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  • 2020-2024  (7,860)
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  • 1
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    Bergordnung Herzog Georg für Altenberg und Geising (2023)
    Details
    Publication Date: 2023-01-05
    Description: Nachdem sich Herzog Georg von Sachsen mit den Problemen des Bergbaus auf dem Aldenberg und Geising auseinandergesetzt hatte, erlies er am 11. November 1489 eine Ordnung für die dortigen Bergwerke. In den acht Artikeln dieser Ordnung wurden die Entlohnung der Bergleute sowie die Pflichten der Hutleute, Mühlmeister, Schmelzer und die Strafen bei Zuwiderhandlung festgelegt. Weiterhin wurde eine Vereidigung der Hutleute, Mühlenmeister und Schmelzer befohlen.
    Description: source
    Keywords: Herzog Georg von Sachsen ; Herzog Albrecht von Sachsen ; Hans von Bärenstein zu Ottendorf ; Altenberg ; Geising ; Zinnbergbau ; Sachsen ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
    Format: 6
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  • 2
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    Bergordnung Herzog Siegmund von Österreich für Schwaz (2022)
    Details
    Publication Date: 2023-01-02
    Description: Diese Bergordnung wurde am 26. Juli 1449 für die Bergwerke in Schwaz von Herzog Siegmund von Österreich, Steiermark und Kärnten sowie Herr zu Krain und Pfirt, Graf zu Tirol und Kyburg, Landgraf zu Elsaß und Markgraf zu Burgau erlassen. Grundlage war ein 38 Paragrafen umfassendes Gutachten das von Herzog Siegmund mit einer zwölf Paragrafen umfassenden Bestätigung als Bergordnung in Kraft gesetzt wurde. Erklärt wurden das Gerichtswesen, die Holzrechte, die Entlohnung und Versorgung der im Bergbau Beschäftigten sowie die Rechte und Pflichten der Markscheider.
    Description: source
    Keywords: Herzog Siegmund von Österreich ; Österreich ; Steiermark ; Kärnten ; Tirol ; Elsaß ; Gossensaß ; Meran ; Schwaz ; Freundsberg, Burg ; Arlberg ; Brenner ; Silberbergbau ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
    Format: 13
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  • 3
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    Plasmoids in the Jovian Magnetotail: Statistical Survey of Ion Acceleration Using Juno Observations (2022)
    Details
    Publication Date: 2023-01-12
    Description: Transient magnetic reconnection plays an important role in energetic particle acceleration in planetary magnetospheres. Jupiter's magnetosphere provides a unique natural laboratory to study processes of energy transport and transformation. Strong electric fields in spatially confined structures such as plasmoids can be responsible for ion acceleration to high energies. In this study we focus on the effectiveness of ion energization and acceleration in plasmoids. Therefore, we present a statistical study of plasmoid structures in the predawn magnetotail, which were identified in the magnetometer data of the Juno spacecraft from 2016 to 2018. We additionally use the energetic particle observations from the Jupiter Energetic Particle Detector Instrument which discriminates between different ion species. We are particularly interested in the analysis of the acceleration and energization of oxygen, sulfur, helium, and hydrogen ions. We investigate how the event properties, such as the radial distance and the local time of the observed plasmoids in the magnetotail, affect the ion intensities close to the current sheet center. Furthermore, we analyze if ion acceleration is influenced by magnetic field turbulence inside the plasmoids. We find significant heavy ion acceleration in plasmoids close to the current sheet center which is in line with the previous statistical results based on Galileo observations conducted by Kronberg et al. (2019, https://doi.org/10.1029/2019JA026553). The observed effectiveness of the acceleration is dependent on the position of Juno in the magnetotail during the plasmoid event observation. Our results show no correlation between magnetic field turbulence and nonadiabatic acceleration for heavy ions during plasmoids.
    Description: Key Points: Intensity of heavy ions is strongly increased during plasmoids close to the current sheet center. Significant increase of heavy ion intensities is observed in plasmoids with larger wave power. Acceleration of heavy and light ions in plasmoids due to resonant interaction with the magnetic field fluctuations could not be observed.
    Description: Volkswagen Foundation (VolkswagenStiftung) http://dx.doi.org/10.13039/501100001663
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: NASA
    Description: https://pds-ppi.igpp.ucla.edu/
    Keywords: ddc:523 ; plasmoids ; Juno ; JEDI ; ion acceleration
    Language: English
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  • 4
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    Moderate and Severe Hydrological Droughts in Europe Differ in Their Hydrometeorological Drivers (2022)
    Details
    Publication Date: 2023-01-12
    Description: Hydrological extreme events are generated by different sequences of hydrometeorological drivers, the importance of which may vary within the sample of drought events. Here, we investigate how the importance of different hydrometeorological driver sequences varies by event magnitude using a large sample of catchments in Europe. To do so, we develop an automated classification scheme for streamflow drought events. The classification scheme standardizes a previous qualitative drought typology and assigns events to one of eight drought event types—each characterized by a set of single or compounding drivers—using information about seasonality, precipitation deficits, and snow availability. The objective event classification reveals how drought drivers vary not just in space and by season, but also with event magnitude. Specifically, we show that (a) rainfall deficit droughts and cold snow season droughts are the dominant drought event type in Western Europe and Eastern and Northern Europe, respectively; (b) rainfall deficit and cold snow season droughts are important from autumn to spring while snowmelt and wet‐to‐dry season droughts are important in summer; and (c) moderate droughts are mainly driven by rainfall deficits while severe events are mainly driven by snowmelt deficits in colder climates and by streamflow deficits transitioning from the wet to the dry season in warmer climates. These differences in sequences of drought generation mechanisms for severe and moderate events suggest that future changes in hydrometeorological drivers may affect moderate and severe events differently.
    Description: Key Points: We develop a standardized and objective classification scheme for streamflow droughts using hydroclimatic information. The most severe drought events are governed by other processes than moderate events. Moderate droughts are dominated by rainfall deficits and severe droughts by snowmelt deficits or prolonged rainfall deficit droughts.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: EC/H2020/PRIORITY 'Excellent science'/H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: https://www.bafg.de/GRDC/EN/02_srvcs/21_tmsrs/riverdischarge_node.html
    Description: https://doi.pangaea.de/10.1594/PANGAEA.887470
    Description: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-land?tab=overview
    Description: http://www.hydroshare.org/resource/77114d4dfdfd4dd39e0e1d99165f27b3
    Keywords: ddc:551.6 ; drought types ; drought generation ; extremes ; typology ; classification ; streamflow
    Language: English
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  • 5
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    Groundwater Responses to Earth Tides: Evaluation of Analytical Solutions Using Numerical Simulation (2022)
    Details
    Publication Date: 2023-01-12
    Description: Harmonic Earth tide components in well water levels have been used to estimate hydraulic and geomechanical subsurface properties. However, the robustness of various methods based on analytical solutions has not been established. First, we review the theory and examine the latest analytical solution used to relate well water levels to Earth tides. Second, we develop and verify a novel numerical model coupling hydraulics and geomechanics to Earth tide strains. Third, we assess subsurface conditions over depth for a range of realistic properties. Fourth, we simulate the well water level response to Earth tide strains within a 2D poroelastic layered aquifer system confined by a 100 m thick aquitard. We find that the non‐linear inversion of analytical solutions to match two observations (amplitudes and phases) to multiple unknown parameters is sensible to the initial guess. We reveal that undrained, confined conditions are necessary for the analytical solution to be valid. This occurs for the dominant M2 frequency at depths 〉50 m and requires specific storage at constant strain of Sϵ ≥ 10−6 m−1, hydraulic conductivity of the aquitard of kl ≤ 5 ⋅ 10−5 ms−1 and aquifer of ka ≥ 10−4 ms−1. We further illustrate that the analytical solution is valid in unconsolidated systems, whereas consolidated systems require additional consideration of the Biot modulus. Overall, a priori knowledge of the subsurface system supports interpretation of the groundwater response. Our results improve understanding of the effect of Earth tides on groundwater systems and its interpretation for subsurface properties.
    Description: Plain Language Summary: Earth tide induced strains in the subsurface lead to well water level fluctuations in groundwater monitoring wells. This groundwater response has been interpreted with analytical solutions to estimate aquifer properties. However, analytical solutions are based on simplified assumptions whose accuracy have not yet been tested. We develop a new approach to simulate the influence of Earth tides on groundwater based on fundamental physical principles. We simulate realistic conditions and compare our results to those from analytical solution to determine the hydraulic and subsurface conditions under which simplified interpretations are valid. Our results improve understanding of the effects of Earth tides on groundwater systems and interpretation of subsurface properties from well water levels.
    Description: Key Points: We develop and verify a numerical model for the well water level response to Earth tides. Subsurface property estimation requires undrained and confined conditions occurring at depths 〉50 m. Amplitudes and phases from numerical and analytical solutions systematically diverge reflecting theory simplifications.
    Description: German Research Council
    Description: https://doi.org/10.5281/zenodo.6950492
    Keywords: ddc:551 ; tidal subsurface analysis ; numerical modeling ; Earth tides
    Language: English
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  • 6
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    Geowissenschaftliche Mitteilungen - GMIT 90 (2022)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2023-01-09
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2022 enthält die Themenblöcke: GEOfokus: Klimagerechte Geowissenschaften Glaubwürdigkeit und Vorbild, 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 ; GMIT
    Language: German
    Type: doc-type:book , publishedVersion
    Format: 132
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  • 7
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    Kompensation des Schutzguts Boden in Planungs- und Genehmigungsverfahren (2022)
    Landesamt für Geologie und Bergbau Rheinland-Pfalz
    Details
    Publication Date: 2023-01-10
    Description: manual
    Keywords: ddc:631.4 ; Rheinland-Pfalz ; Hessen ; Bodenschutz ; Raumplanung
    Language: German
    Type: doc-type:book , publishedVersion
    Format: 68
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  • 8
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    Digitization of imaging plates from Guinier powder X‐ray diffraction cameras (2022)
    Nasir, Jamal ; Steinbrück, Nils ; Xu, Ke ; [et al.]
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-01-15
    Description: A Guinier camera equipped with an imaging plate is used to investigate and eliminate the sources of instrumental errors affecting the quality of the obtained scanned Guinier data. A program with a graphical user interface is presented which converts the data of the scanned images into different standard file formats for powder X‐ray patterns containing intensities, their standard deviations and the diffraction angles. The program also allows for manual and automatic correction of the 2gθ scale against a known reference material. It is shown using LaB6 that the exported X‐ray diffraction patterns provide a 2gθ scale reproducible enough to allow for averaging diffractograms obtained from different exposures of the imaging plate for the same sample. As shown on a mixture of NaCl and sodalite, the quality of the produced data is sufficient for Rietveld refinement. The software including source code is made available under a free software license.
    Description: A program for the digitization of Guinier powder diffraction images is described, which works with images from both optical and laser scanners. Thus, processing of data from storage‐phosphor‐based imaging plates and Ag‐based photographic films is possible.
    Keywords: ddc:548 ; IPreader software ; Guinier cameras ; imaging plates (IPs) ; diffraction pattern conversion into data columns ; powder X‐ray diffraction ; data processing ; Guinier method
    Language: English
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  • 9
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    Martian Atmospheric Spectral End‐Members Retrieval From ExoMars Thermal Infrared (TIRVIM) Data (2022)
    Details
    Publication Date: 2023-01-15
    Description: Key knowledge about planetary composition can be recovered from the study of thermal infrared spectral range datasets. This range has a huge diagnostic potential because it contains diagnostic absorptions from a planetary surface and atmosphere. The main goal of this study is to process and interpret the dataset from the Thermal Infrared channel (TIRVIM) which is part of the Atmospheric Chemistry Suite of the ExoMars2016 Trace Gas Orbiter mission to find and characterize dust and water ice clouds in the atmosphere. The method employed here is based on the application of principal component analysis and target transformation techniques to extract the independent variable components present in the analyzed dataset. Spectral shapes of both atmospheric dust and water ice aerosols have been recovered from the analysis of TIRVIM data. The comparison between our results with those previously obtained on Thermal Emission Spectrometer (TES) data and with previous analysis on TIRVIM data, validates the methodology here applied, showing that it allows to correctly recover the atmospheric spectral endmembers present in the TIRVIM data. Moreover, comparison with atmospheric retrievals on PFS, TES and IRIS data, allowed us to assess the temporal stability and homogeneity of dust and water ice components in the Martian atmosphere over a time period of almost 50 years.
    Description: Plain Language Summary: The analysis of thermal infrared datasets from planetary bodies is of key importance for the understanding of a planet's climate evolution and history: it contains valuable information about composition, temperature and state of the atmosphere. Moreover, surface properties and the surface‐atmosphere interaction can be studied. Here we investigated new thermal infrared data from the Thermal Infrared channel instrument of the ExoMars Trace Gas Orbiter with the main goal of carefully identifying Martian atmospheric dust and water ice clouds components. A methodology based on principal component and target transformation factor analysis techniques has been applied. Based on our results, this methodology can correctly recover both atmospheric dust and water ice aerosols spectral shapes and their abundances in the Martian atmosphere.
    Description: Key Points: First successful application of principal components and target transformation techniques to high‐resolution Thermal Infrared channel (TIRVIM) data. Spectral shapes of both atmospheric dust and water ice clouds are recognized and recovered. TIRVIM data are successfully modeled through a linear combination of the recovered water ice and dust end‐members.
    Description: Roscosmos and ESA
    Description: https://doi.org/10.5281/zenodo.7032738
    Keywords: ddc:523 ; Martian atmosphere ; TIRVIM data
    Language: English
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  • 10
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    Measuring zero water level in stream reaches: A comparison of an image‐based versus a conventional method (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-15
    Description: A limited number of gauging stations, especially for nested catchments, hampers a process understanding of the interaction between streamflow, groundwater and water usage during drought. Non‐commercial measurement devices can help overcome this lack of monitoring, but they need to be thoroughly tested. The Dreisam River in the South‐West of Germany was affected by several hydrological drought events from 2015 to 2020 during which parts of the main stream and tributaries fell dry. Therefore it provided a useful case study area for a flexible longitudinal water quality and quantity monitoring network. Among other measurements the setup employs an image‐based method with QR codes as fiducial marker. In order to assess under which conditions the QR‐code based water level loggers (WLL) deliver data according to scientific standards, we compared its performance to conventional capacitive based WLL. The results from 20 monitoring stations reveal that the riverbed was dry for 〉50% at several locations and even for 〉70% at most severely affected locations during July and August 2020, with the north western parts of the catchment being especially concerned. Highly variable longitudinal drying patterns of the stream reaches emerged from the monitoring. The image‐based method was found valuable for identification and validation of zero level occurrences. Nevertheless, a simple image processing approach (based on an automatic thresholding algorithm) did not compensate for errors due to natural conditions and technical setup. Our findings highlight that the complexity of measurement environments is a major challenge when working with image‐based methods.
    Description: We monitored zero water levels in a meso‐scale catchment with temperate climate by means of image‐based and conventional water level logging techniques. A detailed analysis of the longitudinal drying patterns enables a discussion about hydrological connectivity and the processes influencing the drying.
    Description: Badenova Fund For Innovation
    Description: https://doi.org/10.6094/UNIFR/228702
    Keywords: ddc:551.48 ; hydrological drought ; innovative sensors ; longitudinal connectivity ; stream reaches ; streamflow intermittency ; zero flow
    Language: English
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  • 11
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    Present‐Day Upper‐Mantle Architecture of the Alps: Insights From Data‐Driven Dynamic Modeling (2022)
    Details
    Publication Date: 2023-01-15
    Description: The dynamics of the Alps and surrounding regions is still not completely understood, partly because of a non‐unique interpretation of its upper‐mantle architecture. In particular, it is unclear if interpreted slabs are consistent with the observed surface deformation and topography. We derive three end‐member scenarios of lithospheric thickness and slab geometries by clustering available shear‐wave tomography models into a statistical ensemble. We use these scenarios as input for geodynamic simulations and compare modeled topography, surface velocities and mantle flow to observations. We found that a slab detached beneath the Alps, but attached beneath the Northern Apennines captures first‐order patterns in topography and vertical surface velocities and can provide a causative explanation for the observed seismicity.
    Description: Plain Language Summary: Present‐day surface deformation, including earthquakes, plate motion, and mass (re)distribution, results from processes operating at the surface and in the interior of the Earth. Understanding these processes and their coupling is of utmost importance in light of the hazard they pose to society. The Alps provide an excellent natural laboratory to understand such coupling. Here, we use seismic tomography models to constrain its upper‐mantle architecture. We further use these models to quantify forces originating from the resolved architecture and their effects on the present‐day surface deformation. The models can reproduce first‐order patterns in the observed topography and vertical surface motions. We found a causative correlation between the presence of a shallow slab attached to the overlying lithosphere in the Northern Apennines and the seismicity in the region. Our results allow us to better understand the transfer of internal forces to the surface, thereby helping to quantify the present‐day mechanical setup of the area.
    Description: Key Points: Statistical ensemble of S‐wave tomography models is used to infer the Lithosphere‐Asthenosphere Boundary configuration and slab geometries in the Alps. The 3‐D upper‐mantle architecture from the statistics reproduce first‐order patterns in observed topography and Global Navigation Satellite Systems vertical velocities. A shallow/attached slab in the Northern Apennines is consistent with the mantle depth seismicity observed in this region.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5880/GFZ.4.5.2019.004
    Description: https://gfzpublic.gfz-potsdam.de/pubman/item/item_238001
    Description: http://ds.iris.edu/ds/products/emc-earthmodels/
    Description: https://doi.org/10.5281/zenodo.7071571
    Description: https://doi.org/10.5281/zenodo.6538257
    Keywords: ddc:551.1 ; Alps ; Apennines ; lithospheric architecture ; slabs ; seismicity
    Language: English
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  • 12
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    Cold‐water coral ecosystems under future ocean change: Live coral performance vs. framework dissolution and bioerosion (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-15
    Description: Physiological sensitivity of cold‐water corals to ocean change is far less understood than of tropical corals and very little is known about the impacts of ocean acidification and warming on degradative processes of dead coral framework. In a 13‐month laboratory experiment, we examined the interactive effects of gradually increasing temperature and pCO2 levels on survival, growth, and respiration of two prominent color morphotypes (colormorphs) of the framework‐forming cold‐water coral Lophelia pertusa, as well as bioerosion and dissolution of dead framework. Calcification rates tended to increase with warming, showing temperature optima at ~ 14°C (white colormorph) and 10–12°C (orange colormorph) and decreased with increasing pCO2. Net dissolution occurred at aragonite undersaturation (ΩAr 〈 1) at ~ 1000 μatm pCO2. Under combined warming and acidification, the negative effects of acidification on growth were initially mitigated, but at ~ 1600 μatm dissolution prevailed. Respiration rates increased with warming, more strongly in orange corals, while acidification slightly suppressed respiration. Calcification and respiration rates as well as polyp mortality were consistently higher in orange corals. Mortality increased considerably at 14–15°C in both colormorphs. Bioerosion/dissolution of dead framework was not affected by warming alone but was significantly enhanced by acidification. While live corals may cope with intermediate levels of elevated pCO2 and temperature, long‐term impacts beyond levels projected for the end of this century will likely lead to skeletal dissolution and increased mortality. Our findings further suggest that acidification causes accelerated degradation of dead framework even at aragonite saturated conditions, which will eventually compromise the structural integrity of cold‐water coral reefs.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Marine Research in Ireland
    Description: French National Research Agency http://dx.doi.org/10.13039/501100001665
    Keywords: ddc:577.7 ; cold-water corals ; ocean change ; laboratory experiments ; framwork dissolution ; bioerosion
    Language: English
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  • 13
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    A Decentralized Approach for Modeling Organized Convection Based on Thermal Populations on Microgrids (2022)
    Details
    Publication Date: 2023-01-17
    Description: In this study, a spectral model for convective transport is coupled to a thermal population model on a two‐dimensional horizontal “microgrid,” covering the typical gridbox size of general circulation models. The goal is to explore new ways of representing impacts of spatial organization in cumulus cloud fields. The thermals are considered the smallest building block of convection, with thermal life cycle and movement represented through binomial functions. Thermals interact through two simple rules, reflecting pulsating growth and environmental deformation. Long‐lived thermal clusters thus form on the microgrid, exhibiting scale growth and spacing that represent simple forms of spatial organization and memory. Size distributions of cluster number are diagnosed from the microgrid through an online clustering algorithm, and provided as input to a spectral multiplume eddy‐diffusivity mass flux scheme. This yields a decentralized transport system, in that the thermal clusters acting as independent but interacting nodes that carry information about spatial structure. The main objectives of this study are (a) to seek proof of concept of this approach, and (b) to gain insight into impacts of spatial organization on convective transport. Single‐column model experiments demonstrate satisfactory skill in reproducing two observed cases of continental shallow convection. Metrics expressing self‐organization and spatial organization match well with large‐eddy simulation results. We find that in this coupled system, spatial organization impacts convective transport primarily through the scale break in the size distribution of cluster number. The rooting of saturated plumes in the subcloud mixed layer plays a key role in this process.
    Description: Plain Language Summary: Recent studies have emphasized the importance of the spatial structure of convective cloud fields in Earth's climate, yet this phenomenon is not yet represented well in Earth System Models (ESMs). This study explores a new way to achieve this goal, by considering spatial organization at the scale of small bubbles of rising air called thermals that together make up convective clouds. Populations of interacting thermals are modeled in a computationally efficient way on a small two‐dimensional grid. This microgrid is then coupled to a convection scheme, which stands for the set of equations used to statistically represent the impact of convective transport at scales that remain unresolved in ESMs. The coupling makes the scheme decentralized, in that the transport becomes dependent on a population of longer‐lived convective structures that slowly develop and evolve on the microgrid. The new scheme is tested for observed conditions at a meteorological site in the Southern Great Plains area of the United States, making use of a combination of high‐resolution simulations and measurements to evaluate performance. Apart from proof of concept for the new modeling approach, the results provide new insights into how the spatial structure of convective cloud populations can affect its vertical transport.
    Description: Key Points: A multiplume spectral convection scheme is coupled to a binomial thermal population model on a horizontal microgrid. Observed diurnal cycles of continental shallow convection are reproduced, including good agreement on scale growth and spatial organization. Spatial organization impacts convective transport through the scale break in the cluster number density, with a key role played by plume rooting.
    Description: U.S. Department of Energy http://dx.doi.org/10.13039/100000015
    Description: https://doi.org/10.5281/zenodo.6044338
    Keywords: ddc:551.5 ; convective parameterization ; spatial organization ; population dynamics ; thermals ; microgrid modeling ; shallow cumulus
    Language: English
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  • 14
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    On the Resolution of Triangular Meshes (2022)
    Details
    Publication Date: 2023-01-17
    Description: It is generally agreed that the resolution of a regular quadrilateral mesh is the side length of quadrilateral cells. There is less agreement on the resolution of triangular meshes, exacerbated by the fact that the numbers of edges or cells on triangular meshes are approximately three or two times larger than that of vertices. However, the geometrical resolution of triangular meshes, that is, maximum wavenumbers or smallest wavelengths that can be represented on such meshes, is a well defined quantity, known from solid state physics. These wavenumbers are related to a smallest common mesh cell (primitive unit cell), and the set of mesh translations that map it into itself. They do not depend on whether discrete degrees of freedom are placed on vertices, cells or edges. For equilateral triangles the smallest wavelength equals twice the triangle height. Resolutions of quadrilateral and triangular meshes approximately agree if they have the same numbers of vertices.
    Description: Plain Language Summary: Some models used in climate studies are formulated on triangular computational meshes. We discuss how to determine the smallest scales that are resolved on such meshes. They are referred to as a mesh resolution. The notion of mesh resolution is commonly used to relate climate model results simulated on different meshes.
    Description: Key Points: Geometrical resolution of an equilateral triangular mesh is defined by the height of its triangles. Quadrilateral and triangular meshes with the same number of vertices have approximately the same resolution.
    Description: Collaborative Research Centre
    Description: German Research Foundation
    Keywords: ddc:550 ; triangular meshes ; resolved wavenumbers
    Language: English
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  • 15
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    Phase Stability of Al‐Bearing Dense Hydrous Magnesium Silicates at Topmost Lower Mantle Conditions: Implication for Water Transport in the Mantle (2022)
    Details
    Publication Date: 2023-01-17
    Description: In this study, we investigated the phase stability of Al‐free and Al‐bearing superhydrous phase B (shy‐B) up to 55 GPa and 2500 K. In comparison with Al‐free shy‐B, the incorporation of 11.7 wt.% Al2O3 in shy‐B expands the stability by ∼400–800 K at 20–30 GPa. The determined dehydration boundary for Al‐bearing phase D indicates that it could be present even at normal mantle geotherm conditions at 30–40 GPa. Up to 23.8 mol.% Al2O3 can be dissolved into the structures of akimotoite and bridgmanite as a result of the decomposition reactions of Al‐bearing shy‐B and phase D between 20 and 40 GPa. Results of further experiments indicate that δ‐AlOOH is the stable hydrous phase coexisting with Al‐depleted bridgmanite at pressures above 52 GPa. This study shows that the incorporation of Al in dense hydrous magnesium silicates can have a profound impact on our picture of the water cycle in the deep Earth.
    Description: Plain Language Summary: Constraining the deep cycle of water has a tremendous impact on our picture of the current state of the Earth and the evolution of the Earth's interior. Dense hydrous magnesium silicates (DHMSs) are considered potential H2O carriers in the Earth's mantle. However, the DHMSs can only be present at the relatively cold conditions of subduction slabs due their limited thermal stability. We determined the phase stability of Al‐bearing DHMSs at high pressure and temperature (P‐T) conditions. Our results show that the thermal stability of Al‐bearing shy‐B extends by 400–800 K with respect to its Al‐free counterpart at 600–800 km depth. The incorporation of Al also expands the phase stability of phase D and enhances the likelihood of its occurrence at normal mantle conditions at 800–1100 km. In addition, we observe that 23.8 mol.% Al2O3 can be dissolved into the structures of akimotoite and bridgmanite as a result of the decomposition reactions of Al‐bearing shy‐B and phase D between 600 and 100 km depth. Furthermore, δ‐AlOOH is the stable hydrous phase coexisting with Al‐depleted bridgmanite in the MgO‐SiO2‐Al2O3‐H2O system at pressures above 52 GPa and 1500 K.
    Description: Key Points: In comparison with Al‐free shy‐B, the incorporation of 11.7 wt.% Al2O3 in superhydrous phase B (shy‐B) expands the stability by ∼400–800 K at 20–30 GPa. Al‐bearing phase D could be present even at normal mantle geotherm conditions at 30–40 GPa. δ‐AlOOH is the stable hydrous phase coexisting with Al‐depleted bridgmanite at pressures above 52 GPa.
