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  • 1
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    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2024-06-19
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom Juni 2024 enthält die Themenblöcke: GEOfokus: Die Ur-Ems – ein Fluss legt sich zurück -Vom Ende der Eiszeit zurück in die Zukunft-, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 136
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  • 2
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    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2023-10-16
    Beschreibung: 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).
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 112
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  • 3
    Publikationsdatum: 2023-11-23
    Beschreibung: 〈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〉
    Beschreibung: 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〉
    Beschreibung: 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〉
    Beschreibung: https://doi.org/10.5281/ZENODO.7049722
    Schlagwort(e): ddc:550 ; SIP ; surface ; roughness
    Sprache: Englisch
    Materialart: doc-type:article
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  • 4
    Publikationsdatum: 2023-12-07
    Beschreibung: Publishing data with a DOI (Digital Object Identifier) is becoming increasingly popular, and many researchers are being asked by journals to publish the data underlying the research results described in the article. Where does the data come from and how do I cite it correctly? […] This publication is a translation of the FID GEO article in 〈a href="http://doi.org/10.23689/fidgeo-5688"〉GMIT 90.〈/a〉
    Beschreibung: research
    Schlagwort(e): ddc:550 ; GMIT ; Geowissenschaftliche Mitteilungen
    Sprache: Englisch
    Materialart: doc-type:article , publishedVersion
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  • 5
    Publikationsdatum: 2023-12-07
    Beschreibung: The ORCID is an open alphanumeric identifier used to uniquely identify researchers.In an increasingly connected scientific landscape, the growing number of published research outputs (data, text, software) and new open publishing models pose major challenges for scientific publication management. The repositories available to FID GEO, GEO-LEOe-docs (SUB Goettingen) and GFZ Data Services (GFZ), have long been working with PIDs such as the Digital Object Identifier (DOI ) and the Open Researcher and Contributor iD (ORCID iD ), and recommend the use of the ORCID. This publication is a translation of the FID GEO article in 〈a href="http://doi.org/10.23689/fidgeo-5832"〉GMIT 87.〈/a〉
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: research
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Englisch
    Materialart: doc-type:article , publishedVersion
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  • 6
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    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2024-01-04
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2023 enthält die Themenblöcke: GEOfokus: Dimensionierung und Betrieb von Erdwärmesonden, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 120
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  • 7
    Publikationsdatum: 2023-02-28
    Beschreibung: Im Albvorsprung südlich Regensburg liegen zwischen Störungen der mesozoischen Schichttafel schmale Becken. Während deren Bildung setzte sich ein klastischer Sedimentkomplex in den expandierenden Becken ab, der in das obere Untermiozän-untere Mittelmiozän gestellt wird und in konkav aufgebogener Lagerungsform vorliegt. Die Diskordanz an der Basis der überlagernden Sand- und Geröllschichten wird dem Mittelmiozän zugerechnet und zeigt den Abschluß der tektonischen Beckenbildung. Es wird angenommen, dass die Verbiegung des nach 150° tauchenden, älteren Hemauer Sattels ein Spannungsfeld verursachte und damit senkrecht zu dessen Achse orientierte Dehnungsbrüche und ein konjugiertes Scherkluftsystem erzeugte. Dadurch kam es vermutlich zu den extensionalen Beckenbildungen, deren Längsachsen an den Maxima der Kluftrichtungen und Bruchflächen orientiert waren. Dieses System wurde von der in Mitteleuropa heute ~140° streichenden horizontalen Schubspannung (Prinz & Strauss 2018) überlagert. Darüber hinaus können beide von Peterek et al. (1997) über Paläostress-Analysen für den Zeitraum des (beginnenden) Neogens dargestellten Extensionsregimes zur Erklärung der tektonischen Beckenbildungen im hier untersuchten Gebiet beitragen. Die Ergebnisse stellen Grundlagen für Baugrunduntersuchungen im Bereich Regensburg-Süd und Bad Abbach dar.
    Beschreibung: research
    Schlagwort(e): ddc:550 ; Miozäne Dehnungsbecken ; Tertiär ; Regensburg-Süd ; Bad Abbach
    Sprache: Deutsch
    Materialart: doc-type:article
    Format: 19
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  • 8
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2023-07-04
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom Juni 2022 enthält die Themenblöcke: GEOfokus:Mariengraben - Am Puls der tiefen Erde, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 124
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  • 9
    Publikationsdatum: 2023-07-21
    Beschreibung: Oceanic circulation and mass‐field variability play important roles in exciting Earth's wobbles and length‐of‐day changes (ΔΛ), on time scales from days to several years. Modern descriptions of these effects employ oceanic angular momentum (OAM) series from numerical forward models or ocean state estimates, but nothing is known about how ocean reanalyses with sequential data assimilation (DA) would fare in that context. Here, we compute daily OAM series from three 1/4° global ocean reanalyses that are based on the same hydrodynamic core and input data (e.g., altimetry, Argo) but different DA schemes. Comparisons are carried out (a) among the reanalyses, (b) with an established ocean state estimate, and (c) with Earth rotation data, all focusing on the period 2006–2015. The reanalyses generally provide credible OAM estimates across a range of frequencies, although differences in amplitude spectra indicate a sensitivity to the adopted DA scheme. For periods less than 120 days, the reanalysis‐based OAM series explain ∼40%–50% and ∼30%–40% of the atmosphere‐corrected equatorial and axial geodetic excitation, similar to what is achieved with the state estimate. We find mixed performance of the reanalyses in seasonal excitation budgets, with some questionable mean ocean mass changes affecting the annual cycle in ΔΛ. Modeled excitations at interannual frequencies are more uncertain compared to OAM series from the state estimate and show hints of DA artifacts in one case. If users are to choose any of the tested reanalyses for rotation research, our study points to the Ocean Reanalysis System 5 as the most sensible choice.
    Beschreibung: Key Points: We evaluate three ocean reanalyses for their skill in explaining Earth rotation variations on different time scales from 2006 to 2015. For periods 〈120 days, reanalyses explain 40%–50% of atmosphere‐reduced polar motion excitation variance, similar to an ocean state estimate. Reanalyses show mixed skill in seasonal excitation budgets and, in one case, hints of data assimilation artifacts at interannual periods.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://resources.marine.copernicus.eu/product-detail/GLOBAL_REANALYSIS_PHY_001_031/INFORMATION
    Beschreibung: https://isdc.gfz-potsdam.de/ggfc-oceans/oam/
    Beschreibung: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ngdc.mgg.dem:316
    Beschreibung: https://podaac-tools.jpl.nasa.gov/drive/files/GeodeticsGravity/tellus/L3/mascon/RL06/JPL/v02/CRI/netcdf
    Beschreibung: https://keof.jpl.nasa.gov/combinations/
    Schlagwort(e): ddc:550 ; Earth rotation ; ocean angular momentum ; ocean reanalysis ; data assimilation
    Sprache: Englisch
    Materialart: doc-type:article
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  • 10
    Publikationsdatum: 2023-07-21
    Beschreibung: 〈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"〉Benthic oxygen dynamics and the exchange of oxygen and other solutes across the sediment‐water interface play a key role for the oxygen budget of many limnic and shallow marine systems. The sediment‐water fluxes are largely determined by two factors: sediment biogeochemistry and the thickness of the diffusive boundary layer that is determined by near‐bottom turbulence. Here, we present a fully coupled benthic‐pelagic modeling system that takes these processes and their interaction into account, focusing especially on the modulation of the sediment‐water fluxes by the effects of near‐bottom turbulence and stratification. We discuss the special numerical methods required to guarantee positivity and mass conservation across the sediment‐water interface in the presence of rapid element transformation, and apply this modeling system to a number of idealized scenarios. Our process‐oriented simulations show that near‐bottom turbulence provides a crucial control on the sediment‐water fluxes, the oxygen penetration depth, and the re‐oxidation of reduced compounds diffusing upward from the deeper benthic layers especially on time scales of a few days, characterizing oceanic tides, internal seiching motions in lakes, and mesoscale atmospheric variability. Our results also show that the response of benthic‐pelagic fluxes to rapid changes in the forcing conditions (e.g., storm events) can only be understood with a fully coupled modeling approach.〈/p〉
    Beschreibung: Plain Language Summary: Oxygen is one of the most relevant ecosystem parameters in marine systems and in lakes. In shallow systems, the overall oxygen budget is often controlled by the sedimentary oxygen demand, and it is therefore crucial to account for the exchange of oxygen and other solutes between the sediment and the water column. In this, context, a thin (millimeter‐scale) “diffusive sublayer,” located immediately above the sediment surface, is known to play an especially important role as it may form a bottleneck for the solute exchange. As the thickness of this sublayer is controlled by hydrodynamic processes, sediment‐water fluxes are affected by complex feedbacks between physical and biogeochemical processes. Here, we describe a fully coupled numerical modeling system that takes these feedback mechanisms into account, including advanced numerical methods guaranteeing that the total mass of all solutes is conserved (even if these are transformed) and that their concentrations do not become negative. Using a series of idealized examples, it is shown that near‐bottom hydrodynamic processes have an important impact on the sediment‐water fluxes, the depth to which oxygen penetrates into the upper sediment layers, and the re‐oxidation of reduced chemical compounds in the sediments. These feedbacks are particularly important for processes with time scales of a few days, like ocean tides, internal oscillations in lakes, and short‐term atmospheric disturbances (e.g., storm events).〈/p〉
    Beschreibung: Key Points: First fully coupled benthic‐pelagic modeling system accounting for the effects of near‐bottom turbulence on sediment‐water solute fluxes. Hydrodynamic effects control benthic biogeochemistry and fluxes especially on time scales of a few days, and during extreme events. New numerical methods that guarantee mass conservation and positivity across the sediment‐water interface.
    Beschreibung: Leibniz Association
    Beschreibung: German Research Foundation
    Beschreibung: Swiss National Science Foundation
    Beschreibung: UK Natural Environment Research Council
    Beschreibung: Department for Environment Food and Rural Affairs
    Beschreibung: https://gotm.net/
    Beschreibung: https://github.com/fabm-model
    Beschreibung: https://doi.org/10.5281/zenodo.7950383
    Beschreibung: https://doi.org/10.5281/zenodo.7950866
    Schlagwort(e): ddc:550 ; sediment-water fluxes ; benthic biogeochemistry ; numerical modeling
    Sprache: Englisch
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  • 11
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    In:  ARGE GMIT
    Publikationsdatum: 2023-03-27
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2022 enthält die Themenblöcke: GEOfokus: Zwischen Scylla und Charybdis - Die Rolle von Recycling und Primärrohstoffen am Beispiel von Kupfer und Lithium, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 124
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  • 12
    Publikationsdatum: 2023-06-12
    Beschreibung: Soils and landscapes are bridges of space and time, as they simultaneously and authentically show essential aspects that were previously separated by time and space (such as cultural and activity-related aspects from past and present) to the trained observer - albeit only in excerpts. Therefore, this article presents a series of impact indicators for soil changes, starting with extreme (anthropogenic) interventions and ending with equally extreme ("natural") events. An essential difference to specifically planning-relevant or human ecological concepts, which, for example, specify land use/load categories, is that the following impact indicators perceive soils as a phenomenon in themselves and do not define them through attributed functions. Particular attention is focused on their changeability and vital development potential, as well as on their property as a sphere of penetration of living and material things, with emphasis on the noetic effect. The intervention or event spaces on the earth's surface can be differentiated quantitatively through the type, strength, and duration of the phenomena. The intensity of all processes can be described by amplitude (the strength of the interventions/events) and frequency (the repetition rate of the interventions/events) and can be specifically identified and quantified by, for example, material inputs or outputs per unit of time. For the first time, there would be a system for measuring the ecological quality of anthropogenic land use, which could serve as an "alert system for the external technological culture," and could help us become aware of our "inner" culture.
    Beschreibung: research
    Schlagwort(e): ddc:550 ; Boden ; Landschaft ; Bodendegeneration ; Deutschland ; Anthropogene Bodenveränderung
    Sprache: Deutsch
    Materialart: doc-type:article
    Format: 9
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  • 13
    Publikationsdatum: 2023-07-18
    Beschreibung: Methane seeps are typified by the formation of authigenic carbonates, many of which exhibit corrosion surfaces and secondary porosity believed to be caused by microbial carbonate dissolution. Aerobic methane oxidation and sulfur oxidation are two processes capable of inducing carbonate corrosion at methane seeps. Although the potential of aerobic methanotrophy to dissolve carbonate was confirmed in laboratory experiments, this process has not been studied in the environment to date. Here, we report on a carbonate corrosion experiment carried out in the REGAB Pockmark, Gabon‐Congo‐Angola passive margin, in which marble cubes were deployed for 2.5 years at two sites (CAB‐B and CAB‐C) with apparent active methane seepage and one site (CAB‐D) without methane seepage. Marble cubes exposed to active seepage (experiment CAB‐C) were found to be affected by a new type of microbioerosion. Based on 16〈italic toggle="no"〉S r〈/italic〉RNA gene analysis, the biofilms adhering to the bioeroded marble mostly consisted of aerobic methanotrophic bacteria, predominantly belonging to the uncultured Hyd24‐01 clade. The presence of abundant 〈sup〉13〈/sup〉C‐depleted lipid biomarkers including fatty acids (〈italic toggle="no"〉n〈/italic〉‐C〈sub〉16:1ω8c〈/sub〉, 〈italic toggle="no"〉n〈/italic〉‐C〈sub〉18:1ω8c〈/sub〉, 〈italic toggle="no"〉n〈/italic〉‐C〈sub〉16:1ω5t〈/sub〉), various 4‐mono‐ and 4,4‐dimethyl sterols, and diplopterol agrees with the dominance of aerobic methanotrophs in the CAB‐C biofilms. Among the lipids of aerobic methanotrophs, the uncommon 4α‐methylcholest‐8(14)‐en‐3β,25‐diol is interpreted to be a specific biomarker for the Hyd24‐01 clade. The combination of textural, genetic, and organic geochemical evidence suggests that aerobic methanotrophs are the main drivers of carbonate dissolution observed in the CAB‐C experiment at the REGAB pockmark.〈/p〉
    Beschreibung: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Schlagwort(e): ddc:550 ; carbonate ; corrosion ; lipid biomarker ; methane seep ; methanotrophic bacteria ; microbioerosion
    Sprache: Englisch
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  • 14
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    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2024-04-05
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2024 enthält die Themenblöcke: GEOfokus: Geoparks in Deutschland – Modellregionen nachhaltiger Entwicklung, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 112
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  • 15
    Publikationsdatum: 2024-04-09
    Beschreibung: thesis
    Schlagwort(e): ddc:550 ; GEOMIN ; Deutsche Geologische Gesellschaft – Geologische Vereinigung ; Deutsche Mineralogische Gesellschaft
    Sprache: Englisch
    Materialart: doc-type:bookPart , publishedVersion
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  • 16
    Publikationsdatum: 2024-05-08
    Beschreibung: [...] ROR stands for Research Organization Registry and is an open registry for research organizations. The registry is developed and operated as a joint initiative of the California Digital Library, Crossref and DataCite. ROR already references more than 103,000 organizations, ranging from universities and extramural research institutions to government agencies, research funders and government departments. [...] This publication is a translation of the FID GEO article in 〈a href="http://doi.org/10.23689/fidgeo-5750"〉GMIT 91.〈/a〉
    Beschreibung: research
    Schlagwort(e): ddc:550 ; GMIT ; Geowissenschaftliche Mitteilungen
    Sprache: Englisch
    Materialart: doc-type:article , publishedVersion
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  • 17
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    Unbekannt
    Reimer, Berlin
    In:  Heraugeberexemplar
    Publikationsdatum: 2022-01-12
    Beschreibung: Mit dieser Festschrift soll das wissenschaftliche und akademische Wirken von MAX RICHTER geehrt werden. Anläßlich seines 65. Geburtstages widmeten ihm seine Schüler bereits eine Festschrift, doch setzte der Jubilar seine Lehre und Forschung bis zum heutigen 80. Geburtstag in körperlicher und geistiger Frische fort. Entsprechend der vorrangigen Forschungstätigkeit von MAX RICHTER erhielt die Festschrift als Rahmenthema "Geologie junger Orogene". Über 50 Jahre geologisches Arbeiten in den Alpen, aber auch im gesamten Mittelmeerraum und in Nordamerika erbrachten eine Fülle von Publikationen des Jubilars mit richtungsweisenden Erkenntnissen.
    Beschreibung: commemorativepublication
    Beschreibung: DFG, SUB Göttingen
    Schlagwort(e): 551 ; Orogene als festländische Erdkrustentypen {Tektonik} ; Festschriften {Geologische Wissenschaften} ; Junges Faltengebirge ; Geologie ; FID-GEO-DE-7
    Sprache: Deutsch
    Materialart: map
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  • 18
    Publikationsdatum: 2023-09-13
    Beschreibung: 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.
    Beschreibung: 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.
    Beschreibung: 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.
    Beschreibung: Bundesministerium für Bildung, Wissenschaft und Forschung http://dx.doi.org/10.13039/501100013699
    Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Beschreibung: Helmholtz Centre Potsdam ‐ Deutsches GeoForschungsZentrum GFZ
    Beschreibung: RI Fabrice Cotton
    Beschreibung: Federal Company for radioactive waste disposal
    Beschreibung: https://github.com/MorZieg/FAST_Calibration
    Schlagwort(e): ddc:550 ; geomechanics ; uncertainties ; stress state ; modeling ; Bayes
    Sprache: Englisch
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  • 19
    Publikationsdatum: 2023-01-14
    Beschreibung: Spaceborne impact ionization mass spectrometers, such as the Cosmic Dust Analyzer on board the past Cassini spacecraft or the SUrface Dust Analyzer being built for NASA's upcoming Europa Clipper mission, are of crucial importance for the exploration of icy moons in the Solar System, such as Saturn's moon Enceladus or Jupiter's moon Europa. For the interpretation of data produced by these instruments, analogue experiments on Earth are essential. To date, thousands of laboratory mass spectra have been recorded with an analogue experiment for impact ionization mass spectrometers. Simulation of mass spectra of ice grains in space is achieved by a Laser Induced Liquid Beam Ion Desorption (LILBID) approach. The desorbed cations or anions are analyzed in a time‐of‐flight mass spectrometer. The amount of unstructured raw data is increasingly challenging to sort, process, interpret and compare with data from space. Thus far this has been achieved manually for individual mass spectra because no database containing the recorded reference spectra was available. Here we describe the development of a comprehensive, extendable database containing cation and anion mass spectra from the laboratory LILBID facility. The database is based on a Relational Database Management System with a web server interface and enables filtering of the laboratory data using a wide range of parameters. The mass spectra can be compared not only with data from past and future space missions but also mass spectral data generated by other, terrestrial, techniques. The validated and approved subset of the database is available for general public (https://lilbid-db.planet.fu-berlin.de).
    Beschreibung: Plain Language Summary: Thousands of laboratory mass spectra, each with an individual set of experimental parameters, have been recorded so far using a facility situated at Freie Universität Berlin, Germany. The mass spectra help analyze and interpret data returned from spacecraft in the vicinity of icy moons in the Solar System. The unstructured laboratory data is increasingly challenging to sort and compare to the data from space. We developed an extendable database containing the laboratory data. The database is available for general public and allows filtering the stored data for a wide range of experimental parameters and, in turn, significantly improves analysis of data not only from past space missions but also future missions in particular.
    Beschreibung: Key Points: We describe the development of a comprehensive spectral database containing laboratory analogue data for spaceborne mass spectrometers. The database is based on a Relational Database Management System with a web interface and accessible for community use. Filtering the laboratory data using a wide range of experimental parameters allows a straightforward analysis of returned flight data.
    Beschreibung: EC, Horizon 2020 Framework Programme (H2020) http://dx.doi.org/10.13039/100010661
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.org/10.5281/zenodo.6863855
    Beschreibung: https://sbnarchive.psi.edu/pds3/cassini/cda/COCDA_0007.tar.gz
    Schlagwort(e): ddc:550 ; mass spectral database ; analogue experiments ; ice grains ; ocean worlds ; SUDA ; ENIA ; LILBID ; TOF‐MS
    Sprache: Englisch
    Materialart: doc-type:article
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  • 20
    Publikationsdatum: 2023-03-15
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; InSAR
    Sprache: Englisch
    Materialart: doc-type:conferenceObject
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  • 21
    Publikationsdatum: 2023-08-29
    Beschreibung: conference
    Schlagwort(e): ddc:550 ; GEOMIN ; Deutsche Geologische Gesellschaft – Geologische Vereinigung ; Deutsche Mineralogische Gesellschaft ; Clathrate hydrate
    Sprache: Englisch
    Materialart: doc-type:book , publishedVersion
    Format: 440
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  • 22
    Publikationsdatum: 2022-12-08
    Beschreibung: Während der Corona-Pandemie schrieb der Schüler Pascal Schmitt mit Unterstützung des Vereins Wiechert'sche Erdbebenwarte Göttingen e.V.  im "Homeschooling" eine Facharbeit über die Auswertung seismischer Daten. Darin werden einige Daten eines Nah- und eines Fernbebens analysiert, die in Göttingen an der modernen Station GTTG (STS-2-Seismometer) und der historischen Station GTT (Wiechert-Seismographen) registriert wurden - nah und fern, neu und alt werden miteinander verglichen.
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: research
    Schlagwort(e): ddc:551.22 ; ddc:550 ; GTT ; GTTG ; STS-2-Seismometer ; Wiechert-Seismographen ; Nahbeben ; Vergleiche
    Sprache: Deutsch
    Materialart: doc-type:article
    Format: 7
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  • 23
    Publikationsdatum: 2022-12-08
    Beschreibung: Aus Anlass des 100. Jahrestages der Gründung der Deutschen Geophysikalischen Gesellschaft im Jahre 1922 in Leipzig erschien 2019 im Verlag Edition am Gutenbergplatz Leipzig das Taschenbuch „Wiechert, Mintrop & Co. – Die 24 Gründungsväter der Deutschen Geophysikalischen Gesellschaft“ von Franz Jacobs und Michael Börngen (s. gleichlautenden Archivbeitrag in DGG-Mitteilungen, 1/2019: 36–37 sowie das anbei dargestellte Titelblatt des Buches). Die damalige Präsidentin und heutige Vize-Präsidentin der DGG, Heidrun Kopp, hat mit einem Geleitwort beigetragen. Das Buch kann über den Buchhandel unter ISBN 978-3-95922-107-8 bestellt werden. Der folgende Artikel erinnert an die Meteorologin Luise Lammert, Schriftführerin der Versammlung, auf der der Gründungsbeschluss gefasst wurde.
