the AMOC, and for the large‐scale atmospheric circulation by triggering polar lows.
    Description: Plain Language Summary: Katabatic storms are outbursts of cold air associated with strong winds from coastal valleys of Greenland, in particular from the Ammassalik valleys in southeast Greenland. These storms are not resolved in global climate models because of their small spatial extent. However, they are important for the formation of dense water on the Irminger Sea shelf, because they induce a substantial heat loss from the coastal water. In this study, we resolve katabatic storms for the first time in a global climate model and analyze the water transformation caused by a single storm before quantifying the importance of katabatic storms for the entire simulation period. We find that a water mass is formed during the katabatic storm that is dense enough to contribute to the cooling and sinking of the global conveyor belt in the subpolar North Atlantic. Overall, katabatic storms account for up to 25% of the heat loss over the Irminger shelf of the Ammassalik area.
    Description: Key Points: For the first time, the direct effect of a katabatic storm on the Irminger Sea has been simulated in a global climate model. The katabatic storm induces strong heat loss and dense water formation over the Irminger shelf (Sermilik Trough) and in the boundary current. Dense water forming in the western boundary current during katabatic storms contributes to the lightest upper North Atlantic Deep Water.
    Description: Collaborative Research Centre TRR181 funded by DFG
    Description: Max Planck Society for Advancement of Science
    Description: NextGEMS
    Description: European Union’s Horizon 2020
    Description: https://hdl.handle.net/21.11116/0000-0008-ECF1-E
    Description: https://cera-www.dkrz.de/WDCC/ui/Compact.jsp?acronym=DKRZ_LTA_033_ds00010
    Description: https://mpimet.mpg.de/en/science/modeling-with-icon/code-availability
    Keywords: ddc:551.5
    Language: English
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    Robust approaches for model‐free small‐angle scattering data analysis (2022)
    Bender, Philipp ; Honecker, Dirk ; Bersweiler, Mathias ; [et al.]
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2022-10-04
    Description: The small‐angle neutron scattering data of nanostructured magnetic samples contain information regarding their chemical and magnetic properties. Often, the first step to access characteristic magnetic and structural length scales is a model‐free investigation. However, due to measurement uncertainties and a restricted q range, a direct Fourier transform usually fails and results in ambiguous distributions. To circumvent these problems, different methods have been introduced to derive regularized, more stable correlation functions, with the indirect Fourier transform being the most prominent approach. Here, the indirect Fourier transform is compared with the singular value decomposition and an iterative algorithm. These approaches are used to determine the correlation function from magnetic small‐angle neutron scattering data of a powder sample of iron oxide nanoparticles; it is shown that with all three methods, in principle, the same correlation function can be derived. Each method has certain advantages and disadvantages, and thus the recommendation is to combine these three approaches to obtain robust results.
    Description: Three different approaches are compared for determination of the correlation function from the small‐angle neutron scattering data of a powder sample of iron oxide nanoparticles.
    Keywords: ddc:548
    Language: English
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    Temporal evolution of headwall erosion rates derived from cosmogenic nuclide concentrations in the medial moraines of Glacier d'Otemma, Switzerland (2022)
    Details
    Publication Date: 2022-10-04
    Description: Climate change affects the stability and erosion of high‐alpine rock walls above glaciers (headwalls) that deliver debris to glacier surfaces. Since supraglacial debris in the ablation zone alters the melt behaviour of the underlying ice, the responses of debris‐covered glaciers and of headwalls to climate change may be coupled. In this study, we analyse the beryllium‐10 (10Be)‐cosmogenic nuclide concentration history of glacial headwalls delivering debris to the Glacier d'Otemma in Switzerland. By systematic downglacier‐profile‐sampling of two parallel medial moraines, we assess changes in headwall erosion through time for small, well‐defined debris source areas. We compute apparent headwall erosion rates from 10Be concentrations ([10Be]), measured in 15 amalgamated medial moraine debris samples. To estimate both the additional 10Be production during glacial debris transport and the age of our samples we combine our field‐based data with a simple model that simulates downglacier debris trajectories. Furthermore, we evaluate additional grain size fractions for eight samples to test for stochastic mass wasting effects on [10Be]. Our results indicate that [10Be] along the medial moraines vary systematically with time and consistently for different grain sizes. [10Be] are higher for older debris, closer to the glacier terminus, and lower for younger debris, closer to the glacier head. Computed apparent headwall erosion rates vary between ~0.6 and 10.8 mm yr−1, increasing over a maximum time span of ~200 years towards the present. As ice cover retreats, newly exposed headwall surfaces may become susceptible to enhanced weathering and erosion, expand to lower elevations, and contribute formerly shielded bedrock of likely different [10Be]. Hence, we suggest that recently lower [10Be] reflect the deglaciation of the debris source areas since the end of the Little Ice Age.
    Description: In glacial landscapes, systematic downglacier‐sampling of medial moraine debris holds the potential to assess changes in headwall erosion through time. Cosmogenic beryllium‐10 (10Be) concentrations within the medial moraines of Glacier d'Otemma, Switzerland, broadly increase downglacier and translate into increasing headwall erosion rates towards the present. These trends may reflect processes associated with the exposure of new bedrock surfaces across recently deglaciating source headwalls.
    Description: European Research Council (ERC) H2020‐EU.1.1.
    Description: https://doi.org/10.5880/GFZ.3.3.2021.007
    Keywords: ddc:551
    Language: English
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    Palaeoecological signals for Mesolithic land use in a Central European landscape? (2022)
    Heidgen, Shaddai ; Marinova, Elena ; Nelle, Oliver ; [et al.]
    Details
    Publication Date: 2022-10-04
    Description: During the Early Holocene, climate was the major factor causing fires, but whether during the Mesolithic (~11.5–7.4 cal ka BP) people co‐shaped their environment by means of fire remains of debate. Few studies have tackled this question by linking high‐resolution multi‐proxy palaeoecological studies from near Mesolithic occupation sites. An Early Holocene sediment record from the Ammer Valley palaeo‐wetland in south‐west Germany was studied using pollen, micro‐ and macrocharcoal, and plant macroremains. Archaeological evidence from Early and Late Mesolithic sites of Rottenburg‐Siebenlinden allowed us to link this palaeoecological record with Mesolithic land use in the same catchment. Between 11.6 and 10.6 cal kabp,intensive wildfires reinforced the persistence of open and pioneer vegetation. A transition from a river‐dominated landscape towards a wetland with open stagnant waters at 10.6–9.5 cal ka bpmade the region attractive to hunter‐gatherers, providing various plant resources (incl. hazel). From 10.1 cal ka bponwards, Mesolithic communities may have shaped their environment by using fire as a tool to expand open areas, which were important for the implementation of their subsistence strategies. After 9.5 cal ka bp, human control over fires cannot be excluded as Mesolithic occupation phases chronologically coincide with frequent low‐intensity fires and vegetation disturbance.
    Keywords: ddc:561
    Language: English
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    Benthic Carbon Remineralization and Iron Cycling in Relation to Sea Ice Cover Along the Eastern Continental Shelf of the Antarctic Peninsula (2022)
    Details
    Publication Date: 2022-10-04
    Description: Rapid and profound climatic and environmental changes have been predicted for the Antarctic Peninsula with so far unknown impact on the biogeochemistry of the continental shelves. In this study, we investigate benthic carbon sedimentation, remineralization and iron cycling using sediment cores retrieved on a 400 mile transect with contrasting sea ice conditions along the eastern shelf of the Antarctic Peninsula. Sediments at comparable water depths of 330–450 m showed sedimentation and remineralization rates of organic carbon, ranging from 2.5 to 13 and 1.8–7.2 mmol C m−2 d−1, respectively. Both rates were positively correlated with the occurrence of marginal sea ice conditions (5%–35% ice cover) along the transect, suggesting a favorable influence of the corresponding light regime and water column stratification on algae growth and sedimentation rates. From south to north, the burial efficiency of organic carbon decreased from 58% to 27%, while bottom water temperatures increased from −1.9 to −0.1°C. Net iron reduction rates, as estimated from pore‐water profiles of dissolved iron, were significantly correlated with carbon degradation rates and contributed 0.7%–1.2% to the total organic carbon remineralization. Tightly coupled phosphate‐iron recycling was indicated by significant covariation of dissolved iron and phosphate concentrations, which almost consistently exhibited P/Fe flux ratios of 0.26. Iron efflux into bottom waters of 0.6–4.5 μmol Fe m−2 d−1 was estimated from an empirical model. Despite the deep shelf waters, a clear bentho‐pelagic coupling is indicated, shaped by the extent and duration of marginal sea ice conditions during summer, and likely to be affected by future climate change.
    Description: Plain Language Summary: The seafloor of the shallow shelf seas plays a significant role in the recycling of organic carbon and acts as a nutrient source for algae growth in the upper water layers. In Antarctic waters, the change in sea ice cover has a great impact on the growth of algae and the subsequent sinking of organic carbon to the seafloor. With global warming, profound changes in sea ice cover are expected for the Antarctic Peninsula. To better understand its imprint on the seafloor, we collected sediment samples from different locations along the eastern shelf of the Antarctic Peninsula and measured how changes in sea ice cover influence the accumulation and recycling of organic carbon. We found that moderate sea ice cover of 5%–35% increases the amount of organic carbon received by the seafloor and that the fraction that is buried in the sediments decreases from south (58%) to north (27%). We further measured that more iron, an important micro‐nutrient for algae growth, can be released from the seafloor the more organic carbon accumulates. Thus, sea ice conditions determine the organic carbon accumulation, turnover, and nutrient release at the seafloor, which are likely to be affected by future climate change.
    Description: Key Points: Antarctic shelf sediments underlying marginal sea ice cover exhibit high sedimentation and remineralization rates of organic carbon. A high degree of sedimentary Fe‐recycling is found which scales with organic carbon remineralization rates. Coupling between P and Fe recycling is observed with a constant P/Fe flux ratio of 0.26 for sediments with high Fe and P recycling rates.
    Description: Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research http://dx.doi.org/10.13039/501100003207
    Description: https://doi.org/10.1594/PANGAEA.942455
    Keywords: ddc:551.9
    Language: English
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    Sound Velocity Measurements of B2‐Fe‐Ni‐Si Alloy Under High Pressure by Inelastic X‐Ray Scattering: Implications for the Composition of Earth's Core (2022)
    Details
    Publication Date: 2022-10-04
    Description: Elastic properties of B2‐Fe0.67Ni0.06Si0.27 (15 wt.% Si) alloy have been investigated by combined high‐resolution inelastic X‐ray scattering and powder X‐ray diffraction in diamond anvil cells up to 100 GPa at room temperature. Densities (ρ), compressional (VP) and shear (VS) wave velocities were extrapolated to inner core conditions to enable comparison with the preliminary reference Earth model. The modeled aggregate compressional and shear wave velocities and densities of the two‐phase mixture of B2‐Fe0.67Ni0.06Si0.27 and hcp‐Fe‐Ni are consistent with inner core PREM values of VP, VS, and ρ based on a linear mixing model with 30(5) vol % B2‐Fe0.67Ni0.06Si0.27 and 70(5) vol % hcp Fe‐Ni, which corresponds to ∼3–5 wt.% Si and ∼5–12 wt.% Ni.
    Description: Plain Language Summary: The composition of the inner core holds key information about how Earth evolved and how current processes such as the geomagnetic field work. Because the core cannot be directly sampled, our best estimates of its composition are based on the comparison of geophysical data with laboratory measurements of candidate materials. Decades of study have shown the inner core to be composed mainly of iron (with a minor amount of nickel) alloyed with one or more light elements, such as silicon. However, the effect of Si on the geophysical properties of Fe‐Ni alloys is not well established. In this study, we performed laboratory experiments to determine the density and sound velocity of Fe‐Ni‐Si alloy under extreme pressure conditions. We compared our results with seismological determinations and found that Earth's inner core can be accounted for by a mechanical mixture of cubic Fe‐Ni‐Si and hexagonal Fe‐Ni alloys. This mixture has a bulk composition of ∼3–5 weight % Si and ∼5–12 weight % Ni and is consistent with geophysical constraints.
    Description: Key Points: Sound velocities and densities of B2‐Fe‐Ni‐Si alloy are determined at high pressure, up to 100 GPa, using inelastic X‐ray scattering and X‐ray diffraction. Seismologically observed compressional and shear wave velocities and density of Earth's inner core can be accounted for by a two‐phase mixture of 30 vol % B2‐Fe‐Ni‐Si and 70 vol % hcp Fe‐Ni alloys. Extrapolated results at inner core boundary conditions are consistent with an inner core composition containing ∼3–5 wt.% Si and ∼5–12 wt.% Ni.
    Description: Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: JSPS Japanese‐German graduate externship
    Description: https://doi.org/10.6084/m9.figshare.13370795.v1
    Description: https://doi.org/10.6084/m9.figshare.13370792.v1
    Keywords: ddc:551.112
    Language: English
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    Spatio‐Temporal Level Variations of the Martian Seasonal South Polar Cap From Co‐Registration of MOLA Profiles (2022)
    Details
    Publication Date: 2022-10-04
    Description: The seasonal deposition and sublimation of CO2 represents a major element in the Martian volatile cycle. Here, co‐registration strategies are applied to Mars Orbiter Laser Altimeter profiles to obtain spatio‐temporal variations in snow/ice level of the Seasonal South Polar Cap (SSPC), in grid elements of 0.5° in latitude from 60° to 87°S and 10° in longitude. The maximum snow/ice level in the range of 2–2.5 m is observed over the Residual South Polar Cap. Peak level at the Residual South Polar Cap in Martian Year 25 (MY25) are found to be typically ∼0.5 m higher than those in MY24. The total volume is estimated to peak at approximately 9.4 × 1012 m3. In addition, a map of average bulk density of the SSPC during its recession is derived. It implies much more snowfall‐like precipitation at the Residual South Polar Cap and its surroundings than elsewhere on Mars.
    Description: Plain Language Summary: Each Martian year, up to one third of the atmosphere's CO2 is transported from pole to pole, being deposited and sublimated depending on the season. Accurate measurements of snow level and volume variations of the resulting seasonal polar caps can serve as crucial constraints on the Martian volatile cycles. In this study, we apply new approaches of analyzing the Mars Orbiter Laser Altimeter profiles, which lead to spatially and temporally resolved measurements of snow/ice level of the Seasonal South Polar Cap (SSPC). Based on that, the maximum snow level, interannual maximum level change from Martian Year 24 (MY24) to MY25, and how the volume of the SSPC changes with time are measured. We also estimate the bulk density of the snow/ice deposition during southern winter. It is inferred that there is much more snowfall at the Residual South Polar Cap and its surroundings than elsewhere on the planet.
    Description: Key Points: Using co‐registration of Mars Orbiter Laser Altimeter profiles, spatio‐temporal level variations of the seasonal snow/ice deposits at the Martian south pole are obtained. Maximum level can be up to 2.5 m; Peak level increased by ∼0.5 m at the Residual South Polar Cap from Martian Year 24 (MY24) to MY25. Obtained bulk density map of the seasonal deposits implies that snowfall concentrates at the Residual South Polar Cap and its surroundings.
    Description: China Scholarship Council
    Description: Deutsche Forschungsgemeinschaft
    Description: Institut National des Sciences de l’Univers
    Description: Centre National de la Recherche Scientifique
    Description: Centre National d’Etudes Spatiales
    Description: https://pds-geosciences.wustl.edu/missions/mgs/pedr.html
    Description: https://naif.jpl.nasa.gov/pub/naif/pds/data/mgs-m-spice-6-v1.0/mgsp_1000/data/
    Description: https://doi.org/10.17632/z59b9nd6s9.2
    Description: https://doi.org/10.14768/8cba4407-d6a0-4d16-aeaf-d0ebfd2b480a
    Keywords: ddc:523
    Language: English
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    Greenhouse Gas Mitigation Potential of Alternate Wetting and Drying for Rice Production at National Scale—A Modeling Case Study for the Philippines (2022)
    Kraus, David ; Werner, Christian ; Janz, Baldur ; [et al.]
    Details
    Publication Date: 2022-10-04
    Description: Worldwide, rice production contributes about 10% of total greenhouse gas (GHG) emissions from the agricultural sector, mainly due to CH4 emissions from continuously flooded fields. Alternate Wetting and Drying (AWD) is a promising crop technology for mitigating CH4 emissions and reducing the irrigation water currently being applied in many of the world's top rice‐producing countries. However, decreased emissions of CH4 may be partially counterbalanced by increased N2O emissions. In this case study for the Philippines, the national mitigation potential of AWD is explored using the process‐based biogeochemical model LandscapeDNDC. Simulated mean annual CH4 emissions under conventional rice production for the time period 2000–2011 are estimated as 1,180 ± 163 Gg CH4 yr−1. During the cropping season, this is about +16% higher than a former estimate using emission factors. Scenario simulations of nationwide introduction of AWD in irrigated landscapes suggest a considerable decrease in CH4 emissions by −23%, while N2O emissions are only increased by +8%. Irrespective of field management, at national scale, the radiative forcing of irrigated rice production is always dominated by CH4 (〉95%). The reduction potential of GHG emissions depends on, for example, number of crops per year, residue management, amount of applied irrigation water, and sand content. Seasonal weather conditions also play an important role since the mitigation potential of AWD is almost double as high in dry as compared to wet seasons. Furthermore, this study demonstrates the importance of temporal continuity, considering off‐season emissions and the long‐term development of GHG emissions across multiple years.
    Description: Plain Language Summary: Worldwide, rice production contributes to about 10% of total greenhouse gas emissions of the agricultural sector mainly due to CH4 emissions from fields that are continuously flooded. Alternate Wetting and Drying (AWD) is an alternative cropping practice where fields are irrigated a few days after the disappearance of the ponded water. This study explores the mitigation potential of nationwide introduction of AWD in the Philippines. Results from the application of a process‐based model suggest a considerable decrease in CH4 emissions by −23%. Compared to N2O, CH4 is responsible for more than 95% of the total radiative forcing under conventional or AWD field management.
    Description: Key Points: Nationwide, Alternate Wetting and Drying (AWD) reduces CH4 emissions by −23%. N2O emissions contribute to less than 5% to the total radiative forcing under conventional or AWD field management. Mitigation of AWD depends on, for example, seasonal weather conditions, cropping intensity, irrigation, residue management, and soil texture.