    Description: Center for Molecular Water Science, CMWS
    Description: https://doi.org/10.5281/zenodo.6320835
    Keywords: ddc:549 ; Al‐bearing superhydrous phase B ; phase D ; phase stability ; high pressure and temperature ; deep Earth water cycle
    Language: English
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  • 16
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    Number of Chamber Measurement Locations for Accurate Quantification of Landscape‐Scale Greenhouse Gas Fluxes: Importance of Land Use, Seasonality, and Greenhouse Gas Type (2022)
    Wangari, E. G. ; Mwanake, R. M. ; Kraus, D. ; [et al.]
    Details
    Publication Date: 2023-01-17
    Description: Accurate quantification of landscape soil greenhouse gas (GHG) exchange from chamber measurements is challenging due to the high spatial‐temporal variability of fluxes, which results in large uncertainties in upscaled regional and global flux estimates. We quantified landscape‐scale (6 km2 in central Germany) soil/ecosystem respiration (SR/ER‐CO2), methane (CH4), and nitrous oxide (N2O) fluxes at stratified sites with contrasting landscape characteristics using the fast‐box chamber technique. We assessed the influence of land use (forest, arable, and grassland), seasonality (spring, summer, and autumn), soil types, and slope on the fluxes. We also evaluated the number of chamber measurement locations required to estimate landscape fluxes within globally significant uncertainty thresholds. The GHG fluxes were strongly influenced by seasonality and land use rather than soil type and slope. The number of chamber measurement locations required for robust landscape‐scale flux estimates depended on the magnitude of fluxes, which varied with season, land use, and GHG type. Significant N2O‐N flux uncertainties greater than the global mean flux (0.67 kg ha−1 yr−1) occurred if landscape measurements were done at 〈4 and 〈22 chamber locations (per km2) in forest and arable ecosystems, respectively, in summer. For CO2 and CH4 fluxes, uncertainties greater than the global median CO2‐C flux (7,500 kg ha−1 yr−1) and the global mean forest CH4‐C uptake rate (2.81 kg ha−1 yr−1) occurred at 〈2 forest and 〈6 arable chamber locations. This finding suggests that more chamber measurement locations are required to assess landscape‐scale N2O fluxes than CO2 and CH4, based on these GHG‐specific uncertainty thresholds.
    Description: Plain Language Summary: Greenhouse gas emissions are subject to high spatial and temporal variability, leading to large uncertainties in regional and global estimates. We quantified fluxes of soil and ecosystem respiration (SR/ER‐CO2), methane (CH4) and nitrous oxide (N2O) at the landscape scale (6 km2 in central Germany). We determine the number of measurement chambers required to estimate landscape fluxes within globally significant uncertainty thresholds. Our results show a stronger influence of season and land use, as opposed to soil type and topography. The number of chambers required for robust landscape‐wide flux estimates depended on the size of the fluxes, which varied by season, land use and GHG type. An increase in the number of monitoring sites significantly reduced the uncertainties estimation on the whole landscape. Significant uncertainties in N2O fluxes above the global annual mean was found when landscape measurements were made at 〈4 monitoring sites in forests and 〈22 monitoring sites (per km2) in cropland ecosystems during the summer period. For SR/ER‐CO2 fluxes, as few as 〈2 was sufficient in forest ecosystems and under 〈6 in cropland ecosystems. This result implies that in general more monitoring sites are needed to assess landscape‐scale N2O fluxes than for CO2 and CH4 fluxes.
    Description: Key Points: Land use and seasonality rather than soil type and slope strongly influenced soil greenhouse gas (GHG) fluxes at a landscape‐scale. The minimum number of chamber locations required for robust landscape‐scale flux estimates depends on the season, land use, and GHG type. Chamber locations required to reduce uncertainties of landscape flux estimates declined as follows N2O 〉 CO2 〉 CH4.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6821111
    Keywords: ddc:631.4 ; soil respiration ; ecosystem respiration ; methane uptake ; nitrous oxide fluxes ; spatial‐temporal variability ; stratfied sampling
    Language: English
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    Crustal Structure of the Indochina Peninsula From Ambient Noise Tomography (2022)
    Details
    Publication Date: 2023-01-17
    Description: The collision between the Indian and Eurasian plates promotes the southeastward extrusion of the Indochina Peninsula while the internal dynamics of its crustal deformation remain enigmatic. Here, we make use of seismic data from 38 stations and employ the ambient noise tomography to construct a 3‐D crustal shear‐wave velocity (Vs) model beneath the Indochina Peninsula. A low‐Vs anomaly is revealed in the mid‐lower crust of the Shan‐Thai Block and probably corresponds to the southern extension of the crustal flow from SE Tibet. Although the Khorat Plateau behaves as a rigid block, the observed low‐Vs anomalies in the lower crust and also below the Moho indicate that the crust may have been partially modified by mantle‐derived melts. The strike‐slip shearing motions of the Red River Fault may have dominantly developed crustal deformation at its western flank where a low‐Vs anomaly is observed at the upper‐middle crust.
    Description: Plain Language Summary: The Indochina Peninsula was believed to behave as a rigid block where significant southeastward extrusion and clockwise rotation have occurred in response to the collision between the Indian and Eurasian plates. Here, we employ ambient noise data to obtain the shear‐wave velocity (Vs) images and find deformations in the interior of the crust beneath the Indochina Peninsula. A low‐Vs anomaly is observed in the mid‐lower crust of the Shan‐Thai Block and represents the crustal flow from SE Tibet. The crust of the Khorat Plateau, the core of the Indochina Block, has been partially modified by mantle‐derived melts. The strike‐slip shearing motions of the Red River Fault have brought crustal deformation at its southwestern flank characterized as a low‐Vs anomaly in the upper‐middle crust.
    Description: Key Points: A 3‐D crustal shear‐wave velocity (Vs) model was constructed for the Indochina Peninsula from ambient noise tomography. Low‐Vs in the middle‐lower crust of the Shan‐Thai Block may represent the southern extension of the crustal flow from SE Tibet. The crust of the rigid Khorat Plateau has been partially modified by intrusion of mantle‐derived melts.
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Description: the State Key Laboratory of Marine Geology, Tongji University
    Description: Shanghai Sheshan National Geophysical Observatory
    Description: https://doi.org/10.5281/zenodo.5235658
    Keywords: ddc:551.1 ; Indochina Peninsula ; crustal structure ; lower‐crustal flow ; ambient noise tomography
    Language: English
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    Bergordnung Herzog Siegmund von Österreich für Schwaz (2023)
    Details
    Publication Date: 2023-01-11
    Description: Diese Bergordnung wurde am 7. Januar 1474 für die Bergwerke in Schwaz von Herzog Siegmund von Österreich erlassen. Mit dem ab 1470 stark ansteigenden Bergbauaktivitäten kam es gleichzeitig zu zahlreichen Missständen bei der Dienstdurchführung der Hutleute sowie zu offensichtlich chaotischen Zuständen bei der Vermessung der Grubenfelder. In 16 Paragrafen wurden deshalb die Rechte der Gruben an ihren Feldern, das ordentliche Vermessen der Grubenfelder und das Verhalten bei Durchschlägen beschrieben sowie die Zuständigkeiten der Hutleute klar benannt. In einem später eingefügten Zusatz wurde das Fällen von Bäumen im gesamten Bergbaubezirk verboten.
    Description: source
    Keywords: Herzog Siegmund von Österreich ; Österreich ; Tirol ; Schwaz ; Freundsberg, Burg ; Schlitters ; Innsbruck ; Silberbergbau ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
    Format: 7
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    Bias correction of daily precipitation for ungauged locations using geostatistical approaches: A case study for the CORDEX‐Africa ensemble (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-14
    Description: Climate model simulations typically exhibit a bias, which can be corrected using statistical approaches. In this study, a geostatistical approach for bias correction of daily precipitation at ungauged locations is presented. The method utilizes a double quantile mapping with dry day correction for future periods. The transfer function of the bias correction for the ungauged locations is established using distribution functions estimated by ordinary kriging with anisotropic variograms. The methodology was applied to the daily precipitation simulations of the entire CORDEX‐Africa ensemble for a study region located in the West African Sudanian Savanna. This ensemble consists of 23 regional climate models (RCM) that were run for three different future scenarios (RCP 2.6, RCP 4.5, and RCP 8.5). The evaluation of the approach for a historical 50‐year period (1950–2005) showed that the method can reduce the inherent strong precipitation bias of RCM simulations, thereby reproducing the main climatological features of the observed data. Moreover, the bias correction technique preserves the climate change signal of the uncorrected RCM simulations. However, the ensemble spread is increased due to an overestimation of the rainfall probability of uncorrected RCM simulations. The application of the bias correction method to the future period (2006–2100) revealed that annual precipitation increases for most models in the near (2020–2049) and far future (2070–2099) with a mean increase of up to 165mm⋅a−1 (18%). An analysis of the monthly and daily time series showed a slightly delayed onset and intensification of the rainy season.
    Description: Adapting water management strategies to future precipitation projected by climate models is associated with high uncertainty in sparsely gauged catchments. Kriging was utilized to estimate distribution parameters for ungauged locations in a West African region to perform a bias correction of the CORDEX‐Africa ensemble. The application of the bias correction method revealed higher annual precipitation amounts and an intensifaction of the rainy season but only little change to the onset of the rainy season.
    Description: German Federal Ministry of Education and Research, Bonn (BMBF), West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL)
    Keywords: ddc:551.6 ; bias correction ; climate change ; CORDEX‐Africa ; geostatistical approaches ; precipitation ; quantile mapping ; West Africa
    Language: English
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    Non‐ and sub‐state climate action after Paris: From a facilitative regime to a contested governance landscape (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-14
    Description: The Paris Agreement marks a significant milestone in international climate politics. With its adoption, Parties call for non‐ and sub‐state actors to contribute to the global climate agenda and close the emissions gap left by states. Such a facilitative setting embraces non‐state climate action through joint efforts, synergies, and different modes of collaboration. At the same time, non‐state actors have always played a critical and confrontational role in international climate governance. Based on a systematic literature review, we identify and critically assess the role of non‐state climate action in a facilitative post‐Paris climate governance regime. We thereby highlight three constitutive themes, namely different state‐non‐state relations, competing level of ambition, and a variety of knowledge foundations. We substantiate these themes, derived from an inductive analysis of existing literature, with illustrative examples and propose three paradigmatic non‐state actor roles in post‐Paris climate governance on a continuum between compliance and critique. We thereby highlight four particular threats of a facilitative setting, namely substitution of state action, co‐optation, tokenism, and depoliticization. Future research should not limit itself to an effective integration of NSSAs into a facilitative climate regime, but also engage with the merits of contestation. This article is categorized under: Policy and Governance 〉 Multilevel and Transnational Climate Change Governance
    Description: Three constitutive themes—different state‐non‐state relations, levels of ambition, and knowledge foundations—define the multiple roles non‐ and sub‐state actors can occupy in the post‐Paris climate governance regime. Yet, calls for voluntary, collaborative, and synergetic non‐state climate action in a facilitative post‐Paris climate governance setting run the risk to overshadow fundamental tensions when governing climate change.
    Description: Svenska Forskningsrådet Formas http://dx.doi.org/10.13039/501100001862
    Description: Deutsche Forschungsgemeinschaft (DFG)
    Keywords: ddc:341.7 ; climate change governance ; contestation ; environmental politics ; non‐state actors ; Paris Agreement ; transformation
    Language: English
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    Investment traps and resilience to shocks: An experimental study of Central Asian collective water governance (2022)
    Details
    Publication Date: 2023-01-14
    Description: We theoretically and empirically investigate the investments of water users in a stylized local irrigation system. We model irrigation self‐management as an interdependent interaction of users in an evolutionary game and study the resilience of the irrigation system. The theoretical model implies multiple stable equilibria at different efficiency levels. Users may be trapped in a low level of collective investment or succeed by being locked in a high collective investment level, implying an irrigation system resilient against external shocks. The study seeks to empirically identify such lock‐ins in experimental interactions among Central Asian farmers. Furthermore, we inquire into whether a pre‐play cheap talk opportunity with peer‐monitoring or sanctioning treatments influence the self‐reinforcing dynamic. Our findings revealed several stable states. Among these states, there are both low and high levels of efficiency, which we measure in the size of public good. Communication among users results in higher collective investment levels. However, this does not guarantee the complete elimination of inferior conventions from best‐response play. Penalties crowded out the intrinsic motivation to cooperate as they reduced collective investment in both low‐ and high‐level equilibria. Our findings imply that institutional settings tailored to each community can improve resilience to climate‐driven perturbations in water resources.
    Description: VolkswagenStiftung (Volkswagen Foundation) http://dx.doi.org/10.13039/501100001663
    Description: Federal Ministry for Economic Cooperation (BMZ) http://dx.doi.org/10.13039/501100001663
    Keywords: ddc:333.91 ; Central Asia ; experiment ; multiple equilibria ; resilience ; water management ; Asie centrale ; expérimentation ; équilibres multiples ; résilience ; gestion de l'eau
    Language: English
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    Developing a Laser Induced Liquid Beam Ion Desorption Spectral Database as Reference for Spaceborne Mass Spectrometers (2022)
    Details
    Publication Date: 2023-01-14
    Description: Spaceborne impact ionization mass spectrometers, such as the Cosmic Dust Analyzer on board the past Cassini spacecraft or the SUrface Dust Analyzer being built for NASA's upcoming Europa Clipper mission, are of crucial importance for the exploration of icy moons in the Solar System, such as Saturn's moon Enceladus or Jupiter's moon Europa. For the interpretation of data produced by these instruments, analogue experiments on Earth are essential. To date, thousands of laboratory mass spectra have been recorded with an analogue experiment for impact ionization mass spectrometers. Simulation of mass spectra of ice grains in space is achieved by a Laser Induced Liquid Beam Ion Desorption (LILBID) approach. The desorbed cations or anions are analyzed in a time‐of‐flight mass spectrometer. The amount of unstructured raw data is increasingly challenging to sort, process, interpret and compare with data from space. Thus far this has been achieved manually for individual mass spectra because no database containing the recorded reference spectra was available. Here we describe the development of a comprehensive, extendable database containing cation and anion mass spectra from the laboratory LILBID facility. The database is based on a Relational Database Management System with a web server interface and enables filtering of the laboratory data using a wide range of parameters. The mass spectra can be compared not only with data from past and future space missions but also mass spectral data generated by other, terrestrial, techniques. The validated and approved subset of the database is available for general public (https://lilbid-db.planet.fu-berlin.de).
    Description: Plain Language Summary: Thousands of laboratory mass spectra, each with an individual set of experimental parameters, have been recorded so far using a facility situated at Freie Universität Berlin, Germany. The mass spectra help analyze and interpret data returned from spacecraft in the vicinity of icy moons in the Solar System. The unstructured laboratory data is increasingly challenging to sort and compare to the data from space. We developed an extendable database containing the laboratory data. The database is available for general public and allows filtering the stored data for a wide range of experimental parameters and, in turn, significantly improves analysis of data not only from past space missions but also future missions in particular.
    Description: Key Points: We describe the development of a comprehensive spectral database containing laboratory analogue data for spaceborne mass spectrometers. The database is based on a Relational Database Management System with a web interface and accessible for community use. Filtering the laboratory data using a wide range of experimental parameters allows a straightforward analysis of returned flight data.
    Description: EC, Horizon 2020 Framework Programme (H2020) http://dx.doi.org/10.13039/100010661
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6863855
    Description: https://sbnarchive.psi.edu/pds3/cassini/cda/COCDA_0007.tar.gz
    Keywords: ddc:550 ; mass spectral database ; analogue experiments ; ice grains ; ocean worlds ; SUDA ; ENIA ; LILBID ; TOF‐MS
    Language: English
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    An Analytical Framework for Determining the Ecological Risks of Wastewater Discharges in River Networks Under Climate Change (2022)
    Details
    Publication Date: 2023-01-14
    Description: Over the last decades, treatment of domestic wastewater promoted by environmental regulations have reduced human health risks and improved water quality. However, ecological risks caused by effluents of wastewater treatment plants (WWTPs) discharged into rivers still persist. Moreover, the evolution of these ecological risks in the future is intimately related to effects of changing climate, especially regarding streamflow in receiving rivers. Here, we present an analytical and transferable framework for assessing the ecological risks posed by WWTP‐effluents at the catchment scale. The framework combines the size‐class k of WWTPs, which is a load‐proxy, with their outflows' location in river networks, represented by stream‐order ω. We identify ecological risks by using three proxy indicators: the urban discharge fraction and the local‐scale concentrations of each total phosphorous and ammonium‐nitrogen discharged from WWTPs. About 3,200 WWTPs over three large catchments (Rhine, Elbe, and Weser) in Central Europe were analyzed by incorporating simulated streamflow for the most extreme projected climate change scenario. We found that WWTPs causing ecological risks in the future prevail in lower ω, across almost all k. Distinct patterns of ecological risks are identified in the k‐ω framework for different indicators and catchments. We show, as climate changes, intensified risks are especially expected in lower ω receiving effluents of intermediate‐k WWTPs. We discuss the implications of our findings for prioritizing WWTPs upgrading and urging updates on environmental regulations. Further discussions underline the feasibility of applying the framework to any geographical regions and highlight its potentials to help in achieving global long‐term commitments on freshwater security.
    Description: Key Points: An analytical, generic framework was developed to assess wastewater treatment plants causing ecological risks in rivers under climate change. Smaller streams will face higher ecological risks for almost all load classes of wastewater treatment plants in future climate. Of the legally regulated effluent parameters for treated wastewater, ammonium‐nitrogen concentration will pose the greatest ecological risk.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Keywords: ddc:551.48 ; analytical assessment framework ; wastewater treatment plants emissions ; river stream‐order ; dilution ; local‐scale nutrients concentrations
    Language: English
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    Horizontal Wavenumber Spectra of Vertical Vorticity and Horizontal Divergence of Mesoscale Dynamics in the Mesosphere and Lower Thermosphere Using Multistatic Specular Meteor Radar Observations (2022)
    Details
    Publication Date: 2023-01-14
    Description: Specular meteor radars (SMRs) have significantly contributed to the understanding of wind dynamics in the mesosphere and lower thermosphere (MLT). We present a method to estimate horizontal correlations of vertical vorticity (Qzz) and horizontal divergence (P) in the MLT, using line‐of‐sight multistatic SMRs velocities, that consists of three steps. First, we estimate 2D, zonal, and meridional correlation functions of wind fluctuations (with periods less than 4 hr and vertical wavelengths smaller than 4 km) using the wind field correlation function inversion (WCFI) technique. Then, the WCFI's statistical estimates are converted into longitudinal and transverse components. The conversion relation is obtained by considering the rotation about the vertical direction of two velocity vectors, from an east‐north‐up system to a meteor‐pair‐dependent cylindrical system. Finally, following a procedure previously applied in the upper troposphere and lower stratosphere to airborne wind measurements, the longitudinal and transverse spatial correlations are fitted, from which Qzz, P, and their spectra are directly estimated. The method is applied to a special Spread spectrum Interferometric Multistatic meteor radar Observing Network data set, obtained over northern Germany for seven days in November 2018. The results show that in a quasi‐axisymmetric scenario, P was more than five times larger than Qzz for the horizontal wavelengths range given by ∼50–400 km, indicating a predominance of internal gravity waves over vortical modes of motion as a possible explanation for the MLT mesoscale dynamics during this campaign.
    Description: Key Points: We investigate the horizontal correlation functions of vertical vorticity and horizontal divergence for mesoscale wind fluctuations in the mesosphere and lower thermosphere. 2D zonal and meridional correlation functions and 1D longitudinal and transverse correlation functions as a function of horizontal lags are analyzed. The divergence dominated over the vorticity during November 2018 in northern Germany.
    Description: Leibniz SAW
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: French Ministry of Foreign and European
    Description: https://doi.org/10.22000/536
    Keywords: ddc:551.5 ; MLT ; vorticity ; correlation function ; meteor radar ; mesoscales ; divergence
    Language: English
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    High‐Resolution Aircraft Observations of Turbulence and Waves in the Free Atmosphere and Comparison With Global Model Predictions (2022)
    Details
    Publication Date: 2023-01-14
    Description: High‐resolution flight data obtained from in situ measurements in the free atmosphere aboard the High Altitude and Long Range Research Aircraft (HALO) are used to determine eddy dissipation rates along extended flights during the recent Southern Hemisphere Transport, Dynamics, and Chemistry aircraft campaign (SOUTHTRAC) in the 2019 austral winter. These data are analyzed and correlated with quantities characterizing the ambient airflow and the magnitudes of vertical energy propagation through internal gravity waves. The observed turbulence events are strongly correlated with elevated shear values, and overturning gravity waves do not appear to play a role. A highlight of the analysis is the validation of a recently implemented Clear Air Turbulence (CAT) forecast index in the European Centre for Medium‐Range Weather Forecast integrated forecast system. Here we find a slightly better correlation of the CAT prediction with the HALO research aircraft observations compared to those of commercial aircraft. The observed turbulence during SOUTHTRAC was never stronger than moderate, as EDR values remained below 0.3 m2/3 s−1. In general, light and light‐to‐moderate turbulence events were extremely rare, occurring in only about 5% of the flight time, and stronger events in less than 0.2%. These results are also reflected in the local atmospheric conditions, which were dominated by a thermally very stable airflow with low vertical shear and large Richardson numbers.
    Description: Plain Language Summary: This study analyzes high‐resolution data of velocity components in the upper troposphere and lower stratosphere collected with the German research aircraft High Altitude and Long Range Research Aircraft during the Southern Hemisphere Transport, Dynamics, and Chemistry (SOUTHTRAC) campaign in September–November 2019. Flights were conducted predominantly over the southern part of South America, the Drake Passage, and the Antarctic Peninsula. The objective of the analysis was to determine the eddy dissipation rates during the 22 flights. The cubic root of eddy dissipation rates is a common measure used to characterize turbulent regions in the atmosphere. High quality observations with a very accurately calibrated sensor are rare, especially in the remote areas of the SOUTHTRAC campaign. Observed eddy dissipation rates have been correlated with gravity wave activity, but these correlations are very small. A much stronger dependence of the eddy dissipation rates exists on the vertical shear of the horizontal wind. Thus, mechanical generation of turbulence appears to dominate in the observed cases. Overall, the observed turbulence was never stronger than moderate. Turbulence events were extremely rare, occurring in only about 5% of the flight time, and stronger events less than 0.2%. Finally, the observed eddy dissipation rates were compared with weather model forecasts, demonstrating their reliability in predicting turbulent regions.
    Description: Key Points: Small eddy dissipation rates were observed in the free atmosphere along extended research flights during Southern Hemisphere Transport, Dynamics, and Chemistry in austral winter 2019. Stronger turbulence events are rare and are mostly correlated with enhanced vertical shear of the horizontal wind. EDR predictions of a 15‐member ensemble shows higher correlation with research aircraft observations than with those by commercial aircraft.
    Description: Federal Ministry for Education and Research
    Description: German Science Foundation
    Description: https://halo-db.pa.op.dlr.de/mission/116
    Description: https://halo-db.pa.op.dlr.de/dataset/8497
    Description: https://halo-db.pa.op.dlr.de/dataset/8496
    Description: https://apps.ecmwf.int/codes/grib/param-db/?id=260290
    Description: https://doi.org/10.21957/xbar-5611
    Description: https://halo-db.pa.op.dlr.de/dataset/8955
    Description: https://madis.ncep.noaa.gov/acars_variable_list.shtml
    Keywords: ddc:551.5 ; turbulence in the free atmosphere ; eddy dissipation rate ; clear‐air turbulence predictions ; ECMWF integrated forecast system
    Language: English
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    Identifying Dominant Processes in Time and Space: Time‐Varying Spatial Sensitivity Analysis for a Grid‐Based Nitrate Model (2022)
    Details
    Publication Date: 2023-01-14
    Description: Distributed models have been increasingly applied at finer spatiotemporal resolution. However, most diagnostic analyses aggregate performance measures in space or time, which might bias subsequent inferences. Accordingly, this study explores an approach for quantifying the parameter sensitivity in a spatiotemporally explicit way. We applied the Morris method to screen key parameters within four different sampling spaces in a grid‐based model (mHM‐Nitrate) for NO3‐N simulation in a mixed landuse catchment using a 1‐year moving window for each grid. The results showed that an overly wide range of aquatic denitrification rates could mask the sensitivity of the other parameters, leading to their spatial patterns only related to the proximity to outlet. With adjusted parameter space, spatial sensitivity patterns were determined by NO3‐N inputs and hydrological transport capacity, while temporal dynamics were regulated by annual wetness conditions. The relative proportion of parameter sensitivity further indicated the shifts in dominant hydrological/NO3‐N processes between wet and dry years. By identifying not only which parameter(s) is(are) influential, but where and when such influences occur, spatial sensitivity analysis can help evaluate current model parameterization. Given the marked sensitivity in agricultural areas, we suggest that the current NO3‐N parameterization scheme (land use‐dependent) could be further disentangled in these regions (e.g., into croplands with different rotation strategies) but aggregated in non‐agricultural areas; while hydrological parameterization could be resolved into a finer level (from spatially constant to land use‐dependent especially in nutrient‐rich regions). The spatiotemporal sensitivity pattern also highlights NO3‐N transport within soil layers as a focus for future model development.
    Description: Key Points: A diagnostic analysis was conducted to disentangle the parameter sensitivity for NO3‐N simulations in catchment modeling in space and time. Sensitivity differed within sampling spaces, but was controlled spatially by NO3‐N supply/water fluxes while temporally by wetness condition. Analysis suggests finer‐level parameterization needs in arable land, and prioritizes NO3‐N transport in soils for improved conceptualization.
    Description: Chinese Scholarship Council
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Berlin University Alliance http://dx.doi.org/10.13039/501100021727
    Description: https://doi.org/10.5281/zenodo.6497225
    Description: https://fred.igb-berlin.de/data/package/629
    Keywords: ddc:551 ; spatial time‐varying sensitivity analysis ; distributed nitrate modeling
    Language: English
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    Distribution, drivers and population structure of the invasive alien snail Tarebia granifera in the Luvuvhu system, South Africa (2022)
    Makherana, Fhatuwani ; Cuthbert, Ross N. ; Dondofema, Farai ; [et al.]