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: research
    Schlagwort(e): ddc:550 ; Luise Charlotte Lammert
    Sprache: Deutsch
    Materialart: doc-type:article
    Format: 7
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  • 24
    Publikationsdatum: 2022-12-09
    Beschreibung: Leben und Werk des deutschen Geophysikers und Meteorologen Friedrich Bidlingmaier. In den Jahren 1901-03 nahm er als Physiker an der deutschen Südpolexpedition unter E. von Drygalski teil, dessen Ergebnisse zur Erforschung des Erdmagnetismus beitrugen. Er erfand den Doppelkompass zur Messung der horizontalen geomagnetischen Intensität. Cape Bidlingmaier an der Nordküste von Heard Island im südlichen Indischen Ozean trägt seinen Namen.
    Beschreibung: research
    Schlagwort(e): ddc:550 ; Geomagnetismus ; Observatorium
    Sprache: Deutsch
    Materialart: doc-type:article
    Format: 5
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  • 25
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2023-01-17
    Beschreibung: It is generally agreed that the resolution of a regular quadrilateral mesh is the side length of quadrilateral cells. There is less agreement on the resolution of triangular meshes, exacerbated by the fact that the numbers of edges or cells on triangular meshes are approximately three or two times larger than that of vertices. However, the geometrical resolution of triangular meshes, that is, maximum wavenumbers or smallest wavelengths that can be represented on such meshes, is a well defined quantity, known from solid state physics. These wavenumbers are related to a smallest common mesh cell (primitive unit cell), and the set of mesh translations that map it into itself. They do not depend on whether discrete degrees of freedom are placed on vertices, cells or edges. For equilateral triangles the smallest wavelength equals twice the triangle height. Resolutions of quadrilateral and triangular meshes approximately agree if they have the same numbers of vertices.
    Beschreibung: Plain Language Summary: Some models used in climate studies are formulated on triangular computational meshes. We discuss how to determine the smallest scales that are resolved on such meshes. They are referred to as a mesh resolution. The notion of mesh resolution is commonly used to relate climate model results simulated on different meshes.
    Beschreibung: Key Points: Geometrical resolution of an equilateral triangular mesh is defined by the height of its triangles. Quadrilateral and triangular meshes with the same number of vertices have approximately the same resolution.
    Beschreibung: Collaborative Research Centre
    Beschreibung: German Research Foundation
    Schlagwort(e): ddc:550 ; triangular meshes ; resolved wavenumbers
    Sprache: Englisch
    Materialart: doc-type:article
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  • 26
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2023-01-09
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2022 enthält die Themenblöcke: GEOfokus: Klimagerechte Geowissenschaften Glaubwürdigkeit und Vorbild, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550 ; GMIT
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 132
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  • 27
    Publikationsdatum: 2022-06-26
    Beschreibung: Efficient compositional models are required to simulate underground gas storage in porous formations where, for example, gas quality (such as purity) and loss of gas due to dissolution are of interest. We first extend the concept of vertical equilibrium (VE) to compositional flow, and derive a compositional VE model by vertical integration. Second, we present a hybrid model that couples the efficient compositional VE model to a compositional full‐dimensional model. Subdomains, where the compositional VE model is valid, are identified during simulation based on a VE criterion that compares the vertical profiles of relative permeability at equilibrium to the ones simulated by the full‐dimensional model. We demonstrate the applicability of the hybrid model by simulating hydrogen storage in a radially symmetric, heterogeneous porous aquifer. The hybrid model shows excellent adaptivity over space and time for different permeability values in the heterogeneous region, and compares well to the full‐dimensional model while being computationally efficient, resulting in a runtime of roughly one‐third of the full‐dimensional model. Based on the results, we assume that for larger simulation scales, the efficiency of this new model will increase even more.
    Beschreibung: Key Points: A compositional vertical equilibrium model is coupled to its full‐dimensional counterpart. A criterion is developed to adaptively identify and assign regions where the vertical equilibrium model is applicable during simulation. A test case of hydrogen storage in a heterogeneous porous aquifer demonstrates efficiency and accuracy of the hybrid model.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://git.iws.uni-stuttgart.de/dumux-pub/Becker2021b.git
    Schlagwort(e): ddc:551.49 ; ddc:550
    Sprache: Englisch
    Materialart: doc-type:article
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  • 28
    Publikationsdatum: 2022-06-22
    Beschreibung: Basal melting of marine‐terminating glaciers, through its impact on the forces that control the flow of the glaciers, is one of the major factors determining sea level rise in a world of global warming. Detailed quantitative understanding of dynamic and thermodynamic processes in melt‐water plumes underneath the ice‐ocean interface is essential for calculating the subglacial melt rate. The aim of this study is therefore to develop a numerical model of high spatial and process resolution to consistently reproduce the transports of heat and salt from the ambient water across the plume into the glacial ice. Based on boundary layer relations for momentum and tracers, stationary analytical solutions for the vertical structure of subglacial non‐rotational plumes are derived, including entrainment at the plume base. These solutions are used to develop and test convergent numerical formulations for the momentum and tracer fluxes across the ice‐ocean interface. After implementation of these formulations into a water‐column model coupled to a second‐moment turbulence closure model, simulations of a transient rotational subglacial plume are performed. The simulated entrainment rate of ambient water entering the plume at its base is compared to existing entrainment parameterizations based on bulk properties of the plume. A sensitivity study with variations of interfacial slope, interfacial roughness and ambient water temperature reveals substantial performance differences between these bulk formulations. An existing entrainment parameterization based on the Froude number and the Ekman number proves to have the highest predictive skill. Recalibration to subglacial plumes using a variable drag coefficient further improves its performance.
    Beschreibung: Plain Language Summary: In a world of global warming, the melting of glaciers terminating as floating ice tongues into the oceans of Arctic and Antarctic regions allows those glaciers to flow faster and hence to make a considerable contribution to global mean sea‐level rise. Underneath the ice‐ocean interface, turbulent currents of the order of 10 m thickness (so‐called plumes) develop that transport the melt water from the grounding line where the glacier enters the ocean toward the calving front that marks the seaward end of the glacier. At its base, ambient relatively warm and salty ocean water is mixed into the plumes and is vertically transported toward the ice‐ocean interface, where the melting is increased due to the additional heat supply. Understanding these processes is essential for their incorporation into computer models for the prediction of such melt processes. In this study, an accurate simulation model for the water column is constructed that is able to consistently reproduce these processes. The algorithms developed here are proven to provide reliable results also for models with only a few grid points across the plume and can therefore be implemented into climate models with surface‐following coordinates to more accurately simulate future scenarios of sea level rise.
    Beschreibung: Key Points: A vertically resolving model with second‐moment turbulence closure has been constructed for subglacial plumes. Convergent numerical formulations for the ocean‐to‐ice fluxes of momentum, freshwater and heat have been derived from an analytical model. Model results are consistent with bulk parameterizations for the entrainment of ambient water.
    Beschreibung: Bundesministerium für Bildung und Forschung (BMBF) http://dx.doi.org/10.13039/501100002347
    Beschreibung: https://doi.org/10.5281/zenodo.6203838
    Schlagwort(e): ddc:550
    Sprache: Englisch
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  • 29
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2022-09-14
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom September 2022 enthält die Themenblöcke: GEOfokus: Rohstoffe für die deutsche Energiewende, GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 100
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  • 30
    Publikationsdatum: 2022-10-17
    Beschreibung: Hydrogen is a promising alternative to carbon based energy carriers and may be stored in large quantities in subsurface storage deposits. This work assesses the impact of static (density and phase equilibria) and dynamic (viscosity and diffusion coefficients) properties on the pressure field during the injection and extraction of hydrogen in the porous subsurface. In a first step, we derive transport properties for water, hydrogen and their mixture using the Perturbed‐Chain Statistical Associating Fluid Theory equation of state in combination with an entropy scaling approach and compare model predictions to alternative models from the literature. Our model compares excellently to experimental transport coefficients and models from literature with a higher number of adjustable parameters, such as GERG2008, and shows a clear improvement over empirical correlations for transport coefficients of hydrogen. In a second step, we determine the effect of further model reduction by comparing our against a much simpler model applying empirical transport coefficients from the literature. For this purpose, hydrogen is periodically injected into and extracted out of a dome‐shaped porous aquifer under a caprock. Our results show that density and viscosity of hydrogen have the highest impact on the pressure field, and that a thermodynamic model like the new model presented here is essential for modeling the storage aquifer, while keeping the number of coefficients at a minimum. In diffusion‐dominated settings such as the diffusion of hydrogen through the caprock, our developed diffusion coefficients show a much improved dependence on temperature and pressure, leading to a more accurate approximation of the diffusive fluxes.
    Beschreibung: Key Points: We model the phase behavior of pure hydrogen and the binary hydrogen‐water mixture using the Perturbed‐Chain Statistical Associating Fluid Theory equation of state. New entropy scaling relations for the transport properties of hydrogen and water and diffusion coefficients of their mixture are derived. The impact of the newly derived fluid properties is analyzed for a scenario of hydrogen storage in a porous aquifer.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://git.iws.uni-stuttgart.de/dumux-pub/sauerborn2020a
    Schlagwort(e): ddc:550
    Sprache: Englisch
    Materialart: doc-type:article
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  • 31
    Publikationsdatum: 2022-08-05
    Beschreibung: Vlasov solvers that operate on a phase‐space grid are highly accurate but also numerically demanding. Coarse velocity space resolutions, which are largely unproblematic in particle‐in‐cell (PIC) simulations, can lead to numerical heating or oscillations in continuum Vlasov methods. To address this issue, we present a new dual Vlasov solver which is based on an established positivity preserving advection scheme for the update of the distribution function and an energy conserving partial differential equation solver for the kinetic update of mean velocity and temperature. The solvers work together via moment fitting during which the maximum entropy part of the distribution function is replaced by the solution from the partial differential equation solver. This numerical scheme makes continuum Vlasov methods competitive with PIC methods concerning computational cost and enables us to model large scale reconnection in Earth's magnetosphere with a fully kinetic continuum method. The simulation results agree well with measurements by the MMS spacecraft.
    Beschreibung: Key Points: A moment fitting continuum Vlasov solver is presented that preserves positivity of the distribution function and conserves total energy. The method behaves well at low velocity space resolutions, making it competitive with PIC methods concerning computational cost. There is good agreement of the simulations with measurements of magnetic reconnection by the MMS spacecraft.
    Beschreibung: Helmholtz Association (亥姆霍兹联合会致力) http://dx.doi.org/10.13039/501100009318
    Beschreibung: https://vlasov.tp1.ruhr-uni-bochum.de/data/paper-JGR-2021
    Schlagwort(e): ddc:550 ; ddc:538.7
    Sprache: Englisch
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  • 32
    Publikationsdatum: 2022-10-05
    Beschreibung: In recent years, Spatial Markov Models have gained popularity in simulating solute transport in heterogeneous formations. They describe the transition times of particles between equidistant observation planes by statistical distributions, assuming correlation of the transit times of individual particles between subsequent steps. By this, the approach naturally captures preasymptotic solute dispersion. In this study, we analyze Spatial Markov Models assuming bivariate log‐normal distributions of the particle slowness (i.e., the inverse velocity) in subsequent transitions. The model is fully parameterized by the mean Eulerian velocity, the variance of the log‐slowness, and the correlation coefficient of log‐slowness in subsequent steps. We derive closed‐form expressions for distance‐dependent ensemble dispersion, which is defined in terms of the second‐central moments of the solute breakthrough curves. We relate the coefficients to the properties of the underlying log‐hydraulic conductivity field assuming second‐order stationarity. The results are consistent with linear stochastic theory in the limit of small log‐conductivity variances, while the approach naturally extends to high‐variance cases. We demonstrate the validity of the approach by comparison to three‐dimensional particle‐tracking simulations of advective transport in heterogeneous media with isotropic, exponential correlation structure for log‐conductivity variances up to five. This study contributes to relating solute dispersion to metrics of the porous‐medium structure in cases of strong heterogeneity.
    Beschreibung: Key Points: We derive closed‐form expressions of ensemble dispersion in the spatial‐Markov framework of solute transport. The expressions are consistent with linear theory in the limit of small log‐conductivity variances, but extend to high‐variance cases. Comparison to particle‐tracking simulations of advective transport in 3‐D heterogeneous domains show excellent agreement.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: https://doi.org/10.5281/zenodo.6554308
    Beschreibung: https://www.hsl.rl.ac.uk/catalogue/hsl_mi20.html
    Schlagwort(e): ddc:550
    Sprache: Englisch
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  • 33
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2022-06-27
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2022 enthält die Themenblöcke: GEOfokus: (Archäometrie in Deutschland), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 104
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  • 34
    facet.materialart.
    Unbekannt
    ARGE GMIT, Bonn
    Publikationsdatum: 2022-06-27
    Beschreibung: Die Ausgabe der Geowissenschaftlichen Mitteilungen vom März 2022 enthält die Themenblöcke: GEOfokus: Die marine Seismik der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), GEOaktiv (Wirtschaft, Beruf, Forschung und Lehre), GEOlobby (Gesellschaften, Verbände, Institutionen), GEOreport (Geowissenschaftliche Öffentlichkeitsarbeit, Tagungsberichte, Ausstellungen, Exkursionen, Publikationen), GEOszene (Würdigungen, Nachrufe).
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: journal
    Schlagwort(e): ddc:550
    Sprache: Deutsch
    Materialart: doc-type:book , publishedVersion
    Format: 116
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  • 35
    Publikationsdatum: 2022-06-16
    Beschreibung: Atmospheric delay corrections for satellite altimetry measurements are essential for deriving highly accurate sea surface heights and reliable global mean sea level (GMSL) trend estimates. A commonly used method to correct for ionospheric path delays are the usage of GNSS‐based Global Ionospheric Maps (GIM). The different orbit heights of GNSS and altimeter satellites require an adaption of GIM corrections to account for free electrons in the Earth plasmasphere. This study shows that the widely used scaling approach based on the International Reference Ionosphere (IRI) is not able to accurately scale the GIM models. The impact of neglecting the plasmaspheric part of the atmosphere strongly correlates with the solar activity of about 11 years. This manifests itself as trend errors in global GMSL. For the Jason period (2002–2021) a trend error of 0.17 mm/year can be shown, which is even larger for smaller periods (e.g., 1.0 mm/year for Jason‐1 lifetime). The application of an additional constant scaling factor of 0.886 can reduce the trend differences to below 0.05 mm/year.
    Beschreibung: Plain Language Summary: Global mean sea level (GMSL) rise is an important indicator for climate change. To precisely measure this quantity that is only in the order of about 3 mm/year, satellite altimeters are used. Their observations have to be corrected for influences in the Earth atmosphere. This study shows deficiencies in one commonly used correction data set. These corrections, based on observations from the Global Navigation Satellite Systems (GNSS) are not accounting for the higher part of the atmosphere, the plasmasphere. Neglecting this influence derives systematic errors with a 11 years cycle that impacts the estimation of GMSL by up to 1 mm/year, depending on the period under investigation. It is recommended to apply an additional scaling of the available corrections in order to reduce the trend error to below 0.05 mm/year.
    Beschreibung: Key Points: Global Ionospheric Map corrections in altimetry Sensor Geophysical Data Records are not fully scaled to account for plasmaspheric electron content. Neglecting the plasmaspheric effect leads to trends of up to 1 mm/year in Global mean sea level estimates. The additional application of a scale factor improves the consistency in trend with respect to dual‐frequency satellite altimetry data.