    Description: DFG
    Description: https://doi.org/10.35097/588
    Keywords: ddc:551.6 ; ddc:581.7
    Language: English
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    Simultaneously tracing the fate of seven metals at a global level with MaTrace‐multi (2022)
    Details
    Publication Date: 2022-10-04
    Description: Keeping materials in use for a long time is key to reducing primary material demand and environmental impacts of resource use. Recycling yields of metals should only be limited by thermodynamically unavoidable losses of the remelting processes for well‐defined scraps. In practice, however, additional dissipative losses for metals occur due to incomplete collection of end‐of‐life products, insufficient waste sorting, remelting of contaminated or diluted scrap, and the downcycling of secondary materials. Here we simultaneously trace the fate of Al, Cr, Fe, Ni, Cu, Zn, and Pb in MaTrace‐multi, a planetary dynamic material flow system. Metals pass the processes mining, fabrication, use‐phase, collection, sorting, scrap allocation, remelting, and secondary material allocation. We calculate the circularity and longevity of the cohort of metal requirements for the final demand of 1 year. Nickel is found to have the best longevity at 116 (78 to 205) years, whereas zinc only has a longevity of 47 (37 to 61) years. While nickel, on average, is used in 5.13 (3.45 to 8.78) applications before dissipation, zinc is used only in 1.94 (1.52 to 2.47) applications. Our study results can be used to model the impacts of circular economy policies and technological developments on global metal cycles beyond the scope of studies modeling one metal at a time. This article met the requirements for a Gold–Gold JIE data openness badge described at http://jie.click/badges
    Description: https://doi.org/10.17605/OSF.IO/R54C6
    Keywords: ddc:363.7282
    Language: English
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    Flexible habitat choice of pelagic bacteria increases system stability and energy flow through the microbial loop (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-04
    Description: Pelagic bacteria can be classified into free‐living and particle‐attached life modes, which either dwell in the water column or attach to suspended particles. Bacteria with a generalist life style, however, can actively shift between these two habitats. Globally increasing densities of natural and artificial particles enhance habitat heterogeneity, with potential consequences for system stability and trophic transfer through aquatic food webs. To better decipher the dynamics of microbial communities, we investigated the influence of adaptive vs. fixed habitat choice on species coexistence for a simplified bacterial community by analyzing a corresponding food web model, consisting of two specialist bacterial prey species (free and attached), a generalist bacterial prey species with the ability to shift between both habitats, and two protist predators, specialized on either water or particle compartment. For simplicity we assume a shared resource pool, considering particles only for colonization but not as a source for nutrients or carbon, that is, inert particles like microplastics or inorganic sediments. The model predicts coexistence on a cyclic attractor between fixed and flexible bacteria, if the costs for adaptive habitat choice can be balanced by adaptation speed. The presence of adaptive prey dampens predator–prey cycle amplitudes, contributing to system stabilization resulting in higher mean predator biomass compared to specialist prey only. Thus, in pelagic microbial systems, flexible habitat choice at the prey level has important implications for system stability and magnitude of energy flow through the microbial loop.
    Description: German Ministry of Education and Science
    Description: German Science Foundation (DFG)
    Keywords: ddc:579.3
    Language: English
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    Basin‐scale estimates of greenhouse gas emissions from the Mara River, Kenya: Importance of discharge, stream size, and land use/land cover (2022)
    Mwanake, Ricky M. ; Gettel, Gretchen M. ; Ishimwe, Clarisse ; [et al.]
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-04
    Description: Greenhouse gas fluxes (CO2, CH4, and N2O) from African streams and rivers are under‐represented in global datasets, resulting in uncertainties in their contributions to regional and global budgets. We conducted year‐long sampling of 59 sites in a nested‐catchment design in the Mara River, Kenya in which fluxes were quantified and their underlying controls assessed. We estimated annual basin‐scale greenhouse gas emissions from measured in‐stream gas concentrations, modeled gas transfer velocities, and determined the sensitivity of up‐scaling to discharge. Based on the total annual CO2‐equivalent emissions calculated from global warming potentials (GWP), the Mara basin was a net greenhouse gas source (294 ± 35 Gg CO2 eq yr−1). Lower‐order streams (1–3) contributed 81% of the total fluxes, and higher stream orders (4–8) contributed 19%. Cropland‐draining streams also exhibited higher fluxes compared to forested streams. Seasonality in stream discharge affected stream widths (and stream area) and gas exchange rates, strongly influencing the basin‐wide annual flux, which was 10 times higher during the high and medium discharge periods than the low discharge period. The basin‐wide estimate was underestimated by up to 36% if discharge was ignored, and up to 37% for lower stream orders. Future research should therefore include seasonality in stream surface areas in upscaling procedures to better constrain basin‐wide fluxes. Given that agricultural activities are a major factor increasing riverine greenhouse gas fluxes in the study region, increased conversion of forests and agricultural intensification has the possibility of increasing the contribution of the African continent to global greenhouse gas sources.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: IHE Delft Institute for Water Education
    Description: Federal Ministry of Education and Research http://dx.doi.org/10.13039/501100002347
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: TERENO Bavarian Alps/ Pre‐Alps Observatory
    Keywords: ddc:551
    Language: English
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    Deepening the Late Quaternary's Deep Ocean Carbon Mysteries (2022)
    Details
    Publication Date: 2022-10-04
    Description: Changes to the carbon content of the deep ocean, the largest reservoir in the surficial carbon cycle, are capable of altering atmospheric carbon dioxide concentrations and thereby Earth's climate. While the role of the deep ocean's carbon inventory in the last ice age has been thoroughly investigated, comparatively little is known about whether the deep ocean contributed to the change in the pacing and intensity of ice ages around 1 million years ago during the Mid‐Pleistocene Transition (MPT). Qin et al. (2022, https://doi.org/10.1029/2021GL097121) provide new reconstructions of deep ocean carbonate ion saturation, a proxy for carbon content, from the deep Pacific Ocean across the MPT. Intriguingly, their results show that a reduction in deep Pacific carbonate ion saturation across the MPT occurred at different intervals from carbonate ion saturation decline in the deep Atlantic Ocean. These results suggest a more nuanced contribution of whole‐ocean carbon sequestration to the climate changes reconstructed across the MPT.
    Description: Plain Language Summary: Earth's periodic ice ages became longer and more intense around 1 million years ago. While the underlying reasons for this climate change remain debated, it is widely understood that the deep ocean may have played an important role by storing the potent greenhouse gas carbon dioxide away from the atmosphere. New research by Qin et al. (2022, https://doi.org/10.1029/2021gl097121) shows that the deep Pacific Ocean did indeed accumulate additional carbon around the time of this million‐year old climate transition. However, the new results also show that Pacific Ocean accumulated carbon over different intervals than the Atlantic Ocean, deepening the mystery around how and why this carbon uptake occurred.
    Description: Key Points: The deep Atlantic and Pacific Oceans accumulated carbon at different intervals during the mid‐Pleistocene transition.
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.1029/2021GL097121
    Keywords: ddc:551
    Language: English
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    Effective buoyancy and CAPE: Some implications for tropical cyclones (2022)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2022-10-04
    Description: We review the widely used concepts of “buoyancy” and “convective available potential energy” (CAPE) in relation to deep convection in tropical cyclones and discuss their limitations. A fact easily forgotten in applying these concepts is that the buoyancy force of an air parcel, as often defined, is non‐unique because it depends on the arbitrary definition of a reference density field. However, when calculating CAPE, the buoyancy of a lifted air parcel is related to the specific reference density field along a vertical column passing through that parcel. Both concepts can be generalized for a vortical flow and to slantwise ascent of a lifted air parcel in such a flow. In all cases, the air parcel is assumed to have infinitely small dimensions. In this article, we explore the consequences of generalizing buoyancy and CAPE for buoyant regions of finite size that perturb the pressure field in their immediate environment. Quantitative calculations of effective buoyancy, defined as the sum of the conventional buoyancy and the static vertical perturbation pressure gradient force induced by it, are shown for buoyant regions of finite width. For a judicious choice of reference density, the effective buoyancy per unit mass is essentially a unique force, independent of the reference density, but its distribution depends on the horizontal scale of the buoyant region. A corresponding concept of “effective CAPE” is introduced and its relevance to deep convection in tropical cyclones is discussed. The study is conceived as a first step to understanding the decreasing ability of inner‐core deep convection in tropical cyclones to ventilate the mass of air converging in the frictional boundary layer as the vortex matures and decays.
    Description: The buoyancy force of an infinitesimally small air parcel is non‐unique, depending on the arbitrary definition of a reference density field. When calculating the “convective available potential energy” (CAPE), the buoyancy of a lifted air parcel is related to the reference density field along a vertical column passing through that parcel. We generalize buoyancy and CAPE for buoyant regions of finite size that perturb the pressure field in their immediate environment and discuss the relevance to deep convection in tropical cyclones.
    Keywords: ddc:551.5
    Language: English
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    Performance of a Rotational Sensor to Decipher Volcano Seismic Signals on Etna, Italy (2022)
    Eibl, Eva P. S. ; Rosskopf, Martina ; Sciotto, Mariangela ; [et al.]
    Details
    Publication Date: 2022-10-04
    Description: Volcano‐seismic signals such as long‐period events and tremor are important indicators for volcanic activity and unrest. However, their wavefield is complex and characterization and location using traditional seismological instrumentation is often difficult. In 2019 we recorded the full seismic wavefield using a newly developed 3C rotational sensor co‐located with a 3C traditional seismometer on Etna, Italy. We compare the performance of the rotational sensor, the seismometer and the Istituto Nazionale di Geofisica e Vulcanologia‐Osservatorio Etneo (INGV‐OE) seismic network with respect to the analysis of complex volcano‐seismic signals. We create event catalogs for volcano‐tectonic (VT) and long‐period (LP) events combining a STA/LTA algorithm and cross‐correlations. The event detection based on the rotational sensor is as reliable as the seismometer‐based detection. The LP events are dominated by SH‐type waves. Derived SH phase velocities range from 500 to 1,000 m/s for LP events and 300–400 m/s for volcanic tremor. SH‐waves compose the tremor during weak volcanic activity and SH‐ and SV‐waves during sustained strombolian activity. We derive back azimuths using (a) horizontal rotational components and (b) vertical rotation rate and transverse acceleration. The estimated back azimuths are consistent with the INGV‐OE event location for (a) VT events with an epicentral distance larger than 3 km and some closer events, (b) LP events and tremor in the main crater area. Measuring the full wavefield we can reliably analyze the back azimuths, phase velocities and wavefield composition for VT, LP events and tremor in regions that are difficult to access such as volcanoes.
    Description: Plain Language Summary: Traditional seismographs usually include mass and spring systems which measure vibrations constrained to up‐down, north‐south and east‐west directions. We compare the traditional seismometer to a rotational sensor which measures ground rotation around the same three directions. We installed a rotational sensor on Etna volcano in 2019 to test these new sensors in a volcanic environment. We compare the performance of the rotational sensor, a traditional seismometer and the Istituto Nazionale di Geofisica e Vulcanologia‐Osservatorio Etneo (INGV‐OE) seismometer network. We detect two types of a few second long earthquakes and find that the rotational sensor performs as good as the seismometer. We use the rotational sensor to calculate directions of the earthquake locations and find that most directions agree with the INGV‐OE network location and the area of the active craters. We find that for some earthquakes the ground only moved horizontally while for others it also moved up and down. Using a rotational sensor on a volcano we can easily and reliably estimate the ground motion, the speed of the earthquake waves in the ground and understand better how these earthquakes are generated.
    Description: Key Points: We tested the performance of a rotational sensor compared to a seismometer and a seismic network using long‐period (LP), volcano‐tectonic (VT) events and tremor on Etna. LP and VT events are dominated by SH‐ and SV‐waves, respectively. Tremor changed from SH‐ to a mixed wavefield during strombolian eruptions. LP event and tremor back azimuths point to the main craters consistent with the Istituto Nazionale di Geofisica e Vulcanologia location; VT event back azimuths are at times consistent.
    Description: Eurovolc
    Description: Daimler Benz Foundation
    Description: https://doi.org/10.14470/ME7564062119
    Keywords: ddc:551.2
    Language: English
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    New impact diagnostics for cross‐validation of different observation types (2022)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2022-10-04
    Description: New cross‐validation diagnostics have been derived by further partitioning well‐established impact diagnostics. They are related to consistency relations, the most prominent of which indicates whether the first‐guess departures of a given observation type pull the model state into the direction of the verifying data (when processed with the ensemble estimated model error covariances). Alternatively, this can be regarded as cross‐validation between model error covariance estimates from the ensemble (which are used in the data assimilation system) and estimates diagnosed directly from the observations. A statistical cross‐validation tool has been developed that includes an indicator of statistical significance as well as a normalization that makes the statistical comparison largely independent from the total number of data and the closeness of their collocation. We also present a version of these diagnostics related to single‐observation experiments that exploits the same consistency relations but is easier to compute. Diagnostics computed within the Deutscher Wetterdienst's localized ensemble transform Kalman filter (LETKF) are presented for various kinds of bins. Results from well‐established in‐situ measurements are taken as a benchmark for more complex observations. Good agreement is found for radio‐occultation bending angle measurements, whereas atmospheric motion vectors are generally also beneficial but substantially less optimal than the corresponding in‐situ measurements. This is consistent with reported atmospheric motion vector height assignment problems. To illustrate its potential, a recent example is given where the method allowed identifying bias problems of a subgroup of aircraft measurements. Another diagnostic relationship compares the information content of the analysis increments with a theoretical optimum. From this, the information content of the LETKF increments is found to be considerably lower than those of the deterministic hybrid ensemble–variational system, which is consistent with the LETKF's limitation to the comparably low‐dimensional ensemble space for finding the optimal analysis.
    Description: New cross‐validation diagnostics are presented, allowing to test the consistent use of different observation types in the data assimilation system. The figure gives an example in which these new diagnostics allowed identification of the detrimental impact of a group of aircraft measurements (which as a consequence has now been blacklisted in the Deutscher Wetterdienst's operational system). More precisely, brown colors in this plot indicate regions where these aircraft measurements pulled the analysis state away from radiosonde observations.
    Keywords: ddc:551.5
    Language: English
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    Millimetre scale aeration of the rhizosphere and drilosphere (2022)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2022-10-04
    Description: Soil aeration is a critical factor for oxygen‐limited subsoil processes, as transport by diffusion and advection is restricted by the long distance to the free atmosphere. Oxygen transport into the soil matrix is highly dependent on its connectivity to larger pore channels like earthworm and root colonised biopores. Here we hypothesize that the soil matrix around biopores represents different connectivity depending on biopore genesis and actual coloniser. We analysed the soil pore system of undisturbed soil core samples around biopores generated or colonised by roots and earthworms and compared them with the pore system of soil, not in the immediacy of a biopore. Oxygen partial pressure profiles and gas relative diffusion was measured in the rhizosphere and drilosphere from the biopore wall into the bulk soil with microelectrodes. The measurements were linked with structural features such as porosity and connectivity obtained from X‐ray tomography and image analysis. Aeration was enhanced in the soil matrix surrounding biopores in comparison to the bulk soil, shown by higher oxygen concentrations and higher relative diffusion coefficients. Biopores colonised by roots presented more connected lateral pores than earthworm colonised ones, which resulted in enhanced aeration of the rhizosphere compared to the drilosphere. This has influenced biotic processes (microbial turnover/mineralization or root respiration) at biopore interfaces and highlights the importance of microstructural features for soil processes and their dependency on the biopore's coloniser.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4
    Language: English
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    Variability in the Concentration of Lithium in the Indo‐Pacific Ocean (2022)
    Details
    Publication Date: 2022-10-04
    Description: Lithium has limited biological activity and can readily replace aluminium, magnesium and iron ions in aluminosilicates, making it a proxy for the inorganic silicate cycle and its potential link to the carbon cycle. Data from the North Pacific Ocean, tropical Indian Ocean, Southern Ocean and Red Sea suggest that salinity normalized dissolved lithium concentrations vary by up to 2%–3% in the Indo‐Pacific Ocean. The highest lithium concentrations were measured in surface waters of remote North Pacific and Indian Ocean stations that receive relatively high fluxes of dust. The lowest dissolved lithium concentrations were measured just below the surface mixed layer of the stations with highest surface water concentrations, consistent with removal into freshly forming aluminium rich phases and manganese oxides. In the North Pacific, water from depths 〉2,000 m is slightly depleted in lithium compared to the initial composition of Antarctic Bottom Water, likely due to uptake of lithium by authigenically forming aluminosilicates. The results of this study suggest that the residence time of lithium in the ocean may be significantly shorter than calculated from riverine and hydrothermal fluxes.
    Description: Key Points: Li/Na ratios vary by up to 2%–3% in the Indian and Pacific Oceans. Authigenic formation of aluminosilicates slightly deplete deep‐water lithium concentrations in the North Pacific. The residence time of lithium in the ocean is 240,000 ± 70,000 years, based on removal from North Pacific deep‐water.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: MoES, Indian National Centre for Ocean Information Services http://dx.doi.org/10.13039/501100004814
    Description: National Science Foundation USA
    Description: https://doi.pangaea.de/10.1594/PANGAEA.941888
    Keywords: ddc:551
    Language: English
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    Reassessing evidence of Moon–Earth dynamics from tidal bundles at 3.2 Ga (Moodies Group, Barberton Greenstone Belt, South Africa) (2022)
    Details
    Publication Date: 2022-10-04
    Description: Past orbital parameters of the Moon are difficult to reconstruct from geological records because relevant data sets of tidal strata are scarce or incomplete. The sole Archean data point is from the Moodies Group (ca 3.22 Ga) of the Barberton Greenstone Belt, South Africa. From the time‐series analysis of tidal bundles from a well‐exposed subaqueous sand wave of this unit, Eriksson and Simpson (Geology, 28, 831) suggested that the Moon’s anomalistic month at 3.2 Ga was closer to 20 days than the present 27.5 days. This is in apparent accordance with models of orbital mechanics which place the Archean Moon in a closer orbit with a shorter period, resulting in stronger tidal action. Although this study’s detailed geological mapping and section measuring of the site confirmed that the sandstone bed in question is likely a migrating dune, the presence of angular mud clasts, channel‐margin slumps, laterally aggrading channel fills and bidirectional paleocurrents in overlying and underlying beds suggests that this bedform was likely located in a nearshore channel near lower‐intertidal flats and subtidal estuarine bars; it thus carries risk of incomplete preservation. Repeated measurements of foreset thicknesses along the published traverse, measured perpendicular to bedding, failed to show consistent spectral peaks. Larger data sets acquired along traverses measured parallel to bedding along the 20.5 m wide exposure are affected by minor faulting, uneven outcrop weathering, changing illumination, weather, observer bias and show a low reproducibility. The most robust measurements herein confirm the periodicity peak of approximately 14 in the original data of Eriksson and Simpson (Geology, 28, 831). Because laminae may have been eroded, the measurements may represent a lower bound of about 28 lunar days per synodic month. This estimate agrees well with Earth–Moon dynamic models which consider the conservation of angular momentum and place the Archaean Moon in a lower orbit around a faster‐spinning Earth.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.3 ; ddc:556
    Language: English
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    Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait (2022)
    Details
    Publication Date: 2022-10-04
    Description: The Arctic Ocean is considered a source of micronutrients to the Nordic Seas and the North Atlantic Ocean through the gateway of Fram Strait (FS). However, there is a paucity of trace element data from across the Arctic Ocean gateways, and so it remains unclear how Arctic and North Atlantic exchange shapes micronutrient availability in the two ocean basins. In 2015 and 2016, GEOTRACES cruises sampled the Barents Sea Opening (GN04, 2015) and FS (GN05, 2016) for dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn). Together with the most recent synopsis of Arctic‐Atlantic volume fluxes, the observed trace element distributions suggest that FS is the most important gateway for Arctic‐Atlantic dissolved micronutrient exchange as a consequence of Intermediate and Deep Water transport. Combining fluxes from FS and the Barents Sea Opening with estimates for Davis Strait (GN02, 2015) suggests an annual net southward flux of 2.7 ± 2.4 Gg·a−1 dFe, 0.3 ± 0.3 Gg·a−1 dCo, 15.0 ± 12.5 Gg·a−1 dNi and 14.2 ± 6.9 Gg·a−1 dCu from the Arctic toward the North Atlantic Ocean. Arctic‐Atlantic exchange of dMn and dZn were more balanced, with a net southbound flux of 2.8 ± 4.7 Gg·a−1 dMn and a net northbound flux of 3.0 ± 7.3 Gg·a−1 dZn. Our results suggest that ongoing changes to shelf inputs and sea ice dynamics in the Arctic, especially in Siberian shelf regions, affect micronutrient availability in FS and the high latitude North Atlantic Ocean.
