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  • 1
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    Anmerkungen zur Schätzung von Schadstofffrachten im Grundwasser (2020)
    Details
    Publication Date: 2023-10-11
    Description: Die Bundes-Bodenschutz- und Altlastenverordnung (BBodSchV) sieht in der Prüfung der Verhältnismäßigkeit von Maßnahmen neben Konzentrationen auch Frachten als Entscheidungskriterium vor. Die Schätzung von Frachten im Sickerwasser am Ort der Beurteilung (Grundwasseroberfläche) wird als schwierig erachtet. Daher erfolgt die Bewertung im Regelfall nur für das Grundwasser. Hierbei wird die Fracht meistens im Abstrom einer kontaminierten Fläche auf der Grundlage von punktuellen Messungen in permanenten oder temporären Grundwassermessstellen abgeschätzt. Diese Schätzungen beruhen regelmäßig auf nur ungenau bekannten oder angenommenen chemischen und physikalischen Parametern. Die Ergebnisse derartiger Schätzungen sind daher zwangsläufig mit großen Unsicherheiten behaftet.
    Description: journal
    Keywords: Grundwasserverunreinigung ; Frachtberechnung
    Language: German
    Type: doc-type:article , publishedVersion
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  • 2
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    Möglichkeiten und Grenzen der Vor-Ort-Analytik (2020)
    Details
    Publication Date: 2023-10-11
    Description: Seit Beginn der Altlastenbearbeitung sind Verfahren der Vor-Ort-Analytik für die Erkundung und Sanierungsbegleitung entwickelt und angewendet worden. Insgesamt ist diese Anwendung aber gering geblieben, insbesondere im Vergleich zum umfangreichen Fachschrifttum zu diesem Thema. In diesem Beitrag wird an Hand von Beispielen diskutiert, woher diese Zurückhaltung der Praktiker rührt und inwieweit sie auf guten Gründen beruht.
    Description: journal
    Keywords: chemische Analytik ; Altlastenuntersuchung
    Language: German
    Type: doc-type:article , publishedVersion
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  • 3
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    Geowissenschaftliche Mitteilungen - GMIT 93 (2023)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2023-10-16
    Description: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2023 enthält die Themenblöcke: GEOfokus: Unterbindung förderinduzierter Salzwasseraufstiege in Trinkwasserbrunnen, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Description: journal
    Keywords: ddc:550 ; GMIT
    Language: German
    Type: doc-type:book , publishedVersion
    Format: 112
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  • 4
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    Flood hazard mapping for data-scarce and ungauged coastal river basins using advanced hydrodynamic models, high temporal-spatial resolution remote sensing precipitation data, and satellite imageries (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-12
    Description: This paper presents an integrated approach to simulate flooding and inundation for small- and medium-sized coastal river basins where measured data are not available or scarce. By coupling the rainfall–runoff model, the one-dimensional and two-dimensional models, and the integration of these with global tide model, satellite precipitation products, and synthetic aperture radar imageries, a comprehensive flood modeling system for Tra Bong river basin selected as a case study was set up and operated. Particularly, in this study, the lumped conceptual model was transformed into the semi-distributed model to increase the parameter sets of donor basins for applying the physical similarity approach. The temporal downscaling technique was applied to disaggregate daily rainfall data using satellite-based precipitation products. To select an appropriate satellite-derived rainfall product, two high temporal-spatial resolution products (0.1 × 0.1 degrees and 1 h) including GSMaP_GNRT6 and CMORPH_CRT were examined at 1-day and 1-h resolutions by comparing with ground-measured rainfall. The CMORPH_CRT product showed better performance in terms of statistical errors such as Correlation Coefficient, Probability of Detection, False Alarm Ratio, and Critical Success Index. Land cover/land use, flood extent, and flood depths derived from Sentinel-1A imageries and a digital elevation model were employed to determine the surface roughness and validate the flood modeling. The results obtained from the modeling system were found to be in good agreement with collected data in terms of NSE (0.3–0.8), RMSE (0.19–0.94), RPE (− 213 to 0.7%), F1 (0.55), and F2 (0.37). Subsequently, various scenarios of flood frequency with 10-, 20-, 50-, and 100-year return periods under the probability analysis of extreme values were developed to create the flood hazard maps for the study area. The flood hazards were then investigated based on the flood intensity classification of depth, duration, and velocity. These hazard maps are significantly important for flood hazard assessments or flood risk assessments. This study demonstrated that applying advanced hydrodynamic models on computing flood inundation and flood hazard analysis in data-scarce and ungauged coastal river basins is completely feasible. This study provides an approach that can be used also for other ungauged river basins to better understand flooding and inundation through flood hazard mapping.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Brandenburgische TU Cottbus-Senftenberg (5408)
    Keywords: ddc:551.48 ; Flood hazard ; Regionalization methods ; Sub-daily rainfall ; MIKE models ; Calibration and validation ; Tra Bong river basin
    Language: English
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  • 5
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    Unpacking future climate extremes and their sectoral implications in western Nepal (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-12
    Description: Existing climate projections and impact assessments in Nepal only consider a limited number of generic climate indices such as means. Few studies have explored climate extremes and their sectoral implications. This study evaluates future scenarios of extreme climate indices from the list of the Expert Team on Sector-specific Climate Indices (ET-SCI) and their sectoral implications in the Karnali Basin in western Nepal. First, future projections of 26 climate indices relevant to six climate-sensitive sectors in Karnali are made for the near (2021–2045), mid (2046–2070), and far (2071–2095) future for low- and high-emission scenarios (RCP4.5 and RCP8.5, respectively) using bias-corrected ensembles of 19 regional climate models from the COordinated Regional Downscaling EXperiment for South Asia (CORDEX-SA). Second, a qualitative analysis based on expert interviews and a literature review on the impact of the projected climate extremes on the climate-sensitive sectors is undertaken. Both the temperature and precipitation patterns are projected to deviate significantly from the historical reference already from the near future with increased occurrences of extreme events. Winter in the highlands is expected to become warmer and dryer. The hot and wet tropical summer in the lowlands will become hotter with longer warm spells and fewer cold days. Low-intensity precipitation events will decline, but the magnitude and frequency of extreme precipitation events will increase. The compounding effects of the increase in extreme temperature and precipitation events will have largely negative implications for the six climate-sensitive sectors considered here.
    Description: Rheinische Friedrich-Wilhelms-Universität Bonn (1040)
    Keywords: ddc:551.6 ; Climate extremes ; ET-SCI ; Climate change impacts ; ClimPACT2 ; Karnali ; Nepal
    Language: English
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  • 6
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    Global patterns of disaster and climate risk—an analysis of the consistency of leading index-based assessments and their results (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-12
    Description: Indices assessing country-level climate and disaster risk at the global scale have experienced a steep rise in popularity both in science and international climate policy. A number of widely cited products have been developed and published over the recent years, argued to contribute critical knowledge for prioritizing action and funding. However, it remains unclear how their results compare, and how consistent their findings are on country-level risk, exposure, vulnerability and lack of coping, as well as adaptive capacity. This paper analyses and compares the design, data, and results of four of the leading global climate and disaster risk indices: The World Risk Index, the INFORM Risk Index, ND-GAIN Index, and the Climate Risk Index. Our analysis clearly shows that there is considerable degree of cross-index variation regarding countries’ risk levels and comparative ranks. At the same time, there is above-average agreement for high-risk countries. In terms of risk sub-components, there is surprisingly little agreement in the results on hazard exposure, while strong inter-index correlations can be observed when ranking countries according to their socio-economic vulnerability and lack of coping as well as adaptive capacity. Vulnerability and capacity hotspots can hence be identified more robustly than risk and exposure hotspots. Our findings speak both to the potential as well as limitations of index-based approaches. They show that a solid understanding of index-based assessment tools, and their conceptual and methodological underpinnings, is necessary to navigate them properly and interpret as well as use their results in triangulation.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:363.7 ; Risk assessment ; Vulnerability assessment ; Indicators ; Climate change adaptation ; Disasters ; Climate policy
    Language: English
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  • 7
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    The Danubian cryptic invader Theodoxus fluviatilis (Gastropoda: Neritidae) in the River Rhine: a potential indicator for metal pollution? (2021)
    Springer US
    Details
    Publication Date: 2023-09-12
    Description: Metal pollution poses a major threat to aquatic systems especially in anthropogenic influenced areas, in as much as metals are persistent in the environment. The freshwater snail Theodoxus fluviatilis has often been used as an indicator species for the ecological status in river monitoring. In the River Rhine, the native Northern-European form of T. fluviatilis is nowadays extinct, whilst the Danubian form is spreading along the river. The aim of our study was to investigate if the cryptic invader is affected by metal exposure present in the River Rhine and to discuss its potential as an indicator for metal pollution. Several environmental abiotic (14 water environmental variables plus five common metal concentrations in water and biofilm) and biotic parameters (biofilm mass) were measured across 23 sites along the River Rhine. Five population and six histopathological parameters were evaluated on snails collected at all 23 sites. Aqueous chromium concentration was positively correlated to the damage of male reproductive organs of T. fluviatilis, and higher ammonium concentration was correlated to a decrease in snail size and an increase in the proportion of juveniles. None of the analysed snail parameters was negatively correlated to concentrations of other metals measured, like copper and zinc. Therefore, based on the parameters evaluated, our results indicate that the Danubian form of T. fluviatilis is only restrictedly suitable as an indicator for metal pollution in the River Rhine system. Further field and laboratory investigations including other stressors are necessary to evaluate the indicator potential of the cryptic invader holistically.
    Keywords: ddc:577.6 ; Chromium ; Histopathological alterations ; Population parameters ; Gonads ; River pollution
    Language: English
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  • 8
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    Soil age and soil organic carbon content shape biochemical responses to multiple freeze–thaw events in soils along a postmining agricultural chronosequence (2021)
    Springer International Publishing
    Details
    Publication Date: 2023-09-12
    Description: Freeze–thaw (FT) events exert a great physiological stress on the soil microbial community and thus significantly impact soil biogeochemical processes. Studies often show ambiguous and contradicting results, because a multitude of environmental factors affect biogeochemical responses to FT. Thus, a better understanding of the factors driving and regulating microbial responses to FT events is required. Soil chronosequences allow more focused comparisons among soils with initially similar start conditions. We therefore exposed four soils with contrasting organic carbon contents and opposing soil age (i.e., years after restoration) from a postmining agricultural chronosequence to three consecutive FT events and evaluated soil biochgeoemical responses after thawing. The major microbial biomass carbon losses occurred after the first FT event, while microbial biomass N decreased more steadily with subsequent FT cycles. This led to an immediate and lasting decoupling of microbial biomass carbon:nitrogen stoichiometry. After the first FT event, basal respiration and the metabolic quotient (i.e., respiration per microbial biomass unit) were above pre-freezing values and thereafter decreased with subsequent FT cycles, demonstrating initially high dissimilatory carbon losses and less and less microbial metabolic activity with each iterative FT cycle. As a consequence, dissolved organic carbon and total dissolved nitrogen increased in soil solution after the first FT event, while a substantial part of the liberated nitrogen was likely lost through gaseous emissions. Overall, high-carbon soils were more vulnerable to microbial biomass losses than low-carbon soils. Surprisingly, soil age explained more variation in soil chemical and microbial responses than soil organic carbon content. Further studies are needed to dissect the factors associated with soil age and its influence on soil biochemical responses to FT events.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Universität zu Köln (1017)
    Description: https://datenzentrum.bonares.de/data-portal.php
    Keywords: ddc:631 ; Agricultural post-mining chronosequence ; Basal respiration ; Biogeochemistry ; Metabolic quotient ; Microbial biomass ; Multiple freeze–thaw
    Language: English
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  • 9
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    Significance of flow rule for the passive earth pressure problem (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-12
    Description: Determination of earth pressures is one of the fundamental tasks in geotechnical engineering. Although many different methods have been utilized to present passive earth pressure coefficients, the influence of non-associated plasticity on the passive earth pressure problem has not been discussed intensively. In this study, finite-element limit analysis and displacement finite-element analysis are applied for frictional materials. Results are compared with selected data from literature in terms of passive earth pressure coefficients, shape of failure mechanism and robustness of the numerical simulation. The results of this study show that passive earth pressure coefficients determined with an associated flow rule are comparable to the Sokolovski solution. However, comparison with a non-associated flow rule reveals that passive earth pressure coefficients are significantly over predicted when following an associated flow rule. Moreover, this study reveals that computational costs for determination of passive earth pressure are considerably larger following a non-associated flow rule. Additionally, the study shows that numerical instabilities arise and failure surfaces become non-unique. It is shown that this problem may be overcome by applying the approach suggested by Davis (Soil Mech 341–354, 1968).
    Description: Ruhr-Universität Bochum (1007)
    Keywords: ddc:550 ; Finite-element limit analysis ; Finite-element analysis ; Non-associated plasticity ; Passive earth pressure
    Language: English
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  • 10
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    Beyond one-way determinism: San Frediano’s miracle and climate change in Central and Northern Italy in late antiquity (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-12
    Description: Integrating palaeoclimatological proxies and historical records, which is necessary to achieve a more complete understanding of climate impacts on past societies, is a challenging task, often leading to unsatisfactory and even contradictory conclusions. This has until recently been the case for Italy, the heart of the Roman Empire, during the transition between Antiquity and the Middle Ages. In this paper, we present new high-resolution speleothem data from the Apuan Alps (Central Italy). The data document a period of very wet conditions in the sixth c. AD, probably related to synoptic atmospheric conditions similar to a negative phase of the North Atlantic Oscillation. For this century, there also exist a significant number of historical records of extreme hydroclimatic events, previously discarded as anecdotal. We show that this varied evidence reflects the increased frequency of floods and extreme rainfall events in Central and Northern Italy at the time. Moreover, we also show that these unusual hydroclimatic conditions overlapped with the increased presence of “water miracles” in Italian hagiographical accounts and social imagination. The miracles, performed by local Church leaders, strengthened the already growing authority of holy bishops and monks in Italian society during the crucial centuries that followed the “Fall of the Roman Empire”. Thus, the combination of natural and historical data allows us to show the degree to which the impact of climate variability on historical societies is determined not by the nature of the climatic phenomena per se, but by the culture and the structure of the society that experienced it.
    Description: Fondazione Cassa di Risparmio di Lucca
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Keywords: ddc:551.6 ; Precipitation ; Roman Empire ; Miracles ; Social feedbacks ; Cultural change
    Language: English
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  • 11
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    The Mie representation for Mercury’s magnetospheric currents (2021)
    Toepfer, S. ; Narita, Y. ; Exner, W. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-12
    Description: Poloidal–toroidal magnetic field decomposition is a useful application of the Mie representation and the decomposition method enables us to determine the current density observationally and unambiguously in the local region of magnetic field measurement. The application and the limits of the decomposition method are tested against the Mercury magnetic field simulation in view of BepiColombo’s arrival at Mercury in 2025. The simulated magnetic field data are evaluated along the planned Mercury Planetary Orbiter (MPO) trajectories and the current system that is crossed by the spacecraft is extracted from the magnetic field measurements. Afterwards, the resulting currents are classified in terms of the established current system in the vicinity of Mercury. Graphical Abstract
    Description: österreichische forschungsförderungsgesellschaft http://dx.doi.org/10.13039/501100004955
    Description: deutsches ministerium für wirtschaft und energie
    Description: deutsche forschungs gesellschaft
    Description: Technische Universität Braunschweig (1042)
    Keywords: ddc:523 ; Poloidal–toroidal decomposition ; Magnetospheric current systems ; Capon’s method
    Language: English
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  • 12
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    Energy‐dispersive X‐ray stress analysis under geometric constraints: exploiting the material's inherent anisotropy (2023)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-09-12
    Description: Two data evaluation concepts for X‐ray stress analysis based on energy‐dispersive diffraction on polycrystalline materials with cubic crystal structure, almost random crystallographic texture and strong single‐crystal elastic anisotropy are subjected to comparative assessment. The aim is the study of the residual stress state in hard‐to‐reach measurement points, for which the sin2ψ method is not applicable due to beam shadowing at larger sample tilting. This makes the approaches attractive for stress analysis in engineering parts with complex shapes, for example. Both approaches are based on the assumption of a biaxial stress state within the irradiated sample volume. They exploit in different ways the elastic anisotropy of individual crystallites acting at the microscopic scale and the anisotropy imposed on the material by the near‐surface stress state at the macroscopic scale. They therefore complement each other, in terms of both their preconditions and their results. The first approach is based on the evaluation of strain differences, which makes it less sensitive to variations in the strain‐free lattice parameter a0. Since it assumes a homogeneous stress state within the irradiated sample volume, it provides an average value of the in‐plane stresses. The second approach exploits the sensitivity of the lattice strain to changes in a0. Consequently, it assumes a homogeneous chemical composition but provides a stress profile within the information depth. Experimental examples from different fields in materials science, namely shot peening of austenitic steel and in situ stress analysis during welding, are presented to demonstrate the suitability of the proposed methods.
    Description: The single‐crystal elastic anisotropy and the anisotropy of the near‐surface (residual) stress state of polycrystalline materials with random texture are exploited in energy‐dispersive X‐ray stress analysis to study samples under constrained measurement conditions.
    Keywords: ddc:548 ; X‐ray stress analysis ; energy‐dispersive diffraction ; polycrystalline materials ; single‐crystal elastic anisotropy
    Language: English
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  • 13
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    Decompression and Fracturing Caused by Magmatically Induced Thermal Stresses (2023)
    Details
    Publication Date: 2023-09-12
    Description: Studies of host rock deformation around magmatic intrusions usually focus on the development of stresses directly related to the intrusion process. This is done either by considering an inflating region that represents the intruding body, or by considering multiphase deformation. Thermal processes, especially volume changes caused by thermal expansion are typically ignored. We show that thermal stresses around upper crustal magma bodies are likely to be significant and sufficient to create an extensive fracture network around the magma body by brittle yielding. At the same time, cooling induces decompression within the intrusion, which can promote the appearance of a volatile phase. Volatile phases and the development of a fracture network around the inclusion may thus be the processes that control magmatic‐hydrothermal alteration around intrusions. This suggests that thermal stresses likely play an important role in the development of magmatic systems. To quantify the magnitude of thermal stresses around cooling intrusions, we present a fully compressible 2D visco‐elasto‐plastic thermo‐mechanical numerical model. We utilize a finite difference staggered grid discretization and a graphics processing unit based pseudo‐transient solver. First, we present purely thermo‐elastic solutions, then we include the effects of viscous relaxation and plastic yielding. The dominant deformation mechanism in our models is determined in a self‐consistent manner, by taking into account stress, pressure, and temperature conditions. Using experimentally determined flow laws, the resulting thermal stresses can be comparable to or even exceed the confining pressure. This suggests that thermal stresses alone could result in the development of a fracture network around magmatic bodies.
    Description: Plain Language Summary: Quantifying the stresses that magma bodies exert on the surrounding rocks is an important part of understanding mechanical processes that control the evolution of magmatic systems and volcanic eruptions. Previous analytical or numerical models typically describe the mechanical response to changes in magma volume due to intrusion or extraction of magma. However, volume changes related to thermal expansion/contraction around a cooling magma body are often neglected. Here, we develop a new software which runs on modern graphics processing unit machines, to quantity the effect of this process. The results show that stresses due to thermal expansion/contraction are significant, and often large enough to fracture the rocks nearby the magma body. Such fracture networks may form permeable pathways for the magma or for fluids such as water and CO〈sub〉2〈/sub〉, thus influencing the evolution of magmatic and hydrothermal systems. Finally we show that cooling and shrinking of magma bodies causes significant decompression which can influence the chemical evolution of the magma during crystallization and devolatilization.
    Description: Key Points: We present a numerical quantification of the effect of thermal stresses in visco‐elasto‐plastic rock with tensile and dilatant shear failure. The pressure drop in thermally contracting upper crustal magma bodies can exceed 100 MPa, potentially triggering devolatilization. Thermal cracking can create an extensive fracture network around an upper crustal magma body.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: https://zenodo.org/record/6958273
    Description: https://doi.org/10.5281/zenodo.6958273
    Keywords: ddc:551.8 ; magmatic intrusions ; host rock deformation ; thermal stress ; numerical quantification
    Language: English
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  • 14
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    Triple‐Element Stable Isotope Analysis of Chloromethane Emitted by Royal Fern and Degraded by Club Moss (2023)
    Details
    Publication Date: 2023-09-12
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Chloromethane (CH〈sub〉3〈/sub〉Cl) is the most abundant natural chlorinated organic compound in the atmosphere playing an important role in catalyzing stratospheric ozone loss. Vegetation emits the largest amounts of CH〈sub〉3〈/sub〉Cl to the atmosphere but its source strength is highly uncertain leading also to large uncertainties in the global budget of CH〈sub〉3〈/sub〉Cl. Triple‐element stable isotope analysis may help to reduce uncertainties because it provides additional process‐level information compared to conventional quantification methods. In this study we performed experiments to obtain a first triple‐elemental isotopic fingerprint (〈sup〉2〈/sup〉H, 〈sup〉13〈/sup〉C, 〈sup〉37〈/sup〉Cl) of CH〈sub〉3〈/sub〉Cl emitted by a relevant plant species (royal fern, 〈italic〉Osmunda regalis〈/italic〉). Isotopic values of all three elements showed considerable differences compared to isotopic values of industrially manufactured CH〈sub〉3〈/sub〉Cl which bodes well for future applications to distinguish individual sources. Isotopic analysis of potential precursors (rain, methoxy groups) of CH〈sub〉3〈/sub〉Cl in plants revealed no measurable change of hydrogen and chlorine isotopic ratios during formation which may provide a simpler route to estimate the isotopic composition of CH〈sub〉3〈/sub〉Cl emissions. Plant degradation experiments of CH〈sub〉3〈/sub〉Cl were carried out with club moss (〈italic〉Selaginella kraussiana〈/italic〉) revealing significant isotopic fractionation for all three elements. The fractionation pattern characterized by epsilon and lambda is inconsistent with known biotic dechlorination reactions indicating a yet unreported biotic degradation mechanism for CH〈sub〉3〈/sub〉Cl. Overall, this study provides first insights into the triple‐elemental isotopic fingerprint of plant emissions and degradation. The results may represent important input data for future isotope‐based models to improve global budget estimates of CH〈sub〉3〈/sub〉Cl and to explore the yet unknown degradation pathways.〈/p〉
    Description: Plain Language Summary: Chloromethane is the most abundant chlorinated organic compound in the atmosphere. It contributes to the destruction of the ozone layer that protects us from skin cancer and genetic damage. Currently, we do not have a good understanding of the sources and removal processes of chloromethane in the atmosphere. In this paper, we use a technique that takes advantage of the different varieties of a chemical element. These so‐called isotopes behave differently during chemical reactions that lead to individual isotopic fingerprints depending on the source or removal process. We used isotopic fingerprints of all three chemical elements in chloromethane and showed that chloromethane produced by a plant (royal fern) differs substantially from chloromethane manufactured by industry. Other plant species such as club moss are able to remove chloromethane from the atmosphere but it is often not clear how this occurs. Isotopic analysis revealed that the studied club moss uses a unique, thus far unknown, way to break down chloromethane. This study demonstrates how information extracted from isotopic fingerprints will help to improve our understanding of sources and removal processes of chloromethane in the atmosphere. It can help to better predict how ozone destruction in the stratosphere affects us in the future.〈/p〉
    Description: Key Points: First triple‐element isotopic characterization of plant CH〈sub〉3〈/sub〉Cl emission and degradation. Plant degradation experiments suggest another yet unknown transformation pathway. Important input data for future isotope based models to improve understanding of global CH〈sub〉3〈/sub〉Cl budget.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.48758/ufz.13388
    Keywords: ddc:551.9 ; CH3Cl ; ozone depletion ; isotopes ; plant emissions ; halogens
    Language: English
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  • 15
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    The Toba supervolcano eruption caused severe tropical stratospheric ozone depletion (2021)
    Nature Publishing Group UK
    Details
    Publication Date: 2023-09-12
    Description: Supervolcano eruptions have occurred throughout Earth’s history and have major environmental impacts. These impacts are mostly associated with the attenuation of visible sunlight by stratospheric sulfate aerosols, which causes cooling and deceleration of the water cycle. Supereruptions have been assumed to cause so-called volcanic winters that act as primary evolutionary factors through ecosystem disruption and famine, however, winter conditions alone may not be sufficient to cause such disruption. Here we use Earth system model simulations to show that stratospheric sulfur emissions from the Toba supereruption 74,000 years ago caused severe stratospheric ozone loss through a radiation attenuation mechanism that only moderately depends on the emission magnitude. The Toba plume strongly inhibited oxygen photolysis, suppressing ozone formation in the tropics, where exceptionally depleted ozone conditions persisted for over a year. This effect, when combined with volcanic winter in the extra-tropics, can account for the impacts of supereruptions on ecosystems and humanity.
    Description: Stratospheric sulfur emissions from the Toba supereruption about 74,000 years ago suppressed ozone formation which caused severe tropical ozone layer depletion and enhanced solar ultraviolet radiation stress, according to Earth system model simulations.