    Beschreibung: https://podaac.jpl.nasa.gov/
    Beschreibung: https://www.aviso.altimetry.fr/
    Beschreibung: https://openadb.dgfi.tum.de/en/products/vertical-total-electron-content/
    Schlagwort(e): ddc:538.767 ; ddc:550
    Sprache: Englisch
    Materialart: doc-type:article
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  • 36
    Publikationsdatum: 2022-07-26
    Beschreibung: Im Steinbruch der Firma Balz (Pappenheim) wurde ein Intervall von 18 m Mächtigkeit im Bereich der Unteren Mergelplatte und der Oberen Mergelplatte (Grenzbereich Malm Delta 1-3) der Treuchtlingen Formation untersucht. Die Schichtfolge (16 Bänke; Schichten) kann über mehrere 10-er Kilometer in der Südlichen Frankenalb korreliert werden. Die Bänke sind durch deutliche »Hauptfugen« voneinander getrennt und zeigen oft auch schwach ausgebildete Bank-interne »Nebenfugen«. Die mikrofazielle Analyse wurde anhand von 22 Proben mittels petrographischer Dünnschliffe und röntgenographischer-Analysen zur Ermittlung der tonmineralogischen Zusammensetzung der Nichtkarbonate durchgeführt. Die Bänke bauen sich aus Horizonten verschiedener Partikelkalke (Mikrofazies-Typen) mit charakteristischen Karbonatgehalten auf. Matrix-reiche Wackestones (92-96% Karbonatgehalt), Partikel-reiche Packstones und mikrobielle Bindstones (94-98%) wechseln sich in vertikaler Folge ab. Eingeschaltete Mergel sind entsprechend ihres Anteils an Nichtkarbonaten unterschiedlich ausgebildet. Die Partikelkalke zeigen wechselnde Matrix-Gehalte und Mächtigkeiten von Zentimetern bis Dezimetern innerhalb der Bänke. Sie spiegeln einen stetigen Wechsel der Wasserenergie von gering bis mäßig im Ablagerungsraum wider. Dünne Schalen planktonischer Bivalven (Filamente) wurden zu Zeiten erhöhter Wasserenergie aus entfernten, südlichen Meeresbereichen eingeschwemmt. Mikrobielle Lagen deuten auf eine Fixierung von vorher abgelagerten Sedimenten. Mikrobielle Aktivität führte zu dünnen, mikrobiellen Sedimentlagen, zu rundlichen Onkoiden mit mikritischen Kernen und zur Bildung von länglichen Filament-Onkoiden mit dünnen, langen Filamenten als Kern. Kleine domförmige mikrobielle »Stromatolithe«, Zusammenwachen von Tubiphyten und Serpuliden in kleinen Clustern stellen kleine riffogene Strukturen dar, die lokal am Meeresbodens wachsen konnten, der nur ein geringes Relief von Zentimeter bis Dezimeter Höhe aufgewiesen hat. Röntgenographisch, tonmineralogische Untersuchen zeigen vier Zonen unterschiedlicher Zusammensetzung der Tonmineral-Vergesellschaftung. Eine basale Mica-Chlorit-Zone wird von einer Kaolinit-Mica-Montmorillonit-Zone überlagert, die an der Unteren Mergelplatte endet. Der Bereich zwischen der Unteren und der Oberen Mergelplatte (Bank 19 bis Bank 25) weist in der liegenden Hälfte eine Mica-Mixed-Layer-Montmorillonit-Zone mit Spuren von Chlorit und eine Mica-Montmorillonit-Zone im oberen Teil auf. Zusammenhänge zwischen dem Vorkommen von Onkoiden und Filament-Onkoiden sowie den Tonmineral-Assoziationen deuten auf spezifische klimatologische Bedingungen hin. Die Entwicklung eines tropisch humiden zu einem tropischen, semi-ariden Klima mit entsprechendem Verwitterungspotential kristalliner Gesteine des nahen Böhmischen Massivs und Bildungsbedingungen der Tonmineral-Assoziationen im Untersuchungsbereich ist wahrscheinlich
    Beschreibung: research
    Schlagwort(e): ddc:550
    Sprache: Deutsch
    Materialart: doc-type:article , publishedVersion
    Standort Signatur Erwartet Verfügbarkeit
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  • 37
    Publikationsdatum: 2022-07-26
    Beschreibung: Die verschiedenen architektonischen Baustile in einer Stadt geben der Nachwelt jeweils Zeugnis von der kulturellen und politischen Entwicklung. Dabei spielen die Baumaterialien vom historischen Naturstein bis hin zu den heute modernen technologischen Materialien (Kunststein, Glasbausteine, Beton, Metall etc.) eine wesentliche Rolle. Viele Jahrhunderte lang stand nur eine sehr begrenzte Palette an Naturwerksteinen zur Verfügung und es wurden zunächst sogenannte „Weichgesteine“ (Sandsteine, Kalkstein) genutzt, die leicht abzubauen und zu verarbeiten waren und die aus nahe gelegenen Abbaugebieten (»Steinbruch vor der Haustür«) stammten, oder auf Flüssen antransportiert werden konnten. Deshalb sind ältere Ortschaften und Städte durch eine lokalspezifische Gesteinsmonotonie gekennzeichnet, was sich in Erlangen in der Verwendung des in der Stadt und in der nahen Umgebung anstehenden Burgsandsteins widerspiegelt. Mitte des 19. Jahrhunderts traten für den technischen Aufschwung in der Steinindustrie entscheidende Veränderungen ein. Aufgrund der verbesserten maschinellen Bearbeitung kamen auch hier nun vermehrt Hartgesteine (Granit,Gabbro, Basalt) zur Verwendung. Durch neue Transportmöglichkeiten (Kanäle, Straße, Schiene) wurde auch die Einfuhr »exotischer Fremdgesteine« aus weitentfernten Abbaugebieten möglich. Seit der zweiten Hälfte des 19. Jahrhunderts kamen Kunststeine hinzu, mit denen natürliche Gesteine häufig perfekt imitiert werden können. Besondere politische Ereignisse, wie z. B. der deutsch französische Krieg (1870-1871) und damit zusammenhängend die Lieferungen von Fremdgesteinen nach Deutschland als Reparationsleistungen (Savonnières Kalkstein, Napoléon Kalkstein) dokumentieren noch heute markante Einschnitte in der Palette der verwendeten Naturwerksteine. In einem relativ engen Zeitfenster von der Hochzeit der Industrialisierung und auch der Deutschen Steinindustrie bis zu Beginn des ersten Weltkrieges (1900-1914) können diese vielschichtigen Einflüsse anhand von vier, in diesem Zeittraum errichteten Bauwerken in Erlangen exemplarisch aufgezeigt werden. Dabei geben auch die jeweiligen Zeitspannen von der Planung bis zur Fertigstellung und Einweihung der Gebäude Hinweise auf die politische und bautechnische Situation. Das Christian-Ernst-Gymnasium wurde aus der Prinz-Ludwig-Schule vom ersten Spatenstich im November 1901 bis zur Einweihung im November 1902 in nur einem Jahr fertig gestellt. Das Marie-Therese-Gymnasium, welches als neues Schulhaus in der Schillerstraße aus der »Städtischen höheren Töchterschule« hervorgegangen ist, wurde 1909 eingeweiht und erst 1965 offiziell als städtisches Marie-Therese-Gymnasium benannt. Die Universitätsbibliothek wurde 1910 geplant und nach der Grundsteinlegung 1911 bereits nach 2 Jahren Bauzeit im November 1913 eröffnet. Dabei hat der Termin des 170. Geburtstages der Friedrich-Alexander-Universität am 4. November 1913 sicher für entsprechenden Zeitdruck gesorgt und die Bauarbeiten beschleunigt. Der Bau des Instituts für Angewandten Chemie, der wahrscheinlich auch zur Unterstützung der Forschung an kriegswichtigen Materialen schnell errichtet werden musste, wurde nach kurzer Planung 1914 begonnen. Doch führten dann kriegsbedingte Schwierigkeiten, wozu wahrscheinlich auch der Mangel an Arbeitskräften aufgrund der Mobilmachung gehörte, zu großen Verzögerungen, weshalb der Rohbau erst 1916 fertiggestellt wurde und das Institut erst zum Wintersemester 1920 nach dem ersten Weltkrieg (1914-1918) bezogen werden konnte. Die Gestaltung der Front des Christian-Ernst-Gymnasiums, der Eingangsbereiche mit Portalen und Knaben- und Mädchenkopf aus schönem Roten Mainsandstein sowie einer darüber befindlichen Sandsteinbalustrade mit kunstvoll behauenen Vasen zeugen von einem ausgewogenen, repräsentativen Baustil. Die bronzene Büste des Prinzregenten auf einem Sockel aus ausgesuchtem hellem Untersberger Marmor (Kalkstein) sowie die ganze Gestaltung des Eingangsbereichs dokumentieren die positive Einstellung der Erlanger Bürger zu diesem Bauwerk. Die Gestaltung des Innenbereichs mit Wasserbecken aus poliertem Treuchtlinger Kalkstein sowie den beiden großzügig gestalteten Treppenhäusern mit Stufen aus Nammering Granit und schönen Holzbalustern bezeugen ebenso die gelungene architektonische Gesamtplanung wie auch die leider nicht mehr vollständig erhaltenen, geschwungenen Oberlichter über den Eichentüren zu den einzelnen Räumen. Auch die Gestaltung der Fußböden in den Gängen mit geschmackvollem Schwarz-Weiß-Muster der Bodenfliesen, die damals eine moderne technische Entwicklung (Trockenpressen) darstellten, lässt die Wertschätzung des Schulbaus bei den Bürgern und Architekten erkennen. Der Schulbau spiegelt auch heute noch die Freude am schönen Gestalten wider, die man damals hatte und in kurzer Zeit umsetzte und wirkt auch im Inneren heute noch fast fröhlich durch die von den beiden Treppenhäusern ausgehenden, lichtdurchflossenen Flure. Der heute als Marie-Therese-Gymnasium bekannt Bau in der Schillerstraße wurde etwa sieben Jahre später ebenfalls in sehr kurzer Bauzeit von der Planung 1908 bis zum Bezug 1909 des Neubau errichtet, der zunächst zur Unterbringung der »Städtischen höheren weiblichen Bildungsanstalt« diente. Der aufwändige neubarocke Stil ist trotz nachfolgender Veränderungen gut erhalten geblieben und zeigt auch noch das Chörlein an der Ostfassade vor dem 1956 erfolgten Erweiterungsbau. Muschelkalk und Coburger Bausandstein wurden für die Fassade ebenso wie am Christian-Ernst-Gymnasium verwendet und dokumentieren den Stil eines Schulbaus zu dieser Zeit. Doch wurden die Schmuckelemente des Eingangsportals mit großen Figuren und des großen Bayernwappens am Marie-Therese- Gymnasium aus grobporigem Muschelkalk geschlagen und kein feinkörniger Sandstein zur Modellierung verwendet. Eine Eingangshalle und ein trotz der Rundbögen geradliniges, kantig erscheinendes zentrales Treppenhaus weisen mehr auf einen pragmatischen Baustil im Inneren hin. Dieser Eindruck wird sowohl durch die intensive Verwendung von grobem Betonkunststein in Pfeilern und Balustern als auch durch einfarbige dunkelgrüne Wandfliesen und die teilweise verwendeten roten Bodenfliesen unterstützt. Die großen Keramikausgussbecken und besonders der Fußboden aus Linoleum, das sich in der zweiten Hälfte des 19. Jahrhunderts als moderner elastischer Bodenbelag durchgesetzt hat, zeigen im Innenbereich eine andere als im Christian-Ernst-Gymnasium, aber ebenfalls eine dem Stand der Technik zeitgemäße, moderne Gestaltung. Die ehemals verglasten, bunten Oberlichter, die dem Bau ein lichtdurchflossenes fröhliches Bild gaben, sind leider nicht mehr erhalten, weshalb der Eindruck im Inneren eher etwas klamm und gedämpft ist. Der geplante Besuch der Königsfamilie Ende Juli 1914 kam aufgrund des sich abzeichnenden Weltkrieges nicht zu Stande. Zu Ehren der Königin aber gab man dem Bau den Namen »Marie-Therese-Schule«, der 1965 von der Stadt in »Marie-Therese-Gymnasium« umgewandelt wurde. Der Neubau der Universitätsbibliothek, der 1910 geplant wurde, spiegelt in seinen beiden Teilen, dem Magazin- und dem Verwaltungstrakt eine komplexe Planungs- und Baugeschichte wider. Die Besuche der Planer von damals modernen Universitätsbibliotheken in anderen Universitätsstädten haben zu einem innovativen, dem neuesten Stand der Technik entsprechenden Magazintrakt mit selbst tragender Stahlkonstruktion geführt. Für den Außenbereich war die architektonische Eingliederung in die benachbarten Universitätsbauten im Markgrafenstil wie dem Kollegienhaus die Vorgabe. Dies wurde durch den Abriss der Reifbrauerei und die dadurch zur Verfügung stehenden Burgsandsteinquader begünstigt. Auch dass deren Menge nicht ausreichte, stellte kein Hindernis dar, konnten in dieser Zeit der Blüte von Steinbruchunternehmen doch problemlos zwei neue Brüche am Burgberg eröffnet werden. Die Gestaltung des Innenbereichs zeichnet sich durch architektonische, künstlerische Elemente aus, die sowohl durch Holzvertäfelung und Einbauten im Direktorenbereich und Sitzungssaal als auch durch die Auswahl der Naturwerksteine im Treppenhaus und in den Fluren einen repräsentativen Gesamteindruck vermitteln. Doch scheint hier gegen Ende der durch das 170-jährige Universitätsjubiläum (4. November 1913) vorgegebenen Bauzeit Zeitdruck entstanden zu sein, so dass manche Natursteinarbeiten nicht mehr mit der vorgesehenen Sorgfalt ausgeführt wurden. Dieser Umstand spiegelt sich besonders in den beidseitigen kastenartigen Konstruktionen aus nur 2 cm starken, schlecht verfugten Platten des Kalksteins Napoléon wider, die beidseitig des Treppenaufgangs angefertigt und mit zierlichen, zu klein erscheinenden Handläufen versehen wurden. Es kann angenommen werden, dass die Kalksteinplatten aus Reparationsleistungen des Deutsch-Französischen Krieges zu den Marmorwerken Funk in Nürnberg gelangt sind und hier verbaut wurden. In anderen repräsentativen Gebäuden dieser Zeit sind oft massive Geländer aus poliertem, edlem Naturstein zu finden. Auch die Platten aus Napoléon-Kalkstein in den Fluren erscheinen etwas rasch angebracht worden zu sein. Die grobkörnigen, bräunlichen Betonkunststeine aus denen die kurzen Mäuerchen mit Durchbruch und Holzbalustern und die Pfeiler hergestellt wurden, wirken leicht störend im gesamten repräsentativen Erscheinungsbild des Treppenhauses. Die schönen Rundbögen mit Kartuschen an den Eingängen zu den Fluren und vor allem die großen lichtgebenden Fenster aus Antikglas mit ziselierter Ornamentik verleihen dem Treppenhaus dagegen seinen großzügigen Eindruck. Das Gebäude der Universitätsbibliothek spiegelt den Wunsch nach einem hochmodernen (Magazintrakt) und gleichzeitig repräsentativen Gebäude (Verwaltungstrakt) wider. Die vollständige Umsetzung dieses Plans scheint unter dem Zeitdruck gelitten zu haben. Man griff daher wohl auch auf gerade verfügbares Material zurück, das wahrscheinlich günstig zu haben war und verwendete größere massive Kalksteine (Napoléon und Treuchtlinger Kalke) nur bei den beiden Wasserbecken in den Fluren. Auch die großen Säulen aus Muschelkalk zeigen, dass sie rasch und ohne weitere Qualitätsauswahl aus unterschiedlichen Muschelkalkschichten entnommen wurden, weshalb sie sowohl im als auch gegen das Lager übereinandergesetzt wurden, was bei derartigen Säulen steintechnisch nicht üblich ist. Der 1914 begonnene Bau des Instituts für Angewandte Chemie spiegelt seine besondere Bestimmung zur Förderung der Forschung im Zusammenhang mit dem ersten Weltkrieg eindrucksvoll wider. Der bis auf »heroische Figuren« über dem Eingangsbereich schnörkellose Bau zeigt die Vorherrschaft von Betonkunststein in der Fassade und in den großen Pfeilern im Treppenhaus. Die Elemente des vom Denkmalschutz besonders hervorgehobenen Holzzauns spannen sich zwischen mit grobem Beton überdeckte Backstein-Pfeilern, die heute besonders starke Schäden durch Abplatzen und Abschalen aufweisen. Der schmucklose Eingangsbereich leitet über zu einem ebenso schmucklosen Inneren mit überwiegend unterschiedlichen, einfarbigen Bodenfliesen und verschiedenen Kunststeinen. Nur die Eingangshalle ist mit dem für Bodenplatten besonders beliebten Solnhofener Kalkstein versehen. Ebenso sind nur der Gedenkstein an Prof. Max Busch, der damalige Rektor der Universität, und die Gedenktafel zur Würdigung der großzügigen Spender zur Errichtung des Baus in Treuchtlinger Kalkstein gefertigt wurden. Die Übergänge zwischen den verschiedenen Typen der Bodenfliesen sind abrupt und grenzen verschiedene Bereiche im Gebäude ab. Dazwischen wurde auch hier das damals hochmoderne Linoleum in großem Maße in unterschiedlichen Farben verwendet. Die großen Fenster aus Antikglas sind von besonderem Interesse. Hier wurde der Zweck des Baus in den verschiedenen Ornamenten in der Mitte der sechs Fenstereinheiten dokumentiert. Von der Erforschung der chemischen Elemente bis hin zu Düngemitteln und schließlich zum Sprengstoff wird der Einfluss der kriegswichtigen, praktischen Forschung deutlich. Die künstlerische Interpretation der hier schwerfälligen Rocaille-Ornamentik lässt keinen interpretatorischen Spielraum und ist wohl dem Wunsch des Auftraggebers angepasst, auf den sich der Künstler eingelassen hat. Glücklicherweise haben kriegsbedingte Schwierigkeiten dazu geführt, dass der Bau erst 1920 also etwa 2 Jahre nach dem Ende des ersten Weltkrieges bezogen werden konnte, und dadurch die kriegswichtigen Forschungsthemen anderen Schwerpunkten weichen mussten. Die Grundstücksgrenze zum heutigen Kitzmann-Areal stellt eine wertvolle, historisch verbürgte Grundstücksgrenze mit einem Teil der historischen Erlanger Stadtmauer dar, der auch bei heute eventuell anstehenden Baumaßnahmen nicht verändert werden darf. Das Direktionszimmer, das sich zentral in der zweiten Etage befindet, fällt aus dem Rahmen des nüchternen Zweckbaus. Hier wurde, wie im Direktionszimmer der Universitätsbibliothek, ein repräsentativer Raum mit einer Verkleidung und Wandschränken aus Eichenholz geschaffen. Dieser Raum wurde in den letzten Jahren als Bibliothek genutzt. Wie in der Universitätsbibliothek sollte das Ensemble des historischen Raumes unter Denkmalschutz gestellt werden
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: research
    Schlagwort(e): ddc:550
    Sprache: Deutsch
    Materialart: doc-type:article , publishedVersion
    Format: 67
    Standort Signatur Erwartet Verfügbarkeit
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  • 38
    Publikationsdatum: 2022-12-15
    Beschreibung: Seit nunmehr 50 Jahren erscheinen die Mainzer Geowissenschaftlichen Mitteilungen (MGM) des Landesamtes für Geologie und Bergbau, vormals Geologisches Landesamt. Grund genug, Rückschau zu halten und dieses kleine Jubiläum mit einem eigenen Beitrag in den MGM zu würdigen. In den vergangenen 50 Jahren hat nicht nur das Layout Veränderungen erfahren, auch weitere Themen sind entsprechend neuen Aufgaben des Geologischen Dienstes hinzugekommen und haben das Spektrum des Inhaltes erweitert.
    Beschreibung: Abstract: With the current issue the journal "Mainzer Geowissenschaftliche Mitteilungen" (MGM) celebrates its 50th birthday - a good reason for a retrospective view on the history of the journal. During the past 50 years not only the layout has changed several times but also new topics were introduced eventually according to changing and expanding tasks of the Federal Geological Survey.
    Beschreibung: editorial
    Schlagwort(e): ddc:550 ; Verlagswesen
    Sprache: Deutsch
    Materialart: doc-type:article , publishedVersion
    Standort Signatur Erwartet Verfügbarkeit
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  • 39
    Publikationsdatum: 2022-12-15
    Beschreibung: The subduction of serpentinized slabs is the dominant process to transport “water” into Earth's mantle, and plays a pivotal role for subduction dynamics. Antigorite, the most abundant serpentine mineral in subduction settings, may imprint a seismic signature on serpentinized slabs, making them seismically distinguishable from the dry, non‐serpentinized ones. However, the complete single‐crystal elasticity of antigorite has not been experimentally constrained at high pressures, hindering the use of seismological approaches to detect serpentinization in subducting slabs. Here, we report the full elastic stiffness tensor of antigorite by single‐crystal Brillouin spectroscopy and X‐ray diffraction up to 7.71(5) GPa. We use our results to model seismic properties of antigorite‐bearing rocks and show that their seismological detectability depends on the geometrical relation between seismic wave paths and foliation of serpentinized rocks. In particular, we demonstrate that seismic shear anisotropy shows low sensitivity to serpentinization for a range of relevant geometries.
    Beschreibung: Plain Language Summary: The subduction of serpentinized slabs plays a key role in the deep recycling of water into the Earth's interior. Antigorite is the main serpentine mineral in subducting slabs, and the most important carrier of water. Antigorite‐bearing rocks are predicted to have a distinct seismic signature, potentially allowing them to be detected with seismological approaches. However, our current knowledge on seismic properties of antigorite‐bearing rocks is limited, mostly hampered by a lack of experimental constraints on single‐crystal elasticity of antigorite at relevant pressures. In this study, state‐of‐the‐art techniques were employed to produce the first experimental description of the complete high‐pressure elasticity of antigorite single crystals. Our experimental data set was implemented in the modeling of seismic properties of antigorite‐bearing rocks at pressures relevant for subduction. Our results were used to discuss the relation between seismic wave path and shear wave anisotropy in serpentinized slabs, and challenge the use of shear wave splitting as a proxy for serpentinization in slabs.