    Description: Plain Language Summary: Recent studies have proposed that the Arctic Ocean is a source of micronutrients such as dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn) to the North Atlantic Ocean. However, data at the Arctic Ocean gateways including Fram Strait and the Barents Sea Opening have been missing to date and so the extent of Arctic micronutrient transport toward the Atlantic Ocean remains unquantified. Here, we show that Fram Strait is the most important gateway for Arctic‐Atlantic micronutrient exchange which is a result of deep water transport at depths 〉500 m. Combined with a flux estimate for Davis Strait, this study suggests that the Arctic Ocean is a net source of dFe, dNi and dCu, and possibly also dCo, toward the North Atlantic Ocean. Arctic‐Atlantic dMn and dZn exchange seems more balanced. Properties in the East Greenland Current showed substantial similarities to observations in the upstream Central Arctic Ocean, indicating that Fram Strait may export micronutrients from Siberian riverine discharge and shelf sediments 〉3,000 km away. Increasing Arctic river discharge, permafrost thaw and coastal erosion, all consequences of ongoing climate change, may therefore alter future Arctic Ocean micronutrient transport to the North Atlantic Ocean.
    Description: Key Points: Fram Strait is the major gateway for Arctic‐Atlantic exchange of the dissolved micronutrients Fe, Mn, Co, Ni, Cu and Zn. The Arctic is a net source of dissolved Fe, Co, Ni and Cu to the Nordic Seas and toward the North Atlantic; Mn and Zn exchange are balanced. Waters of the Central Arctic Ocean, including the Transpolar Drift, are the main drivers of gross Arctic micronutrient export.
    Description: German Research Foundation
    Description: Netherlands Organization for Scientific Research
    Description: https://doi.pangaea.de/10.1594/PANGAEA.859558
    Description: https://doi.pangaea.de/10.1594/PANGAEA.871030
    Description: https://doi.pangaea.de/10.1594/PANGAEA.868396
    Description: https://doi.pangaea.de/10.1594/PANGAEA.905347
    Description: https://dataportal.nioz.nl/doi/10.25850/nioz/7b.b.jc
    Description: https://doi.pangaea.de/10.1594/PANGAEA.933431
    Description: https://www.bco-dmo.org/dataset/718440
    Description: https://doi.org/10.1594/PANGAEA.936029
    Description: https://doi.org/10.1594/PANGAEA.936027
    Description: https://doi.pangaea.de/10.1594/PANGAEA.927429
    Keywords: ddc:551.9
    Language: English
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    Contrasting State‐Dependent Effects of Natural Forcing on Global and Local Climate Variability (2022)
    Details
    Publication Date: 2022-10-04
    Description: Natural forcing from solar and volcanic activity contributes significantly to climate variability. The post‐eruption cooling of strong volcanic eruptions was hypothesized to have led to millennial‐scale variability during Glacials. Cooling induced by volcanic eruption is potentially weaker in the warmer climate. The underlying question is whether the climatic response to natural forcing is state‐dependent. Here, we quantify the response to natural forcing under Last Glacial and Pre‐Industrial conditions in an ensemble of climate model simulations. We evaluate internal and forced variability on annual to multicentennial scales. The global temperature response reveals no state dependency. Small local differences result mainly from state‐dependent sea ice changes. Variability in forced simulations matches paleoclimate reconstructions significantly better than in unforced scenarios. Considering natural forcing is therefore important for model‐data comparison and future projections.
    Description: Plain Language Summary: Climate variability describes the spatial and temporal variations of Earth's climate. Understanding these variations is important for estimating the occurrence of extreme climate events such as droughts. Yet, it is unclear whether climate variability depends on the mean surface temperature of the Earth or not. Here, we investigate the effects of natural forcing from volcanic eruptions and solar activity changes on climate variability. We compare simulations of a past (cold) and present (warm) climate with and without volcanism and solar changes. We find that overall, the climate system responds similarly to natural forcing in the cold and warm state. Small local differences mainly occur where ice can form. To evaluate the simulated variability, we use data from paleoclimate archives, including trees, ice‐cores, and marine sediments. Climate variability from forced simulations agrees better with the temperature variability obtained from data. Natural forcing is therefore critical for reliable simulation of variability in past and future climates.
    Description: Key Points: We present Glacial/Interglacial climate simulations and quantify effects of time‐varying volcanic and solar forcing on climate variability. The mean global and local response to these forcings is similar in Glacial and Interglacial climate, suggesting low state dependency. In both climate states, modeled temperature variance agrees better with palaeoclimate data when volcanic and solar forcing is included.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Heinrich Böll Stiftung (Heinrich Böll Foundation) http://dx.doi.org/10.13039/100009379
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.5281/zenodo.6074747
    Description: https://github.com/paleovar/StateDependency
    Description: https://doi.org/10.5281/zenodo.6474769
    Keywords: ddc:551.6
    Language: English
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    Climates of democracy: Skeptical, rational, and radical imaginaries (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-05
    Description: How will the theories and practices of democracy fare in a climate changing world? Are conventional democratic institutions ultimately doomed or are they able to become more responsive to a changing climate? Is there a need to reimagine democracy and how might it be reimagined? This article reviews the different responses to these questions by distinguishing between three “political imaginaries” in which the relationship between climate change and democracy takes distinct forms. I start by showing how the concept of “political imaginaries” can facilitate the comparison of the different ways in which the relation between democracy and climate change is constructed, before reviewing three such imaginaries. The skeptical imaginary, found in the “eco‐authoritarianism” of the 1970s that is echoed by much sociopolitical analysis today, casts doubt on the possibilities of democratic mechanisms to respond adequately and swiftly to the problem of climate change. Those who resist such skepticism often defend democracy by arguing that institutions and processes of democracy can be made more “ecologically rational”—the rational imaginary of climate democracy involves improvements in political representation and participation. Finally, I present the alternative radical democratic imaginary, in which the crisis of climate change provides a moment for the rupture of existing sociopolitical structures and the formation of alternatives. The article concludes that although none of these imaginaries is able to capture the entirety of climate change politics around the world, the radical democratic imaginary is responsive to the inevitable and valuable plurality around the issue of climate change. This article is categorized under: Climate, Nature, and Ethics 〉 Ethics and Climate Change Policy and Governance 〉 Multilevel and Transnational Climate Change Governance
    Description: Climate protests may mobilise new political subjects.
    Keywords: ddc:363.70561
    Language: English
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    Spatial Markov Model for the Prediction of Travel‐Time‐Based Solute Dispersion in Three‐Dimensional Heterogeneous Media (2022)
    Details
    Publication Date: 2022-10-05
    Description: In recent years, Spatial Markov Models have gained popularity in simulating solute transport in heterogeneous formations. They describe the transition times of particles between equidistant observation planes by statistical distributions, assuming correlation of the transit times of individual particles between subsequent steps. By this, the approach naturally captures preasymptotic solute dispersion. In this study, we analyze Spatial Markov Models assuming bivariate log‐normal distributions of the particle slowness (i.e., the inverse velocity) in subsequent transitions. The model is fully parameterized by the mean Eulerian velocity, the variance of the log‐slowness, and the correlation coefficient of log‐slowness in subsequent steps. We derive closed‐form expressions for distance‐dependent ensemble dispersion, which is defined in terms of the second‐central moments of the solute breakthrough curves. We relate the coefficients to the properties of the underlying log‐hydraulic conductivity field assuming second‐order stationarity. The results are consistent with linear stochastic theory in the limit of small log‐conductivity variances, while the approach naturally extends to high‐variance cases. We demonstrate the validity of the approach by comparison to three‐dimensional particle‐tracking simulations of advective transport in heterogeneous media with isotropic, exponential correlation structure for log‐conductivity variances up to five. This study contributes to relating solute dispersion to metrics of the porous‐medium structure in cases of strong heterogeneity.
    Description: Key Points: We derive closed‐form expressions of ensemble dispersion in the spatial‐Markov framework of solute transport. The expressions are consistent with linear theory in the limit of small log‐conductivity variances, but extend to high‐variance cases. Comparison to particle‐tracking simulations of advective transport in 3‐D heterogeneous domains show excellent agreement.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6554308
    Description: https://www.hsl.rl.ac.uk/catalogue/hsl_mi20.html
    Keywords: ddc:550
    Language: English
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    MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems (2022)
    Details
    Publication Date: 2022-10-05
    Description: Prediction of stable mineral equilibria in the Earth's lithosphere is critical to unravel the tectonomagmatic history of exposed geological sections. While the recent advances in geodynamic modeling allow us to explore the dynamics of magmatic transfer in solid mediums, there is to date no available thermodynamic package that can easily be linked and efficiently be accounted for the computation of phase equilibrium in magmatic systems. Moreover, none of the existing tools fully exploit single point calculation parallelization, which strongly hinders their applicability for direct geodynamic coupling or for thermodynamic database inversions. Here, we present a new Mineral Assemblage Gibbs Energy Minimizer (magemin). The package is written as a parallel C library, provides a direct Julia interface, and is callable from any petrological/geodynamic tool. For a given set of pressure, temperature, and bulk‐rock composition magemin uses a combination of linear programming, extended Partitioning Gibbs Energy and gradient‐based local minimization to compute the stable mineral assemblage. We apply our new minimization package to the igneous thermodynamic data set of Holland et al. (2018), https://doi.org/10.1093/petrology/egy048 and produce several phase diagrams at supra‐solidus conditions. The phase diagrams are then directly benchmarked against thermocalc and exhibit very good agreement. The high scalability of magemin on parallel computing facilities opens new horizons, for example, for modeling reactive magma flow, for thermodynamic data set inversion, and for petrological/geophysical applications.
    Description: Plain Language Summary: Understanding magmatic systems requires knowing how rocks melt. Because a single melting experiment can easily take weeks, it is impossible to do enough experiments to cover the whole range of pressure, temperature, and composition relevant for magmatic systems. We therefore need a way to interpolate in between conditions that are not directly covered by the experiments. It is long known that the best way to perform such interpolation is by using basic thermodynamic principles. For magmatic systems, this requires a well‐calibrated thermodynamic melting model. It also requires an efficient computational tool to predict the most stable configuration of minerals and melt. Since the 1980s, a number of such computational tools have been developed to perform a so‐called Gibbs energy minimization. These tools work very well for simpler systems but become very slow for recently developed, more realistic, melting models. Here, we describe a new method that combines some ideas of the previous methods with a new algorithm. Our method is faster and takes advantage of modern computer architectures. It can predict rock properties such as densities, seismic velocities, melt content, and chemistry. It can therefore be used to link physical observations with hard rock data of magmatic systems.
    Description: Key Points: A new, parallel, Gibbs energy minimization approach is presented to compute multiphase multicomponent equilibria. It predicts parameters like stable phases, melt content, or seismic velocities as a function of chemistry and temperature/pressure conditions. Examples and benchmark cases are presented that apply the approach to magmatic systems.
    Description: EC | H2020 | H2020 Priority Excellent Science | H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Description: https://doi.org/10.5281/zenodo.6347567
    Description: https://github.com/ComputationalThermodynamics/magemin.git
    Keywords: ddc:552
    Language: English
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    Holocene variability in sea‐ice conditions in the eastern Baffin Bay‐Labrador Sea – A north–south biomarker transect study (2022)
    Saini, Jeetendra ; Stein, Ruediger ; Fahl, Kirsten ; [et al.]
    Details
    Publication Date: 2022-10-05
    Description: Reconstructions of sea‐surface conditions during the Holocene were achieved using three sediment cores from northeastern Baffin Bay (GeoB19948‐3 and GeoB19927‐3) and the Labrador Sea (GeoB19905‐1) along a north–south transect based on sea‐ice IP25 and open‐water phytoplankton biomarkers (brassicasterol, dinosterol and HBI III). In Baffin Bay, sea‐surface conditions in the Early Holocene were characterized by extended (early) spring sea ice cover (SIC) prior to 7.6 ka BP. The conditions in the NE Labrador Sea, however, remained predominantly ice‐free in spring/autumn due to the enhanced influx of Atlantic Water (West Greenland Current, WGC) from 11.5 until ~9.1 ka BP, succeeded by a period of continued (spring–autumn) ice‐free conditions between 9.1 and 7.6 ka BP corresponding to the onset of Holocene Thermal Maximum (HTM)‐like conditions. A transition towards reoccurring ice‐edge and significantly reduced SIC conditions in Baffin Bay is evident in the Middle Holocene (~7.6–3 ka BP) probably caused by the variations in the WGC influence associated with the ice melting and can be characterized as HTM‐like conditions. These HTM‐like conditions are predominantly recorded in the NE Labrador Sea area shown by (spring–autumn) ice‐free conditions from 5.9–3 ka BP. In the Late Holocene (last ~3 ka), our combined proxy records from eastern Baffin Bay indicate low in‐situ ice algae production; however, enhanced multi‐year (drifted) sea ice in this area was possibly attributed to the increased influx of Polar Water mass influx and may correlate with the Neoglacial cooling. The conditions in the NE Labrador Sea during the last 3 ka, however, continued to remain (spring–autumn) ice‐free. Our data from the Baffin Bay–Labrador Sea transect suggest a dominant influence of meltwater influx on sea‐ice formation throughout the Holocene, in contrast to sea‐ice records from the Fram Strait area, which seem to follow predominantly the summer insolation trend.
    Description: image
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.46
    Language: English
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    Multiple Angle Observations Would Benefit Visible Band Remote Sensing Using Night Lights (2022)
    Details
    Publication Date: 2022-10-05
    Description: The spatial and angular emission patterns of artificial and natural light emitted, scattered, and reflected from the Earth at night are far more complex than those for scattered and reflected solar radiation during daytime. In this commentary, we use examples to show that there is additional information contained in the angular distribution of emitted light. We argue that this information could be used to improve existing remote sensing retrievals based on night lights, and in some cases could make entirely new remote sensing analyses possible. This work will be challenging, so we hope this article will encourage researchers and funding agencies to pursue further study of how multi‐angle views can be analyzed or acquired.
    Description: Plain Language Summary: When satellites take images of Earth, they usually do so from directly above (or as close to it as is reasonably possible). In this comment, we show that for studies that use imagery of Earth at night, it may be beneficial to take several images of the same area at different angles within a short period of time. For example, different types of lights shine in different directions (street lights usually shine down, while video advertisements shine sideways), and tall buildings can block the view of a street from some viewing angles. Additionally, since views from different directions pass through different amounts of air, imagery at multiple angles could be used to obtain information about Earth's atmosphere, and measure artificial and natural night sky brightness. The main point of the paper is to encourage researchers, funding agencies, and space agencies to think about what new possibilities could be achieved in the future with views of night lights at different angles.
    Description: Key Points: Remote sensing using the visible band at night is more complex than during the daytime, especially due to the variety of artificial lights. Views of night lights intentionally taken from multiple angles provide several advantages over near‐nadir or circumstantial view geometries. Night lights remote sensing would benefit from greater consideration of the role viewing geometry plays in the observed radiance.
    Description: EC H2020 H2020 Societal Challenges http://dx.doi.org/10.13039/100010676
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Slovak Research and Development Agency
    Description: Xunta de Galicia (Regional Government of Galicia) http://dx.doi.org/10.13039/501100010801
    Description: National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
    Description: University of Hong Kong http://dx.doi.org/10.13039/501100003803
    Description: Fonds de recherche du Québec
    Description: EC Emprego, Assuntos Sociais e Inclusão European Social Fund http://dx.doi.org/10.13039/501100004895
    Description: Natural Environment Research Council http://dx.doi.org/10.13039/501100000270
    Description: City of Cologne, Germany
    Keywords: ddc:551.5
    Language: English
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    The relationship between precipitation and its spatial pattern in the trades observed during EUREC4A (2022)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2022-10-06
    Description: Trade wind convection organises into a rich spectrum of spatial patterns, often in conjunction with precipitation development. Which role spatial organisation plays for precipitation and vice versa is not well understood. We analyse scenes of trade‐wind convection scanned by the C‐band radar Poldirad during the EUREC4A field campaign to investigate how trade‐wind precipitation fields are spatially organised, quantified by the cells' number, mean size, and spatial arrangement, and how this matters for precipitation characteristics. We find that the mean rain rate (i.e., the amount of precipitation in a scene) and the intensity of precipitation (mean conditional rain rate) relate differently to the spatial pattern of precipitation. Whereas the amount of precipitation increases with mean cell size or number, as it scales well with the precipitation fraction, the intensity increases predominantly with mean cell size. In dry scenes, the increase of precipitation intensity with mean cell size is stronger than in moist scenes. Dry scenes usually contain fewer cells with a higher degree of clustering than moist scenes do. High precipitation intensities hence typically occur in dry scenes with rather large, few, and strongly clustered cells, whereas high precipitation amounts typically occur in moist scenes with rather large, numerous, and weakly clustered cells. As cell size influences both the intensity and amount of precipitation, its importance is highlighted. Our analyses suggest that the cells' spatial arrangement, correlating mainly weakly with precipitation characteristics, is of second‐order importance for precipitation across all regimes, but it could be important for high precipitation intensities and to maintain precipitation amounts in dry environments.
    Description: We analyse scenes of trade‐wind convection scanned by the C‐band radar Poldirad during the EUREC4A field campaign to investigate how trade‐wind precipitation fields are spatially organised, quantified by the cells' number, mean size, and spatial arrangement, and how this matters for precipitation characteristics. We conclude that the cells' size is important for both the amount and intensity of precipitation, whereas the cells' spatial arrangement is of second‐order importance for precipitation across all regimes, but possibly important for precipitation in dry environments.
    Description: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy—EXC 2037 'CLICCS—Climate, Climatic Change, and Society'
    Description: https://doi.org/10.25326/217
    Description: https://doi.org/10.25326/79
    Keywords: ddc:551.5
    Language: English
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    High groundwater levels: Processes, consequences, and management (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-10-06
    Description: In recent years, the issue of high groundwater levels has caught attention. Unfavorable consequences of high groundwater levels are especially damage to buildings, infrastructure, and the environment. Processes that lead to high groundwater levels are hydrological (heavy or extended rainfall and flood events), or anthropogenic (reduced groundwater extractions, interaction with sewer networks, hydraulic engineering measures, structural interventions in the water balance, and mining activities). Several different map products have been prepared for the information of inhabitants and for planning purposes, and also methods for damage and risk analysis related to high groundwater levels have been developed. Groundwater management measures and structural measures are available to reduce the risk related to high groundwater levels. An operational management system could be combined from existing components, but operational forecasting systems for high groundwater levels are—different to flood forecasting systems—not yet common practice. A better understanding of the processes and the development of integrated approaches for modeling, design, planning, forecasting, and warning, as well as improvement of interdisciplinary collaboration between different organizations, are recommendations for the future. This article is categorized under: Engineering Water 〉 Engineering Water Water and Life 〉 Conservation, Management, and Awareness Science of Water 〉 Hydrological Processes Science of Water 〉 Water Extremes
    Description: Pumping water from a basement during the Neiße flood 2010 in Saxony. The clear water indicates that the basement flooding originates from groundwater (photo: Reinhard Schinke).
    Keywords: ddc:551.49
    Language: English
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    Capturing complex star dune dynamics—repeated highly accurate surveys combining multitemporal 3D topographic measurements and local wind data (2022)
    Details
    Publication Date: 2022-10-06
    Description: Morphologies of highly complex star dunes are the result of aeolian dynamics in past and present times. These dynamics reflect climatic conditions and associated forces like sediment availability and vegetation cover, as well as feedbacks with adjacent environments. However, an understanding of aeolian dynamics on star dune morphometries is still lacking sufficient detail, and their influence on formation and evolution remains unclear. We therefore investigate the dynamics of a complex star dune (Erg Chebbi, Morocco) by analysing wind measurements compared to morphometric changes derived from multitemporal high‐accuracy 3D observations during two surveys (October 2018 and February 2020). Using real‐time kinematic global navigation satellite system (RTK‐GNSS) measurements and terrestrial laser scanning (TLS), the reaction of a star dune surface to an observed constant unimodal sand‐moving wind is presented. TLS point clouds are used for morphometric analysis as well as direct surface change analysis, which relates to sand transport. RTK‐GNSS measurements enable the assessment of horizontal crest movement. Observed surface changes lead to the identification of an overall shielding effect, resulting in sand accumulation mainly on windward slopes. Our results point to a self‐sustained dune growth, which has not yet been described in such spatial detail. Steep slopes, often found on star dunes around the globe, seem to partly hinder upslope sand transport. Though a comparatively short observation period, we therefore hypothesize that, besides wind intensity alone, slope angles are more decisive for sand transport than previously assumed. Our methodological approach of combining meteorological data and high‐resolution multitemporal 3D elevation models can be used for monitoring all dune forms and contributes to a general understanding of dune dynamics and evolution.