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-14
    Description: Invasive alien species continue to spread and proliferate in waterways worldwide, but environmental drivers of invasion dynamics lack assessment. Knowledge gaps are pervasive in the Global South, where the frequent heavy human‐modification of rivers provides high opportunity for invasion. In southern Africa, the spatio‐temporal ecology of a widespread and high‐impact invasive alien snail, Tarebia granifera, and its management status is understudied. Here, an ecological assessment was conducted at seven sites around Nandoni Reservoir on the Luvuvhu River in South Africa. The distribution and densities of T. granifera were mapped and the potential drivers of population structure were explored. T. granifera was widespread at sites impacted to varying extents due to anthropogenic activity, with densities exceeding 500 individuals per square meter at the most impacted areas. T. granifera predominantly preferred shallow and sandy environments, being significantly associated with sediment (i.e., chlorophyll‐a, Mn, SOC, SOM) and water (i.e., pH, conductivity, TDS) variables. T. granifera seemed to exhibit two recruitment peaks in November and March, identified via size‐based stock assessment. Sediment parameters (i.e., sediment organic matter, sediment organic carbon, manganese) and water chemistry (i.e., pH, total dissolved solids, conductivity) were found to be important in structuring T. granifera populations, with overall snail densities highest during the summer season. We provide important autecological information and insights on the distribution and extent of the spread of T. granifera. This may help in the development of invasive alien snail management action plans within the region, as well as modelling efforts to predict invasion patterns elsewhere based on environmental characteristics.
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: National Research Foundation http://dx.doi.org/10.13039/501100001321
    Description: University of Venda http://dx.doi.org/10.13039/501100008976
    Keywords: ddc:577.6 ; aquatic non‐native invasions ; environmental gradients ; Global South ; human‐modified river ; quilted melania ; reservoir
    Language: English
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    Spatio‐Temporal Level Variations of the Martian Seasonal North Polar Cap From Co‐Registration of MOLA Profiles (2022)
    Xiao, Haifeng ; Stark, Alexander ; Schmidt, Frédéric ; [et al.]
    Details
    Publication Date: 2023-01-14
    Description: The seasonal deposition and sublimation of CO2 constitute a major element in Martian volatile cycles. We reprocess the Mars Orbiter Laser Altimeter (MOLA) data and apply co‐registration procedures to obtain spatio‐temporal variations in levels of the Seasonal North Polar Cap (SNPC). The maximum level over the Residual North Polar Cap (RNPC) is 1.3 m, approximately half of that at the south pole (2.5 m). However, the maximum level in the dune fields at Olympia Undae can be up to 3.8 m. Furthermore, off‐season decreases up to 3 m during the northern winter at Olympia Undae are observed. These are likely due to metamorphism effects accentuated by the reduced snowfall at this period. Meanwhile, off‐season increases of up to 2 m during the northern spring are noted, the cause of which remains to be explored. The volume of the SNPC peaks at the end of northern winter and is estimated to be approximately 9.6 × 1012 m3, which is 2% more than that of the Seasonal South Polar Cap. The bulk density of the SNPC can go through phased decreases in accordance with phased accumulation at northern high‐latitudes. These findings can put important constraints on the Martian volatile cycling models.
    Description: Plain Language Summary: Due to its axial tilt, seasons also exist on Mars. Up to one third of the atmosphere's CO2 is in annual exchange with the polar regions through seasonal deposition/sublimation processes. Here, we make use of previously proposed approaches of analyzing the Mars Orbiter Laser Altimeter profiles and obtain spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC). Particularly, we bring attention to abnormal behavior of the SNPC in the dune fields at Olympia Undae. Maximum level there can be all the way up to 4 m which is much higher than a maximum of 1.5 m over the Residual North Polar Cap. Meanwhile, off‐season decreases during the northern winter with magnitudes up to 3 m and off‐season increases during the northern spring of magnitudes up to 2 m are observed. These could possibly be related to metamorphism of the seasonal deposits and phased snowfall. The maximum volume of the SNPC is constrained to be 9.6 × 1012 m3. The bulk density of the SNPC does not continuously increase as previously assumed but can go through phased decreases in accordance with phased snowfall at the north pole. These findings can put important constraints on the Martian climate models.
    Description: Key Points: Through co‐registration of laser altimetry profiles, spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC) of Mars are obtained. Maximum level of the SNPC can be up to 3.8 m at Olympia Undae and up to 1.3 m over the Residual North Polar Cap. Northern winter decreases of up to 3 m and northern spring increases of up to 2 m are observed at Olympia Undae.
    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://doi.org/10.17632/x953mzxxvv.1
    Description: https://doi.org/10.17632/z59b9nd6s9.2
    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://www.uahirise.org/hiwish/browse
    Keywords: ddc:523 ; Mars ; seasonal polar cap ; CO2 ice ; MOLA ; level variation ; pseudo cross‐over
    Language: English
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    Non‐Isotropic Contraction and Expansion of Samples in Diamond Anvil Cells: Implications for Thermal Conductivity at the Core‐Mantle Boundary (2022)
    Details
    Publication Date: 2023-01-13
    Description: The thermal conductivities of mantle and core materials have a major impact on planetary evolution, but their experimental determination requires precise knowledge of sample thickness at high pressure. Despite its importance, thickness in most diamond anvil cell (DAC) experiments is not measured but inferred from equations of state, assuming isotropic contraction upon compression or assuming isotropic expansion upon decompression. Here we provide evidence that in DAC experiments both assumptions are invalid for a range of mechanically diverse materials (KCl, NaCl, Ar, MgO, silica glass, Al2O3). Upon compression, these samples are ∼30–50% thinner than expected from isotropic contraction. Most surprisingly, all the studied samples continue to thin upon decompression to 10–20 GPa. Our results partially explain some discrepancies among the highly controversial thermal conductivity values of iron at Earth's core conditions. More generally, we suggest that in situ characterization of sample geometry is essential for conductivity measurements at high pressure.
    Description: Plain Language Summary: The thermal and electrical conductivities of the materials making up Earth's core and lowermost mantle are crucial inputs for modeling Earth's interior and the geodynamo mechanism. Yet, large disagreements between published values of conductivity are common, including a factor‐of‐seven discrepancy in the thermal conductivity of iron at core‐mantle boundary conditions. One possible source of systematic uncertainty is the estimate of sample thickness during high‐pressure experiments. Here we show that common materials in compression experiments tend to thin by much more than previously assumed. Surprisingly, the thinning continues upon decompression. These thinning trends could lead to ∼30–50% systematic error, partially explaining the discrepancy in iron conductivity. In situ thickness measurements are thus crucial for accurate determination of conductivities of Earth's mantle and core.
    Description: Key Points: Samples in diamond anvil cell experiments contract and expand in a strongly non‐isotropic fashion upon compression and decompression. Experimental reports on iron conductivity at high pressure contain errors due to the assumption of isotropic contraction or expansion. Accurate in situ determination of sample geometry is necessary for thermal and electrical conductivity measurements at high pressure.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.17632/wnvbty8y83.4
    Keywords: ddc:551.12 ; diamond anvil cell ; thermal conductivity ; high pressure
    Language: English
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    D" Reflection Polarities Inform Lowermost Mantle Mineralogy (2022)
    Details
    Publication Date: 2023-01-13
    Description: Polarities of seismic reflections at the discontinuity atop the D" region (PdP and SdS) indicate the sign of the velocity contrast across the D" reflector. Recent studies found PdP polarities matching and opposite those of P and PcP. While anisotropy could explain this behavior, we find that the ratio of the change in S wave velocity over change in P wave velocity (R‐value) can influence polarity behavior of D" reflected P waves. For R‐values exceeding 3, the P wave reverses polarity in the absence of anisotropy while S wave polarity is not influenced by the R‐value. Using sets of one million models for normal mantle and MORB with varying minerals and processes across the boundary, we carry out a statistical analysis (Linear Discriminant Analysis) finding that there is a marked difference in mantle mineralogy to explain R‐values larger and smaller than 3, respectively. Based on our results we can attribute different mineralogy to a number of cases. In particular, we find that when velocities increase across D" and polarities of PdP and SdS are opposite the post‐perovskite phase transition is still the best explanation whereas MORB is the best explanation when PdP and SdS are the same. When the velocities are decreasing, the post‐perovskite phase transition within MORB is the best explanation if PdP and SdS polarities are the same but if PdP and SdS are opposite, our results indicate that primordial material or mantle enriched in bridgmanite can explain the polarity behavior, further constraining mineralogy within the large low seismic velocity provinces.
    Description: Plain Language Summary: Polarities of seismic waves reflecting at structures in the Earth's mantle indicate seismic velocity changes there. For the lowermost mantle reflector, a velocity increase generates a polarity that is the same for the main wave and the core‐reflected wave. If, however, the percentage change of the velocity of the S wave increases at least three times as much as that of the P wave velocity (expressed as the R‐value, the ratio dVs/dVp), the polarity of the D"‐reflected PdP wave changes polarity, becoming opposite to both the main P wave and the reflection from the core‐mantle boundary below it. Here, we analyze sets of 1 million models with variable compositions of mantle material and mid‐ocean ridge basalt and use an advanced statistical method to identify those combinations of minerals that produce large positive R‐values. We distinguish four cases and find that previous explanations for three of these cases concur with our analysis. For regions where velocities decrease over the D" reflector, our analysis shows that enrichment with the lower‐mantle mineral bridgmanite is responsible for the observed polarity behavior of P and S waves. This means that for regions such as large low‐velocity anomalies in the lowermost mantle, primitive or bridgmanite‐enriched material is the preferred explanation.
    Description: Key Points: Ratio (R) of S‐ over P wave velocity changes (%) controls the polarity of P wave reflections at D" reflector. Thermochemical modeling and statistical analysis show specific minerals contributing to large R‐values. Polarity observations indicate that part of the Pacific large low seismic velocity province is due to bridgmanite enrichment.
    Description: Deutsche Forschungsgemeinschaft and Agence Nationale de la Recherche http://dx.doi.org/10.13039/501100001659
    Description: Nederlandse Organisatie voor Wetenschappelijk Onderzoek http://dx.doi.org/10.13039/501100003246
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: https://doi.org/10.7914/SN/XE_2003
    Description: https://doi.org/10.7914/SN/TA
    Keywords: ddc:551.12 ; seismology ; wave polarity ; statistics ; thermochemical modeling ; D
    Language: English
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    A review on risk assessment in managed aquifer recharge (2022)
    Details
    Publication Date: 2023-01-13
    Description: Managed aquifer recharge (MAR) refers to a suite of methods that is increasingly being applied worldwide for sustainable groundwater management to tackle drinking or irrigation water shortage or to restore and maintain groundwater ecosystems. The potential for MAR is far from being exhausted, not only due to geological and hydrogeological conditions or technical and economic feasibility but also due to its lack of acceptance by the public and policymakers. One approach to enable the safe and accepted use of MAR could be to provide comprehensive risk management, including the identification, analysis, and evaluation of potential risks related to MAR. This article reviews current MAR risk assessment methodologies and guidelines and summarizes possible hazards and related processes. It may help planners and operators select the appropriate MAR risk assessment approaches and support the risk identification process. In addition to risk assessment (and subsequent risk treatment) related to the MAR implementation phase, this review also addresses risk assessment for MAR operation. We also highlight the limitations and lessons learned from the application and development of risk assessment methodologies. Moreover, developments are recommended in the area of MAR‐related risk assessment methodologies and regulation. Depending on data availability, collected methodologies may be applicable for MAR sites worldwide. Integr Environ Assess Manag 2022;18:1513–1529. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
    Description: Key Points: The past two decades have seen a marked increase in the literature on MAR‐related risk assessment, and a further increase is expected, since more attractive strategies are being used worldwide for integrated groundwater management. The development of holistic risk management plans can improve social acceptability and contribute to safer implementation and operation of MAR schemes. In connection with holistic risk management, MAR can be seen as a viable option for reaching the United Nations Sustainable Development Goal #6. Widely lacking regulations worldwide for risk assessment of MAR schemes is identified to hinder MAR implementation and safe operation worldwide.
    Description: DEEPWATER‐CE
    Description: ENeRAG
    Keywords: ddc:553.7 ; Groundwater management ; Guidelines ; Managed aquifer recharge ; Methodologies ; Risk assessment
    Language: English
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    Eruption Forecasting of Strokkur Geyser, Iceland, Using Permutation Entropy (2022)
    Details
    Publication Date: 2023-01-13
    Description: A volcanic eruption is usually preceded by seismic precursors, but their interpretation and use for forecasting the eruption onset time remain a challenge. A part of the eruptive processes in open conduits of volcanoes may be similar to those encountered in geysers. Since geysers erupt more often, they are useful sites for testing new forecasting methods. We tested the application of Permutation Entropy (PE) as a robust method to assess the complexity in seismic recordings of the Strokkur geyser, Iceland. Strokkur features several minute‐long eruptive cycles, enabling us to verify in 63 recorded cycles whether PE behaves consistently from one eruption to the next one. We performed synthetic tests to understand the effect of different parameter settings in the PE calculation. Our application to Strokkur shows a distinct, repeating PE pattern consistent with previously identified phases in the eruptive cycle. We find a systematic increase in PE within the last 15 s before the eruption, indicating that an eruption will occur. We quantified the predictive power of PE, showing that PE performs better than seismic signal strength or quiescence when it comes to forecasting eruptions.
    Description: Plain Language Summary: When a volcano shows the first sign of activity, it is challenging to determine whether and when the actual eruption will occur. Usually, researchers create earthquake lists and locate these events to assess this. However, an alternative and simpler method can be directly applied to continuous seismic data. We tested a method that assesses the complexity of signals. We first created synthetic data to find reasonable parameter settings for this method. While volcanoes do not erupt very often, frequent eruptions at geysers allow us to systematically study and compare several eruptions. We analyzed the continuous record of 63 eruptions of the Strokkur geyser, Iceland. Our results show a distinct pattern that repeats from one eruption to the next one. We also find a clear pattern that indicates about 15 s before the next eruption that an eruption will occur. We show that this method performs better in eruption forecasting than assessing the seismic noise or silence caused by the geyser.
    Description: Key Points: Permutation Entropy (PE) is a simple tool to assess the complexity of a time series. We analyzed the PE evolution for 63 eruptive cycles of Strokkur geyser and found characteristic changes in PE during recharge. PE is found to be an useful statistical predictor of the eruption times and highlights the precursor 15 s before eruptions.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: https://geofon.gfz-potsdam.de/doi/network/7L/2017
    Description: https://gitup.uni-potsdam.de/pujiastutisudibyo/permutationentropy
    Keywords: ddc:551.21 ; permutation entropy ; forecasting ; geyser ; eruption ; hydrothermal system ; volcano‐seismology
    Language: English
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    Ice Aggregation in Low‐Level Mixed‐Phase Clouds at a High Arctic Site: Enhanced by Dendritic Growth and Absent Close to the Melting Level (2022)
    Details
    Publication Date: 2023-01-13
    Description: Low‐level mixed‐phase clouds (MPCs) occur extensively in the Arctic, and are known to play a key role for the energy budget. While their characteristic structure is nowadays well understood, the significance of different precipitation‐formation processes, such as aggregation and riming, is still unclear. Using a 3‐year data set of vertically pointing W‐band cloud radar and K‐band Micro Rain Radar (MRR) observations from Ny‐Ålesund, Svalbard, we statistically assess the relevance of aggregation in Arctic low‐level MPCs. Combining radar observations with thermodynamic profiling, we find that larger snowflakes (mass median diameter larger than 1 mm) are predominantly produced in low‐level MPCs whose mixed‐phase layer is at temperatures between −15 and −10°C. This coincides with the temperature regime known for favoring aggregation due to growth and subsequent mechanical entanglement of dendritic crystals. Doppler velocity information confirms that these signatures are likely due to enhanced ice particle growth by aggregation. Signatures indicative of enhanced aggregation are however not distributed uniformly across the cloud deck, and only observed in limited regions, suggesting a link with dynamical effects. Low Doppler velocity values further indicate that significant riming of large particles is unlikely at temperatures colder than −5°C. Surprisingly, we find no evidence of enhanced aggregation at temperatures warmer than −5°C, as is typically observed in deeper cloud systems. Possible reasons are discussed, likely connected to the ice habits that form at temperatures warmer than −10°C, increased riming, and lack of particle populations characterized by broader size distributions precipitating from higher altitudes.
    Description: Plain Language Summary: Low‐level mixed‐phase clouds (MPCs), that is, shallow clouds containing both liquid droplets and ice crystals, form frequently in the Arctic region. Their characteristic structure—consisting of one or multiple liquid layers at sub‐zero temperatures, from which ice crystals form and precipitate—is nowadays well understood. However, the processes that lead to the growth of ice crystals into snow have been overlooked. Using a 3‐year data set of radar observations from Ny‐Ålesund, in Svalbard, Norway, we are able to identify situations when the ice particle growth is dominated by aggregation of several individual crystals. Combining radar observations with temperature information, we find that larger snowflakes are only produced in MPCs if their liquid portion is at temperatures between −15 and −10°C. This coincides with the temperature regime known for favoring aggregation due to growth and subsequent entanglement of branched crystals. Surprisingly, we find no evidence of enhanced ice aggregation at temperatures warmer than −5°C, as is typically observed in deeper cloud systems. Possible reasons are discussed, likely connected to the ice crystal shapes that develop at temperatures warmer than −10°C, increased liquid droplet production, and lack of particles precipitating from higher altitudes.
    Description: Key Points: Low‐level mixed‐phase clouds (MPCs) at Ny‐Ålesund produce large aggregates predominantly at dendritic‐growth temperatures. Enhanced aggregation due to dendritic growth occurs intermittently in limited regions of the MPC. The typically observed enhanced aggregation zone close to 0°C is absent in low‐level MPCs at the site.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.5 ; Arctic mixed‐phase clouds ; aggregation ; riming ; dendritic‐growth zone ; radar
    Language: English
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    Multi‐episodic formation of baddeleyite and zircon in polymetamorphic anorthosite and rutile‐bearing ilmenitite from the Chiapas Massif Complex, Mexico (2022)
    Details
    Publication Date: 2023-01-13
    Description: Massif‐type anorthosite and comagmatic associations of rutile‐bearing ilmenitite (RBI) and oxide‐apatite‐rich amphibolite (OARA) from the Chiapas Massif Complex (CMC) in southeastern Mexico display a protracted billion‐year accessory mineral record encompassing magmatic crystallization at c. 1.0 Ga to recent ductile shear deformation at c. 3.0 Ma. Multiple discrete zircon populations between these age end‐members resulted from neoformation/recrystallization during local to regional metamorphism that affected the southeastern portion of the CMC. The ubiquitous presence of relict baddeleyite (ZrO2), along with various zircon generations spatially associated with pristine to partly retrogressed Zr‐bearing igneous and metamorphic minerals (e.g., ilmenite, rutile, högbomite and garnet), suggests significant Zr diffusive re‐equilibration (exsolution) during slow cooling and mineral breakdown followed by crystallization of baddeleyite. The subsequent transformation of baddeleyite into zircon was likely driven by reaction with Si‐bearing fluids in several geochronologically identified metamorphic stages. Strikingly contrasting compositional signatures in coeval zircon from anorthosite (silicate‐dominated) and comagmatic RBI (Ti‐Fe‐oxide‐dominated) indicate a major role of fluids locally equilibrating with the rock matrix, as indicated by distinct zircon trace element and oxygen isotopic compositions. A high‐grade metamorphic event at c. 950 Ma is likely responsible for the formation of coarse‐grained rutile (~0.1–10 mm in diameter), srilankite, zircon and garnet with rutile inclusions as well as metamorphic högbomite surrounding Fe‐Mg spinel. Zr‐in‐rutile minimum temperatures suggest 〉730°C for this event, which may correlate to rutile‐forming granulite facies metamorphism in other Grenvillian‐aged basement rocks in Mexico and northern South America. A younger generation of baddeleyite exsolution occurred during post‐peak cooling of coarse‐grained rutile, reflected in rimward Zr depletion and formation of discontinuous baddeleyite coronas. Baddeleyite around rutile was then transformed into zircon possibly during subsequent metamorphism at c. 920 or 620 Ma, resulting from syn‐kinematic and contact metamorphism, respectively. Regional metamorphism at c. 450 and 250 Ma extensively overprinted the existing zircon population, especially during the Triassic event, as suggested by a significant presence of zircon with this age. Nearly pristine baddeleyite occurring interstitial to ilmenite yielded an isochron age of c. 232 Ma according to in situ U–Pb secondary ion mass spectrometry (SIMS), suggesting either formation during metamorphic peak conditions or post‐peak cooling. Zircon with ages of c. 80–100 Ma in anorthosite is identified for the first time within the CMC and coincides with cooling ages of c. 100 Ma for coarse‐grained rutile. This age is similar to those of rocks occurring ~200 km further to the east in Guatemala, which are also bounded to the Polochic fault system but overprinted by eclogite facies metamorphism. A high‐pressure event in the southern CMC after 200 Ma, however, is presently unsupported. Although the abundance of rutile and ilmenite is unusually high in the CMC anorthosite assemblage compared with common igneous rocks, the reactions documented here nonetheless stress the importance of these phases for generating Zr‐bearing accessory minerals over a wide range of metamorphic conditions.
    Description: Consejo Nacional de Ciencia y Tecnología (CONACYT) http://dx.doi.org/10.13039/501100003141
    Description: Deutsche Forschungsgemeinschaft (DFG)
    Keywords: ddc:549 ; Diffusion ; SIMS ; Srilankite ; Ti‐Fe deposits ; Ti‐in‐zircon ; Zr‐in‐rutile
    Language: English
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    Jovian Auroral Electron Precipitation Budget—A Statistical Analysis of Diffuse, Mono‐Energetic, and Broadband Auroral Electron Distributions (2022)
    Details
    Publication Date: 2023-01-13
    Description: Recent observations by the Juno spacecraft have shown that electrons contributing to Jupiter's main auroral emission appear to be frequently characterized by broadband electron distributions, but also less often mono‐energetic electron distributions are observed as well. In this work, we quantitatively derive the occurrence rates of the various electron distributions contributing to Jupiter's aurora. We perform a statistical analysis of electrons measured by the JEDI‐instrument within 30–1,200 keV from Juno's first 20 orbits. We determine the electron distributions, either pancake, field‐aligned, mono‐energetic, or broadband, through energy and pitch angles to associate various acceleration mechanisms. The statistical analysis shows that field‐aligned accelerated electrons at magnetic latitudes greater than 76° are observed in 87.6% ± 7.2% of the intervals time averaged over the dipole L‐shells according the main oval. Pancake distributions, indicating diffuse aurora, are prominent at smaller magnetic latitudes (〈76°) with an occurrence rate of 86.2% ± 9.6%. Within the field‐aligned electron distributions, we see broadband distributions 93.0% ± 3.8% of the time and a small fraction of isolated mono‐energetic distribution structures 7.0% ± 3.8% of the time. Furthermore, these occurrence statistics coincide with the findings from our energy flux statistics regarding the electron distributions. Occurrence rates thus also characterize the overall energetics of the different distribution types. This study indicates that stochastic acceleration is dominating the auroral processes in contrast to Earth where the discrete aurora is dominating.
    Description: Plain Language Summary: With the Juno spacecraft arriving in the magnetosphere of Jupiter, first flyby particle measurements have changed the knowledge about the developing process of Jupiter's intense aurora. The observations of auroral particles show a stochastic behavior rather than a preference for specific energy. Our statistical analysis of the first 20 flybys at Jupiter compares the occurrence of different particle distributions and highlights the importance of different generation theories for Jupiter's aurora. A generation via stochastic rather than mono‐energetic behavior is deduced and supports previous observations.
    Description: Key Points: We present a statistical study of Jupiter's auroral electrons within 30–1,200 keV based on Juno's first 20 perijoves. Broadband electron distributions dominates Jupiter's main auroral zone as they are observed in 93% ± 3% of the intervals studied here. Dominance of broadband distributions underlines the importance of a turbulent or stochastic acceleration process.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Universität zu Köln http://dx.doi.org/10.13039/501100008001
    Description: https://lasp.colorado.edu/home/mop/files/2015/02/CoOrd_systems7.pdf
    Description: https://pds-ppi.igpp.ucla.edu/mission/JUNO/JNO/JEDI
    Description: https://lasp.colorado.edu/home/mop/files/2020/04/20190412_Imai_MagFootReader_UIowa_rev.pdf
    Keywords: ddc:523 ; auroral precipitation budget ; particle distribution ; Jupiter ; Juno
    Language: English
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    Drought Conditions Enhance Groundwater Table Fluctuations Caused by Hydropower Plant Management (2022)
    Details
    Publication Date: 2023-01-13
    Description: Management of hydropower plants strongly influences streamflow dynamics and hence the interaction between surface water and groundwater. As dam operations cause variations in river stages, these can result in changes in the groundwater level at multiple temporal scales. In this work, we study the case of an Alpine aquifer, where weekly fluctuations are particularly pronounced. We consider an area with four river reaches differently impacted by reservoir operations and investigate the influence of these rivers on the common aquifer. Using continuous wavelet transform and wavelet coherence analysis, we show that weekly fluctuations in the groundwater table are particularly pronounced in dry years, in particular in the winter season, although the area of the aquifer impacted by dam operations remains almost unchanged. We thus observe that in Alpine catchments, surface water‐groundwater interaction is sensitive to the conditions determined by a specific hydrological year. We also investigate the influences of the river‐aquifer water fluxes and show that under dry conditions hydropeaking mainly affects their temporal dynamics. Our observations have significant consequences for predicting nutrient and temperature dynamics/regimes in river‐aquifer systems impacted by hydropower plant management.
    Description: Plain Language Summary: The operation of hydropower plants affects the water level in the downstream part of the river, which in turn can alter the groundwater level. In this work, we study an Alpine aquifer crossed by rivers differently impacted by hydropower production. We use statistical tools to analyze the interaction between the rivers and the groundwater, and observe that this interaction is sensitive to the conditions of the hydrological year, such as dry periods.
    Description: Key Points: Wavelet power spectrum and coherence analysis is used to study river‐aquifer interactions under dam operations in an Alpine catchment. The impact of reservoir operations on the aquifer is strongest under low flow conditions but the area impacted shows little variation. Under low flow conditions, dam operations considerably influence the frequency of the water exchange between rivers and aquifer.
    Description: Consejo Nacional de Ciencia y Tecnología http://dx.doi.org/10.13039/501100003141
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Consejo Veracruzano de Investigación Científica y Desarrollo Tecnológico
    Description: https://doi.org/10.17632/97jchhz4s8.2
    Keywords: ddc:551 ; surface water‐groundwater interaction ; hydropower ; managed rivers ; groundwater modeling
    Language: English
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    Record summers in Europe: Variations in drought and heavy precipitation during 1901–2018 (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-13
    Description: During the last 20 years some very hot and dry summers affected Europe, resulting in regionally record‐breaking high temperature or low precipitation values. Long‐term changes of such extremely hot and dry summers are of great relevance for our society, as they are connected with manifold negative impacts on human society, natural ecosystems, and diverse economic sectors. Long‐term variations in drought and five record drought summer half years are studied based on 63 stations across Europe with high‐quality precipitation and temperature time series spanning the period 1901–2018. Eight drought indices are deployed to analyse drought intensity, frequency, and duration; four of them purely precipitation‐based and four integrating potential evapotranspiration in the computation. Additionally, three heavy precipitation indices and simultaneous increases in drought and heavy precipitation are studied. The five driest summer half years over Europe are identified (1947, 2018, 2003, 1921, and 1911). They are analysed by aggregating eight drought indices into the aggregated drought evaluation index (ADE) for five subregions. The ADE shows increasing summer drought conditions over most of Europe, except for some stations in northern Europe. The increase in drought conditions during the warm part of the year is particularly pronounced for indices integrating evapotranspiration in their definition. At the same time, the intensity of heavy precipitation events shows a positive trend, as well as an increased contribution to total precipitation. Several stations in central Europe show simultaneously increasing drought conditions and increasing heavy precipitation events. This increases the risks connected with precipitation extremes.