    Beschreibung: Key Points: Single‐crystal elasticity of antigorite at high pressures is determined by Brillouin spectroscopy and X‐ray diffraction experiments. Seismic signature of serpentinized slabs is constrained in a relevant composition‐pressure space. Serpentinization in slabs may be undetectable through shear wave anisotropy.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Beschreibung: EC Horizon 2020 Framework Programme http://dx.doi.org/10.13039/100010661
    Beschreibung: https://doi.org/10.6084/m9.figshare.20348748
    Beschreibung: https://doi.org/10.6084/m9.figshare.20348781
    Schlagwort(e): ddc:550 ; serpentine ; elasticity ; Brillouin spectroscopy ; antigorite ; seismic anisotropy ; shear wave splitting
    Sprache: Englisch
    Materialart: doc-type:article
    Standort Signatur Erwartet Verfügbarkeit
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  • 40
    Publikationsdatum: 2022-12-01
    Beschreibung: Geological maps are complex to produce through intensive and expensive field studies. Comparisons of geophysical data with geological conditions are difficult and often only qualitatively possible. The following work therefore examines an automated procedure to better reconcile this information. For this purpose, the terracing method, and a cluster analysis of potential field (gravity and magnetic field) and petrophysical data from the Karasjok and Ligurian Sea regions are used to interpret this geophysical measurements in a geological way. Two different tectonic regions were selected: (1) The Karasjok region is located in Northern Norway, where the Karasjok Greenstone Belt (KGB) dominates geological settings, consisting of abundant ultramafic intrusions, komatiites, gabbroic intrusions, amphibolites and migmatites. (2) The Ligurian-Provençal basin, part of the Western Mediterranean Sea, which is located between the French-Italian coastline and the island of Corsica. Geologically the area is characterised by the spreading zone in the Western Mediterranean. The high-resolution Airborne Gravity Gradient Survey and aeromagnetic datasets of the Karasjok region cover an area of 20 km x 30 km with a data resolution of 50 m. The dataset of the Ligurian basin cover a much larger area with the resolution of 5 km. Data constraints come from former LOBSTER and LISA campaigns and a study in the research group at CAU Kiel, new compilation of the AlpArray Gravity Research Group (AAGRG), besides data of the ICGEM Potsdam (disturbance) and the GOCE mission. By aid of the terracing algorithm, the boundaries of the anomalies are to be sharpened and regions with constant field amplitude were generated. For this purpose, a shape index-based algorithm was applied, which uses the shape index calculated at each field point to grade the function. Through an iterative process and the variation of parameters, the terracing result is refined. The resulting data sets are then further processed using a cluster analysis method. Here, the k-mean algorithm for domain classification is used to divide the geophysical measurement data into groups (cluster) of similar properties. The number of clusters k is specified and the data points are assigned to the respective clusters through an iterative process. Using the data of the datasets mentioned above the results of this applications are successfully compared with the corresponding geological maps of the two areas.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG), SPP "MB-4D"
    Beschreibung: https://doi.org/10.5880/fidgeo.2020.045 (Zahorec et al., 2021) via GFZ Data Services
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Clustering ; terracing ; gravity field ; Liguro-Provencial Basin
    Sprache: Englisch
    Materialart: doc-type:conferenceObject
    Standort Signatur Erwartet Verfügbarkeit
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  • 41
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2022-12-01
    Beschreibung: Der Hessische Erdbebenkatalog ist eine Zusammenstellung historischer und aktueller Informationen zu Erdbeben in Hessen und direkter Umgebung von Hessen. Er wird vom Hessischen Erdbebendienst geführt und regelmäßig aktualisiert. Eine 50 km-Umhüllende wurde um Hessen herum gelegt, um auch Erdbeben und die dazugehörenden Bereiche zu betrachten, die Auswirkungen auf Hessen haben können. Eine Vollständigkeit wird jedoch nur für das Gebiet des Landes Hessen angestrebt. Für den seismischen Katalog Hessen (SKHe2022) wurden verschiedene, verfügbare Erdbebenkataloge und Ausarbeitungen zu Grunde gelegt. Des Weiteren beinhaltet der Katalog Ereignisse aus mehreren wissenschaftlichen Publikationen. Das Stichdatum für den Katalog ist der 31.12.2021. Der Erdbebenkatalog Hessen wird auch in Zukunft fortgeschrieben und ist damit als Zwischenstand zu sehen. In Zukunft wird er halbjährig aktualisiert und der Öffentlichkeit über den Geologie-Viewer des Hessischen Landesamtes für Naturschutz, Umwelt und Geologie unter geologie.hessen.de zur Verfügung gestellt. Im seismischen Katalog Hessen werden fünf Zeiträume beschrieben. Dabei handelt es sich für den Zeitraum 800 bis 1700 um Daten, die aus Chroniken ermittelt wurden. Für den Zeitraum 1701 bis 1950 beruhen viele der älteren Ereignisse auf makroseismischen Daten. Durch den aufkommenden Zeitungsdruck wurden wesentlich mehr Daten erhoben als in dem Zeitraum davor. Seit Anfang des 20. Jahrhunderts wurden dann auch Erdbeben instrumentell aufgezeichnet. Das analog-instrumentelle Zeitalter wird für den Zeitraum 1951 bis 1975 angegeben. Das digital-instrumentelle Zeitalter gilt ab 1976. Es wurde eine Priorisierung der einzelnen Erdbebenereignisse, wenn mehrere Ereignisse von unterschiedlichen Quellen aufgezeichnet wurden, durchgeführt. In der aktuellen Version sind sämtliche bekannte induzierte Ereignisse identifiziert worden. In der veröffentlichten Version sind diese induzierten Ereignisse nicht mehr enthalten, so dass der Erdbebenkatalog des Landes Hessen als rein tektonischer, auf natürlichen Erdbeben basierender, Erdbebenkatalog angesehen werden kann. Die stärksten historischen Erdbeben traten in den Jahren 858, 1733 und 1858 in Mainz, 1619 im südlichen Taunus, 1767 in Rothenburg/Fulda, sowie als Erdbebenschwarm in Groß-Gerau (1869-1871), 1871 in Lorsch und im Odenwald auf. Das stärkste Erdbeben in den letzten Jahren fand im Jahr 2014 bei Ober-Ramstadt im Odenwald mit einer Magnitude von 4,2 statt.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Erdbeben ; Seismischer Katalog ; Hessen ; Oberrheingraben
    Sprache: Deutsch
    Materialart: doc-type:conferenceObject
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  • 42
    Publikationsdatum: 2022-12-01
    Beschreibung: Aeromagnetic surveys help us to learn about geology. To achieve good coverage, surveys need to be merged. However, conventional methods introduce long-wavelength bias and cannot handle the individual survey quality. We develop a new approach to process large aeromagnetic surveys with an equivalent layer approach and combine them with satellite data. To facilitate the usage of large data sets, we divide the study area into blocks and treat each block individually. We adjust the block size according to the resolution of the equivalent source model. Within each block we solve for equivalent sources using an iterative linear inversion with Tikhonov regularization. We apply a multi-resolution strategy by iteratively decreasing the dipole spacing, dipole depth and block size. In each step, the resolution is applied to the residual of the previous steps. This ensures both a good representation of the large and small-scale structures as well as reasonable computational costs. Advantages of the blockwise inversion are the handling with large data sets due to splitting up the study area and neglecting influences of sources above a certain distance. This reduces computational costs and still fits the data well in comparison with an unblocked inversion. Some structures cannot be resolved well with just one dipole layer, so the multi-resolution strategy enables to have a better fit by separating regional and local sources. For the final compilation, we replace the long wavelengths part of the aeromagnetic data with satellite data to spherical harmonic degree 110. We demonstrate our new approach with a newly compiled large data base for Greenland.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; aeromagnetic ; inversion ; greenland ; multi-layer
    Sprache: Englisch
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  • 43
    Publikationsdatum: 2022-12-01
    Beschreibung: In Folge des Klimawandels kommt es in Mitteleuropa vermehrt zu Dürreperioden und Austrocknung von Böden. Indem tief- und flachwurzelnde Nutzpflanzen sinnvoll kombiniert werden, kann die Verfügbarkeit von Wasser teils auch ohne künstliche Bewässerungsmaßnahmen verbessert werden. Die Tiefwurzler erschließen tiefer gelegenes Wasser und können es so umverteilen (‚hydraulische Umverteilung‘), dass auch benachbarte Flachwurzler mit Wasser versorgt werden. Mit dem Ziel eine solche Umverteilung von Wasser durch Pflanzen mithilfe geoelektrischer Methoden zu untersuchen, wurde in dieser Studie ein Versuchsaufbau entwickelt und getestet. Auf 23 Feldern wurden verschiedene Kombinationen der Pflanzen beobachtet. Dafür wurden sowohl Oberflächenmessungen mittels Gleichstromgeoelektrik, als auch Bohrlochmessungen mittels Spektraler Induzierter Polarisation (SIP) durchgeführt. Die Ergebnisse wurden mit konventionellen Bodenfeuchtemessgeräten (time domain reflectometry, TDR) verglichen, welche die Bodenfeuchte nur punktuell erfassen können. Für die Bohrlochmessungen wurde ein experimenteller Aufbau zur Beobachtung der räumlichen Verteilung des Wassers im Untergrund umgesetzt. Um eine hohe Auflösung im Bereich der flachen Wurzeln zu erreichen, wurde ein bohrlochartiges System genutzt. Dieses besteht aus metallischen Ringelektroden, die an einem Holzstab befestigt sind, der senkrecht in den Boden eingebracht wird. Die Elektroden haben dabei nahe der Oberfläche die kleinsten Abstände (5cm), da in diesem Bereich die Wurzeln der Tief- und Flachwurzler gemeinsam vorkommen. Hier soll die Auflösung möglichst hoch sein, damit die Wasserumverteilung gut beobachtet werden kann. Mit zunehmender Tiefe nehmen die Elektrodenabstände zu. Hier ist eine geringere Auflösung ausreichend, da nur die Tiefwurzler Wasser aufnehmen. Da die Stäbe bereits vor dem Sähen der Pflanzen in den Boden gebracht wurden, war ein Monitoring über mehrere Monate möglich: Zur Aussaat der Pflanzen Ende März, während des Wachstums und im September während eines finalen Bewässerungsexperimentes. Die bisherigen Auswertungen der Ergebnisse zeigen, dass sich die zeitliche Entwicklung der Bodenfeuchte anhand der geoelektrischen Daten gut nachvollziehen lässt und im Gegensatz zu den TDR-Daten auch die räumliche Verteilung hoch aufgelöst (〈5cm) erfasst werden kann. Die Oberflächenmessungen zeigen, dass die Schichtung des Bodens über die Plots variiert, was sich auf die Vergleichbarkeit der Ergebnisse auswirken kann.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Geophysik ; Geoelektrik ; Monitoring ; Induzierte Polarisation
    Sprache: Deutsch
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  • 44
    Publikationsdatum: 2022-12-01
    Beschreibung: Recent years have shown an increased interest in Polar research and in particular in understanding tectonics and seismic hazard in the Arctic. To understand the seismic activity in the European Arctic, the seismic bulletins should be as complete as possible. We present a new seismic event bulletin for the European Arctic (70° – 90° N, -15° – 75° E), for the 24-year long period 1990 – 2013. The poster will show in detail the merging of the different sources taken in account for the compilation, the homogenization of the data and the relocation of the seismic events. With respect to the ISC bulletin for this region, the new bulletin contains 5,932 new seismic events and 54,630 new seismic onset readings from stations mostly located at regional distances. The gains are distributed over the entire study region, with the most significant contributions across the Svalbard Archipelago, along the Knipovich and northern Mohns Ridges, as well as northern Fennoscandia.
    Beschreibung: Norwegian Research Council Grant 233973/H30
    Beschreibung: Russian Foundation for Basic Research Grant 14-05-93080
    Beschreibung: Russian Foundation for Basic Research Grant 18-05-70018
    Beschreibung: https://doi.org/10.31905/TYLLQY8T
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; European Arctic ; Seismic Bulletin
    Sprache: Englisch
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  • 45
    Publikationsdatum: 2022-12-01
    Beschreibung: During the last few years, the use of Ground-Penetrating-Radar (GPR) multi-channel antenna arrays in the Archaeological Prospection increased dramatically. The main advantage of this type of survey is a much faster data acquisition combined with a dense profile spacing. However, most of the common multi-channel arrays consist of antennae with a spacing of not smaller than 8 cm. The aim of our test survey was to evaluate how an even denser spacing of 4 cm that is provided by the IDS Stream-C GPR device at a centre frequency of 600 MHz can improve the detection of small archaeological features. As a test site, we chose the Great Bath in Kempten-Cambodunum. This first capital of the Roman province Rhaetia never has been overbuilt in the following centuries and even today it is used as a grassland declared as an Archaeological Park. Already in 1911, the Great Bath was excavated and beside the walls of different building phases, also small features like a multitude of hypocaust pillars were unearthed. Hence, this building structure depicts an ideal test site and a 40x40m grid covering the main part of the construction was chosen for the application of the antenna array. As a comparison, the same grid was contemporaneously surveyed with a single antenna IDS Duo device (600 and 200 MHz) and a 50 cm profile spacing. Regarding the walls of the Roman bath, the two surveys show comparable results: both datasets represent the stone constructions of 50 – 90 cm width quite well. Furthermore, the depth slices of both devices provide a differentiation of the single building phases. Nevertheless, the resolution for the multi-channel antenna array is of course much higher due to the denser profile spacing. Huger differences occur for the hypocaust pillars of 25 cm lateral length. These features can be mapped in detail with the 4 cm profile spacing of the IDS Stream-C system. Whereas the IDS Duo can only resolve some of the hypocausts, a multitude of them gets visible between 70 and 110 cm depth in the Stream-C data. As a conclusion, it can be stated that standard archaeological remains like stone walls, for sure, can be surveyed with single antenna GPR devices in a common profile spacing of 50 cm. However, in case of the existence of faint archaeological features the application of ultra-dense antenna arrays like the IDS Stream-C is advisable to get a comprehensive overview of a site without the necessity to excavate them.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Ground-Penetrating Radar ; GPR ; Multichannel Antenna Array ; Roman Bath ; Hypocaust Pillars
    Sprache: Englisch
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  • 46
    Publikationsdatum: 2022-12-01
    Beschreibung: Mit dem zerstörungsfreien Verfahren der nuklear magnetischen Resonanz (NMR) mit Fokus auf 1H-Protonen lässt sich der Feuchtegehalt in porösen Materialien bestimmen und bei einem vollgesättigten Medium eine Porengrößenverteilung ableiten. Für die Ermittlung der Porengrößenverteilung muss die gemessene T2-Relaxationszeitenverteilung mit dem Parameter Oberflächenrelaxivität (OR) umgerechnet werden. Ist dieser Parameter für das zu untersuchende Medium unbekannt, kann dieser mithilfe von Vergleichsverfahren abgeschätzt werden. Dabei kommen z. B. Gassorption, Quecksilberporosimetrie (MIP), Dünnschliff-Mikroskopie oder µ-Computer-Tomographie (µ-CT) zum Einsatz. Da die verschiedenen Verfahren allerdings unterschiedliche Auflösungsgrenzen aufweisen und auf verschiedenen physikalischen Prinzipien beruhen, können die ermittelten ORs für ein Medium stark variieren. Um ein besseres Verständnis für die OR und die Einflüsse der Vergleichsverfahren zu bekommen, wurden 19 verschiedene Sandsteintypen untersucht. Die OR wurde zum einen basierend auf der spezifischen inneren Oberfläche aus der dynamischen Dampfsorption (DVS) und der Gassorption abgeleitet. Zum anderen wurden die Relaxationszeitenverteilungen durch manuelles Anpassen der OR derart in Porengrößenverteilungen umgerechnet, sodass es eine Übereinstimmung mit den Porengrößenverteilungen aus MIP und/oder µ-CT gibt. Die Umrechnung von Relaxationszeitverteilungen in eine Porengrößenverteilung berücksichtigt dabei sowohl fast- als auch slow-diffusion. Insgesamt ergab sich für die Sandsteine ein breites Spektrum an ORs, bei dem die über die innere spezifische Oberfläche ermittelten ORs andere Größenordnungen aufwiesen (〈 10 µm/s), als bei dem Vergleich mit MIP oder µ-CT (bis 600 µm/s). Die mit MIP und µ-CT ermittelten Werten lagen dabei um einen Faktor von 1 bis 30 auseinander. Dieser umfangreiche Datensatz, der vier verschiedene Vergleichsverfahren einbezieht, soll neue Erkenntnisse in der Charakterisierung von porösen Materialien (z. B. bezüglich der Oberflächenrauigkeit) und in der Ursache für die starke Variation der OR ermöglichen. Durch das Berücksichtigen von fast- als auch slow-diffusion, können dabei sogar Daten in eine Porengrößenverteilung umgerechnet werden, bei denen das fast-diffusion-Kriterium nach Brownstein und Tarr nicht erfüllt ist. Außerdem ergibt sich aus der Berücksichtigung des slow-diffusion-Regimes ein neues Verständnis für die obere Auflösungsgrenze von NMR.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Nuklear magnetische Resonanz ; Oberflächenrelaxivität ; Sandsteine
    Sprache: Deutsch
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  • 47
    Publikationsdatum: 2022-12-01
    Beschreibung: Das Poster präsentiert die Ergebnisse des kombinierten Einsatzes von NMR und LIBS zur Verfolgung von Feuchtigkeit und Schadionen in Baustoffen. Es wurden dazu mit zwei Sandsteine und zwei zementäre Baustoffe kapillare Saugversuche durchgeführt. Die Materialien wurden 5 mm tief in Natriumchloridlösungen einer Konzentration von 1 mol/l und 4 mol/l getaucht. Mit NMR wurde der Feuchteanstieg, mit LIBS der Chloridionenanstieg ermittelt. Ergebnisse sind unter anderem, dass die Feuchte den Ionen immer vorauseilt. Außerdem ist die Anstiegsgeschwindigkeit direkt abhängig vom Porensystem und von der Lösungskonzentration.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; NMR ; LIBS ; Transportprozesse ; Ionentransport ; Feuchtetransport
    Sprache: Deutsch
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  • 48
    Publikationsdatum: 2022-12-01
    Beschreibung: The Floodrisk project takes a muti- and interdisciplinary look on the effects of the rise in mine water level in abandoned coal mine regions in Germany. Such effects are heterogeneous ground uplift, stress changes due to the pore pressure changes and the reactivation potential of faults. One of the most directly measurable effects is the induced seismicity. It is known from previous studies that the flooding of old mines can lead to a renewed increase in induced microseismicity in these regions. We focused on the observation of the eastern Ruhr area and investigate in detail the relationship between mine water rise and induced seismicity in the Haus Aden dewatering area. For this purpose, we operate a network of up to 30 short period seismic stations in the region of the former "Bergwerk Ost" colliery, which had the highest seismicity rate in the Ruhr area during active mining. Continuous monitoring of seismicity and mine water levels is available for this region from the active mining phase, through the post-mining phase to flooding. Since the beginning of the flooding, more than 20000 onsets were picked and over 1700 induced events were localised in a magnitude range from -0.7 up to 2.6 MLv. For some larger events, focal mechanisms could be determined. The spatial distribution of hypocentres is divided into two areas, with few events in the central study area and over 95% of earthquakes in its eastern part. Many of these events are spatially clustered and some show quite high waveform similarity. This allows relative localisation to increase the accuracy of the location. Comparing the old galleries,which today serve as the main underground waterways, with the localisations from the relative localisation, strong correlations can be seen. The measured temporal trend of the mine water level, after pumps were shut down in mid-2019, shows a strong correlation with the temporal evolution of the observed micro seismicity. In the first months after the pumps are switched off, the water levels at the observation points rise only slowly and isolated microseismic events occur again. In November 2019, the rise in water levels doubled and at the same time, the strongest induced event in the measurement period was recorded with a magnitude of 2.6 MLv. In the years 2020, 2021 66 and 58 events 〉= MLv 1 were observed, respectively. In contrast to this number only 2- 9 events 〉= MLv 1 per year were observed in the post-minig phase before flooding.
    Beschreibung: Bundesministerium für Bildung und Forschung
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; induced seismicity ; post mining ; mine water rise ; Ruhr Area
    Sprache: Englisch
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  • 49
    Publikationsdatum: 2022-12-01
    Beschreibung: In the last few years, several Unmanned Aerial Vehicle (UAV) based magnetometer systems have been tested for archaeological prospection. Due to their higher sensitivity, scalar magnetometers have been preferred as test sensors. However, total field magnetometer are vulnerable to disturbances, especially those generated by the UAV itself. Therefore, most UAV scalar magnetometer systems use the method of increasing the distance between magnetic sensors and the UAV to reduce interference. But freely suspended sensors tend to swing on ropes under the UAV and can produce data that are strongly influenced by heading errors. For our test, we therefore chose the UAV-fixed, compact setup of the SENSYS MagDrone R4, which is equipped with five three-axis FGM3D/75 fluxgate sensors at 50 cm spacing and is covering a swath width of 2.5 m. The 200Hz sampling rate of the R4 allows easy filtering of interference generated by the UAV and external disturbances like power lines or infrastructure. Magnetograms with a spatial resolution of up to 0.20 m per pixel were produced from the data. At Ganacker, we chose the former infrastructure core of the World War II German Air Force airfield as a test site. A wide range of archaeological structures and features with high magnetic contrast were expected on this area. The test site is currently an open agricultural area with a quite flat terrain. Hence, the R4 could be operated at a fixed flight height of just one metre above the surface of the terrain that is controlled actively by a radar sensor. An area of around 110 hectares were prospected within only four days. The MagDrone R4 system thus offers an outstanding survey area progress that cannot even reached by common vehicle-moved multi-sensor arrays. Here, we present the first results of this test survey by comparing the magnetograms, historical and current geodata. Most of the expected archaeological features and several unknown ones were detected by the R4 system. Our results show that the R4 system is well suited for mapping large archaeological structures with high magnetisations. In the future, we want to compare the R4 data with data from a ground-based fluxgate magnetometer. We also want to test whether the system is suitable for detecting archaeological features that have lower magnetic susceptibility and remanence contrasts with the surrounding soil.
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; UAV magnetometer survey ; 3-axis fluxgate magnetometers ; archaeological prospection ; low-level flight ; Second World War airfield ; conflict landscapes
    Sprache: Englisch
    Materialart: doc-type:conferenceObject
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  • 50
    Publikationsdatum: 2022-12-01
    Beschreibung: Das Ziel des COSC-2 (Collisonal Orogeny in the Scandinavian Caledonides) Projektes ist es, die Entstehungsprozesse der Skanden zu untersuchen. Hierfür sind Kenntnisse über die Deformationen / Faltungsprozesse von großer Wichtigkeit, die sich aus der Richtung der remanenten Magnetisierung ableiten lassen. Die teufenabhängigen Magnetisierungsvektoren lassen sich aus dreikomponetigen Bohrlochmagnetikdaten berechnen. Als Datengrundlage dienen Messungen, die mit einem Dipmeter in der COSC2-Bohrung in Järpen (Schweden) durchgeführt wurden. Es wurden 5 Messungen mit 1cm Messpunktabstand in verschiedenen Teufenbereichen zwischen 100m und 2250m Teufe aufgezeichnet. Anhand der in der Sonde verbauten Accelerometer und dem bekannten Verlauf der Bohrung konnten die Magnetfelddaten in das geographische Referenzsystem reorientiert werden. Die erreichte Genauigkeit beträgt 1,5° in der Deklination und 0,16° in der Inklination. Um die Magnetisierung der durchbohrten Gesteinseinheiten zu bestimmen wird an die reorientierten Magnetfelddaten ein Schichtmodell nach Bosum et al (1988) angepasst. Dieses Modell nähert die Schichten durch zentral durchbohrte Zylinder. Das Modell von Bosum geht von einem Zylinder aus, der senkrecht zu den Deckflächen zentral durchbohrt wird. In der COSC-2 Bohrung ist aber zum einen das Bohrloch geneigt, zum anderen weisen auch die durchbohrten Schichten eine Neigung auf. Aus diesem Grund erweitern wir das Bosum-Modell nach Ehmann (2016) für beliebige Schichtinklinationen. Die Schichtmächtigkeiten werden durch die Lithologie der Bohrung bestimmt, die aus den Bohrkernen abgeleitet wurde. Eine erste Analyse zeigt, dass in den oberen 1200m der Bohrung nur schwach magnetisierte Gesteine vorherrschen. Darunter folgen stärker magnetisierte-Schichten, die im Mittel eine Magnetisierung von 1A/m aufweisen. Im Bereich von 1590m bis 1850m befindet sich eine stark magnetisierte Sektion, die sich in vier Bereiche aufteilen lässt. Die Magnetisierung in dieser Sektion beträgt bis zu 5 A/m. In der stark magnetisierten Sektion können zwei Bereiche identifiziert werden, in denen die Inklination der Magnetisierungen von 40° auf bis zu 80° ansteigt. Die beiden Bereiche mit hoher Inklination weichen in ihrer Deklination von der mittleren Deklination der Sektion um +90° und -90° ab. Diese Variationen deuten auf Deformationen der Gesteinsschichten hin. Unterhalb dieser Sektion schließt sich eine Sektion mit Magnetisierungen von etwa 1 A/m und Inklinationen von etwa 15° an.
    Beschreibung: DFG, Fördernummer VI 836/5-1
    Beschreibung: poster
    Schlagwort(e): ddc:550
    Sprache: Deutsch
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  • 51
    Publikationsdatum: 2022-11-29
    Beschreibung: Anlässlich des Arbeitstreffens der GeoUm im Rahmen des Bibliothekskongresses 2022 wurde eine kurze Bilanz für den FID GEO bis heute und ein Ausblick auf geplante Entwicklungen für die aktuell beantragte 3. Förderphase vorgetragen
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Fachinformationsdienst Geowissenschaften
    Sprache: Deutsch
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  • 52
    Publikationsdatum: 2022-11-29
    Beschreibung: Die DFG-geförderten Fachinformationsdienste FID GEO, FID Karten und FID Montan unterstützen ihre jeweils eigene Fachcommunity und agieren zudem als gemeinsames Cluster für das System Erde. Im Zentrum stehen elektronisches Publizieren, Erwerbung und Digitalisierung von Spezialliteratur und Karten sowie die Unterstützung bei der Beschaffung von Geodaten und der Publikation von Forschungsdaten. Spezielle Rechercheinstrumente und in den Suchraum eingebundene fachspezifische Literaturnachweisdatenbanken bieten qualifizierten Zugang zu Informationen. Die hier vorgestellten Fachinformationsdienste kooperieren eng miteinander und ergänzen sich in ihren Angeboten für eine verbesserte Forschungsumgebung in der Erdsystemforschung im Sinne offener Wissenschaft. Das gemeinsame Ziel ist, aus dem FID-Cluster ein echtes Netzwerk zu knüpfen, welches interdisziplinär agiert und gleichermaßen fachspezifisch die Bedarfe der Wissenschaft bedient. Die drei Fachinformationsdienste werden einige ihrer Services kurz vorstellen, Beispiele einer kooperativen Zusammenarbeit und gemeinsame Herausforderungen präsentieren.