    Description: The accurate detection of altitudinal surface changes on a star dune compared to climatic data enables the identification of aeolian dynamics and new mechanisms where, besides wind intensity alone, slope angles are more decisive for sand transport than previously assumed. The methodological approach can be transferred to all dune forms, ranging from small barchans to complex and extensive star dunes.
    Description: https://doi.org/10.11588/data/ZAMGCL
    Keywords: ddc:551.37
    Language: English
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    The first belemnite of boreal ancestry from the Early Cretaceous (Valanginian) of the western Tethys: implications for belemnite ecology (2022)
    Details
    Publication Date: 2022-10-06
    Description: The first occurrence of the belemnite species Liobelus acrei (formerly Acroteuthis acrei) is reported from the Lower Cretaceous (Valanginian) of the Vocontian Basin (VB; south‐east France). This first record of the genus Liobelus (Family Cylindroteuthididae), which is commonly attributed to the latest Jurassic and Early Cretaceous of the Boreal Realm, revises the spatial distribution pattern of boreal belemnites significantly. The Valanginian belemnite assemblages of the VB are dominated by genera of Tethyan ancestry, including both Duvaliidae (Berriasibelus, Castellanibelus, Duvalia, Pseudobelus) and Belemnopseidae (Adiakritobelus, Hibolithes, Mirabelobelus, Vaunagites). These two groups of Tethyan taxa comprise more than 99.9% of the belemnite‐rich assemblages of the Valanginian of the VB. The occurrence of a boreal specimen documents an isolated immigration of belemnites from the north in the early Valanginian. At the same time most Tethyan belemnite taxa are absent from the Boreal Realm, only Duvalia, Pseudobelus and Hibolithes have been described from North‐East Greenland, and Hibolithes from Svalbard. Based on these diverging biogeographical patterns of the Tethyan belemnite genera we establish two taxonomically different belemnite faunas: Tethyan Fauna 1 (Duvalia, Pseudobelus, Hibolithes), which has a near global, Tethyan‐wide and even boreal distribution, and Tethyan Fauna 2 (Adiakritobelus, Berriasibelus, Castellanibelus, Mirabelobelus, Vaunagites), which is less widely distributed and is restricted to southern Europe. These different spatial distribution patterns shed light on the ecology, migration patterns and evolution of Early Cretaceous belemnites.
    Keywords: ddc:564.5
    Language: English
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    Ensemble Kalman filter based data assimilation for tropical waves in the MJO skeleton model (2022)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2022-10-06
    Description: The Madden–Julian oscillation (MJO) is the dominant component of tropical intraseasonal variability, with wide‐reaching impacts even on extratropical weather and climate patterns. However, predicting the MJO is challenging. One reason is the suboptimal state estimates obtained with standard data assimilation (DA) approaches. These are typically based on filtering methods with Gaussian approximations and do not take into account physical properties that are important specifically for the MJO. In this article, a constrained ensemble DA method is applied to study the impact of different physical constraints on the state estimation and prediction of the MJO. The quadratic programming ensemble (QPEns) algorithm utilized extends the standard stochastic ensemble Kalman filter (EnKF) with specifiable constraints on the updates of all ensemble members. This allows us to recover physically more consistent states and to respect possible associated non‐Gaussian statistics. The study is based on identical twin experiments with an adopted nonlinear model for tropical intraseasonal variability. This so‐called skeleton model succeeds in reproducing the main large‐scale features of the MJO and closely related tropical waves, while keeping adequate simplicity for fast experiments on intraseasonal time‐scales. Conservation laws and other crucial physical properties from the model are examined as constraints in the QPEns. Our results demonstrate an overall improvement in the filtering and forecast skill when the model's total energy is conserved in the initial conditions. The degree of benefit is found to be dependent on the observational setup and the strength of the model's nonlinear dynamics. It is also shown that, even in cases where the statistical error in some waves remains comparable with the stochastic EnKF during the DA stage, their prediction is improved remarkably when using the initial state resulting from the QPEns.
    Description: Unsatisfactory predictions of the MJO are partly due to DA methods that do not respect non‐Gaussian PDFs and the physical properties of the tropical atmosphere. Therefore the QPEns, an algorithm extending a stochastic EnKF with state constraints, is tested here on a simplified model for the MJO and associated tropical waves. Our series of identical twin experiments shows, in particular, that a constraint on the truth's nonlinear total energy improves forecasts statistically and can, in certain situations, even prevent filter divergence. image
    Description: Deutsche Forschungsgemeinschaft : Heisenberg Award (DFG JA1077/4‐1); Transregional Collaborative Research Center SFB / TRR 165 “Waves to Weather” http://dx.doi.org/10.13039/501100001659
    Description: Office of Naval Research (ONR) http://dx.doi.org/10.13039/100000006
    Keywords: ddc:551.6
    Language: English
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    Modeling the Transport and Deposition of 10Be Produced by the Strongest Solar Proton Event During the Holocene (2022)
    Details
    Publication Date: 2022-10-06
    Description: Prominent excursions in the number of cosmogenic nuclides (e.g., 10Be) around 774 CE/775 document the most severe solar proton event (SPE) throughout the Holocene. Its manifestation in ice cores is valuable for geochronology, but also for solar‐terrestrial physics and climate modeling. Using the ECHAM/MESSy Atmospheric Chemistry (EMAC) climate model in combination with the Warning System for Aviation Exposure to SEP (WASAVIES), we investigate the transport, mixing, and deposition of the cosmogenic nuclide 10Be produced by the 774 CE/775 SPE. By comparing the model results to the reconstructed 10Be time series from four ice core records, we study the atmospheric pathways of 10Be from its stratospheric source to its sink at Earth's surface. The reconstructed post‐SPE evolution of the 10Be surface fluxes at the ice core sites is well captured by the model. The downward transport of the 10Be atoms is controlled by the Brewer‐Dobson circulation in the stratosphere and cross‐tropopause transport via tropopause folds or large‐scale sinking. Clear hemispheric differences in the transport and deposition processes are identified. In both polar regions the 10Be surface fluxes peak in summertime, with a larger influence of wet deposition on the seasonal 10Be surface flux in Greenland than in Antarctica. Differences in the peak 10Be surface flux following the 774 CE/775 SPE at the drilling sites are explained by specific meteorological conditions depending on the geographic locations of the sites.
    Description: Plain Language Summary: During large solar storms, high energy particles are hurled with enormous force toward Earth by the Sun. As these particles collide with atmospheric constituents (such as oxygen or nitrogen) unique nuclides of cosmogenic origin are formed in the higher atmosphere. From there they are transported downwards and finally precipitate at the surface due to different sink processes. Their imprints can be conserved over thousands of years within natural archives, such as ice cores or tree rings. Analysis of these natural archives around the globe indicates that the strongest solar storm over the last 10.000 years happened around 774 CE/775. This event is estimated to have been up to two orders of magnitude stronger, than the strongest known events documented for the satellite era. In this study, we model and analyze the transport and deposition of the cosmogenic nuclides produced by the extreme 774 CE/775 event, by applying a new experimental setup. Our results might help to interpret the fingerprints of historical extreme events with respect to the prevailing atmospheric conditions.
    Description: Key Points: The modeled transport and deposition of the cosmogenic nuclide10Be produced by the 774/775 solar proton event was compared to 10Be ice core records. Hemispheric differences in stratospheric and cross‐tropopause transport, and deposition were identified, with polar summertime maxima of 10Be surface flux. Differences in reconstructed10Be surface fluxes are explained by the local ratio of wet to dry deposition maximizing in the summertime.
    Description: MEXT Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691
    Keywords: ddc:551.5
    Language: English
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    Nonmarine Ostracoda as proxies in (geo‐)archaeology — A review (2022)
    Details
    Publication Date: 2022-10-06
    Description: Ostracods as bioindicators are extremely useful for reconstructing palaeoenvironment and palaeoclimate and can also indicate the provenance of sediments and materials, for example, in studies on ancient commercial networks. Ostracods are small crustaceans that live in almost all aquatic habitats, both natural and man‐made. Due to their calcitic carapace, they have high fossilization potential, and their use in geoarchaeology has been steadily increasing during the last decades. Their small size needs mean that only small volumes of sediment samples are needed, and species‐specific ecological tolerances and preferences allow detailed palaeoenvironmental reconstructions. Typical methods of their application are palaeoecological analyses of associations based on ecological information and taphonomy, morphometric variability and stable isotope and chemistry analyses of their shells. The present paper aims to present an overview of applications of non‐marine ostracods in (geo‐)archaeological research, recommending sampling and analytical techniques for addressing archaeological research questions on palaeoclimate, habitat and landscape changes, water availability and quality, land use and other anthropogenic impacts, the provenance of materials and commercial networks to promote the application of Ostracoda in geoarchaeology/environmental archaeology.
    Description: International Max Planck Research School for the Science of Human History
    Keywords: ddc:565.3
    Language: English
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    The effect of stochastically perturbed parametrisation tendencies (SPPT) on rapidly ascending air streams (2022)
    John Wiley & Sons, Ltd | Chichester, UK
    Details
    Publication Date: 2022-10-06
    Description: The stochastically perturbed parametrisation tendency (SPPT) scheme is a well‐established technique in ensemble forecasting to address model uncertainty by introducing perturbations into the tendencies provided by the physics parametrisations. The magnitude of the perturbations scales with the local net parametrisation tendency, resulting in large perturbations where diabatic processes are active. Rapidly ascending air streams, such as warm conveyor belts (WCBs) and organized tropical convection, are often driven by cloud diabatic processes and are therefore prone to such perturbations. This study investigates the effects of SPPT and initial condition perturbations on rapidly ascending air streams by computing trajectories in sensitivity experiments with the European Centre for Medium‐Range Weather Forecasts (ECMWF) ensemble prediction system, which are set up to disentangle the effects of initial conditions and physics perturbations. The results demonstrate that SPPT systematically increases the frequency of rapidly ascending air streams. The effect is observed globally, but is enhanced in regions where the latent heating along the trajectories is larger. Despite the frequency changes, there are only minor modifications to the physical properties of the trajectories due to SPPT. In contrast to SPPT, initial condition perturbations do not affect WCBs and tropical convection systematically. An Eulerian perspective on vertical velocities reveals that SPPT increases the frequency of strong upward motions compared with experiments with unperturbed model physics. Consistent with the altered vertical motions, precipitation rates are also affected by the model physics perturbations. The unperturbed control member shows the same characteristics as the experiments without SPPT regarding rapidly ascending air streams. We make use of this to corroborate the findings from the sensitivity experiments by analyzing the differences between perturbed and unperturbed members in operational ensemble forecasts of ECMWF. Finally, we give an explanation of how symmetric, zero‐mean perturbations can lead to a unidirectional response when applied in a nonlinear system.
    Description: The stochastically perturbed parametrisation tendencies (SPPT) scheme is used at ECMWF to perturb the model physics and introduces state‐dependent perturbations into the parametrisation tendencies. The frequency of rapidly ascending air streams is systematically enhanced when SPPT is active. This effect is stronger when the latent heating is large (panel a), and is therefore more pronounced in the Tropics than in the Extratropics. In contrast, the impact of SPPT on the physical properties of the air streams, such as the latent heat release, is very small (panel b).
    Description: Helmholtz Young Investigator Group ‘Sub‐ Seasonal Predictability: Understanding the Role of Diabatic Outflow’
    Keywords: ddc:551.5
    Language: English
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    Mapping the Brightness of Ganymede's Ultraviolet Aurora Using Hubble Space Telescope Observations (2022)
    Details
    Publication Date: 2022-10-06
    Description: We analyze Hubble Space Telescope observations of Ganymede made with the Space Telescope Imaging Spectrograph between 1998 and 2017 to generate a brightness map of Ganymede's oxygen emission at 1,356 Å. Our Mercator projected map demonstrates that the brightness along Ganymede's northern and southern auroral ovals strongly varies with longitude. To quantify this variation around Ganymede, we investigate the brightness averaged over 36°‐wide longitude corridors centered around the sub‐Jovian (0° W), leading (90° W), anti‐Jovian (180° W), and trailing (270° W) central longitudes. In the northern hemisphere, the brightness of the auroral oval is 3.7 ± 0.4 times lower in the sub‐Jovian and anti‐Jovian corridors compared to the trailing and leading corridors. The southern oval is overall brighter than the northern oval, and only 2.5 ± 0.2 times fainter on the sub‐ and anti‐Jovian corridors compared to the trailing and leading corridors. This demonstrates that Ganymede's auroral ovals are strongly structured in auroral crescents on the leading side (plasma downstream side) and on the trailing side (plasma upstream side). We also find that the brightness is not symmetric with respect to the 270° meridian, but shifted by ∼20° towards the Jovian‐facing hemisphere. Our map will be useful for subsequent studies to understand the processes that generate the aurora in Ganymede's non‐rotationally driven, sub‐Alfvénic magnetosphere.
    Description: Plain Language Summary: Northern lights often illuminate the night sky in a shimmering green or red tone at high geographic latitudes. This emission, scientifically referred to as aurora, is a result of electrically charged particles that move along Earth's magnetic field lines and interact with its atmosphere to produce auroral emission. Apart from the Earth, multiple other planets in our solar system also exhibit auroral emission. By characterizing the brightness and structure of these lights, we are therefore able to deduce insights about a planet's atmosphere, magnetic field and the physical processes occurring along the field lines from afar. In this work, we used observations from the Hubble Space Telescope to analyze the auroral emission of Jupiter's largest moon Ganymede. We combined multiple images of Ganymede to create the first complete map that displays the auroral brightness. Our map revealed that the emission on Ganymede's auroral ovals varies strongly in brightness with divisions into two distinct bright and faint regions. They resemble two auroral crescents in the north and south respectively, and demonstrate the uniqueness of Ganymede's aurora in comparison with the auroral ovals of other planets in the solar system.
    Description: Key Points: Brightness map of Ganymede's ultraviolet auroral emission has been constructed based on Hubble Space Telescope observations from 1998 to 2017. Auroral ovals are structured in upstream and downstream “crescents”. Brightness on sub‐Jovian and anti‐Jovian side is strongly reduced by a factor of 3–4 compared to upstream and downstream side.
    Description: European Research Council (ERC)
    Description: http://archive.stsci.edu/hst/
    Keywords: ddc:523
    Language: English
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    Tropical Continents Rainier Than Expected From Geometrical Constraints (2022)
    Details
    Publication Date: 2022-10-06
    Description: Abundant rainfall over tropical land masses sustains rich ecosystems, a crucial source of biodiversity and sink of carbon. Here, we use two characteristics of the observed tropical precipitation distribution, its distinctive zonal arrangement and its partitioning between land and ocean, to understand whether land conditions the climate to receive more than its fair share of precipitation as set by the land‐sea distribution. Our analysis demonstrates that it is not possible to explain the tropics‐wide partitioning of precipitation unless one assumes that rain is favored over land. Land receives more than its fair share of precipitation by broadening and letting the tropical rainbelts move more, effectively underpinning a negative feedback between surface water storage and precipitation. In contrast, rain is disfavored over land in climate models. Our findings suggest that the abundance of rainfall that shapes the terrestrial tropical biosphere is more robust to perturbations than models have suggested.
    Description: Plain Language Summary: Many ecosystems depend on the presence of a land surface exposed to precipitation to exist and prosper. In contrast to the marine biota, though, the terrestrial biosphere cannot directly tap into an unlimited reservoir of water molecules that can be recycled to support life. Yet, observations indicate that it rains in mean 3 mm day−1 over tropical land and 3 mm day−1 over tropical ocean, giving the surprising impression that precipitation amounts are not altered by the presence of land. Investigating the factors controlling this tropics‐wide partitioning of precipitation, we show that geometrical constraints actually would lead to a precipitation ratio of 0.86, not 1.0, if the presence of land would not matter. Comparing this theoretical value to observations, we find that the land receives more than its fair share of precipitation. This happens by broadening and letting the tropical rainbelt moves more over land. By quantifying the strength of the land control on the tropics‐wide partitioning of precipitation, we can also deduce that a negative feedback exists between evapotranspiration and precipitation. In contrast, repeating the same analysis with climate models reveals a positive feedback, questioning the ability of climate models to simulate regional tropical precipitation changes.
    Description: Key Points: A conceptual model of tropical precipitation is derived to understand the tropics‐wide partitioning of precipitation between land and ocean. The size and location of continent constrain the tropical land‐to‐ocean precipitation ratio to lie between 0.74 and 0.95 with a mean of 0.86. Observed ratios from six data sets are larger than these values, indicating that land receives more than its fair share of precipitation.
    Description: http://hdl.handle.net/21.11116/0000-000A-1DEC-D
    Keywords: ddc:551.6
    Language: English
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    Strain Signals Governed by Frictional‐Elastoplastic Interaction of the Upper Plate and Shallow Subduction Megathrust Interface Over Seismic Cycles (2022)
    Details
    Publication Date: 2022-10-06
    Description: The behavior of the shallow portion of the subduction zone, which generates the largest earthquakes and devastating tsunamis, is still insufficiently constrained. Monitoring only a fraction of a single megathrust earthquake cycle and the offshore location of the source of these earthquakes are the foremost reasons for the insufficient understanding. The frictional‐elastoplastic interaction between the megathrust interface and its overlying wedge causes variable surface strain signals such that the wedge strain patterns may reveal the mechanical state of the interface. To contribute to this understanding, we employ Seismotectonic Scale Modeling and simplify elastoplastic megathrust subduction to generate hundreds of analog seismic cycles at a laboratory scale and monitor the surface strain signals over the model's forearc across high to low temporal resolutions. We establish two compressional and critical wedge configurations to explore the mechanical and kinematic interaction between the shallow wedge and the interface. Our results demonstrate that this interaction can partition the wedge into different segments such that the anelastic extensional segment overlays the seismogenic zone at depth. Moreover, the different segments of the wedge may switch their state from compression/extension to extension/compression domains. We highlight that a more segmented upper plate represents megathrust subduction that generates more characteristic and periodic events. Additionally, the strain time series reveals that the strain state may remain quasi‐stable over a few seismic cycles in the coastal zone and then switch to the opposite mode. These observations are crucial for evaluating earthquake‐related morphotectonic markers and short‐term interseismic time series of the coastal regions.
    Description: Key Points: Analog earthquake cycle experiments provide observations to evaluate the surface strain signals from the shallow megathrust. The extensional segment of the forearc overlays the seismogenic zone at depth. The strain state may remain quasi‐stable over a few seismic cycles in the coastal zone.