    Description: King Abdullah University of Science and Technology (KAUST) https://doi.org/10.13039/501100004052
    Description: http://hdl.handle.net/10754/667404
    Description: https://github.com/SeregaOsipov/NASA-GISS-ModelE/releases/tag/toba_o3
    Description: https://simplex.giss.nasa.gov/snapshots/
    Keywords: ddc:551 ; Atmospheric chemistry ; Natural hazards ; Palaeoclimate ; Volcanology
    Language: English
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  • 16
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    Volcano‐Tectonic Evolution of the Christiana‐Santorini‐Kolumbo Rift Zone (2022)
    Details
    Publication Date: 2023-09-12
    Description: Located on the Hellenic Arc, the Christiana‐Santorini‐Kolumbo (CSK) rift zone represents one of the most active and hazardous volcano‐tectonic systems in the Mediterranean. Although this rift zone has been intensively studied, its tectonic evolution and the interplay of volcanism and tectonism are still poorly understood. In this study, we use high‐resolution reflection seismic imagery to reconstruct the opening of the rift basins. For the first time, we relate the activity of individual faults with the activity of specific volcanic centers in space and time. Our analysis shows a pre‐volcanic NNE‐SSW‐oriented paleo basin underneath the CSK volcanoes, representing a transfer zone between Pliocene ESE‐WNW‐oriented basins, which was overprinted by a NE‐SW‐oriented tectonic regime hosting Late Pliocene volcanism that initiated at the Christiana Volcano. All subsequent volcanoes evolved parallel to this trend. Two major Pleistocene tectonic pulses preceded fundamental changes in the volcanism of the CSK rift including the occurrence of widespread small‐scale volcanic centers followed by focusing of activity at Santorini with increasing explosivity. The observed correlation between changes in the tectonic system and the magmatism of the CSK volcanoes suggests a deep‐seated tectonic control of the volcanic plumbing system. In turn, our analysis reveals the absence of large‐scale faults in basin segments affected by volcanism indicating a secondary feedback mechanism on the tectonic system. A comparison with the evolution of the neighboring Kos‐Nisyros‐Yali volcanic field zone and Rhodos highlights concurrent regional volcano‐tectonic changes, suggesting a potential arc‐wide scale of the observed volcano‐tectonic interplay.
    Description: Plain Language Summary: How do regional tectonic movements and large volcanoes interact? Seismological studies indicate complex volcano‐tectonic feedback links, but, so far, information on the long‐term interactions between tectonics and volcanism is rarely available. The Christiana‐Santorini‐Kolumbo (CSK) rift zone lies in the Aegean Sea and is notorious for its devastating volcanic eruptions, earthquakes, and tsunamis. This region offers the opportunity to study volcano‐tectonic interactions over several million years. In this study, we use high‐resolution seismic imagery to reconstruct the evolution of the rift basins and the CSK volcanoes. We find that all volcanoes lie in a Pliocene transfer zone connecting extensional basins. Volcanism initiated as this older tectonic regime was intersected by a NE‐SW‐directed fault system. Subsequently, all volcanoes evolved parallel to this trend. Several distinct tectonic reorganizations occurred in the Pleistocene, which had a pronounced influence on the CSK volcanoes. In turn, our analysis indicates that the emergence of volcanism also impacted the tectonic evolution of the rift system hindering the evolution of large‐scale normal faults in the volcanic basins. The observed tectonic reorganizations seem to reflect major changes in the stress regime of the Hellenic Arc, potentially also affecting adjacent volcanic centers whose volcano‐tectonic evolution is only poorly constrained so far.
    Description: Key Points: We reconstruct the volcano‐tectonic evolution of the Christiana‐Santorini‐Kolumbo rift zone using multichannel seismic data. The overprint of a Pleistocene NE‐SW striking fault system on a Pliocene E‐W oriented system initiated the emergence of volcanism. Regional tectonics had a primary control on the volcanic plumbing system, while magmatism had a secondary influence on the tectonic system.
    Description: German Research Foundation DFG
    Description: https://doi.org/10.26022/IEDA/331028
    Keywords: ddc:551.8 ; volcano‐tectonics ; Santorini ; rifting ; back‐arc ; Hellenic Arc ; Aegean Sea
    Language: English
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  • 17
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    The role of clay content and mineral surface area for soil organic carbon storage in an arable toposequence (2021)
    Springer International Publishing
    Details
    Publication Date: 2023-09-13
    Description: Correlations between organic carbon (OC) and fine mineral particles corroborate the important role of the abundance of soil minerals with reactive surfaces to bind and increase the persistence of organic matter (OM). The storage of OM broadly consists of particulate and mineral-associated forms. Correlative studies on the impact of fine mineral soil particles on OM storage mostly combined data from differing sites potentially confounded by other environmental factors. Here, we analyzed OM storage in a soil clay content gradient of 5–37% with similar farm management and mineral composition. Throughout the clay gradient, soils contained 14 mg OC g−1 on average in the bulk soil without showing any systematic increase. Density fractionation revealed that a greater proportion of OC was stored as occluded particulate OM in the high clay soils (18–37% clay). In low clay soils (5–18% clay), the fine mineral-associated fractions had up to two times higher OC contents than high clay soils. Specific surface area measurements revealed that more mineral-associated OM was related to higher OC loading. This suggests that there is a potentially thicker accrual of more OM at the same mineral surface area within fine fractions of the low clay soils. With increasing clay content, OM storage forms contained more particulate OC and mineral-associated OC with a lower surface loading. This implies that fine mineral-associated OC storage in the studied agricultural soils was driven by thicker accrual of OM and decoupled from clay content limitations.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Technische Universität München (1025)
    Description: https://doi.org/10.14459/2018mp1462414
    Keywords: ddc:549 ; Soil organic matter ; Fine mineral particles ; Organic carbon storage ; Clay content ; Organic carbon loading ; Nanoscale secondary ion mass spectrometry
    Language: English
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  • 18
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    Reconstructing the slip velocities of the 1202 and 1759 CE earthquakes based on faulted archaeological structures at Tell Ateret, Dead Sea Fault (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-13
    Description: Archaeological structures built across active faults and ruptured by earthquakes have been used as markers to measure the amount of displacement caused by ground motion and thus to estimate the magnitude of ancient earthquakes. The example used in this study is the Crusader fortress at Tel Ateret (Vadum Iacob) in the Jordan Gorge, north of the Sea of Galilee, a site which has been ruptured repeatedly since the Iron Age. We use detailed laser scans and discrete element models of the fortification walls to deduce the slip velocity during the earthquake. Further, we test whether the in-situ observed deformation pattern of the walls allows quantification of the amount both sides of the fault moved and whether post-seismic creep contributed to total displacement. The dynamic simulation of the reaction of the fortification wall to a variety of earthquake scenarios supports the hypothesis that the wall was ruptured by two earthquakes in 1202 and 1759 CE. For the first time, we can estimate the slip velocity during the earthquakes to 3 and 1 m/s for the two events, attribute the main motion to the Arabian plate with a mostly locked Sinai plate, and exclude significant creep contribution to the observed displacements of 1.25 and 0.5 m, respectively. Considering a minimum long-term slip rate at the site of 2.6 mm/year, there is a deficit of at least 1.6 m slip corresponding to a potential future magnitude 7.5 earthquake; if we assume ~5 mm/year geodetic rate, the deficit is even larger.
    Description: Universität zu Köln (1017)
    Keywords: ddc:551.22 ; Archaeoseismology ; Back calculation of ground motion ; Fault slip-velocity ; Tell Ateret ; Dead sea Fault
    Language: English
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  • 19
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    Pure cross-anisotropy for geotechnical elastic potentials (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-13
    Description: The pure cross-anisotropy is understood as a special scaling of strain (or stress). The scaled tensor is used as an argument in the elastic stiffness (or compliance). Such anisotropy can be overlaid on the top of any elastic stiffness, in particular on one obtained from an elastic potential with its own stress-induced anisotropy. This superposition does not violate the Second Law. The method can be also applied to other functions like plastic potentials or yield surfaces, wherever some cross-anisotropy is desired. The pure cross-anisotropy is described by the sedimentation vector and at most two constants. Scaling with more than two purely anisotropic constants is shown impossible. The formulation was compared with experiments and alternative approaches. Static and dynamic calibration of the pure anisotropy is also discussed. Graphic representation of stiffness with the popular response envelopes requires some enhancement for anisotropy. Several examples are presented. All derivations and examples were accomplished using the algebra program Mathematica.
    Description: Karlsruher Institut für Technologie (KIT) (4220)
    Keywords: ddc:550 ; Cross-anisotropy ; Hyperelasticity ; Inherent anisotropy ; Response envelopes ; Scaling of strain ; Transverse isotropy
    Language: English
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  • 20
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    Ancylotherium pentelicum (Mammalia, Chalicotheriidae) from the late Miocene of Kerassia (Greece) and remarks on its intraspecific variability (2021)
    Kampouridis, Panagiotis ; Roussiakis, Socrates J. ; Giaourtsakis, Ioannis X. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-13
    Description: The first detailed description of Ancylotherium pentelicum (Gaudry and Lartet, 1856) from the late Miocene (Turolian) of Kerassia (Greece) is provided based on three metapodial elements. Potential intraspecific variability of this species in the Eastern Mediterranean has been previously discussed, but no decisive conclusions could be drawn. The present comparison of metapodial elements of A. pentelicum from Kerassia, Pikermi, Samos (Greece), Pinaryaka, Salihpaşalar (Turkey), Kiro Kuchuk (North Macedonia), and Hadjidimovo (Bulgaria) provides evidence for the existence of notable intraspecific variation in both the morphology and especially the size of the species. The morphological differences in the shape and occurrence of some metapodial articular facets are probably associated with the anticipated individual variability and not with sexual dimorphism. On the other hand, the notable metrical variability observed among metapodials of A. pentelicum may be indicative of sexual dimorphism, as has been previously documented in other chalicotheriids.
    Description: Research Account of the National and Kapodistrian University of Athens
    Keywords: ddc:569 ; Chalicotheres ; Intraspecific variability ; Postcranial ; Turolian ; Eastern Mediterranean
    Language: English
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  • 21
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    Facies, magnetic susceptibility and timing of the Late Devonian Frasnian/Famennian boundary interval (Xom Nha Formation, Central Vietnam) (2021)
    Ta, Hoa Phuong ; Königshof, Peter ; Ellwood, Brooks B. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-13
    Description: Upper Devonian carbonates deposited through the Frasnian/Famennian (F/F) stage boundary in the Xom Nha Formation, Central Vietnam, were studied. The section is mainly composed of fossiliferous, brecciated, and laminated limestone beds, while shale beds occur in a subordinate number. Microfacies generally suggests a hemipelagic setting on an outer shelf environment with low sedimentation rates. A sediment accumulation rate of 0.217 cm/kyrs for this section is calculated. The Xom Nha section does not exhibit characteristic black shales or black limestones through the F/F boundary, but instead shows a similar lithology in comparison to other F/F sections in Southeast Asia. The carbonates yielded abundant conodonts, which represent mainly cosmopolitan species but the section differs from most sections in Europe in showing relatively high numbers of Palmatolepis linguiformis species. Deposition through the F/F boundary interval reported here for the Xom Nha section appears to have occurred during a ~1.2 Ma, and shows well-defined climate cyclicity.
    Description: NAFOSTED
    Description: German Science Foundation
    Description: Project for Collecting Paleontological Specimens in Vietnam
    Keywords: ddc:560 ; Microfacies ; Conodonts ; Magnetic susceptibility ; Late Devonian events ; Milankovitch cycles
    Language: English
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  • 22
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    The sustainability of beach nourishments: a review of nourishment and environmental monitoring practice (2021)
    Staudt, Franziska ; Gijsman, Rik ; Ganal, Caroline ; [et al.]
    Springer Netherlands
    Details
    Publication Date: 2023-09-13
    Description: Beach nourishments are a widely used method to mitigate erosion along sandy shorelines. In contrast to hard coastal protection structures, nourishments are considered as soft engineering, although little is known about the cumulative, long-term environmental effects of both marine sediment extraction and nourishment activities. Recent endeavours to sustain the marine ecosystem and research results on the environmental impact of sediment extraction and nourishment activities are driving the need for a comprehensive up-to-date review of beach nourishment practice, and to evaluate the physical and ecological sustainability of these activities. While existing reviews of nourishment practice have focused on the general design (motivation, techniques and methods, international overview of sites and volumes) as well as legal and financial aspects, this study reviews and compares not only nourishment practice but also the accompanying assessment and monitoring of environmental impacts in a number of developed countries around the world. For the study, we reviewed 205 openly-accessible coastal management strategies, legal texts, guidelines, EIA documents, websites, project reports, press releases and research publications about beach nourishments in several developed countries around the world (Germany, Denmark, the Netherlands, Belgium, Spain, UK, USA and Australia). Where information was not openly available, the responsible authorities were contacted directly. The study elaborates on the differences in coastal management strategies and legislation as well as the large dissimilarities in the EIA procedure (where applicable) for both marine sediment extraction and nourishment activities. The spatial disturbance of the marine environment that is considered a significant impact, a factor which determines the need for an Environmental Impact Assessment, varies substantially between the countries covered in this study. Combined with the large uncertainties of the long-term ecological and geomorphological impacts, these results underline the need to reconsider the sustainability of nourishments as “soft” coastal protection measures.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:627.5 ; Coastal protection ; Coastal management ; Beach nourishment ; Sustainability ; Ecology ; Environmental impact assessment
    Language: English
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  • 23
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    Seismotectonics of the Blanco Transform Fault System, Northeast Pacific: Evidence for an Immature Plate Boundary (2023)
    Details
    Publication Date: 2023-09-13
    Description: At the Blanco transform fault system (BTFS) off Oregon, 138 local earthquakes and 84 double‐couple focal mechanisms from ocean‐bottom‐seismometer recordings jointly discussed with bathymetric features reveal a highly segmented transform system without any prominent fracture zone traces longer than 100 km. In the west, seismicity is focused at deep troughs (i.e., the West and East Blanco, and Surveyor Depressions). In the east, the BTFS lacks a characteristic transform valley and instead developed the Blanco Ridge, which is the most seismically active feature, showing strike‐slip and dip‐slip faulting. Sandwiched between the two main segments of the BTFS is the Cascadia Depression, representing a short intra‐transform spreading segment. Seismic slip vectors reveal that stresses at the eastern BTFS are roughly in line with plate motion. In contrast, stresses to the west are clockwise skewed, indicating ongoing reorganization of the OTF system. As we observed no prominent fracture zones at the BTFS, plate tectonic reconstructions suggest that the BTFS developed from non‐transform offsets rather than pre‐existing transform faults during a series of ridge propagation events. Our observations suggest that the BTFS can be divided into two oceanic transform systems. The eastern BTFS is suggested to be a mature transform plate boundary since ∼0.6 Ma. In contrast, the western BTFS is an immature transform system, which is still evolving to accommodate far‐field stress change. The BTFS acts as a natural laboratory to yield processes governing the development of oceanic transform faults.
    Description: Plain Language Summary: The Blanco transform fault system (BTFS) northwest off the coast of Oregon is seismically very active. We used 1 year of ocean bottom seismometer data collected between September 2012 and October 2013 to locate 138 local earthquakes. The events align perfectly with the morphologic features of the BTFS, dividing the BTFS into five transform segments and two short intra‐transform spreading centers. Furthermore, we observe different seismotectonic behaviors of the western and eastern BTFS based on the along‐strike variation in morphology, magnetization, focal depth distribution, and strain partitioning. Although many segmented oceanic transform systems were formed from a single transform fault in response to rotations in plate motion, the BTFS turns out to be originated from non‐transform offsets between ridge segments, as we observed no prominent fracture zone traces neither in morphology nor gravity field data. A clockwise shift in the Juan de Fuca/Pacific pole of rotation at ∼5 Ma followed by a series of ridge propagation events initiated the formation of the BTFS, integrated each segment of the BTFS by shortening the ridge segments in between. Our observations suggest that the Blanco Ridge and the Gorda transform segment in the eastern BTFS were formed at ∼1.6 and 0.6 Ma, respectively, and ever since, the eastern BTFS became a mature transform boundary. In contrast, seismic slip vectors comparing to plate motion directions reveal that stresses in the western BTFS are systematically skewed, suggesting the immature transform plate boundary is still adjusting to the new stress regime.
    Description: Key Points: Local seismicity of the Blanco transform fault system (BTFS) reveals along‐strike variations dominated by strike‐slip and oblique dip‐slip. The BTFS developed from non‐transform offsets rather than discrete transform faults in response to plate rotation and ridge propagation. The BTFS consists of a mature plate boundary in the east and an immature system in the west, separated by a central spreading center.
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: https://doi.org/10.7914/SN/X9_2012
    Description: https://www.gmrt.org/GMRTMapTool/
    Description: https://mrdata.usgs.gov/magnetic/
    Keywords: ddc:551.22 ; Blanco transform fault system ; local seismicity ; tectonic evolution ; transform plate boundary
    Language: English
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  • 24
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    Bayesian Quantification and Reduction of Uncertainties in 3D Geomechanical‐Numerical Models (2022)
    Details
    Publication Date: 2023-09-13
    Description: The distance to failure of the upper crustal rock in the prevalent stress field is of importance to better understand fault reactivation by natural and induced processes as well as to plan and manage georeservoirs. In particular, the contemporary stress state is one of the key ingredients for this assessment. To provide a continuous description of the 3D absolute stress state geomechanical‐numerical models are used. However, stress magnitude data for model calibration are sparse and incomplete and thus, the resulting model uncertainties are large. In order to reduce the uncertainties, we incorporate additional constraints on stress magnitudes to check the plausibility of different data‐based stress states. We use formation integrity tests, borehole breakouts, drilling induced fractures, and observations of seismicity and distinct seismological quiescence. This information is weighted according to its confidence and the agreement with the different modeled stress states is assessed. The information is introduced to a Bayesian approach to estimate weights of the modeled stress states and thereby identify their plausibility. A case study in southern Germany shows the ability of the approach to identify from a wide range of stress states a small number of plausible ones and reject implausible stress states. This significantly reduces the number of stress states and thus lowers the model uncertainties.
    Description: Plain Language Summary: The upper crust of the Earth (upper few kilometers) is subject to a kind of pressure, referred to as stress. When the stress becomes larger than the strength of the rock, the rock breaks. Sometimes this can be measured or even felt as a seismic event. It happens naturally but may also happen due to human activity. To prevent such induced seismic event, it is important to know the stress state. But there is only few information on the magnitude of the stress so we need computer models to predict the stress state. These models are often not very precise since there is only few information on the stress magnitudes and in addition they are often contradicting. We use all stress magnitude information individually to model various stress states. Then we look at other information that is related to the stress state but does not provide stress magnitude information on its own. We compare this information with the modeled stress states to find out whether a stress state agrees with the additional information or not. This allows us to identify a few realistic stress state models out of a wide range of possible ones. This reduces the uncertainties of the stress predictions.
    Description: Key Points: Bayesian approach to uncertainty quantification and reduction of 3D geomechanical‐numerical models of the undisturbed stress state. Additional constraints on the stress state by formation integrity tests, borehole breakouts, and drilling induced tensile fractures. Constraints on the differential stress by observation of seismicity or distinct seismological quiescence.
    Description: Bundesministerium für Bildung, Wissenschaft und Forschung http://dx.doi.org/10.13039/501100013699
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Helmholtz Centre Potsdam ‐ Deutsches GeoForschungsZentrum GFZ
    Description: RI Fabrice Cotton
    Description: Federal Company for radioactive waste disposal
    Description: https://github.com/MorZieg/FAST_Calibration
    Keywords: ddc:550 ; geomechanics ; uncertainties ; stress state ; modeling ; Bayes
    Language: English
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  • 25
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    Interdecadal Pacific Oscillation in Northern Greenland Dust Concentration Variability During the Last 400 Years (2022)
    Details
    Publication Date: 2023-09-13
    Description: Statistical analysis of reanalysis and observed data reveals that high dust surface mass concentration in northern Greenland is associated with a Pacific Decadal Oscillation like pattern in its negative phase in the North Pacific as well as with La Niña conditions in the tropical Pacific region. The sea surface temperature anomalies in the Pacific realm resemble the Interdecadal Pacific Oscillation (IPO). The associated atmospheric circulation pattern, in the form of a wave‐train from the North Pacific to the Eurasian continent, favors enhanced dust uptake and transport toward the northern Greenland. Similar patterns are associated with a low‐resolution stacked record of five Ca2+ ice cores, that is, ngt03C93.2 (B16), ngt14C93.2 (B18), ngt27C94.2 (B21), GISP2−B, and NEEM‐2011‐S1, from northern Greenland, a proxy for regional dust concentration, during the last 400 years. We argue that northern Greenland ice core dust records could be used as proxies for the IPO and related teleconnections.
    Description: Plain Language Summary: Observational and modeling studies show that, during the observational period, interannual to multidecadal dust concentration variability is related to the dominant modes of climate variability at these time scales. Here we show that Interdecadal Pacific Oscillation (IPO) signal is robustly recorded in low‐resolution dust ice core records from the northern Greenland during the last 400 years. We argue that northern Greenland ice core dust records could be used to put the IPO activity and related teleconnections during the observational period into a long‐term perspective.
    Description: Key Points: Northern Greenland dust concentration variability shows global teleconnections during the instrumental period. The most stable pattern associated with northern Greenland ice core dust variability is the Interdecadal Pacific Oscillation (IPO). Northern Greenland ice core dust records could be used as a complementary source of information about IPO during the past.
    Description: Changing Earth—Sustaining our Future
    Description: Helmholtz Climate Initiative—REKLIM
    Description: https://doi.org/10.1594/PANGAEA.57092
    Description: https://doi.org/10.1594/PANGAEA.57294
    Description: https://doi.org/10.1594/PANGAEA.107285
    Description: https://doi.org/10.1594/PANGAEA.55536
    Description: https://disc.gsfc.nasa.gov/datasets?project=MERRA-2
    Description: https://psl.noaa.gov/data/gridded/data.cobe.html
    Description: https://psl.noaa.gov/data/gridded/data.20thC_ReanV2c.html
    Description: https://www.ncdc.noaa.gov/paleo-search/study/33092
    Description: https://www.wdc-climate.de/ui/entry?acronym=EKF400_v2.0
    Keywords: ddc:551.6 ; dust concentration ; northern Greenland ; Interdecadal Pacific Oscillation ; ice cores
    Language: English
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  • 26
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    Early Holocene aeolian sediments in southwestern Crete−preliminary results (2021)
    Springer International Publishing
    Details
    Publication Date: 2023-09-13
    Description: The soilscapes along the southern and western coast of Crete (Greece) are dominated by coarse-grained reddish-brown slope sediments whose natural (pre-anthropogenic) configuration and properties are difficult to reconstruct due to the long history of intense land use. As a consequence, datable terrestrial sediment archives of pre-anthropogenic genesis are scarce. We present preliminary results of a study performed on an accumulation within an alluvial fan south of Stomio Bay in southwestern Crete. The studied profile is located in a small depression and is composed of a sequence of sandy to silty yellowish-brown calcareous sediments overlying coarse-grained slope sediments, including a fossil topsoil horizon. Based on macroscopic, micromorphological, geochemical, geophysical and mineralogical analysis, we interpret the fine-grained sediments to have a local aeolian origin. OSL dating indicates a final deposition phase during the early Holocene. Considering the scarcity of early Holocene terrestrial archives in Crete, the analysed profile provides valuable data for the reconstruction of landscape dynamics and paleoecological conditions as well as soil-sediment configurations during this time period. Additional research is needed to address the specific source area(s) as well as the ages of the deposition of slope sediments and formation of the fossil topsoil.
    Description: Freie Universität Berlin (1008)
    Keywords: ddc:551.3 ; Aeolian sediments ; Fossil soil ; Early Holocene ; Crete ; Eastern Mediterranean
    Language: English
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  • 27
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    Magnetic Fields and Plasma Motions in a Hybrid Martian Magnetosphere (2023)
    Details
    Publication Date: 2023-09-13
    Description: The Martian magnetosphere contains elements of induced and intrinsic origin. To display them one must use different coordinate systems. Although the solar‐electric coordinate system (Mars Solar Electric [MSE]) adequately describes the main features of the induced magnetosphere, it removes/suppresses aspects caused by the crustal magnetic sources while rotating the spacecraft position to the MSE‐coordinate system and averaging over many orbits. On the other hand, to observe effects of the crustal field one should use the solar orbital coordinates (Mars Solar Orbital [MSO]). To find a compromise and keeping in mind that the most probable value of the clock angle of the interplanetary magnetic field (IMF) on the Mars orbit is ∼90° we can consider separately cases with positive and negative B〈sub〉y〈/sub〉 components of the IMF. It is shown that dynamics of ion fluxes in the distant regions of the magnetosphere is mainly controlled by induced features. However, reconnection of the draping IMF with crustal field leads to a twisting of the classical draping configuration. Despite of the very intricate local geometry of the crustal field, the low‐order harmonics of the magnetic field and mainly the dipole component determine the reconnection sites, at least, statistically for many Mars rotations. For different signs of the By component of the IMF these sites occur either in the +Y‐MSO or −Y‐MSO hemispheres. As a result, statistically the magnetosphere of Mars looks like a hybrid magnetosphere formed during the solar wind interaction with the obstacle which simultaneously contains an extended ionosphere and a weak dipole magnetic field.
    Description: Key Points: The Martian magnetosphere contains elements of induced and intrinsic origin. Dynamics of ion fluxes in the magnetic tail, is mainly controlled by induced features. Reconnection of the interplanetary magnetic field with low‐order harmonics of the crustal field leads to twisting of the tail and formation of hybrid magnetosphere.
    Description: DFG
    Description: https://pds-ppi.igpp.ucla.edu/mission/MAVEN
    Keywords: ddc:523 ; Martian magnetosphere
    Language: English
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  • 28
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    Projecting Stratocumulus Transitions on the Albedo—Cloud Fraction Relationship Reveals Linearity of Albedo to Droplet Concentrations (2022)
    Details
    Publication Date: 2023-09-13
    Description: Satellite images show solid marine stratocumulus cloud decks (Sc) that break up over the remote oceans. The Sc breakup is initiated by precipitation and is accompanied by a strong reduction in the cloud radiative effect. Aerosol has been shown to delay the Sc breakup by postponing the onset of precipitation, however its climatic effect is uncertain. Here we introduce a new approach that allows us to re‐cast currently observed cloud cover and albedo to their counterfactual cleaner world, enabling the first estimate of the radiative effect due to delayed cloud breakup. Using simple radiative approximation, the radiative forcing with respect to pre‐industrial times due to delayed Sc breakup is −0.39 W m−2. The radiative effect changes nearly linearly with aerosol due to the droplet concentration control on the cloud cover, suggesting a potentially accelerated warming if the current trend of reduction in aerosol emissions continues.