    Beschreibung: DFG, SUB Göttingen,TU Bergakademie Freiberg, TU Berlin, GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; ddc:020 ; ddc:900 ; FID ; Karthographie ; Geowissenschaften ; Montan
    Sprache: Deutsch
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  • 53
    Publikationsdatum: 2022-11-29
    Beschreibung: In diesem Poster sollen die Möglichkeiten des offenen Publizierens in den Geowissenschaften, von der Probe über die Daten bis zum fertigen Manuskript und wie der FID GEO diesen Prozess begleitet, gezeigt werden. Hierbei liegt der Fokus auf den Services und Informationssystemen, die dauerhaft verfügbare und verlässlich zitierbare elektronische Publikationen von Schriften und Daten gewährleisten. Es soll das Potenzial und die Nutzbarkeit der beiden Repositorien vorgestellt werden. Der Service der Publikation von Schriften wird im Fachinformationsdienst-eigenem Fachrepositorium GEO-LEOe-docs bereitgestellt. Das fachspezifische Forschungsdaten Repositorium GFZ Data Services steht für die Veröffentlichung von Forschungsdaten und wissenschaftlicher Software aus den Erd- und Umweltwissenschaften zur Verfügung.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Geowissenschaften ; Fachinformationsdienst ; FID GEO
    Sprache: Deutsch
    Materialart: doc-type:conferenceObject
    Standort Signatur Erwartet Verfügbarkeit
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  • 54
    Publikationsdatum: 2022-11-29
    Beschreibung: Knowledge sharing in academia has been considered indispensable and is becoming a priority in most European funding schemes. Although we are already quite familiar with the different possibilities to publish our results in open-access journals, open science means way more than that. Open science aims at opening up research processes and granting access to research outputs to researchers, professionals and amateur scientists. There are different ways to ensure the storage and reusability of our data, making it available to other scientists. Furthermore, most of the scientific disciplines migrate their analyses to open-source environments (e.g., R, Phyton). However, tons of code produced remain stored in our personal computers either because we do not know the appropriate tools to share them with our colleagues or because we believe that it is not well structured. In this short course, you would learn how to establish links between publications, data, software and methods. Hence, we will discuss with our experts: i) the options to share our data and code with other peers, ii) obtain some tips to better organize our scripts, and iii) uncover potential barriers to sharing research and discuss possible solutions.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Repository ; Data Management ; Open Science
    Sprache: Englisch
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  • 55
    Publikationsdatum: 2022-11-29
    Beschreibung: The rise of Open Science practices is impacting the entire scientific publishing culture. The transition to Open Access for text publications goes hand in hand with the growing demand to make scientific data and software available to the general public. The FAIR data principles play a key role in this, designed to make research and the underlying data easily findable, accessible, interoperable, and reusable for humans and machines. Geosciences data are as diverse as their content. They range from large real-time data streams of international observing networks to small data sets produced by individual researchers at their laboratories. Consequently, there need to be different strategies for data management and publication in which research data repositories can be important partners for the researchers. The Specialised Information Service for Geoscience (FID GEO) is a DFG-funded project that is promoting a holistic approach of Open Science that includes scholarly literature, data, samples, and scientific software equally and pushes for their interlinkage. FID GEO has become an important player for connecting researchers, data repositories, information infrastructures, German geoscientific societies, and publishers. FID GEO actively provides data and text publishing services through its affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as on-demand digitization of printed geoscience literature and maps. In addition, FID GEO aims to inform the German-based geoscience community about all aspects of Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: http://doi.org/10.5194/egusphere-egu22-13354
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Open Science ; Geoscience
    Sprache: Englisch
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  • 56
    Publikationsdatum: 2022-11-29
    Beschreibung: The rise of Open Science practices is impacting the entire scientific publishing culture. The transition to Open Access for text publications goes hand in hand with the growing demand to make scientific data and software available to the general public. The FAIR data principles play a key role in this, designed to make research and the underlying data easily findable, accessible, interoperable, and reusable for humans and machines. Geosciences data are as diverse as their content. They range from large real-time data streams of international observing networks to small data sets produced by individual researchers at their laboratories. Consequently, there need to be different strategies for data management and publication in which research data repositories can be important partners for the researchers. The Specialised Information Service for Geoscience (FID GEO) is a DFG-funded project that is promoting a holistic approach of Open Science that includes scholarly literature, data, samples, and scientific software equally and pushes for their interlinkage. FID GEO has become an important player for connecting researchers, data repositories, information infrastructures, German geoscientific societies, and publishers. FID GEO actively provides data and text publishing services through its affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as on-demand digitization of printed geoscience literature and maps. In addition, FID GEO aims to inform the German-based geoscience community about all aspects of Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Open Science ; Geoscience
    Sprache: Englisch
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  • 57
    Publikationsdatum: 2022-11-29
    Beschreibung: FZ Data Services is a domain repository for geosciences data comprising the Earth, Space and Environmental Sciences. It assigns digital object identifier (DOI) to data and scientific software since 2004. Hosted at the GFZ German Research Centre for Geosciences (GFZ), the repository has a focus on the curation of long-tail data by domain scientists on one hand, but also provides DOI minting services for several global monitoring networks/observatories in geodesy and geophysics and collaborative projects. Furthermore, as Allocating Agent for the International Generic Sample Number (IGSN), the globally unique persistent identifier for physical samples, GFZ is providing IGSN minting services for physical samples. GFZ Data Services increases the interoperability of long-tail data through (1) the provision of comprehensive domain-specific data description via standardised and machine-readable metadata with controlled domain vocabularies. Metadata is (2) complemeted with comprehensive and standardised technical data descriptions or reports; and (3) by embedding the research data in wider context by providing cross-references through Persistent Identifiers (DOI, IGSN, ORCID, Fundref) to related research products (text, data, software) and people or institutions involved. In addition to the task as a research data publisher, GFZ Data Services is the central node for research data management at the GFZ with information on metadata, data formats, the data publication workflow, FAQ, links to different versions of our metadata editor and downloadable data description templates. Specific data publication guidance is complemented by more general information on data management, like a data management roadmap for PhD students.
    Beschreibung: GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Data Management ; Repository
    Sprache: Englisch
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  • 58
    Publikationsdatum: 2022-11-29
    Beschreibung: Die Fachinformationsdienste FID GEO, FID KARTEN und FID MONTAN veranstalteten eine gemeinsame Online-Session für die geowissenschaftlichen Fachreferate. Dabei wurden die einzelnen Fachinformationsdienste und ihre Services präsentiert und es wurde Gelegenheit geben, über zusätzliche Anforderungen an die Dienste aus Sicht der Fachreferate zu sprechen.
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Open Access ; Text Publikation
    Sprache: Deutsch
    Materialart: doc-type:conferenceObject
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  • 59
    Publikationsdatum: 2022-11-29
    Beschreibung: The shift towards Open Science practices is increasingly demanded by science policy. The transition to Open Access for text publications goes hand in hand with a growing demand to make data, scientific software and samples, freely and FAIRly available to the general public. A persistent problem here is the clear and permanent accessibility and re-usability of scientific publications. This development affects both the scientific publication culture as well as the information infrastructures and poses major challenges to the German- based geosciences community. The specialized information service for geosciences (FID GEO) is a service funded by the German Research Foundation (DFG) and supports the cultural change towards Open Access publications. Hereby, FID GEO pursues a holistic approach to Open Science, including scientific literature, data, samples, and scientific software, and aims to promote their interconnection. FID GEO actively provides data and text publishing services through the affiliated repositories GFZ Data Services and GEO-LEOe-docs, as well as an on-demand digitization service of printed geoscientific literature and maps. The focus here is on the services and information systems that ensure permanently available and reliably citable publications of writings and data. Specifically, the service for text publications is provided in the FID GEOs own subject repository GEO-LEOe- docs. The affiliated research data repository GFZ Data Services is available for the publication of research data and scientific software from the earth and environmental sciences. In addition, FID GEO aims to comprehensively inform the German-based geoscientific community about Open Science and FAIR data by bringing the discussions to the individual disciplines through various communication channels. To strengthen the open information culture in the geosciences, FID GEO collaborates with strategic (inter)national initiatives such as NFDI4Earth, COPDESS and OneGeochemistry.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: poster
    Schlagwort(e): ddc:550 ; Open Access
    Sprache: Englisch
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  • 60
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2022-11-29
    Beschreibung: The Berlin Declaration from 2003 was the starting point for Open Access to scholarly publications. Today, however, we speak about Open Science that reaches far beyond Open Access and represents collaborative, transparent and accessible research that includes all kinds of research results: scholarly literature, research data, software, samples, instruments, etc. In addition, efforts such as the FAIR Principles and the Enabling FAIR Data Commitment Statement, combined with increasing demands for machine accessibility to data, have raised user expectations towards the capabilities of research data repositories and datacentres. These repositories are often key partners supporting researchers in fulfilling the new requirements. This presentation will draw the line from major statements and requirements of Open Science, delineate the role of research data repositories as well as major research infrastructures, like the fNFDI4Earth or EPOS (European Plate Observing System) are additional players in making research data accessible in harmonised form.
    Beschreibung: DFG, SUB Göttingen, GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Data ; Open Science
    Sprache: Englisch
    Materialart: doc-type:conferenceObject
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  • 61
    facet.materialart.
    Unbekannt
    Publikationsdatum: 2022-11-29
    Beschreibung: Als DFG-geförderter Service der Niedersächsischen Staats- und Universitätsbibliothek Göttingen (SUB) und des Deutschen GeoForschungsZentrums GFZ unterstützt der Fachinformationsdienst Geowissenschaften (FID GEO) den Wandel in der Forschungs- und Publikationskultur hin zu Open Science. Die freie Zugänglichkeit, aber auch Praktiken wie die korrekte Dokumentation und Verknüpfung verschiedener Forschungsbestandteile und Veröffentlichungsformate (Probenregistrierung, Datenpublikation, Texte, Karten, Software), stehen hier im Fokus. Der FID GEO bietet mit dem von der SUB Göttingen betriebenen Fachrepositorium GEO-LEOe-docs eine sachgerechte Open-Access-Publikation geowissenschaftlicher Werke an. Liegen diese nur gedruckt vor, übernimmt der FID GEO auch die unentgeltliche und professionelle Digitalisierung im Vorfeld der Online-Veröffentlichung. Seit 2021 ist die Telma auf der Startseite von GEO-LEOe-docs als fortlaufende Netzpublikation prominent hervorgehoben. Bereits seit 2018 erscheint sie parallel zum Druck als frei zugängliche Online-Publikation auf GEO-LEOe-docs. Ein großer Teil älterer TELMA-Artikel konnte digitalisiert und ebenfalls online gestellt werden. Die neueren Entwicklungen im FID GEO, darunter die Einbindung von ORCID und fortlaufenden Netzpublikationen im Repositorium, werden vorgestellt. Auch hat sich das jährliche DownloadVolumen von GEO-LEOe-docs in den letzten vier Jahren (2021 gegenüber 2017) verzehnfacht. Dass die Wissenschaft insgesamt besser vorankommt, wenn vorhergehende Forschungsergebnisse den Forschenden umfassender zugänglich sind, versteht sich. Doch auch für Autor*innen ist die frei zugängliche Publikation ihrer Ergebnisse im Open Access von Vorteil, da sie zu einer erhöhten Verbreitung der Veröffentlichungen führt, die folglich auch häufiger zitiert werden. Ebenso profitieren die Journale davon, da sich ihre Reichweite und damit die Beliebtheit der Zeitschrift erhöht. www.fidgeo.de https://e-docs.geo-leo.de/
    Beschreibung: DFG, SUB Göttingen
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Open Access
    Sprache: Deutsch
    Materialart: doc-type:conferenceObject
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  • 62
    Publikationsdatum: 2022-11-29
    Beschreibung: How open is our research? A discussion on the state of Open Science in the field of mineralogy and petrology. Vortrag bei der Arbeitsgruppe Mineralogie+Petrologie der Uni Potsdam, 29.04.2022 A brief look at current trends toward an open science with a focused look at the state of the art in mineralogy and petrology. Followed by a discussion on how research in mineralogy and petrology can become more open.
    Beschreibung: DFG, GFZ Potsdam
    Beschreibung: presentation
    Schlagwort(e): ddc:550 ; Open Access
    Sprache: Englisch
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  • 63
    Publikationsdatum: 2023-01-26
    Beschreibung: We present the first‐generation full‐waveform tomographic model (SinoScope 1.0) for the crust‐mantle structure beneath China and adjacent regions. The three‐component seismograms from 410 earthquakes recorded at 2,427 stations are employed in iterative gradient‐based inversions for three successively broadened period bands of 70–120 s, 50–120 s, and 30–120 s. Synthetic seismograms were computed using GPU‐accelerated spectral‐element simulations of seismic wave propagation in 3‐D anelastic models, and Fréchet derivatives were calculated based on an adjoint‐state method facilitated by a checkpointing algorithm. The inversion involved 352 iterations, which required 18,600 wavefield simulations. SinoScope 1.0 is described in terms of isotropic P‐wave (VP), horizontally and vertically polarized S‐wave velocities (VSH and VSV), and mass density (ρ), which are independently constrained with the same data set coupled with a stochastic L‐BFGS quasi‐Newton optimization scheme. It systematically reduced differences between observed and synthetic full‐length seismograms. We performed a detailed resolution analysis by repairing input random parametric perturbations, indicating that resolution lengths can approach the half propagated wavelength within the well‐covered areas. SinoScope 1.0 reveals strong lateral heterogeneities in the lithosphere, and features correlate well with geological observations, such as sedimentary basins, Holocene volcanoes, Tibetan Plateau, Philippine Sea Plate, and various tectonic units. The asthenosphere lies below the lithosphere beneath East and Southeast Asia, bounded by subduction trenches and cratonic blocks. Furthermore, we observe an enhanced image of well‐known slabs along strongly curved subduction zones, which do not exist in the initial model.
    Beschreibung: Plain Language Summary: Subduction (a geological process where the oceanic lithosphere descends into the Earth's mantle at convergent boundaries) has been the dominant plate‐tectonic process in the broad Asian region since the Mesozoic (252–66 million years ago). The nature of cold subducting slabs and hot mantle flows can record and affect the tectonic evolution of the overriding lithospheric plates. In this study, we conduct the full waveform inversion on a large data set to image the crust‐mantle structure of this region. The computationally demanding simulations were performed on two of the world's fastest supercomputing facilities. Our new model delivers seismic illumination of the region at unprecedented resolution and exhibits sharper and more detailed shear wave velocity structure in the lithosphere with greatly improved correlations with surface tectonic units compared to previous tomographic models. The narrow low‐velocity layer (generally referred to as asthenosphere) below the lithosphere is present beneath East and Southeast Asia, bounded by subduction trenches and cratonic blocks. The continuous and intense subduction processes are responsible for high‐velocity anomalous bodies in the mantle and the formation of the asthenosphere mentioned above.
    Beschreibung: Key Points: We construct a new full‐waveform tomographic model of the broad Asian region for 30–120 s period via adjoint and spectral‐element methods. The resolution analysis shows reasonably good resolution in the frequency band of interest and limited trade‐offs between model parameters. Our model shed new light on the subsurface behavior of cold subducting slabs & hot mantle flows and their relation to the overriding plates.
    Beschreibung: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Beschreibung: Swiss National Supercomputing Center
    Beschreibung: European Unions Horizon 2020
    Beschreibung: The Collaborative Seismic Earth Model
    Beschreibung: National Natural Science Foundation of China
    Beschreibung: Korea Meteorological Administration Research and Development Program
    Beschreibung: Korean Government
    Beschreibung: Ministry of Education
    Beschreibung: https://doi.org/10.5281/zenodo.6597380
    Schlagwort(e): ddc:550 ; Asia ; mantle ; lithosphere ; seismic tomography ; computional seismology
    Sprache: Englisch
    Materialart: doc-type:article
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  • 64
    Publikationsdatum: 2023-01-27
    Beschreibung: Abrupt fluid emissions from shallow marine sediments pose a threat to seafloor installations like wind farms and offshore cables. Quantifying such fluid emissions and linking pockmarks, the seafloor manifestations of fluid escape, to flow in the sub‐seafloor remains notoriously difficult due to an incomplete understanding of the underlying physical processes. Here, using a compositional multi‐phase flow model, we test plausible gas sources for pockmarks in the south‐eastern North Sea, which recent observations suggest have formed in response to major storms. We find that the mobilization of pre‐existing gas pockets is unlikely because free gas, due to its high compressibility, damps the propagation of storm‐induced pressure changes deeper into the subsurface. Rather, our results point to spontaneous appearance of a free gas phase via storm‐induced gas exsolution from pore fluids. This mechanism is primarily driven by the pressure‐sensitivity of gas solubility, and the appearance of free gas is largely confined to sediments in the vicinity of the seafloor. We show that in highly permeable sediments containing gas‐rich pore fluids, wave‐induced pressure changes result in the appearance of a persistent gas phase. This suggests that seafloor fluid escape structures are not always proxies for overpressured shallow gas and that periodic seafloor pressure changes can induce persistent free gas phase to spontaneously appear.
    Beschreibung: Plain Language Summary: Thousands of pockmarks, circular depressions in the seafloor, were reported in North Sea, presumably formed in response to wave motions during major storms. It has been hypothesized that these pockmarks formed as pre‐existing shallow free‐gas pockets were mobilized by pressure changes of the waves. However, mechanisms that could have mobilized free‐gas are not yet constrained. Moreover, large scale free‐gas accumulations have not been reported in this region, and therefore, commonly invoked mechanisms like tensile failure and breaching of capillary seals are hard to justify as they rely on the presence of pre‐existing gas pockets. Here, through modeling studies, we tackle the question of the source of the observed free‐gas. Our study consists of two parts: First, assuming that some hitherto unknown shallow free‐gas pocket is indeed present, we test whether storm‐induced pressure changes could breach capillary seals. We find that free‐gas damps pressure changes due to its high compressibility, making the mobilization of pre‐existing gas unlikely. In the second part, we propose an alternative mechanism where free‐gas spontaneously appears due to exsolution from pore‐fluids. We test the feasibility of this mechanism and show how periodic pressure changes can lead to a persistent gas phase, that could explain the elusive gas source linked to these pockmarks.
    Beschreibung: Key Points: Storm‐induced pressure changes can lead to spontaneous appearance of free gas phase near the seafloor. This process is driven by pressure‐sensitive phase instabilities. This mechanism could help explain elusive gas sources in recently observed pockmarks in the North Sea.
    Beschreibung: Aker BP (AkerBP) http://dx.doi.org/10.13039/100016998
    Beschreibung: Deutsche Forschungsgemeinschaft, DFG
    Schlagwort(e): ddc:550 ; pockmarks ; storm related pockmarks ; spontaneous free gas ; gas source ; modeling
    Sprache: Englisch
    Materialart: doc-type:article
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  • 65
    Publikationsdatum: 2023-11-24
    Beschreibung: This GGR Bibliographic Review is a survey of approximately 5200 geoanalytical publications for the year 2021. Selected articles, numbering over 340, containing measurement results for relevant geological and environmental reference materials are listed with individual summaries of target analytes, relevant reference materials and producers. A brief summary of a selection of these publications is included that highlights notable developments in geoanalytical studies, newly developed or characterised RMs, and new datasets of established reference materials that have been re‐analysed using improved or state‐of‐the‐art measurement techniques.
    Beschreibung: Key Points: Literature review of 5200 geoanalytical publications for the year 2021. 344 selected articles with summaries of target analytes, relevant reference materials and producers. Selected publications include data obtained by new analytical developments and improved analytical protocols for established RMs, and identifies recently developed RMs for specific scientific topics.
    Beschreibung: http://georem.mpch-mainz.gwdg.de/
    Schlagwort(e): ddc:550 ; review ; analytical geochemistry ; geochemical reference materials ; reference material data ; GeoReM database ; environmental reference materials
    Sprache: Englisch
    Materialart: doc-type:article
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  • 66
    Publikationsdatum: 2021-07-04
    Beschreibung: Geological evidence indicates large continental‐scale Antarctic ice volume variations during the early and mid‐Miocene. On million‐year timescales, these variations can largely be explained by equilibrium Antarctic ice sheet (AIS) simulations. In contrast, on shorter orbital timescales, the AIS needs not be in equilibrium with the forcing and ice volume variations may be substantially different. Here, we introduce a conceptual model, based on ice dynamical model results, to investigate the difference between transient variability and equilibrium differences of the Miocene AIS. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. We show that phases of concurrent ice volume increase and rising CO2 levels are possible, even though the equilibrium ice volume decreases monotonically with CO2. When the AIS volume is out of equilibrium with the forcing climate, the ice sheet can still be adapting to a relatively large equilibrium size, although CO2 is rising after a phase of decrease. A delayed response of Antarctic ice volume to (covarying) solar insolation and CO2 concentrations can cause discrepancies between Miocene solar insolation and benthic δ18O variability. Increasing forcing frequency leads to a larger disequilibrium and consequently larger CO2‐ice volume phase differences. Furthermore, an amplified forcing amplitude causes larger amplitude ice volume variability, because the growth and decay rates depend on the forcing. It also leads to a reduced average ice volume, resulting from the growth rates generally being smaller than the decay rates.
    Beschreibung: Plain Language Summary: The early and mid‐Miocene (23–14 Myr ago) was the last period in Earth's history when the Antarctic ice sheet (AIS) size changed between being almost completely vanished and its current magnitude. So far, ice modelers have tried explaining this large‐scale AIS variability using steady‐state experiments, in which the final ice volume is in equilibrium with the forcing climate. In these simulations, phases of simultaneous ice sheet growth and CO2 increase have to be caused by increased precipitation outweighing increased melt in a warmer climate. Conversely, simultaneous ice sheet decay and CO2 decrease must be due to decreased precipitation exceeding decreased melt. Here, we provide an alternative explanation for these phases, based on the notion that the slowly evolving AIS is not in equilibrium with the forcing climate. In our model, an ice sheet will grow (shrink) by a specific rate when it is smaller (larger) than its equilibrium size. The AIS can then still be adapting to a relatively large equilibrium size, when CO2 is already increasing again after an initial drop. It can also continue decaying after a reversal from rising to sinking CO2 levels. Our results serve to aid the interpretation of Miocene geological oxygen isotope data.