    Description: SUBITOP Marie Sklodowska‐Curie Action project from the European Union's EU Framework Programme
    Description: Deutsche Forschungsgemeinschaft (CRC 1114) “Scaling Cascades in Complex Systems”
    Description: https://doi.org/10.5880/fidgeo.2022.015
    Keywords: ddc:551.8 ; ddc:550.78
    Language: English
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    Mixed Layer Depth Promotes Trophic Amplification on a Seasonal Scale (2022)
    Details
    Publication Date: 2022-10-06
    Description: The Humboldt Upwelling System is of global interest due to its importance to fisheries, though the origin of its high productivity remains elusive. In regional physical‐biogeochemical model simulations, the seasonal amplitude of mesozooplankton net production exceeds that of phytoplankton, indicating “seasonal trophic amplification.” An analytical approach identifies amplification to be driven by a seasonally varying trophic transfer efficiency due to mixed layer variations. The latter alters the vertical distribution of phytoplankton and thus the zooplankton and phytoplankton encounters, with lower encounters occurring in a deeper mixed layer where phytoplankton are diluted. In global model simulations, mixed layer depth appears to affect trophic transfer similarly in other productive regions. Our results highlight the importance of mixed layer depth for trophodynamics on a seasonal scale with potential significant implications, given mixed layer depth changes projected under climate change.
    Description: Plain Language Summary: The Humboldt Upwelling System is a fishery‐important region. A common assumption is that a certain amount of phytoplankton supports a proportional amount of fish. However, we find that a small seasonal change in phytoplankton can trigger a larger variation in zooplankton. This implies that one may underestimate changes in fish solely based on phytoplankton. Using ecosystem model simulations, we investigate why changes of phytoplankton are not proportionally reflected in zooplankton. The portion of phytoplankton that ends up in zooplankton is controlled by the changing depth of the surface ocean “mixed layer.” The “mixed layer” traps both the phytoplankton and zooplankton in a limited amount of space. When the “mixed layer” is shallow, zooplankton can feed more efficiently on phytoplankton as both are compressed in a comparatively smaller space. We conclude that in the Humboldt System, and other “food‐rich” regions, feeding efficiently, determined by the “mixed layer,” is more important than how much food is available.
    Description: Key Points: Environmental factors strongly affect plankton trophodynamics on a seasonal scale. Seasonal trophic amplification in the Humboldt system is driven by mixed layer dynamics. Mixed layer depth and food chain efficiency correlate also in other productive regions.
    Description: China Sponsorship Council
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:577.7
    Language: English
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    Improving the Vertical Modeling of Tropospheric Delay (2022)
    Details
    Publication Date: 2022-10-06
    Description: Accurate tropospheric delays from Numerical Weather Models (NWM) are an important input to space geodetic techniques, especially for precise real‐time Global Navigation Satellite Systems, which are indispensable to earthquake and tsunami early warning systems as well as weather forecasting. The NWM‐based tropospheric delays are currently provided either site‐specific with a limited spatial coverage, or on two‐dimensional grids close to the Earth surface, which cannot be used for high altitudes. We introduce a new method of representing NWM‐derived tropospheric zenith hydrostatic and wet delays. A large volume of NWM‐derived data is parameterized with surface values and additional two or three coefficients for their vertical scaling to heights up to 14 km. A precision of 1–2 mm is achieved for reconstructing delays to the NWM‐determined delays at any altitudes. The method can efficiently deliver NWM‐derived tropospheric delays to a broader community of space geodetic techniques.
    Description: Plain Language Summary: Precise positioning with microwave‐based space geodetic techniques, such as Global Navigation Satellite Systems (GNSS), requires accurate modeling of the atmospheric refraction. Numerical Weather Models (NWM) can provide tropospheric delays with an accuracy of 1–2 cm in zenith direction and are therefore useful for improving the data analysis. However, due to the large data volume to handle, NWM‐based products are typically provided only for selected sites, or on a global grid referring to a specific height. We provide an efficient method to represent the vertical profile of tropospheric delay from the Earth surface up to 14 km altitude with a precision of 1–2 mm. The method is used to preserve the precision of NWM‐derived tropospheric delays at the altitudes using three to four coefficients per geographic location (longitude, latitude) at the ground. This paves the way of applying the NWM‐based accurate tropospheric delays in space geodetic data analysis, especially for global augmentations of real‐time GNSS, which play a critical role in the rapid characterization and early warning of geohazards such as earthquake and tsunami, as well as kinematic platforms of high altitudes.
    Description: Key Points: New method for precise modeling of the zenith hydrostatic and wet delays from the Earth surface up to an altitude of 14 km. Tropospheric delay vertical modeling precision of better than 3 mm is achieved on a global scale. The method provides numerical weather model‐derived precise tropospheric augmentation correction for real‐time space geodetic techniques.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: China Scholarship Council CSC
    Description: Helmholtz OCPC Program
    Description: https://cds.climate.copernicus.eu/cdsapp
    Keywords: ddc:551.5
    Language: English
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    Geowissenschaftliche Mitteilungen - GMIT 87 (2022)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2022-06-27
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2022 enthält die Themenblöcke: GEOfokus: (Archäometrie in Deutschland), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: ddc:550
    Language: German
    Type: doc-type:book , publishedVersion
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    Geowissenschaftliche Mitteilungen - GMIT 88 (2022)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2022-06-27
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2022 enthält die Themenblöcke: GEOfokus: Die marine Seismik der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Description: DFG, SUB Göttingen
    Description: journal
    Keywords: ddc:550
    Language: German
    Type: doc-type:book , publishedVersion
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    Bergordnung für den Schreckenberg 1499/1500 (2022)
    Details
    Publication Date: 2022-07-01
    Description: Bergordnung für die Bergwerke am Schreckenberg, bei Annaberg, von 1499/1500. Der Ursprung dieser Bergordnung geht auf einen Befehl Herzog Georgs von Sachsen zur Regelung des Bergbaus auf dem Schreckenberg zurück. Basis dieser Bergordnung bildet die Bergordnung für den Schneeberg vom 7. April 1497. In den insgesamt 102 Paragraphen der Bergordnung wurden der gesamte Bergwerksbetrieb, die Arbeit der Schmelzhütten und das Gericht auf dem Schreckenberg geregelt.
    Description: source
    Language: German
    Type: doc-type:book , updatedVersion
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    Bergordnung für St. Annaberg 1509 (2022)
    Details
    Publication Date: 2022-09-05
    Description: Bergordnung für St. Annaberg, vom 5. Februar 1509. Basis dieser Bergordnung bildet die Bergordnungen für den Schreckenberg von 1499/1500. In den insgesamt 103 Paragraphen der Bergordnung wurden der gesamte Bergwerksbetrieb, die Arbeit der Schmelzhütten und das Gericht in St. Annaberg geregelt. Neu sind die Eide der Bergbeamten. Diese Bergordnung gilt als die erste gedruckte Bergordnung überhaupt. Aufgrund ihrer Ausführlichkeit und Komplexität bildete sie die Grundlage für nachfolgende Bergordnungen in ganz Europa.
    Description: source
    Keywords: ddc:622 ; ddc:343.077
    Language: German
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    Geochronology and petrogenesis of granitoids and associated mafic enclaves from Ghohroud in the Urumieh–Dokhtar Magmatic Arc (Iran): Evidence for magma mixing during the closure of the Neotethyan Ocean (2022)
    Khaksar, Tayebeh ; Rashidnejad‐Omran, Nematollah ; Li, Shuang‐Qing ; [et al.]
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-09-25
    Description: The Ghohroud granitoids (GG), containing mafic microgranular enclaves (MMEs) are located in the central part of the Urumieh‐Dokhtar Magmatic Arc (UDMA) in central Iran. They are associated with the subduction‐related magmatism in the Alpine‐Himalayan orogenic belt. The GG are comprised of a variety of intermediate and felsic rocks, including tonalite, granodiorite, granite, diorite porphyry and monzodiorite. The MMEs are gabbroic diorite and tonalite in composition and characterized by a fine‐grained hypidiomorphic microgranular texture with occasional chilled margins. They show rounded, sharp or irregular contact with the host granitoids. The occurrences of quartz, K‐feldspar and corroded plagioclase indicate that MMEs are the products of mixing between mantle and crust‐derived magmas. New ages of zircon U–Pb dating reveal that the GG in the Kashan area emplaced at ca. 19–17 Ma (Burdigalian). All the samples of MMEs and granitoid host rocks in this study are metaluminous and calc‐alkaline with I‐type affinities. They are enriched in light rare earth elements (LREEs) and show slight negative Eu anomalies (Eu/Eu* = 0.36–0.95). These features in a combination with the relative depletion in Nb, Ta, Ti and P, indicate the granitoids and MMEs are closely associated with subduction‐related magmas at an active continental margin. The host rocks yield relatively homogeneous isotopic compositions of initial 87Sr/86Sr ratios ranging from 0.706036 to 0.707055, εNd(t) values varying from −2.25 to 0.8, and the Nd model ages (TDM) vary in a limited range of 0.70–0.96 Ga. The MMEs show similar initial 87Sr/86Sr ratios (0.706420–0.707366), εNd(t) values (−1.32 to −0.27), TDM (0.68–1.09 Ga) and Pb isotopic compositions with host granitoids, which imply they attained isotopic equilibration during magma mingling and mixing. In combination with the petrographic, chemical and isotopic results, we suggest that the origin of MMEs and their host rocks were related to the interaction between crust‐derived melts and mantle‐derived mafic magmas. The magma‐mixing event possibly occurred during the transition from subduction to collision in the UDMA along with the closure of the Neotethyan ocean.
    Description: A comprehensive dataset from petrographic characteristics to geochemical compositions of the mafic microgranular enclaves and granitoid host rocks from the Urumieh–Dokhtar Magmatic Arc (Iran) was presented. The new data provide significant insight into the evolution of magmatism in this area, which was tightly related to the Neotethyan closure. image
    Description: National Nature Science Foundation of China
    Description: TMU Research Grant Council
    Keywords: ddc:552.3
    Language: English
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    Multivariate Bias‐Correction of High‐Resolution Regional Climate Change Simulations for West Africa: Performance and Climate Change Implications (2022)
    Dieng, Diarra ; Cannon, Alex J. ; Laux, Patrick ; [et al.]
    Details
    Publication Date: 2022-09-22
    Description: A multivariate bias correction based on N‐dimensional probability density function transform (MBCn) technique is applied to four different high‐resolution regional climate change simulations and key meteorological variables, namely precipitation, mean near‐surface air temperature, near‐surface maximum air temperature, near‐surface minimum air temperature, surface downwelling solar radiation, relative humidity, and wind speed. The impact of bias‐correction on the historical (1980–2005) period, the inter‐variable relationships, and the measures of spatio‐temporal consistency are investigated. The focus is on the discrepancies between the original and the bias‐corrected results over five agro‐ecological zones. We also evaluate relevant indices for agricultural applications such as climate extreme indices, under current and future (2020–2050) climate change conditions based on the RCP4.5. Results show that MBCn successfully corrects the seasonal biases in spatial patterns and intensities for all variables, their intervariable correlation, and the distributions of most of the analyzed variables. Relatively large bias reductions during the historical period give indication of possible benefits of MBCn when applied to future scenarios. Although the four regional climate models do not agree on the same positive/negative sign of the change of the seven climate variables for all grid points, the model ensemble mean shows a statistically significant change in rainfall, relative humidity in the Northern zone and wind speed in the Coastal zone of West Africa and increasing maximum summer temperature up to 2°C in the Sahara.
    Description: Key Points: Multivariate bias‐correction (MBCn) of key meteorological variables accounting for their interdependency. MBCn effectively removes the statistical biases as indicated by several measures and improves the representation of the probability density. The corrected model ensemble mean preserves the climate change signal with a statistically significant change in precipitation.
    Description: Climate Change and Health in sub‐Saharan Africa project
    Description: https://doi.org/10.1594/PANGAEA.880512
    Description: http://doi.org/10.5281/zenodo.1255882
    Language: English
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    Sea Ice Rheology Experiment (SIREx): 2. Evaluating Linear Kinematic Features in High‐Resolution Sea Ice Simulations (2022)
    Details
    Publication Date: 2022-09-22
    Description: Simulating sea ice drift and deformation in the Arctic Ocean is still a challenge because of the multiscale interaction of sea ice floes that compose the Arctic Sea ice cover. The Sea Ice Rheology Experiment (SIREx) is a model intercomparison project of the Forum of Arctic Modeling and Observational Synthesis (FAMOS). In SIREx, skill metrics are designed to evaluate different recently suggested approaches for modeling linear kinematic features (LKFs) to provide guidance for modeling small‐scale deformation. These LKFs are narrow bands of localized deformation that can be observed in satellite images and also form in high resolution sea ice simulations. In this contribution, spatial and temporal properties of LKFs are assessed in 36 simulations of state‐of‐the‐art sea ice models and compared to deformation features derived from the RADARSAT Geophysical Processor System. All simulations produce LKFs, but only very few models realistically simulate at least some statistics of LKF properties such as densities, lengths, or growth rates. All SIREx models overestimate the angle of fracture between conjugate pairs of LKFs and LKF lifetimes pointing to inaccurate model physics. The temporal and spatial resolution of a simulation and the spatial resolution of atmospheric boundary condition affect simulated LKFs as much as the model's sea ice rheology and numerics. Only in very high resolution simulations (≤2 km) the concentration and thickness anomalies along LKFs are large enough to affect air‐ice‐ocean interaction processes.
    Description: Plain Language Summary: Winds and ocean currents continuously move and deform the sea ice cover of the Arctic Ocean. The deformation eventually breaks an initially closed ice cover into many individual floes, piles up floes, and creates open water. The distribution of ice floes and open water between them is important for climate research, because ice reflects more light and energy back to the atmosphere than open water, so that less ice and more open water leads to warmer oceans. Current climate models cannot simulate sea ice as individual floes. Instead, a variety of methods is used to represent the movement and deformation of the sea ice cover. The Sea Ice Rheology Experiment (SIREx) compares these different methods and assesses the deformation of sea ice in 36 numerical simulations. We identify and track deformation features in the ice cover, which are distinct narrow areas where the ice is breaking or piling up. Comparing specific spatial and temporal properties of these features, for example, the different amounts of fractured ice in specific regions, or the duration of individual deformation events, to satellite observations provides information about the realism of the simulations. From this comparison, we can learn how to improve sea ice models for more realistic simulations of sea ice deformation.
    Description: Key Points: All models simulate linear kinematic features (LKFs), but none accurately reproduces all LKF statistics. Resolved LKFs are affected strongest by spatial and temporal resolution of model grid and atmospheric forcing and rheology. Accurate scaling of deformation rates is a proxy only for realistic LKF numbers but not for any other LKF static.
    Description: DOE
    Description: HYCOM NOPP
    Description: Innovation Fund Denmark and the Horizon 2020 Framework Programme of the European Union
    Description: National centre for Climate Research, SALIENSEAS, ERA4CS
    Description: German Helmholtz Climate Initiative REKLIM (Regional Climate Change)
    Description: Gouvernement du Canada, Natural Sciences and Engineering Research Council of Canada (NSERC) http://dx.doi.org/10.13039/501100000038
    Description: Environment and Climate Change Canada Grants & Contributions program
    Description: Office of Naval Research Arctic and Global Prediction program
    Description: U.S. Department of Energy Regional and Global Model Analysis program
    Description: National Science Foundation Arctic System Science program
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://zenodo.org/communities/sirex
    Keywords: ddc:550.285
    Language: English
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    Sedimentary DNA identifies modern and past macrophyte diversity and its environmental drivers in high‐latitude and high‐elevation lakes in Siberia and China (2022)
    Stoof‐Leichsenring, Kathleen R. ; Huang, Sichao ; Liu, Sisi ; [et al.]
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-09-22
    Description: Arctic and alpine aquatic ecosystems are changing rapidly under recent global warming, threatening water resources by diminishing trophic status and changing biotic composition. Macrophytes play a key role in the ecology of freshwaters and we need to improve our understanding of long‐term macrophytes diversity and environmental change so far limited by the sporadic presence of macrofossils in sediments. In our study, we applied metabarcoding using the trnL P6 loop marker to retrieve macrophyte richness and composition from 179 surface‐sediment samples from arctic Siberian and alpine Chinese lakes and three representative lake cores. The surface‐sediment dataset suggests that macrophyte richness and composition are mostly affected by temperature and conductivity, with highest richness when mean July temperatures are higher than 12°C and conductivity ranges between 40 and 400 μS cm−1. Compositional turnover during the Late Pleistocene/Holocene is minor in Siberian cores and characterized by a less rich, but stable emergent macrophyte community. Richness decreases during the Last Glacial Maximum and rises during wetter and warmer climate in the Late‐glacial and Mid‐Holocene. In contrast, we detect a pronounced change from emergent to submerged taxa at 14 ka in the Tibetan alpine core, which can be explained by increasing temperature and conductivity due to glacial runoff and evaporation. Our study provides evidence for the suitability of the trnL marker to recover modern and past macrophyte diversity and its applicability for the response of macrophyte diversity to lake‐hydrochemical and climate variability predicting contrasting macrophyte changes in arctic and alpine lakes under intensified warming and human impact.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: Second Tibetan Plateau Scientific Expedition and Research Program
    Description: https://doi.pangaea.de/10.1594/PANGAEA.920866
    Description: https://doi.org/10.5061/dryad.k6djh9w4r
    Keywords: ddc:577.63
    Language: English
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    Controls of the Foreland Deformation Pattern in the Orogen‐Foreland Shortening System: Constraints From High‐Resolution Geodynamic Models (2022)
    Details
    Publication Date: 2022-09-22
    Description: Controls on the deformation pattern (shortening mode and tectonic style) of orogenic forelands during lithospheric shortening remain poorly understood. Here, we use high‐resolution 2D thermomechanical models to demonstrate that orogenic crustal thickness and foreland lithospheric thickness significantly control the shortening mode in the foreland. Pure‐shear shortening occurs when the orogenic crust is not thicker than the foreland crust or thick, but the foreland lithosphere is thin (〈70–80 km, as in the Puna foreland case). Conversely, simple‐shear shortening, characterized by foreland underthrusting beneath the orogen, arises when the orogenic crust is much thicker. This thickened crust results in high gravitational potential energy in the orogen, which triggers the migration of deformation to the foreland under further shortening. Our models present fully thick‐skinned, fully thin‐skinned, and intermediate tectonic styles in the foreland. The first tectonics forms in a pure‐shear shortening mode whereas the others require a simple‐shear mode and the presence of thick (〉∼4 km) sediments that are mechanically weak (friction coefficient 〈∼0.05) or weakened rapidly during deformation. The formation of fully thin‐skinned tectonics in thick and weak foreland sediments, as in the Subandean Ranges, requires the strength of the orogenic upper lithosphere to be less than one‐third as strong as that of the foreland upper lithosphere. Our models successfully reproduce foreland deformation patterns in the Central and Southern Andes and the Laramide province.
    Description: Key Points: Thicknesses of the orogenic crust and the foreland lithosphere control the foreland shortening mode (pure‐shear or simple‐shear). Foreland weak sediments and the upper lithosphere of the weaker orogen control the foreland tectonic style (thin‐skinned or thick‐skinned). High‐resolution geodynamic models successfully reproduce foreland deformation patterns in several natural orogen‐foreland shortening systems.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://bitbucket.org/bkaus/LaMEM
    Description: https://doi.org/10.5281/zenodo.5963016
    Keywords: ddc:551.8
    Language: English
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    Using Clustering, Statistical Modeling, and Climate Change Projections to Analyze Recent and Future Region‐Specific Compound Ozone and Temperature Burden Over Europe (2022)
    Details
    Publication Date: 2022-09-22
    Description: High ground‐level ozone concentrations and high air temperatures present two health‐relevant natural hazards. The most severe health outcomes are generally associated with concurrent elevated levels of both variables, representing so‐called compound ozone and temperature (o‐t‐) events. These o‐t‐events, their relationship with identified main meteorological and synoptic drivers, as well as ozone and temperature levels themselves and the linkage between both variables, vary temporally and with the location of sites. Due to the serious health burden and its spatiotemporal variations, the analysis of o‐t‐events across the European domain represents the focus of the current work. The main objective is to model and project present and future o‐t‐events, taking region‐specific differences into account. Thus, a division of the European domain into six o‐t‐regions with homogeneous, similar ground‐level ozone and temperature characteristics and patterns built the basis of the study. In order to assess region‐specific main meteorological and synoptic drivers of o‐t‐events, statistical downscaling models were developed for selected representative stations per o‐t‐region. Statistical climate change projections for all central European o‐t‐regions were generated to assess potential frequency shifts of o‐t‐events until the end of the 21st century. The output of eight Earth System Models from the sixth phase of the Coupled Model Intercomparison Project considering SSP245 and SSP370 scenario assumptions was applied. By comparing midcentury (2041–2060) and late century (2081–2100) time slice differences with respect to a historical base period (1995–2014), substantial increases of the health‐relevant compound o‐t‐events were projected across all central European regions.