    Description: Plain Language Summary: The response of cloud cover to aerosol is a climatologically important quantity that has been extremely difficult to estimate. The challenge is that one would need to estimate the fractional area that is currently overcast, but which would have been partly overcast in a cleaner atmosphere. Global climate models (GCMs) are one tool to address such a problem. They allow one to change aerosol levels and to evaluate the cloud response. However, representation of warm, low‐level cloud processes, and in particular aerosol‐cloud interactions in GCMs, is inadequate. Here we introduce an observational method that allows us to re‐cast the currently observed cloud cover and albedo of oceanic warm clouds to their counterfactual state in a cleaner world. We find a linear relationship between the cloud radiative effect and droplet concentration. If we continue to experience a decrease in aerosol emissions then we anticipate a reduction in the aerosol‐cloud radiative effect. The global annual radiative forcing associated with anthropogenic aerosol delaying closed cell breakup is found to be −0.39 W m−2.
    Description: Key Points: A simple model is presented to describe closed cell breakup by initiation of precipitation. The model demonstrates that the global annual radiative effect due to delayed closed cells breakup changes nearly linearly with emissions. The linearity emerges from the nearly linear relationship between cloud cover and albedo.
    Description: German Research Foundation
    Description: Department of Energy's Atmospheric System Research
    Description: Royal Society University Research Fellowship
    Description: https://ladsweb.modaps.eosdis.nasa.gov/archive/allData/61/MOD06_L2/
    Description: https://ceres-tool.larc.nasa.gov/ord-tool/jsp/SSF1degEd41Selection.jsp
    Description: https://doi.org/10.24381/cds.bd0915c6
    Description: https://doi.org/10.5281/zenodo.7072605
    Keywords: ddc:551.5 ; cloud radiative effect ; stratocumulus ; aerosol cloud interactions ; transitions ; closed cells ; open cells
    Language: English
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    The composition of CI chondrites and their contents of chlorine and bromine: Results from instrumental neutron activation analysis (2021)
    Details
    Publication Date: 2023-09-13
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Between 1973 and 1994, 15 samples of CI chondrites were analyzed by neutron activation analysis at the Max‐Planck‐Institute for Chemistry, Department of Cosmochemistry in Mainz, Germany. The analyses comprise nine Orgueil samples and three samples of Ivuna, two of Alais and one of Tonk. Samples came from various sources and had masses between 5 and 600 mg. Most data are published here for the first time. The results for the nine Orgueil samples demonstrate the essentially homogeneous chemical composition of Orgueil at a level of a few milligrams. The analytical results of Ivuna, Alais, and Tonk agree, with only few exceptions, with the results of Orgueil analyses. All samples agree within ±3% in their contents of Sc, Ir, Cr, Fe, Co, Zn, and Se. The elements Sc and Ir represent the refractory component; Cr, Fe, and Co the main component; and Zn and Se the volatile component. Thus, in all CI chondrites there are essentially the same fractions of the fundamental cosmochemical components. The essentially identical chemical composition of all samples shows that their water contents are constant at about 20 ± 5 wt%. There is excellent agreement between the data listed here with data reported in the relevant literature. There is no doubt that the CI composition is a well‐defined entity, which is thought to represent the non‐gaseous compositions of the solar nebula and the photosphere of the Sun. In addition, we conclude that the recently proposed new CI chondritic chlorine and Br values are too low, when compared to earlier measurements.〈/p〉
    Keywords: ddc:551.9 ; CI chondrites ; composition ; chlorine ; bromine ; neutron activation analysis
    Language: English
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    Atmospheric CO2 Concentration Based on Boron Isotopes Versus Simulations of the Global Carbon Cycle During the Plio‐Pleistocene (2023)
    Details
    Publication Date: 2023-09-13
    Description: Atmospheric carbon dioxide concentrations (pCO〈sub〉2〈/sub〉) beyond ice core records have been reconstructed from δ〈sup〉11〈/sup〉B derived from planktic foraminifera found in equatorial sediment cores. Here, I applied a carbon cycle model over the Plio‐Pleistocene to evaluate the assumptions leading to these numbers. During glacials times, simulated atmospheric pCO〈sub〉2〈/sub〉 was unequilibrated with pCO〈sub〉2〈/sub〉 in the equatorial surface ocean by up to 35 ppm while the δ〈sup〉11〈/sup〉B‐based approaches assume unchanged (quasi)equilibrium between both. In the Pliocene, δ〈sup〉11〈/sup〉B‐based estimates of surface ocean pH are lower in the Pacific than in the Atlantic resulting in higher calculated pCO〈sub〉2〈/sub〉. This offset in pH between ocean basins is not supported by models. To calculate pCO〈sub〉2〈/sub〉 in surface waters out of the δ〈sup〉11〈/sup〉B‐based pH some assumptions on either total alkalinity or dissolved inorganic carbon are necessary. However, the assumed values of these under‐constrained variables were according to my results partly inconsistent with chemically possible combinations within the marine carbonate system. The model results show glacial/interglacial variability in total alkalinity of the order of 100 μmol/kg, which is rarely applied to proxy reconstructions. Simulated atmospheric pCO〈sub〉2〈/sub〉 is tightly (r〈sup〉2〈/sup〉 〉 0.9) related to equatorial surface‐ocean pH, which can be used for consistency checks. Long‐term trends in volcanic CO〈sub〉2〈/sub〉 outgassing and the strength of the continental weathering fluxes are still unconstrained, allowing for a wide range of possible atmospheric pCO〈sub〉2〈/sub〉 across the Plio‐Pleistocene. Nevertheless, this carbon cycle analysis suggests that reported atmospheric pCO〈sub〉2〈/sub〉 above 500 ppm in the Pliocene might, for various reasons, need to be revised to smaller numbers.
    Description: Key Points: Simulated equatorial surface ocean 𝑝CO〈sub〉2〈/sub〉 is near‐equilibrium with atmosphere during interglacials but enriched (≤35 ppm) during glacials. Models suggest similar equatorial surface 𝑝H in Pacific and in Atlantic in high CO〈sub〉2〈/sub〉 worlds while Pliocene reconstructions show offsets. Carbon cycle model analysis suggests that reported CO〈sub〉2〈/sub〉 values above 500 ppm in the Pliocene might need revisions to smaller numbers.
    Keywords: ddc:551 ; carbon cycle ; modeling ; CO2 ; boron isotopes ; pH ; Plio‐Pleistocene
    Language: English
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    Temporal Variability of Fluvial Sand Composition: An Annual Time Series From Four Rivers in SW Germany (2023)
    Details
    Publication Date: 2023-09-13
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The sampling of fluvial sediment is subject to many sources of uncertainty, for example, time and location, and the number of samples collected. It is nevertheless commonly assumed that a sample taken at one time and location provides a somewhat averaged compositional signal. Any spatial or temporal variability of this signal is often neglected. This study investigates how the composition of bed load sand changes over an observation period of 1 year in four river basins with differing bedrock geology in southwestern Germany. Up to 12 bulk sediment samples were taken at the same locations using the same approach and analyzed for their granulometry and geochemistry. The results indicate that (a) different grain sizes yield different compositions due to source rock composition and hydraulic sorting effects, (b) bulk sediment composition changes temporally due to changing grain‐size distribution, and (c) compared to the bulk sample, the composition of narrow grain sizes is temporally more stable but nevertheless has an average variability of 15%. Because heavy mineral‐bound elements such as Zr have the highest variability, we relate a major component of compositional variability to temporally varying heavy mineral concentrations in response to hydrodynamic processes. Mixing modeling demonstrates that the fluvial sand faithfully reflects its catchment geology and that the sediment sources do not change substantially during the observation period, even during a flooding event. We conclude (a) that the causes for compositional variability may be disentangled using chemical and granulometric time series data and (b) that narrow grain sizes yield representative source rock contributions.〈/p〉
    Description: Plain Language Summary: Sediment transported by rivers is generated by the erosion of the rocks present within the river catchment area. The composition of this sediment is controlled by various processes in the catchment, for example, climate, rock type, weathering, and flow strength. Geoscientists can use modern river sediment to understand how these processes impact sediment composition, and then apply this information to the geologic time. Sampling the river sediment is often the first step in such studies, but few studies consider the sources of uncertainty during sampling, for example, time and location of sampling, and number of collected samples. For this study, we returned to the same river location during the course of 1 year to take bulk sediment samples and analyzed how variable the size of sediment grains and the sediment chemistry are. We discovered that different grain sizes yield different chemical compositions, and this is caused by differences in rock type and hydraulic processes. Because the proportion of different grain sizes in the bulk sediment changes over the year due to water flow conditions, the chemistry of the bulk sediment sample changes over the year. We provide some quantitative estimates for this variability that should be considered in similar studies.〈/p〉
    Description: Key Points: Bed load sand from 4 rivers was sampled monthly over the course of 1 year to analyze the temporal compositional variability. Composition is grain‐size‐dependent, and narrow grain‐size fractions show less variability than bulk sediment samples. Composition changes during the year, and this is related to changing grain‐size distributions rather than changing sediment sources.
    Description: https://doi.pangaea.de/10.1594/PANGAEA.959006
    Keywords: ddc:551.9 ; geochemistry ; provenance ; grain‐size ; variability ; bed load ; fluvial sediment
    Language: English
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    Empirical assessment of rockfall and debris flow risk along the Karakoram Highway, Pakistan (2021)
    Springer Netherlands
    Details
    Publication Date: 2023-09-14
    Description: The Karakoram Highway links north Pakistan with southwest China. It passes through unique geomorphological, geological and tectonic setting. This study focused 200-km-long section of the highway starting from Besham until Chilas. Landslides are frequent and are mostly triggered by torrential rain during Monsoon and Westerlies, leading to highway blockade. Rockfall and debris flow are prime mode of slope failures. Regional to site-specific approach was implemented to assess risk associated with these two modes. Remote sensing-based techniques were used to identify potential hazardous sites, which were further investigated for risk assessment. Modified Pierson’s rockfall hazard rating system (RHRS) rated potential rockfalls, whereas semi-quantitative technique was employed to assess debris flows. Normalized scores of each site shaped the final map, further classified into four zones: very high, high, intermediate and low risk.
    Description: Higher Education Commission, Pakistan (PK)
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Projekt DEAL
    Keywords: ddc:551.3 ; Risk assessment ; Landslide ; Rockfall ; Debris flow ; Karakoram Highway
    Language: English
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    Plane strain shear strength of unsaturated fiber-reinforced fine-grained soils (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: Discrete randomly distributed fibers are commonly used to improve the engineering characteristics of the soil and thus soil properties such as shear strength, compressibility, density, and hydraulic conductivity. Most studies have so far focused on describing the behavior of soils containing randomly distributed fibers under dried or saturated conditions. However, the water table may seasonally fluctuate, thus generating unsaturated soil conditions. Therefore, a better understanding of the hydro-mechanical properties of unsaturated improved soils is of high necessity. In this research, the shear strength parameters of fine-grained soils were evaluated using the biaxial device available at Ruhr Universität Bochum. The applied device was modified to test unsaturated fine-grained soils with various degrees of saturation using axis translation and vapor equilibrium techniques. The experiments were conducted on fine soils containing 0, 0.5, and 1% fiber contents under a wide range of matric suctions. The ductile behavior was more noticeable in samples with lower suctions and higher straw contents. Furthermore, the shear strength of both unreinforced and reinforced fine-grained soils considerably increased by an increase in the suction. Finally, shear band inclination increased by the suction while decreasing by straw content.
    Description: Ruhr-Universität Bochum (1007)
    Keywords: ddc:550.78 ; Plane strain condition ; Shear strength ; Soil reinforcement ; Suction ; SWCC
    Language: English
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    Marble decay: towards a measure of marble degradation based on ultrasonic wave velocities and thermal expansion data (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: Marble as ornamental and dimensional stones as well as in their natural environments show complex weathering phenomena. Physical, chemical, and biological weathering of marble are well documented. The impact of climate change on monuments and historic buildings in terms of modeling and predicting future scenarios requires new approaches to forecast the ongoing decay in the near and far future. Ultrasonic wave velocities are a powerful and sensitive tool for the damage assessment of marble. For a maximum porosity of up to 1%, ultrasonic wave velocities (P-wave velocities) are ranging between 1 km/s and over 6 km/s. Water saturation has an important influence on the magnitude and directional dependence of ultrasonic wave velocities together with the mineralogical composition and the rock fabrics. Ongoing experimental alteration approaches were used to document the state of deterioration using Vp-systematics. In addition, thermal expansion and the residual strain values after applying thermal impacts were used to introduce a new quantitative measure based on experimental length changes and volume changes. To quantify such volume changes, a so-called decay index was proposed. Marbles are sensitive to weathering and have different volume changes under exposure depending on fabric parameters. The volume extension index of marble, based on thermal expansion measurements under dry and water-saturated conditions, is proposed as a decay index for quantifying sample stability and for defining the directions of maximum and minimal dilatation. Such decay index was implemented to different marble types and it was turned out that marbles with the larger decay indexes are more prone to weathering than with smaller ones. The effect of changing climate and, in consequence, different weathering actions can help to calculate or forecast risk numbers based on the Vp data in combination with the proposed decay index especially for marbles.
    Description: Georg-August-Universität Göttingen (1018)
    Keywords: ddc:552 ; Marble decay ; Ultrasonic wave velocities ; Thermal expansion ; Risk assessment ; Climate change and deterioration
    Language: English
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    GeomInt: geomechanical integrity of host and barrier rocks–experiments, models and analysis of discontinuities (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: The present paper gives an overview of the GeomInt project “Geomechanical integrity of host and barrier rocks—experiment, modelling and analysis of discontinuities” which has been conducted from 2017–2020 within the framework of the “Geo:N Geosciences for Sustainability” program. The research concept of the collaborative project is briefly introduced followed by a summary of the most important outcomes. The research concept puts geological discontinuities into the centre of investigations—as these belong to the most interesting and critical elements for any subsurface utilisation. Thus, while research questions are specific, they bear relevance to a wide range of applications. The specific research is thus integrated into a generic concept in order to make the results more generally applicable and transferable. The generic part includes a variety of conceptual approaches and their numerical realisations for describing the evolution of discontinuities in the most important types of barrier rocks. An explicit validation concept for the generic framework was developed and realised by specific “model-experiment-exercises” (MEX) which combined experiments and models in a systematic way from the very beginning. 16 MEX have been developed which cover a wide range of fundamental fracturing mechanisms, i.e. swelling/shrinkage, fluid percolation, and stress redistribution processes. The progress in model development is also demonstrated by field-scale applications, e.g. in the analysis and design of experiments in underground research laboratories in Opalinus Clay (URL Mont Terri, Switzerland) and salt rock (research mine Springen, Germany).
    Description: BMBF
    Description: Helmholtz-Zentrum für Umweltforschung GmbH - UFZ (4215)
    Keywords: ddc:550.724 ; GeomInt ; Fracture flow ; Fracture mechanics ; Barrier integrity ; Discontinuities ; Open source ; OpenGeoSys
    Language: English
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    Crustal architecture of a metallogenic belt and ophiolite belt: implications for mineral genesis and emplacement from 3-D electrical resistivity models (Bayankhongor area, Mongolia) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: Crustal architecture strongly influences the development and emplacement of mineral zones. In this study, we image the crustal structure beneath a metallogenic belt and its surroundings in the Bayankhongor area of central Mongolia. In this region, an ophiolite belt marks the location of an ancient suture zone, which is presently associated with a reactivated fault system. Nearby, metamorphic and volcanic belts host important mineralization zones and constitute a significant metallogenic belt that includes sources of copper and gold. However, the crustal structure of these features, and their relationships, are poorly studied. We analyze magnetotelluric data acquired across this region and generate three-dimensional electrical resistivity models of the crustal structure, which is found to be locally highly heterogeneous. Because the upper crust (〈 25 km) is found to be generally highly resistive (〉 1000 Ωm), low-resistivity (〈 50 Ωm) features are conspicuous. Anomalous low-resistivity zones are congruent with the suture zone, and ophiolite belt, which is revealed to be a major crustal-scale feature. Furthermore, broadening low-resistivity zones located down-dip from the suture zone suggest that the narrow deformation zone observed at the surface transforms to a wide area in the deeper crust. Other low-resistivity anomalies are spatially associated with the surface expressions of known mineralization zones; thus, their links to deeper crustal structures are imaged. Considering the available evidence, we determine that, in both cases, the low resistivity can be explained by hydrothermal alteration along fossil fluid pathways. This illustrates the pivotal role that crustal fluids play in diverse geological processes, and highlights their inherent link in a unified system, which has implications for models of mineral genesis and emplacement. The results demonstrate that the crustal architecture—including the major crustal boundary—acts as a first‐order control on the location of the metallogenic belt.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung http://dx.doi.org/10.13039/501100001711
    Description: Westfälische Wilhelms-Universität Münster (1056)
    Keywords: ddc:553 ; Metallogenic belt ; Ophiolite belt ; Fault zone ; Mineralization ; Mineral emplacement ; Electrical resistivity
    Language: English
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    Central Asian modulation of Northern Hemisphere moisture transfer over the Late Cenozoic (2021)
    Prud’homme, Charlotte ; Scardia, Giancarlo ; Vonhof, Hubert ; [et al.]
    Nature Publishing Group UK
    Details
    Publication Date: 2023-09-14
    Description: Earth’s climatic evolution over the last 5 million years is primarily understood from the perspective of marine mechanisms, however, the role of terrestrial feedbacks remains largely unexplored. Here we reconstruct the last 5 million years of soil moisture variability in Central Asia using paleomagnetism data and isotope geochemistry of an 80 m-thick sedimentary succession at Charyn Canyon, Kazakhstan. We identify a long-term trend of increasing aridification throughout the period, along with shorter-term variability related to the interaction between mid-latitude westerlies and the Siberian high-pressure system. This record highlights the long-term contribution of mid-latitude Eurasian terrestrial systems to the modulation of moisture transfer into the Northern Hemisphere oceans and back onto land via westerly air flow. The response of Earth-surface dynamics to Plio-Pleistocene climatic change in Central Asia likely generated terrestrial feedbacks affecting ocean and atmospheric circulation. This missing terrestrial link elucidates the significance of land-water feedbacks for long-term global climate.
    Description: Late Cenozoic variation in Central Asian hydroclimate resulted from the interaction between mid-latitude westerlies and the Siberian high-pressure system and may have driven terrestrial feedbacks, according to analyses of sediments from Charyn Canyon, Kazakhstan.
    Description: Palaeomagnetic, rock magnetic and grain-size analyses were funded by the grant CNPq
    Description: Deutsche Forschungsgemeinschaft (German Research Foundation) https://doi.org/10.13039/501100001659
    Description: Wilhelm und Else Heraeus-Stiftung (Wilhelm and Else Heraeus Foundation) https://doi.org/10.13039/501100011618
    Description: https://doi.org/10.17632/v9s3bhn27k.1
    Keywords: ddc:551.6 ; palaeoclimate ; Charyn Canyon sequence ; Kazakhstan ; isotope geochemistry ; paleomagnetism
    Language: English
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    Black Sea hydroclimate and coupled hydrology was strongly controlled by high-latitude glacial climate dynamics (2021)
    Nature Publishing Group UK
    Details
    Publication Date: 2023-09-14
    Description: Abstract The Black Sea experienced pronounced millennial-scale changes in temperature and rainfall during the last glacial coinciding with Dansgaard-Oeschger cycles. However, little is known regarding the amount and sources of freshwater reaching this inland basin. Here, we present detailed ostracod δ〈sup〉18〈/sup〉O data from the glacial Black Sea showing subdued Dansgaard-Oeschger cyclicity and four prominent longer-term saw-tooth shaped Bond-like cycles. We propose that the δ〈sup〉18〈/sup〉Oostracods signature primarily reflects changes in the atmospheric circulation in response to the waxing and waning Eurasian Ice Sheet. The millennial-scale ice sheet variations likely resulted not only in latitudinal migrations of atmospheric frontal systems but also in shifts of dominant moisture sources for the Black Sea. Heavier isotopic precipitation arrived from the North Atlantic-Mediterranean realm during the warmer interstadials and lighter isotopic precipitation from the Eurasian continental interior during the colder stadials. The subdued Dansgaard-Oeschger variability likely reflects an integrated precipitation signal additionally affected by the long mixing times of the large Black Sea volume up to 1,500 years as suggested from hydrologic-isotope-balance modelling.
    Description: Moisture sources to the Black Sea changed in response to atmospheric frontal displacements driven by Eurasian Ice Sheet dynamics during the last glacial period, according to analyses of ostracod oxygen and strontium isotope data from Black Sea sediments.
    Description: Deutsche Forschungsgemeinschaft (German Research Foundation) https://doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.4545579
    Keywords: ddc:551 ; paleohydrology ; palaeoclimate ; Black Sea ; Archangelsky Ridge ; isotope geochemistry ; Dansgaard-Oeschger cycles
    Language: English
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    Hydrochemistry and environmental isotopes (18O, 2H, 3H, 3He/4He) of groundwater and floodwater in the great area of Hurghada, Eastern Desert of Egypt (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: Porous and fractured aquifers exist in the area of Hurghada, Eastern Desert of Egypt, whose recharge processes through the common flash floods are not identified. Hydrochemical parameters, stable isotopes 〈sup〉18〈/sup〉O, 〈sup〉2〈/sup〉H and tritium in floodwater and groundwater were applied in the area subject to study. Additionally, He isotopes were investigated in the deep wells in the faulted zone at the Abu Shaar Plateau. 〈sup〉3〈/sup〉H activity in all sampled points lies below the detection limit excluding a recent recharge component in groundwater. However, the hydrochemical ratios and the stable isotope signature confirm that the shallow wells and springs (Red Sea Hills group) are being recharged from modern precipitation. The hydrochemical parameters of the deep wells at the Abu Shaar Plateau (coastal plain group) confirm another origin for the ions rather than the modern precipitation. Together with the 〈sup〉18〈/sup〉O and 〈sup〉2〈/sup〉H values, the Br/Cl ratio of this group confirms the absence of seawater intrusion component and the role of the fault as a hydraulic barrier. These 〈sup〉18〈/sup〉O and 〈sup〉2〈/sup〉H values deviate from the GMWL confirming an evaporation effect and colder infiltration conditions and reveal strongly a possible mixing with the Nubian Sandstone in the region. The 〈sup〉3〈/sup〉He/〈sup〉4〈/sup〉He ratio confirms a mantle contribution of 2% from the total He components.
    Description: Open Access funding enabled and organized by Projekt DEAL
    Keywords: ddc:551.9 ; Groundwater ; Floodwater ; Hydrochemistry ; Water isotopes ; Helium isotopes ; Eastern desert of Egypt
    Language: English
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    Hydrogen Diffusion in Clinopyroxene at Low Temperatures (195°C–400°C) and Consequences for Subsurface Processes (2022)
    Details
    Publication Date: 2023-09-14
    Description: Studying diffusion of hydrogen in nominally anhydrous minerals, like clinopyroxene, at low temperatures is a challenging task due to experimental and analytical difficulties. In this study, to overcome these problems we have produced H concentration gradients in single crystals of natural diopsidic clinopyroxene by ion implantation and measured the nanoscale profiles before and after diffusion anneals using Nuclear Resonance Reaction Analysis. These steps allowed us to conduct experiments at temperatures between 195°C and 400°C. Obtained diffusion rates show a consistent Arrhenius relation D〈sub〉H〈/sub〉= 5.47(±13.98) · 10−8 · exp (−115.64(±11.5) kJ mol〈sup〉−1〈/sup〉/RT) m〈sup〉2〈/sup〉s〈sup〉−1〈/sup〉. Notably, our results lie well within the range of extrapolations from high temperature experiments (≥600°C) of previous studies. This implies that fast diffusion of hydrogen (compared to other elements) extends to low temperatures. We used these results in a non‐isothermal diffusion model that simulates the ascent of crystals (0.5, 1.0, and 2.0 mm) along two representative P‐T‐paths from 600°C to 100°C, to assess potential re‐equilibration of H contents in clinopyroxene at low temperatures. Our model highlights the need to carefully consider boundary conditions, which are a function of P‐T‐f O〈sub〉2〈/sub〉, that control the concentration gradient at the crystal's rim. The results from this model help to assess, as a function of crystal size and cooling rate, when re‐equilibration must be considered.
    Description: Key Points: Diffusion rates of hydrogen in clinopyroxene in the low temperature range (195°C–400°C) were quantified for the first time. Diffusion coefficients at low temperatures lie within the range of extrapolations from high temperature experiments. Non‐isothermal modeling was applied to evaluate potential re‐equilibration of clinopyroxene crystals at low temperatures.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.7290350
    Keywords: ddc:549 ; diffusion ; hydrogen ; clinopyroxene ; equilibration ; low‐temperature
    Language: English
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    Consolidation of volcanic tuffs with TEOS and TMOS: a systematic study (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-09-14
    Description: In this study, nine volcanic tuffs from Armenia, Germany and Mexico were treated with two commercially available consolidants on base of silicic acid ester, as well as different pretreatments with an anti-swelling agent and/or primer components. Prior to the treatment, the tuffs were analyzed regarding their petrography and mineralogy, with a greater focus on their clay mineral content. The effect of the consolidation was evaluated by comparative analyses of petrophysical properties and weathering behavior before and after the treatments. The main goals of this study were to identify a general suitability of different consolidating treatments for different types of tuff, evaluating tartaric acid as a primer component for tuff consolidation and to pursue the approach of finding a molecular answer for apparent tuff consolidation problematics, by testing a consolidation agent with smaller molecule sizes than current products on the market: tetramethoxysilane (TMOS).