    Beschreibung: Key Points: Concurrent Antarctic ice sheet growth and CO2 level rise can occur because of disequilibrium between ice volume and climate. The disequilibrium and CO2‐ice volume phase differences grow with increasing frequency of the forcing. Larger amplitude CO2 variability causes larger amplitude ice volume variability and a smaller average ice sheet.
    Schlagwort(e): 551 ; Miocene ; Antarctica ; ice sheet ; sea level ; carbon dioxide
    Materialart: article
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  • 67
    Publikationsdatum: 2021-07-05
    Beschreibung: Defining effective measures to reduce nitrate pollution in heterogeneous mesoscale catchments remains challenging when based on concentration measurements at the outlet only. One reason for this is our limited understanding of the subcatchment contributions to nitrate export and their importance at different time scales. While upstream subcatchments often disproportionally contribute to runoff generation and in turn to nutrient export, agricultural areas (which are typically found in downstream lowlands) are known to be a major source of nitrate pollution. To examine the interplay of different subcatchments, we analyzed seasonal long‐term trends and event dynamics of nitrate concentrations, loads, and the concentration–discharge relationship in three nested catchments within the Selke catchment (456 km2), Germany. The upstream subcatchments (40.4% of total catchment area, 34.5% of N input) had short transit times and dynamic concentration–discharge relationships with elevated nitrate concentrations during wet seasons and events. Consequently, the upstream subcatchments dominated nitrate export during high flow and disproportionally contributed to overall annual nitrate loads at the outlet (64.2%). The downstream subcatchment was characterized by higher N input, longer transit times, and relatively constant nitrate concentrations between seasons, dominating nitrate export during low‐flow periods. Neglecting the disproportional role of upstream subcatchments for temporally elevated nitrate concentrations and net annual loads can lead to an overestimation of the role of agricultural lowlands. Nonetheless, constantly high concentrations from nitrate legacies pose a long‐term threat to water quality in agricultural lowlands. This knowledge is crucial for an effective and site‐specific water quality management.
    Beschreibung: Plain Language Summary: To efficiently remove nitrate pollution, we need to understand how it is transported, mobilized, and stored within large and heterogeneous catchments. Previous studies have shown that upstream catchments often have a disproportional impact on nutrient export, while agriculture (a major nitrate source) is often located in downstream lowlands. To understand which parts of a catchment contribute most to nitrate export and when, we analyzed long‐term (1983–2016) and high‐frequency (2010–2016) data in the Selke catchment (Germany) at three locations. The mountainous upstream part dominated nitrate transport during winter, spring, and rain events. It had a surprisingly high contribution to annual nitrate loads. The agricultural downstream part of the catchment dominated nitrate export during summer and autumn, with relatively constant concentrations between seasons. Here, nitrogen inputs needed more than a decade to travel through the subsurface of the catchment, which causes a time lag between measures to reduce nitrate pollution and their measurable effect. The resulting storage of nitrate in the groundwater threatens drinking water quality for decades to come. While the role of agricultural lowlands for nitrate export can be overestimated if neglecting the disproportional role of upstream subcatchments, their impact poses a long‐term threat to water quality.
    Beschreibung: Key Points: Analyzing the CQ relationship across time scales allows the disentanglement of the impact of catchment heterogeneity on nitrate export. Mountainous upstream subcatchments can dominate nitrate export during high flows and disproportionally contribute to nitrate loads. Agricultural downstream subcatchments can dominate nitrate export during low flow and pose a long‐term threat to water quality.
    Beschreibung: DFG collaborative research center (SFB) 1253 “CAMPOS”
    Beschreibung: Helmholtz Research Program, Integrated Project “Water and Matter Flux Dynamics in Catchments”
    Beschreibung: Initiative and Networking Fund of the Helmholtz Association through the project Advanced Earth System Modelling Capacity (ESM)
    Schlagwort(e): 551 ; concentration–discharge relationships ; event dynamics ; long‐term trends ; nitrate ; nutrient export ; water quality
    Materialart: article
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  • 68
    Publikationsdatum: 2021-07-01
    Beschreibung: The ~0.2 km3 Eibsee rock avalanche impacted Paleolake Eibsee and completely displaced its waters. This study analyses the lake impact and the consequences, and the catchment response to the landslide. A quasi‐3D seismic reflection survey, four sediment cores from modern Lake Eibsee, reaching far down into the rock avalanche mass, nine radiocarbon ages, and geomorphic analysis allow us to distinguish the main rock avalanche event from a secondary debris avalanche and debris flow. The highly fluidized debris avalanche formed a megaturbidite and multiple swashes that are recorded in the lake sediments. The new calibrated age for the Eibsee rock avalanche of ~4080–3970 cal yr BP indicates a coincidence with rockslides in the Fernpass cluster and subaquatic landslides in Lake Piburg and Lake Plansee, and raises the possibility that a large regional earthquake triggered these events. We document a complex history of erosion and sedimentation in Lake Eibsee, and demonstrate how the catchment response and rebirth of the lake are revealed through the complementary application of geophysics, sedimentology, radiocarbon dating, and geomorphology. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: Sedimentological, geophysical and geomorphological investigation in and around Lake Eibsee allows to decipher three rock‐slope failures from Mount Zugspitze: (i) the Eibsee rock avalanche ~4000 cal yr BP; (ii) a debris avalanche in the aftermath; and (iii) a large debris flow ~3740 cal yr BP. The Eibsee rock avalanche was re‐dated to a refined age of 4089–3876 cal yr BP. The coincidence with major events in the Fernpass rockslide cluster increases the likelihood of a prehistoric earthquake trigger.
    Beschreibung: Studienstiftung des Deutschen Volkes e.V. (German National Academic Foundation): http://dx.doi.org/10.13039/501100004350
    Beschreibung: British Society for Geomorphology http://dx.doi.org/10.13039/100010165
    Schlagwort(e): 551 ; rock avalanche ; lake impact ; lake sediments ; catchment response ; progressive slope failure ; recurrence rates ; prehistoric earthquake ; Fernpass rockslide cluster
    Materialart: article
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  • 69
    Publikationsdatum: 2021-04-14
    Beschreibung: The continuing development of analytical methods for investigating sedimentary records calls for iterative re‐examination of existing data sets obtained on loess‐palaeosol sequences (LPS) as archives of palaeoenvironmental change. Here, we re‐investigate two LPS (Hecklingen, Zilly) in the northern Harz foreland, Germany, being of interest due to their proximity to the Scandinavian Ice Sheet (SIS) and the position between oceanic climatic influence further west and continental influence towards the east. First, we established new quartz OSL and polymineral IRSL chronologies. Both methods show concordant ages in the upper part of the Hecklingen profile (~20–40 ka), but in the lower part IRSL underestimates OSL ages by up to ~15 ka for the period 40–60 ka. Interpretations hence refer to the OSL data set. Second, we applied Bayesian age‐depth modelling to data sets from Hecklingen to resolve inversions in the original ages, also reducing averaged 1σ uncertainty by ~19% (OSL) and ~12% (IRSL). Modelled chronologies point out phases of increased (MIS 2, early MIS 3) and reduced (middle and late MIS 3) sedimentation, but interpretation of numerical rates is problematic because of intense erosion and slope wash particularly during MIS 3. Finally, previously obtained grain‐size data were re‐investigated by end member modelling analyses. Three fundamental grain‐size distributions (loadings) explain the measured data sets and offer information on intensity and – combined with modelled OSL ages – timing of geomorphic processes. We interpret the loadings to represent (i) primary loess accumulation, (ii) postdepositional pedogenesis and/or input of aeolian fine fractions, and (iii) input of coarse aeolian material and/or slope wash. The applied modelling tools facilitate detailed understanding of site‐formation through time, allowing us to correlate a strong peak in mean grain size at ~26–24 ka to the maximum extent of the SIS and increased influence of easterly winds.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; Harz foreland ; loess-palaeosol sequences ; luminescence ages ; Bayesian age-depth modelling ; sedimentation rates
    Materialart: article
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  • 70
    Publikationsdatum: 2021-04-21
    Beschreibung: Ice shelves around Antarctica can provide back stress for outlet glaciers and control ice sheet mass loss. They often contain narrow bands of thin ice termed ice shelf channels. Ice shelf channel morphology can be interpreted through surface depressions and exhibits junctions and deflections from flowlines. Using ice flow modeling and radar, we investigate ice shelf channels in the Roi Baudouin Ice Shelf. These are aligned obliquely to the prevailing easterly winds. In the shallow radar stratigraphy, syncline and anticline stacks occur beneath the upwind and downwind side, respectively. The structures are horizontally and vertically coherent, except near an ice shelf channel junction where patterns change structurally with depth. Deeper layers truncate near basal incisions. Using ice flow modeling, we show that the stratigraphy is ∼9 times more sensitive to atmospheric variability than to oceanic variability. This is due to the continual adjustment toward flotation. We propose that syncline‐anticline pairs in the shallow stratigraphy are caused by preferential snow deposition on the windward side and wind erosion at the downwind side. This drives downwind deflection of ice shelf channels of several meters per year. The depth variable structures indicate formation of an ice shelf channel junction by basal melting. We conclude that many ice shelf channels are seeded at the grounding line. Their morphology farther seaward is shaped on different length scales by ice dynamics, the ocean, and the atmosphere. These processes act on finer (subkilometer) scales than are captured by most ice, atmosphere, and ocean models, yet the dynamics of ice shelf channels may have broader implications for ice shelf stability.
    Beschreibung: Plain Language Summary Ice flows from Antarctica's interior toward the coast. At the contact point between ice and ocean, the ice becomes afloat and forms fast‐flowing ice shelves. Snowfall continuously accumulates at the ice shelf surface, and at the ice shelf bottom the relatively warm ocean water can melt ice from below. Ice shelves sometimes exhibit a network of surface depressions resembling a river network. At the base, the depressions are accompanied by large incisions termed ice shelf channels. Using radar as a tool for echolocation, we investigate how the shape of this network is formed. We find that snow preferentially collects in the upwind side of the surface depressions. This makes ice shelf channels move to the downwind side. We also find that ice shelf channels can form junctions through localized ocean melting. This is important because it helps us to better understand how the Antarctic ice sheet interacts with the surrounding ocean.
    Beschreibung: Key Points The radar stratigraphy in ice shelves is 9 times more sensitive to variability in snow deposition than to variability in basal melting Some ice shelf channels at Roi Baudouin Ice Shelf deflect from flowlines; the radar stratigraphy reflects related processes Variable snow deposition causes slow deflection, and basal melting can form ice shelf channel junctions far from the grounding line
    Beschreibung: InBev Baillet Latour Antarctica Fellowship
    Beschreibung: Belgian Science Policy Office http://dx.doi.org/10.13039/501100002749
    Beschreibung: DFG Emmy Noether
    Beschreibung: Academy of Finland http://dx.doi.org/10.13039/501100002341
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: “Antarctic Research with comparative investigations in Arctic ice areas”
    Beschreibung: Academy of Finnland
    Beschreibung: Belgium Science Policy Office
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: InBev Baillet Latour Antarctica Fellowship
    Schlagwort(e): 551 ; glaciology ; geophysics ; Antarctica ; ice shelves ; ice‐ocean interaction ; ice shelf channels
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  • 71
    Publikationsdatum: 2021-07-04
    Beschreibung: Sediment budgeting concepts serve as quantification tools to decipher the erosion and accumulation processes within a catchment and help to understand these relocation processes through time. While sediment budgets are widely used in geomorphological catchment‐based studies, such quantification approaches are rarely applied in geoarchaeological studies. The case of Charlemagne's summit canal (also known as Fossa Carolina) and its erosional collapse provides an example for which we can use this geomorphological concept and understand the abandonment of the Carolingian construction site. The Fossa Carolina is one of the largest hydro‐engineering projects in Medieval Europe. It is situated in Southern Franconia (48.9876°N, 10.9267°E; Bavaria, southern Germany) between the Altmühl and Swabian Rezat rivers. It should have bridged the Central European watershed and connected the Rhine–Main and Danube river systems. According to our dendrochronological analyses and historical sources, the excavation and construction of the Carolingian canal took place in AD 792 and 793. Contemporary written sources describe an intense backfill of excavated sediment in autumn AD 793. This short‐term erosion event has been proposed as the principal reason for the collapse and abandonment of the hydro‐engineering project. We use subsurface data (drillings, archaeological excavations, and direct‐push sensing) and geospatial data (a LiDAR digital terrain model (DTM), a pre‐modern DTM, and a 3D model of the Fossa Carolina] for the identification and sediment budgeting of the backfills. Dendrochronological findings and radiocarbon ages of macro remains within the backfills give clear evidence for the erosional collapse of the canal project during or directly after the construction period. Moreover, our quantification approach allows the detection of the major sedimentary collapse zone. The exceedance of the manpower tipping point may have caused the abandonment of the entire construction site. The spatial distribution of the dendrochronological results indicates a north–south direction of the early medieval construction progress. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: The sediment budgeting concept as erosion and accumulation quantification tool helps in understanding the abrupt backfilling of excavated material in the construction pit, which may have forced the abandonment of the Carolingian canal in southern Germany at the end of the year AD 793. The backfill sediments could be dated precisely through radiocarbon dating of macro remains and dendrochronology of excavated timbers. These timbers recovered in three different archaeological excavation trenches reveal a Carolingian construction progress from North to South.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; Sediment budgeting ; Geomorphological modelling ; Backfill processes ; Geoarchaeology ; Fossa Carolina ; Early Middle Ages ; South Germany
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  • 72
    Publikationsdatum: 2021-07-04
    Beschreibung: This study suggests a stochastic Bayesian approach for calibrating and validating morphodynamic sediment transport models and for quantifying parametric uncertainties in order to alleviate limitations of conventional (manual, deterministic) calibration procedures. The applicability of our method is shown for a large‐scale (11.0 km) and time‐demanding (9.14 hr for the period 2002–2013) 2‐D morphodynamic sediment transport model of the Lower River Salzach and for three most sensitive input parameters (critical Shields parameter, grain roughness, and grain size distribution). Since Bayesian methods require a significant number of simulation runs, this work proposes to construct a surrogate model, here with the arbitrary polynomial chaos technique. The surrogate model is constructed from a limited set of runs (n=20) of the full complex sediment transport model. Then, Monte Carlo‐based techniques for Bayesian calibration are used with the surrogate model (105 realizations in 4 hr). The results demonstrate that following Bayesian principles and iterative Bayesian updating of the surrogate model (10 iterations) enables to identify the most probable ranges of the three calibration parameters. Model verification based on the maximum a posteriori parameter combination indicates that the surrogate model accurately replicates the morphodynamic behavior of the sediment transport model for both calibration (RMSE = 0.31 m) and validation (RMSE = 0.42 m). Furthermore, it is shown that the surrogate model is highly effective in lowering the total computational time for Bayesian calibration, validation, and uncertainty analysis. As a whole, this provides more realistic calibration and validation of morphodynamic sediment transport models with quantified uncertainty in less time compared to conventional calibration procedures.
    Beschreibung: Key Points: We reduce a time‐demanding sediment transport model with a surrogate technique based on the arbitrary polynomial chaos expansion (aPC). Bayesian model calibration and validation in a fraction of computational time compared to conventional (manual, deterministic) methods. We achieve a more realistic calibration, a more successful validation, and valuable information in the form of uncertainty intervals.
    Beschreibung: German Research Foundation (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; sediment transport modeling ; Lower River Salzach ; surrogate model ; arbitrary polynomial chaos expansion ; uncertainty analysis ; Bayesian updating
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  • 73
    Publikationsdatum: 2021-06-22
    Beschreibung: The contribution of sediments to nutrient cycling of the coastal North Sea is strongly controlled by the intensity of fluxes across the sediment water interface. Pore‐water advection is one major exchange mechanism that is well described by models, as it is determined by physical parameters. In contrast, biotransport (i.e., bioirrigation, bioturbation) as the other major transport mechanism is much more complex. Observational data reflecting biotransport, from the German Bight for example, is scarce. We sampled the major sediment provinces of the German Bight repeatedly over the years from 2013 to 2019. By employing ex situ whole core incubations, we established the seasonal and spatial variability of macrofauna‐sustained benthic fluxes of oxygen and nutrients. A multivariate, partial least squares analysis identified faunal activity, in specifically bioturbation and bioirrigation, alongside temperature, as the most important drivers of oxygen and nutrient fluxes. Their combined effect explained 63% of the observed variability in oxygen fluxes, and 36–48% of variability in nutrient fluxes. Additional 10% of the observed variability of fluxes were explained by sediment type and the availability of plankton biomass. Based on our extrapolation by sediment provinces, we conclude that pore‐water advection and macrofaunal activity contributed equally to the total benthic oxygen uptake in the German Bight.
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): 551 ; southern North Sea ; coastal sediments ; macrofauna ; bioturbation ; bioirrigation ; organic matter turnover
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  • 74
    Publikationsdatum: 2021-07-21
    Beschreibung: Ultraslow spreading ridges form the slowest divergent plate boundaries and exhibit distinct spreading processes in volcanically active magmatic sections and intervening amagmatic sections. Local seismicity studies of ultraslow spreading ridges until now cover only parts of segments and give insight into spreading processes at confined locations. Here, we present a microseismicity data set that allows to study spreading processes on the scale of entire segments. Our network of 26 ocean bottom seismometers covered around 160 km along axis of the ultraslow spreading Knipovich Ridge in the Greenland Sea and recorded earthquakes for a period of about 1 year. We find seismicity varying distinctly along‐axis. The maximum earthquake depths shallow over distances of 70 km toward the Logachev volcanic center. Here, swarm activity occurs in an otherwise aseismic zone. Melts may thus be guided along the subparallel topography of the lithosphere‐asthenosphere boundary toward major volcanic centers explaining the uneven along‐axis melt distribution typical for ultraslow ridges. Absence of shallow seismicity in the upper 8 km of the lithosphere with a band of deep seismicity underneath offsets presumably melt‐poor regions from magma richer sections. Aseismic deformation in these regions may indicate weakening of mantle rocks by alteration. We do not find obvious indications for major detachment faulting that characterizes magma‐poor spreading at some ultraslow spreading segments. The highly oblique spreading of Knipovich Ridge may be the reason for a fine‐scale segmentation of the seismic activity with zones of weak seismicity possibly indicating transform motion on short obliquely oriented faults.
    Beschreibung: Plain Language Summary: At mid‐ocean spreading ridges, tectonic plates drift apart and new seafloor is built by upwelling magma. The slowest spreading ridges do not receive enough magma to build new seafloor along the entire ridge. Rather, they show widely spaced volcanic centers with magma‐poor areas in‐between. The study of small earthquakes with seismometers placed on the seafloor has greatly helped to understand how new seafloor forms. Since such studies require substantial logistic effort, only confined ridge sections have been studied and spreading processes operating at segment‐scale remain poorly understood. In this study, we present for the first time observations of earthquakes covering several segments and one major volcanic center along the Knipovich Ridge in the Greenland Sea. Underneath the volcano, earthquake swarms and a gap in seismicity indicate recent magmatic activity. The maximum depth of earthquakes marks the thickness of the mechanically strong lithosphere. It shallows over 70 km toward the volcano such that melts can be channeled over large distances to the prominent volcanoes. Magma‐poor regions have deep earthquakes but do not show earthquake activity in the upper 8 km. We suppose that water reacts with the mantle rocks that become too weak to break in earthquakes.
    Beschreibung: Key Points: Magma‐poor sections are distinguished from magma‐rich sections by deeper hypocenters and an absence of shallow seismicity. Shallowing maximum earthquake depths over distances of 70 km suggest along‐axis melt focusing toward major volcanic centers. Major detachment faults on the highly oblique spreading Knipovich Ridge were not obvious in the observed seismicity.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: Helmholtz Excellence Network POSY at the Alfred Wegener Institute
    Beschreibung: Ministry of Science and Higher Education of Poland
    Schlagwort(e): 551 ; amagmatic ; Knipovich Ridge ; mid‐ocean ridge ; segmentation ; seismicity ; ultraslow spreading
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  • 75
    Publikationsdatum: 2021-07-04
    Beschreibung: First reported in the 1960s, offshore freshened groundwater (OFG) has now been documented in most continental margins around the world. In this review we compile a database documenting OFG occurrences and analyze it to establish the general characteristics and controlling factors. We also assess methods used to map and characterize OFG, identify major knowledge gaps, and propose strategies to address them. OFG has a global volume of 1 × 106 km3; it predominantly occurs within 55 km of the coast and down to a water depth of 100 m. OFG is mainly hosted within siliciclastic aquifers on passive margins and recharged by meteoric water during Pleistocene sea level lowstands. Key factors influencing OFG distribution are topography‐driven flow, salinization via haline convection, permeability contrasts, and the continuity/connectivity of permeable and confining strata. Geochemical and stable isotope measurements of pore waters from boreholes have provided insights into OFG emplacement mechanisms, while recent advances in seismic reflection profiling, electromagnetic surveying, and numerical models have improved our understanding of OFG geometry and controls. Key knowledge gaps, such as the extent and function of OFG, and the timing of their emplacement, can be addressed by the application of isotopic age tracers, joint inversion of electromagnetic and seismic reflection data, and development of three‐dimensional hydrological models. We show that such advances, combined with site‐specific modeling, are necessary to assess the potential use of OFG as an unconventional source of water and its role in sub‐seafloor geomicrobiology.
    Beschreibung: Plain Language Summary: This review paper considers offshore freshened groundwater (OFG), which is water hosted in sediments and rocks below the seafloor, with a total dissolved solid concentration lower than seawater. We have compiled 〉300 records to demonstrate that freshened groundwater occurs offshore on most continents around the world and has a global volume of 1 × 106 km3. The majority of OFG was deposited when sea level was lower than today and is hosted in sandy sub‐seafloor layers that are located within 55 km of coasts in water depths less than 100 m. We present a range of geochemical, geophysical, and modeling approaches that have successfully been used to investigate OFG systems. We also propose approaches to address key scientific questions related to OFG, including whether it may be used as an unconventional source of potable water in coastal areas.