    Description: Plain Language Summary: Compound events with concurrent high levels of ozone, being a major pollutant present in the air near Earth's surface, and of air temperature, have strong negative impacts on the health of humans. In this study, these compound events were investigated under present and future European climate. Six regions of similar ozone and temperature characteristics and patterns were defined. For each region, representative stations being typical examples for the overall region were extracted. Models for these stations were developed and their results analyzed to define factors that highly influence the occurrence of compound ozone and temperature events in each region, for example, mean air temperature or humidity levels. The generated models were later applied to project future frequency shifts of these compound events under climate change in central Europe. As a major result of the study, the future health‐relevant compound ozone and temperature events were projected to occur more frequently in the middle as well as at the end of the 21st century across all central European regions.
    Description: Key Points: A clustering approach based on ground‐level ozone and air temperature leads to a division of Europe into six ozone and temperature regions. Statistical downscaling models identify region‐specific main meteorological and synoptic drivers of compound ozone and temperature events. Climate change projections point to an increase in these compound events until the end of the 21st century in central Europe.
    Description: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)
    Keywords: ddc:551.6
    Language: English
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    Potential Links Between Tropospheric and Stratospheric Circulation Extremes During Early 2020 (2022)
    Details
    Publication Date: 2022-09-22
    Description: February‐March 2020 was marked by highly anomalous large‐scale circulations in the Northern extratropical troposphere and stratosphere. The Atlantic jet reached extreme strength, linked to some of the strongest and most persistent positive values of the Arctic Oscillation index on record, which provided conditions for extreme windstorms hitting Europe. Likewise, the stratospheric polar vortex reached extreme strength that persisted for an unusually long period. Past research indicated that such circulation extremes occurring throughout the troposphere‐stratosphere system are dynamically coupled, although the nature of this coupling is still not fully understood and generally difficult to quantify. We employ sets of numerical ensemble simulations to statistically characterize the mutual coupling of the early 2020 extremes. We find the extreme vortex strength to be linked to the reflection of upward propagating planetary waves and the occurrence of this reflection to be sensitive to the details of the vortex structure. Our results show an overall robust coupling between tropospheric and stratospheric anomalies: ensemble members with polar vortex exceeding a certain strength tend to exhibit a stronger tropospheric jet and vice versa. Moreover, members exhibiting a breakdown of the stratospheric circulation (e.g., sudden stratospheric warming) tend to lack periods of persistently enhanced tropospheric circulation. Despite indications for vertical coupling, our simulations underline the role of internal variability within each atmospheric layer. The circulation extremes during early 2020 may be viewed as resulting from a fortuitous alignment of dynamical evolutions within the troposphere and stratosphere, aided by each layer's modification of the other layer's boundary condition.
    Description: Key Points Large‐ensemble simulations are needed to fully characterize coupled extremes in the polar vortex and tropospheric jet in early 2020. Details of the vortex structure play an important role in promoting either reflection or dissipation of upward propagating waves 1 and/or 2. Modulation of lowermost stratospheric circulation from above and below facilitates co‐evolution of tropospheric and stratospheric extremes.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era5
    Description: https://doi.org/10.5282/ubm/data.281
    Description: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml
    Keywords: ddc:551.5
    Language: English
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    Seismic Velocity Recovery in the Subsurface: Transient Damage and Groundwater Drainage Following the 2015 Gorkha Earthquake, Nepal (2022)
    Details
    Publication Date: 2022-09-22
    Description: Shallow earthquakes frequently disturb the hydrological and mechanical state of the subsurface, with consequences for hazard and water management. Transient post‐seismic hydrological behavior has been widely reported, suggesting that the recovery of material properties (relaxation) following ground shaking may impact groundwater fluctuations. However, the monitoring of seismic velocity variations associated with earthquake damage and hydrological variations are often done assuming that both effects are independent. In a field site prone to highly variable hydrological conditions, we disentangle the different forcing of the relative seismic velocity variations δv retrieved from a small dense seismic array in Nepal in the aftermath of the 2015 Mw 7.8 Gorkha earthquake. We successfully model transient damage effects by introducing a universal relaxation function that contains a unique maximum relaxation timescale for the main shock and the aftershocks, independent of the ground shaking levels. Next, we remove the modeled velocity from the raw data and test whether the corresponding residuals agree with a background hydrological behavior we inferred from a previously calibrated groundwater model. The fitting of the δv data with this model is improved when we introduce transient hydrological properties in the phase immediately following the main shock. This transient behavior, interpreted as an enhanced permeability in the shallow subsurface, lasts for ∼6 months and is shorter than the damage relaxation (∼1 yr). Thus, we demonstrate the capability of seismic interferometry to deconvolve transient hydrological properties after earthquakes from non‐linear mechanical recovery.
    Description: Plain Language Summary: Earthquake ground shaking damage the rocks in the subsurface of the Earth, altering their strength and their permeability. After the main shock, the rock properties slowly return to their pre‐earthquake state, but the duration of this recovery is poorly constrained. One way to investigate these time‐dependent changes is through the monitoring of seismic velocity inferred from ambient ground vibration recorded at seismic stations. Here, we constrain the evolution of seismic velocity following the large 2015 Mw 7.8 Gorkha earthquake in Nepal, in a field site characterized by seasonal groundwater fluctuations. We find that the velocity recoveries after the main shock and the aftershocks can be modeled with the same recovery timescale, independently from the initial shaking intensity. This suggests that earthquakes of different sizes activate the same geological structures and mechanisms during the recovery phase. Thanks to the unique hydrological setting of our field site and a model that links seismic velocity and groundwater level, we also show that this change of rock properties after the main shock is accompanied by a transient change in hydrological properties, an observation inferred for the first time with seismic measurement.
    Description: Key Points: We estimate a recovery time scale (〈1 yr) in seismic velocity changes after the Gorkha earthquake using ambient noise correlations. Velocity recoveries are modeled with relaxation functions characterized by a constant maximum relaxation timescale that is peak ground velocity‐independent. We highlight a transient enhanced permeability from the velocity changes in the first ∼6 months following the main shock.
    Description: GFZ HART program
    Description: https://doi.org/10.5880/GFZ.4.6.2021.002
    Description: https://doi.org/10.14470/KA7560056170
    Keywords: ddc:551.22
    Language: English
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    The Height‐Dependent Delayed Ionospheric Response to Solar EUV (2022)
    Details
    Publication Date: 2022-09-22
    Description: Based on the analysis of electron density Ne profiles (Grahamstown ionosonde), a case study of the height‐dependent ionospheric response to two 27‐day solar rotation periods in 2019 is performed. A well‐defined sinusoidal response is observed for the period from 27 April 2019 to 24 May 2019 and reproduced with a Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulation. The occurring differences between model and observations as well as the driving physical and chemical processes are discussed based on the height‐dependent variations of Ne and major species. Further simulations with an artificial noise free sinusoidal solar flux input show that the Ne delay is defined by contributions due to accumulation of O+ at the Ne peak (positive delay) and continuous loss of O2+ in the lower ionosphere (negative delay). The neutral parts' 27‐day signatures show stronger phase shifts. The time‐dependent and height‐dependent impact of the processes responsible for the delayed ionospheric response can therefore be described by a joint analysis of the neutral and ionized parts. The return to the initial ionospheric state (and thus the loss of the accumulated O+) is driven by an increase of downward transport in the second half of the 27‐day solar rotation period. For this reason, the neutral vertical winds (upwards and downwards) and their different height‐dependent 27‐day signatures are discussed. Finally, the importance of a wavelength‐dependent analysis, statistical methods (superposed epoch analysis), and coupling with the middle atmosphere is discussed to outline steps for future analysis.
    Description: Key Points: A response to solar 27‐day signatures is observed in ionosonde Ne height profiles and successfully reproduced with a Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model simulation. Height‐dependent variations of the delayed ionospheric response are driven by the respective contributions of O+ and O2+. Transport processes have a significant impact on the 27‐day signatures of neutral and ionized parts in the upper atmosphere.
    Keywords: ddc:538.7 ; ddc:551.5
    Language: English
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    Alternating Emission Features in Io's Footprint Tail: Magnetohydrodynamical Simulations of Possible Causes (2022)
    Details
    Publication Date: 2022-09-22
    Description: Io's movement relative to the plasma in Jupiter's magnetosphere creates Alfvén waves propagating along the magnetic field lines which are partially reflected along their path. These waves are the root cause for auroral emission, which is subdivided into the Io Footprint (IFP), its tail and leading spot. New observations of the Juno spacecraft by Mura et al. (2018, https://doi.org/10.1126/science.aat1450) have shown puzzling substructure of the footprint and its tail. In these observations, the symmetry between the poleward and equatorward part of the footprint tail is broken and the tail spots are alternatingly displaced. We show that the location of these bright spots in the tail are consistent with Alfvén waves reflected at the boundary of the Io torus and Jupiter's ionosphere. Then, we investigate three different mechanisms to explain this phenomenon: (a) The Hall effect in Io's ionosphere, (b) travel time differences of Alfvén waves between Io's Jupiter facing and its opposing side and (c) asymmetries in Io's atmosphere. For that, we use magnetohydrodynamic simulations within an idealized geometry of the system. We use the Poynting flux near the Jovian ionosphere as a proxy for the morphology of the generated footprint and its tail. We find that the Hall effect is the most important mechanism under consideration to break the symmetry causing the “Alternating Alfvén spot street.” The travel time differences contributes to enhance this effect. We find no evidence that the inhomogeneities in Io's atmosphere contribute significantly to the location or shape of the tail spots.
    Description: Key Points: Hall effect in Io's ionosphere produces Poynting flux morphology similar to observed alternating Alfvén spot street in Io footprint tail (IFP). Alfvén wave travel time difference and asymmetries in Io's atmosphere are not sufficient to produce observed structures in IFP. IFP emission inter‐spot distance correlates with reflected Alfvén waves.
    Description: Regional Computing Center of the University of Cologne (RRZK)
    Description: European Research Council (ERC)
    Description: http://plutocode.ph.unito.it/download.html
    Keywords: ddc:523
    Language: English
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    Taxonomy and diversity of slit‐band gastropods (Order Pleurotomariida) and some slit bearing Caenogastropoda from the Pennsylvanian of the USA (2022)
    Details
    Publication Date: 2022-09-22
    Description: Pleurotomariida have the longest fossil record among living gastropods and are diverse and abundant in the middle and upper Palaeozoic. Its traditional classification is based on adult shell characters. The early shell morphology has been largely unknown. We describe exceptionally well‐preserved Pleurotomariida from the Pennsylvanian marine shales of Texas, Oklahoma, Kansas and Ohio. In total, 38 species representing 19 genera are described, including 10 new species, one new genus and one new subgenus: Eirlysella buckhornensis gen. et sp. nov., Shansiella (Oklahomaella) globilineata subgen. et sp. nov., Phymatopleura girtyi, Phymatopleura conica, Worthenia (Yochelsonospira) kuesi, Dictyotomaria turrisbabel, Paragoniozona yanceyi, Spiroscala shwedagoniformis, Peruvispira oklahomaensis, Baylea tenera. Replacement names are Paragoniozona ornata nom. nov. (for Pleurotomaria aspera Girty), Spiroscala quasipulchra nom. nov. (for Euconospira pulchra Batten). The early ontogenetic shells including protoconchs and early teleoconchs are reported in detail for the first time for most taxa. Most species have a protoconch of one whorl as that of living Vetigastropoda. Planktotrophic protoconchs (multi‐whorled larval shells with sinusigera) are reported for Platyzona and Peruvispira; they are therefore placed in the family Goniasmatidae (Caenogastropoda). Repaired shell scars were found in juvenile Pleurotomariida specimens (c. 1 mm), suggesting exposure to predation from an early stage of ontogeny. Pleurotomariida are strongly dominant in surface samples of the Finis Shale (Texas) but in bulk samples using fine mesh‐sizes, dominance is much less pronounced, indicating a change in clade proportion depending on sampling method. The taxonomic richness and abundance of Pleurotomariida seen in these Carboniferous shales have not been reported from post‐Triassic formations.
    Description: The Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:564
    Language: English
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    On gravity wave parameterisation in vicinity of low‐level blocking (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2022-09-22
    Description: This note is framed as an open question to the community regarding parameterisation schemes using the blocking layer depth to reduce the orographic gravity wave drag. It is the purpose of this note to argue that the current orographic gravity wave drag parameterisation in the vicinity of blocking is inadequate. Reducing the gravity wave amplitude (and thereby reducing the gravity wave drag) by assuming an effective mountain height dependent on the blocking depth is not realistic. The arguments given here will hopefully spark a debate and new considerations, ultimately leading to improvements in current orographic gravity wave drag parameterisations. This note illustrates that low‐level blocking can induce more gravity waves or gravity waves with a higher momentum flux (compared to the current parameterisation schemes). More realistic parameterisation schemes are likely to improve the models' performance. However, the fact is complex theories are needed to describe gravity wave excitation by orography so that it is difficult to represent gravity wave nature by a ‘too simple’ parameterisation scheme.
    Description: The purpose of this letter is to provide arguments that the current gravity wave drag parameterisation in the vicinity of blocking is inadequate. Reducing the gravity wave drag depending on the blocking depth is not a realistic representation. The letter lists five ways in which the blocking layer can result in a greater amount of gravity wave drag.
    Keywords: ddc:551.5
    Language: English
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    Bergordnung Herzog Albrecht II. von Österreich, Steyer und Kärnten für das Herzogtum Steiermark (2022)
    Details
    Publication Date: 2022-06-09
    Description: Bergordnung für das Herzogtum Steiermark von Herzog Albrecht II. von Österreich, Steiermark und Kärnten vom 14. August 1339. Obwohl in der Einleitung nur die Bürger und Bergleute von Zeiring genannt werden, galt diese Bergordnung für das gesamte Herzogtum Steiermark. In 25 Absätzen werden die grundlegenden Rechte und Pflichten beim Bergbau, dem Handel mit dessen Produkten sowie die Rechte und Pflichten der Bergbeamten aufgeführt.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German
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    Bergrecht von Iglau A (2022)
    Details
    Publication Date: 2022-06-09
    Description: Bergrecht von Iglau, bestätigt von König Wenzel I. von Böhmen und seinem Sohn Ottokar II. Přemysl, Markgraf von Mähren 1248/49. Niedergeschrieben im Anhang des Iglauer Stadtrechtes. Erstes umfassendes Bergrecht im damaligen deutschsprachigen Raum für das Königreich Böhmen. Festgelegt wurden hier die Grundsätze des Bergbaus. Spätere Bergordnungen berufen sich in der Ausgestaltung weiterer Regelungen auf das Iglauer Bergrecht.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German , Latin
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    Bergordnung Herzog Albrecht II. von Österreich, Steyer und Kärnten für das Herzogtum Steiermark (2022)
    Details
    Publication Date: 2022-06-09
    Description: Bergordnung für das Herzogtum Steiermark von Herzog Albrecht II. von Österreich, Steiermark und Kärnten vom 14. September 1336/1339. Inhaltlich gleicht diese Bergordnung weitestgehend der Bergordnung von 1339. Das Entstehungsdatum 1326 hielt Joseph von Sperges für falsch, da Herzog Albrecht II. erst 1335 Herzog von Kärnten und Herr der Krain war und datierte sie mit 1336 oder 1346.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German
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    Bergordnung für die Bergwerke außerhalb der Pflege Freibergs 1466 (2022)
    Details
    Publication Date: 2022-06-09
    Description: Bergordnung für die Bergwerke außerhalb der Pflege Freibergs von Kurfürst Ernst und Herzog Albrecht von Sachsen vom 14. April 1466. In sechs Artikeln wurden in dieser Bergordnung die Rechte und Pflichten des Bergmeisters, des Bergschreibers und des Zehntners festgelegt, sowie das Anrecht der Landesherren auf den Zehnten von unedlen Metallen manifestiert.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German
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    Bergbrief Schladming 1408 (2022)
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    Publication Date: 2022-06-09
    Description: Diese als Bergbrief bekannt gewordene Bergordnung wurde von dem Markt- und Stadtrichter Leonhard Egkzlhaim auf Wunsch der Einwohner und Bergleute von Schladming verfasst und am 23. Juli 1408 veröffentlicht. In 18 Artikeln wurden Teile des bereits geltenden Bergrechts aufgeführt und weiterhin auf geltendes altes Recht verwiesen.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German
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    Tracing southern Gondwanan sedimentary paths: A case study of northern Namibian late Palaeozoic sedimentary rocks (2022)
    Details
    Publication Date: 2022-06-17
    Description: The northern Namibian Karoo‐aged successions are part of a Gondwana‐wide sedimentary system emerging at the Carboniferous–Permian boundary and existing for more than 50 Ma. The Karoo Supergroup sedimentary successions are of importance in understanding the evolution of the Karoo rift system. This study presents new whole‐rock geochemical data combined with detrital zircon morphology as well as U−Pb ages and Lu−Hf composition of late Palaeozoic siliciclastic rocks of the Namibian Huab Basin and Kunene area (south‐west Africa). Inferred by youngest detrital zircon U−Pb ages the Verbrande Berg Formation (lower Ecca Group) yields a Sakmarian to Asselian maximum depositional age, whereas the overlying Tsarabis Formation yields an Artinskian maximum depositional age. These ages coincide with the end of the Dwyka ice age and an overall warming and a contemporaneous evolution of the Karoo I rift system across southern Gondwana. The zircon age distribution of the investigated samples yields clusters ranging between ca 500 to 650 Ma (Cambrian–late Neoproterozoic), ca 950 to 1200 Ma (early Neoproterozoic–Mesoproterozoic) and ca 1800 to 1900 Ma (Palaeoproterozoic). Their rounded shapes characterize the zircon grains of the Kunene area and the lower Huab Basin section, whereas upper Huab Basin strata yield mostly unrounded grains. The rounded nature of zircon grains with a diverse U−Pb age spectrum putatively points towards sediment homogenization and multiple recycling stages during the deposition of the sediments and large catchment areas of the depositing rivers. As suggested by zircon grains with a low roundness value and a single Palaeoproterozoic age cluster, the upper Huab Basin successions were probably deposited under drier climatic conditions, small catchment areas and limited sedimentary homogenization. Therefore, the southern Gondwana sedimentary transport and homogenization system may change over time and is dependent on the climate prevailing during deposition. This study shows that the laws of detrital zircon are very complex and are yet to be explored.