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Volkswagen Foundation http://dx.doi.org/10.13039/501100001663
    Description: Deutsche Bundesstiftung Umwelt http://dx.doi.org/10.13039/100007636
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Georg-August-Universität Göttingen (1018)
    Keywords: ddc:552 ; Consolidation ; TEOS ; TMOS ; Volcanic tuff ; Building stones
    Language: English
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    Promoting FAIR and open data publication at the Department of Earth Sciences, Freie Universität Berlin (2023)
    Details
    Publication Date: 2023-09-18
    Description: The Department of Earth Sciences at Freie Universität Berlin has recently established a concept and workflow for the promotion of research data and its publishing. The project, funded with seed money from central university administration, was developed in close cooperation with the research data management (RDM) team of the university library. A key element in the project is the RDM-team proactively advertising support for data publishing to researchers of the department. This offer is very well received by the researchers, as they are often willing to publish data, but lack time as well as knowledge of best practice in data publication. Several data publishing projects have been kicked-off this way. Another thrust of the project is to feature data publications on the department´s website. This fosters the recognition of data publications as important resarch output of the scientists of the Department of Earth Sciences. The data are presented on the website in an easily accessible and understandable context, to makes them available to potenially new user groups like lay persons, citizen scientists, or pupils. Before published on the website, researchers are asked by the RDM-team to proof-read short descriptive drafts about their data publications, and this opens up a great opportunity for researchers to engage with data publication specialists about best practices and standards of „FAIR and open“ data practices. This project facilitates cultural change towards FAIR and open data publication at an university department and may be used as a blueprint for departments in other universities and research institutions.
    Description: presentation
    Keywords: Research data ; FAIR principles ; Open science
    Language: English
    Type: doc-type:conferenceObject
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    Drei Jahrzehnte elektromagnetische Meereisdickenmessungen für die Klimaforschung (2023)
    Details
    Publication Date: 2023-11-30
    Description: DFG, SUB Göttingen
    Description: research
    Keywords: Meereis ; Elektromagnetik
    Language: German
    Type: doc-type:article
    Format: 5
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    Computational methods for the analysis of climate change communication: Towards an integrative and reflexive approach (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-05
    Description: Computational methods, in particular text‐as‐data or Natural Language Processing (NLP) approaches, have become popular to study climate change communication as a global and large‐scale phenomenon. Scholars have discussed opportunities and challenges of these methods for climate change communication, with some proponents and critics taking strong positions, either embracing the potential of computational methods or critically questioning their value. Mirroring developments in the broader social scientific debate, we aim to bring both sides together by proposing a reflexive, integrative approach for computational research on climate change communication: We reflect on strengths (e.g., making data big and small, nowcasting observations) and weaknesses (e.g., introducing empiricist epistemologies, ignoring biases) of computational approaches. Moreover, we also provide concrete and constructive guidance on when and how to integrate (or not integrate) these methods based on theoretical considerations. We thereby understand computational methods as part of an ever‐increasing, diverse toolbox for analyzing climate change communication.
    Keywords: ddc:304.28 ; big data ; climate change communication ; computational methods ; news media ; social media
    Language: English
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    Minimal Recipes for Global Cloudiness (2022)
    Details
    Publication Date: 2023-12-05
    Description: Clouds are primary modulators of Earth's energy balance. It is thus important to understand the links connecting variabilities in cloudiness to variabilities in other state variables of the climate system, and also describe how these links would change in a changing climate. A conceptual model of global cloudiness can help elucidate these points. In this work we derive simple representations of cloudiness, that can be useful in creating a theory of global cloudiness. These representations illustrate how both spatial and temporal variability of cloudiness can be expressed in terms of basic state variables. Specifically, cloud albedo is captured by a nonlinear combination of pressure velocity and a measure of the low‐level stability, and cloud longwave effect is captured by surface temperature, pressure velocity, and standard deviation of pressure velocity. We conclude with a short discussion on the usefulness of this work in the context of global warming response studies.
    Description: Plain Language Summary: Clouds are important for Earth's climate, because they affect a large portion of the planet's energy balance, and hence its mean temperature. To better understand how the interplay between cloudiness and energy balance would change in a changing climate, a better theoretical understanding of how clouds are distributed over the planet, and how this connects with the state variables of the climate system such as temperature and wind speed, is required. As theoretical understanding is currently limited, in this work we explore the possibility of very simply representing the spatiotemporal distribution of clouds over the whole planet. We believe that these simple representations advance the field in the direction of a conceptual theory of global cloudiness and its impact on the energy balance. We show that the impact of cloudiness on both solar and terrestrial radiation balance can be captured well globally with only a few predictive fields, like surface temperature or vertical wind speed, combined simply and using only three tunable parameters, and without using any supplementary information such as the particular season or location on the planet.
    Description: Key Points: Model fits are performed to the spatiotemporal observed cloudiness over all oceans, using a minimal set of predictors and parameters. Models capture global‐mean, spatial, and most of seasonal variability of cloud radiative effects. Cloud albedo and longwave effect are captured by pressure velocity and its variance, surface temperature, and lower tropospheric stability.
    Description: CONSTRAIN project EU Horizon 2020
    Keywords: ddc:551.5 ; global cloudiness ; energy balance ; cloud controlling factors
    Language: English
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    FID GEO aktuell: Zweitveröffentlichung von geo­wissenschaftlichen Verlagspublikationen (2021)
    ARGE GMIT, Bonn
    Details
    Publication Date: 2023-12-05
    Description: Dieser Beitrag gibt Hinweise zum Publizieren im Green Open Access und zur Anwendung des Zweitveröffentlichungsrechts.
    Description: DFG, SUB Göttingen
    Description: report
    Keywords: Zweitveröffentlichung ; Zweitveröffentlichungsrecht ; FID GEO
    Language: English
    Type: doc-type:article , publishedVersion
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    On the Temperature Dependence of the Cloud Ice Particle Effective Radius—A Satellite Perspective (2023)
    Details
    Publication Date: 2023-12-05
    Description: Cloud ice particle effective radius in atmospheric models is usually parametrized. A widely‐used parametrization comprises a strong dependence on the temperature. Utilizing available satellite‐based estimates of both cloud ice particle effective radius and cloud‐top temperature we evaluate if a similar temperature‐dependence exists in these observations. We find that for very low cloud‐top temperatures the modeled cloud ice particle effective radius generally agrees on average with satellite observations. For high sub‐zero temperatures however, the modeled cloud ice particle effective radius becomes very large, which is not seen in the satellite observations. We conclude that the investigated parametrization for the cloud ice particle effective radius, and parametrizations with a similar temperature dependence, likely produce systematic biases at the cloud top. Supporting previous studies, our findings suggest that the vertical structure of clouds should be taken into account as factor in potential future updates of the parametrizations for cloud ice particle effective radius.
    Description: Plain Language Summary: Atmospheric models are often used to diagnose and predict the atmospheric state including clouds. One very important property of clouds that consist of ice particles is the cloud ice particle effective radius. This ice effective radius is based on assumptions about the size and shapes of the ice particles in clouds, and thus parametrized, and is one of the important variables needed for calculating the effect of clouds on electromagnetic radiation, in particular on the solar radiation that enters the Earth's atmosphere. In our study we found that the parametrized ice effective radius agrees well on average and global scale with the ice effective radius inferred from satellite observations for cold clouds. However, we also found that for warmer ice clouds the parametrized ice effective radius is much higher than in satellite observations. Our study suggests that parametrizations of the ice effective radius used in atmospheric models show potential for improvements.
    Description: Key Points: Comparisons of modeled cloud ice particle effective radius with satellite observations are presented. For very low cloud temperatures the modeled cloud ice particle effective radius agrees on average with satellite observations. Modeled large cloud ice particle effective radii for high sub‐zero temperatures are not found in satellite observations.
    Description: European Space Agency http://dx.doi.org/10.13039/501100000844
    Description: https://doi.org/10.5281/zenodo.7445152
    Description: https://doi.org/10.5676/DWD/ESA_Cloud_cci/AVHRR-PM/V003
    Description: https://doi.org/10.5676/EUM_SAF_CM/CLARA_AVHRR/V002
    Description: http://doi.org/10.5067/MODIS/MYD06_L2.NRT.061
    Keywords: ddc:551.5 ; clouds ; ice particle effective radius ; parametrization ; model ; satellite observations
    Language: English
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    Understanding Micropolar Theory in the Earth Sciences I: The Eigenfrequency ωr (2021)
    Springer International Publishing
    Details
    Publication Date: 2023-12-05
    Description: Even though micropolar theories are widely applied for engineering applications such as the design of metamaterials, applications in the study of the Earth’s interior still remain limited and in particular in seismology. This is due to the lack of understanding of the required elastic material parameters present in the theory as well as the eigenfrequency ωr which is not observed in seismic data. By showing that the general dynamic equations of the Timoshenko’s beam is a particular case of the micropolar theory we are able to connect micropolar elastic parameters to physically measurable quantities. We then present an alternative micropolar model that, based on the same physical basis as the original model, circumvents the problem of the original eigenfrequency ωr laking in seismological data. We finally validate our model with a seismic experiment and show it is relevant to explain observed seismic dispersion curves.
    Description: Westfälische Wilhelms-Universität Münster (1056)
    Keywords: ddc:551.22 ; Timoshenko beam theory ; plate theory ; Cosserat theory ; micropolar theory ; seismology
    Language: English
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    Deep Learning Based Cloud Cover Parameterization for ICON (2022)
    Details
    Publication Date: 2023-12-05
    Description: A promising approach to improve cloud parameterizations within climate models and thus climate projections is to use deep learning in combination with training data from storm‐resolving model (SRM) simulations. The ICOsahedral Non‐hydrostatic (ICON) modeling framework permits simulations ranging from numerical weather prediction to climate projections, making it an ideal target to develop neural network (NN) based parameterizations for sub‐grid scale processes. Within the ICON framework, we train NN based cloud cover parameterizations with coarse‐grained data based on realistic regional and global ICON SRM simulations. We set up three different types of NNs that differ in the degree of vertical locality they assume for diagnosing cloud cover from coarse‐grained atmospheric state variables. The NNs accurately estimate sub‐grid scale cloud cover from coarse‐grained data that has similar geographical characteristics as their training data. Additionally, globally trained NNs can reproduce sub‐grid scale cloud cover of the regional SRM simulation. Using the game‐theory based interpretability library SHapley Additive exPlanations, we identify an overemphasis on specific humidity and cloud ice as the reason why our column‐based NN cannot perfectly generalize from the global to the regional coarse‐grained SRM data. The interpretability tool also helps visualize similarities and differences in feature importance between regionally and globally trained column‐based NNs, and reveals a local relationship between their cloud cover predictions and the thermodynamic environment. Our results show the potential of deep learning to derive accurate yet interpretable cloud cover parameterizations from global SRMs, and suggest that neighborhood‐based models may be a good compromise between accuracy and generalizability.
    Description: Plain Language Summary: Climate models, such as the ICOsahedral Non‐hydrostatic climate model, operate on low‐resolution grids, making it computationally feasible to use them for climate projections. However, physical processes –especially those associated with clouds– that happen on a sub‐grid scale (inside a grid box) cannot be resolved, yet they are critical for the climate. In this study, we train neural networks that return the cloudy fraction of a grid box knowing only low‐resolution grid‐box averaged variables (such as temperature, pressure, etc.) as the climate model sees them. We find that the neural networks can reproduce the sub‐grid scale cloud fraction on data sets similar to the one they were trained on. The networks trained on global data also prove to be applicable on regional data coming from a model simulation with an entirely different setup. Since neural networks are often described as black boxes that are therefore difficult to trust, we peek inside the black box to reveal what input features the neural networks have learned to focus on and in what respect the networks differ. Overall, the neural networks prove to be accurate methods of reproducing sub‐grid scale cloudiness and could improve climate model projections when implemented in a climate model.
    Description: Key Points: Neural networks can accurately learn sub‐grid scale cloud cover from realistic regional and global storm‐resolving simulations. Three neural network types account for different degrees of vertical locality and differentiate between cloud volume and cloud area fraction. Using a game theory based library we find that the neural networks tend to learn local mappings and are able to explain model errors.
    Description: EC ERC HORIZON EUROPE European Research Council
    Description: Partnership for Advanced Computing in Europe (PRACE)
    Description: NSF Science and Technology Center, Center for Learning the Earth with Artificial Intelligence and Physics (LEAP)
    Description: Deutsches Klimarechenzentrum
    Description: Columbia sub‐award 1
    Description: https://github.com/agrundner24/iconml_clc
    Description: https://doi.org/10.5281/zenodo.5788873
    Description: https://code.mpimet.mpg.de/projects/iconpublic
    Keywords: ddc:551.5 ; cloud cover ; parameterization ; machine learning ; neural network ; explainable AI ; SHAP
    Language: English
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    Impact of Diurnal Warm Layers on Atmospheric Convection (2023)
    Details
    Publication Date: 2023-12-05
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This manuscript presents a study of oceanic diurnal warm layers (DWLs) in kilometer‐scale global coupled simulations and their impact on atmospheric convection in the tropics. With the implementation of thin vertical levels in the ocean, DWLs are directly resolved, and sea surface temperature (SST) fluctuations of up to several Kelvin appear in regions with low wind and high solar radiation. The increase of SST during the day causes an abrupt afternoon increase of atmospheric moisture due to enhanced latent heat flux (LHF), followed by an increase in cloud cover (CC) and cloud liquid water (CLW). However, although the diurnal SST amplitude is even exaggerated in comparison to reanalysis, this effect only lasts for 5–6 hr and leads to an absolute difference of 1% for CC and 0.01 kg m〈sup〉−2〈/sup〉 for CLW. This can be explained by the fact that the low wind over the SST anomalies dampens their potential effect on the LHF and hence clouds. All in all, the impact of DWLs on convective CC is found to be negligible in the tropical mean.〈/p〉
    Description: Plain Language Summary: The diurnal fluctuations of sea surface temperature (SST) have been extensively studied for the last decades, but the assessment of the importance of this phenomenon for atmospheric convection on the global scale has come within reach only very recently, thanks to the development of simulations with a horizontal resolution of O(1 km). In this manuscript we show that we can indeed observe an impact of SST fluctuations on moisture in the atmosphere. However, the impact on the amount of clouds in the tropics is found to be short‐lived and its magnitude negligible on average.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉diurnal warm layers (DWLs) increase atmospheric moisture〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The increase of cloud cover (CC) following the formation of a DWL is immediate and only lasts for several hours〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉The magnitude of the CC increase is small and has no discernible influence on the global mean〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://gotm.net/
    Description: https://hdl.handle.net/21.11116/0000-000C-1447-E
    Keywords: ddc:551 ; diurnal warm layers (DWLs) ; atmospheric moisture ; cloud cover ; convection
    Language: English
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    Transboundary Rainfall Estimation Using Commercial Microwave Links (2023)
    Details
    Publication Date: 2023-12-05
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Unlike actual rainfall, the spatial extent of rainfall maps is often determined by administrative and political boundaries. Similarly, data from commercial microwave links (CMLs) is usually acquired on a national basis and exchange among countries is limited. Up to now, this has prohibited the generation of transboundary CML‐based rainfall maps despite the great extension of networks across the world. We present CML based transboundary rainfall maps for the first time, using independent CML data sets from Germany and the Czech Republic. We show that straightforward algorithms used for quality control strongly reduce anomalies in the results. We find that, after quality control, CML‐based rainfall maps can be generated via joint and consistent processing, and that these maps allow to seamlessly visualize rainfall events traversing the German‐Czech border. This demonstrates that quality control represents a crucial step for large‐scale (e.g., continental) CML‐based rainfall estimation.〈/p〉
    Description: Plain Language Summary: Rainfall maps are usually based on gauge observations on the ground or radar. They are crucial for predicting or reconstructing flooding events. Commercial microwave links are special kinds of rainfall sensors. Their actual purpose is the signal propagation within a cellular network. However, since the signal is attenuated when it rains, they can also be exploited for rainfall estimation. To estimate rainfall from the observed attenuation requires careful data processing. Algorithms for that are usually adjusted to national data sets with their specific characteristics. In this study, we use, for the first time, two independent data sets of commercial microwave links (from Germany and the Czech Republic) with the aim of generating transboundary rainfall maps. As the data sets vary in many respects, several algorithms need to be adjusted and extended to allow processing them consistently. We show that it is possible to create meaningful rainfall maps of rain events that traverse the border between Germany and the Czech Republic. This can be considered a major step toward seamless rainfall maps on even larger, that is, continental scale.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Transboundary rainfall maps based on independent networks of commercial microwave links (CMLs) are generated for the first time〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉German and Czech data sets of CMLs differ significantly with respect to network characteristics〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Quality control is important for heterogeneous data of CMLs〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: German Research Foundation
    Description: Czech Science Foundation
    Description: https://doi.org/10.5281/zenodo.4810169
    Description: https://doi.org/10.5281/zenodo.7973736
    Description: https://opendata.dwd.de/climate_environment/CDC
    Keywords: ddc:551.6 ; transboundary rainfall maps ; commercial microwave links ; quantitative precipitation estimation ; data quality control
    Language: English
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    Missing Rainfall Extremes in Commercial Microwave Link Data Due To Complete Loss of Signal (2023)
    Details
    Publication Date: 2023-12-05
    Description: An important aspect of rainfall estimation is to accurately capture extreme events. Commercial microwave links (CMLs) can complement weather radar and rain gauge data by estimating path‐averaged rainfall intensities near ground. Our aim with this paper was to investigate attenuation induced complete loss of signal (blackout) in the CML data. This effect can occur during heavy rain events and leads to missing extreme values. We analyzed 3 years of attenuation data from 4,000 CMLs in Germany and compared it to a weather radar derived attenuation climatology covering 20 years. We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for longer CMLs (e.g., 〉10 km) despite their increased dynamic range. Therefore, both the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.
    Description: Plain Language Summary: Commercial microwave links (CMLs) are used to transmit information between towers of cellphone networks. If there is rainfall along the transmission path, the signal level is attenuated. By comparing the transmitted and received signal levels, the average rainfall intensity along the path can be estimated. If the attenuation is too strong, no signal is received, no information can be transmitted and no rainfall estimate is available. This is unfavorable both for network stability and rainfall estimation. In this study, we investigated the frequency of such blackouts in Germany. How many blackouts per year are observed in a 3 year CML data set covering around 4,000 link paths and how many are expected from 20 years of weather radar data? We observed that the average CML experiences 8.5 times more blackouts than we would have expected from the radar derived climatology. Blackouts did occur more often for long CMLs, which was an unexpected finding. While only one percent of the annual rainfall amount is missed during blackouts, the probability that a blackout occurs was very high for high rain rates. Both, the hydrometeorological community and network providers can consider our analysis to develop mitigation measures.
    Description: Key Points: Complete loss of commercial microwave link (CML) signals during heavy rain leads to missing rainfall extremes. Magnitude of observed blackouts exceeds climatologically expected values. Unexpectedly, longer CMLs experience more blackouts.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Karlsruhe Institute of Technology http://dx.doi.org/10.13039/100009133
    Description: https://doi.org/10.5281/zenodo.7245440
    Description: https://github.com/pycomlink/pycomlink/blob/12fc302539851b19f7656cf7e2438c0ddbaa48bf/notebooks/Blackout%20gap%20detection%20examples.ipynb
    Description: https://doi.org/10.5281/zenodo.6337557
    Description: https://doi.org/10.5676/DWD/RADKLIM_YW_V2017.002
    Keywords: ddc:551.6 ; commercial microwave links ; rainfall ; opportunistic sensing ; weather radar ; rainfall extremes ; precipitation
    Language: English
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    Impact of Cyclonic Wind Anomalies Caused by Massive Winter Sea Ice Retreat in the Barents Sea on Atlantic Water Transport Toward the Arctic: A Model Study (2023)
    Details
    Publication Date: 2023-12-05
    Description: The Arctic is warming much faster than the global average. This is known as Arctic Amplification and is caused by feedbacks in the local climate system. In this study, we explore a previously proposed hypothesis that an associated wind feedback in the Barents Sea could play an important role by increasing the warm water inflow into the Barents Sea. We find that the strong recent decrease in Barents Sea winter sea ice cover causes enhanced ocean‐atmosphere heat flux and a local air temperature increase, thus a reduction in sea level pressure and a local cyclonic wind anomaly with eastward winds in the Barents Sea Opening. By investigating various reanalysis products and performing high‐resolution perturbation experiments with the ocean and sea ice model FESOM2.1, we studied the impact of cyclonic atmospheric circulation changes on the warm Atlantic Water import into the Arctic via the Barents Sea and Fram Strait. We found that the observed wind changes do not significantly affect the warm water transport into the Barents Sea, which rejects the wind‐feedback hypothesis. At the same time, the cyclonic wind anomalies in the Barents Sea increase the amount of Atlantic Water recirculating westwards in Fram Strait by a downslope shift of the West Spitsbergen Current, and thus reduce Atlantic Water reaching the Arctic basin via Fram Strait. The resulting warm‐water anomaly in the Greenland Sea Gyre drives a local anticyclonic circulation anomaly.
    Description: Plain Language Summary: The Barents Sea has been experiencing a rapid decrease in its winter sea ice extent during the last 30 years. The loss of sea ice creates new areas where, in winter, the relatively warm ocean loses heat to the cold atmosphere. As warm air rises, the warming reduces the sea level air pressure, changing the atmospheric circulation to develop a local anticlockwise wind system centered over the northern Barents Sea. The associated eastward winds in the Barents Sea Opening and southeastward winds in Fram Strait affect how warm water from the North Atlantic moves toward the Arctic. There has been a long debate on whether this wind anomaly can increase the warm Atlantic Water transport into the Barents Sea and thus cause a positive feedback mechanism for further reducing the sea ice through melting. We find that the observed atmospheric circulation changes have no significant impact on the Barents Sea warm water inflow and thus reject the wind feedback as a strong player in contributing to Arctic Amplification. However, strong anomalous southeastward winds in Fram Strait and the northern Nordic Seas cause a southward shift of the warm Atlantic Water recirculation and reduce its flow toward the Arctic.
    Description: Key Points: A hypothesis that a wind feedback contributes to Arctic Amplification is rejected by performing dedicated wind perturbation simulations. Winter sea ice retreat in the northern Barents Sea causes anomalous cyclonic winds by locally enhancing ocean heat loss. Anomalous cyclonic winds result in less Atlantic Water transport through Fram Strait.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: North‐German Supercomputing Alliance
    Description: https://github.com/FESOM/fesom2
    Description: https://doi.org/10.7265/N5K072F8
    Description: https://doi.org/10.5065/D6HH6H41
    Description: https://doi.org/10.5065/D6WH2N0S
    Description: https://github.com/FESOM/pyfesom2
    Description: https://doi.org/10.5281/zenodo.7458143
    Keywords: ddc:551 ; Barents Sea ; Arctic Amplification ; feedback ; Atlantic water ; modeling ; Fram Strait
    Language: English
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    Tetrapodenfährten aus dem saarpfälzischen Rotliegenden (? Ober-Karbon - Unter-Perm; Südwest-Deutschland) (1983)
    Details
    Publication Date: 2023-12-05
    Description: Es werden Morphologie, Proportionen und Belastungsverhältnisse der Fährtentaxa Saurichnites salamandroides Geinitz, 1861, Saurichnites incurvatus Fritsch, 1901, Saurichnites intermedius Fritsch, 1895, Limnopus palatinus nov. ichnospec., Amphisauroides sp., Protritonichnites lacertoides (Geinitz, 1861), Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882), Gilmoreichnus minimus Haubold, 1973, Hyloidichnus arnhardti Haubold, 1973 und Jacobiichnus caudifer (Fritsch, 1895) beschrieben. Außerdem werden die Körperproportionen der fährtenerzeugenden Tiere in hypothetischer Form rekonstruiert und ihre orthotaxonomische Position diskutiert.
    Description: Abstract: Morphology, proportions and pressure distribution of the ichnotaxa Saurichnites salamandroides Geinitz, 1861, Saurichnites incurvatus Fritsch, 1901, Saurichnites intermedius Fritsch, 1895, Limnopus palatinus nov. ichnospec., Amphisauroides sp., Protritonichnites lacertoides (Geinitz, 1861), Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882), Gilmoreichnus minimus Haubold, 1973, Hyloidichnus arnhardti Haubold, 1973 and Jacobiichnus caudifer (Fritsch, 1895) are described. In addition to this the body-proportions of the trackway-producing animals are reconstructed hypothetically. The orthotaxonomic position of these animals is discussed.
    Description: 1. Einleitung 2. Fundorte und Fundschichten 3. Terminologie der Fährten. 4. Beschreibung der Fährten 4.1. Saurichnites salamandroides Gbinitz, 1861 4.2. Saurichnites incurvatus Fritsch, 1901 4.3. Saurichnites intermedius Fritsch, 1895 4.4. Limnopus palatinus nov. ichnospec. 4.5. Amphisauroides sp. 4.6. Protritonichnites lacertoides (Geinitz, 1861) 4.7. Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882) 4.8. Gilmoreichnus minimus Haubö'lt), 1973 4.9. Hyloidichnus arnhardti Haubold, 1973 4.10. Jacobiichnus caudifer (Fritsch, 1895) 5. Schlußbemerkungen Schriften
    Description: research
    Keywords: ddc:562 ; Saar-Nahe-Becken ; Tetrapoden ; Rotliegend
    Language: German
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    Tetrapodenfährten aus dem Oberkarbon (Westfalium A und C) West- und Südwestdeutschlands (1982)
    Details
    Publication Date: 2023-12-05
    Description: Es werden die Fährtentaxa Cincosaurus tauentzieni nov. ichnospec., Cursipes weingardti nov. ichnospec., cf. Limnopus littoralis, Pseudobradypus erini, Anomoeichnus ohioensis und Schmidtopus praesidentis beschrieben. Palaeosauropus (Asperipes) sp. wird als morphologische Variante von Pseudobradypus erini vermutet. Daneben werden die Körperproportionen der Fährtenerzeuger hypothetisch rekonstruiert und ihre Stellung innerhalb des orthotaxonomischen Systems erörtert.