    Beschreibung: Key Points: Most known OFG is located at water depths of 〈100 m within 55 km of the coast, hosted in siliciclastic aquifers in passive margins. Key gaps in knowledge include the extent and function of OFG systems, as well as the mechanism and timing of emplacement. Isotopic tracers, jointly inverted geophysical data and 3‐D hydrological models can help address these knowledge gaps.
    Beschreibung: EC | H2020 | H2020 Priority Excellent Science | H2020 European Research Council (ERC) http://dx.doi.org/10.13039/100010663
    Beschreibung: National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001
    Schlagwort(e): 551 ; offshore freshened groundwater ; continental margin ; marine hydrogeology ; geochemistry ; geophysics ; modeling
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  • 76
    Publikationsdatum: 2021-07-01
    Beschreibung: Rock avalanches destroy and reshape landscapes in only a few minutes and are among the most hazardous processes on Earth. The surface morphology of rock avalanche deposits and the interaction with the underlying material are crucial for runout properties and reach. Water within the travel path is displaced, producing large impact waves and reducing friction, leading to long runouts. We hypothesize that the 0.2 km3 Holocene Eibsee rock avalanche from Mount Zugspitze in the Bavarian Alps overran and destroyed Paleolake Eibsee and left a unique sedimentological legacy of processes active during the landslide. We captured 9.5 km of electrical resistivity tomography (ERT) profiles across the rock avalanche deposits, with up to 120 m penetration depth and more than 34 000 datum points. The ERT profiles reveal up to ~50 m thick landslide debris, locally covering up to ~30 m of rock debris with entrained fine‐grained sediments on top of isolated remnants of decametre‐wide paleolake sediments. The ERT profiles allow us to infer processes involved in the interaction of the rock avalanche with bedrock, lake sediments, and morainal sediments, including shearing, bulging, and bulldozing. Complementary data from drilling, a gravel pit exposure, laboratory tests, and geomorphic features were used for ERT calibration. Sediments overrun by the rock avalanche show water‐escape structures. Based on all of these datasets, we reconstructed both position and size of the paleolake prior to the catastrophic event. Our reconstruction of the event contributes to process an understanding of the rock avalanche and future modelling and hazard assessment. Here we show how integrated geomorphic, geophysical, and sedimentological approaches can provide detailed insights into the impact of a rock avalanche on a lake. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: The Eibsee rock avalanche detached from Mount Zugspitze and impacted and destroyed Paleolake Eibsee. Paleolake Eibsee was larger than modern Lake Eibsee; the rock avalanche deposit covers the northern half of the paleolake. The complementary application of geomorphology, electrical resistivity tomography (ERT) and sedimentology allows for ERT calibration at seven different sites, where materials (rock avalanche, bedrock, lake clay, mixed sediments) and effects of the impact (bulldozing, bulging, overriding of secondary lobes, splashing of boulders) can be distinguished.
    Beschreibung: Studienstiftung des Deutschen Volkes e.V. (German National Academic Foundation): http://dx.doi.org/10.13039/501100004350
    Schlagwort(e): 551 ; rock avalanche ; runout ; lake impact ; paleolake reconstruction ; ERT calibration ; water‐escape structures ; Northern Calcareous Alps ; Eibsee ; Zugspitze
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  • 77
    Publikationsdatum: 2021-07-05
    Beschreibung: Storm events lead to agricultural and urban runoff, to mobilization of contaminated particulate matter, and to input from combined sewer overflows into rivers. We conducted time‐resolved sampling during a storm event at the Ammer River, southwest Germany, which is representative of small river systems in densely populated areas with a temperate climate. Suspended particulate matter (SPM) and water from 2 sampling sites were separately analyzed by a multi‐analyte liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for 97 environmentally relevant organic micropollutants and with 2 in vitro bioassays. Oxidative stress response (AREc32) may become activated by various stressors covering a broad range of physicochemical properties and induction of aryl hydrocarbon receptor–chemical‐activated luciferase gene expression (AhR‐CALUX) by hydrophobic compounds such as dioxins and dioxin‐like molecules. Compound numbers, concentrations, their mass fluxes, and associated effect fluxes increased substantially during the storm event. Micropollutants detected in water and on SPM pointed toward inputs from combined sewer overflow (e.g., caffeine, paracetamol), urban runoff (e.g., mecoprop, terbutryn), and agricultural areas (e.g., azoxystrobin, bentazone). Particle‐facilitated transport of triphenylphosphate and tris(1‐chloro‐2‐propyl) phosphate accounted for up to 34 and 33% of the total mass flux even though SPM concentrations were 〈1 g L–1. Effect fluxes attributed to SPM were similar or higher than in the water phase. The important role of SPM‐bound transport emphasizes the need to consider not only concentrations but also mass and effect fluxes for surface water quality assessment and wastewater/stormwater treatment options. Environ Toxicol Chem 2021;40:88–99. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; Storm event ; Organic micropollutants ; Chemical analysis ; In vitro bioassays ; Water quality
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  • 78
    Publikationsdatum: 2021-07-01
    Beschreibung: Strain localization in the lithosphere and the formation, evolution, and maintenance of resulting plate boundaries play a crucial role in plate tectonics and thermo‐chemical mantle convection. Previously activated lithospheric deformation zones often appear to maintain a “memory” of weakening, leading to tectonic inheritance within plate reorganizations including the Wilson cycle. Different mechanisms have been proposed to explain such strain localization, but it remains unclear which operates on what spatio‐temporal scales, and how to best incorporate them in large‐scale mantle convection models. Here, we analyze two candidates, (1), grain‐size sensitive rheology and, (2), damage‐style parameterizations of yield, stress which are sometimes used to approximate the former. Grain‐size reduction due to dynamic recrystallization can drive localization in the ductile domain, and grain growth provides a time‐dependent rheological hardening component potentially enabling the preservation of rheological heterogeneities. We compare the dynamic weakening and hardening effects as well as the timescales of strength evolution for a composite rheology including grain‐size dynamics with a pseudo‐plastic rheology including damage‐ (or “strain”‐) dependent weakening. We explore the implications of different proposed grain‐size evolution laws, and test to which extent strain‐dependent rheologies can mimic the weakening and hardening effects of the more complex micro‐physical behavior. Such an analysis helps to better understand the parallels and differences between various strain‐localization modeling approaches used in different tectonics and geodynamics communities. More importantly, our results contribute to efforts to identify the key ingredients of strain‐localization and damage hysteresis within plate tectonics and how to represent those in planetary‐scale modeling.
    Beschreibung: Key Points: Comparative analysis of strain localization and damage memory for grain‐size dependent and strain/damage parameterized rheologies. Identification of key ingredients of strain localization and damage hysteresis and how to represent those in planetary‐scale modeling. Plastic strain softening enables hysteresis with a memory duration similar to grain growth at lithospheric temperature conditions.
    Schlagwort(e): 551 ; damage memory ; grain‐size evolution ; strain‐dependent weakening ; strain localization
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  • 79
    Publikationsdatum: 2021-07-04
    Beschreibung: This paper investigates different methods for quantifying thaw subsidence using terrestrial laser scanning (TLS) point clouds. Thaw subsidence is a slow (millimetre to centimetre per year) vertical displacement of the ground surface common in ice‐rich permafrost‐underlain landscapes. It is difficult to quantify thaw subsidence in tundra areas as they often lack stable reference frames. Also, there is no solid ground surface to serve as a basis for elevation measurements, due to a continuous moss–lichen cover. We investigate how an expert‐driven method improves the accuracy of benchmark measurements at discrete locations within two sites using multitemporal TLS data of a 1‐year period. Our method aggregates multiple experts’ determination of the ground surface in 3D point clouds, collected in a web‐based tool. We then compare this to the performance of a fully automated ground surface determination method. Lastly, we quantify ground surface displacement by directly computing multitemporal point cloud distances, thereby extending thaw subsidence observation to an area‐based assessment. Using the expert‐driven quantification as reference, we validate the other methods, including in‐situ benchmark measurements from a conventional field survey. This study demonstrates that quantifying the ground surface using 3D point clouds is more accurate than the field survey method. The expert‐driven method achieves an accuracy of 0.1 ± 0.1 cm. Compared to this, in‐situ benchmark measurements by single surveyors yield an accuracy of 0.4 ± 1.5 cm. This difference between the two methods is important, considering an observed displacement of 1.4 cm at the sites. Thaw subsidence quantification with the fully automatic benchmark‐based method achieves an accuracy of 0.2 ± 0.5 cm and direct point cloud distance computation an accuracy of 0.2 ± 0.9 cm. The range in accuracy is largely influenced by properties of vegetation structure at locations within the sites. The developed methods enable a link of automated quantification and expert judgement for transparent long‐term monitoring of permafrost subsidence. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: This paper investigates methods using terrestrial laser scanning point clouds for quantifying thaw subsidence in permafrost‐underlain tundra fully automatically and by including information collected from expert analysts. Results of the developed methods achieve higher accuracies compared to manual in‐situ measurements, which are found to vary from reference measurements in the magnitude of the actual ground surface displacement observed in a 1‐year period. A link of automated quantification and expert judgement can enable transparent long‐term monitoring of thaw subsidence.
    Beschreibung: German Federal Ministry of Economics and Technology (BMWi) and German Aerospace Center (DLR)
    Beschreibung: Heidelberg Graduate School of Mathematical and Computational Methods for the Sciences, University of Heidelberg http://dx.doi.org/10.13039/501100003801
    Beschreibung: Federal Ministry of Economics and Technology (BMWi) and the German Aerospace Centre (DLR), Germany http://dx.doi.org/10.13039/501100002765
    Schlagwort(e): 551 ; change analysis ; 3D geoinformation ; ground surface displacement ; permafrost monitoring ; multitemporal LiDAR
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  • 80
    Publikationsdatum: 2021-07-05
    Beschreibung: The continental expression of global cooling during the Miocene Climate Transition in Central Asia is poorly documented, as the tectonically active setting complicates the correlation of Neogene regional and global climatic developments. This study presents new geochemical data (CaSO4 content, carbonate δ13C and δ18O) from the endorheic alluvial‐lacustrine Aktau succession (Ili Basin, south‐east Kazakhstan) combined with findings from the previously published facies evolution. Time series analysis revealed long‐eccentricity forcing of the paleohydrology throughout the entire succession, split into several facies‐dependent segments. Orbital tuning, constrained by new laser ablation U‐Pb dates and a preexisting magnetostratigraphy, places the succession in a 5.0 Ma long interval in the middle to late Miocene (15.6 to 10.6 Ma). The long‐term water accumulation in the Ili Basin followed the timing of the Miocene Climate Transition, suggesting increased precipitation in the catchment area in response to climate cooling and stronger westerly winds. This was paced by minima of the 2.4 Ma eccentricity cycle, which favored the establishment of a discharge playa (~14.3 Ma) and a perennial lake (12.6 to 11.8 Ma). Furthermore, low obliquity amplitudes (nodes) caused a transient weakening of the westerlies at ~13.7 to 13.5 Ma and at ~12.7 Ma, resulting in negative hydrological budgets and salinization. Flooding of the windward Ili Basin coeval with aridification in the leeward basins suggests that the Tian Shan was a climate boundary already in the middle Miocene. Our results emphasize the impact of climate fluctuations on the westerlies' strength and thus on Central Asian hydrology.
    Beschreibung: Plain Language Summary: The global climate changed from an exceptional warm to a colder state in the middle Miocene epoch, representing a milestone in the evolution of today's climate. This study focuses on the, so far fragmentary, understanding of the Central Asian climate response to this global climate transition by investigating deposits of a former (salt) lake in the Ili Basin, southeast Kazakhstan. Regular sediment alternations represent cycles of low and high water level, overprinted by a long‐term lake expansion. Time series analysis of climate sensitive geochemical and environmental parameters, together with the determination of absolute rock ages, enabled the identification of sedimentary cycles (405 ka and 1.2 Ma long), which are equivalent to climate influencing variations of the Earth's orbit and tilt angle. We conclude that water level maxima are linked to periods of low seasonal climate differences reoccurring every 405 ka. The lake expansion is caused by more precipitation due to strengthened westerly winds, in response to global cooling. Westerly winds were transiently weakened during periods of low variability of the Earth's tilt angle, promoting high evaporation and salinization. Our results emphasize the impact of climate change on the westerlies' strength and thus on Central Asian moisture supply.
    Beschreibung: Key Points: The endorheic Miocene Ili Basin features orbital control of its hydrological budget by long eccentricity and obliquity amplitude modulation. Obliquity amplitude modulation affected the westerlies' strength during the Miocene Climate Transition. The Miocene global cooling led to strengthening of the westerlies reflected by groundwater accumulation and lake expansion in the Ili Basin.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; orbital forcing ; continental climate ; Central Asia ; Miocene cooling ; integrated stratigraphy
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  • 81
    Publikationsdatum: 2021-07-05
    Beschreibung: Large urban areas are typically characterized by a mosaic of different land uses, with contrasting mixes of impermeable and permeable surfaces that alter “green” and “blue” water flux partitioning. Understanding water partitioning in such heterogeneous environments is challenging but crucial for maintaining a sustainable water management during future challenges of increasing urbanization and climate warming. Stable isotopes in water have outstanding potential to trace the partitioning of rainfall along different flow paths and identify surface water sources. While isotope studies are an established method in many experimental catchments, surprisingly few studies have been conducted in urban environments. Here, we performed synoptic sampling of isotopes in precipitation, surface water and groundwater across the complex city landscape of Berlin, Germany, for a large ‐scale overview of the spatio‐temporal dynamics of urban water cycling. By integrating stable isotopes of water with other hydrogeochemical tracers we were able to identify contributions of groundwater, surface runoff during storm events and effluent discharge on streams with variable degrees of urbanization. We could also assess the influence of summer evaporation on the larger Spree and Havel rivers and local wetlands during the exceptionally warm and dry summers of 2018 and 2019. Our results demonstrate that using stable isotopes and hydrogeochemical data in urban areas has great potential to improve our understanding of water partitioning in complex, anthropogenically‐affected landscapes. This can help to address research priorities needed to tackle future challenges in cities, including the deterioration of water quality and increasing water scarcity driven by climate warming, by improving the understanding of time‐variant rainfall‐runoff behaviour of urban streams, incorporating field data into ecohydrological models, and better quantifying urban evapotranspiration and groundwater recharge.
    Beschreibung: Seasonal isotope and hydrogeochemical dynamics of surface‐ and groundwater in a large urban area following the dry summer of 2018, which was characterized by a temperature anomaly and precipitation deficit.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; ecohydrology ; hydrogeochemistry ; isotopes ; tracers ; urban green spaces ; urban hydrology
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  • 82
    Publikationsdatum: 2021-07-03
    Beschreibung: Soil loss caused by erosion has enormous economic and social impacts. Splash effects of rainfall are an important driver of erosion processes; however, effects of vegetation on splash erosion are still not fully understood. Splash erosion processes under vegetation are investigated by means of throughfall kinetic energy (TKE). Previous studies on TKE utilized a heterogeneous set of plant and canopy parameters to assess vegetation's influence on erosion by rain splash but remained on individual plant‐ or plot‐levels. In the present study we developed a method for the area‐wide estimation of the influence of vegetation on TKE using remote sensing methods. In a literature review we identified key vegetation variables influencing splash erosion and developed a conceptual model to describe the interaction of vegetation and raindrops. Our model considers both amplifying and protecting effect of vegetation layers according to their height above the ground and aggregates them into a new indicator: the Vegetation Splash Factor (VSF). It is based on the proportional contribution of drips per layer, which can be calculated via the vegetation cover profile from airborne LiDAR datasets. In a case study, we calculated the VSF using a LiDAR dataset for La Campana National Park in central Chile. The studied catchment comprises a heterogeneous mosaic of vegetation layer combinations and types and is hence well suited to test the approach. We calculated a VSF map showing the relation between vegetation structure and its expected influence on TKE. Mean VSF was 1.42, indicating amplifying overall effect of vegetation on TKE that was present in 81% of the area. Values below 1 indicating a protective effect were calculated for 19% of the area. For future work, we recommend refining the weighting factor by calibration to local conditions using field‐reference data and comparing the VSF with TKE field measurements. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: The Vegetation Splash Factor maps the amplification or reduction of rain‐fall kinetic energy based on the three‐dimensional vegetation structure. The presented approach allows the area‐wide application based on aerial lidar point clouds and can improve the representation of vegetation in erosion models. This study features a literature review and a case study documenting the development of the new approach.
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; splash erosion ; throughfall kinetic energy ; remote sensing ; LiDAR ; Vegetation Splash Factor
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  • 83
    Publikationsdatum: 2021-07-20
    Beschreibung: We present an Arctic ocean–sea ice reanalysis covering the period 2007–2016 based on the adjoint approach of the Estimating the Circulation and Climate of the Ocean (ECCO) consortium. The spatiotemporal variation of Arctic sea surface temperature (SST), sea ice concentration (SIC), and sea ice thickness (SIT) is substantially improved after the assimilation of ocean and sea ice observations. By assimilating additional World Ocean Atlas 2018 (WOA18) hydrographic data, the freshwater content of the Canadian Basin becomes closer to the observations and translates into changes of the ocean circulation and of transports through the Fram and Davis straits. This new reanalysis compares well with previous filter‐based (TOPAZ4) and nudging‐based (PIOMAS) reanalyses regarding SIC and SST. Benefiting from using the adjoint of the sea ice model, our reanalysis is superior to the ECCOv4r4 product considering sea ice parameters. However, the mean state and variability of the freshwater content and the transport properties of our reanalysis remain different from TOPAZ4 and ECCOv4r4, likely because of a lack of hydrographic observations.
    Beschreibung: Arctic sea ice has declined rapidly and reached a record minimum in September, 2012. Arctic ocean–sea ice reanalyses are invaluable sources for understanding the Arctic sea ice changes. We produce an Arctic ocean–sea ice reanalysis of the years 2007–2016 using the adjoint method. The reanalysis is dynamically consistent without introducing unphysical mass and energy discontinuities as in filter‐based data assimilation methods.
    Schlagwort(e): 551 ; adjoint method ; data assimilation ; ocean–sea ice reanalysis
    Materialart: article
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  • 84
    Publikationsdatum: 2021-07-04
    Beschreibung: Narrow baroclinic fronts are observed in the surface mixed layer (SML) of the Baltic Sea following an autumn storm. The fronts are subjected to hydrodynamic instabilities that lead to submesoscale and turbulent motions while restratifying the SML. We describe observations from an ocean glider that combines currents, stratification, and turbulence microstructure in a high horizontal resolution (150–300 m) to analyze such fronts. The observations show that SML turbulence is strongly modulated by frontal activity, acting as both source and sink for turbulent kinetic energy. In particular, a direct route to turbulent dissipation within the front is linked to shear instability caused by elevated nongeostrophic shear. The turbulent dissipation of frontal kinetic energy is large enough that it could be a significant influence in the evolution of the front and demonstrates that small‐scale turbulence can act as a significant sink of submesoscale kinetic energy.
    Beschreibung: Key Points: An autonomous ocean glider observed turbulence, currents, and stratification in surface mixed layer submesoscale fronts following a storm. Submesoscale fronts provide both a damping and generation of surface mixed layer turbulence. Shear instability within the front could represent a significant energy transfer in frontal evolution.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: Helmholtz Association http://dx.doi.org/10.13039/501100001656
    Schlagwort(e): 551 ; ocean turbulence ; submesoscales ; physical oceanography ; ocean mixing
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  • 85
    Publikationsdatum: 2021-07-04
    Beschreibung: This study presents a meta‐analysis of radiocarbon ages for the environs of Göbekli Tepe – one of the oldest monumental structures worldwide – using cumulative probability functions to diachronically assess phases of geomorphodynamic activity as controlled by natural or anthropogenic drivers. We employ sediment cascades as a heuristic framework to study the complex responses of the geomorphological system to various triggers at local to supra‐regional scales. Possible triggers include climatic variability as documented by supra‐regional hydroclimatic proxy data, regional demographic trends, and local to regional socioeconomic developments such as the emergence of sedentism or the introduction and dispersal of livestock herding. Our results show that phases of intensified geomorphodynamic activity occurred between ca. 7.4–7.0 and 5.8–3.3 ka BP. These phases roughly coincide with phases of population growth in southern Turkey and climatic variations in Turkey and the Levant. The phase between ca. 5.8–3.3 ka BP also corresponds to the time when organized agriculture and the seeder plough were introduced. Also, the identified phases are in agreement with the general trend of varying geomorphodynamic activity in the Eastern Mediterranean as driven by human impact and climatic change. However, neither the Younger Dryas–Holocene transition nor the development of herding during the Pre‐Pottery Neolithic left a clear signature. We demonstrate how the different depositional environments in the studied landscape compartments vary with respect to their spatiotemporal coverage and discuss challenges when trying to understand processes that once shaped landscapes of past societies. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
    Beschreibung: Geomorphodynamic activity in the surroundings of the Early Neolithic hilltop site Göbekli Tepe is significantly intensified between ca. 7.4–7.0 and 5.8–3.3 ka BP, reflecting demographic, sociocultural, and climatic variations. The studied landscape compartments form a sediment cascade whose different depositional environments vary with respect to their spatiotemporal coverage. Preservation of colluvial deposits in upland catchments represents a key challenge when studying ancient hilltop sites such as Göbekli Tepe in semi‐arid environments like southeastern Anatolia.