    Description: Senckenberg Gesellschaft Fur Naturforschung
    Keywords: ddc:551.701 ; ddc:556
    Language: English
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    Growth of microaerophilic Fe(II)‐oxidizing bacteria using Fe(II) produced by Fe(III) photoreduction (2022)
    Details
    Publication Date: 2022-06-17
    Description: Iron(II) (Fe(II)) can be formed by abiotic Fe(III) photoreduction, particularly when Fe(III) is organically complexed. Light‐influenced environments often overlap or even coincide with oxic or microoxic geochemical conditions, for example, in sediments. So far, it is unknown whether microaerophilic Fe(II)‐oxidizing bacteria are able to use the Fe(II) produced by Fe(III) photoreduction as electron donor. Here, we present an adaption of the established agar‐stabilized gradient tube approach in comparison with liquid cultures for the cultivation of microaerophilic Fe(II)‐oxidizing microorganisms by using a ferrihydrite‐citrate mixture undergoing Fe(III) photoreduction as Fe(II) source. We quantified oxygen and Fe(II) gradients with amperometric and voltammetric microelectrodes and evaluated microbial growth by qPCR of 16S rRNA genes. We showed that gradients of dissolved Fe(II) (maximum Fe(II) concentration of 1.25 mM) formed in the gradient tubes when incubated in blue or UV light (400–530 nm or 350–400 nm). Various microaerophilic Fe(II)‐oxidizing bacteria (Curvibacter sp. and Gallionella sp.) grew by oxidizing Fe(II) that was produced in situ by Fe(III) photoreduction. Best growth for these species, based on highest gene copy numbers, was observed in incubations using UV light in both liquid culture and gradient tubes containing 8 mM ferrihydrite‐citrate mixtures (1:1), due to continuous light‐induced Fe(II) formation. Microaerophilic Fe(II)‐oxidizing bacteria contributed up to 40% to the overall Fe(II) oxidation within 24 h of incubation in UV light. Our results highlight the potential importance of Fe(III) photoreduction as a source of Fe(II) for Fe(II)‐oxidizing bacteria by providing Fe(II) in illuminated environments, even under microoxic conditions.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Ministerium für Wissenschaft, Forschung und Kunst Baden‐Württemberg http://dx.doi.org/10.13039/501100003542
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:579.317 ; ddc:551.9
    Language: English
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    Simulated Future Trends in Marine Nitrogen Fixation Are Sensitive to Model Iron Implementation (2022)
    Details
    Publication Date: 2022-06-17
    Description: Biological nitrogen fixation is an important oceanic nitrogen source, potentially stabilizing marine fertility in an increasingly stratified and nutrient‐depleted ocean. Iron limitation of low latitude primary producers has been previously demonstrated to affect simulated regional ecosystem responses to climate warming or nitrogen cycle perturbation. Here we use three biogeochemical models that vary in their representation of the iron cycle to estimate change in the marine nitrogen cycle under a high CO2 emissions future scenario (RCP8.5). The first model neglects explicit iron effects on biology (NoFe), the second utilizes prescribed, seasonally cyclic iron concentrations and associated limitation factors (FeMask), and the third contains a fully dynamic iron cycle (FeDyn). Models were calibrated using observed fields to produce near‐equivalent nutrient and oxygen fits, with productivity ranging from 49 to 75 Pg C yr−1. Global marine nitrogen fixation increases by 71.1% with respect to the preindustrial value by the year 2100 in NoFe, while it remains stable (0.7% decrease in FeMask and 0.3% increase in FeDyn) in explicit iron models. The mitigation of global nitrogen fixation trend in the models that include a representation of iron originates in the Eastern boundary upwelling zones, where the bottom‐up control of iron limitation reduces export production with warming, which shrinks the oxygen deficient volume, and reduces denitrification. Warming‐induced trends in the oxygen deficient volume in the upwelling zones have a cascading effect on the global nitrogen cycle, just as they have previously been shown to affect tropical net primary production.
    Description: Plain Language Summary: Phytoplankton need nutrients to grow. Two of those nutrients are nitrogen and iron. Climate change projections suggest that in the future there could be less nitrogen supplied to the surface ocean, which might reduce phytoplankton growth. Less phytoplankton growth could impact a wide range of ocean services, like fishing and fossil carbon draw‐down. However, some phytoplankton have the ability to add “new” nitrogen to the surface ocean directly from the atmosphere. In this study, we explore how this biological fixation of new nitrogen might change into the future using three models. These models differ in how iron is represented, but all do equally well in representing the observed nutrient and oxygen distribution. Biological nitrogen fixation slightly decreases with climate change in the very complex iron model and the moderately complex iron model, but it increases strongly (by more than 70% by the year 2100) in the model that does not include iron effects on biology. Our study addresses the importance of iron models and how they can change our view of how the ocean responds to climate change.
    Description: Key Points: Models performing similarly with respect to global NO3, PO4, and O2 distributions yield diverse responses in marine N2 fixation to warming. Marine N2 fixation trends are sensitive to whether iron limits primary production in upwelling regions, for example, the Eastern Tropical Pacific.
    Description: Helmholtz Research School for Ocean System Science and Technology
    Description: New Zealand Ministry of Business, Innovation and Employment
    Description: https://data.geomar.de/downloads/20.500.12085/673e7de0-20ab-4dd3-afe9-c4bfb00b1faf/
    Keywords: ddc:551.9
    Language: English
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    Estimates of water partitioning in complex urban landscapes with isotope‐aided ecohydrological modelling (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2022-06-17
    Description: Urban green space is increasingly viewed as essential infrastructure to build resilience to climate change by retaining water in the city landscape and balancing ecohydrological partitioning into evapotranspiration for cooling and groundwater recharge. Quantifying how different vegetation types affect water partitioning is essential for future management, but paucity of data and the complex heterogeneity of urban areas make water balance estimates challenging. Here, we provide a preliminary assessment of water partitioning from different sized patches of trees and grass as well as from sealed surfaces. To do this, we used limited field observations together with an advanced, process‐based tracer‐aided ecohydrological model at a meso‐scale (5 km2) in central Berlin, Germany. Transpiration was the dominant green water flux accounting for over 50% of evapotranspiration in the modelled area. Green water fluxes were in general greater from trees compared with grass, but grass in large parks transpired more water compared with grass in small parks that were intensively used for recreation. Interception evaporation was larger for trees compared with grass, but soil water evaporation was greater for grass compared with trees. We also show that evapotranspiration from tree‐covered areas comprise almost 80% of the total evapotranspiration from the whole model domain while making up less than 30% of the surface cover. The results form an important stepping‐stone towards further upscaling over larger areas and highlights the importance of continuous high‐resolution hydrological measurements in the urban landscape, as well as the need for improvements to ecohydrological models to capture important urban processes.
    Description: Berlin University Alliance / Einstein Stiftung Berlin, Climate and Water under Change
    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: Urban Climate Observatory (UCO) Berlin
    Keywords: ddc:551.49
    Language: English
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    Critical Zone Response Times and Water Age Relationships Under Variable Catchment Wetness States: Insights Using a Tracer‐Aided Ecohydrological Model (2022)
    Details
    Publication Date: 2022-06-17
    Description: The dynamic relationships between water flux and storage, together with the associated water ages and speed of hydrological responses (as proxies for velocity and celerity respectively) are fundamental to understanding how catchments react to hydroclimate perturbations, such as floods and droughts. Using results from a calibrated, tracer‐aided ecohydrological model (EcH2O‐iso) we analyzed the dynamics of storage‐flux‐age‐response time (RT) interactions at scales that resolve the internal heterogeneity of these non‐stationary relationships. EcH2O‐iso has previously shown an adequate representation of ecohydrological flux partitioning and storage dynamics (celerity), and water ages (velocity) over 11‐year at Demnitzer Millcreek catchment (DMC, 66 km2), a drought‐sensitive, lowland catchment in Germany. The 11‐year period had marked hydroclimatic contrasts facilitating the evaluation of flux‐storage‐age‐RT dynamics under different wetness anomalies. Our results show that the spatio–temporal variability of soil moisture and ecohydrological partitioning dynamics reflect both land use (especially forest cover) and distinct soil units (i.e., brown earth vs. podzolic soils). Spatial differences in RTs of storage were driven by rapid soil evaporation and transpiration responses to rainfall, which revealed a divergence of transpiration ages from RTs. RTs of groundwater and streamflow were fast (days), but mediation by soil water storage dynamics caused marked separation from water ages (years‐decades) of deeper flow paths. Analysis of RTs and ages revealed a degradation of process representation with coarsening model spatial resolution. This study uses novel analysis of the spatio‐temporal interactions of flux‐storage‐age‐RT from a model to understand the sensitivity and resilience of catchment functionality to hydroclimatic perturbations.
    Description: Key Points: Spatio‐temporal variability of soil storage and ecohydrological partitioning was modulated by vegetation characteristics. Transpiration, groundwater, and streamflow response times were distinct from water ages, with spatial differences driven by vegetation units. Lower model resolution reduced spatial variability and increased the difference of catchment response and water age of fluxes and storages.
    Description: FP7 Ideas: European Research Council (FP7 Ideas) http://dx.doi.org/10.13039/100011199
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: http://bitbucket.igb-berlin.de:7990/users/ech2o/repos/ech2o_iso/browse
    Description: https://doi.org/10.5194/hess-25-2239-2021
    Keywords: ddc:551.49
    Language: English
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    The fluvial architecture of buried floodplain sediments of the Weiße Elster River (Germany) revealed by a novel method combination of drill cores with two‐dimensional and spatially resolved geophysical measurements (2022)
    Details
    Publication Date: 2022-06-17
    Description: The complex and non‐linear fluvial river dynamics are characterized by repeated periods of fluvial erosion and re‐deposition in different parts of the floodplain. Understanding the fluvial architecture (i.e. the three‐dimensional arrangement and genetic interconnectedness of different sediment types) is therefore fundamental to obtain well‐based information about controlling factors. However, investigating the fluvial architecture in buried floodplain deposits without natural exposures is challenging. We studied the fluvial architecture of the middle Weiße Elster floodplain in Central Germany, an extraordinary long‐standing archive of Holocene flooding and landscape changes in sensitive loess‐covered Central European landscapes. We applied a novel systematic approach by coupling two‐dimensional transects of electrical resistivity tomography (ERT) measurements and closely spaced core drillings with spatially resolved measurements of electromagnetic induction (EMI) of larger floodplain areas at three study sites. This allowed for (i) time and cost‐efficient core drillings based on preceding ERT measurements and (ii) spatially scaling up the main elements of the fluvial architecture, such as the distribution of thick silt‐clay overbank deposits and paleochannel patterns from the floodplain transects to larger surrounding areas. We found that fine‐grained sand and silt‐clay overbank deposits overlying basal gravels were deposited during several periods of intensive flooding. Those were separated from each other by periods of reduced flooding, allowing soil formation. However, the overbank deposits were severely laterally eroded before and during each sedimentation period. This was probably linked with pronounced meandering or even braiding of the river. Our preliminary chronological classification suggests that first fine‐grained sedimentation must have occurred during the Early to Middle Holocene, and the last phase of lateral erosion and sedimentation during the Little Ice Age. Our study demonstrates the high archive potential of the buried fluvial sediments of the middle Weiße Elster floodplain and provides a promising time and cost‐effective approach for future studies of buried floodplain sediments.
    Description: We applied a novel time and cost‐efficient systematic approach to study the architecture of buried floodplain sediments of the Weiße Elster River in Germany by coupling two‐dimensional transects of Electrical Resistivity Measurements and closely spaced core drillings with spatially resolved measurements of Electromagnetic Induction of larger floodplain areas. We found that fine‐grained overbank deposits deposited during several periods of intensive flooding were severely laterally eroded before and during each following sedimentation period probably linked with pronounced meandering or even braiding.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.35
    Language: English
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    Analytical Solutions for Gravity Changes Caused by Triaxial Volumetric Sources (2022)
    Details
    Publication Date: 2022-06-17
    Description: Volcanic crises are often associated with magmatic intrusions or the pressurization of magma chambers of various shapes. These volumetric sources deform the country rocks, changing their density, and cause surface uplift. Both the net mass of intruding magmatic fluids and these deformation effects contribute to surface gravity changes. Thus, to estimate the intrusion mass from gravity changes, the deformation effects must be accounted for. We develop analytical solutions and computer codes for the gravity changes caused by triaxial sources of expansion. This establishes coupled solutions for joint inversions of deformation and gravity changes. Such inversions can constrain both the intrusion mass and the deformation source parameters more accurately.
    Description: Plain Language Summary: Volcanic crises are usually associated with magmatic fluids that intrude and deform the host rocks before potentially breaching the Earth's surface. It is important to estimate how much fluid (mass and volume) is on the move. Volume can be determined from the measured surface uplift. Mass can be determined from surface gravity changes. The fluid intrusion increases the mass below the volcano, thereby increasing the gravity and pressurizing the rocks. This dilates parts of the host rock and compresses other parts, changing the rock density and redistributing the rock mass. This causes secondary gravity changes, called deformation‐induced gravity changes. The measured gravity change is always the sum of the mass and deformation‐induced contributions. Here, we develop mathematical equations for the rapid estimation of these deformation‐induced gravity changes caused by arbitrary intrusion shapes. This way we can take the mass contribution apart from the deformation contribution. We show that by using this solution not only the intrusion mass, but also other intrusion parameters, including the volume, depth, and shape can be calculated more accurately.
    Description: Key Points; We develop analytical solutions for gravity changes due to the point Compound Dislocation Model simulating triaxial expansions. Rapid coupled inversions of deformation and gravity changes, accounting for deformation‐induced gravity changes are now possible. For shallow sources, estimation errors in the chamber volume change may lead to large biases in the simulated gravity changes.
    Description: EU Horizon 2020 programme NEWTON‐g project, under the FETOPEN‐ Grant Agreement No.
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://volcanodeformation.com/onewebmedia/pCDMgravity.zip
    Keywords: ddc:551
    Language: English
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    Assessment of the Precision of Spectral Model Turbulence Analysis Techniques Using Direct Numerical Simulation Data (2022)
    Details
    Publication Date: 2022-06-17
    Description: The spectral model turbulence analysis technique is widely used to derive kinetic energy dissipation rates of turbulent structures (ɛ) from different in situ measurements in the Earth's atmosphere. The essence of this method is to fit a model spectrum to measured spectra of velocity or scalar quantity fluctuations and thereby to derive ɛ only from wavenumber dependence of turbulence spectra. Owing to the simplicity of spectral model of Heisenberg (1948), https://doi.org/10.1007/bf01668899 its application dominates in the literature. Making use of direct numerical simulations which are able to resolve turbulence spectra down to the smallest scales in dissipation range, we advance the spectral model technique by quantifying uncertainties for two spectral models, the Heisenberg (1948), https://doi.org/10.1007/bf01668899 and the Tatarskii (1971) model, depending on (a) resolution of measurements, (b) stage of turbulence evolution, (c) model used. We show that the model of Tatarskii (1971) can yield more accurate results and reveals higher sensitivity to the lowest ɛ‐values. This study shows that the spectral model technique can reliably derive ɛ if measured spectra only resolve half‐decade of power change within the viscous (viscous‐convective) subrange. In summary, we give some practical recommendations on how to derive the most precise and detailed turbulence dissipation field from in situ measurements depending on their quality. We also supply program code of the spectral models used in this study in Python, IDL, and Matlab.
    Description: Plain Language Summary: Turbulence plays a central role in most geophysical fluids, but our understanding of it remains limited. Atmospheric turbulence plays roles as diverse as dispersion of pollutants in the boundary layer to strong influences on the thermal and wind fields on global scales from the surface to above 100 km. It also is key to transports in, and the large‐scale circulation and structure of, Earth's oceans. Measurements quantifying turbulence intensities and their environments are key to understanding its many effects but remain challenging. In situ measurements of various quantities enable estimates of turbulence intensities but must be calibrated to be of optimal benefit. This study employs a direct numerical simulation of Kelvin‐Helmholtz instabilities that quantifies the associated turbulence dynamics exactly over the range of scales simulated to evaluate theoretical spectral forms enabling the best estimates of the known turbulence intensities.
    Description: Key Points: Accuracies of spectral model turbulence analysis techniques are evaluated using high‐resolution direct numerical simulation data. The Tatarskii model shows very accurate results if measured spectra resolve the viscous subrange for more than 2 decades. The Heisenberg model yields less accurate results that are almost independent of measurement resolution.
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Description: DOD | USAF | AFMC | Air Force Office of Scientific Research (AFOSR) http://dx.doi.org/10.13039/100000181
    Keywords: ddc:551.51
    Language: English
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    From the Top of Martian Olympus to Deep Craters and Beneath: Mars Radiation Environment Under Different Atmospheric and Regolith Depths (2022)
    Details
    Publication Date: 2022-06-17
    Description: In preparation for future human habitats on Mars, it is important to understand the Martian radiation environment. Mars does not have an intrinsic magnetic field and Galactic cosmic ray (GCR) particles may directly propagate through and interact with its atmosphere before reaching the surface and subsurface of Mars. However, Mars has many high mountains and low‐altitude craters where the atmospheric thickness can be more than 10 times different from one another. We thus consider the influence of the atmospheric depths on the Martian radiation levels including the absorbed dose, dose equivalent and body effective dose rates induced by GCRs at varying heights above and below the Martian surface. The state‐of‐the‐art Atmospheric Radiation Interaction Simulator based on GEometry And Tracking Monte Carlo method has been employed for simulating particle interactions with the Martian atmosphere and terrain. We find that higher surface pressures can effectively reduce the heavy ion contribution to the radiation, especially the biologically weighted radiation quantity. However, enhanced shielding (both by the atmosphere and the subsurface material) can considerably enhance the production of secondary neutrons which contribute significantly to the effective dose. In fact, both neutron flux and effective dose peak at around 30 cm below the surface. This is a critical concern when using the Martian surface material to mitigate radiation risks. Based on the calculated effective dose, we finally estimate some optimized shielding depths, under different surface pressures (corresponding to different altitudes) and various heliospheric modulation conditions. This may serve for designing future Martian habitats.
    Description: Plain Language Summary: Thanks to Earth's magnetic field and atmosphere, high‐energy cosmic particles can be efficiently shielded from causing radiation risks for humans on Earth. However, for crewed space missions, in particular long‐term missions to Mars, space radiation is a major risk for the health of astronauts. Mars does not have an intrinsic global magnetic field and its atmosphere is too thin to effectively shield against radiation. Here, we model the Martian radiation environment induced by omnipresent cosmic rays in Mars's atmosphere and terrain. Given that Mars has many high mountains and low‐altitude craters where the atmospheric thickness can be more than 10 times different from one another, we also consider different model setups with different atmospheric profiles. We find that with more shielding the heavy ion contribution to the radiation is reduced while the neutron contribution is enhanced. For a given threshold of the annual biologically weighted radiation effective dose, for example, 100 mSv, the required regolith depth ranges between about 1 and 1.6 m. At a deep crater where the surface pressure is higher, the needed extra regolith shielding is slightly smaller. Our study may serve for mitigating radiation risks when designing future Martian habitats using natural surface material as shielding protection.
    Description: Key Points: We calculate dose, dose equivalent, and effective dose rates induced by various components of galactic cosmic rays on and below Mars surface. Surface pressure which is related to geographic altitude influences the surface and subsurface radiation level. Subsurface secondary neutrons contribute significantly to the effective dose and are a critical concern for radiation risks on Mars.