    Description: Abstract: The ichno-taxa Cincosaurus tauentzieni nov. ichnospec., Cursipes weingardti nov. ichnospec., cf. Limnopus littoralis, Pseudobradypus erini, Anomoeichnus ohioensis and Schmidtopus praesidentis are described. Palaeosauropus (Asperipes) sp. is supposed to be a morphological variant of Pseudobradypus erini. In addition to this the body proportions of the producing animals are reconstructed hypothetically. The orthotaxonomic position of these animals is discussed.
    Description: 1. Einleitung 2. Fundort und Fundschichten 2.1. Saarkarbon (Westfalium C) 2.2. Ruhrkarbon (Westfalium A) 3. Terminologie 4. Beschreibung der Fährten 4.1. Cincosaurus tauentzieni nov. ichnospec. 4.2. Cursipes weingardti nov. ichnospec. 4.3. cf. Limnopus littoralis (Marsh, 1894) 4.4. Pseudobradypus erini (Schmidt, 1963) 4.5. Anomoeichnus ohioensis Carman, 1927 4.6. Schmidtopus praesidentis (Schmidt, 1956) 8 4.7. Kritische Bemerkungen zu Palaeosauropus (Asperipes) sp. 4.8. Ichnia indet. 5. Schlußbemerkungen Schriften
    Description: research
    Keywords: ddc:562 ; Oberkarbon ; Saarland ; Tetrapoden
    Language: German
    Type: doc-type:article , publishedVersion
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  • 56
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    Quantitative 3D imaging of partially saturated granular materials under uniaxial compression (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-12-04
    Description: Gauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: LabEx Tec 21 (Investissements d’Avenir)
    Description: Technische Universität Hamburg (3140)
    Keywords: Partially saturated granular soils ; Shear strength ; Uniaxial compression tests ; X-ray computed tomography
    Language: English
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  • 57
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    Using diffraction losses of X‐rays in a single crystal for determination of its lattice parameters as well as for monochromator calibration (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-12-04
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉A way has been developed to measure the unit‐cell parameters of a single crystal just from an energy scan with X‐rays, even when the exact energy of the X‐rays is not well defined due to an error in the pitch angle of the monochromator. The precision of this measurement reaches 〈italic〉da〈/italic〉/〈italic〉a〈/italic〉 ∼ 1 × 10〈sup〉−5〈/sup〉. The method is based on the analysis of diffraction losses of the beam, transmitted through a single crystal (the so‐called `glitch effect'). This method can be easily applied to any transmissive X‐ray optical element made of single crystals (for example, X‐ray lenses). The only requirements are the possibility to change the energy of the generated X‐ray beam and some intensity monitor to measure the transmitted intensity. The method is agnostic to the error in the monochromator tuning and it can even be used for determination of the absolute pitch (or 2gθ) angle of the monochromator. Applying the same method to a crystal with well known lattice parameters allows determination of the exact cell parameters of the monochromator at any energy.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Diffraction losses (glitches) at certain energies of the X‐ray beam, transmitted through a single crystal, can be used for lattice parameters determination as well as for calibrating the monochromator (absolute pitch angle and the unit‐cell parameter).〈boxed-text position="anchor" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:16005775:jsy2ay5590:jsy2ay5590-fig-0001"〉 〈alt-text〉image〈/alt-text〉 〈/graphic〉〈/boxed-text〉〈/p〉
    Keywords: ddc:548 ; X‐ray glitches ; diffraction losses ; unit‐cell parameter ; single‐crystal X‐ray optics ; monochromator calibration
    Language: English
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  • 58
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    The geodynamic and limnological evolution of Balkan Lake Ohrid, possibly the oldest extant lake in Europe (2022)
    Details
    Publication Date: 2023-12-04
    Description: Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584‐m‐long DEEP sediment succession and a comparison to a 197‐m‐long sediment succession from the Pestani site ~5 km to the east in the lake, where drilling ended close to the bedrock, to unravel the earliest history of Lake Ohrid and its basin development. 26Al/10Be dating of clasts from the base of the DEEP sediment succession implies that the sedimentation in the modern basin started at c. 2 Ma. Geophysical, sedimentological and micropalaeontological data allow for chronological information to be transposed from the DEEP to the Pestani succession. Fluvial conditions, slack water conditions, peat formation and/or complete desiccation prevailed at the DEEP and Pestani sites until 1.36 and 1.21 Ma, respectively, before a larger lake extended over both sites. Activation of karst aquifers to the east probably by tectonic activity and a potential existence of neighbouring Lake Prespa supported filling of Lake Ohrid. The lake deepened gradually, with a relatively constant vertical displacement rate of ~0.2 mm a−1 between the central and the eastern lateral basin and with greater water depth presumably during interglacial periods. Although the dynamic environment characterized by local processes and the fragmentary chronology of the basal sediment successions from both sites hamper palaeoclimatic significance prior to the existence of a larger lake, the new data provide an unprecedented and detailed picture of the geodynamic evolution of the basin and lake that is Europe’s presumed oldest extant freshwater lake.
    Keywords: ddc:551 ; Balkan Peninsula ; Lake Ohrid ; DEEP sediment succession ; Pestani succession ; evolutionary dynamics ; regional climate history
    Language: English
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  • 59
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    Central Mediterranean tephrochronology between 313 and 366 ka: New insights from the Fucino palaeolake sediment succession (2022)
    Leicher, Niklas ; Giaccio, Biagio ; Pereira, Alison ; [et al.]
    Details
    Publication Date: 2023-12-04
    Description: Thirty‐two tephra layers were identified in the time‐interval 313–366 ka (Marine Isotope Stages 9–10) of the Quaternary lacustrine succession of the Fucino Basin, central Italy. Twenty‐seven of these tephra layers yielded suitable geochemical material to explore their volcanic origins. Investigations also included the acquisition of geochemical data of some relevant, chronologically compatible proximal units from Italian volcanoes. The record contains tephra from some well‐known eruptions and eruptive sequences of Roman and Roccamonfina volcanoes, such as the Magliano Romano Plinian Fall, the Orvieto–Bagnoregio Ignimbrite, the Lower White Trachytic Tuff and the Brown Leucitic Tuff. In addition, the record documents eruptions currently undescribed in proximal (i.e. near‐vent) sections, suggesting a more complex history of the major eruptions of the Colli Albani, Sabatini, Vulsini and Roccamonfina volcanoes between 313 and 366 ka. Six of the investigated tephra layers were directly dated by single‐crystal‐fusion 40Ar/39Ar dating, providing the basis for a Bayesian age–depth model and a reassessment of the chronologies for both already known and dated eruptive units and for so far undated eruptions. The results provide a significant contribution for improving knowledge on the peri‐Tyrrhenian explosive activity as well as for extending the Mediterranean tephrostratigraphical framework, which was previously based on limited proximal and distal archives for that time interval.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Italian Ministry of Education, University and Research
    Description: https://doi.org/10.26022/IEDA/112322
    Keywords: ddc:552.2 ; Fucino Basin ; palaeolake sediment succession ; tephra
    Language: English
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  • 60
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    Experimental Evidence for Shear‐Induced Melting and Generation of Stishovite in Granite at Low (〈18 GPa) Shock Pressure (2023)
    Details
    Publication Date: 2023-12-04
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Knowledge of the shock behavior of planetary materials is essential to interpret shock metamorphism documented in rocks at hypervelocity impact structures on Earth, in meteorites, and in samples retrieved in space missions. Although our understanding of shock metamorphism has improved considerably within the last decades, the effects of friction and plastic deformation on shock metamorphism of complex, polycrystalline, non‐porous rocks are poorly constrained. Here, we report on shock‐recovery experiments in which natural granite was dynamically compressed to 0.5–18 GPa by singular, hemispherically decaying shock fronts. We then combine petrographic observations of shocked samples that retained their pre‐impact stratigraphy with distributions of peak pressures, temperatures, and volumetric strain rates obtained from numerical modeling to systematically investigate progressive shock metamorphism of granite. We find that the progressive shock metamorphism of granite observed here is mainly consistent with current classification schemes. However, we also find that intense shear deformation during shock compression and release causes the formation of highly localized melt veins at peak pressures as low as 6 GPa, which is an order of magnitude lower than currently thought. We also find that melt veins formed in quartz grains compressed to >10–12 GPa contain the high‐pressure silica polymorph stishovite. Our results illustrate the significance of shear and plastic deformation during hypervelocity impact and bear on our understanding of how melt veins containing high‐pressure polymorphs form in moderately shocked terrestrial impactites or meteorites.〈/p〉
    Description: Plain Language Summary: When asteroids, comets, or smaller fragments thereof impact the solid surfaces of planets, moons, or other asteroids, the rocks they strike undergo sudden and irreversible changes while an impact crater forms. These material changes are called shock metamorphism and result from the extremely high pressures, temperatures, and deformation rates caused by the impact. However, the role of rapid shear deformation on impact heating and shock metamorphism is poorly understood. Using a novel experimental setup, we performed shock‐wave experiments with granite, a naturally occurring rock, that allows us to study the role of extreme deformation rates during impact‐crater formation. Furthermore, our experimental setup allows us to avoid several pitfalls such as excavation and ejection of shocked material from a growing impact crater or multiple reflections of shock waves at sample containers that typically plagued previous experiments. We find that intense shear deformation during crater formation results in significant but highly localized heating. This additional heating causes melting of granite at shock pressures as low as 6 GPa, which is about 10 times less than currently thought. Our findings may explain how thin melt veins often observed in shock‐metamorphosed meteorites or rocks sampled from terrestrial impact craters have formed.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉We performed shock recovery experiments with granite and spherically decaying compressive waves; numerical models constrain peak pressures〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Shocked granite samples are found to retain pre‐impact stratigraphy and to document shock‐stage transitions between 〈0.5 and ∼18 GPa〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Shear‐induced melting of granite at bulk peak pressures as low as 6 GPa; stishovite nucleated as a liquidus phase in melt veins at >10 GPa〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Japan Society for the Promotion of Science
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:https://isale-code.github.io/terms-of-use.html ; ddc:https://doi.org/10.5281/zenodo.7881492 ; ddc:552 ; shock metamorphism ; granite ; stishovite ; melt vein ; shock recovery ; numerical modeling
    Language: English
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  • 61
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    Anorthositic lunar regolith breccia Dhofar 1769—Clear indications for repeated mixing of impact melt lithologies (2023)
    Details
    Publication Date: 2023-12-04
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The lunar regolith breccia Dhofar 1769, which was found in 2012 as a single 125 g piece in the Zufar desert area of Oman, contains a relatively large, dark‐colored impact melt breccia embedded in a fine‐grained clastic matrix. The internal texture of the fragment indicates the repeated melt breccia formation on the lunar surface, their repeated brecciation, and mixing in second, third, and fourth generations of brecciated rock types. The chemical and mineralogical data reveal the incorporation of a feldspar‐rich subophitic crystalline melt within a feldspar‐rich microporphyritic crystalline melt breccia. This lithic paragenesis itself is embedded within a mafic, crystalline melt breccia. The entire breccia with the three different impact melts has been finally incorporated into the whole rock breccia. The three impact melts are mixtures of different source rocks and impact projectiles, based on the obtained minor and trace element compositions (in particular of Ni and the rare earth elements [REE]) of the impact melt lithologies. For all processes of impact melt formation, additional steps of their brecciation and re‐lithification require a minimum number of seven impact processes.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:552 ; Dhofar 1769 ; lunar regolith breccia ; impact melt formation ; brecciation ; re-lithification ; impact processes
    Language: English
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  • 62
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    Young magmatism and Si‐rich melts on Mars as documented in the enriched gabbroic shergottite NWA 6963 (2022)
    Details
    Publication Date: 2023-11-28
    Description: Enriched shergottites contain interstitial Si‐rich mesostasis; however, it is unclear whether such mesostasis is formed by impact or magmatic processes. We use laser ablation multicollector inductively coupled plasma mass spectrometry U–Pb measurements of minerals within the interstitial Si‐rich mesostasis and of merrillite within the coarse‐grained groundmass of Martian‐enriched gabbroic shergottite Northwest Africa (NWA) 6963. The date derived of tranquillityite, Cl‐apatite, baddeleyite, and feldspar from the Si‐rich mesostasis is 172.4 ± 6.1 Ma, and the derived merrillite date is 178.3 ± 10.6 Ma. We conclude, based on textural observation, that merrillite is a late magmatic phase in NWA 6963, that it was not produced by shock, and that its U–Pb‐system was not reset by shock. The indistinguishable dates of the gabbroic merrillite and the minerals within the Si‐rich mesostasis in NWA 6963 indicate that the Si‐rich mesostasis represents a late‐stage differentiated melt produced in the final phase of the magmatic history of the gabbroic rock and not a shock melt. This can likely be transferred to similar Si‐rich mesostases in other enriched shergottites and opens the possibility for investigations of Si‐rich mesostasis in enriched shergottites to access their magmatic evolution. Our results also provide a crystallization age of 174 ± 6 Ma (weighted average) for NWA 6963.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Dr. Rolf M. Schwiete Stiftung http://dx.doi.org/10.13039/501100020027
    Keywords: ddc:552 ; Mars ; shergottites ; mesostasis
    Language: English
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  • 63
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    Bioavailable DOC: reactive nutrient ratios control heterotrophic nutrient assimilation—An experimental proof of the macronutrient-access hypothesis (2021)
    Graeber, Daniel ; Tenzin, Youngdoung ; Stutter, Marc ; [et al.]
    Springer International Publishing
    Details
    Publication Date: 2023-11-28
    Description: We investigate the "macronutrient-access hypothesis", which states that the balance between stoichiometric macronutrient demand and accessible macronutrients controls nutrient assimilation by aquatic heterotrophs. Within this hypothesis, we consider bioavailable dissolved organic carbon (bDOC), reactive nitrogen (N) and reactive phosphorus (P) to be the macronutrients accessible to heterotrophic assimilation. Here, reactive N and P are the sums of dissolved inorganic N (nitrate-N, nitrite-N, ammonium-N), soluble-reactive P (SRP), and bioavailable dissolved organic N (bDON) and P (bDOP). Previous data from various freshwaters suggests this hypothesis, yet clear experimental support is missing. We assessed this hypothesis in a proof-of-concept experiment for waters from four small agricultural streams. We used seven different bDOC:reactive N and bDOC:reactive P ratios, induced by seven levels of alder leaf leachate addition. With these treatments and a stream-water specific bacterial inoculum, we conducted a 3-day experiment with three independent replicates per combination of stream water, treatment, and sampling occasion. Here, we extracted dissolved organic matter (DOM) fluorophores by measuring excitation-emission matrices with subsequent parallel factor decomposition (EEM-PARAFAC). We assessed the true bioavailability of DOC, DON, and the DOM fluorophores as the concentration difference between the beginning and end of each experiment. Subsequently, we calculated the bDOC and bDON concentrations based on the bioavailable EEM-PARAFAC fluorophores, and compared the calculated bDOC and bDON concentrations to their true bioavailability. Due to very low DOP concentrations, the DOP determination uncertainty was high, and we assumed DOP to be a negligible part of the reactive P. For bDOC and bDON, the true bioavailability measurements agreed with the same fractions calculated indirectly from bioavailable EEM-PARAFAC fluorophores (bDOC r〈sup〉2〈/sup〉 = 0.96, p 〈 0.001; bDON r〈sup〉2〈/sup〉 = 0.77, p 〈 0.001). Hence we could predict bDOC and bDON concentrations based on the EEM-PARAFAC fluorophores. The ratios of bDOC:reactive N (sum of bDON and DIN) and bDOC:reactive P (equal to SRP) exerted a strong, predictable stoichiometric control on reactive N and P uptake (R〈sup〉2〈/sup〉 = 0.80 and 0.83). To define zones of C:N:P (co-)limitation of heterotrophic assimilation, we used a novel ternary-plot approach combining our data with literature data on C:N:P ranges of bacterial biomass. Here, we found a zone of maximum reactive N uptake (C:N:P approx. 〉 114: 〈 9:1), reactive P uptake (C:N:P approx. 〉 170:21: 〈 1) and reactive N and P co-limitation of nutrient uptake (C:N:P approx. 〉 204:14:1). The “macronutrient-access hypothesis” links ecological stoichiometry and biogeochemistry, and may be of importance for nutrient uptake in many freshwater ecosystems. However, this experiment is only a starting point and this hypothesis needs to be corroborated by further experiments for more sites, by in-situ studies, and with different DOC sources.
    Description: Rural and Environment Science and Analytical Services Division http://dx.doi.org/10.13039/100011310
    Description: Helmholtz-Gemeinschaft http://dx.doi.org/10.13039/501100001656
    Description: Helmholtz-Zentrum für Umweltforschung GmbH - UFZ (4215)
    Keywords: ddc:551.9 ; Ecological stoichiometry ; Dissolved organic nitrogen ; PARAFAC ; Dissolved inorganic nitrogen ; Phosphate ; Ternary plots
    Language: English
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  • 64
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    Observations of Gravity Wave Refraction and Its Causes and Consequences (2023)
    Details
    Publication Date: 2023-11-28
    Description: Horizontal gravity wave (GW) refraction was observed around the Andes and Drake Passage during the SouthTRAC campaign. GWs interact with the background wind through refraction and dissipation. This interaction helps to drive midatmospheric circulations and slows down the polar vortex by taking GW momentum flux (GWMF) from one location to another. The SouthTRAC campaign was composed to gain improved understanding of the propagation and dissipation of GWs. This study uses observational data from this campaign collected by the German High Altitude Long Range research aircraft on 12 September 2019. During the campaign a minor sudden stratospheric warming in the southern hemisphere occurred, which heavily influenced GW propagation and refraction and thus also the location and amount of GWMF deposition. Observations include measurements from below the aircraft by Gimballed Limb Observer for Radiance Imaging of the Atmosphere and above the aircraft by Airborne Lidar for the Middle Atmosphere. Refraction is identified in two different GW packets as low as ≈4 km and as high as 58 km. One GW packet of orographic origin and one of nonorographic origin is used to investigate refraction. Observations are supplemented by the Gravity‐wave Regional Or Global Ray Tracer, a simplified mountain wave model, ERA5 data and high‐resolution (3 km) WRF data. Contrary to some previous studies we find that refraction makes a noteworthy contribution in the amount and the location of GWMF deposition. This case study highlights the importance of refraction and provides compelling arguments that models should account for this.
    Description: Plain Language Summary: Gravity waves (GWs) are very important for models to reproduce a midatmospheric circulations. But the fact is that models oversimplify the GW physics which results in GWs being underrepresented in models. GW refraction is one of the processes not captured by the physics in model parameterization schemes. This article uses high‐resolution observations from the SouthTRAC campaign to show how GWs refract and highlight the importance there‐of. This case study shows a 25% increase in the GWMF during propagation. The increase in momentum flux is linked to refraction which results in a shortening in the GW horizontal wavelength. This article shows that refraction is important for the amount as well as the location of GWMF deposition. This case study highlights the importance of refraction and provides compelling arguments that models should account for this.
    Description: Key Points: A case study reveals that refraction results in a 25% increase in gravity wave momentum flux (GWMF). Including refraction dynamics affects the location of GWMF deposition. Refraction is prominent in strong wind gradients (i.e., displaced vortex conditions).
    Description: ANPCYT PICT
    Description: DFG
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Instituto de Física de Buenos Aires
    Description: SNCAD MinCyT initiative
    Description: HALO‐SPP
    Description: ROMIC WASCLIM
    Description: https://doi.org/10.5281/zenodo.6997443
    Description: https://cds.climate.copernicus.eu/cdsapp%23%21/home
    Keywords: ddc:551.5 ; gravity wave ; mountain wave ; refraction ; Andes ; Drake Passage ; gravity wave momentum flux
    Language: English
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  • 65
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    Trilobitenfunde am Lagergang vom Wasenbachtal (südwestliche Lahnmulde) (2023)
    Details
    Publication Date: 2023-11-28
    Description: In einem längst stillgelegten Steinbruch im Wasenbachtal in der südwestlichen Lahnmulde (Rheinisches Schiefergebirge) haben die Übergangsschichten vom Unter- zum Mitteldevon in den Kontaktflächen eines Lagerganges reichhaltige Fossilfunde ermöglicht. Dies betrifft vor allem die Fossilgruppe der Trilobiten, wobei der Steinbruch im Wasenbachtal eine reiche Fauna geliefert hat. Die Fundmöglichkeiten haben sich mittlerweile weitgehend verschlechtert. Neufunde wurden aus dem Nordbruch durch Flick & Flick (2022) beschrieben. Hierzu ergänzend werden die zwei Vertreter der Otarioninae Richter & Richter, 1926 Cyphaspis? moei n. sp. und Otarion hetairos n. sp. beschrieben.
    Description: Abstract: The fossils described here were found in an abandoned quarry in the Wasenbach Valley in the southwestern Lahn syncline (Rhenish Massif, western Germany) in a host rock being stratigraphically transitional from the Lower to the Middle Devonian and exposed in contact with a volcanic sill. The quarry is known to host quite a variety of fossils of which trilobites have earned the greatest interest. Unfortunately, in the course of time collecting possibilities have significantly declined and new findings are scarce. Nevertheless, new species could be established by Flick & Flick (2022) from material collected from the hanging wall of the sill in the northern part of the quarry. Two more new species, Cyphaspis? moei n. sp. and Otarion hetairos n. sp., both belonging to the subfamily Otarioninae (Richter & Richter, 1926), are described here.
    Description: research
    Keywords: ddc:562 ; Rheinisches Schiefergebirge ; Lahnmulde ; Unterdevon ; Mitteldevon ; Trilobiten
    Language: German
    Type: doc-type:article
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  • 66
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    Untermiozäne Fossilgemeinschaften der Wiesbaden-Formation aus einem Tertiärprofil in Mainz (Mainz-Gruppe, Mainzer Becken, Deutschland) (2023)
    Details
    Publication Date: 2023-11-28
    Description: Die Mollusken aus dem Aufschluss Baugrube Weisenauer Straße 5 in Mainz (Wiesbaden-Formation, Aquitanium) werden dokumentiert. Es wurden 10 Arten euryöker Süß- und Brackwasserbewohner und bis zu 13 Arten von Landschnecken nachgewiesen, wovon fünf nur in unbestimmbaren Fragmenten vorlagen. Neunachweise für die Wiesbaden- Formation sind die aquatische Art Schuettemmericia sp. und Pupisoma (Ptychopatula) schaeferi n.sp., Metachloraea sp. und Oxychilidae sp. bei den Landschnecken. Für Hydrobia? tenuimarginata (Ludwig 1865) wird ein Neotypus festgelegt. Neue Synonyme: Hydrobia obtusa subdistorta Wenz 1930 ist synonym mit Hydrobia? tenuimarginata, Mytulites neritoideus Schlotheim 1820 mit Dreissena (Coelogonia) brardii (Brongniart 1823) und Leucochroa (Leucochroopsis) emmerichi Boettger 1908 mit Leucochroopsis crebripunctata (Sandberger 1858). Prioritätsumkehr wird zwischen Mytulites neritoideus Schlotheim 1820 und Mytilus brardii Brongniart 1823 nach Artikel 23.9 (International Commission on Zoological Nomenclature 1999) festgelegt.
    Description: Abstract: The mollusks from an outcrop in the excavation Weisenauer Straße 5 in Mainz (Wiesbaden- Formation, Aquitanian) are documented. 10 species of euryoecious fresh and brackish water inhabitants and up to 13 species of land snails, of which 5 were only present as indeterminable fragments, are recorded. New records for the Wiesbaden-Formation are the aquatic species Schuettemmericia sp. and Pupisoma (Ptychopatula) schaeferi n.sp., Metachloraea sp., and Oxychilidae sp. in the land snails. A neotype is designated for Hydrobia? tenuimarginata (Ludwig 1865). New synonyms: Hydrobia obtusa subdistorta Wenz 1930 is synonymous with Hydrobia? tenuimarginata, Mytulites neritoideus Schlotheim 1820 is synonymous with Dreissena (Coelogonia) brardii (Brongniart 1823) and Leucochroa (Leucochroopsis) emmerichi O. Boettger 1908 is synonymous with Leucochroopsis crebripunctata (Sandberger 1858). Reversal of precendence according to article 23.9 (International Commission on Zoological Nomenclature 1999) is established between Mytulites neritoideus Schlotheim 1820 and Mytilus brardii Brongniart 1823.
    Description: research
    Keywords: ddc:562 ; Mainzer Becken ; Wiesbaden-Formation ; Miozän ; Mollusken ; TK 6015
    Language: German
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    Untermiozäne Fossilgemeinschaften der Wiesbaden-Formation aus einem Tertiärprofil in Mainz (Mainz-Gruppe, Mainzer Becken, Deutschland) (2023)
    Details
    Publication Date: 2023-11-28
    Description: Aus der Schicht 3b des Profils Weisenauer Straße 5 (Schäfer et al. 2023) konnten sieben Säugetier-Taxa nachgewiesen werden. Diese sind den Ordnungen Lipotyphla (Insectivora), Rodentia und Lagomorpha zuzuordnen. Das gemeinsame Vorkommen des Eomyiden Pseudotheridomys aff. lacombai Alvarez Sierra 1987 und der hasenartigen Art Titanomys visenoviensis (von Meyer 1843) lässt eine biostratigraphische Zuordnung der untersuchten Schicht zum Kleinsäugerniveau MN 2a (Niveau von La Chaux) oder MN 2b (Niveau von Vully) annehmen.