    Description: Drought and heavy precipitation trends are studied for selected stations with long time series. Both extreme events are related to specific impacts on different economic sectors and thus society. Stations that simultaneously show increasing trends in drought and heavy precipitation mainly occur in central Europe. This indicates a probably higher exposure to these risks in central Europe as well as a demand for broader adaptation options in this region.
    Keywords: ddc:551.6 ; climate indices ; climate variability and change ; dry periods ; mRAI ; WBAI
    Language: English
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    Earthquake Rupture on Multiple Splay Faults and Its Effect on Tsunamis (2022)
    Details
    Publication Date: 2023-01-19
    Description: Detailed imaging of accretionary wedges reveals splay fault networks that could pose a significant tsunami hazard. However, the dynamics of multiple splay fault activation during megathrust earthquakes and the consequent effects on tsunami generation are not well understood. We use a 2‐D dynamic rupture model with complex topo‐bathymetry and six curved splay fault geometries constrained from realistic tectonic loading modeled by a geodynamic seismic cycle model with consistent initial stress and strength conditions. We find that all splay faults rupture coseismically. While the largest splay fault slips due to a complex rupture branching process from the megathrust, all other splay faults are activated either top down or bottom up by dynamic stress transfer induced by trapped seismic waves. We ascribe these differences to local non‐optimal fault orientations and variable along‐dip strength excess. Generally, rupture on splay faults is facilitated by their favorable stress orientations and low strength excess as a result of high pore‐fluid pressures. The ensuing tsunami modeled with non‐linear 1‐D shallow water equations consists of one high‐amplitude crest related to rupture on the longest splay fault and a second broader wave packet resulting from slip on the other faults. This results in two episodes of flooding and a larger run‐up distance than the single long‐wavelength (300 km) tsunami sourced by the megathrust‐only rupture. Since splay fault activation is determined by both variable stress and strength conditions and dynamic activation, considering both tectonic and earthquake processes is relevant for understanding tsunamigenesis.
    Description: Plain Language Summary: In subduction zones, where one tectonic plate moves beneath another, earthquakes can occur on many different faults. Splay faults are relatively steep faults that branch off the largest fault (the megathrust) in a subduction zone. As they are steeper than the megathrust, the same amount of movement on them could result in more vertical displacement of the seafloor. Therefore, splay faults are thought to play an important role in the generation of tsunamis. Here, we use computer simulations to study if an earthquake can break multiple splay faults at once and how this affects the resulting tsunami. We find that multiple splay faults can indeed fail during a single earthquake due to the stress changes from trapped seismic waves, which promote rupture on splay faults. Rupture on splay faults results in larger seafloor displacements with smaller wavelengths, so the ensuing tsunami is bigger and results in two main flooding episodes at the coast. Our results show that it is important to consider rupture on splay faults when assessing tsunami hazard.
    Description: Key Points: Multiple splay faults can be activated during a single earthquake by megathrust slip and dynamic stress transfer due to trapped waves. Splay fault activation is facilitated by their favorable orientation with respect to the local stress field and their closeness to failure. Long‐term geodynamic stresses and fault geometries affect dynamic splay fault rupture and the subsequent tsunami.
    Description: Volkswagen Foundation (VolkswagenStiftung) http://dx.doi.org/10.13039/501100001663
    Description: Royal Society (The Royal Society) http://dx.doi.org/10.13039/501100000288
    Description: EC | H2020 | H2020 Priority Excellent Science | H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Description: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Description: https://github.com/TUM-I5/SWE
    Description: https://doi.org/10.5281/zenodo.6969455
    Keywords: ddc:551 ; earthquake ; tsunami ; subduction zone ; dynamic rupture ; splay fault ; numerical modeling
    Language: English
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    Nutrient and Silicon Isotope Dynamics in the Laptev Sea and Implications for Nutrient Availability in the Transpolar Drift (2022)
    Details
    Publication Date: 2023-01-19
    Description: Realistic prediction of the near‐future response of Arctic Ocean primary productivity to ongoing warming and sea ice loss requires a mechanistic understanding of the processes controlling nutrient bioavailability. To evaluate continental nutrient inputs, biological utilization, and the influence of mixing and winter processes in the Laptev Sea, the major source region of the Transpolar Drift (TPD), we compare observed with preformed concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP), silicic acid (DSi), and silicon isotope compositions of DSi (δ30SiDSi) obtained for two summers (2013 and 2014) and one winter (2012). In summer, preformed nutrient concentrations persisted in the surface layer of the southeastern Laptev Sea, while diatom‐dominated utilization caused intense northward drawdown and a pronounced shift in δ30SiDSi from +0.91 to +3.82‰. The modeled Si isotope fractionation suggests that DSi in the northern Laptev Sea originated from the Lena River and was supplied during the spring freshet, while riverine DSi in the southeastern Laptev Sea was continuously supplied during the summer. Primary productivity fueled by river‐borne nutrients was enhanced by admixture of DIN‐ and DIP‐rich Atlantic‐sourced waters to the surface, either by convective mixing during the previous winter or by occasional storm‐induced stratification breakdowns in late summer. Substantial enrichments of DSi (+240%) and DIP (+90%) beneath the Lena River plume were caused by sea ice‐driven redistribution and remineralization. Predicted weaker stratification on the outer Laptev Shelf will enhance DSi utilization and removal through greater vertical DIN supply, which will limit DSi export and reduce diatom‐dominated primary productivity in the TPD.
    Description: Plain Language Summary: Ongoing warming and sea ice loss in the Arctic Ocean may significantly impact biological productivity, which is mainly controlled by light and nutrient availability. To investigate nutrient inputs from land, biological utilization, and the influence of water mass mixing and winter processes on the nutrient distributions, we measured nutrient concentrations and silicon isotopes in the Laptev Sea. We found high concentrations in the southeastern Laptev Sea in agreement with nutrient inputs from the Lena River. Toward the northern Laptev Sea, nutrient concentrations decreased in the surface layer and the silicon isotope signatures shifted to heavier values, consistent with nutrient utilization by phytoplankton. In contrast to the depleted surface layer, the bottom layer beneath the Lena River plume was strongly enriched in some nutrients, which we attribute to different physical and biogeochemical processes. These observations are important for our understanding of nutrient bioavailability in the Laptev Sea and the Transpolar Drift (TPD), which is a surface current that connects the Laptev Sea with the central Arctic Ocean and the Fram Strait. The changing hydrography of the Laptev Sea will likely cause a decrease in silicic acid concentrations and thus a reduction in nutrient export and diatom‐dominated primary productivity in the TPD.
    Description: Key Points: Surface dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), silicic acid (DSi), and Si isotope dynamics are controlled by marine and riverine inputs and uptake by phytoplankton. Strong DIP and DSi enrichments beneath the Lena River plume are due to sea ice‐driven nutrient redistribution and remineralization. Enhanced DSi utilization in the Laptev Sea will lead to a reduced diatom‐dominated primary productivity in the Transpolar Drift.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Ocean Frontier Institute http://dx.doi.org/10.13039/501100010784
    Description: Canada First Research Excellence Fund http://dx.doi.org/10.13039/501100010785
    Description: https://doi.pangaea.de/10.1594/PANGAEA.931257
    Description: https://doi.pangaea.de/10.1594/PANGAEA.931240
    Description: https://doi.pangaea.de/10.1594/PANGAEA.931209
    Description: https://doi.pangaea.de/10.1594/PANGAEA.938259
    Keywords: ddc:577.7 ; Arctic Ocean ; Laptev Sea ; transpolar drift ; nutrients ; silicon isotopes ; diatoms
    Language: English
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    Climate Change, Pollution, Deforestation, and Mental Health: Research Trends, Gaps, and Ethical Considerations (2022)
    Details
    Publication Date: 2023-01-19
    Description: Climate change, pollution, and deforestation have a negative impact on global mental health. There is an environmental justice dimension to this challenge as wealthy people and high‐income countries are major contributors to climate change and pollution, while poor people and low‐income countries are heavily affected by the consequences. Using state‐of‐the art data mining, we analyzed and visualized the global research landscape on mental health, climate change, pollution and deforestation over a 15‐year period. Metadata of papers were exported from PubMed®, and both relevance and relatedness of terms in different time frames were computed using VOSviewer. Co‐occurrence graphs were used to visualize results. The development of exemplary terms over time was plotted separately. The number of research papers on mental health and environmental challenges is growing in a linear fashion. Major topics are climate change, chemical pollution, including psychiatric medication in wastewater, and neurobiological effects. Research on specific psychiatric syndromes and diseases, particularly on their ethical and social aspects is less prominent. There is a growing body of research literature on links between mental health, climate change, pollution, and deforestation. This research provides a graphic overview to mental healthcare professionals and political stakeholders. Social and ethical aspects of the climate change‐mental health link have been neglected, and more research is needed.
    Description: Plain Language Summary: Climate change, deforestation, and pollution are having a major effect on mental health all around the world. Yet there are huge disparities on how these negative consequences affect people within and between countries. We analyzed large databases of research articles using digital tools (data mining) to uncover the direction of scientific research and areas that have received less scholarly attention. While research linking climate change to mental health issues is expanding, a detailed examination of the social justice dimension of how climate change and pollution are affecting the different groups of people is still relatively scarce. We provide a graphical overview of the most important research keywords of the last 15 years.
    Description: Key Points: Climate change, pollution, and deforestation threaten global mental health and need to be addressed as a mental health issue. Data mining can help to uncover trends and gaps in research. Mental health research on climate change and pollution is growing, while research linking these to environmental injustice is less prominent.
    Description: Clinician Scientist Programme of the Medical Faculty of Ulm University
    Keywords: ddc:363.7 ; climate change ; mental health ; data mining ; medical ethics ; contamination ; environmental justice
    Language: English
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    Non‐Tidal Background Modeling for Satellite Gravimetry Based on Operational ECWMF and ERA5 Reanalysis Data: AOD1B RL07 (2022)
    Details
    Publication Date: 2023-01-19
    Description: The Atmosphere and Ocean De‐Aliasing Level‐1B (AOD1B) product provides a priori information about temporal variations in the Earth's gravity field induced by non‐tidal circulation processes in atmosphere and ocean. It is routinely applied as a background model in the Gravity Recovery and Climate Experiment (GRACE)/GRACE Follow‐On (GRACE‐FO) satellite gravimetry data processing. We here present three new datasets in preparation for the upcoming release RL07 of AOD1B, that are based on either the global ERA5 reanalysis or the ECMWF operational data together with simulations from the Max‐Planck‐Institute for Meteorology general circulation model forced consistently with the fields of the same atmospheric data set. The oceanic simulations newly include an updated bathymetry around Antarctica including cavities under the ice shelves, the explicit implementation of the feedback effects of self‐attraction and loading to ocean dynamics as well as a refined harmonic tidal analysis. Comparison to the current release of AOD1B in terms of GRACE‐FO K‐band range‐acceleration pre‐fit residuals, LRI line‐of‐sight gravity differences and band‐pass filtered altimetry data reveals an overall improvement in the representation of the high‐frequency mass variability. Potential benefits of enhancing the temporal resolution remain inconclusive so that the upcoming release 07 will be sampled again every 3 hr.
    Description: Plain Language Summary: Satellite gravimetry missions such as the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow‐On (GRACE‐FO), which play a vital role in the monitoring of the Earth's mass transports, require a priori background information on the high‐frequency mass variations which can not be resolved by the monthly gravity solutions. The Atmosphere and Ocean De‐Aliasing Level‐1B (AOD1B) data product provides the required background information for non‐tidal high‐frequency mass changes in the atmosphere and oceans. However, the accurate representation of these mass variations remains challenging and deficiencies in the background models have a significant impact on the overall gravity field errors. Thus, we here present three new datasets in preparation for an upcoming release of AOD1B (RL07). The datasets improve over previous releases by incorporating the effects of the self attraction and solid earth deformation caused by anomalous water masses (SAL), an improved representation of the bathymetry and atmospheric forcing around Antarctica, making use of the new ERA5 atmospheric reanalysis as well as an updated estimation and subtraction of atmospherically induced tidal signals. We compare the new data to the previous release of AOD1B using microwave‐ and laser‐ranging data from GRACE‐FO as well as Jason‐3 altimetry data and show a global improvement in the representation of high‐frequency mass changes.
    Description: Key Points: Atmospheric mass variability from ECMWF’s latest global reanalysis ERA5 is discussed. Ocean response from Max‐Planck‐Institute for Meteorology Ocean Model includes feedback of self‐attraction and loading. Applicable for Gravity Recovery and Climate Experiment (GRACE), GRACE Follow‐On, and legacy data from SLR satellites.
    Description: Deutsche Forschungsgemeinschaft, DFG http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5880/GFZ.1.3.2022.003
    Keywords: ddc:526.7 ; AOD1B RL07 ; GRACE ; ERA5 ; self‐attraction and loading ; satellite gravimetry
    Language: English
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    A Seismic Approach to Flood Detection and Characterization in Upland Catchments (2022)
    Details
    Publication Date: 2023-01-19
    Description: About 10% of Europe's surface area is prone to rapid flooding of rivers confined in valleys. The devastating potential of such floods is exacerbated by the deficits of existing gauging networks, including low station densities and recording frequencies, and lack of information beyond stage height. Here, we use seismic data of the July 2021 Ahrtal flood, Germany, to extract information to complement sparse hydrometric data, and to reconstruct the rapid evolution of this fatal event. We show that a seismic station can deliver essential flood metrics such as magnitude, propagation velocity and debris transport rate. These seismic products provide high resolution insight to the non‐linear flood behavior. We argue that an approach combining distributed low‐cost seismometers with existing seismic stations, can provide important real time data on future catastrophic floods and associated hazards in upland catchments, offering precious response time also in currently ungauged landscapes.
    Description: Plain Language Summary: Rapidly evolving floods are a major hazard for 10% of European landscapes. They are hard to adequately detect and describe by the classic gauge station scheme, but seismic sensors provide a valuable alternative to this difficulty. A seismometer can sense a flood like the devastating one that hit the Ahr valley, Germany, in July 2021 up to 1.5 km away. The seismic footprint of the flood allows to provide information on flood magnitude, velocity and trajectory at sub‐minute resolution and at near real time. We show how this new approach can be utilized for future flood protection.
    Description: Key Points: Seismic sensing of valley confined floods improves classic detection approaches. Near‐real time information on flood magnitude, trajectory, and velocity. Gate keeper seismometer networks can improve flood risk management in Europe.
    Description: GFZ German Research Centre for Geosciences
    Description: Helmholtz Centre Potsdam—GFZ German Research Centre for Geosciences http://dx.doi.org/10.13039/501100010956
    Description: German Research Foundation
    Keywords: ddc:622.1592 ; hazard ; realtime warning ; flash flood ; seismic
    Language: English
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    Magmatic Activity and Dynamics of Melt Supply of Volcanic Centers of Ultraslow Spreading Ridges: Hints From Local Earthquake Tomography at the Knipovich Ridge (2022)
    Details
    Publication Date: 2023-01-19
    Description: Along ultraslow spreading ridges melt is distributed unequally, but melt focusing guides melt away from amagmatic segments toward volcanic centers. An interplay of tectonism and magmatism is thought to control melt ascent, but the detailed process of melt extraction is not yet understood. We present a detailed image of the seismic velocity structure of the Logachev volcanic center and adjacent region along the Knipovich Ridge. With travel times of P‐ and S‐waves of 3,959 earthquakes we performed a local earthquake tomography. We simultaneously inverted for source locations, velocity structure and the Vp/Vs‐ratio. An extensive low velocity anomaly coincident with high Vp/Vs‐ratios 〉1.9 lies underneath the volcanic center at depths of 10 km below sea level in an aseismic area. More shallow, tightly clustered earthquake swarms connect the anomaly to a shallow anomaly with high Vp/Vs‐ratio beneath the basaltic seafloor. We consider the deep low‐velocity anomaly to represent an area of partial melt from which melts ascent vertically to the surface and northwards into the adjacent segment. By comparing tomographic studies of the Logachev and Southwest Indian Ridge Segment‐8 volcano we conclude that volcanic centers of ultraslow spreading ridges host spatially confined, circular partial melt areas below 10 km depth, in contrast to the shallow extended melt lenses along fast spreading ridges. Lateral feeding over distances of 35 km is possible at orthogonal spreading segments, but limited at the obliquely spreading Knipovich Ridge.
    Description: Plain Language Summary: Mid‐ocean ridges mark the tectonic plate boundaries, where the plates drift apart. Fresh magma rises into the gap and builds new seafloor. The slower the plates drift apart, the less magma is present underneath the ridge. At very slow spreading ridges there is not enough magma to build new seafloor along the entire length of the ridge. Rather, melt is guided toward individual volcanic centers spaced at about 100 km, where melt accumulates and ascents. In our study we try to find melt storage areas and ascent paths of such a volcanic center. With velocities of different seismic wave types from earthquakes we map the velocity structure of the area underneath the major Logachev volcanic center. Lower velocities indicate an area partly including melt at depths of more than 10 km, far deeper than at mid‐ocean ridges with sufficient melt supply. From the deep magma reservoir, many earthquake swarms map the long ascent path of melt to the surface. The interplay of magmatic and tectonic activity is important here. In a comparison with results from another volcanic center, we find that lateral magma feeding is possible in orthogonal spreading, but limited in oblique spreading, as at the Knipovich Ridge.
    Description: Key Points: Active volcanic centers at ultraslow spreading ridges host deeper and more confined partial melt areas than faster spreading ridges. Earthquake swarms delineate melt ascent paths from the partial melt area to the surface. Lateral feeding at shallow depths into subordinate segments is prevented by ridge obliquity.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.22 ; ultraslow spreading ; Knipovich Ridge ; local earthquake tomography ; seismicity ; mid‐ocean ridge ; partial melt area
    Language: English
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    Modeling Lithospheric Thickness Along the Conjugate South Atlantic Passive Margins Implies Asymmetric Rift Initiation (2022)
    Details
    Publication Date: 2023-01-19
    Description: The lithospheric architecture of passive margins is crucial for understanding the tectonic processes that caused the breakup of Gondwana. We highlight the evolution of the South Atlantic passive margins by a simple thermal lithosphere‐asthenosphere boundary (LAB) model based on onset and cessation of rifting, crustal thickness, and stretching factors. We simulate lithospheric thinning and select the LAB as the T = 1,330°C isotherm, which is calculated by 1D advection and diffusion. Stretching factors and margin geometry are adjusted to state‐of‐the‐art data sets, giving a thermal LAB model that is especially designed for the continental margins of the South Atlantic. Our LAB model shows distinct variations along the passive margins that are not imaged by global LAB models, indicating different rifting mechanisms. For example, we model up to 200 km deep lithosphere in the South American Santos Basin and shallow lithosphere less than 60 km in the Namibe Basin offshore Africa. These two conjugate basins reflect a strong asymmetry in LAB depth that resembles variations in margin width. In a Gondwana reconstruction, we discuss these patterns together with seismic velocity perturbations for the Central and Austral Segments of the margins. The shallow lithosphere in the Namibe Basin correlates with signatures of the Angola Dome, attributed to epeirogenic uplift in the Neogene, suggesting an additional component of post‐breakup lithospheric thinning.
    Description: Plain Language Summary: Passive margins mark the transition zone from a continent to the ocean without being an active boundary of tectonic plates. They are typical for all continents on the globe. In the South Atlantic, the passive margins are located adjacent to the eastern coastline of South America and the western coastline of Africa. Studying the architecture of passive margins is essential for understanding plate tectonic history of the earth because they define how the continents once fitted together and how they broke apart. Passive margin segments on opposite sides of an ocean form so called conjugate margin pairs. Most geophysical studies of passive margins focus on the first few kilometers under the surface. However, their deeper extension to the base of the rigid shell of the earth, known as lithospheric thickness, is to a large extent unknown. Based on a simple temperature model, we find that the lithospheric thickness is highly variable and shows large variations along the South Atlantic passive margins. These differences are associated with the extension of conjugate margin pairs: where one margin is narrower than the conjugate, its lithospheric thickness is greater. This asymmetry indicates that the geodynamic processes, causing the breakup of the two continents, must have been asymmetric as well. Offshore Angola, the lithosphere is modeled shallow and matches with relatively young rock signatures. This suggests additional tectonic activity on the African side after the breakup between the two continents occurred.
    Description: Key Points: A simple thermal lithosphere‐asthenosphere boundary (LAB) model for the South Atlantic passive margins has been developed. The LAB model shows distinct variations along the margins that correlate with margin widths. Conjugate margin pairs reflect an asymmetry in LAB depth patterns that are locally related to post‐breakup lithospheric thinning.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5880/GFZ.1.3.2020.006
    Description: https://www.earthbyte.org/webdav/ftp/Data_Collections/Muller_etal_2019_Tectonics/
    Description: https://doi.org/10.5281/zenodo.7074000
    Description: https://earthbyte.org/webdav/ftp/Data_Collections/Haas_etal_2022_Tectonics/
    Keywords: ddc:551.13 ; passive margins ; South Atlantic ; thermal LAB ; rift asymmetry ; Gondwana
    Language: English
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    Surface Wave and Roller Dissipation Observed With Shore‐Based Doppler Marine Radar (2022)
    Details
    Publication Date: 2023-01-19
    Description: Surface wave energy and dissipation are observed across the surf zone. Utilizing the concept of surface rollers, a new scaling is introduced to obtain the energy flux and dissipation related to rollers from Doppler velocities measured by a shore‐based X‐band marine radar. The dissipation of wave energy and hence the transformation of the incoming wave height (or energy) is derived using the coupled wave and roller energy balance equations. Results are compared to in‐situ wave measurements obtained from a wave rider buoy and two bottom mounted pressure wave gauges. A good performance in reproducing the significant wave height is found yielding an overall root‐mean‐square error of 0.22 m and a bias of −0.12 m. This is comparable to the skill of numerical wave models. In contrast to wave models, however, the radar observations of the wave and roller energy flux and dissipation neither require knowledge of the bathymetry nor the incident wave height. Along a 1.5 km long cross‐shore transect on a double‐barred, sandy beach in the southern North Sea, the highest dissipation rates are observed at the inner bar over a relatively short distance of less than 100 m. During the peak of a medium‐severe storm event with significant wave heights over 3 m, about 50% of the incident wave energy flux is dissipated at the outer bar.
    Description: Plain Language Summary: Ocean waves are carrying a large amount of mechanical energy which they have gained from the wind blowing over the ocean surface. At the coast this energy supply generates strong water motions, creates forces on coastal structures, moves sand, and can cause coastal erosion. It is therefore important to know when, where, and to what extent wave energy is reduced under different environmental conditions. The majority of the energy is removed by wave breaking. However, this process is still not completely understood which is partly due to fact that it is difficult to observe. This is particularly the case during storm conditions when it is very complicated to install and recover measurement equipment in the ocean. The present work describes a methodology to obtain such measurements using a special radar device which is installed at the beach; hence, it is not being impacted by harsh wave conditions. This approach will enable scientists to perform long‐term monitoring of wave breaking thus opening new opportunities to study beach processes and coastal changes.
    Description: Key Points: high‐resolution observations of surface wave and roller dissipation as well as the transformation of wave height across the surf zone. the concept of surface rollers is applied to shore‐based X‐band Doppler radar data. in storm conditions, 50% of the wave energy is dissipated at a submerged outer sandbar, but strongest dissipation occurs further inshore.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: http://codm.hzg.de/codm
    Description: https://doi.org/10.1594/683PANGAEA.898407
    Description: https://doi.org/10.1594/PANGAEA.942014
    Description: https://doi.org/10.5281/zenodo.5787131
    Keywords: ddc:551.46 ; wave breaking ; X‐band radar ; roller concept ; close‐range remote sensing ; energy dissipation ; wave transformation
    Language: English
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    Leveraging Governance Performance to Enhance Climate Resilience (2022)
    Details
    Publication Date: 2023-01-19
    Description: Enhancing the resilience of complex social‐ecological systems (SES) to climate change requires transformative changes. Yet, there are knowledge gaps on how best to achieve transformation. In this study, we present an approach for assessing governance performance in SES and identifying leverage points to ultimately enhance climate resilience. The approach combines three different methods including a capital approach framework, fuzzy cognitive mapping, and a leverage points analysis. Using a coastal case‐study in Algoa Bay, South Africa, the performance of governance processes contributing to different forms of capital is assessed. Subsequently, leverage points ‐ where a small shift may lead to transformative changes in the system as a whole ‐ are identified based on measures of centrality and performance. Results suggest that a range of leverage points can improve governance performance and therefore climate resilience in the case‐study. Leverage points include improving (a) support from the provincial government; (b) priority given to climate change in the integrated development plan; (c) frequency of collaborations; (d) participation in the implementation of climate action plans; (e) allocation of funding to climate change actions; (f) the overall level of preparedness in terms of staff with relevant expertise; (g) public awareness and understanding of climate change. The approach can also be used to analyze and model the relations and interactions between capitals. The study advances methodological and theoretical knowledge on the identification of leverage points for enabling transformations toward climate resilience and broader sustainability goals in SES.
    Description: Plain Language Summary: Climate change has severe impacts on both people and nature. Enhancing the ability to persist and adapt to climate change requires transformative governance of social‐ecological systems. However, more knowledge is required on how to enable such transformations. In this paper, we present an approach to measure the performance of different governance processes, such as decisions and actions for climate change adaptation made by public and governmental organizations. The approach aims to identify key processes, where a small intervention may improve overall performance for climate change adaptation, and therefore transformation. We apply the approach in a real‐world example in Algoa Bay, South Africa. Results suggest that different processes in the case‐study can be changed in order to enhance the ability to persist and adapt to climate change. This includes seven actions: (a) more support from governmental organizations; (b) greater priority given to climate change in relevant policies; (c) increasing the frequency of interactions between organizations; (d) enhancing the participation in the implementation of climate action plans; (e) better allocation of funding to climate change actions; (f) training staff within organizations to enhance their climate expertise; (g) improving public awareness and understanding of climate change.