    Description: CAS strategic priority program
    Description: National Natural Science Foundation of China (NSFC) http://dx.doi.org/10.13039/501100001809
    Description: CNSA pre‐research Project on Civil Aerospace Technologies
    Description: The Key Research Program of the Chinese Academy of Sciences
    Description: German Aerospace Center (DLR)
    Description: https://et-wiki.physik.uni-kiel.de/atris/atris
    Keywords: ddc:523
    Language: English
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    The Arctic Ocean in CMIP6 Models: Biases and Projected Changes in Temperature and Salinity (2022)
    Details
    Publication Date: 2022-06-17
    Description: We examine the historical evolution and projected changes in the hydrography of the deep basin of the Arctic Ocean in 23 climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6). The comparison between historical simulations and observational climatology shows that the simulated Atlantic Water (AW) layer is too deep and thick in the majority of models, including the multi‐model mean (MMM). Moreover, the halocline is too fresh in the MMM. Overall our findings indicate that there is no obvious improvement in the representation of the Arctic hydrography in CMIP6 compared to CMIP5. The climate change projections reveal that the sub‐Arctic seas are outstanding warming hotspots, causing a strong warming trend in the Arctic AW layer. The MMM temperature increase averaged over the upper 700 m at the end of the 21st century is about 40% and 60% higher in the Arctic Ocean than the global mean in the SSP245 and SSP585 scenarios, respectively. Salinity in the upper few hundred meters is projected to decrease in the Arctic deep basin in the MMM. However, the spread in projected salinity changes is large and the tendency toward stronger halocline in the MMM is not simulated by all the models. The identified biases and projection uncertainties call for a concerted effort for major improvements of coupled climate models.
    Description: Plain Language Summary: Coupled climate models are crucial tools for understanding and projecting climate change, especially for the Arctic where the climate is changing at unprecedented rates. A cold fresh layer of water (aka halocline) has been protecting sea‐ice at the surface from the warm layer of water (aka Atlantic Water layer) which flows underneath and could potentially accelerate sea ice melting from below. Climate change disturbs this vertical structure by changing the temperature and salinity of the Arctic Ocean (in a process known as Atlantification and Pacification) which may lead to additional sea ice basal melting and accelerate sea ice decline. We examined the simulated temperature and salinity in the Arctic Ocean deep basin in state‐of‐the‐art climate model simulations which provided the basis for the IPCC Assessment Report. We found that although there are persistent inaccuracies in the representation of Arctic temperature and salinity, the Arctic Ocean below 100 m is subject to much stronger warming than the average global ocean. On the other hand, the upper Arctic Ocean salinity is projected to decrease, which on average may strengthen the isolation of sea ice from Atlantic Water heat in the Arctic deep basin area.
    Description: Key Points: A too deep and thick Arctic Atlantic Water layer continues to be a major issue in contemporary climate models contributing to the CMIP6. The Arctic Ocean below the halocline is subject to much stronger warming than the global mean during the 21st century. The multi‐model mean upper ocean salinity is projected to decrease in the future but with high uncertainty.
    Description: European union's Horizon 2020 research and innovation programme
    Description: German Helmholtz climate initiative REKLIM
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: https://esgf-data.dkrz.de/projects/esgf-dkrz/
    Description: http://psc.apl.washington.edu/nonwp_projects/PHC/Data3.html
    Keywords: ddc:551
    Language: English
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    The Effect of Land Use Classification on the Gas‐Phase and Particle Composition of the Troposphere: Tree Species Versus Forest Type Information (2022)
    Details
    Publication Date: 2022-06-17
    Description: Relationships between vegetation and air quality are intricate and still not fully understood. For regional air quality assessments, a better understanding of the diverse feedback mechanisms is crucial. The present article investigates the impact of land use data set detailedness on air quality predictions. Therefore, two different land use data sets were applied for simulations with COSMO‐MUSCAT for Germany in May 2014. One data set includes detailed information about tree species while the second one obtains generalized widely applied land use classes including mixed and coniferous forests. Moreover, we examined the role of agricultural NO soil emissions, agricultural biomass density enhancements, and model resolution. For a more comprehensive implementation of the secondary organic aerosol (SOA) formation, the SOA module was extended considering additional biogenic volatile organic compound (BVOC) precursor groups from isoprene, α‐pinene, limonene, and sesquiterpene oxidations. The model studies showed substantial differences in BVOC emission patterns between the two land use data sets. The application of detailed tree species information leads to complex BVOC emission patterns with high emission spots. In contrast, coarser forest information lead to standardized comprehensive emissions which result in 50% higher BVOC emissions. These differences affect both the atmospheric oxidizing potential and the production rates of SOA precursors. Land use induced regional differences (tree species minus forest information) in NOx (±2.5%), ozone (−2.5%), OH (±50%), NO3 radical (+70%) concentrations, and SOA (−60%) mass are modeled. Overall, the simulations demonstrate that detailed land use information, extended organic chemistry treatment, and high spatial resolution are mandatory for air quality assessments.
    Description: Plain Language Summary: Trees are associated with being the lungs of the atmosphere as they filter out harmful substances from the air, they store CO2, and produce oxygen via photosynthesis. Other by‐products of photosynthesis are biogenic volatile organic compounds (BVOCs). BVOCs are chemical substances with a high vapor pressure already at room temperatures, so they quickly evaporate from the leaves into the surrounding air and are responsible for the characteristic forest smell. The amount and composition of BVOC emissions strongly depend on the tree species. Every plant has its own distinct emission properties. The chemical degradation of BVOCs impacts the chemical composition of the troposphere and is connected to ground level ozone production and the formation of secondary organic aerosols (SOA), contributing substantially to particulate matter (PM). On a global scale, standardized BVOC emission information on forest levels are often used, but for regional air quality assessments detailed plant specific information is crucial, but still often lacking. Therefore, two different land use data sets were applied in the present study to investigate the impact of standardized forest versus detailed tree‐species information for Germany in May 2014. The study reveals changes in NOx (±2.5%), ozone (−2.5%), OH (±50%), NO3 radical (+70%), and SOA (−60%) concentrations.
    Description: Key Points: Detail of land use data sets crucial for biogenic volatile organic compound emission strength and composition. Composition and concentration variation of these organic compounds induce changes in regional air quality predictions. Detailed land use information, extended organic matter treatment, and high‐resolution simulations are mandatory for air quality assessments.
    Description: Deutsche Bundesstiftung Umwelt (DBU) http://dx.doi.org/10.13039/100007636
    Description: https://doi.org/10.5281/zenodo.4783106
    Description: http://ebas.nilu.no/
    Keywords: ddc:551.5 ; ddc:551.9
    Language: English
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    Ionospheric Corrections for Satellite Altimetry ‐ Impact on Global Mean Sea Level Trends (2022)
    Details
    Publication Date: 2022-06-16
    Description: Atmospheric delay corrections for satellite altimetry measurements are essential for deriving highly accurate sea surface heights and reliable global mean sea level (GMSL) trend estimates. A commonly used method to correct for ionospheric path delays are the usage of GNSS‐based Global Ionospheric Maps (GIM). The different orbit heights of GNSS and altimeter satellites require an adaption of GIM corrections to account for free electrons in the Earth plasmasphere. This study shows that the widely used scaling approach based on the International Reference Ionosphere (IRI) is not able to accurately scale the GIM models. The impact of neglecting the plasmaspheric part of the atmosphere strongly correlates with the solar activity of about 11 years. This manifests itself as trend errors in global GMSL. For the Jason period (2002–2021) a trend error of 0.17 mm/year can be shown, which is even larger for smaller periods (e.g., 1.0 mm/year for Jason‐1 lifetime). The application of an additional constant scaling factor of 0.886 can reduce the trend differences to below 0.05 mm/year.
    Description: Plain Language Summary: Global mean sea level (GMSL) rise is an important indicator for climate change. To precisely measure this quantity that is only in the order of about 3 mm/year, satellite altimeters are used. Their observations have to be corrected for influences in the Earth atmosphere. This study shows deficiencies in one commonly used correction data set. These corrections, based on observations from the Global Navigation Satellite Systems (GNSS) are not accounting for the higher part of the atmosphere, the plasmasphere. Neglecting this influence derives systematic errors with a 11 years cycle that impacts the estimation of GMSL by up to 1 mm/year, depending on the period under investigation. It is recommended to apply an additional scaling of the available corrections in order to reduce the trend error to below 0.05 mm/year.
    Description: Key Points: Global Ionospheric Map corrections in altimetry Sensor Geophysical Data Records are not fully scaled to account for plasmaspheric electron content. Neglecting the plasmaspheric effect leads to trends of up to 1 mm/year in Global mean sea level estimates. The additional application of a scale factor improves the consistency in trend with respect to dual‐frequency satellite altimetry data.
    Description: https://podaac.jpl.nasa.gov/
    Description: https://www.aviso.altimetry.fr/
    Description: https://openadb.dgfi.tum.de/en/products/vertical-total-electron-content/
    Keywords: ddc:538.767 ; ddc:550
    Language: English
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    Structure determination from unindexed powder data from scratch by a global optimization approach using pattern comparison based on cross‐correlation functions (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2022-06-16
    Description: A method of ab initio crystal structure determination from powder diffraction data for organic and metal–organic compounds, which does not require prior indexing of the powder pattern, has been developed. Only a reasonable molecular geometry is required, needing knowledge of neither unit‐cell parameters nor space group. The structures are solved from scratch by a global fit to the powder data using the new program FIDEL‐GO (`FIt with DEviating Lattice parameters ‐ Global Optimization'). FIDEL‐GO uses a similarity measure based on cross‐correlation functions, which allows the comparison of simulated and experimental powder data even if the unit‐cell parameters deviate strongly. The optimization starts from large sets of random structures in various space groups. The unit‐cell parameters, molecular position and orientation, and selected internal degrees of freedom are fitted simultaneously to the powder pattern. The optimization proceeds in an elaborate multi‐step procedure with built‐in clustering of duplicate structures and iterative adaptation of parameter ranges. The best structures are selected for an automatic Rietveld refinement. Finally, a user‐controlled Rietveld refinement is performed. The procedure aims for the analysis of a wide range of `problematic' powder patterns, in particular powders of low crystallinity. The method can also be used for the clustering and screening of a large number of possible structure candidates and other application scenarios. Examples are presented for structure determination from unindexed powder data of the previously unknown structures of the nanocrystalline phases of 4,11‐difluoro‐, 2,9‐dichloro‐ and 2,9‐dichloro‐6,13‐dihydro‐quinacridone, which were solved from powder patterns with 14–20 peaks only, and of the coordination polymer dichloro‐bis(pyridine‐N)copper(II).
    Description: A new method for the structure determination of molecular crystals from unindexed powder data has been developed and successfully applied. The method performs a global optimization using pattern comparison based on cross‐correlation functions.
    Keywords: ddc:548
    Language: English
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    The effect of formation processes on the frequency of palaeolithic cave sites in semiarid zones: Insights from Kazakhstan (2022)
    Details
    Publication Date: 2022-06-20
    Description: Central Asian caves with Palaeolithic deposits are few, but they provide a rich record of human fossils and cultural assemblages that has been used to model Late Pleistocene hominin dispersals. However, previous research has not yet systematically evaluated the formation processes that influence the frequency of Palaeolithic cave sites in the region. To address this deficiency, we combined field survey and micromorphological analyses in the piedmont zone of south Kazakhstan. Here, we present our preliminary results focusing on selected sites of the Qaratau mountains. Sediment cover varies among the surveyed caves, and loess‐like sediments dominate the cave sequences. The preservation of cave deposits is influenced by reworking of cave sediments within the caves but also by the broader erosional processes that shape semiarid landscapes. Ultimately, deposits of potentially Pleistocene age are scarce. Our study provides new data in the geoarchaeologically neglected region of Central Asia and demonstrates that micromorphology has great analytical potential even within the limitations of rigorous survey projects. We outline some of the processes that influence the formation and preservation of cave deposits in Kazakhstan, as well as broader implications for the distribution of Palaeolithic cave sites in Central Asia and other semiarid environments.
    Description: H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Keywords: ddc:551.447 ; ddc:930.1
    Language: English
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    Bergordnung für den Schreckenberg (2022)
    Details
    Publication Date: 2022-06-14
    Description: Bergordnung für die Bergwerke am Schreckenberg vom 11. Februar 1493. Erstellt wurde sie auf Wunsch von Herzog Georg von Sachsen von den Richtern und Schöffen von Geyer auf der Grundlage der Bergordnung von Glashütte vom 29. Dezember 1490. In 27 Artikeln werden die Regeln zur Verwaltung des beginnenden Bergbaus festgelegt. Als Ort der Verwaltung des Bergbaus wird Geyer bestimmt.
    Description: source
    Keywords: ddc:343.077 ; ddc:622
    Language: German
    Type: doc-type:book , updatedVersion
    Format: 7
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    How close are we to 1.5 degC or 2 degC of global warming? (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2022-08-09
    Keywords: ddc:551.6
    Language: English
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    Effects of the Hydrous Domain in the Mantle Wedge on Magma Formation and Mixing at the Northeast Lau Spreading Center, SW Pacific (2022)
    Details
    Publication Date: 2022-08-09
    Description: Abundant volcanic activity occurs in the back‐arc region of the northern Tofua island arc where the Northeast Lau Spreading Center (NELSC) propagates southwards into older crust causing the formation of numerous seamounts at the propagating rift tip. An off‐axis volcanic diagonal ridge (DR) occurs at the eastern flank of the NELSC, linking the large rear‐arc volcano Niuatahi with the NELSC. New geochemical data from the NELSC, the southern propagator seamounts, and DR reveal that the NELSC lavas are tholeiitic basalts whereas the rear‐arc volcanoes typically erupt lavas with boninitic composition. The sharp geochemical boundary probably reflects the viscosity contrast between off‐axis hydrous harzburgitic mantle and dry fertile mantle beneath the NELSC. The new data do not indicate an inflow of Samoa plume mantle into the NELSC, confirming previously published He isotope data. The NELSC magmas form by mixing of an enriched and a depleted Indian Ocean‐type upper mantle end‐member implying a highly heterogeneous upper mantle composition in this area. Most NELSC lavas are little affected by a slab component implying that melting is adiabatic beneath the spreading center. The DR lavas show the influence of a component from the subducted Louisville Seamount Chain, which was previously thought to be restricted to the nearby arc volcanoes Niuatoputapu and Tafahi. This signature is rarely detected along the NELSC implying little mixing of melts from the low‐viscosity hydrous portion of the mantle wedge beneath the rear‐arc volcanoes into the melting region of the dry mantle beneath the NELSC.
    Description: Plain Language Summary: Volcanic activity is abundant at subduction zones and the chemical analysis of the erupted rocks allows to determine the material transport in the Earth's mantle. The Northeast Lau Spreading Center (NELSC) forms by extension and volcanism behind the northern Tofua island arc. Several large volcanic structures occur east of the NELSC and the lavas of these off‐axis volcanoes are chemically and isotopically distinct implying little mixing with the magmas of the NELSC. The differences suggest decompression melting of relatively dry mantle beneath the NELSC whereas the off‐axis volcanoes reflect melting of water‐rich mantle affected by fluids from the subducting Pacific Plate. The sharp geochemical boundary between the NELSC and off‐axis volcanoes is probably due to a large viscosity contrast between hydrous harzburgitic mantle and dry fertile mantle. Element and isotope ratios indicate that the NELSC magmas form by mixing of enriched and depleted portions of the upper mantle, and we do not find evidence for inflow of the Samoa deep mantle plume from the north. Some of the off‐axis lavas contain a component from a volcanic chain that was subducted some 4 million years ago and that was previously only known in two volcanoes of the Tofua island arc.
    Description: Key Points: Variably enriched mantle sources melt beneath the Northeast Lau Spreading Center (NELSC) but there is no evidence for Samoa mantle plume inflow. Relatively dry fertile mantle beneath NELSC causes sharp geochemical boundary with hydrous harzburgitic North Tonga mantle wedge. Subducted Louisville Seamount Chain material affects rear‐arc volcanism.
    Description: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.21 ; ddc:551.116 ; ddc:551.9
    Language: English
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    Diagnosis of Model Errors With a Sliding Time‐Window Bayesian Analysis (2022)
    Details
    Publication Date: 2022-08-09
    Description: Deterministic hydrological models with uncertain, but inferred‐to‐be‐time‐invariant parameters typically show time‐dependent model errors. Such errors can occur if a hydrological process is active in certain time periods in nature, but is not resolved by the model or by its input. Such missing processes could become visible during calibration as time‐dependent best‐fit values of model parameters. We propose a formal time‐windowed Bayesian analysis to diagnose this type of model error, formalizing the question “In which period of the calibration time‐series does the model statistically disqualify itself as quasi‐true?” Using Bayesian model evidence (BME) as model performance metric, we determine how much the data in time windows of the calibration time‐series support or refute the model. Then, we track BME over sliding time windows to obtain a dynamic, time‐windowed BME (tBME) and search for sudden decreases that indicate an onset of model error. tBME also allows us to perform a formal, sliding likelihood‐ratio test of the model against the data. Our proposed approach is designed to detect error occurrence on various temporal scales, which is especially useful in hydrological modeling. We illustrate this by applying our proposed method to soil moisture modeling. We test tBME as model error indicator on several synthetic and real‐world test cases that we designed to vary in error sources (structure and input) and error time scales. Results prove the successful detection errors in dynamic models. Moreover, the time sequence of posterior parameter distributions helps to investigate the reasons for model error and provide guidance for model improvement.
    Description: Key Points: We propose a data‐driven method for model‐structural error detection. Our method rests on a statistically rigorous Bayesian framework without prior assumptions about error sources or patterns. We confirm successful error detection on various temporal scales in synthetic test cases and present insights from a real‐world case study.
    Description: German Research Foundation (DFG)
    Description: Cluster of Excellence
    Description: University of Stuttgart
    Description: https://doi.org/10.18419/darus-1836
    Keywords: ddc:550.285
    Language: English
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    Highly resolved modeling of extreme wind speed in North America and Europe (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2022-08-09
    Description: High wind speed (U) is one of the most dangerous natural hazards in North America and Europe. As a result, spatially explicit, statistical estimation of extreme U is of particular relevance for many sectors. However, the most common sources of wind speed data such as reanalysis data and in situ measurements are limited for this purpose due to their coarse spatial resolution and low representativeness. Thus, the main goal was to develop a high spatial resolution (250 m × 250 m) model (GloWiSMo‐X) for monthly mapping of the maximum hourly U for a 10‐year return period (U10yr) in North America and Europe. The multistep development of GloWiSMo‐X is based on 2544 hourly U time series available from the integrated surface global hourly meteorological data set (UNCEI), U time series from ERA5 (UERA5), and mean wind speed from the Global Wind Speed Model (U¯GloWiSMo). Firstly, the block maxima method was applied to estimate monthly wind speed for a 10‐year return period for both UNCEI (U10yr,NCEI) and UERA5 (U10yr,ERA5). Secondly, the least squares boosting approach was used to predict the target variable U10yr,NCEI yielding the predictions Û10yr. The predictor variables U10yr,ERA5, U¯GloWiSMo, continent, and month were used as input. It was found that the highest monthly continental means of Û10yr (U¯10yr) in January are 16.4 m/s in North America and 16.3 m/s in Europe. U¯10yr dropped to 13.4 m/s and 12.5 m/s in August. The annual cycle of U¯10yr is more pronounced in Europe than in North America. The central parts of the USA and Western Europe were identified as intracontinental regions with the highest U¯10yr. GloWiSMo‐X proves to be very broadly applicable as it covers two different continents and all months. The model validation by the mean squared error (MSE) demonstrates its improved predictive power compared to ERA5.
    Description: A high spatial resolution (250 m × 250 m) model (GloWiSMo‐X) for monthly mapping of the maximum hourly wind speed for a 10‐year return period in North America and Europe was developed. The highest monthly continental means are 16.4 m/s in North America and 16.3 m/s in Europe. Due to the pronounced annual cycle, it drops to 13.4 m/s and 12.5 m/s in August. image
    Description: Bundesministerium für Umwelt, Naturschutz und nukleare Sicherheit
    Keywords: ddc:551.5
    Language: English
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