    Description: Abstract: From layer 3b of the Weisenauer Straße 5 profile (Schäfer et al. 2023), seven mammalian taxa could be detected. These can be assigned to the orders Lipotyphla (Insectivora), Rodentia and Lagomorpha. The common occurrence of the Eomyid Pseudotheridomys aff. lacombai Alvarez Sierra 1987 and the hare-like species Titanomys visenoviensis (von Meyer 1843) suggests a biostratigraphic assignment of the examined layer to the small mammal level MN 2a (level of La Chaux) or MN 2b (level of Vully).
    Description: Résumé: A partir de la couche 3b du profil Weisenauer Straße 5 (Schäfer et al. 2023), sept taxons de mammifères ont pu être identifiés. Ceux-ci peuvent être attribués aux ordres Lipotyphla (Insectivora), Rodentia et Lagomorpha. La présence commune de l'Eomyid Pseudotheridomys aff. lacombai Alvarez Sierra 1987 et l'espèce lièvre Titanomys visenoviensis (von Meyer 1843) suggère l'attribution biostratigraphique de la couche examinée au niveau des petits mammifères MN 2a (niveau de La Chaux) ou MN 2b (niveau du Vully).
    Description: research
    Keywords: ddc:562 ; Mainzer Becken ; Wiesbaden-Formation ; Miozän ; Säuger ; TK 6015
    Language: German
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    Devononeseuretus beichti n. gen., n. sp., der Erstnachweis eines Calymeniden (Trilobita) aus dem Hunsrückschiefer (2023)
    Details
    Publication Date: 2023-11-28
    Description: Aus dem Hunsrückschiefer von Bundenbach wird der Trilobit Devononeseuretus beichti n. gen, n. sp. beschrieben. Devononeseuretus n. gen. ist die erste bekannte Gattung der Calymenidae Milne Edwards, 1840 aus dem Hunsrückschiefer. Als Vertreter der Reedocalymeninae Hupé, 1955 verlängert ihr Nachweis die stratigrafische Reichweite ihrer Unter-Familie vom frühen Ordovizium bis ins frühe Unter-Emsium des Unterdevons. Unklar bleibt, warum das Taxon als seinerzeit „Lebendes Fossil“ noch im Lebensraum des Hunsrückschiefers existieren konnte.
    Description: Abstract: The trilobite Devononeseuretus beichti n. gen, n. sp. is described from the Hunsrück Slate of Bundenbach. Devononeseuretus n. gen. is the first known genus of the Calymenidae Milne Edwards, 1840 from the Hunsrück Slate. As a representative of the Reedocalymeninae Hupé, 1955 it extends the stratigraphic range of its subfamily from the early Ordovician to the early Lower Emsian of the Lower Devonian. It remains unclear why this taxon could still exist as a contemporary “living fossil” in the environment of the Hunsrück Slate.
    Description: research
    Keywords: ddc:562 ; Rheinisches Schiefergebirge ; Unterdevon ; Trilobiten
    Language: German
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    Erstnachweis von Devonaster Schuchert, 1914 im deutschen Unter-Devon (Asteroidea, Echinodermata) (2023)
    Details
    Publication Date: 2023-11-28
    Description: In diesem Beitrag wird Devonaster Schuchert, 1914 erstmals für Deutschland nachgewiesen. Die zu den Xenasteridae Gregory, 1899 gestellte Gattung war bisher nur aus dem Mittel-Devon von Nord-Amerika (New York, Ontario) bekannt. Die Neufunde stammen aus neritischen Ablagerungen des Unter-Emsium (Rheinische Fazies) im Westerwald (Rheinland- Pfalz) und sind somit deutlich älter. Die verhältnismäßig vollständig artikulierten Exemplare werden hier als Devonaster wenndorfi n. sp. und Devonaster daadenensis n. sp. vorgestellt. Sie zeigen enge Beziehungen zur Typusart Devonaster eucharis (Hall, 1868) aus dem Mittel-Devon von New York. Differenzen zu den ebenfalls im deutschen Unter-Devon vorkommenden Gattungen Xenaster Simonowitsch, 1871 und Spaniaster Schöndorf, 1907 werden aufgezeigt.
    Description: Abstract: First record of Devonaster Schuchert, 1914 in the German Lower Devonian (Asteroidea, Echinodermata). In this paper Devonaster Schuchert, 1914 is recorded for Germany for the first time. The genus, which belongs to the Xenasteridae Gregory, 1899, was previously only known from the Middle Devonian of North America (New York, Ontario). The new finds originate from neritic deposits of the Lower Emsian (Rhenish facies) in the Westerwald (Rhineland- Palatinate) and are thus clearly older. The relatively completely articulated specimens are presented as Devonaster wenndorfi n. sp. and Devonaster daadenensis n. sp. They show close relationships to the type species Devonaster eucharis (Hall, 1868) from the Middle Devonian of New York. The genus is compared with the genera Xenaster Simonowitsch, 1871 and Spaniaster Schöndorf, 1907, which also occur in the German Lower Devonian.
    Description: research
    Keywords: ddc:562 ; Unterdevon ; Rheinisches Schiefergebirge ; Westerwald ; Asteroidea
    Language: German
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    Untermiozäne Fossilgemeinschaften der Wiesbaden-Formation aus einem Tertiärprofil in Mainz (Mainz-Gruppe, Mainzer Becken, Deutschland) (2023)
    Details
    Publication Date: 2023-11-28
    Description: Vorgestellt wird ein hoch auflösendes, etwa 3,5 m mächtiges Profil aus der Wiesbaden- Formation. Die paläoökologische Interpretation der reichhaltigen Floren- und Faunengemeinschaften zeigt wiederholte Schwankungen der Salinität im aquatischen Ablagerungsraum, aber auch Klimaschwankungen an. Sedimentationsunterbrechungen, die an Durchwurzelungsspuren und einer Caliche?-Kruste erkennbar sind, erlauben eine Untergliederung des Profils in mehrere Profilabschnitte. Verantwortlich für das mehrfache Trockenfallen des Ablagerungsraumes und das anschließende Wiedereinsetzen von aquatischer Sedimentation sind neben klimatischen Faktoren wohl auch tektonisch bedingte relative Wasserspiegelschwankungen im nördlichen Oberrheingraben. Terrestrische Faunenelemente wie Landschnecken- oder Tetrapodenreste finden sich vor allem in den transgressiven Basisschichten im Anschluss an ein Trockenfallen des aquatischen Ablagerungsraumes und können vermutlich Tieren zugeordnet werden, die während der Auftauchphasen unmittelbar vor Ort lebten. Die transgressiven Basisschichten unmittelbar nach den Auftauchphasen beinhalten fast immer Fossilgemeinschaften mit stenöken Süßwasserorganismen und auch Brackwasser anzeigenden Organismen. Es wird angenommen, dass zu Beginn des Wiedereinsetzens der Sedimentation mehrfach zuerst ein Süßwassersee existierte, dieser aber, vermutlich infolge eines schwachen Meeresspiegelanstiegs, sehr bald von einem aus dem Oberrheingraben vordringenden brackischen Gewässer erreicht wurde, sodass sich Süßwasser- und Brackwasserfaunen ohne nennenswerte Umlagerung miteinander vermischen konnten.
    Description: Abstract: A high-resolutioned, approximately 3.5 m thick profile from the Wiesbaden-Formation is presented. The paleoecological interpretation of the rich flora and fauna assemblages shows repeated fluctuations in salinity in the aquatic depositional environment, but also climate fluctuations. Interruptions of sedimentation, which can be recognized by traces of root penetration and a caliche?-crust, allow a subdivision of the profile into several profile sections. In addition to climatic factors, tectonically caused relative fluctuations of the water level in the northern Upper Rhine Graben are probably responsible for the multiple drying out of the depositional environment and the subsequent resumption of aquatic sedimentation. Terrestrial faunal elements such as land snails or tetrapod remains are mainly found in the transgressive base layers following a drying out of the aquatic depositional area and can probably be assigned to animals that lived directly on site during the emergence phases. The transgressive base layers deposited immediately after the emergent phases mostly contain fossil assemblages with stenoecious freshwater organisms but also organisms indicating brackish water. It is assumed that at the beginning of the renewed sedimentation, a freshwater lake existed several times, but this was very soon reached by brackish waters encroaching from the Upper Rhine Graben, presumably as a result of a slight rise in sea level, so that freshwater and brackish water fauna could mix with each other without any significant rearrangement.
    Description: research
    Keywords: ddc:562 ; Mainzer Becken ; Wiesbaden-Formation ; Miozän ; TK 6015 ; Charophyten ; Foraminiferen ; Ostrakoden ; Mollusken ; Fische
    Language: German
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    Prof. Dr. Willy Theodor Stöhr (2023)
    Details
    Publication Date: 2023-11-28
    Description: Der Beitrag verfolgt die wichtigsten Stationen im Leben von Prof. Dr. Willy Th. Stöhr. Einen Schwerpunkt des Textes bildet Stöhrs Tätigkeit im Geologischen Dienst des Landes Rheinland-Pfalz (1957-1983). Damit lässt die Publikation gleichzeitig einen bedeutenden Teil der frühen Jahre der Bodenkunde beim Geologischen Landesamt Rheinland-Pfalz Revue passieren.
    Description: Abstract: The article traces the most important stages in the life of Prof. Dr. Willy Th. Stöhr. The main focus of the article is on Stöhr's work at the Geological Survey of Rhineland-Palatinate, Germany (1957-1983). At the same time, the article reviews a significant part of the early years of soil science at the Geological Survey as mentioned before.
    Description: research
    Keywords: ddc:631.49 ; Rheinland-Pfalz ; Bodenkartierung ; Biographie
    Language: German
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    Ermittlung von Hintergrundwerten für Grubenwässer des Steinkohlenbergbaus im Saarland (2023)
    Details
    Publication Date: 2023-11-28
    Description: Am Beispiel der Grubenwässer des Saarlandes wurden für die einzelnen Steinkohlengruben Hintergrundwerte mittels der Wahrscheinlichkeitsnetzmethode abgeleitet. Obwohl es sich bei den Grubenwässern um Mischwässer handelt, ist die Ableitung nach dieser Methode technisch möglich und liefert plausible Ergebnisse. Bei einigen Bergwerken wurden insbesondere für die Parameter elektrische Leitfähigkeit und Chlorid zwei Populationen festgestellt. Die Grubenwässer westlich der Saar sind gegenüber denen nordöstlich des Vorfluters durch höhere Mineralisationen gekennzeichnet.
    Description: Abstract: Using the example of the mine waters of the Saarland, background values were derived for the individual coal mines using the probability network method. Despite the fact that the mine waters are mixed waters, deriving values using this method is technically feasible and yields plausible results. In some mines, two populations were identified, particularly for the parameters of electrical conductivity and chloride. The mine waters west of the Saar River are characterized by higher mineralizations compared to those located northeast of the watercourse.
    Description: research
    Keywords: ddc:622.334 ; Saarland ; Grubenwässer ; Steinkohle
    Language: German
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    Environmental Earth Sciences Progress Report 2020 and Outlook 2021 (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-11-28
    Description: The present editorial 2020 continues the series of status reports in Environmental Earth Sciences (EES) in previous years 2017 and 2019 (Kolditz et al. in Environ Earth Sci 77: 8, 2018, Kolditz et al. in Environ Earth Sci 79: 11, 2020). The year 2020 coming to an end was heavily influenced by the COVID-19 pandemic affecting all areas of life including research work and, therefore, scientific publishing as well (“Introduction”). One bright spot which shows longevity of journals that produce a quality product is that Environmental Earth Sciences (EES) is celebrating its 45th anniversary of publication. To this extent EES continues the tradition to honor the most cited papers contributing to the 2020 Impact Factor (IF) (“Highly and most cited topics”) and provide information on the current status of EES as well as an outlook to 2021 (“Progress report”)
    Description: Helmholtz-Zentrum für Umweltforschung GmbH - UFZ (4215)
    Keywords: ddc:333.7 ; Environmental Earth Sciences (EES) ; Most cited papers ; Progress report ; 2020
    Language: English
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    Neue Erkenntnisse zur Rhynchonelliden-Gattung Xahetomus (Brachiopoda) aus dem Unterdevon der Mittelrhein-Region (2023)
    Details
    Publication Date: 2023-11-28
    Description: Das neue Brachiopoden-Taxon Xahetomus deltoides n. sp. aus dem Ober-Emsium des oberen Unterdevons wird beschrieben. Die verbesserten Kenntnisse über Xahetomus Sartenaer, 2009 ermöglichen die Revision der diagnostischen Merkmale. Ein neuer Fund weist das Vorkommen der Gattung bereits im mittleren Siegenium nach.
    Description: Abstract: New facts on the rhynchonellide genus Xahetomus (Brachiopoda) from the Lower Devonian of the Middle Rhine region (Rhenish Massif) are presented. The new brachiopod taxon Xahetomus deltoides n. sp. from the upper Emsian of the upper Lower Devonian is descibed. The improved knowledge about Xahetomus Sartenaer, 2009 allows the revision of diagnostic features. A new fossil record proves the occurrence of the genus already in the middle Siegenian.
    Description: research
    Keywords: ddc:562 ; Rheinisches Schiefergebirge ; Unterdevon ; Brachiopoden
    Language: German
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    Der Untere Muschelkalk im Raum Godendorf – Kersch – Udelfangen/Südeifel (2022)
    Details
    Publication Date: 2023-11-28
    Description: Der Muschelsandstein im Abbaubetrieb bei Ralingen-Kersch hat neben mächtigen massigen Werksteinen auch vielfältige Fossilien und Lebensspuren geliefert. Sie werden beschrieben und abgebildet. Ein vollmariner, aber dennoch zeitweise sehr flachgründiger Ablagerungsraum bildet sich ab. Innerhalb der gallo-ardennischen Randfazies-Abfolge des Unteren Muschelkalks (mu) der Trier-Luxemburger Bucht markiert die Werksteinzone ein besonderes Intermezzo. Umgeben ist es von den Hinterlassenschaften starker Erdbeben-Ereignisse, die aus dem überregionalen plattentektonischen Geschehen der tieferen Trias resultierten. Die lateral und vertikal hoch variable, z.T. auch lückenhafte mu-Schichtenfolge des Trier-Luxemburgischen Beckenrands wird dargelegt. Sie kann in vier Sequenzen untergliedert werden, die im Wechselspiel tiefer und hoher (relativer) Meeresspiegelstände entstanden. Nicht nur eustatische Gegebenheiten, sondern vor allem auch tektonische Ereignisse waren dabei prägend. Zwei besonders stark regressive Zeitintervalle sind weiträumig durch die akzentuierte Vorschüttung terrigener Sande und Tone und durch basale Schichtlücken gekennzeichnet. Auch deutliche Transgressionsereignisse mit weitem Onlap sind litho- und biofaziell nachzuvollziehen. Anhand der Fazies- und Mächtigkeitsmuster der einzelnen Sequenzen werden ihre unterschiedlichen Subsidenzmuster rekonstruiert und erläutert. Sie belegen die Wichtigkeit von vertikalen Schollenbewegungen, wie es ähnlich auch schon im Buntsandstein der Fall gewesen war. Dies erweist sich hier am Westrand des mitteleuropäischen Beckens ebenso wie im östlichen Beckenrandbereich in Polen. Unterstützt durch die sequenzstratigraphische Methodik ergibt sich nunmehr eine genauere bio- und – vor allem – lithostratigraphische Interngliederung, die eine verbesserte Korrelation mit der mu-Schichtenfolge (in der Westpfalz und) im hessischen und mitteldeutschen Beckeninneren erlaubt. Der Schichtbereich der Werksteinzone von Kersch entspricht der Terebratelzone. Hier im Trier-Luxemburgischen Randbecken ist er als tektonisch initiierter Tiefstands- Systemtrakt (LST) oberhalb einer Sequenzgrenze zu bewerten.
    Description: Abstract: The succession of the Muschelsandstein in the quarry near Ralingen-Kersch has yielded thick and massive stones (freestones) as well as numerous ichnospecies and other fossils. They are described and illustrated here. A fully marine, but nevertheless temporary shallow sedimentation area is documented. This succession (Werksteinzone) marks a very special intermezzo within the local gallo-ardennic border facies of the Lower Muschelkalk (mu). It is surrounded by the remnants of strong seismic events, which resulted from supraregional plate tectonics in lower Triassic. The whole mu-succession of the basin margin around here is described. It is laterally and vertically varying and regionally somewhat incomplete. Now it can be separated into four stratigraphic sequences, which generated during the interplay of low and high (relative) sea levels. Not only eustatic circumstances but mainly tectonic events had been important. Two intervals of strong regressions are indicated by widely spread terrigenous sands and clays and by gaps in the geologic record. Remarkably onlapping transgressive episodes can be traced as well, by litho- and biofacial properties. The respective sequences show individual patterns of lithofacies and thickness. By that their subsidence patterns can be reconstructed and explained genetically. They prove the importance of vertical tectonics, just as in the preceding Buntsandstein. This can be observed here at the western margin of the mid european basin as well as at the eastern margin area in Poland. Supported by sequence stratigraphic means a more detailed internal division is possible, which allows a better correlation to the mu-succession (in western Palatinate and) in the inner basinal areas of Hesse and Central Germany. The stratigraphic range of the Werksteinzone in Kersch corresponds to the Terebratelzone of the inner basin. Here in the individually conditioned Trier-Luxemburg basin area it can be interpreted as a Lowstand Systems Tract (LST) overlying a tectonically induced sequence boundary.
    Description: 1. Einführung 2. Lithostratigraphie des Unteren Muschelkalks im Untersuchungsgebiet 3. Bio- und Ichnofazies bei Kersch 4. Seismite im Unteren Muschelkalk 5. Die Beckenentwicklung und Sequenzstratigraphie des Unteren Muschelkalks der Trier- Luxemburger Bucht im überregionalen Vergleich 5.1 Vorbemerkungen 5.2 mu1-Sequenz (M1a-Sequenz) 5.3 mu2-Sequenz (M1b-Sequenz) 5.4 Grenzbereich mu2-/mu3-Sequenz 5.5 mu3-Sequenz (M1c-Sequenz) 5.6 mu4-Sequenz (M1d-Sequenz) und der mu/mm-Grenzbereich Schriften
    Description: research
    Keywords: ddc:554.3 ; Muschelkalk ; Eifel ; Lithostratigraphie ; Sequenzstratigraphie ; Fische ; TK 6205
    Language: German
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    Perspektiven einer nachhaltigen Meeresnutzung. Tauchen als Mensch-Natur(raum) Interaktion (2023)
    Institut für Geographie und Geologie der Universität Greifswald
    Details
    Publication Date: 2023-11-25
    Description: Dieser Sammelband umfasst verschiedene Arbeiten zum Thema Tauchsport und dessen Einfluss auf marine Ökosysteme. Aus verschiedenen interdisziplinären Perspektiven setzen sich die Autor*innen des Bandes mit dem Nutzen des Tauchsports für einen verbesserten marinen Artenschutz auseinander.
    Description: Der Druck dieser Publikation wurde aus dem Teilprojekt Fragmentierte Transformation des Interdisziplinären Forschungszentrums Ostseeraum finanziert.
    Description: Tauchtourismus in marinen Schutzgebieten als nachhaltige Meeresnutzung – Eine Fallstudie in den ägyptischen Northern Red Sea Islands5 ; A matter of affection? – The role of SCUBA divers’ emotions and nature affiliation in divers’ site-specific and everyday behaviour concerning coral reef conservation37 ; Perspektiven des Tauchens als Beitrag zu einer Ocean Literacy – Ergebnisse einer Fallstudie am Roten Meer (Soma Bay, Ägypten)64 ;
    Description: research
    Keywords: Tauchen ; Nachhaltigkeit ; Ocean Literacy ; Meeresschutz ; Ägypten
    Language: German
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    A Comprehensive Study of Infrasound Signals Detected from the Ingolstadt, Germany, Explosion of 1 September 2018 (2020)
    Springer International Publishing
    Details
    Publication Date: 2023-11-23
    Description: The explosion at the Ingolstadt oil refinery was widely recorded at seismic and infrasound stations deployed throughout Central Europe, to distances of several hundred to a thousand kilometres. This study focuses on the wealth of data recorded at infrasound stations in Central and Eastern Europe, while from the many detecting seismic stations within 400 km range, only seismic and seismo-acoustic arrivals at the close-in Gräfenberg array are considered here. Most of the infrasound stations are acoustic arrays enabling us to apply array processing techniques to determine relevant wave field parameters, such as backazimuth and slowness (resp. trace velocity). These parameters not only confirm the source direction, but also put constraints on the observed arrivals’ propagation modes. Wave field parameters suggest that we observe tropospheric arrivals to about 150 km and stratospheric and/or thermospheric returns for longer distances. 1D, 2D and 3D ray tracing predict tropospheric arrivals to westerly directions up to distances of 100 km, beyond which only thermospheric returns are obtained azimuth-independent beyond 250–300 km. Stratospheric returns do not follow from any of the increasingly complex ray tracing models. Parabolic equation propagation modeling however suggests that in a number of cases stratospheric ducting may be possible. However, neither the tropospheric seismo-acoustic arrivals at the Gräfenberg array nor the various arrivals at IMS station IS26 could be modeled. Therefore, the Ingolstadt explosion along with the observed infrasonic phases provide an excellent test bed to investigate our ability in realistically forecasting atmospheric wave propagation with existing algorithms and available atmospheric models.
    Keywords: ddc:551.5 ; Infrasound ; explosion ; atmospheric models ; propagation modeling ; stratospheric ducting
    Language: English
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    The Impact of Different Atmospheric CO2 Concentrations on Large Scale Miocene Temperature Signatures (2023)
    Hossain, Akil ; Knorr, Gregor ; Jokat, Wilfried ; [et al.]
    Details
    Publication Date: 2023-11-23
    Description: Based on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO〈sub〉2〈/sub〉 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO〈sub〉2〈/sub〉 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO〈sub〉2〈/sub〉 level of 450 ppm. An increase of atmospheric CO〈sub〉2〈/sub〉 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO〈sub〉2〈/sub〉 concentrations. At such CO〈sub〉2〈/sub〉 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO〈sub〉2〈/sub〉 increase from 280 to 450 ppm, in comparison to weaker warming for CO〈sub〉2〈/sub〉 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO〈sub〉2〈/sub〉 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO〈sub〉2〈/sub〉 forcing at a warmer Miocene background climate.
    Description: Key Points: At a CO〈sub〉2〈/sub〉 level of 450 ppm, a Miocene simulation shows a global mean surface warming of +3.1°C relative to the preindustrial state. Atmospheric CO〈sub〉2〈/sub〉 increase from 280 to 450 ppm causes a warming of ∼1.4°C, which is as strong as all other forcing factors combined. At higher atmospheric CO〈sub〉2〈/sub〉 levels, the Miocene climate shows a reduced polar amplification linked to a breakdown of seasonality in the Arctic.
    Description: Alfred Wegener Institute
    Description: Helmholtz Centre for Polar and Marine Research
    Description: https://doi.org/10.1594/PANGAEA.943430
    Description: https://github.com/FESOM/fesom2/
    Description: https://mpimet.mpg.de/en/science/modeling-with-icon/code-avilability
    Keywords: atmospheric CO2 ; Miocene ; Miocene temperature change ; polar amplification ; climate modeling ; Miocene bathymetry
    Language: English
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    The Climatology of Elevated Stratopause Events in the UA‐ICON Model and the Contribution of Gravity Waves (2023)
    Details
    Publication Date: 2023-11-23
    Description: The climatologies of the stratopause height and temperature in the UA‐ICON model are examined by comparing them to 17‐years (2005–2021) of Microwave Limb Sounder (MLS) observations. In addition, the elevated stratopause (ES) event occurrence, their main characteristics, and driving mechanisms in the UA‐ICON model are examined using three 30‐year time‐slice experiments. While UA‐ICON reasonably simulates the large‐scale stratopause properties similar to MLS observations, at polar latitudes in the Southern Hemisphere the stratopause is ∼8 K warmer and ∼3 km higher than observed. A time lag of about two months also exists in the occurrence of the tropical semiannual oscillation of the stratopause compared to the observations. ES events occur in ∼20% of the boreal winters, after major sudden stratospheric warmings (SSWs). Compared to the SSWs not followed by ES events (SSW‐only), the ES events are associated with the persistent tropospheric forcing and prolonged anomalies of the stratospheric jet. Our modeling results suggest that the contributions of both gravity waves (GW)s and resolved waves are important in explaining the enhanced residual circulation following ES events compared to the SSW‐only events but their contributions vary through the lifetime of ES events. We emphasize the role of the resolved wave drag in the ES formation as in the sensitivity test when the non‐orographic GW drag is absent, the anomalously enhanced resolved wave forcing in the mesosphere gives rise to the formation of the elevated stratopause at about 85 km.
    Description: Plain Language Summary: Using 17 years (2005–2021) of Microwave Limb Sounder (MLS) observations, we show negative (cooling stratopause temperatures and decreasing stratopause heights) trends in most regions and seasons. The largest negative trend in the stratopause temperature (by considering all regions and all seasons) is found in the Southern Hemisphere (SH)'s polar region during austral spring. The seasonal average of cooling rates is comparable in the mid‐latitudes of Northern Hemisphere and SH. In the UA‐ICON simulations, the elevated stratopause events (ESEs) occur after major sudden stratospheric warmings (SSWs). ESEs frequency is 2 events per decade in UA‐ICON simulations. Our results show that the wind reversal is stronger and long‐lasting in the ESEs compared to SSW‐only events. In addition, the easterlies extend to the mesosphere in the composites of ESEs, but the reversed winds are limited to below 60 km in the case of SSW‐only events. We show that the non‐orographic gravity wave drag induces anomalous residual circulation after SSW that causes the ESEs. We also show that the ESEs form even in the absence of non‐orographic gravity wave drag. In this case, the anomalous residual circulation is due to the anomalously enhanced resolved wave forcing in the mesosphere that gives rise to the formation of the ESEs at about 85 km.