    Description: Key Points: The study presents an approach for assessing governance performance and identifying leverage points in social‐ecological systems. The approach combines three different methods: a capital approach framework, fuzzy cognitive mapping, and a leverage points analysis. The study advances methodological and theoretical knowledge on how to operationalize transformation toward climate resilience.
    Description: Helmholtz‐Zentrum Hereon
    Description: Western Indian Ocean Marine Science Association http://dx.doi.org/10.13039/501100009106
    Description: https://doi.org/10.6084/m9.figshare.20732788
    Keywords: ddc:551.6 ; social‐ecological systems ; climate change adaptation ; transformation ; leverage points ; coastal governance ; adaptive capacity
    Language: English
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    Towards a more comprehensive assessment of the intensity of historical European heat waves (1979–2019) (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-19
    Description: Europe has been affected by record‐breaking heat waves in recent decades. Using station data and a gridded reanalysis as input, four commonly used heat wave indices, the heat wave magnitude index daily (HWMId), excess heat factor (EHF), wet‐bulb globe temperature (WBGT) and universal thermal climate index (UTCI), are computed. The extremeness of historical European heat waves between 1979 and 2019 using the four indices and different metrics is ranked. A normalisation to enable the comparison between the four indices is introduced. Additionally, a method to quantify the influence of the input parameters on heat wave magnitude is introduced. The spatio‐temporal behaviour of heat waves is assessed by spatial–temporal tracking. The areal extent, large‐scale intensity and duration are visualized using bubble plots. As expected, temperature explains the largest variance in all indices, but humidity is nearly as important in WBGT and wind speed plays a substantial role in UTCI. While the 2010 Russian heat wave is by far the most extreme event in duration and intensity in all normalized indices, the 2018 heat wave was comparable in size for EHF, WBGT and UTCI. Interestingly, the well‐known 2003 central European heat wave was only the fifth and tenth strongest in cumulative intensity in WBGT and UTCI, respectively. The June and July 2019 heat waves were very intense, but short‐lived, thus not belonging to the top heat waves in Europe when duration and areal extent are taken into account. Overall, the proposed normalized indices and the multi‐metric assessment of large‐scale heat waves allow for a more robust description of their extremeness and will be helpful to assess heat waves worldwide and in climate projections.
    Description: Europe has been affected by record‐breaking heat waves in recent decades. Using station data and a gridded reanalysis, the extremeness of European heat waves between 1979 and 2019 is ranked using four indices: heat wave magnitude index daily (HWMId), excess heat factor (EHF), wet‐bulb globe temperature (WBGT) and universal thermal climate index (UTCI). In order to assess heatwaves worldwide and in climate projections, the spatial extent, large‐scale intensity and duration of heatwaves are visualized using bubble plots.
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Karlsruher Institut für Technologie http://dx.doi.org/10.13039/100009133
    Keywords: ddc:551.5 ; duration ; heat wave ; indices ; intensity ; large‐scale ; spatial extent
    Language: English
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    The Influence of Grain Size Distribution on Laboratory‐Generated Volcanic Lightning (2022)
    Details
    Publication Date: 2023-01-20
    Description: Over the last decades, remote observation tools and models have been developed to improve the forecasting of ash‐rich volcanic plumes. One challenge in these forecasts is knowing the properties at the vent, including the mass eruption rate and grain size distribution (GSD). Volcanic lightning is a common feature of explosive eruptions with high mass eruption rates of fine particles. The GSD is expected to play a major role in generating lightning in the gas thrust region via triboelectrification. Here, we experimentally investigate the electrical discharges of volcanic ash as a function of varying GSD. We employ two natural materials, a phonolitic pumice and a tholeiitic basalt (TB), and one synthetic material (soda‐lime glass beads [GB]). For each of the three materials, coarse and fine grain size fractions with known GSDs are mixed, and the particle mixture is subjected to rapid decompression. The experiments are observed using a high‐speed camera to track particle‐gas dispersion dynamics during the experiments. A Faraday cage is used to count the number and measure the magnitude of electrical discharge events. Although quite different in chemical composition, TB and GB show similar vent dynamics and lightning properties. The phonolitic pumice displays significantly different ejection dynamics and a significant reduction in lightning generation. We conclude that particle‐gas coupling during an eruption, which in turn depends on the GSD and bulk density, plays a major role in defining the generation of lightning. The presence of fines, a broad GSD, and dense particles all promote lightning.
    Description: Plain Language Summary: Explosive volcanic eruptions are accompanied by volcanic lightning (VL), which are electrical discharges resulting from particles that become electrically charged during eruption. We investigated experimentally the discharge behavior of three different materials by performing shock‐tube experiments. We used different rocks and analog material. We focused on the abundance of particle sizes smaller 〈10 μm (very fine ash) by testing individual grain size fractions mixed with coarser grains. The jet behavior was recorded by a high‐speed camera. We find that the presence of very fine particles has a major influence on the probability to produce electrical discharges within the particle‐laden jet. Based on our experiments, more VL is expected when (a) fine ash is abundant, (b) there is a wide grain size distribution, and (c) the particles are dense.
    Description: Key Points: Electrical discharges are generated in experimentally decompressed volcanic ash. The presence of fines (〈10 μm), a broad grain size distribution, and dense particles promote laboratory‐generated volcanic lightning. The coupling of the particles to the jet determines whether an electrical discharge occurs within the jet.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: European Research Council
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: CIFAR Earth 4D
    Keywords: ash ; electric charge ; rapid decompression ; volcanic lightning
    Language: English
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    Seasonal Landslide Activity Lags Annual Precipitation Pattern in the Pacific Northwest (2022)
    Details
    Publication Date: 2023-01-20
    Description: Seasonal variations in landslide activity remain understudied compared to recent advances in landslide early warning at hourly to daily timescales. Here, we learn the seasonal pattern of monthly landslide activity in the Pacific Northwest from five heterogeneous landslide inventories with differing spatial and temporal coverage and reporting protocols combined in a Bayesian multi‐level model. We find that landslide activity is distinctly seasonal, with credible increases in landslide intensity, inter‐annual variability, and probability marking the onset of the landslide season in November. Peaks in landslide probability in January and intensity in February lag the annual peak in mean monthly precipitation and landslide activity is more variable in winter than in summer, when landslides are rare. For a given monthly rainfall, landslide intensity at the season peak in February is up to 10 times higher than at the onset in November, underlining the importance of antecedent seasonal hillslope conditions.
    Description: Plain Language Summary: Better knowing when landslides are likely over the course of the year can reduce landslide risk by improving emergency preparedness. One research challenge is that catalogs of past landslides rarely cover the same areas or time periods, and have been collected in different ways. Here, we use statistical models to estimate monthly landslide activity in the Pacific Northwest. The models are able to combine five different landslide catalogs to make best use of all available information. We find a seasonal pattern in both the average number of landslides in a month and the probability of having any landslides. The landslide season begins in November, when the average number and the probability of landslides increase. The probability of landslides peaks in January and the average number in February, lagging behind winter rainfall peaks by one to two months. While landslides are least likely in summer, their activity is more variable in winter, with some winters bringing hundreds of landslides, and some very few. At the landslide season peak in February, a comparable amount of rain leads to many more landslides than at the onset in November, likely because already wet hillslopes are more prone to failure.
    Description: Key Points: Bayesian inference learns the seasonal pattern of landslide activity in the Pacific Northwest from five combined heterogeneous inventories. Landsliding is distinctly seasonal with highest probability (intensity) in January (February), lagging the annual precipitation peak. Landslide intensity for a given monthly rainfall during peak season in February is up to 10 times higher than at the onset in November.
    Description: DFG RTG NatRiskChange
    Description: https://data.nasa.gov/Earth-Science/Global-Landslide-Catalog/h9d8-neg4
    Keywords: ddc:551.3 ; landslide ; seasonality ; Pacific Northwest ; Bayesian multi‐level models ; logistic regression ; negative binomial regression
    Language: English
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    Constraining Europa's Subsolar Atmosphere With a Joint Analysis of HST Spectral Images and Galileo Magnetic Field Data (2022)
    Details
    Publication Date: 2023-01-20
    Description: We constrain Europa's tenuous atmosphere on the subsolar hemisphere by combining two sets of observations: oxygen emissions at 1,304 and 1,356 Å from Hubble Space Telescope (HST) spectral images and Galileo magnetic field measurements from its closest encounter, the E12 flyby. We describe Europa's atmosphere with three neutral gas species: global molecular (O2) and atomic oxygen (O), and localized water (H2O) present as a near‐equatorial plume and as a stable distribution concentrated around the subsolar point on the moon's trailing hemisphere. Our combined modeling based on the ratio of OI 1,356 to OI 1,304 Å emissions from Roth (2021; https://doi.org/10.1029/2021gl094289) and on magnetic field data allows us to derive constraints on the density and location of O2 and H2O in Europa's atmosphere. We demonstrate that 50% of the O2 and between 50% and 75% of the H2O abundances from Roth (2021; https://doi.org/10.1029/2021gl094289) are required to jointly explain the HST and Galileo measurements. These values are conditioned on a column density of O close to the upper limit of 6 × 1016 m−2 derived by Roth (2021; https://doi.org/10.1029/2021gl094289), and on a strongly confined stable H2O atmosphere around the subsolar point. Our analysis yields column densities of 1.2 × 1018 m−2 for O2, and 1.5 × 1019 to 2.2 × 1019 m−2 at the subsolar point for H2O. Both column densities, however, still lie within the uncertainties of Roth (2021; https://doi.org/10.1029/2021gl094289). Our results provide additional evidence for the existence of a stable H2O atmosphere at Europa.
    Description: Key Points: We combine Hubble Space Telescope spectral images and Galileo magnetometer data to constrain the density and location of water vapor in Europa's atmosphere. We simulate the plasma interaction for the Galileo E12 flyby with a three‐component atmosphere: global O2, stable confined H2O, and a plume. Using 50% of O2 and from 50% to 75% of H2O column densities from Roth (2021) yields magnetic field signatures consistent with both observations.
    Description: European Research Council http://dx.doi.org/10.13039/100010663
    Description: http://doi.org/10.17189/1519667
    Keywords: ddc:523 ; Europa ; Jupiter ; moon‐magnetosphere interaction ; icy moons ; atmosphere
    Language: English
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    The Interconnected Magmatic Plumbing System of the Natron Rift (2022)
    Details
    Publication Date: 2023-01-20
    Description: Understanding the magmatic plumbing system of rift volcanoes is essential when examining the interplay between magmatic and tectonic forces. Recent seismicity, volcanic activity, magma emplacement, and volatile release make the Natron basin the ideal location to study these processes in the East African Rift System. Here, we present the first high‐resolution tomographic imaging of Oldoinyo Lengai volcano and surrounding volcanic systems using attenuation mapping. High scattering and absorption features reveal fluid‐filled fracture networks below regions of magmatic volatile release at the surface and a close spatial association between carbonatite volcanism and deeply penetrating, fluid‐filled faults. High‐absorption features appear sensitive to fluids and thermal gradients, revealing a central sill complex and connected plumbing system down to the mid‐crust, which links volcanoes and rift segments across the developing magmatic rift.
    Description: Plain Language Summary: The interplay between magmatic and tectonic forces during rifting is still debated. While they are a key component of rift development, the complex structures of rifts and melt storage systems scatter and absorb seismic waves passing through them: in turn, this deteriorates the quality of the subsurface images we obtain from them. In this study, we use the loss of energy suffered by seismic waves to image the Natron basin, which hosts extinct volcanoes and the only active natrocarbonatite volcano on Earth, Oldoinyo Lengai. The results identify areas of melt storage and fracture networks that feed volatiles and melt to this volcano. Results suggest that carbonatite melts may ascend through the crust efficiently along deep‐seated faults systems, while silicate melts in the region may be primarily sourced from a separate melt reservoir. This reservoir, which is elongate and oriented oblique to the general trend of the rift, may act as a magmatic transfer zone between two rift segments.
    Description: Key Points: First fine‐scale 3D images reveal an interconnected rift plumbing system using scattering and absorption mapping. High scattering and absorption mark fluid‐filled faults that degas magmatic fluids and act as potential conduits for carbonatite melts. A high absorption melt reservoir feeds eruptions at Oldoinyo Lengai and dike intrusions and acts as a transfer zone between rift segments.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: Terrestrial Magmatic Systems
    Description: https://github.com/LucaDeSiena/MuRAT
    Description: https://doi.org/10.14470/4W7564850022
    Description: http://doi.org/10.6084/m9.figshare.20101232
    Keywords: ddc:551 ; rift plumbing system ; attenuation imaging ; magma‐fault interactions ; Oldoinyo Lengai ; Natron Basin
    Language: English
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    Seamless Integration of the Coastal Ocean in Global Marine Carbon Cycle Modeling (2022)
    Details
    Publication Date: 2023-01-20
    Description: We present the first global ocean‐biogeochemistry model that uses a telescoping high resolution for an improved representation of coastal carbon dynamics: ICON‐Coast. Based on the unstructured triangular grid topology of the model, we globally apply a grid refinement in the land‐ocean transition zone to better resolve the complex circulation of shallow shelves and marginal seas as well as ocean‐shelf exchange. Moreover, we incorporate tidal currents including bottom drag effects, and extend the parameterizations of the model's biogeochemistry component to account explicitly for key shelf‐specific carbon transformation processes. These comprise sediment resuspension, temperature‐dependent remineralization in the water column and sediment, riverine matter fluxes from land including terrestrial organic carbon, and variable sinking speed of aggregated particulate matter. The combination of regional grid refinement and enhanced process representation enables for the first time a seamless incorporation of the global coastal ocean in model‐based Earth system research. In particular, ICON‐Coast encompasses all coastal areas around the globe within a single, consistent ocean‐biogeochemistry model, thus naturally accounting for two‐way coupling of ocean‐shelf feedback mechanisms at the global scale. The high quality of the model results as well as the efficiency in computational cost and storage requirements proves this strategy a pioneering approach for global high‐resolution modeling. We conclude that ICON‐Coast represents a new tool to deepen our mechanistic understanding of the role of the land‐ocean transition zone in the global carbon cycle, and to narrow related uncertainties in global future projections.
    Description: Plain Language Summary: The coastal ocean is an area hardly taken into account by current climate change assessment activities. Yet, its capacity in carbon dioxide (CO2) uptake and storage is crucial to be included in a science‐based development of sustainable climate change mitigation and adaptation strategies. Earth system models are powerful tools to investigate the marine carbon cycle of the open ocean. The coastal ocean, however, is poorly represented in global models to date, because of missing key processes controlling coastal carbon dynamics and too coarse spatial resolutions to adequately simulate coastal circulation features. Here, we introduce the first global ocean‐biogeochemistry model with a dedicated representation of the coastal ocean and associated marine carbon dynamics: ICON‐Coast. In this model, we globally apply a higher resolution in the coastal ocean and extend the accounted physical and biogeochemical processes. This approach enables for the first time a consistent, seamless incorporation of the global coastal ocean in model‐based Earth system research. In particular, ICON‐Coast represents a new tool to deepen our understanding about the role of the land‐ocean transition zone in the global climate system, and to narrow related uncertainties in possible and plausible climate futures.
    Description: Key Points: We introduce the first global ocean‐biogeochemistry model with a dedicated representation of coastal carbon dynamics. We globally apply a grid refinement in the coastal ocean to better resolve regional circulation features, including ocean‐shelf exchange. We explicitly incorporate key physical and biogeochemical processes controlling coastal carbon dynamics.
    Description: German Research Foundation, Excellence Strategy EXC 2037 (CLICCS)
    Description: European Union, Horizon2020 Research and Innovation Program (ESM2025)
    Description: German Federal Ministry of Education
    Description: https://doi.org/10.5281/zenodo.6630352
    Keywords: ddc:551 ; coastal ocean ; global modeling ; marine carbon cycle ; variable‐resolution grid ; ocean‐biogiochemistry ; high‐resolution modeling
    Language: English
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    Locally Resolved Stress‐State in Samples During Experimental Deformation: Insights Into the Effect of Stress on Mineral Reactions (2022)
    Details
    Publication Date: 2023-01-20
    Description: Understanding conditions in the Earth's interior requires data derived from laboratory experiments. Such experiments provide important insights into the conditions under which mineral reactions take place as well as processes that control the localization of deformation in the deep Earth. We performed Griggs‐type general shear experiments in combination with numerical models, based on continuum mechanics, to quantify the effect of evolving sample geometry of the experimental assembly. The investigated system is constituted by CaCO3 and the experimental conditions are near the calcite‐aragonite phase transition. All experimental samples show a heterogeneous distribution of the two CaCO3 polymorphs after deformation. This distribution is interpreted to result from local stress variations. These variations are in agreement with the observed phase‐transition patterns and grain‐size gradients across the experimental sample. The comparison of the mechanical models with the sample provides insights into the distribution of local mechanical parameters during deformation. Our results show that, despite the use of homogeneous sample material (here calcite), stress variations develop due to the experimental geometry. The comparison of experiments and numerical models indicates that aragonite formation is primarily controlled by the spatial distribution of mechanical parameters. Furthermore, we monitor the maximum pressure and σ1 that is experienced in every part of our model domain for a given amount of time. We document that local pressure (mean stress) values are responsible for the transformation. Therefore, if the role of stress as a thermodynamic potential is investigated in similar experiments, an accurate description of the state of stress is required.
    Description: Plain Language Summary: To understand processes in the Earth's interior, we can simulate the extreme conditions via laboratory experiments by compressing and heating millimeter‐sized samples. Such experiments provide important insights into mineral reactions and processes that control deformation in the Earth. We performed rock deformation experiments close to calcite‐aragonite phase (CaCO3) transition. Deforming the sample leads to stress variations due to the experimental geometry. These variations are documented by locally occurring phase transition and variation in the grain‐size. We performed computer simulations of the deforming sample to quantify, for the first time, the effect of sample geometry on the distribution of mechanical variables, such as stress, pressure, or deformation, inside the sample. The new findings document that any mechanical variable cannot be treated as homogeneous within the sample because the variations can be significant. Deforming the sample leads to stress concentrations. By comparing the experimental observations and simulation results, we show that locally high pressure triggers the phase transition to aragonite, the high‐pressure polymorph. This has important consequences for further thermodynamic interpretations of systems under stress, where the role of deformation, pressure, or maximum principal stress on mineral reactions is investigated.
    Description: Key Points: Heterogeneous stress distribution in deformation experiments is investigated by numerical models, locally resolving mechanical variables. Resolving the mechanical variables in experiments suggests a link between local pressure (mean stress) variations and phase transition. Thermodynamic interpretations of deformed samples require a detailed understanding of local mechanical parameters.
    Description: ETH Zürich Foundation http://dx.doi.org/10.13039/501100012652
    Description: https://doi.org/10.5281/zenodo.6974768
    Keywords: ddc:550.78 ; deformation experiments ; numerical modeling ; phase transition ; rock deformation ; localization ; stress variations
    Language: English
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    Hillslope Sediment Supply Limits Alluvial Valley Width (2022)
    Details
    Publication Date: 2023-01-20
    Description: River‐valley morphology preserves information on tectonic and climatic conditions that shape landscapes. Observations suggest that river discharge and valley‐wall lithology are the main controls on valley width. Yet, current models based on these observations fail to explain the full range of cross‐sectional valley shapes in nature, suggesting hitherto unquantified controls on valley width. In particular, current models cannot explain the existence of paired terrace sequences that form under cyclic climate forcing. Paired river terraces are staircases of abandoned floodplains on both valley sides, and hence preserve past valley widths. Their formation requires alternating phases of predominantly river incision and predominantly lateral planation, plus progressive valley narrowing. While cyclic Quaternary climate changes can explain shifts between incision and lateral erosion, the driving mechanism of valley narrowing is unknown. Here, we extract valley geometries from climatically formed, alluvial river‐terrace sequences and show that across our dataset, the total cumulative terrace height (here: total valley height) explains 90%–99% of the variance in valley width at the terrace sites. This finding suggests that valley height, or a parameter that scales linearly with valley height, controls valley width in addition to river discharge and lithology. To explain this valley‐width‐height relationship, we reformulate existing valley‐width models and suggest that, when adjusting to new boundary conditions, alluvial valleys evolve to a width at which sediment removal from valley walls matches lateral sediment supply from hillslope erosion. Such a hillslope‐channel coupling is not captured in current valley‐evolution models. Our model can explain the existence of paired terrace sequences under cyclic climate forcing and relates valley width to measurable field parameters. Therefore, it facilitates the reconstruction of past climatic and tectonic conditions from valley topography.
    Description: Plain Language Summary: Little is known on how valleys widen and what sets their width. Therefore, it remains difficult to model the wealth of valley geometries that occur in nature and to predict how valleys adjust to environmental changes. Paired river terraces are staircases of abandoned valley floors that preserve valley widths of the past. The formation of river‐terrace sequences requires changes between vertical river incision and lateral river erosion of valley walls. Moreover, to preserve terraces on both sides of the river, the valley has to narrow over time. While cyclic climate changes during the Quaternary can explain the alternations between vertical incision and lateral erosion, they cannot explain why those valleys narrow. Here we investigate past valley geometries in paired, climatically formed river terraces. We find a negative linear relationship between valley width and valley height. We propose that this relationship reflects a balance between sediment that is moved from hillslopes into the channel and the capacity of the river to remove this sediment. Higher valley walls contribute more sediment that protects the wall from further widening. By including this hillslope‐erosion term, valley‐formation models can reproduce paired river terraces, and allow us to work toward “reading” climatic conditions from valley geometries.
    Description: Key Points: Valley width in alluvial terraces is inversely proportional to valley height. We suggest sediment supply from river‐independent hillslope erosion limits valley width. The coupling of hillslopes and river channels demands revision of current valley‐evolution models.
    Description: EC H2020 PRIORITY “Excellent science” H2020 Marie Skłodowska‐Curie Actions http://dx.doi.org/10.13039/100010665
    Description: https://doi.org/10.5880/fidgeo.2022.021
    Keywords: ddc:551.3 ; valley width ; river terraces
    Language: English
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    Non‐exchangeable stable hydrogen isotope ratios in clay minerals and soil clay fractions: A method test (2022)
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-01-20
    Description: Stable hydrogen isotope ratios (δ2H values) in structural hydroxyl groups of pedogenic clay minerals are inherited from the surrounding water at the time of their formation. Only non‐exchangeable H preserves the environmental forensic and paleoclimate information (δ2Hn value). To measure δ2Hn values in structural H of clay minerals and soil clay fractions, we adapted a steam equilibration method by accounting for high hygroscopicity. Our δ2Hn values for USGS57 biotite (−95.3 ± SD 0.9‰) and USGS58 muscovite (30.7 ± 1.4‰) differed slightly but significantly from the reported δ2H values (−91.5 ± 2.4‰ and −28.4 ± 1.6‰), because the minerals contained 1.1%–4.4% of exchangeable H. The low SD of replicate measurements (n = 3) confirmed a high precision. The clay separation method including destruction of Fe oxides, carbonates and soil organic matter, and dispersion did not significantly change the δ2Hn values of five different clay minerals. However, we were unable to remove all organic matter from the soil clay fractions resulting in an estimated bias of 1‰ in two samples and 15‰ in the carbon‐richest sample. Our results demonstrate that δ2Hn values of structural H of clay minerals and soil clay fractions can be reliably measured without interference from atmospheric water and the method used to separate the soil clay fraction. Highlights We tested steam equilibration to determine stable isotope ratios of structural H in clay. Gas‐tight capsule sealing in Ar atmosphere was necessary to avoid remoistening. Our steam equilibration method showed a high accuracy and precision. The clay separation method did not change stable isotope ratios of structural H in clay.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:549 ; controlled isotope exchange technique ; deuterium ; montmorillonite ; soil clay separation ; soil organic matter removal ; steam equilibration ; structural H ; USGS57 biotite ; vermiculite ; δ2H
    Language: English
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    Agent‐Based Modeling of Alternative Futures in the British Land Use System (2022)
    Details
    Publication Date: 2023-01-20
    Description: Socio‐economic scenarios such as the Shared Socioeconomic Pathways (SSPs) have been widely used to analyze global change impacts, but representing their diversity is a challenge for the analytical tools applied to them. Taking Great Britain as an example, we represent a set of stakeholder‐elaborated UK‐SSP scenarios, linked to climate change scenarios (Representative Concentration Pathways), in a globally‐embedded agent‐based modeling framework. We find that distinct model components are required to account for divergent behavioral, social and societal conditions in the SSPs, and that these have dramatic impacts on land system outcomes. From strong social networks and environmental sustainability in SSP1 to land consolidation and technological intensification in SSP5, scenario‐specific model designs vary widely from one another and from present‐day conditions. Changes in social and human capitals reflecting social cohesion, equality, health and education can generate impacts larger than those of technological and economic change, and comparable to those of modeled climate change. We develop an open‐access, transferrable model framework and provide UK‐SSP projections to 2080 at 1 km2 resolution, revealing large differences in land management intensities, provision of a range of ecosystem services, and the knowledge and motivations underlying land manager decision‐making. These differences suggest the existence of large but underappreciated areas of scenario space, within which novel options for land system sustainability could occur.
    Description: Key Points: A national‐scale agent‐based model is developed to represent paired climatic and socio‐economic scenarios in the land system. Key scenario characteristics relate to forms of human behavior, interactions and societal preferences. Large differences emerge between scenarios in terms of land management intensities, ecosystem service provision and land sparing.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Natural Environment Research Council http://dx.doi.org/10.13039/501100000270
    Description: Climate Resilience Programme
    Description: Forestry Commission UK Forestry Commission http://dx.doi.org/10.13039/100017497
    Description: UKRI, Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266
    Description: Global Food Security Programme
    Description: DAAD, German Academic Exchange Service London http://dx.doi.org/10.13039/501100001654
    Description: Government of the United Kingdom http://dx.doi.org/10.13039/100013986
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Karlsruhe Institute of Technology http://dx.doi.org/10.13039/100009133
    Description: Leibniz‐Gemeinschaft http://dx.doi.org/10.13039/501100001664
    Description: https://landchange.earth/CRAFTY
    Description: https://doi.org/10.17605/OSF.IO/CY8WE
    Keywords: ddc:333.7 ; land use change ; land use model ; scenario analysis ; socio‐economic scenario ; model evaluation ; TRACE
    Language: English
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    Decadal Prediction of Marine Heatwaves in MPI‐ESM (2022)
    Details
    Publication Date: 2023-01-20
    Description: Marine Heatwaves (MHW) are SST extremes that can have devastating impacts on marine ecosystems and can influence circulation patterns in the ocean and the atmosphere. Here, we present a first attempt to study the decadal predictability of MHW in an ensemble of decadal hindcasts based on the Max Planck Institute Earth System Model. For the global mean we find significant skill for the multiyear MHW trends but we cannot predict the interannual to decadal variability of MHW. In the Subpolar North Atlantic, we can predict the interannual to decadal variability of MHW days and frequency up to lead year 8. We demonstrate that in the Subpolar North Atlantic, any increase in SST is accompanied by more MHW and vice versa. Thereby we gain additional information about the decadal evolution of SST that go beyond predicting the yearly mean SST.