    Description: Key Points: The largest stratopause trend is found in the Southern Hemisphere polar region during austral springbased on Microwave Limb Sounder observations. The suppression of gravity waves in UA‐ICON reveals the importance of resolvedwaves and their ability to compensate missing drag. In the polar regions, the simulated stratopause is too warm and the tropical semi‐annual oscillation is about two months out of phase.
    Description: Deutsche Forschungsgemeinschaft
    Description: Transregional Collaborative Research Centre
    Description: GACR
    Description: MS‐GWaves
    Description: https://code.mpimet.mpg.de/projects/iconpublic
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_ctrl
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_nonon
    Description: https://doi.org/10.26050/WDCC/UAICON_timesl_nosso
    Keywords: ddc:551.5 ; gravity waves ; elevated stratopause ; middle atmosphere
    Language: English
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    Can Offshore Meteoric Groundwater Generate Mechanical Instabilities in Passive Continental Margins? (2023)
    Details
    Publication Date: 2023-11-23
    Description: Offshore meteoric groundwater (OMG) has long been hypothesized to be a driver of seafloor geomorphic processes in continental margins worldwide. Testing this hypothesis has been challenging because of our limited understanding of the distribution and rate of OMG flow and seepage, and their efficacy as erosive/destabilizing agents. Here we carry out numerical simulations of groundwater flow and slope stability using conceptual models and evolving stratigraphy—for passive siliciclastic and carbonate margin cases—to assess whether OMG and its evolution during a late Quaternary glacial cycle can generate the pore pressures required to trigger mechanical instabilities on the seafloor. Conceptual model results show that mechanical instabilities using OMG flow are most likely to occur in the outer shelf to upper slope, at or shortly before the Last Glacial Maximum sea‐level lowstand. Models with evolving stratigraphy show that OMG flow is a key driver of pore pressure development and instability in the carbonate margin case. In the siliciclastic margin case, OMG flow plays a secondary role in preconditioning the slope to failure. The higher degree of spatial/stratigraphic heterogeneity of carbonate margins, lower shear strengths of their sediments, and limited generation of overpressures by sediment loading may explain the higher susceptibility of carbonate margins, in comparison to siliciclastic margins, to mechanical instability by OMG flow. OMG likely played a more significant role in carbonate margin geomorphology (e.g., Bahamas, Maldives) than currently thought.
    Description: Plain Language Summary: The flow of fresh to brackish groundwater has been proposed as an important process shaping the seafloor. However, we still have a poor understanding of how groundwater behaves in the sub‐seafloor and whether it can erode seafloor sediments. In this study, we test this hypothesis by using conceptual and realistic numerical models of two common types of seafloor margins—siliciclastic and carbonate—to assess the role of groundwater in making the seafloor susceptible to erosion. We show that the flow of groundwater offshore could have driven seafloor erosion close to the shelf break during the Last Ice Age, when sea level was lower than at present. Carbonate margins are more susceptible to this type of failure than siliciclastic margins. This may be explained by the higher variability in sediment properties across carbonate margins as well as the lower strength of their sediments. Groundwater has likely played an important role in shaping the seafloor in carbonate margins, and it may be responsible for landforms such as canyons, scars, and depressions in the Bahamas and the Maldives.
    Description: Key Points: Offshore meteoric groundwater (OMG) flow can drive mechanical instabilities in the outer shelf to upper slope. Such instabilities occur at, or shortly after, the Last Glacial Maximum sea‐level lowstand. Carbonate margins are more susceptible to mechanical instability by OMG than siliciclastic margins.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: https://doi.org/10.5281/zenodo.7094202
    Description: https://www.rocscience.com/software/slide2
    Description: https://figshare.com/s/5336d42d19ef771d4ad8
    Description: https://figshare.com/s/5027cd5ca22a7e96b3d1
    Keywords: ddc:551.3 ; offshore groundwater ; mechanical instability ; continental margins ; seafloor geomorphology ; siliciclastic ; carbonate
    Language: English
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    Toward Better Constrained Scattering Models for Natural Ice Crystals in the Visible Region (2023)
    Details
    Publication Date: 2023-11-23
    Description: In this work, we introduce a method for constraining the optical scattering models of natural ice crystals based on in‐situ measurements. Specifically the measured angular scattering functions for ice crystals can be used to compute a set of the asymmetry parameter (g) and the corresponding complexity parameter (C〈sub〉p〈/sub〉). It is demonstrated that the g‐C〈sub〉p〈/sub〉 relation can give valuable information on the morphology of ice crystal. The validity of the methods is shown from theoretical perspectives and the geometric‐optics ray‐tracing simulations. As an application, we investigate rimed ice crystals from in‐situ measurements and found that (a) the C〈sub〉p〈/sub〉 parameter is very well correlated with the surface riming degree and (b) only those models with both roughness and internal scattering can explain the observed g‐C〈sub〉p〈/sub〉 relation for rimed particles.
    Description: Plain Language Summary: Light scattering models of ice crystals are important for remote sensing and climate studies. Yet, many physical parameters, such as shape, aspect ratio, and inhomogeneity of the ice crystal can impose significant uncertainty in the single‐scattering properties predicted by light scattering models. To reduce such uncertainty and constrain the physical parameters in modeling, we introduce a novel method by analyzing the in‐situ measurement of the phase functions of ice crystals. We demonstrate the validity and usefulness of the method using both geometric ray‐tracing simulations and a case study on rimed crystals from two campaigns.
    Description: Key Points: A method is developed for analyzing in‐situ polar nephelometer measurements, aiming for constraining the light scattering models for natural ice crystal. Validity of the method is demonstrated by geometric‐optics ray‐tracing simulations and in‐situ measurements. A case study of rimed crystals measured in‐situ during two aircraft field campaigns using the Particle Habit Imaging and Polar Scattering probe is presented.
    Description: Helmholtz Association's Initiative and Networking Fund
    Description: https://doi.org/10.1594/PANGAEA.902611
    Description: https://doi.org/10.5065/D6639NKQ
    Description: https://zenodo.org/badge/latestdoi/440147565
    Keywords: ddc:551.5 ; light scattering ; ice crystals
    Language: English
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    In vitro cultivation of primary intestinal cells from Eisenia fetida as basis for ecotoxicological studies (2021)
    Riedl, Simon A. B. ; Völkl, Matthias ; Holzinger, Anja ; [et al.]
    Springer US
    Details
    Publication Date: 2023-11-23
    Description: The earthworm Eisenia fetida is a commonly used model organism for unspecific soil feeders in ecotoxicological studies. Its intestinal cells are the first to encounter possible pollutants co-ingested by the earthworm, which makes them prime candidates for studies of toxic effects of environmental pollutants on the cellular as compared to the organismic level. In this context, the aim of this study was to demonstrate the suitability of preparations of primary intestinal E. fetida cells for in vitro ecotoxicological studies. For this purpose, a suitable isolation and cultivation protocol was established. Cells were isolated directly from the intestine, maintaining 〉85% viability during subsequent cultivations (up to 144 h). Exposure to established pollutants and soil elutriates comprising silver nanoparticles and metal ions (Cu2+, Cd2+) induced a significant decrease in the metabolic activity of the cells. In case of microplastic particles (MP particles), namely 0.2, 0.5, 2.0, and 3.0 µm diameter polystyrene (PS) beads as well as 0.5 and 2.0 µm diameter polylactic acid (PLA) beads, no active uptake was observed. Slight positive as well as negative dose and size dependent effects on the metabolism were seen, which to some extent might correlate with effects on the organismic level.
    Keywords: ddc:631.4 ; Earthworm ; Eisenia fetida ; Environmental pollutants ; Microplastic ; Cytotoxicity ; Primary cells
    Language: English
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    Soil organic matter turnover rates increase to match increased inputs in grazed grasslands (2021)
    Stoner, Shane W. ; Hoyt, Alison M. ; Trumbore, Susan ; [et al.]
    Springer International Publishing
    Details
    Publication Date: 2023-11-23
    Description: Managed grasslands have the potential to store carbon (C) and partially mitigate climate change. However, it remains difficult to predict potential C storage under a given soil or management practice. To study C storage dynamics due to long-term (1952–2009) phosphorus (P) fertilizer and irrigation treatments in New Zealand grasslands, we measured radiocarbon (〈sup〉14〈/sup〉C) in archived soil along with observed changes in C stocks to constrain a compartmental soil model. Productivity increases from P application and irrigation in these trials resulted in very similar C accumulation rates between 1959 and 2009. The ∆〈sup〉14〈/sup〉C changes over the same time period were similar in plots that were both irrigated and fertilized, and only differed in a non-irrigated fertilized plot. Model results indicated that decomposition rates of fast cycling C (0.1 to 0.2 year〈sup〉−1〈/sup〉) increased to nearly offset increases in inputs. With increasing P fertilization, decomposition rates also increased in the slow pool (0.005 to 0.008 year〈sup〉−1〈/sup〉). Our findings show sustained, significant (i.e. greater than 4 per mille) increases in C stocks regardless of treatment or inputs. As the majority of fresh inputs remain in the soil for less than 10 years, these long term increases reflect dynamics of the slow pool. Additionally, frequent irrigation was associated with reduced stocks and increased decomposition of fresh plant material. Rates of C gain and decay highlight trade-offs between productivity, nutrient availability, and soil C sequestration as a climate change mitigation strategy.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: GNS Science
    Description: Max Planck Institute for Biogeochemistry (2)
    Description: https://github.com/ShaneStoner/Winchmore14C
    Keywords: ddc:631.4 ; Radiocarbon ; Soil carbon ; Soil modeling ; Carbon sequestration ; Transit time ; SoilR
    Language: English
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    Pre‐Eruptive Outgassing and Pressurization, and Post‐Fragmentation Bubble Nucleation, Recorded by Vesicles in Breadcrust Bombs From Vulcanian Activity at Guagua Pichincha Volcano, Ecuador (2023)
    Details
    Publication Date: 2023-11-23
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Breadcrust bombs formed during Vulcanian eruptions are assumed to originate from the shallow plug or dome. Their rim to core texture reflects the competition between cooling and degassing timescales, which results in a dense crust with isolated vesicles contrasting with a highly vesicular vesicle network in the interior. Due to relatively fast quenching, the crust can shed light on pre‐ and syn‐eruptive conditions prior to or during fragmentation, whereas the interior allows us to explore post‐fragmentation vesiculation. Investigation of pre‐ to post‐fragmentation processes in breadcrust bombs from the 1999 Vulcanian activity at Guagua Pichincha, Ecuador, via 2D and 3D textural analysis reveals a complex vesiculation history, with multiple, spatially localized nucleation and growth events. Large vesicles (Type 1), present in low number density in the crust, are interpreted as pre‐eruptive bubbles formed by outgassing and collapse of a permeable bubble network during ascent or stalling in the plug. Haloes of small, syn‐fragmentation vesicles (Type 2), distributed about large vesicles, are formed by pressurization and enrichment of volatiles in these haloes. The nature of the pressurization process in the plug is discussed in light of seismicity and ground deformation signals, and previous textural and chemical studies. A third population (Type 3) of post‐fragmentation small vesicles appears in the interior of the bomb, and growth and coalescence of Type 2 and 3 vesicles causes the transition from isolated to interconnected bubble network in the interior. We model the evolution of viscosity, bubble growth rate, diffusion timescales, bubble radius and porosity during fragmentation and cooling. These models reveal that thermal quenching dominates in the crust whereas the interior undergoes a viscosity quench caused by degassing, and that the transition from crust to interior corresponds to the onset of percolation and development of permeability in the bubble network.〈/p〉
    Description: Plain Language Summary: Breadcrust bombs are volcanic ejecta formed during explosive volcanic eruptions by rapid cooling of the exterior (the crust) and slow cooling of the interior that causes gas loss, bubble growth and cracking of the exterior. The rapidly cooled crust preserves characteristics of the magma prior to explosion. We study here the variations in porosity and vesicle properties from crust to interior in breadcrust bombs from the Guagua Pichincha volcano in Ecuador. Our results shed light on the pre‐eruptive conditions in the magma prior to explosive activity, and on the post‐fragmentation evolution of the bomb interior by bubble formation.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Vesicle textures in breadcrust bombs correlate with pre‐ to post‐fragmentation degassing processes during Vulcanian eruptions〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Large isolated vesicles preserved in the crust record a pre‐eruptive episode of outgassing and pressurization prior to fragmentation〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Small vesicles provide insights into post‐fragmentation onset of permeability from the crust to the interior〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: ERC
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: National Science Foundation
    Description: German Research Foundation
    Description: https://doi.org/10.26022/IEDA/112846
    Keywords: ddc:552 ; breadcrust bombs ; Vulcanian eruptions ; vesicle number density ; vesiculation ; bubble nucleation ; fragmentation
    Language: English
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    Influence of Inner Surface Roughness on the Spectral Induced Polarization Response—A Numerical Study (2023)
    Details
    Publication Date: 2023-11-23
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Spectral induced polarization (SIP) laboratory measurements on water‐saturated rocks show a strong correlation between the electrical polarization strength and the inner surface area of rocks. We investigate the influence of inner surface roughness on the SIP response by simulating the frequency‐dependent complex conductivity of micro‐scale rock models. Starting with smooth grain models, we introduce surface roughness using two different approaches: increasing the surface roughness in a fractal‐like manner, and creating random surface structures, resulting in more natural‐looking surfaces. We find that surface roughness has two distinct effects on the SIP response: (a) a shift in the position and magnitude of the primary relaxation frequency to lower frequencies and lower magnitudes, respectively, and (b) the formation of secondary polarizations above the polarization frequency of the primary polarization. We also compare the relaxation time and normalized chargeability obtained by Debye decomposition and the imaginary conductivity at 1 Hz of our models with mechanistic models and empirical relations. We point out the congruences and offer explanations for the discrepancies between our models and the empirical observations. We conclude that the results of our study are applicable to real rocks and that the SIP method has the potential to detect inner surface roughness. However, the SIP method it not able to discriminate between signals from rough particles and a distribution of smooth particles.〈/p〉
    Description: Plain Language Summary: The spectral induced polarization method measures the electrical conductivity of the subsurface at depths of investigation ranging from a few dm to several 100 m. The potential of the method to detect mineral resources, contamination, microbial activity, etc. makes it a promising tool for today's environmental challenges. However, due to the complexity of the underlying physical and chemical processes the interpretation of SIP measurements often remains qualitative. Mathematical and mechanistic models used to describe the processes are usually simplified with respect to geometry, chemistry, and physical properties. In this study, we use computer simulations to investigate the surfaces of spherical particles (grains). After simulating the SIP response of models with smooth and rough surfaces, we analyze the influence of surface roughness on the SIP response. We find that surface roughness causes distinct changes in the SIP response compared to the smooth grain. However, we also find that this introduces an ambiguity in the interpretation of SIP data.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Inner surface roughness of rocks has substantial impact on spectral induced polarization response〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Surface roughness shifts the primary polarization peak to lower frequencies〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Surface roughness causes additional polarizations above the primary peak frequency〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: https://doi.org/10.5281/ZENODO.7049722
    Keywords: ddc:550 ; SIP ; surface ; roughness
    Language: English
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    Wind Power Input to Ocean Near‐Inertial Waves Diagnosed From a 5‐km Global Coupled Atmosphere‐Ocean General Circulation Model (2023)
    Details
    Publication Date: 2023-11-27
    Description: Using the 5 km coupled general circulation model ICON, the surface internal wave energy source, crucial for the oceanic circulation, is quantified as the wind‐induced wave energy flux that radiates from the mixed layer bottom (MLB) into the ocean interior. Our result lowers the previous estimates of the wind power input to surface near‐inertial motions from up to more than 1 TW down to about 0.23–0.27 TW, depending on season. We point out that the estimate of the wind input to ocean depends not only on the wind stress used—as suggested by previous studies—but also on the ocean model used. While the surface currents in a slab ocean model or a non‐eddying ocean circulation model are strongly determined by the wind forcing, the surface currents in the 5 km ICON model can be more strongly determined by internal instability process (eddy) than by wind stress forcing from less‐extreme weather disturbances. The resulting more or less random alignment of surface current and wind stress can presumably lead to a lower wind input to surface near‐inertial motions. Of the surface wave energy source, about 30% is fluxed down into the interior ocean. This percentage roughly doubles those from previous studies, due to the stronger wave energy flux related to stronger inertial waves generated by the tropical cyclones simulated by the 5 km ICON model. Overall, the low wind input at near‐inertial frequencies produces a wind‐induced wave energy source at the MLB that is well below 0.1 TW.
    Description: Plain Language Summary: For maintaining the oceanic overturning circulation, energy is needed to mix the dense water up and light water down. The main energy source for mixing arises from breaking of internal waves. A considerable portion of this source comes from waves excited by winds at the sea surface. This paper quantifies this wave energy source based on a frontier simulation of a coupled atmosphere‐ocean general circulation model at a horizontal resolution of 5 km. This model is capable to simulate tropical cyclones (hurricanes and typhoons) and less‐extreme small‐scale and short‐living weather disturbances and oceanic mesoscale eddies, which were not represented by the models used in most of the previous studies. Taking these new features into account, we find that the wind‐induced wave energy source is less than 0.1 TW.
    Description: Key Points: Relatively low wind power input to near‐inertial motions in a 5 km global coupled simulation. Energy flux radiating from the mixed layer bottom as interior wave energy source. Strong internal waves excited by tropical cyclones simulated by a 5 km global coupled general circulation model.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: http://hdl.handle.net/21.11116/0000-000A-C1FA-2
    Keywords: ddc:551.5 ; wind‐induced wave energy source ; km‐scale coupled GCM ; internal waves generated by tropical cyclones
    Language: English
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    The 12 December 2017 Baumgarten Gas Hub Explosion: A Case Study on Understanding the Occurrence of a Large Infrasound Azimuth Residual and a Lack of Seismic Observations (2020)
    Springer International Publishing
    Details
    Publication Date: 2023-11-27
    Description: The Baumgarten explosion occurred on 12 December 2017 at a gas storage site about 30 km east of Vienna, Austria. Acoustic arrivals from this accidental surface explosion were detected at dozens of stations of the AlpArray seismic network to distances up to 150 km, mainly in easterly directions. Thus it was expected that the Hungarian infrasound array PSZI located about 230 km to the east-southeast of Baumgarten would detect this acoustic wave as well. Standard progressive multichannel correlation processing and frequency-wavenumber analysis identified a signal emerging at 7:57:55 UTC from an azimuth of 296°–300° and with trace-velocity 〉 400 m/s. The extraordinarily high trace-velocity and excessive backazimuth residual, relative to the explosion site direction of 282°, however cast strong doubts on the arrival’s connection to the Baumgarten event. Accounting for the effect of non-planar geometry of the infrasound array results in a reduction of the azimuth residual by half. Additionally, 2D and 3D raytracing methods are used including the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric model to further explain the remaining azimuth residual as well as to elucidate the large trace velocity estimates. The prevailing stratospheric winds in excess of 150 m/s are identified as the underlying cause. Including both factors the initial azimuth residual of up to 18° decreases to ~ 4°, allowing to associate the infrasound signal at PSZI with the Baumgarten event. Finally, the data from a seismic station at 30 km range is re-investigated for magnitude estimation. The local magnitude of ML 〈 1.0 explains well the scarcity of seismic observations within 50 km range, where three or four stations show signals, mainly consisting of Rg-type surface waves, but no body waves.
    Description: https://www.geofon.gfz-potsdam.de/doi/network/HN
    Description: https://doi.org/10.14470/UA114590
    Description: https://www.geofon.gfz-potsdam.de/doi/network/SK
    Description: https://www.ecmwf.int/
    Description: https://www.github.com/LANL-Seismoacoustics/GeoAc
    Keywords: ddc:551 ; Infrasound ; Baumgarten explosion ; array data processing ; backazimuth residual ; atmospheric sound propagation ; detection threshold
    Language: English
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    Ultrasonic Echo Localization Using Seismic Migration Techniques in Engineered Barriers for Nuclear Waste Storage (2021)
    Springer US
    Details
    Publication Date: 2023-11-27
    Description: In the framework of non-destructive-testing advanced seismic imaging techniques have been applied to ultrasonic echo data in order to examine the integrity of an engineered test-barrier designed to be used for sealing an underground nuclear waste disposal site. Synthetic data as well as real multi-receiver ultrasonic data acquired at the test site were processed and imaged using Kirchhoff prestack depth migration reverse time migration (RTM). In general, both methods provide a good image quality as demonstrated by various case studies, however deeper parts within the test barrier containing inclined reflectors were reconstructed more accurately by RTM. In particular, the image quality of a specific target reflector at a depth of 8 m in the test-barrier has been significantly improved compared to previous investigations using synthetic aperture focusing technique, which justifies the considerable computing time of this method.
    Description: Technische Universität Bergakademie Freiberg (3135)
    Keywords: ddc:622.1 ; Echo localization ; Seismic migration ; Reverse time migration ; Kirchhoff migration ; Engineered barrier ; Imaging
    Language: English
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    Large‐scale mass movements recorded in the sediments of Lake Hallstatt (Austria)–evidence for recurrent natural hazards at a UNESCO World Heritage site (2022)
    Lauterbach, Stefan ; Strasser, Michael ; Kowarik, Kerstin ; [et al.]
    Details
    Publication Date: 2023-11-27
    Description: The Bronze to Iron Age underground salt mining complex of Hallstatt (Austria) is widely recognised for its cultural importance and wealth of archaeological artefacts. However, while the daily life in the salt mines is archaeologically well documented and environmental effects of the mining activity have been investigated recently, the impact of natural hazards on the prehistoric mining community is still poorly understood. For instance, while it is well established that the prehistoric underground mines have repeatedly been destroyed by large‐scale mass movements, only little is known about the characteristics and extent of these events as well as about mass‐movement recurrence during more recent times. To shed light on past mass‐movement activity in the vicinity of the Hallstatt salt mines, we investigated sediment cores from adjacent Lake Hallstatt. Within the regular lake sediments we identified three large‐scale event deposits, which are interpreted to originate from spontaneous or seismically induced mass movements in the mid‐19th and late 9th century ce and the mid‐4th century bce. While the age of the latter event is in good agreement with the abandonment of the famous Iron Age cemetery at Hallstatt, the younger events indicate that large‐scale mass movements also occurred repeatedly during the Common Era.
    Description: Freunde des Naturhistorisches Museums Wien
    Description: Austrian Science Fund http://dx.doi.org/10.13039/501100002428
    Description: Austrian Academy of Sciences
    Description: German Archaeological Institute
    Keywords: ddc:551.3 ; Archaeology ; European Alps ; lake sediments ; mass movements ; prehistoric mining
    Language: English
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  • 90
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    Modelling cometary meteoroid stream traverses of the Martian Moons eXploration (MMX) spacecraft en route to Phobos (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-11-27
    Description: The Martian Moons Exploration (MMX) spacecraft is a JAXA mission to Mars and its moons Phobos and Deimos. MMX will be equipped with the Circum-Martian Dust Monitor (CMDM) which is a newly developed light-weight (650g) large area (1m〈sup〉2〈/sup〉) dust impact detector. Cometary meteoroid streams (also referred to as trails) exist along the orbits of comets, forming fine structures of the interplanetary dust cloud. The streams consist predominantly of the largest cometary particles (with sizes of approximately 100μm to 1 cm) which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the detection conditions of cometary dust stream particles with CMDM during the MMX mission in the time period 2024 to 2028. The model predicts traverses of 12 cometary meteoroid streams with fluxes of 100μm and bigger particles of at least 10〈sup〉-3〈/sup〉m〈sup〉-2〈/sup〉day〈sup〉-1〈/sup〉 during a total time period of approximately 90 days. The highest flux of 0.15m〈sup〉-2〈/sup〉day〈sup〉-1〈/sup〉 is predicted for comet 114P/Wiseman-Skiff in October 2026. With its large detection area and high sensitivity CMDM will be able to detect cometary meteoroid streams en route to Phobos. Our simulation results for the Mars orbital phase of MMX also predict the occurrence of meteor showers in the Martian atmosphere which may be observable from the Martian surface with cameras on board landers or rovers. Finally, the IMEX model can be used to study the impact hazards imposed by meteoroid impacts onto large-area spacecraft structures that will be particularly necessary for crewed deep space missions.
    Description: Max Planck Institute for Solar System Research (2)
    Keywords: Comets ; Meteoroid trails ; Meteoroid streams ; Interplanetary dust ; Martian moons ; Phobos ; Deimos ; Martian Moons Exploration ; MMX
    Language: English
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    On the Dynamical Importance of Gravity Wave Sources Distributed Over Different Heights in the Atmosphere (2023)
    Details
    Publication Date: 2023-11-27
    Description: Gravity waves (GWs) are generated at all altitudes in the atmosphere, but sources above the lower stratosphere are rarely considered by parameterizations employed in general circulation models. This study assesses the potential impact on the thermosphere produced by small‐scale waves originating at different heights. Within the proposed numerical framework, GW sources are represented by wave momentum forcing, whose values are expressed relative to the forcing required to obtain typical wave spectra around the tropopause. The relative importance of tropospheric and extra‐tropospheric sources and the response in the thermosphere are studied in a series of sensitivity experiments. They demonstrate that the accumulation of wave momentum steeply drops with height as a consequence of decreasing density, even when the forcing is maintained at a uniform level throughout the middle atmosphere. When a broad spectrum is forced at twice the tropospheric rate, the thermospheric drag is increased by only a factor of two, and that increase is produced by waves that were forced in the lower stratosphere. With increasing altitude, vertically localized sources contribute progressively less. For example, for GWs excited near the mesopause to produce an impact comparable with that due to waves propagating from below, the forcing must be orders of magnitude stronger than in the troposphere. The estimated forcing of the so‐called secondary harmonics by breaking primary waves is much weaker, such that the systematic dynamical effect of secondary waves in the thermosphere is negligible compared to that of the primary GWs generated in the troposphere.
    Description: Plain Language Summary: Multiple observations demonstrate that gravity waves (GWs) are generated at all atmospheric levels, however numerical general circulation models employing parameterizations that account for wave sources only in the troposphere are able to reproduce the state and dynamics of the middle and upper atmosphere reasonably well. Assessing the role of GWs generated above the troposphere is extremely challenging, because such waves are difficult to separate from those of tropospheric origin in observations. The mechanisms of wave generation in the middle atmosphere are very complex and not fully understood. We developed a numerical framework, in which the strength of the extra‐tropospheric sources is represented by multiples of those in the troposphere. In the series of sensitivity tests, we demonstrate that the contribution of sources to the total wave momentum drops with height following the density decrease, and that the tropospheric sources capture the major part of the total momentum and of the associated GW drag in the thermosphere. One of the conclusions of this study is that the impact in the thermosphere of secondary waves, which are believed to be excited near the mesopause, is negligible compared to that of primary waves propagating from the troposphere.
    Description: Key Points: A framework for assessing impacts of gravity waves generated by sources distributed over all heights in the middle atmosphere is developed. The thermospheric response to sources above the tropopause is primarily produced by waves generated in the lower. stratosphere Localized sources produce negligible thermospheric drag unless the forcing is orders of magnitude stronger than in the troposphere.
    Description: Earth Sciences Division http://dx.doi.org/10.13039/100014573
    Description: https://kauai.ccmc.gsfc.nasa.gov/instantrun/hwm
    Description: https://ccmc.gsfc.nasa.gov/modelweb/models/nrlmsise00.php
    Keywords: ddc:551.5 ; gravity waves ; wave sources ; thermosphere ; secondary waves ; middle atmosphere
    Language: English
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  • 92
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    Seismic and Tsunamigenic Characteristics of a Multimodal Rupture of Rapid and Slow Stages: The Example of the Complex 12 August 2021 South Sandwich Earthquake (2022)
    Details
    Publication Date: 2023-11-27
    Description: On 12 August 2021, a 〉220 s lasting complex earthquake with M〈sub〉w〈/sub〉 〉 8.2 hit the South Sandwich Trench. Due to its remote location and short interevent times, reported earthquake parameters varied significantly between different international agencies. We studied the complex rupture by combining different seismic source characterization techniques sensitive to different frequency ranges based on teleseismic broadband recordings from 0.001 to 2 Hz, including point and finite fault inversions and the back‐projection of high‐frequency signals. We also determined moment tensor solutions for 88 aftershocks. The rupture initiated simultaneously with a rupture equivalent to a M〈sub〉w〈/sub〉 7.6 thrust earthquake in the deep part of the seismogenic zone in the central subduction interface and a shallow megathrust rupture, which propagated unilaterally to the south with a very slow rupture velocity of 1.2 km/s and varying strike following the curvature of the trench. The slow rupture covered nearly two‐thirds of the entire subduction zone length, and with M〈sub〉w〈/sub〉 8.2 released the bulk of the total moment of the whole earthquake. Tsunami modeling indicates the inferred shallow rupture can explain the tsunami records. The southern segment of the shallow rupture overlaps with another activation of the deeper part of the megathrust equivalent to M〈sub〉w〈/sub〉 7.6. The aftershock distribution confirms the extent and curvature of the rupture. Some mechanisms are consistent with the mainshocks, but many indicate also activation of secondary faults. Rupture velocities and radiated frequencies varied strongly between different stages of the rupture, which might explain the variability of published source parameters.
    Description: Plain Language Summary: The earthquake of 12 August 2021 along the deep‐sea trench of the South Sandwich Islands in the South Atlantic reached a magnitude of 8.2 and triggered a tsunami. The automatic earthquake parameter determination of different agencies showed very different results shortly after the earthquake and partially underestimated the tsunami potential of the earthquake. A possible reason was the complex rupture process and that the tsunami was generated by a long and shallow slow slip rupture sandwiched between more conventional fast slip subevents at its northern and southern ends. In addition, the fault surface, which extended over 450 km, was highly curved striking 150°–220°. We investigated the different components of the seismic wavefields in different frequency ranges and with different methods. The analysis shows how even complex earthquakes can be deciphered by combining analyzing methods. The comparison with aftershocks and the triggered tsunami waves confirms our model that explains the South Sandwich rupture by four subevents in the plate boundary along the curved deep‐sea trench. Here, the depth, rupture velocities, and slip on each segment of the rupture vary considerably. The method can also be applied to other megathrust earthquakes and help to further improve tsunami warnings in the future.
    Description: Key Points: A combination of multiple approaches, inversion setups, and frequency ranges deciphered the complex earthquake of 2021 South Sandwich. The rupture consisted of four subevents with the largest occurring as a shallow slow rupture parallel to the South Sandwich Trench. Forward modeling proves that the large, shallow thrust subevent caused the recorded tsunami.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Agencia Nacional de Investigación y Desarrollo http://dx.doi.org/10.13039/501100020884
    Description: https://ds.iris.edu/wilbert3/find_event
    Description: https://www.usgs.gov/natural-hazards/earthquake-hazards/lists-maps-and-statistics
    Description: http://www.ioc-sealevelmonitoring.org/
    Description: https://doi.org/10.7289/V5C8276M
    Description: https://www.gfz-potsdam.de/en/software/tsunami-wave-propagations-easywave
    Keywords: ddc:551.22 ; 2021 South Sandwich Earthquake ; seismic characteristics ; tsunamigenic characteristics
    Language: English
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    Systematic Across‐Arc Variations of Molybdenum Isotopes in a Fluid‐Dominated Subduction Zone System (2023)
    Details
    Publication Date: 2023-11-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Mass‐dependent Mo isotope variations are a promising new tracer to study magmatic processes in different geological settings. We report the first Mo isotope data for the Kamchatka arc system in the Northwest Pacific, comprising basaltic lavas of a complete Southeast‐Northwest traverse from the volcanic arc front through to the back arc region. The majority of volcanic centers investigated directly override the Hawaii‐Emperor Seamount Chain, which is currently being subducted underneath the arc system. Our Mo isotope data show systematic trends with Ce/Pb, Ce/Mo, Nb/Zr, La/Sm, and 〈sup〉143〈/sup〉Nd/〈sup〉144〈/sup〉Nd ratios from the volcanic arc front to the back arc. Arc front lavas have higher δ〈sup〉98/95〈/sup〉Mo and lower Ce/Pb, Ce/Mo, Nb/Zr, La/Sm compared to back arc lavas. Because the involvement of subducted sediments can be excluded, we attribute the observed variations to a change in the mantle source composition from the arc front to the back arc regions. The isotopic and chemical budget of arc front lavas is dominated by a slab fluid component (high δ〈sup〉98/95〈/sup〉Mo, low Ce/Pb, Ce/Mo), whereas mantle‐like Ce/Pb, Ce/Mo, elevated Nb/Zr and La/Sm in the back arc samples suggest an enriched mantle source. Combined δ〈sup〉98/95〈/sup〉Mo, Nd, and Pb isotope data in back arc lavas are very similar to those observed for modern ocean island basalts from Hawaii. We thus explore the possibility that the back arc mantle was contaminated by a Hawaii‐type, enriched asthenospheric mantle component from the subducted Hawaii‐Emperor Seamount Chain.〈/p〉
    Description: Plain Language Summary: In subduction zones, tectonic plates—tens of kilometers thick and making up the outer shell of our planet—are on a collision course. Although the absolute convergence rates of these plates are minute (a few cm/year), the forces in this process are so large that one plate is pushed under the other, causing the lower plate to be recycled into the Earth's mantle over time scales of millions of years. The tangible consequences are high‐magnitude earthquakes and large‐volume volcanic eruptions along these convergent plate margins. It is thus important to better understand the geological processes that operate in subduction zones. Here, we have studied the chemical and isotopic composition of volcanic rocks from the Kamchatka subduction zone. Our results confirm that water, locked into the subducting plate while residing on the surface, is released into the hot, overlying mantle after subduction, causing the formation of large volumes of magma that eventually erupt in volcanoes on the Kamchatka Peninsula. Our data also indicate that the subducting plate, once pushed into the mantle, is being ripped apart, allowing buoyant mantle material from greater depth to rise and contribute to the large‐scale volcanism observed along this convergent plate margin.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Molybdenum isotope systematics in arc basalts from Kamchatka are consistent with presence of a slab‐derived fluid in their mantle source〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Back arc basalts also show contribution from a geochemically enriched source〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Combined Mo, Nd, and Pb isotope and trace element data for back arc basalts suggest involvement of Hawaii‐type asthenospheric mantle〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.25625/P5BBFL
    Keywords: ddc:551.9 ; molybdenum isotopes ; slab fluid ; enriched mantle ; subduction ; Kamchatka ; Hawaii
    Language: English
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    Constraints for the Martian Crustal Structure From Rayleigh Waves Ellipticity of Large Seismic Events (2023)
    Details
    Publication Date: 2023-11-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉For the first time, we measured the ellipticity of direct Rayleigh waves at intermediate periods (15–35 s) on Mars using the recordings of three large seismic Martian events, including S1222a, the largest event recorded by the InSight mission. These measurements, together with P‐to‐s receiver functions and P‐wave reflection times, were utilized for performing a joint inversion of the local crustal structure at the InSight landing site. Our inversion results are compatible with previously reported intra‐crustal discontinuities around 10 and 20 km depths, whereas the preferred models show a strong discontinuity at ∼37 km, which is interpreted as the crust‐mantle interface. Additionally, we support the presence of a shallow low‐velocity layer of 2–3 km thickness. Compared to nearby regions, lower seismic wave velocities are derived for the crust, suggesting a higher porosity or alteration of the whole local crust.〈/p〉
    Description: Plain Language Summary:: As never before on Mars, we measured the characteristics of seismic waves traveling along the Martian surface that carry information about the crustal structure at the InSight site. We combined these measurements with two other local‐scale independent observations to derive a consolidated model for the crust underneath the InSight lander. Our results suggest a Martian crust with 4 layers and, particularly, one thin layer of about 2 km thickness close to the surface. The crust‐mantle discontinuity was found at ∼37 km depth, where the sharpest change in seismic wave velocity is observed. Overall, the seismic wave velocities of the local Martian crust at the InSight site are lower than those derived in other regions on Mars, which suggests a higher porosity or local alteration.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Rayleigh waves ellipticity was measured between periods 15–35 s at the InSight landing site using large seismic events, including S1222a〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉A 4‐layer crust, including a shallow low‐velocity layer, is required to explain the ellipticity, receiver functions and P‐wave lag times〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Low crustal velocities are derived for the InSight site, which may be due to high porosity or heavy alteration at local scale〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: National Aeronautics and Space Administration
    Description: Agence Nationale de la Recherche http://dx.doi.org/10.13039/501100001665
    Description: https://doi.org/10.12686/a19
    Description: https://doi.org/10.18715/SEIS.INSIGHT.XB_2016
    Description: https://doi.org/10.7914/SN/BQ
    Description: https://www.globalcmt.org/CMTsearch.html
    Description: https://github.com/scarrascom/Rellipy
    Description: https://doi.org/10.5281/zenodo.8051337
    Description: http://www.geopsy.org/
    Keywords: ddc:523 ; martian crust ; marsquakes ; Rayleigh waves ellipticity ; receiver functions
    Language: English
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    Carbonate platform drowning caught in the act: The sedimentology of Saya de Malha Bank (Indian Ocean) (2022)
    Betzler, Christian ; Lindhorst, Sebastian ; Reijmer, John J. G. ; [et al.]
    Details
    Publication Date: 2023-11-27
    Description: Mesophotic reefs, hardgrounds and current‐controlled pelagic to hemipelagic carbonates are facies marking carbonate platform drowning successions, irrespective of the factors controlling this evolution. A modern analogue of a carbonate platform in a state of drowning, where these facies occur has not been properly reported on to date. In the present study, the sedimentary environments of the Saya de Malha Bank are characterized using a multi‐disciplinary approach including sedimentology, hydroacoustics, seismics and oceanography. The Saya de Malha Bank edifice with a surface of 40 808 km〈sup〉2〈/sup〉 is located in the tropical Indian Ocean and lies in a water depth of 8 to 300 m extending from the surrounding more than 2000 m deep ocean floor, with no reef reaching the sea surface. Mesophotic coral and red algal facies co‐exist with hemipelagic and bioclastic sands, together with a hardground. Ocean currents and internal waves are identified as major sedimentological controlling factors in the absence of elevated nutrient influx. Many features distributed along the present‐day Saya de Malha Bank were described from studies presenting fossil examples of carbonate platform drowning. The results herein can therefore be applied to other drowning examples, in some cases allowing for more accurate interpretation of the stratigraphic record.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:552.58 ; Internal waves, Mascarene Plateau ; mesophotic reefs ; South Equatorial Current
    Language: English
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    Ingenieurgeologische Klassifizierung der Locker-, Halbfest- und Festgesteine von Rheinland-Pfalz (2022)
    Details
    Publication Date: 2023-12-06
    Description: Für das Bundesland Rheinland-Pfalz wurden erstmals Ingenieurgeologische Klassen für den Untergrund aufbauende Böden und Gesteine entwickelt. Grundlage hierfür ist die lithostratigraphische Generallegende aller geologischen Einheiten von Rheinland-Pfalz. Insgesamt wurden 21 Ingenieurgeologische Klassen für Lockergesteine, Halbfestgesteine und Festgesteine definiert. Bei der Entwicklung wurden rheinland-pfälzische Besonderheiten des geologischen Untergrunds berücksichtigt. Dies betrifft insbesondere die im Bundesland flächig verbreiteten Vulkanite. Mit den Ingenieurgeologischen Klassen sollen grundsätzliche flächenhafte Aussagen zum Baugrund (Bebaubarkeit) sowie zu verschiedenen Untergrundgefahren ermöglicht werden. Dies betrifft insbesondere die Anfälligkeiten des Untergrundes gegenüber Rutschungen, Setzungen, der Quell-/ Schrumpfempfindlichkeit, Erdfällen und der Verwitterung sowie das Vorhandensein organischer Anteile. Der Beitrag enthält ein erstes Beispiel für eine Ingenieurgeologische Karte und eine Karte der Rutschungsanfälligkeit für ein Gebiet im Mainzer Becken.
    Description: Abstract: For the first time engineering geological classes for the subsoils and rocks were developed for the federal state of Rhineland-Palatinate. The basis for this is the lithostratigraphic general legend of all geological units of Rhineland-Palatinate. A total of 21 engineering geological classes were defined for unconsolidated rocks, semisolidated rocks and solid rocks. Rhineland-Palatinate specifics of the geological subsurface were taken into account during the development. This concerns in particular the volcanic rocks which are widespread in the federal state. The engineering geology classes are intended to enable basic area-related statements to be made on the subsoil (buildability) as well as on various subsoil hazards. This concerns in particular the susceptibility of the subsoil to landslides, subsidence, swelling/shrinkage sensitivity, sinkholes and weathering as well as the presence of organic components. The paper contains a first example of an engineering geology map and a landslide susceptibility map for an area in the Mainz Basin.
    Description: research
    Keywords: ddc:554.3 ; Rheinland-Pfalz ; Ingenieurgeologie ; Baugrund
    Language: German
    Type: doc-type:article , publishedVersion
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    Microphysical Pathways Active Within Thunderstorms and Their Sensitivity to CCN Concentration and Wind Shear (2023)
    Details
    Publication Date: 2023-11-02
    Description: The impact of cloud condensation nuclei (CCN) concentration on microphysical processes within thunderstorms and the resulting surface precipitation is not fully understood yet. In this work, an analysis of the microphysical pathways occurring in these clouds is proposed to systematically investigate and understand these sensitivities. Thunderstorms were simulated using convection‐permitting (1 km horizontal grid spacing) idealized simulations with the ICON model, which included a 2‐moment microphysics parameterization. Cloud condensation nuclei concentrations were increased from 100 to 3,200 CCN/cm3, in five different wind shear environments ranging from 18 to 50 m/s. Large and systematic decreases of surface precipitation (up to 35%) and hail (up to 90%) were found as CCN was increased. Wind shear changes the details, but not the sign, of the sensitivity to CCN. The microphysical process rates were tracked throughout each simulation, closing the mass budget for each hydrometeor class, and collected together into “microphysical pathways,” which quantify the different growth processes leading to surface precipitation. Almost all surface precipitation occurred through the mixed‐phase pathway, where graupel and hail grow by riming and later melt as they fall to the surface. The mixed‐phase pathway is sensitive to CCN concentration changes as a result of changes to the riming rate, which were systematically evaluated. Supercooled water content was almost insensitive to increasing CCN concentration, but decreased cloud drop size led to a large reduction in the riming efficiency (from 0.79 to 0.24) between supercooled cloud drops and graupel or hail, resulting in less surface precipitation.
    Description: Plain Language Summary: The amount of rain and hail from thunderstorms can be influenced by the amount of pollution in the form of aerosol particles, which determine how many cloud droplets form and how large they are. Unfortunately, different numerical models give different answers on whether rain and hail increase or decrease if pollution increases. In this article, we present a new analysis method helping to identify the small‐scale processes which are responsible for the increase or decrease in a specific numerical scheme. We apply it to simulations of thunderstorms and show that the decrease of rain and hail in the numerical model used here is mostly linked to the riming process. Riming is the collision of cloud droplets and frozen particles at temperatures below 0°C, such that the liquid water freezes to the surface of the ice particles and makes them bigger. Less riming occurs when pollution increases, because cloud droplets are smaller. This process is very important because nearly all rain reaching the surface consists of melted ice particles.
    Description: Key Points: Microphysical pathways are constructed by tracking microphysical processes rates and closing the hydrometeor mass budget. More cloud condensation nuclei lead to less surface precipitation and hail, due to smaller cloud drop sizes and reduced riming collection efficiency. Simulations with constant riming collection efficiency reveal two different hail formation pathways.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: HORIZON EUROPE European Research Council http://dx.doi.org/10.13039/100019180
    Description: https://doi.org/10.5445/IR/1000156063
    Keywords: ddc:551.5 ; convective clouds ; hail ; riming ; precipitation ; CCN ; convection‐permitting simulation
    Language: English
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    Aluminum Components in Bridgmanite Coexisting With Corundum and the CF‐Phase With Temperature (2023)
    Details
    Publication Date: 2023-11-02
    Description: Abstract Phase relations in the MgSiO〈sub〉3〈/sub〉–MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 system are investigated at 27 GPa and 2000–2600 K using a multi‐anvil apparatus. The AlAlO〈sub〉3〈/sub〉 content in the bridgmanite increases from 8.6 to 20.0 mol% with increasing temperature from 2000 to 2600 K, while the MgAlO〈sub〉2.5〈/sub〉 content remains nearly constant, that is, 3–4 mol% at these temperatures. Therefore, the presence of an additional Al‐bearing phase suppresses the oxygen vacancy substitution for Al〈sup〉3+〈/sup〉 in bridgmanite. Conversely, significant amounts of the Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 component can be dissolved into the calcium‐ferrite type MgAl〈sub〉2〈/sub〉O〈sub〉4〈/sub〉–Mg〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉–Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 phase (CF‐phase), implying that the CF‐phase likely contains some amount of vacancies. Therefore, the CF‐phase could also be a candidate mineral for transporting volatiles into the lower mantle. Our results, combined with previous studies on Al‐bearing bridgmanite, indicate that, once the Al per formula unit exceeds 0.12 in bridgmanite, the MgAlO〈sub〉2.5〈/sub〉 content remains nearly constant and the AlAlO〈sub〉3〈/sub〉 component becomes dominant.
    Description: Plain Language Summary: Bridgmanite, the most abundant mineral in the Earth's mantle, can contain Al〈sup〉3+〈/sup〉 in the forms of MgAlO〈sub〉2.5〈/sub〉 and AlAlO〈sub〉3〈/sub〉. To constrain the substitution mechanism of Al〈sup〉3+〈/sup〉 in bridgmanite, we investigate the MgAlO〈sub〉2.5〈/sub〉 and AlAlO〈sub〉3〈/sub〉 contents in bridgmanite coexisting with a calcium‐ferrite type phase and corundum at different temperatures. Our results demonstrate that the MgAlO〈sub〉2.5〈/sub〉 content reaches saturation (3–4 mol%) when an additional Al‐bearing phase exists in the system.
    Description: Key Points: The MgAlO〈sub〉2.5〈/sub〉 content in bridgmanite remains constant with temperature when bridgmanite coexists with corundum and the CF‐phase. The MgAlO〈sub〉2.5〈/sub〉 content in bridgmanite reaches a solubility of 3–4 mol% when bridgmanite coexists with an additional Al‐bearing phase. A significant amount of the Al〈sub〉8/3〈/sub〉O〈sub〉4〈/sub〉 component can be dissolved into the CF‐phase.
    Description: HORIZON EUROPE European Research Council http://dx.doi.org/10.13039/100019180
    Description: Japan Society for the Promotion of Science London http://dx.doi.org/10.13039/501100000646
    Description: cooperative research program of the Earthquake Research Institute
    Description: https://doi.org/10.5281/zenodo.7512647
    Keywords: ddc:549 ; Al‐bearing bridgmanite ; Al substitute mechanism ; phase relation ; volatile
    Language: English
    Type: doc-type:article
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    The Linkage of Serial Cyclone Clustering in Western Europe and Weather Regimes in the North Atlantic‐European Region in Boreal Winter (2023)
    Hauser, Seraphine ; Mueller, Sebastian ; Chen, Xiaoyang ; [et al.]
    Details
    Publication Date: 2023-11-02
    Description: Extra‐tropical cyclones are an important source of weather variability in the mid‐latitudes. Multiple occurrences in a short period of time at a particular location are denominated serial cyclone clustering (SCC), and potentially lead to large societal impacts. We investigate the relationship between SCC affecting Western Europe and large‐scale weather regimes (WRs) in the North Atlantic‐European region in boreal winter. We find that SCC in low latitudes (45°N) is predominantly associated with the anticyclonic Greenland Blocking WR. In contrast, SCC in mid and high latitudes (55°N, 65°N) is mostly linked to different cyclonic WRs. Thereby, SCC occurs typically within a well‐established WR that builds up prior to SCC and decays after SCC. Thus, SCC events are closely associated with recurrent, quasi‐stationary and persistent large‐scale flow patterns (WRs). This mutual relationship reveals the potential of WRs in forecasting storm series and associated impacts on sub‐seasonal to seasonal time scales.
    Description: Plain Language Summary: Serial cyclone clustering describes the occurrence of multiple extra‐tropical cyclones within a certain time frame and a spatially restricted region. Since extra‐tropical cyclones can be associated with strong winds and heavy precipitation, multiple occurrences can lead to large cumulative impacts in the affected areas. We analyze the relationship between serial cyclone clustering (SCC) in Western Europe and so‐called weather regimes (WRs) in the North Atlantic‐European region in boreal winter. These regimes describe slow evolving and enduring large‐scale atmospheric circulation patterns. Relationships with certain regime types are identified but depend on the latitude at which the clustered frequency of extra‐tropical cyclones is found. When SCC occurs in low latitudes (45°N), it mostly appears coincident with anticyclonic large‐scale flow patterns. In contrast, SCC in mid and high latitudes (55°N, 65°N) often occurs simultaneously with different cyclonic regimes. We find that periods of SCC occur typically within WR life cycles pointing to the fact that both, the WRs and SCC periods, are interlinked. This relationship may facilitate forecasting storm series and associated impacts on time scales beyond 2 weeks.
    Description: Key Points: A close relationship is found between serial cyclone clustering (SCC) at 5°W and weather regimes (WRs) in the North Atlantic‐European region. SCC in mid and high latitudes (55°N, 65°N) is mainly associated with cyclonic and in low latitudes (45°N) with anticyclonic WR life cycles. Regardless of the selected latitude, SCC occurs mostly during an active regime life cycle and is manifested in a well‐established WR.
    Description: German Research Foundation
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: BMBF ClimXtreme
    Description: https://www.ecmwf.int/en/forecasts/datasets/reanalysis-datasets/era-interim
    Keywords: ddc:551.5 ; serial cyclone clustering ; weather regimes ; atmospheric dynamics ; sub‐seasonal prediction
    Language: English
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  • 100
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    Soil resistivity measurements to evaluate subsoil salinity in rice production systems in the Vietnam Mekong Delta (2023)
    Details
    Publication Date: 2023-11-02
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Rice is a staple crop in the Vietnam Mekong Delta (VMD) in which more than half of Vietnam's rice is produced. However, rice production in the VMD is threatened by increasing saltwater intrusion due to land subsidence and climate change induced sea level rise. Saltwater intrusion into lowland areas through the canal system or capillary rise of saline water from near surface saline water tables may result in salt accumulation in the topsoil. Therefore, it is important to disentangle the two effects and their relative importance to implement appropriate strategies for water and salinity management for adapting rice production systems of the VMD to climate change. Here, we report on the possibility of using geoelectrical methods to evaluate the potential threat of subsoil salinity to rice production. To evaluate the level of subsoil salinity, we measured soil electrical resistivity using an ARES II to a depth of 40 m in a case study comprising five locations in the VMD. Electrical resistivity measurements were calibrated to soil types, which were identified through evaluating 1 m core sections obtained by drilling down to 40 m depth. The relationship between drilling data and soil resistivity was determined by applying clustering and principal component analysis. Resistivity values smaller than 3 Ω m were clearly identified as indicative for a saline water table. The results show a direct link between the depth of the saline water table and the proximity to the sea, but not to the rice production system (single, double, or triple cropping). This study proved for the first time the applicability of the electrical resistivity tomography method for identifying groundwater tables and evaluating subsoil salinity on an agricultural field scale in the VMD.〈/p〉
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Federal Ministry of Education and Research (BMBF, Germany)
    Keywords: ddc:631.4 ; conductivity ; electrical resistivity tomography ; groundwater ; site effect
    Language: English
    Type: doc-type:article
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