    Description: Plain Language Summary: Marine Heatwaves (MHW) are periods with extremely warm ocean temperatures that can be disruptive for many marine ecosystems. Here, we provide an attempt to predict the evolution of MHW in the global ocean for the following two to ten years. With this analysis we improve our understanding of the predictability of surface temperatures in the global ocean. We find that there are strong regional differences in the predictability of MHW. One region where MHW can be predicted successfully is the Subpolar North Atlantic. We show that an increase in mean ocean temperature also results in an increase in MHW.
    Description: Key Points: Global mean multiyear trends for Marine Heatwaves (MHW) days and frequency can be skillfully predicted for the following two to eight years. In the Subpolar North Atlantic, yearly characteristics MHW days and frequency are predictable up to leadyear eight. Any increase in SST in the Subpolar North Atlantic is accompanied by an increase in MHW and vice versa.
    Description: Copernicus Climate Change Service
    Description: Deutsche Forschungsgemeinschaft
    Description: http://hdl.handle.net/hdl:21.14106/f2fdc61b13828ed5284f4e4ab41e63f8a84c6e52
    Keywords: ddc:551.46 ; Marine Heatwaves ; decadal predictions ; North Atlantic ; extreme events
    Language: English
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    Hydrologic Turnover Matters — Gross Gains and Losses of Six First‐Order Streams Across Contrasting Landscapes and Flow Regimes (2022)
    Details
    Publication Date: 2023-01-20
    Description: Gross gains and losses of stream water and the consequent hydrologic turnover may modify the composition of stream water and drive in‐stream ecological functioning. We evaluated over 500 breakthrough curves of conservative tracer additions to analyze the channel water balance resulting in gross gains and losses, net exchange, and hydrologic turnover. During the hydrological year 2019, seven tracer experiments had been carried out in six first‐order streams along 400 m study reaches. All streams are located in the Holtemme catchment (Central Germany) with three each dominated by forested and agricultural land use. Four of the six streams were characterized by net‐losing conditions. The overall median of gross exchange was five times higher than net exchange. On average, subsurface gains replaced 50% of the original stream water over less than one kilometer of stream length. We even observed cases where over 95% of the stream water turned over within 100 m. Gross exchange was relatively higher in forested than in agricultural streams. Patterns of exchange in the forested streams persisted spatially and were temporally independent of streamflow, whereas in the agricultural ones, variable spatial patterns and streamflow dependence occurred. Overall, moderate flow coincided with highest relative gross exchange. Our results support previous findings that in‐stream solute concentrations could heavily depend on location and magnitude of gains and losses. Gross exchange embodies a permanent but variable control of downstream solute concentrations interacting with the signal of biogeochemical activity. We highlight the importance to include reach‐scale hydrological processes in studies on nutrient spiraling.
    Description: Plain Language Summary: The vitality of stream ecosystems largely relies on the exchange of water between surface and groundwater. This comprises all gains and losses of stream water from and to the subsurface and is referred to as gross exchange. We investigated gross exchange for six headwater streams in the Holtemme catchment (Central Germany) during the hydrological year 2019. By applying salt tracer experiments we calculated the extent of exchange. Consistently, the investigated stream reaches lost more water than they gained. On average, half of the stream water was replaced by newly added groundwater along less than one km of stream length and, in few cases, almost the entire volume was exchanged within 100 m distance. Streams surrounded by forest exchanged more water than streams in agricultural landscapes. The location and direction of exchange remained similar in the forested streams, but varied temporarily for the agricultural streams. We could show that groundwater represents an important volume of our streams and that the true gross exchange can easily be underestimated if only the sum of gains and losses is measured. Therefore, solute concentrations can be strongly modified by gross exchange, which is important to better understand the transport of solutes in streams.
    Description: Key Points: In over 90% of the cases, gross exchange equals five times the net exchange, which impacts interpretations of nutrient uptake. Gross exchange and hydrologic turnover show spatiotemporal patterns persisting over discharge at forested, but not at agricultural sites. Moderate discharge exhibits the highest relative gross exchange.
    Keywords: ddc:551.48 ; gross gain and loss ; hydrologic turnover ; headwater streams ; reach scale ; losing streams ; land use
    Language: English
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    Solar Activity Driven 27‐Day Signatures in Ionospheric Electron and Molecular Oxygen Densities (2022)
    Details
    Publication Date: 2023-01-20
    Description: The complex interactions in the upper atmosphere, which control the height‐dependent ionospheric response to the 27‐day solar rotation period, are investigated with the superposed epoch analysis technique. 27‐day signatures describing solar activity are calculated from a solar proxy (F10.7) and wavelength‐dependent extreme ultraviolet (EUV) fluxes (Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Solar EUV Experiment), and the corresponding 27‐day signatures describing ionospheric conditions are calculated from electron density profiles (Pruhonice ionosonde station) and O2 density profiles (Global‐scale Observations of the Limb and Disk). The lag analysis of these extracted signatures is applied to characterize the delayed ionospheric response at heights from 100 to 300 km and the impact of major absorption processes in the lower (dominated by O2) and upper ionosphere (dominated by O) is discussed. The observed variations of the delay in these regions are in good agreement with model simulations in preceding studies. Additionally, the estimated significance and the correlation of the delays based on both ionospheric parameters are good. Thus, variations such as the strong shift in 27‐day signatures for the O2 density at low heights are also reliably identified (up to half a cycle). The analysis confirms the importance of ionospheric and thermospheric coupling to understand the variability of the delayed ionospheric response and introduces a method that could be applied to additional ionosonde stations in future studies. This would allow to describe the variability of the delayed ionospheric response spatially, vertically and temporally and therefore may contribute further to the understanding of processes and improve ionospheric modeling.
    Description: Key Points: 27‐day signatures are extracted from ionospheric Ne and nO2 via superposed epoch analysis and a lag analysis is applied. The height‐dependent delay of the extracted 27‐day signatures is characterized by major absorption processes of O and O2. Good correlations between observed delays of Ne and nO2 confirm modeling results in preceding studies.
    Keywords: ddc:538.767 ; ionosphere ; thermosphere ; solar EUV ; superposed epoch analysis
    Language: English
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    A Parameterization of Cirrus Cloud Formation: Revisiting Competing Ice Nucleation (2022)
    Details
    Publication Date: 2023-01-20
    Description: This study develops an advanced physically‐based parameterization of heterogeneous ice nucleation in cirrus clouds that includes an updated parameterization of stochastic homogeneous freezing of supercooled solution droplets. Both components are formulated based on the same methodology and level of approximation, without numerical integration of the underlying ice supersaturation equation. The new scheme includes measured ice nucleation spectra describing deterministic ice activation from an arbitrary number of types of ice‐nucleating particles (INPs), tracks the competition for available water vapor between the different ice nucleation modes, and allows for new ice formation and growth within pre‐existing cirrus clouds. The computationally efficient scheme works with a minimal set of physical input parameters and predicts total nucleated ice crystal number concentrations (ICNCs) along with the maximum ice supersaturation attained during cirrus formation events. Aspects of its implementation into host models are discussed, including the provision of suitably parameterized vertical wind speeds. The parameterization is validated by comparisons to numerical simulations. First off‐line applications to mineral dust and aviation soot particles are presented, including ICNC ensemble statistics resulting from the coupling with statistics of updraft speed variability.
    Description: Plain Language Summary: Two decades after introduction of the first parameterization of cirrus cloud formation by freezing of ubiquitous liquid solution droplets, an improved version is developed based on the latest experimental findings regarding solid ice‐nucleating particles, a small subset of the atmospheric aerosol. The new scheme allows to predict ice crystal formation in cirrus from competing homogeneous freezing and heterogeneous ice activation more realistically and with greater computational efficiency. It considers new developments regarding the properties of vertical wind speeds (triggering ice formation) and the molecular kinetics of water vapor uptake onto ice crystals (controlling ice growth). This study explains the foundation of cirrus ice formation and growth based on cloud physical theory, derives and explains the parameterization, discusses its use in host models to facilitate applications, checks its performance by comparison to comprehensive numerical simulations, and presents first results involving mineral dust and aircraft‐emitted soot particles as examples for good and poor atmospheric ice‐nucleating particles, respectively.
    Description: Key Points: Competing ice nucleation processes in cirrus are predicted reliably and efficiently. Partial activation of dust particles may occur frequently in cirrus formation. Nucleation of ice within already‐existing cirrus requires high updraft speeds.
    Keywords: ddc:551.5 ; cirrus ; ice nucleation ; parameterization ; dust
    Language: English
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    An Empirical Model of the Equatorial Electron Pitch Angle Distributions in Earth's Outer Radiation Belt (2022)
    Smirnov, Artem ; Shprits, Yuri Y. ; Allison, Hayley ; [et al.]
    Details
    Publication Date: 2023-01-20
    Description: In this study, we present an empirical model of the equatorial electron pitch angle distributions (PADs) in the outer radiation belt based on the full data set collected by the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard the Van Allen Probes in 2012–2019. The PADs are fitted with a combination of the first, third and fifth sine harmonics. The resulting equation resolves all PAD types found in the outer radiation belt (pancake, flat‐top, butterfly and cap PADs) and can be analytically integrated to derive omnidirectional flux. We introduce a two‐step modeling procedure that for the first time ensures a continuous dependence on L, magnetic local time and activity, parametrized by the solar wind dynamic pressure. We propose two methods to reconstruct equatorial electron flux using the model. The first approach requires two uni‐directional flux observations and is applicable to low‐PA data. The second method can be used to reconstruct the full equatorial PADs from a single uni‐ or omnidirectional measurement at off‐equatorial latitudes. The model can be used for converting the long‐term data sets of electron fluxes to phase space density in terms of adiabatic invariants, for physics‐based modeling in the form of boundary conditions, and for data assimilation purposes.
    Description: Plain Language Summary: Pitch angle distributions (PADs) are critically important for understanding the dynamics of trapped electrons in Earth's radiation belt region. Specific PAD types are linked to processes acting within the radiation belts which relate to the origins and loss mechanisms of the particle populations, as well as wave activity. In this study we present a polynomial model of the equatorial electron PADs at energies 30 keV–1.6 MeV with a continuous dependence on L‐shell, magnetic local time and activity driven by the solar wind dynamic pressure. The model can be used to reconstruct equatorial electron flux from observations at high latitudes and can be applied for converting the long‐term electron flux data sets to phase space density, driving the boundary conditions for the physics‐based simulations and for data assimilation.
    Description: Key Points: A sum of the first, third, and fifth sine harmonics is used to approximate equatorial electron Pitch angle distributions (PADs) measured by the MagEIS detector onboard the Van Allen Probes. We present a PAD model with a continuous dependence on L, magnetic local time and activity, driven by the solar wind dynamic pressure. The model allows reconstructions of equatorial PADs from uni‐ and omni‐directional measurements at off‐equatorial latitudes.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: https://doi.org/10.5880/GFZ.2.7.2022.001
    Keywords: ddc:538.76 ; pitch angle ; radiation belt ; model ; magnetosphere ; van allen probes ; electrons
    Language: English
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    Bergordnung Graf Egino IV. von Freiburg für die Bergwerke auf dem Diesselmut (2023)
    Details
    Publication Date: 2023-01-20
    Description: Die Entstehung dieser als Bergweistum bezeichnete Bergordnung von Graf Egino IV. für die Bergwerke auf dem Diesselmut am 30. Juni 1372 ist auf die unklaren Rechtsverhältnisse beim Silberbergbau im Breisgau zur damaligen Zeit zurückzuführen. In einem Frage- und Antwortspiel mit 10 namentlich genannten Bergverständigen klärte Graf Egino IV. seine Rechtsansprüche am Silberbergbau.
    Description: source
    Keywords: Graf Egino IV. von Freiburg ; Breisgau ; Freiburg im Breisgau ; Kloster St. Trudpert ; Todtnau ; Silberbergbau ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
    Format: 6
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    Gravity field modelling for the Hannover 10 m atom interferometer (2020)
    Schilling, Manuel ; Wodey, Étienne ; Timmen, Ludger ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-03
    Description: Absolute gravimeters are used in geodesy, geophysics and physics for a wide spectrum of applications. Stable gravimetric measurements over timescales from several days to decades are required to provide relevant insight into geophysical processes. Users of absolute gravimeters participate in comparisons with a metrological reference in order to monitor the temporal stability of the instruments and determine the bias to that reference. However, since no measurement standard of higher-order accuracy currently exists, users of absolute gravimeters participate in key comparisons led by the International Committee for Weights and Measures. These comparisons provide the reference values of highest accuracy compared to the calibration against a single gravimeter operated at a metrological institute. The construction of stationary, large-scale atom interferometers paves the way for a new measurement standard in absolute gravimetry used as a reference with a potential stability up to 1 nm/s 2 at 1 s integration time. At the Leibniz University Hannover, we are currently building such a very long baseline atom interferometer with a 10-m-long interaction zone. The knowledge of local gravity and its gradient along and around the baseline is required to establish the instrument’s uncertainty budget and enable transfers of gravimetric measurements to nearby devices for comparison and calibration purposes. We therefore established a control network for relative gravimeters and repeatedly measured its connections during the construction of the atom interferometer. We additionally developed a 3D model of the host building to investigate the self-attraction effect and studied the impact of mass changes due to groundwater hydrology on the gravity field around the reference instrument. The gravitational effect from the building 3D model is in excellent agreement with the latest gravimetric measurement campaign which opens the possibility to transfer gravity values with an uncertainty below the 10 nm/s2 level.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Niedersächsisches Ministerium für Wissenschaft und Kultur http://dx.doi.org/10.13039/501100010570
    Description: https://www.bipm.org/kcdb
    Keywords: ddc:526 ; Atom interferometry ; Gravity acceleration ; Absolute gravimetry ; Gravimeter reference
    Language: English
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    The combined global gravity field model XGM2019e (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-03
    Description: XGM2019e is a combined global gravity field model represented by spheroidal harmonics up to degree and order (d/o) 5399, corresponding to a spatial resolution of 2′ (~ 4 km). As data sources, it includes the satellite model GOCO06s in the longer wavelength range up to d/o 300 combined with a ground gravity grid which also covers the shorter wavelengths. The ground data consist over land and ocean of gravity anomalies provided by courtesy of NGA (15′ resolution, identical to XGM2016) augmented with topographically derived gravity information over land (EARTH2014). Over the oceans, gravity anomalies derived from satellite altimetry are used (DTU13 with a resolution of 1′). The combination of the satellite data with the ground gravity observations is performed by using full normal equations up to d/o 719 (15′). Beyond d/o 719, a block-diagonal least squares solution is calculated for the high-resolution ground gravity data (from topography and altimetry). All calculations are performed in the spheroidal harmonic domain. In the spectral band up to d/o 719, the new model shows a slightly improved behaviour in the magnitude of a few mm RMS over land as compared to preceding models such as XGM2016, EIGEN6c4 or EGM2008 when validated with independent geoid information derived from GNSS/levelling. Over land and in the spectral range above d/o 719, the accuracy of XGM2019e marginally suffers from the sole use of topographic forward modelling, and geoid differences at GNSS/levelling stations are increased in the order of several mm RMS in well-surveyed areas, such as the US and Europe, compared to models containing real gravity data over their entire spectrum, e.g. EIGEN6c4 or EGM2008. However, GNSS/levelling validation also indicates that the performance of XGM2019e can be considered as globally more consistent and independent of existing high-resolution global models. Over the oceans, the model exhibits an enhanced performance (equal or better than preceding models), which is confirmed by comparison of the MDT’s computed from CNES/CLS 2015 mean sea surface and the high-resolution geoid models. The MDT based on XGM2019e shows fewer artefacts, particularly in the coastal regions, and fits globally better to DTU17MDT which is considered as an independent reference MDT.
    Description: European Space Agency http://dx.doi.org/10.13039/501100000844
    Keywords: ddc:526 ; Gravity ; Combined gravity field model ; Spherical harmonics ; Spheroidal harmonics ; Full normal equation systems ; High-performance computing
    Language: English
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    Self-tuning robust adjustment within multivariate regression time series models with vector-autoregressive random errors (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-03
    Description: The iteratively reweighted least-squares approach to self-tuning robust adjustment of parameters in linear regression models with autoregressive (AR) and t-distributed random errors, previously established in Kargoll et al. (in J Geod 92(3):271–297, 2018. https://doi.org/10.1007/s00190-017-1062-6), is extended to multivariate approaches. Multivariate models are used to describe the behavior of multiple observables measured contemporaneously. The proposed approaches allow for the modeling of both auto- and cross-correlations through a vector-autoregressive (VAR) process, where the components of the white-noise input vector are modeled at every time instance either as stochastically independent t-distributed (herein called “stochastic model A”) or as multivariate t-distributed random variables (herein called “stochastic model B”). Both stochastic models are complementary in the sense that the former allows for group-specific degrees of freedom (df) of the t-distributions (thus, sensor-component-specific tail or outlier characteristics) but not for correlations within each white-noise vector, whereas the latter allows for such correlations but not for different dfs. Within the observation equations, nonlinear (differentiable) regression models are generally allowed for. Two different generalized expectation maximization (GEM) algorithms are derived to estimate the regression model parameters jointly with the VAR coefficients, the variance components (in case of stochastic model A) or the cofactor matrix (for stochastic model B), and the df(s). To enable the validation of the fitted VAR model and the selection of the best model order, the multivariate portmanteau test and Akaike’s information criterion are applied. The performance of the algorithms and of the white noise test is evaluated by means of Monte Carlo simulations. Furthermore, the suitability of one of the proposed models and the corresponding GEM algorithm is investigated within a case study involving the multivariate modeling and adjustment of time-series data at four GPS stations in the EUREF Permanent Network (EPN).
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:526 ; Regression time series ; Vector-autoregressive model ; Cross-correlations ; Multivariate scaled t-distribution ; Self-tuning robust estimator ; Generalized expectation maximization algorithm ; Iteratively reweighted least squares ; Multivariate portmanteau test ; Monte Carlo simulation ; GPS time series
    Language: English
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    Extended forward and inverse modeling of radiation pressure accelerations for LEO satellites (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-03
    Description: For low Earth orbit (LEO) satellites, activities such as precise orbit determination, gravity field retrieval, and thermospheric density estimation from accelerometry require modeled accelerations due to radiation pressure. To overcome inconsistencies and better understand the propagation of modeling errors into estimates, we here suggest to extend the standard analytical LEO radiation pressure model with emphasis on removing systematic errors in time-dependent radiation data products for the Sun and the Earth. Our extended unified model of Earth radiation pressure accelerations is based on hourly CERES SYN1deg data of the Earth’s outgoing radiation combined with angular distribution models. We apply this approach to the GRACE (Gravity Recovery and Climate Experiment) data. Validations with 1 year of calibrated accelerometer measurements suggest that the proposed model extension reduces RMS fits between 5 and 27%, depending on how measurements were calibrated. In contrast, we find little changes when implementing, e.g., thermal reradiation or anisotropic reflection at the satellite’s surface. The refined model can be adopted to any satellite, but insufficient knowledge of geometry and in particular surface properties remains a limitation. In an inverse approach, we therefore parametrize various combinations of possible systematic errors to investigate estimability and understand correlations of remaining inconsistencies. Using GRACE-A accelerometry data, we solve for corrections of material coefficients and CERES fluxes separately over ocean and land. These results are encouraging and suggest that certain physical radiation pressure model parameters could indeed be determined from satellite accelerometry data.
    Description: Deutsches Zentrum für Luft- und Raumfahrt http://dx.doi.org/10.13039/501100002946
    Description: ftp://ftp.tugraz.at/outgoing/ITSG/tvgogo/orbits/GRACE/
    Description: ftp://podaac-ftp.jpl.nasa.gov/allData/grace/L1B/JPL/
    Keywords: ddc:526 ; Solar radiation pressure ; Earth radiation pressure ; Satellite force models ; Parameter estimation
    Language: English
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    Using quantum optical sensors for determining the Earth’s gravity field from space (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-03
    Description: Quantum optical technology provides an opportunity to develop new kinds of gravity sensors and to enable novel measurement concepts for gravimetry. Two candidates are considered in this study: the cold atom interferometry (CAI) gradiometer and optical clocks. Both sensors show a high sensitivity and long-term stability. They are assumed on board of a low-orbit satellite like gravity field and steady-state ocean circulation explorer (GOCE) and gravity recovery and climate experiment (GRACE) to determine the Earth’s gravity field. Their individual contributions were assessed through closed-loop simulations which rigorously mapped the sensors’ sensitivities to the gravity field coefficients. Clocks, which can directly obtain the gravity potential (differences) through frequency comparison, show a high sensitivity to the very long-wavelength gravity field. In the GRACE orbit, clocks with an uncertainty level of 1.0 × 10−18 are capable to retrieve temporal gravity signals below degree 12, while 1.0 × 10−17 clocks are useful for detecting the signals of degree 2 only. However, it poses challenges for clocks to achieve such uncertainties in a short time. In space, the CAI gradiometer is expected to have its ultimate sensitivity and a remarkable stability over a long time (measurements are precise down to very low frequencies). The three diagonal gravity gradients can properly be measured by CAI gradiometry with a same noise level of 5.0 mE/√Hz. They can potentially lead to a 2–5 times better solution of the static gravity field than that of GOCE above degree and order 50, where the GOCE solution is mainly dominated by the gradient measurements. In the lower degree part, benefits from CAI gradiometry are still visible, but there, solutions from GRACE-like missions are superior.
    Description: Deutsche Forschungsgemeinschaft
    Description: http://icgem.gfz-potsdam.de/tom_longtime
    Description: https://earth.esa.int/web/guest/-/goce-data-access-7219
    Description: ftp://podaac.jpl.nasa.gov/allData/grace/L1B/JPL/
    Keywords: ddc:526 ; Quantum optical sensors ; Optical clocks ; Relativistic geodesy ; Atomic gradiometry ; Gravity field
    Language: English
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    Observing Earth’s magnetic environment with the GRACE-FO mission (2021)
    Stolle, C. ; Michaelis, I. ; Xiong, C. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission carries magnetometers that are dedicated to enhance the satellite’s navigation. After appropriate calibration and characterisation of artificial magnetic disturbances, these observations are valuable assets to characterise the natural variability of Earth’s magnetic field. We describe the data pre-processing, the calibration, and characterisation strategy against a high-precision magnetic field model applied to the GRACE-FO magnetic data. During times of geomagnetic quiet conditions, the mean residual to the magnetic model is around 1 nT with standard deviations below 10 nT. The mean difference to data of ESA’s Swarm mission, which is dedicated to monitor the Earth’s magnetic field, is mainly within ± 10 nT during conjunctions. The performance of GRACE-FO magnetic data is further discussed on selected scientific examples. During a magnetic storm event in August 2018, GRACE-FO reveals the local time dependence of the magnetospheric ring current signature, which is in good agreement with results from a network of ground magnetic observations. Also, derived field-aligned currents (FACs) are applied to monitor auroral FACs that compare well in amplitude and statistical behaviour for local time, hemisphere, and solar wind conditions to approved earlier findings from other missions including Swarm. On a case event, it is demonstrated that the dual-satellite constellation of GRACE-FO is most suitable to derive the persistence of auroral FACs with scale lengths of 180 km or longer. Due to a relatively larger noise level compared to dedicated magnetic missions, GRACE-FO is especially suitable for high-amplitude event studies. However, GRACE-FO is also sensitive to ionospheric signatures even below the noise level within statistical approaches. The combination with data of dedicated magnetic field missions and other missions carrying non-dedicated magnetometers greatly enhances related scientific perspectives.
    Description: European Space Agency (FR)
    Description: HEIBRIDS
    Description: Projekt DEAL
    Description: ftp://isdcftp.gfz-potsdam.de/grace-fo/MAGNETIC_FIELD
    Keywords: ddc:538.7 ; Earth’s magnetic field ; Geomagnetism ; Ionospheric currents ; Magnetospheric ring current ; Satellite-based magnetometers ; Platform magnetometers ; GRACE-FO
    Language: English
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    Deciphering the Whisper of Volcanoes: Monitoring Velocity Changes at Kamchatka's Klyuchevskoy Group With Fluctuating Noise Fields (2023)
    Details
    Publication Date: 2023-06-21
    Description: Volcanic inflation and deflation often precede eruptions and can lead to seismic velocity changes (dv/v $dv/v$) in the subsurface. Recently, interferometry on the coda of ambient noise‐cross‐correlation functions yielded encouraging results in detecting these changes at active volcanoes. Here, we analyze seismic data recorded at the Klyuchevskoy Volcanic Group in Kamchatka, Russia, between summer of 2015 and summer of 2016 to study signals related to volcanic activity. However, ubiquitous volcanic tremors introduce distortions in the noise wavefield that cause artifacts in the dv/v $dv/v$ estimates masking the impact of physical mechanisms. To avoid such instabilities, we propose a new technique called time‐segmented passive image interferometry. In this technique, we employ a hierarchical clustering algorithm to find periods in which the wavefield can be considered stationary. For these periods, we perform separate noise interferometry studies. To further increase the temporal resolution of our results, we use an AI‐driven approach to find stations with similar dv/v $dv/v$ responses and apply a spatial stack. The impacts of snow load and precipitation dominate the resulting dv/v $dv/v$ time series, as we demonstrate with the help of a simple model. In February 2016, we observe an abrupt velocity drop due to the M7.2 Zhupanov earthquake. Shortly after, we register a gradual velocity increase of about 0.3% at Bezymianny Volcano coinciding with surface deformation observed using remote sensing techniques. We suggest that the inflation of a shallow reservoir related to the beginning of Bezymianny's 2016/2017 eruptive cycle could have caused this local velocity increase and a decorrelation of the correlation function coda.
    Description: Plain Language Summary: Before eruptions, volcanoes inflate due to the rising magma from below. Previous studies have found that these deformations can lead to small changes in the properties of the surrounding rock. We use passive image interferometry, a method that relies on the omnipresent background vibration of the Earth—mostly induced by the oceans, to measure these changes at the Klyuchevskoy Volcanic Group in Kamchatka, Russia. However, in Kamchatka, this background noise is masked and distorted by small earthquakes and tremors originating from the volcanoes themselves. We combine machine learning techniques with established monitoring methods to find times when these tremors remain similar. Afterward, we use data from these time periods in the conventional way to observe changes in the soil and the rock. Our results show that rain‐ and snowfall and the thickness of the snow cover exert the strongest influence on the properties of the rocks. Additionally, we found that a large magnitude 7.2 earthquake, which struck Kamchatka during our study, caused a slight weakening of the rocks due to microstructural damage. We register changes shortly before an eruption and suggest a connection to the beginning of an eruptive cycle in 2016.
    Description: Key Points: Fluctuating noise conditions lead to distortions in noise interferometry studies, which we avoid with the help of machine learning. The seismic velocity on Kamchatka is affected by numerous mechanisms, amongst them environmental, tectonic, and volcanic events. We observe a velocity increase at Bezymianny during February 2016 and link it to the beginning of the eruptive cycle.
    Description: German Research Foundation
    Description: https://doi.org/10.14470/K47560642124
    Description: https://doi.org/10.24381/cds.e2161bac
    Description: https://doi.org/10.5880/GFZ.2.4.2022.002
    Description: https://doi.org/10.5281/zenodo.7481934
    Keywords: ddc:551 ; seismology ; volcano monitoring ; machine learning ; ambient noise ; seismic velocity change ; time varying earth structure
    Language: English
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    The Niederschlag fluorite-(barite) deposit, Erzgebirge/Germany—a fluid inclusion and trace element study (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The Niederschlag fluorite-barite vein deposit in the Western Erzgebirge, Germany, has been actively mined since 2013. We present the results of a first comprehensive study of the mineralogy, petrography, fluid inclusions, and trace element geochemistry of fluorite related to the Niederschlag deposit. Two different stages of fluorite mineralization are recognized. Stage I fluorite is older, fine-grained, associated with quartz, and forms complex breccia and replacement textures. Conversely, the younger Stage II fluorite is accompanied by barite and often occurs as banded and coarse crystalline open-space infill. Fluid inclusion and REY systematics are distinctly different for these two fluorite stages. Fluid inclusions in fluorite I reveal the presence of a low to medium saline (7–20% eq. w (NaCl+CaCl2)) fluid with homogenization temperatures of 140–180 °C, whereas fluorite II inclusions yield distinctly lower (80–120 °C) homogenization temperatures with at least two high salinity fluids involved (18–27% eq. w (NaCl+CaCl2)). In the absence of geochronological data, the genesis of the earlier generation of fluorite-quartz mineralization remains enigmatic but is tentatively related to Permian magmatism in the Erzgebirge. The younger fluorite-barite mineralization, on the other hand, has similarities to many fluorite-barite-Pb-Zn-Cu vein deposits in Europe that are widely accepted to be related to the Mesozoic opening of the northern Atlantic Ocean.
    Description: European Social Fund http://dx.doi.org/10.13039/501100004895
    Keywords: ddc:553.6 ; Fluorite ; Microthermometry ; Fluid inclusions ; Rare earth elements ; Geochemistry ; Metallogenesis ; Industrial minerals
    Language: English
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    The Deep‐Water Plume in the Northwestern Weddell Sea, Antarctica: Mean State, Seasonal Cycle and Interannual Variability Influenced by Climate Modes (2023)
    Details
    Publication Date: 2023-06-21
    Description: We provide an updated estimate of the annual‐mean, seasonal cycle and interannual variability of the transports and properties of the Weddell Sea Bottom Water (WSBW) plume in the northwestern Weddell Sea. For this we used a densely instrumented mooring array deployed across the continental slope between January 2017 and January 2019. We found that the annual‐mean WSBW transport is 3.4 ± 1.5 Sv, corresponding to a cross‐section area of 35 km2 and a maximum thickness of 203 m. The annual mean transport‐weighted properties of WSBW are −0.99°C (Θ), 34.803 g/kg (SA) and 28.44 kg/m3 (γn). The WSBW is characterized by 3 bottom‐intensified velocity cores, which display seasonal variations in flow speed and transport different varieties of WSBW. The seasonal peak of WSBW transport and density is reached in May (4.7 Sv, 28.443 kg m−3) while the minimum values are observed in February (2.8 Sv, 28.435 kg m−3). The coldest WSBW is found between March and May, and the warmest between August and October. The density decrease of WSBW observed in the austral autumn of 2018 can be explained by warmer ambient waters being entrained during the formation of WSBW. This was enabled by the weakening of the along‐shore winds associated with a positive Southern Annular Mode index, reinforced by a La Niña event in early 2018. The synchronous decrease of total WSBW transport and volume between September 2018 and February 2019 indicates a reduction in the export of the dense precursors of WSBW from the Weddell Sea continental shelf.
    Description: Plain Language Summary: The Meridional Overturning Circulation (MOC) redistributes heat and carbon dioxide in the world ocean. Thus, it plays an important role in the regulation of our planet's climate. The Weddell Sea is the main contributor to the deep branch of the MOC in the Southern Hemisphere. Despite the importance of this contribution, uncertainties still remain associated to the plume of dense waters transported along the continental slope of the Weddell Sea. To reduce these uncertainties, we analyzed the most densely instrumented mooring array deployed across the continental slope in the northwestern Weddell Sea. We found that this plume flows faster close to the seafloor and that it presents important seasonal and interannual variability. The Weddell Sea Bottom Water interannual variability is influenced by changes in the along‐shore winds driven by the phase of two important climate modes, the Southern Annular Mode and the El Niño‐Southern Oscillation, but also by changes in the export of the dense precursors of WSBW in its formation areas. Increasing our knowledge on the along‐slope plume variability and properties is important to better understand the causes behind the variability of the MOC observed further downstream.
    Description: Key Points: The Weddell Sea Bottom Water (WSBW) plume presents 3 velocity cores and a clear seasonal cycle, with maximum transports and densities in May and minimum in February. A +SAM, reinforced by a ‐ENSO, favors the warming of WSBW via a wind‐driven warming of the ambient waters entrained during its formation. We observed a marked decrease in WSBW density and transports between September 2018 and February 2019 compared to the previous year.
    Description: EU Horizon 2020 Research and Innovation Program
    Description: German Research Foundation
    Description: Alfred Wegener Institute Helmholtz‐Center
    Description: https://doi.org/10.5281/zenodo.7500163
    Keywords: ddc:551.46 ; Weddell Sea ; WSBW ; Meridional Overturning Circulation ; SAM ; ENSO ; deep‐water plume
    Language: English
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    Testing the success of palaeontological methods in the delimitation of clam shrimp (Crustacea, Branchiopoda) on extant species (2023)
    Hethke, Manja ; Hartmann, Kai ; Alberti, Matthias ; [et al.]
    Details
    Publication Date: 2023-06-21
    Description: Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologies strongly overlap within species with little influence on model performance. Ornamentation is commonly species‐diagnostic; seven ornamentation types are distinguished of which six are species‐specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5061/dryad.fbg79cnxs
    Keywords: ddc:565 ; clam‐shrimp carapace ; morphometrics ; species delimitation ; Spinicaudata ; Ozestheria ; Australia
    Language: English
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    Constraints on the pre-eruptive magmatic history of the Quaternary Laacher See volcano (Germany) (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Ba zonation patterns in sanidine phenocrysts from mafic and intermediate phonolite and crystal-rich cumulates from the Laacher See volcano (12.9 ka) in western Germany document diffusion times suggestive of periodic recharge events throughout the magma reservoir’s entire lifespan of ~ 24 ky. Phenocrysts analysed from samples that formed late at the base of the compositionally zoned magma reservoir by mixing and mingling between a resident phonolite magma and recharging basanite show resorption and thin (2–10 μm) late-stage Ba-rich overgrowth. Short diffusion profiles across these boundaries give diffusion times of ~ 1.5–3 years at most, which are interpreted to be the maximum duration between the most recent recharge by the basanite and eruption. The lack of such late overgrowth in samples from other parts of the phonolite reservoir suggests that effect of this mixing and mingling was limited to the crystal-rich base. Sanidines in the cumulates, by contrast, are generally devoid of zoned crystals. Only rare cumulate crystals with resorbed outer boundaries and very thin overgrowths (a few microns) with very sharp compositional changes imply the remobilization of cumulates only months before eruption. Based on the diffusion timescales and storage temperatures obtained in a previous study, we present a genetic model for the conditions and timing of storage and (re-)activation of the magma system prior to the eruption of Laacher See, which is the largest volcanic event in Central Europe since the last glaciation.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Keywords: ddc:551.9 ; Laacher see ; Diffusion chronometry ; Barium ; BSE images ; Magma storage
    Language: English
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    Paleo‐Hydrogeological Modeling to Understand Present‐Day Groundwater Salinities in a Low‐Lying Coastal Groundwater System (Northwestern Germany) (2023)
    Seibert, Stephan L. ; Greskowiak, Janek ; Bungenstock, Friederike ; [et al.]
    Details
    Publication Date: 2023-06-21
    Description: Groundwater abstraction and drainage are considered to be the main drivers for the salinization of low‐lying coastal groundwater systems, while the role of past boundary conditions is less clear. In this study, 3‐D paleo‐hydrogeological variable‐density groundwater flow and salt transport modeling (“paleo‐modeling”) is applied to reconstruct the evolution of groundwater salinities during the Holocene, that is, the last 9,000 years, in Northwestern Germany. Novel aspects of this study include the consideration of highly resolved time‐variant boundary conditions in a 3‐D paleo‐modeling framework, for example, sea‐level rise, surface elevation and coastline changes, development of drainage networks and groundwater abstraction, as well as the quantification of isolated processes impacting salinization. Results show that salinization was a function of sea‐level rise from 9000 BP until 1300 CE. The creation of the dike line ∼1300 CE set the starting point for increasing anthropogenic control of the hydro(geo)logical system: changes in surface elevation and drainage of low‐lying marshes have become main drivers for salinization after 1600 CE when peat was artificially degenerated. Moreover, changes in the dike line caused by storm floods impacted the salinities. Model results for 2020 CE match well with present‐day salinity observations. Yet, salinization will continue in the future, as the hydro(geo)logical system has not reached an equilibrium. The presented paleo‐modeling framework can be viewed as a blueprint for similar low‐lying coastal groundwater systems, influenced by marine transgression and human development. Thereby, it enables the reconstruction of meaningful present‐day salinity distributions, serving as a vital basis for modeling future groundwater systems in a changing climate.
    Description: Key Points: Salinization of a low‐lying coastal groundwater system during the Holocene, that is, 9000 BP until present‐day, was investigated. Sea‐level rise and the evolution of paleogeography were major controls on groundwater salinization during most of the time. Surface elevation changes due to land cultivation, as well as the development of drainage networks, control salinization since ∼1600 CE.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.5281/zenodo.7633381
    Keywords: ddc:551.49 ; saltwater intrusion ; variable‐density groundwater flow ; salt transport ; sea‐level rise ; parameter estimation ; iMOD‐WQ
    Language: English
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    Quantifizierung lokaler Grundwassereintritte in die Spree und deren Bedeutung für die Verockerungsproblematik in der Laustiz (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Eine unbekannte, schwer zu bestimmende aber zentrale Komponente in der Verockerungs-Problematik der Spree ist der lokale Grundwasserzufluss. Als Teil dieser Studie wurden mithilfe des natürlichen Tracers Radon (222Rn) die lokalen Grundwasserzuflüsse in die Spree und Kleine Spree im Lausitzer Braunkohlerevier bestimmt. Der gesamte Grundwasserzufluss, für das 20 km lange Teilstück der Kleinen Spree und den 34 km langen Abschnitt der Spree, variierte je nach Messkampagne zwischen ~3.000 und ~7.000 m3 d−1 (Kleine Spree) sowie ~20.000 und ~38.000 m3 d−1 (Spree). Entlang der Spreewitzer Rinne, einem vom Tagebauabraum geprägten Aquifer, wurden Flussabschnitte mit besonders hohem, präferenziellem Grundwassereintritt identifiziert (bis zu 70 % des gesamten Zustromes). Für diese Bereiche gelangen große Mengen an gelöstem Eisen aus dem Grundwasser in die Fließgewässer. Basierend auf gemessenen lokalen Eisen- und Sulfatfrachten in beiden Fließgewässern, wurde für das Einzugsgebiet die Menge an zurückgehaltenem Eisen quantifiziert. Für das gesamte untersuchte Einzugsgebiet der Spree liegt die Menge an zurückgehaltenem Eisen durch die Eisenhydroxid-Bildung bei bis zu 120 Tonnen/Tag.
    Description: Universität Bayreuth (3145)
    Description: Mapping and quantifying groundwater inflow to the Spree River (Lusatia) and its role in Fe precipitation and coating of the river bed
    Keywords: ddc:551.49 ; Radon as natural tracer ; Quantification of groundwater inflow ; Retention of iron precipitates on the catchment scale ; Iron precipitation in the Spree river
    Language: German
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    Vorkommen von Vanadium im Grundwasser der Vulkaneifel (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: In Quellwasserproben rund um den Ringseitert-Vulkankomplex südöstlich der Gemeinde Kirchweiler (Westeifel) wurden weit über dem Geringfügigkeitsschwellenwert erhöhte Vanadiumkonzentrationen mit einem Maximalwert von 28 μg/l nachgewiesen. Generell zeigten die im Bereich der Känozoischen Vulkanite entnommenen Wasserproben erheblich höhere Konzentrationen als die im umliegenden Paläozoikum. Lokale Vulkanitproben weisen bis zu vierfach über dem Krustenmittel erhöhte Gesamtgehalte an Vanadium auf. Elutionsuntersuchungen ergaben eine erhöhte Vanadiumfreisetzung. Zur weiteren mikroanalytischen Suche nach der geogenen Quelle für diese Anomalie wurden Dünnschliffe der Gesteinsproben hergestellt und mittels Elektronenmikrosonde analysiert. Die Elementverteilungsbilder zeigten nicht die erwartete Korrelation zwischen den Elementen Fe und V, wohl jedoch eine Korrelation zwischen P und V. Hotspot-Analysen von V‑reichen Mineralkörnern weisen auf das Mineral Fluorapatit mit bis zu 5 Gew.-% Vanadat als Substitution für das Phosphat als geogene Vanadiumquelle in den Vulkaniten hin. Eine hydrogeochemische Modellierung mit PhreePlot zeigt übereinstimmend, dass die Wasserproben mit erhöhten Vanadiumkonzentrationen alle im pe/pH-Prädominanzfeld der Vanadat(V)-Komplexe liegen.
    Description: Johannes Gutenberg-Universität Mainz (1030)
    Keywords: ddc:551.46 ; Volcanic aquifer ; Vanadium mobility ; Vanadate ; V‑bearing Fluorapatite
    Language: German
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    The Schlaining quartz-stibnite deposit, Eastern Alps, Austria: constraints from conventional and infrared microthermometry and isotope and crush-leach analyses of fluid inclusions (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Stibnite was mined until the end of the twentieth century in the Schlaining ore district, Austria, near the easternmost border of the Eastern Alps where windows of Penninic ophiolites and metasediments are exposed below Austroalpine tectonic units. In Early Miocene, structurally controlled small vein and metasomatic stibnite-quartz deposits were formed in Penninic Mesozoic calcareous marbles and calcite schists. Fluid inclusion studies identified two fluids involved in the mineralization: (i) a low-salinity, low-CO2 metamorphic fluid that precipitated quartz at approximately 240 °C and (ii) a stibnite-forming ore fluid that had a meteoric origin. There is no evidence of boiling or that the fluids mixed during mineralization. The ore components Sb and H2S were leached by fluid/rock interaction from buried rock units. Stibnite mineralization occurred by cooling the ore fluid to below 300 °C, at less than 2000 m depth. Quartz precipitated at slightly lower temperatures, approximately contemporaneous with stibnite. Fluid migration and ore deposition are probably related to high heat flow during the exhumation of the Rechnitz Window in response to Neogene extension and/or shallow Early Miocene andesitic magmatism. The study emphasizes that data obtained from the analyses of gangue minerals alone cannot routinely be used to infer the origin and depositional conditions of the associated ore minerals.
    Description: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ (4217)
    Keywords: ddc:553.4 ; Geology ; Mineral Resources ; Mineralogy
    Language: English
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    Horizontal Correlation Functions of Wind Fluctuations in the Mesosphere and Lower Thermosphere (2023)
    Details
    Publication Date: 2023-06-21
    Description: Measurements of kinetic energy in vortical and divergent fluctuations in the mesosphere and lower thermosphere can be used to study stratified turbulence (ST) and gravity waves. This can be done using horizontal correlation functions of the fluctuating component of velocity. This study introduces a novel method for estimating these correlation functions using radars that observe Doppler shifts of ionized specular meteor trails. The technique solves the correlation functions directly on a longitudinal‐transverse‐up coordinate system, assuming axial symmetry. This procedure is more efficient and leads to smaller uncertainties than a previous approach. The new technique is applied to a year‐long data set from a multistatic specular meteor radar network in Germany, to study the annual variability of kinetic energy within turbulent fluctuations at 87–93 km of altitude. In monthly averages, the kinetic energy is found to be nearly equipartitioned between vortical and divergent modes. Turbulent fluctuations maximize during the winter months with approximately 25% more energy in these months than at other times. The horizontal correlation functions are in agreement with the inertial subrange of ST, exhibiting a 2/3 power law in the horizontal lag direction, with an outermost scale of ST to be about 380 km. This suggests that horizontal correlation functions could be used to estimate turbulent energy transfer rates.
    Description: Plain Language Summary: Flows exhibit a phenomenon called turbulence, which transfers energy from large scales into smaller scales. This effect is important to quantify the energy budget of the Earth's upper atmosphere. The range of length scales where this phenomenon occurs is called the inertial subrange of turbulence. The classical theory of isotropic turbulence predicts that this energy transfer occurs on length scales smaller than ∼100 m, at 60–110 km altitude. Recent work has shown that horizontal velocity fluctuations can extend the inertial subrange to length scales of up to hundreds of kilometers horizontally. This type of turbulence is called stratified turbulence (ST). So far no comprehensive study has been made to experimentally examine ST in the mesosphere and lower thermosphere (MLT) region on horizontal mesoscales. This study introduces a method for doing so by measuring how the wind fluctuations are correlated as a function of horizontal separation. This is achieved by using meteor radar measurements. The technique is applied to a year‐long data set over Germany. It is found that the MLT wind fluctuations are compatible with ST theory. The introduced method could potentially be used for routinely measuring how kinetic energy flows from large‐scale to small‐scale atmospheric fluctuations.
    Description: Key Points: A more efficient estimator for horizontal correlation functions is introduced. The rotational and divergent correlation functions of mesosphere and lower thermosphere wind fluctuations are found to be balanced at horizontal mesoscales. Horizontal correlations of wind fluctuations follow a 2/3‐power law for horizontal separations of up to 300–400 km.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: French Ministry of Foreign and European Affairs
    Description: Leibniz SAW project FORMOSA
    Keywords: ddc:551.5 ; mesosphere ; lower thermosphere ; wind fluctuations
    Language: English
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    Envisioning carbon-free land use futures for Sweden: a scenario study on conflicts and synergies between environmental policy goals (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: In climate change mitigation, backcasting scenarios are often used for exploring options for achieving a single environmental goal, albeit at the expense of other goals. This paper assesses potential conflicts and synergies between multiple environmental policy goals based on four future scenarios on Swedish rural land use, assuming zero GHG emissions in 2060. The assessment shows that goal conflicts are apparent, and policy makers need to make trade-offs between goals. The choice of strategy for dealing with these trade-offs yields conflicts or synergies. The assessment shows that a transition to zero GHG emissions provides opportunities for Sweden to shift to carbon free land-use planning. Overall, there are alternative ways with different underlying assumptions to achieve zero GHG emissions, which will feed discussions on new opportunities to overcome multi-scale and multi-sectoral goal conflicts. Multi-target backcasting scenarios are considered more suited to account for the multi-dimensional aspects of goal conflicts. This requires a comprehensive multi-target backcasting approach, which combines the strengths of multicriteria analysis, nexus approaches and backcasting, for supporting a transition to zero GHG emissions.
    Description: Svenska Forskningsrådet Formas http://dx.doi.org/10.13039/501100001862
    Keywords: ddc:304.28 ; Backcasting scenarios ; Goal conflicts ; Synergies ; Climate change mitigation
    Language: English
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    Climate change vulnerability, water resources and social implications in North Africa (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: North Africa is considered a climate change hot spot. Existing studies either focus on the physical aspects of climate change or discuss the social ones. The present article aims to address this divide by assessing and comparing the climate change vulnerability of Algeria, Egypt, Libya, Morocco, and Tunisia and linking it to its social implications. The vulnerability assessment focuses on climate change exposure, water resources, sensitivity, and adaptive capacity. The results suggest that all countries are exposed to strong temperature increases and a high drought risk under climate change. Algeria is most vulnerable to climate change, mainly due to the country’s high sensitivity. Across North Africa, the combination of climate change and strong population growth is very likely to further aggravate the already scarce water situation. The so-called Arab Spring has shown that social unrest is partly caused by unmet basic needs of the population for food and water. Thus, climate change may become an indirect driver of social instability in North Africa. To mitigate the impact of climate change, it is important to reduce economic and livelihood dependence on rain-fed agriculture, strengthen sustainable land use practices, and increase the adaptive capacity. Further, increased regional cooperation and sub-national vulnerability assessments are needed.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: National Geographic Society http://dx.doi.org/10.13039/100006363
    Keywords: ddc:304.28 ; Climate change ; Vulnerability ; Resilience ; Water ; Conflict ; North Africa
    Language: English
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    Sicherung der Lebensgrundlage Grundwasser – eine globale Gemeinschaftsaufgabe (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Grundwasser ist weltweit ein Schlüsselelement der Wasserversorgung, insbesondere der Trinkwasserversorgung. Die Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) ist seit Jahrzehnten in einschlägigen internationalen Projekten engagiert. Im Licht der Herausforderungen des „Global Change“ und basierend auf der jahrzehntelangen Erfahrung bei der Erkundung, Bewertung und Nutzung von Grundwasservorkommen hat die BGR ihre Handlungsschwerpunkte strategisch ausgerichtet. In den kommenden Jahren werden wir uns in Bezug auf das Grundwasser insbesondere mit den Themen Versorgungsicherheit sowie Dynamik und Stoffumsatz von Grundwasserfließsystemen befassen – auch in Verbindung mit den dafür erforderlichen Flächen- und Rauminformationen. In der internationalen Zusammenarbeit stehen beim Thema Versorgungssicherheit die Entwicklung von Erkundungs- und Nutzungsstrategien für aride Gebiete und Küstenzonen sowie die Methodenentwicklung von Prognosewerkzeugen im Vordergrund. Die weltweit dauerhafte Sicherung der Lebensgrundlage Grundwasser kann nur partnerschaftlich gelingen.
    Description: Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) (4230)
    Keywords: ddc:551.49 ; Hydrogeology ; Hydrology/Water Resources ; Water Quality/Water Pollution ; Geoengineering, Foundations, Hydraulics ; Soil Science & Conservation ; Geoecology/Natural Processes
    Language: German
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    Towards more meaningful scenarios of biodiversity responses to land-use change in Central Asia (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: We here respond to Nunez et al. (Reg Environ Chang 20:39, 2020), recently published in Regional Environmental Change. Nunez et al. project biodiversity responses to land-use and climate change in Central Asia. Their projections are based on scenarios of changing socio-economic and environmental conditions for the years 2040, 2070, and 2100. We suggest that the predicted magnitude of biodiversity loss might be biased high, due to four shortfalls in the data used and the methods employed. These are (i) the use of an inadequate measure of “biodiversity intactness,” (ii) a failure to acknowledge for large spatial variation in land-use trends across the five considered Central Asian countries, (iii) the assumption of a strictly linear, negative relationship between livestock grazing intensity and the abundance of animals and plants, and (iv) the extrapolation of grazing-related biodiversity responses into areas of cropland. We conclude that future scenarios of biodiversity response to regional environmental change in Central Asia will benefit from using regional, not global, spatial data on livestock distribution and land-use patterns. The use of extra-regional data on the relationships between biodiversity and land-use or climate should be avoided.
    Description: Westfälische Wilhelms-Universität Münster (1056)
    Keywords: ddc:333.7 ; Livestock ; Grazing ; Steppe ; Fire ; Saiga antelope ; Post-Soviet
    Language: English
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    Global tide simulations with ICON-O: testing the model performance on highly irregular meshes (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The global tide is simulated with the global ocean general circulation model ICON-O using a newly developed tidal module, which computes the full tidal potential. The simulated coastal M2 amplitudes, derived by a discrete Fourier transformation of the output sea level time series, are compared with the according values derived from satellite altimetry (TPXO-8 atlas). The experiments are repeated with four uniform and sixteen irregular triangular grids. The results show that the quality of the coastal tide simulation depends primarily on the coastal resolution and that the ocean interior can be resolved up to twenty times lower without causing considerable reductions in quality. The mesh transition zones between areas of different resolutions are formed by cell bisection and subsequent local spring optimisation tolerating a triangular cell’s maximum angle up to 84°. Numerical problems with these high-grade non-equiangular cells were not encountered. The results emphasise the numerical feasibility and potential efficiency of highly irregular computational meshes used by ICON-O.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.46 ; Ocean modelling ; Tides ; Unstructured grids ; Mesh refinement ; ICON-O
    Language: English
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    Tidal response to sea level rise and bathymetric changes in the German Wadden Sea (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Tidally dominated coasts are directly affected not only by projected rise in mean sea level, but also by changes in tidal dynamics due to sea level rise and bathymetric changes. By use of a hydrodynamic model, which covers the entire German Bight (South-Eastern North Sea), we analyse the effects of sea level rise and potential bathymetric changes in the Wadden Sea on tidal current velocities. The model results indicate that tidal current velocities in the tidal inlets and channels of the Wadden Sea are increased in response to sea level rise. This is explained by the increased ratio of tidal prism to tidal inlet cross-sectional area, which is due to the characteristic hypsometry of tidal basins in the Wadden Sea including wide and shallow tidal flats and relatively narrow tidal channels. The results further indicate that sea level rise decreases ebb dominance and increases flood dominance in tidal channels. This is, amongst others, related to a decreased intertidal area again demonstrating the strong interaction between tidal wave and tidal basin hypsometry in the Wadden Sea. The bathymetry scenario defined in this study includes elevated tidal flats and deepened tidal channels, which is considered a potential future situation under accelerated sea level rise. Application of these bathymetric changes to the model mostly compensates the effects of sea level rise. Furthermore, changes in current velocity due to the altered bathymetry are in the same order of magnitude as changes due to mean sea level rise. This highlights the significance of considering potential bathymetric changes in the Wadden Sea for regional projections of the tidal response to sea level rise.
    Description: Bundesanstalt für Wasserbau (4234)
    Keywords: ddc:551.46 ; Sea level rise ; Tidal basin ; Tidal asymmetry ; Hypsometric control ; Hydrodynamic model ; Wadden Sea
    Language: English
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    Improvements in turbulence model realizability for enhanced stability of ocean forecast and its importance for downstream components (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The numerical stability of ocean circulation models is of high significance in operational forecasting. A substantial improvement in numerical stability of the 3D-ocean model HBM could be achieved by the implementation of new realizability criteria in the turbulence closure scheme. Realizability criteria which were already well documented for closure functions without double diffusion were therefore extended to those using double diffusion. A purely technical validation method called ε-test which is suitable for the detection of numerical stability problems is presented, and the effect of the development in turbulence model is demonstrated under severe weather conditions during extreme storm events. Evaluation of statistics of longer simulations indicate that instabilities appeared only locally and temporary; nevertheless, a significant impact on drift products relying on the current forecasts could be demonstrated, which underlines the importance of realizability in turbulence closure schemes in comprehensive operational model systems including ocean circulation and downstream drift components.
    Description: Bundesamt für Seeschifffahrt und Hydrographie (BSH) (4225)
    Keywords: ddc:551.46 ; turbulence closure ; numerical stability / realizability ; operational forecasting systems
    Language: English
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    Estimates of wind power and radiative near-inertial internal wave flux (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Energy transfer mechanisms between the atmosphere and the deep ocean have been studied for many years. Their importance to the ocean’s energy balance and possible implications on mixing are widely accepted. The slab model by Pollard (Deep-Sea Res Oceanogr Abstr 17(4):795–812, 1970) is a well-established simulation of near-inertial motion and energy inferred through wind-ocean interaction. Such a model is set up with hourly wind forcing from the NCEP-CFSR reanalysis that allows computations up to high latitudes without loss of resonance. Augmenting the one-dimensional model with the horizontal divergence of the near-inertial current field leads to direct estimates of energy transfer spectra of internal wave radiation from the mixed layer base into the ocean interior. Calculations using this hybrid model are carried out for the North Atlantic during the years 1989 and 1996, which are associated with positive and negative North Atlantic Oscillation index, respectively. Results indicate a range of meridional regimes with distinct energy transfer ratios. These are interpreted in terms of the mixed layer depth, the buoyancy frequency at the mixed layer base, and the wind field structure. The average ratio of radiated energy fluxes from the mixed layer to near-inertial wind power for both years is approximately 12%. The dependence on the wind structure is supported by simulations of idealized wind stress fronts with variable width and translation speeds.
    Description: Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659
    Description: Canadian Network for Research and Innovation in Machining Technology, Natural Sciences and Engineering Research Council of Canada https://doi.org/10.13039/501100002790
    Keywords: ddc:551.46 ; Near inertial waves ; Wind ocean coupling ; Internal gravity waves
    Language: English
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    A wind-driven model of the ocean surface layer with wave radiation physics (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Surface windstress transfers energy to the surface mixed layer of the ocean, and this energy partly radiates as internal gravity waves with near-inertial frequencies into the stratified ocean below the mixed layer where it is available for mixing. Numerical and analytical models provide estimates of the energy transfer into the mixed layer and the fraction radiated into the interior, but with large uncertainties, which we aim to reduce in the present study. An analytical slab model of the mixed layer used before in several studies is extended by consistent physics of wave radiation into the interior. Rayleigh damping, controlling the physics of the original slab model, is absent in the extended model and the wave-induced pressure gradient is resolved. The extended model predicts the energy transfer rates, both in physical and wavenumber-frequency space, associated with the wind forcing, dissipation in the mixed layer, and wave radiation at the base as function of a few parameters: mixed layer depth, Coriolis frequency and Brunt-Väisälä frequency below the mixed layer, and parameters of the applied windstress spectrum. The results of the model are satisfactorily validated with a realistic numerical model of the North Atlantic Ocean.
    Description: Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659
    Keywords: ddc:551.5 ; Wind-driven internal gravity waves ; Wave radiation physics
    Language: English
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    Interactions between barotropic tides and mesoscale processes in deep ocean and shelf regions (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The interactions between barotropic tides and mesoscale processes were studied using the results of a numerical model in which tidal forcing was turned on and off. The research area covered part of the East Atlantic Ocean, a steep continental slope, and the European Northwest Shelf. Tides affected the baroclinic fields at much smaller spatial scales than the barotropic tidal scales. Changes in the horizontal patterns of the M2 and M4 tidal constituents provided information about the two-way interactions between barotropic tides and mesoscale processes. The interaction between the atmosphere and ocean measured by the work done by wind was also affected by the barotropic tidal forcing. Tidal forcing intensified the transient processes and resulted in a substantial transformation of the wave number spectra in the transition areas from the deep ocean to the shelf. Tides flattened the sea-surface height spectra down to ~ k−2.5 power law, thus reflecting the large contribution of the processes in the high-frequency range compared to quasi-geostrophic motion. The spectra along sections parallel or normal to the continental slope differ from each other, which indicates that mesoscale turbulence was not isotropic. An analysis of the vorticity spectra showed that the flattening was mostly due to internal tides. Compared with the deep ocean, no substantial scale selectivity was observed on the shelf area. Particle tracking showed that the lengths of the Lagrangian trajectories increased by approximately 40% if the barotropic tidal forcing was activated, which contributed to changed mixing properties. The ratio between the horizontal and vertical scales of motion varied regionally depending on whether barotropic tidal forcing was included. The overall conclusion is that the barotropic tides affect substantially the diapycnal mixing.
    Description: Ministry of Science and Culture of Lower Saxony
    Description: BMBF
    Keywords: ddc:551.46 ; Tides ; Mesoscale processes ; Nonlinear interactions ; Diapycnal mixing ; Spectral energy ; European Northwest Shelf
    Language: English
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    Extending access to localizer performance with vertical guidance approaches by means of an SBAS to GBAS converter (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Currently, many commercial airline aircraft cannot perform three-dimensionally guided approaches based on satellite-based augmentation systems. We propose a system to rebroadcast the correction and integrity data via a data link as provided by the ground-based augmentation system such that aircraft equipped with a GPS landing system (GLS) can use the wide-area corrections and perform localizer performance with vertical guidance (LPV) approaches while maintaining the same level of integrity. In consequence, the system loses some availability and the time to alert is slightly increased. We build a prototype system and present data collected for one week, confirming technical feasibility. There is a loss of 5.3 percent of availability during a 1-week data collection cycle in which we compared our system to standalone LPV service. We tested our prototype with two commercially available GLS receivers with positive results and successfully demonstrated the functionality with a conventional Airbus 319 equipped with a standard GLS receiver.
    Keywords: ddc:526 ; SBAS ; Satellite ; Navigation ; Augmentation ; Aviation ; GPS ; GNSS
    Language: English
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    Two methods to determine scale-independent GPS PCOs and GNSS-based terrestrial scale: comparison and cross-check (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The GPS satellite transmitter antenna phase center offsets (PCOs) can be estimated in a global adjustment by constraining the ground station coordinates to the current International Terrestrial Reference Frame (ITRF). Therefore, the derived PCO values rest on the terrestrial scale parameter of the frame. Consequently, the PCO values transfer this scale to any subsequent GNSS solution. A method to derive scale-independent PCOs without introducing the terrestrial scale of the frame is the prerequisite to derive an independent GNSS scale factor that can contribute to the datum definition of the next ITRF realization. By fixing the Galileo satellite transmitter antenna PCOs to the ground calibrated values from the released metadata, the GPS satellite PCOs in the z-direction (z-PCO) and a GNSS-based terrestrial scale parameter can be determined in GPS + Galileo processing. An alternative method is based on the gravitational constraint on low earth orbiters (LEOs) in the integrated processing of GPS and LEOs. We determine the GPS z-PCO and the GNSS-based scale using both methods by including the current constellation of Galileo and the three LEOs of the Swarm mission. For the first time, direct comparison and crosscheck of the two methods are performed. They provide mean GPS z-PCO corrections of −186 ± 25 mm and −221 ± 37 mm with respect to the IGS values and +1.55 ± 0.22 ppb (parts per billion) and +1.72 ± 0.31 in the terrestrial scale with respect to the IGS14 reference frame. The results of both methods agree with each other with only small differences. Due to the larger number of Galileo observations, the Galileo-PCO-fixed method leads to more precise and stable results. In the joint processing of GPS + Galileo + Swarm in which both methods are applied, the constraint on Galileo dominates the results. We discuss and analyze how fixing either the Galileo transmitter antenna z-PCO or the Swarm receiver antenna z-PCO in the combined GPS + Galileo + Swarm processing propagates to the respective freely estimated z-PCO of Swarm and Galileo.
    Description: Chinese Government Scholarship http://dx.doi.org/10.13039/501100010890
    Description: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ (4217)
    Keywords: ddc:526 ; GNSS ; PCO ; Galileo ; Terrestrial scale ; LEOs
    Language: English
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    Mediterranean wetland conservation in the context of climate and land cover change (2020)
    Leberger, Roxanne ; Geijzendorffer, Ilse R. ; Gaget, Elie ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Wetlands are known to support diverse and unique species assemblages. Globally, but particularly in the Mediterranean basin, they are threatened by climate change and natural habitat loss. Despite an alarming decline of wetlands over the last century, standardised and systematic site assessments at large scale do not exist. Here, we perform an integrated assessment of Mediterranean wetlands by evaluating the combination of wetland protection and anthropogenic pressures, namely climate and land cover change, and the subsequent impact on wintering waterbirds. We used a multivariate partial triadic analysis to quantify climate and land cover change for each site between 1990 and 2005. We found that wetland sites in the southeast of the Mediterranean basin combined low or no protection cover with the highest increases in temperature and losses in natural habitats. Despite these findings, these sites also lack observation data on biodiversity, which may underestimate the resulting impacts. However, there are examples where active conservation measurements contributed positively to slow down wetlands’ reduction. Biodiversity data coverage needs to be ensured, regularly updated, and extended across sites regardless of their protection level, to allow for the assessment of biodiversity trends. This should be further extended to include current investments in remote sensing approaches.
    Description: Horizon 2020 http://dx.doi.org/10.13039/501100007601
    Keywords: ddc:333.7 ; Waterbirds ; Partial triadic analysis ; Biodiversity change ; Indicators ; Protected areas
    Language: English
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    Regional climate downscaling over Europe: perspectives from the EURO-CORDEX community (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP) - Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framework and improving communication with both the General Circulation Model (GCM) and climate data user communities. EURO-CORDEX oversees the design and coordination of ongoing ensembles of regional climate projections of unprecedented size and resolution (0.11° EUR-11 and 0.44° EUR-44 domains). Additionally, the inclusion of empirical-statistical downscaling allows investigation of much larger multi-model ensembles. These complementary approaches provide a foundation for scientific studies within the climate research community and others. The value of the EURO-CORDEX ensemble is shown via numerous peer-reviewed studies and its use in the development of climate services. Evaluations of the EUR-44 and EUR-11 ensembles also show the benefits of higher resolution. However, significant challenges remain. To further advance scientific understanding, two flagship pilot studies (FPS) were initiated. The first investigates local-regional phenomena at convection-permitting scales over central Europe and the Mediterranean in collaboration with the Med-CORDEX community. The second investigates the impacts of land cover changes on European climate across spatial and temporal scales. Over the coming years, the EURO-CORDEX community looks forward to closer collaboration with other communities, new advances, supporting international initiatives such as the IPCC reports, and continuing to provide the basis for research on regional climate impacts and adaptation in Europe.
    Keywords: ddc:551.6 ; EURO-CORDEX ; CORDEX ; Climate change ; Regional climate models ; Regional climate modelling
    Language: English
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    Youngest Cretaceous dinosaur tracksite from the Middle East (Maastrichtian, Farrokhi Formation, Central Iran) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-19
    Description: A late early Maastrichtian dinosaur trampling site is reported from the Farrokhi Formation of the Khur area, Central Iran. The largely indeterminate footprints, some of which may represent undertracks, can be classified as natural moulds (i.e. concave epireliefs) bordered by a raised rim of displaced sediment. They reach diameters of up to 0.5 m and were impressed under very shallow to subaerial conditions in an inter- to supratidal environment. Two generations of traces have been imprinted, initially into a soft, fine-grained carbonate sand and afterwards into a superficially hardened substrate that was still plastic underneath; the change in substrate consistency is supported by a conspicuous cracking pattern around the footprints. As a result, hardly any details of the foot morphology of the trackmakers are recorded. Nevertheless, the occurrence improves our knowledge about dinoturbation and its preservation in different kinds of substrates. Furthermore, it is the youngest record (ca. 70 Ma) of dinosaur locomotion traces from Iran and, in all probability, the entire Middle East.
    Description: Senckenberg Naturhistorische Sammlungen Dresden (3507)
    Keywords: ddc:560 ; Late Cretaceous ; Yazd Block ; Tidal flats ; Dinoturbation ; Emersion ; Composite surface
    Language: English
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    Created by the Monte Peron rock avalanche: Lago di Vedana (Dolomites, Italy) and its sediment record of landscape evolution after a mass wasting event (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-19
    Description: The timing of the Monte Peron Landslide is revised to 2890 cal. BP based on a radiocarbon-dated sediment stratigraphy of Lago di Vedana. This age fosters the importance of hydroclimatic triggers in the light of accelerating global warming with a predicted increase of precipitation enhancing the regional predisposition to large landslides. Moreover, a layer enriched in allochthonous organic and minerogenic detritus dating to the same wet period is interpreted as response to a younger and yet unidentified mass wasting event in the catchment of Lago di Vedana. Rock debris of the Monte Peron Landslide impounded the Cordevole River valley and created a landslide-dammed lake. Around AD 1150, eutrophication of this lacustrine ecosystem started with intensified human occupation – a process that ended 150 years later, when the river was diverted back into its original bed. Most likely, this occurred due to artificial opening of the river dam. In consequence, Lago di Vedana was isolated from an open and minerogenic to an endorheic and carbonaceous lacustrine system. After a monastery was established nearby in AD 1457, a second eutrophication process was initiated due to intensified land use linked with deforestation. Only in the eighteenth and nineteenth centuries, deposition of organic matter decreased coinciding with climatic (Little Ice Age) and cultural changes. Conversational measures are the likely reasons for a trend towards less eutrophic conditions since AD 1950.
    Description: Universität Bremen (1013)
    Description: https://doi.org/10.1594/PANGAEA.937090
    Keywords: ddc:551.3 ; Landslide ; XRF scanning ; Geochemistry ; Soil erosion ; Cultural eutrophication ; Late Holocene
    Language: English
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    Syn-metamorphic sulfidation of the Gamsberg zinc deposit, South Africa (2021)
    Springer Vienna
    Details
    Publication Date: 2023-06-19
    Description: The Mesoproterozoic Aggeneys-Gamsberg ore district, South Africa, is one of the world´s largest sulfidic base metal concentrations and well-known as a prime example of Broken Hill-type base metal deposits, traditionally interpreted as metamorphosed SEDEX deposits. Within this district, the Gamsberg deposit stands out for its huge size and strongly Zn-dominated ore ( 〉14 Mt contained Zn). New electron microprobe analyses and element abundance maps of sulfides and silicates point to fluid-driven sulfidation during retrograde metamorphism. Differences in the chemistry of sulfide inclusions within zoned garnet grains reflect different degrees of interaction of sulfides with high metal/sulfur-ratio with a sulfur-rich metamorphic fluid. Independent evidence of sulfidation during retrograde metamorphism comes from graphic-textured sulfide aggregates that previously have been interpreted as quenched sulfidic melts, replacement of pyrrhotite by pyrite along micro-fractures, and sulfides in phyllic alteration zones. Limited availability of fluid under retrograde conditions caused locally different degrees of segregation of Fe-rich sphalerite into Zn-rich sphalerite and pyrite, and thus considerable heterogeneity in sphalerite chemistry. The invoked sulfur-rich metamorphic fluids would have been able to sulfidize base metal-rich zones in the whole deposit and thus camouflage a potential pre-metamorphic oxidation. These findings support the recently established hypothesis of a pre-Klondikean weathering-induced oxidation event and challenge the traditional explanation of Broken Hill-type deposits as merely metamorphosed SEDEX deposits. Instead, we suggest that the massive sulfide deposits experienced a complex history, starting with initial SEDEX-type mineralization, followed by near-surface oxidation with spatial metal separation, and then sulfidation of this oxidized ore during medium- to high-grade metamorphism.
    Description: Julius-Maximilians-Universität Würzburg (3088)
    Keywords: ddc:553.4 ; Metamorphic sulfidation ; Sulfide inclusions ; Base metal deposit ; Aggeneys ; Gamsberg
    Language: English
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    Fingerprinting Kinetic Isotope Effects and Diagenetic Exchange Reactions Using Fluid Inclusion and Dual‐Clumped Isotope Analysis (2023)
    Details
    Publication Date: 2023-06-19
    Description: Geochemical analyses of carbonate minerals yield multiple parameters which can be used to estimate the temperature and water composition at which they formed. Analysis of fluid trapped in minerals is a potentially powerful tool to reconstruct paleotemperatures as well as diagenetic and hydrothermal processes, as these could represent the parent fluid. Internal fluids play important roles during the alteration of carbonate fossils, lowering energetic barriers associated with resetting of clumped isotopes, as well as mediating the transport of elements during diagenesis. Here, we explore the behavior of the ∆47–∆48 “dual‐clumped” isotope thermometer during fluid‐carbonate interaction and demonstrate that it is highly sensitive to the water/carbonate ratio, behaving as a linear system in “rock buffered” alteration, and as a decoupled system in water‐dominated systems due to non‐linear mixing effects in ∆48. Dry heating experiments show that the extrapolated “heated” end‐member is indistinguishable from the predicted ∆47 and ∆48 value expected for the experimental temperature. Furthermore, we evaluate two common laboratory sampling methods for their ability to thermally alter samples. We find that the temperature of the commonly used crushing cells used to vapourize water for fluid inclusion δ18O analyses is insufficient to cause fluid‐carbonate oxygen isotope exchange, demonstrating its suitability for analyses of fluid inclusions in carbonates. We also find that belemnites sampled with a hand‐drill yield significantly warmer paleotemperatures than those sampled with mortar and pestle. We conclude that thermally‐driven internal fluid‐carbonate exchange occurs indistinguishably from isotopic equilibrium, limited by the extent to which internal water and carbonate can react.
    Description: Plain Language Summary: Carbonate minerals contain multiple, independent, chemical and isotopic parameters which can be used to calculate the temperature at which the mineral formed. If these proxies agree with one another, it has been confidently assumed that the temperature is indeed genuine. Here, we investigate three such parameters and show how they record kinetic processes during mineral formation, as well as thermally‐driven processes which may alter a climate record. We find that this method could potentially be used to study the kinetic factors at play during biomineralization, even if the “true” temperature is unknown. We also find that some thermal processes result in all three parameters agreeing with one another. Because thermal alteration poses a potential dilemma for climate researchers, we investigate two common laboratory preparation techniques that involve heating a sample before analysis: drilling and heating sample for fluid inclusion analysis. We find that the heat of a drill is sufficient to facilitate these reactions, and potentially imparts a warm bias onto paleotemperatures, however the apparatus used for analyzing fluid inclusions does not appear to significantly alter the material. We conclude our approach using fluid inclusion analysis and dual‐clumped isotopes has the potential to resolve many ambiguities in interpreting climate records.
    Description: Key Points: We explore the behavior of dual‐clumped and fluid‐inclusion isotope paleothermometers during thermal alteration. Different conditions during diagenesis may result in discrepant paleotemperature estimates, which may be used to identify altered records. Hand‐drilling belemnites produces sufficient heat to reset paleotemperatures, but the heat during analysis of fluid inclusions does not.
    Description: DFG
    Description: https://doi.org/10.5281/zenodo.7565557
    Keywords: ddc:551.9 ; diagenesis ; clumped isotopes ; fluid inclusions ; numerical modeling
    Language: English
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    Dipolarization Fronts in the Jovian Magnetotail: Statistical Survey of Ion Intensity Variations Using Juno Observations (2023)
    Details
    Publication Date: 2023-06-19
    Description: Energetic particle acceleration and energization in planetary magnetotails are often associated with dipolarization fronts characterized by a rapid increase of the meridional component of the magnetic field. Despite many studies of dipolarization events in Earth's magnetotail, Jupiter’s magnetotail provides an almost ideal environment to study high‐energetic ion acceleration by dipolarization fronts because of its large spatial scales and plasma composition of heavy and light ions. In this study, we focus on the response of different high‐energetic ion intensities (H, He, S, and O) to prominent magnetic dipolarization fronts inside the Jovian magnetotail. We investigate if ion energization and acceleration are present in the observations around the identified dipolarization fronts. Therefore, we present a statistical study of 87 dipolarization front signatures, which are identified in the magnetometer data of the Juno spacecraft from July 2016 to July 2021. For the ion intensity analysis, we use the energetic particle observations from the Jupiter Energetic Particle Detector Instrument. Our statistical study reveals that less than half of the identified events are accompanied by an increase of the ion intensities, while most of the other events show no significant change in the ion intensity dynamics. In about 40% of the events located in the dawn sector a significant decrease of the energy spectral index is detected indicating ion acceleration by the dipolarization fronts.
    Description: Key Points: Eighty‐seven prominent dipolarization front signatures are observed in the MAG data during Juno's prime mission during 21:00–05:30 local time. Less than half of the identified events are accompanied by an increase of the ion intensities. In 40% of the events observed on the dawn side a significant decrease of the energy spectral index indicates ion acceleration by the fronts.
    Description: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.17189/1519711
    Description: https://doi.org/10.17189/1519713
    Keywords: ddc:523 ; Juno ; Jovian magnetotail ; energetic ions ; dipolarization fronts ; JEDI
    Language: English
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    The linkage of 13C and 15N soil depth gradients with C:N and O:C stoichiometry reveals tree species effects on organic matter turnover in soil (2020)
    Springer International Publishing
    Details
    Publication Date: 2023-06-19
    Description: The knowledge of tree species dependent turnover of soil organic matter (SOM) is limited, yet required to understand the carbon sequestration function of forest soil. We combined investigations of 13C and 15N and its relationship to elemental stoichiometry along soil depth gradients in 35-year old monocultural stands of Douglas fir (Pseudotsuga menziesii), black pine (Pinus nigra), European beech (Fagus sylvatica) and red oak (Quercus rubra) growing on a uniform post-mining soil. We investigated the natural abundance of 13C and 15N and the carbon:nitrogen (C:N) and oxygen:carbon (O:C) stoichiometry of litterfall and fine roots as well as SOM in the forest floor and mineral soil. Tree species had a significant effect on SOM δ13C and δ15N reflecting significantly different signatures of litterfall and root inputs. Throughout the soil profile, δ13C and δ15N were significantly related to the C:N and O:C ratio which indicates that isotope enrichment with soil depth is linked to the turnover of organic matter (OM). Significantly higher turnover of OM in soils under deciduous tree species depended to 46% on the quality of litterfall and root inputs (N content, C:N, O:C ratio), and the initial isotopic signatures of litterfall. Hence, SOM composition and turnover also depends on additional—presumably microbial driven—factors. The enrichment of 15N with soil depth was generally linked to 13C. In soils under pine, however, with limited N and C availability, the enrichment of 15N was decoupled from 13C. This suggests that transformation pathways depend on litter quality of tree species.
    Description: Universität Trier (3163)
    Keywords: ddc:550.78 ; Stable isotopes ; Microbial turnover ; Litter ; Roots ; Common garden experiment ; Recultivated forest soil
    Language: English
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    Sea-state contributions to sea-level variability in the European Seas (2020)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-19
    Description: The contribution of sea-state-induced processes to sea-level variability is investigated through ocean-wave coupled simulations. These experiments are performed with a high-resolution configuration of the Geestacht COAstal model SysTem (GCOAST), implemented in the Northeast Atlantic, the North Sea and the Baltic Sea which are considered as connected basins. The GCOAST system accounts for wave-ocean interactions and the ocean circulation relies on the NEMO (Nucleus for European Modelling of the Ocean) ocean model, while ocean-wave simulations are performed using the spectral wave model WAM. The objective is to demonstrate the contribution of wave-induced processes to sea level at different temporal and spatial scales of variability. When comparing the ocean-wave coupled experiment with in situ data, a significant reduction of the errors (up to 40% in the North Sea) is observed, compared with the reference. Spectral analysis shows that the reduction of the errors is mainly due to an improved representation of sea-level variability at temporal scales up to 12 h. Investigating the representation of sea-level extremes in the experiments, significant contributions (〉 20%) due to wave-induced processes are observed both over continental shelf areas and in the Atlantic, associated with different patterns of variability. Sensitivity experiments to the impact of the different wave-induced processes show a major impact of wave-modified surface stress over the shelf areas in the North Sea and in the Baltic Sea. In the Atlantic, the signature of wave-induced processes is driven by the interaction of wave-modified momentum flux and turbulent mixing, and it shows its impact to the occurrence of mesoscale features of the ocean circulation. Wave-induced energy fluxes also have a role (10%) in the modulation of surge at the shelf break.
    Keywords: ddc:551.46 ; Sea state ; Ocean-wave interactions ; Sea level ; Surge
    Language: English
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    Phosphorus and carbon in soil particle size fractions: A synthesis (2020)
    Springer International Publishing
    Details
    Publication Date: 2023-06-19
    Description: Despite the importance of phosphorus (P) as a macronutrient, the factors controlling the pool sizes of organic and inorganic P (OP and IP) in soils are not yet well understood. Therefore, the aim of this study was to gain insights into the pools sizes of OP, IP and organic carbon (OC) in soils and soil particle size fractions. For this purpose, I analyzed the distribution of OP, IP, and OC among particle size fractions depending on geographical location, climate, soil depth, and land use, based on published data. The clay size fraction contained on average 8.8 times more OP than the sand size fraction and 3.9 and 3.2 times more IP and OC, respectively. The OP concentrations of the silt and clay size fraction were both negatively correlated with mean annual temperature (R2 = 0.30 and 0.31, respectively, p 〈 0.001). The OC:OP ratios of the silt and clay size fraction were negatively correlated with latitude (R2 = 0.49 and 0.34, respectively, p 〈 0.001). Yet, the OC:OP ratio of the clay size fraction changed less markedly with latitude than the OC:OP ratio of the silt and the sand size fraction. The OC concentrations of all three particle size fractions were significantly (p 〈 0.05) lower in soils converted to cropland than in adjacent soils under natural vegetation. In contrast, the OP concentration was only significantly (p 〈 0.05) decreased in the sand size fraction but not in the other two particle size fractions due to land-use change. Thus, the findings suggest that OP is more persistent in soil than OC, which is most likely due to strong sorptive stabilization of OP compounds to mineral surfaces.
    Description: German Research Foundation
    Keywords: ddc:631.4 ; Ecological stoichiometry ; Soil nutrients ; Organo-mineral interactions ; Land-use change ; Soil organic matter stabilization ; Persistence ; Soil particle size fractions ; Element ratios ; Organic phosphorus
    Language: English
    Type: doc-type:article
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