    Schlagwort(e): 551 ; Holocene geomorphodynamic activity ; cumulative probability functions of 14C ages ; human–environment interactions ; geoarchaeology ; sediment connectivity
    Materialart: article
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  • 86
    Publikationsdatum: 2021-07-04
    Beschreibung: Large rock slope failures play a pivotal role in long‐term landscape evolution and are a major concern in land use planning and hazard aspects. While the failure phase and the time immediately prior to failure are increasingly well studied, the nature of the preparation phase remains enigmatic. This knowledge gap is due, to a large degree, to difficulties associated with instrumenting high mountain terrain and the local nature of classic monitoring methods, which does not allow integral observation of large rock volumes. Here, we analyse data from a small network of up to seven seismic sensors installed during July–October 2018 (with 43 days of data loss) at the summit of the Hochvogel, a 2592 m high Alpine peak. We develop proxy time series indicative of cyclic and progressive changes of the summit. Modal analysis, horizontal‐to‐vertical spectral ratio data and end‐member modelling analysis reveal diurnal cycles of increasing and decreasing coupling stiffness of a 260,000 m3 large, instable rock volume, due to thermal forcing. Relative seismic wave velocity changes also indicate diurnal accumulation and release of stress within the rock mass. At longer time scales, there is a systematic superimposed pattern of stress increased over multiple days and episodic stress release within a few days, expressed in an increased emission of short seismic pulses indicative of rock cracking. Our data provide essential first order information on the development of large‐scale slope instabilities towards catastrophic failure. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.
    Beschreibung: We use a small seismic networks on the summit of the Hochvogel to record continuous and discrete failure preparation signals of a large‐scale slope instability. Reversible and irreversible mechanisms at the diurnal, multi‐day and seasonal scale are quantified. We infer an early stage of stick slip motion and thermally forced diurnal stress release and rock mass stiffness changes.
    Schlagwort(e): 551 ; environmental seismology ; fatigue ; fundamental frequency ; HVSR ; mass wasting ; mountain geomorphology ; natural hazard ; noise cross correlation ; seismic monitoring ; slope failure
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  • 87
    Publikationsdatum: 2021-06-30
    Beschreibung: Chronological uncertainty complicates attempts to use radiocarbon dates as proxies for processes such as human population growth/decline, forest fires and marine ingression. Established approaches involve turning databases of radiocarbon‐date densities into single summary proxies that cannot fully account for chronological uncertainty. Here, I use simulated data to explore an alternative Bayesian approach that instead models the data as what they are, namely radiocarbon‐dated event counts. The approach involves assessing possible event‐count sequences by sampling radiocarbon date densities and then applying a Markov Chain Monte Carlo method to estimate the parameters of an appropriate count‐based regression model. The regressions based on individual sampled sequences were placed in a multilevel framework, which allowed for the estimation of hyperparameters that account for chronological uncertainty in individual event times. Two processes were used to produce simulated data. One represented a simple monotonic change in event‐counts and the other was based on a real palaeoclimate proxy record. In both cases, the method produced estimates that had the correct sign and were consistently biased towards zero. These results indicate that the approach is widely applicable and could form the basis of a new class of quantitative models for use in exploring long‐term human and environmental processes.
    Schlagwort(e): 551 ; archaeology ; Bayesian regression ; palaeoclimatology ; radiocarbon dating ; radiocarbon‐dated event count (REC) model
    Materialart: article
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  • 88
    Publikationsdatum: 2021-07-21
    Beschreibung: Evaporation experiments are frequently used to determine soil hydraulic properties. We simulated laboratory evaporation experiments with a coupled water, vapor, and heat flow model which includes the surface energy balance. The simulations are performed with different parametrizations of soil hydraulic properties with a focus on soil hydraulic conductivity in medium to dry soil. In previous studies, conductivity in this moisture range has been shown to be influenced not only by water flow in completely filled capillaries (“capillary flow”) but also by film and corner flow (“film flow”). Our forward simulations highlight the strong influence of an increased conductivity caused by film flow on evaporation rate, cumulative water loss, soil temperature, and soil water pressure head during evaporation. Film flow extends the duration of stage‐1 evaporation and increases the evaporation rate during stage‐2 even if all other physical material properties are the same. The simulated data were used in inverse simulations with the Richards equation to test whether soil hydraulic properties can be identified without bias. This is a priori questionable because the Richards equation is an isothermal flow model and simplifies the true physics considerably, by ignoring thermal liquid and thermal vapor fluxes, as well as temperature effects on the hydraulic properties. Our results show that the identification of the water retention and hydraulic conductivity curves is bias‐free for media with and without film flow. We conclude that the Richards equation can be safely used to identify hydraulic properties from evaporation experiments by inverse modeling.
    Beschreibung: Key Points: Coupled modeling of water, vapor, and heat flow shows that film‐flow extends stage‐1 and changes the evaporation dynamics during stage‐2. Soil hydraulic properties identified by inverse modeling with the Richards equation are unbiased despite strong temperature dynamics. Inadequate models for soil hydraulic properties lead to a grossly wrong prediction of the pressure head in medium to dry soils.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; evaporation ; hydraulic conductivity ; film flow ; soil hydraulic properties ; vapor flow ; water retention curve
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  • 89
    Publikationsdatum: 2021-07-21
    Beschreibung: The Laacher See volcano (LSV) is located at the western margin of the Neuwied Basin, the central part of the Middle Rhine Basin of Germany. Its paroxysmal Plinian eruption c. 13 ka ago (Laacher See event; LSE) deposited a complex tephra sequence in the Neuwied Basin, whilst the distal ashes became one of the most important chronostratigraphic markers in Central Europe. However, some other impacts on landscape formation have thus far been largely neglected, such as buried gully structures in the proximity of the LSV. In this contribution, we map and discuss the spatial extent of these landforms at the site Lungenkärchen c. 4 km south of the LSV based on geophysical prospection as well as contrasting pedo‐sedimentary characteristics of the gully infill (particle‐size distribution, bulk‐sediment density, thin‐section analysis, saturated hydraulic conductivity) and the surrounding soils and tephra layers. These data are combined with a luminescence‐ and carbon‐14 (14C)‐based age model that relates them to the LSE. It is demonstrated how these gullies seem to have been formed and rapidly infilled by rainfall and surface discharge both during and subsequent to the eruptive phase, with modern analog processes documented for the 1980 Mount St Helens eruption (Washington State, USA). Given the density of the gullies at the site and their deviating pedo‐sedimentary properties compared to the surrounding soils, we propose a significant influence on agricultural production in the proximity of the LSV, which remains to be tested in future studies. Finally, in contrast, gullies of similar lateral and vertical dimensions identified in post‐LSE reworked loess and tephra deposits of the Wingertsbergwand (close to the main study site and proximal to the LSV) have shown to be unrelated to the LSE and can either be attributed to periglacial processes at the Younger Dryas‐Preboreal transition or to linear incision during the early Holocene.
    Beschreibung: Linear subsurface gullies were identified close to the Laacher See volcano in magnetometer and ground‐penetrating radar prospection. Optically stimulated luminescence data indicate they incised during or shortly after the Laacher See event 13 ka ago. Pedo‐sedimentary characteristics of the gully infill differs from the surrounding regosols and brown earths, possibly influencing regional agricultural land use. image
    Beschreibung: University of Cologne http://dx.doi.org/10.13039/501100008001
    Beschreibung: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; 554.3 ; Eifel ; ground‐penetrating radar (GPR) ; gully erosion ; Laacher See event (LSE) ; luminescence dating ; magnetometer prospection ; micromorphology ; tephra ; Wingertsbergwand
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  • 90
    Publikationsdatum: 2021-07-21
    Beschreibung: To evaluate the present sea ice changes in a longer‐term perspective, the knowledge of sea ice variability on preindustrial and geological time scales is essential. For the interpretation of proxy reconstructions it is necessary to understand the recent signals of different sea ice proxies from various regions. We present 260 new sediment surface samples collected in the (sub‐)Arctic Oceans that were analyzed for specific sea ice (IP25) and open‐water phytoplankton biomarkers (brassicasterol, dinosterol, and highly branched isoprenoid [HBI] III). This new biomarker data set was combined with 615 previously published biomarker surface samples into a pan‐Arctic database. The resulting pan‐Arctic biomarker and sea ice index (PIP25) database shows a spatial distribution correlating well with the diverse modern sea ice concentrations. We find correlations of PBIP25, PDIP25, and PIIIIP25 with spring and autumn sea ice concentrations. Similar correlations with modern sea ice concentrations are observed in Baffin Bay. However, the correlations of the PIP25 indices with modern sea ice concentrations differ in Fram Strait from those of the (sub‐)Arctic data set, which is likely caused by region‐specific differences in sea ice variability, nutrient availability, and other environmental conditions. The extended (sea ice) biomarker database strengthens the validity of biomarker sea ice reconstructions in different Arctic regions and shows how different sea ice proxies combined may resolve specific seasonal sea ice conditions.
    Beschreibung: Key Points: IP25 provides information about modern sea ice cover on a (sub‐)Arctic‐wide scale. All PIP25 indices correlate well with spring and autumn sea ice concentrations on a (sub‐)Arctic‐wide scale. The combination of biomarker data and dinoflagellate cysts may yield an approach to reconstruct sea ice conditions during different seasons.
    Beschreibung: EC | Seventh Framework Programme (FP7) http://dx.doi.org/10.13039/100011102
    Beschreibung: European Research Council http://dx.doi.org/10.13039/501100000781
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; biomarker ; IP25 ; PIP25 ; sea ice ; Baffin Bay ; Fram Strait
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  • 91
    Publikationsdatum: 2021-07-21
    Beschreibung: The warming of rock permafrost affects mechanical stability and hydro‐cryostatic pressures in rock walls. The coincident decrease in slope stability frequently affects infrastructure by creep and subsidence and promotes the generation of rockfalls and rockslides. The increasing hazard posed by warming permafrost rock walls and the growing exposure of infrastructure and individuals create a demand for quantitative monitoring methods. Laboratory‐calibrated electrical resistivity tomography provides a sensitive record for frozen versus unfrozen bedrock, presumably being the most accurate quantitative monitoring technique in permafrost areas where boreholes are not available. The data presented here are obtained at the permafrost‐affected and unstable Steintaelli Ridge at 3100 m a.s.l. and allow the quantification of permafrost changes in the longest electrical resistivity tomography time series in steep bedrock. Five parallel transects across the rock ridge have been measured five times each, between 2006 and 2019, with similar hardware. Field measurements were calibrated using temperature‐resistivity laboratory measurements of water‐saturated rock samples from the site. A 3D time‐lapse inversion scheme is applied in the boundless electrical resistivity tomography (BERT) software for the inversion of the data. To assess the initial data quality, we compare the effect of data filtering and the robustness of final results with three different filters and two time‐lapse models. We quantify the volumetric permafrost distribution in the bedrock and its degradation in the last decades. Our data show mean monthly air temperatures to increase from −3.4°C to −2.6°C between 2005‒2009 and 2015‒2019, respectively, while simultaneously permafrost volume degraded on average from 6790 m3 (±640 m3 rock in phase‐transition range) in 2006 to 3880 m3 (±1000 m3) in 2019. For the first time, we provide a quantitative measure of permafrost degradation in unstable bedrock by using a temperature‐calibrated 4D electrical resistivity tomography. Our approach represents a fundamental benchmark for the evaluation of climate change effects on bedrock permafrost.
    Schlagwort(e): 622.15 ; 551 ; Climate change ; ERT ; Geohazard ; 3D
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  • 92
    Publikationsdatum: 2021-07-21
    Beschreibung: The sediment succession of Lake Emanda in the Yana Highlands was investigated to reconstruct the regional late Quaternary climate and environmental history. Hydro‐acoustic data obtained during a field campaign in 2017 show laminated sediments in the north‐western and deepest (up to ̃15 m) part of the lake, where a ̃6‐m‐long sediment core (Co1412) was retrieved. The sediment core was studied with a multi‐proxy approach including sedimentological and geochemical analyses. The chronology of Co1412 is based on 14C AMS dating on plant fragments from the upper 4.65 m and by extrapolation suggests a basal age of c. 57 cal. ka BP. Pronounced changes in the proxy data indicate that early Marine Isotope Stage (MIS) 3 was characterized by unstable environmental conditions associated with short‐term temperature and/or precipitation variations. This interval was followed by progressively colder and likely drier conditions during mid‐MIS 3. A lake‐level decline between 32.0 and 19.1 cal. ka BP was presumably related to increased continentality and dry conditions peaking during the Last Glacial Maximum (LGM). A subsequent rise in lake level could accordingly have been the result of increased rainfall, probably in combination with seasonally high meltwater input. A milder or wetter Lateglacial climate increased lake productivity and vegetation growth, the latter stabilizing the catchment and reducing clastic input into the lake. The Bølling‐Allerød warming, Younger Dryas cooling and Holocene Thermal Maximum (HTM) are indicated by distinct changes in the environment around Lake Emanda. Unstable, but similar‐to‐present‐day climatic and environmental conditions have persisted since c. 5 cal. ka BP. The results emphasize the highly continental setting of the study site and therefore suggest that the climate at Lake Emanda was predominantly controlled by changes in summer insolation, global sea level, and the extent of ice sheets over Eurasia, which influenced atmospheric circulation patterns.
    Beschreibung: Bundesministerium für Bildung und Forschung
    Schlagwort(e): 551 ; Siberia ; Lake Emanda ; late Quaternary ; climate history ; environmental history
    Materialart: article
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  • 93
    Publikationsdatum: 2021-07-21
    Beschreibung: Stable isotopes (δ18O, δD) of wedge ice hold potential to reconstruct past winter climate conditions. Here, we present records of the marine isotope stages (MIS) 3 and 2 including the last Glacial maximum (LGM) from Bol’shoy Lyakhovsky Island (NE Siberia). MIS 3 wedge ice dated from 52 to 40 Kyr b2k varies between −32 and −29‰ in δ18O. Colder LGM conditions are implied by δ18O of −37‰ around 25 Kyr b2k. Similar Deuterium excess values indicate comparable moisture sources during MIS 3 and MIS 2. Regional LGM climate reconstructions depend on the seasonal resolution of the proxies and model simulations. Our wedge‐ice record reflects coldest winters during global minima in atmospheric CO2 and sea level. The extreme LGM winter cooling is not represented in model projections of global LGM climate where West Beringia shows noticeably little cooling or even warming in mean annual temperatures compared to the late Holocene.
    Beschreibung: Plain Language Summary: The geochemical signature of stable isotopes of permafrost ground ice preserves information about past climate conditions. A common type of ground ice is ice wedges that form by the freezing of snowmelt in frost cracks developed on the ground and grow over time in width and length. Winter temperatures, and the type (snow or rain) and origin (regional moisture source) of winter precipitation largely control the stable isotope characteristics of oxygen and hydrogen in ice wedges. Here, we study the stable isotope composition of ice wedges from the last glacial period in northeastern Siberia. Plant and animal fossils that were found within the ice and in the surrounding frozen ground provide age control spanning from more than 50 to 24 thousand years ago when the ice wedges grew. The coldest winter conditions are inferred from a New Siberian Island ice‐wedge site as indicated by the lowest stable isotope values of all our sampled ice wedges at times, corresponding to the last Glacial maximum around 25 thousand years ago.
    Beschreibung: Key Points: Pronounced west Beringian MIS 3 to MIS 2 winter cooling delineated in wedge‐ice stable isotope signatures. Coldest winters reflected by exceptionally depleted values of −37.4 ± 0.4‰ in δ18O and −292 ± 3‰ in δD in LGM wedge ice. LGM wedge ice directly radiocarbon‐dated to 25,890 and 23,980 yr b2k.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Beschreibung: German Federal Ministry of Education and Research
    Schlagwort(e): 551 ; ground ice ; last Glacial maximum ; permafrost ; radiocarbon ; Siberia ; stable isotopes
    Materialart: article
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  • 94
    Publikationsdatum: 2021-06-16
    Beschreibung: Information on water balance components such as evapotranspiration and groundwater recharge are crucial for water management. Due to differences in physical conditions, but also due to limited budgets, there is not one universal best practice, but a wide range of different methods with specific advantages and disadvantages. In this study, we propose an approach to quantify actual evapotranspiration, groundwater recharge and water inflow, i.e. precipitation and irrigation, that considers the specific conditions of irrigated agriculture in warm, arid environments. This approach does not require direct measurements of precipitation or irrigation quantities and is therefore suitable for sites with an uncertain data basis. For this purpose, we combine soil moisture and energy balance monitoring, remote sensing data analysis and numerical modelling using Hydrus. Energy balance data and routine weather data serve to estimate ET0. Surface reflectance data from satellite images (Sentinel‐2) are used to derive leaf area indices, which help to partition ET0 into energy limited evaporation and transpiration. Subsequently, first approximations of water inflow are derived based on observed soil moisture changes. These inflow estimates are used in a series of forward simulations that produce initial estimates of drainage and ETact, which in turn help improve the estimate of water inflow. Finally, the improved inflow estimates are incorporated into the model and then a parameter optimization is performed using the observed soil moisture as the reference figure. Forward simulations with calibrated soil parameters result in final estimates for ETact and groundwater recharge. The presented method is applied to an agricultural test site with a crop rotation of cotton and wheat in Punjab, Pakistan. The final model results, with an RMSE of 2.2% in volumetric water content, suggest a cumulative ETact and groundwater recharge of 769 and 297 mm over a period of 281 days, respectively. The total estimated water inflow accounts for 946 mm, of which 77% originates from irrigation.
    Beschreibung: Approach to quantify ETact, GWR and water inflow that considers the specific conditions of irrigated agriculture in warm, acid environments. It combines soil moisture and energy balance monitoring, remote sensing data analysing data analysis and numerical modelling using Hydrus. The final model results suggest that GWR accounts for one third of the total water inflow, of which 77% originates from irrigations. image
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): 551 ; actual evapotranspiration ; ground heat flux ; groundwater recharge ; Hydrus ; irrigation ; net radiation ; Sentinel‐2 ; soil moisture
    Materialart: article
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  • 95
    Publikationsdatum: 2021-07-21
    Beschreibung: Bare‐soil evaporation involves coupled flow of liquid water, water vapor, and heat. As evaporation results in non‐isothermal conditions in the soil, the temperature dependence of transport properties and thermal fluxes of water and vapor must be accounted for. In a companion paper, we showed that the Richards equation, that is, a single‐phase flow model assuming isothermal conditions, is applicable to accurately determine soil hydraulic properties including the medium to dry range from evaporation experiments by inverse modeling. This is warranted if pressure head data across a wide moisture range, that is, from almost saturated to almost air‐dry, are used in the objective function and a suitable parameterization of the hydraulic conductivity function including vapor and non‐capillary flow is used. In this article, we confirm the theoretical results by examining real evaporation experiments, in which we measured the temporal dynamics of evaporation rate, soil temperature, and pressure head in laboratory soil columns. Pressure head was measured with mini‐tensiometers and relative humidity sensors. The measurements were evaluated by inverse modeling with the Richards equation assuming isothermal conditions and ambient temperature in the soil. Our results for a sandy and a loamy soil show that the observed transient water and vapor dynamics in the drying soil could be accurately matched, provided the hydraulic conductivity curve considered isothermal vapor diffusion and film flow. These components dominate hydraulic conductivity in the medium to dry soil moisture range and were uniquely identified in agreement with the theoretical analysis in the companion article.
    Beschreibung: Key Points: Identification of soil hydraulic properties across the full moisture range by inverse modeling of evaporation experiments. Advanced instrumentation with tensiometers and relative humidity sensors allows to identify hydraulic conductivity in medium to dry soil. Evaporation experiments can be modeled correctly with Richards’ equation, provided hydraulic properties account for vapor and film flow.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; Evaporation ; hydraulic conductivity ; inverse modeling ; soil hydraulic properties ; vadose zone ; water retention curve
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  • 96
    Publikationsdatum: 2021-07-21
    Beschreibung: The separation between Australia and Antarctica occurred during the final stages of the break‐up of Pangea. Reconstructions of the rifting of the Australian plate away from Antarctica show fast spreading rates since Mid‐Eocene (45 Ma). These reconstructions can be used to understand and quantify the forces driving the Australia/Antarctica separation, and to test hypotheses on mechanisms that may be of shallow (i.e., lithosphere) or deep (i.e., mantle) origin. Analytical calculations indicate that plate‐boundary forces are highly unlikely to be a plausible candidate to explain such a separation. Thus, we use a recently developed global coupled models of mantle and lithosphere dynamics, here we show that this event, whose kinematics are reproduced in our models within the bounds of the reconstruction uncertainties, owes to a significant degree to the pressure‐driven asthenospheric Poiseuille flow associated with the mantle buoyancy field inherited from viscous circulation history throughout the Mesozoic. On the contrary, in simulations when such a buoyancy field is replaced by another one resulting from a random distribution of mantle temperature–thus not representative of Earth’s mantle circulation history–the rapid northward motion of Australia does not occur. Similarly, suppressing contemporaneous plate‐boundary processes (i.e., subduction of the Pacific ridge at the Aleutians and healing of the India‐Australia ridge) from our models does not have a noticeable effect on the Australia‐Antarctica kinematics. Thus, a pressure‐driven Poiseuille mantle flow must be considered, at least in this example and possible elsewhere, as a main driver of plate tectonics.
    Beschreibung: Key Points: Reconstructions of the rifting of the Australian plate away from Antarctica shows fast spreading rates since Mid‐Eocene (45 Ma). Analyzed mechanisms to separate the Australian plate from Antarctica using coupled global models of mantle and lithosphere dynamics. Results indicate that the separation between the Australian and Antarctica plate was driven by an asthenospheric pressure Poiseuille flow.
    Beschreibung: Københavns Universitet http://dx.doi.org/10.13039/501100001734
    Schlagwort(e): 551 ; mantle circulation history ; pressure‐driven Poiseuille flow ; separation of Australia/Antarctica
    Materialart: article
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  • 97
    Publikationsdatum: 2021-07-21
    Beschreibung: Lahars are among the most hazardous mass flow processes on earth and have caused up to 23 000 casualties in single events in the recent past. The Cotopaxi volcano, 60 km southeast of Quito, has a well‐documented history of massively destructive lahars and is a hotspot for future lahars due to (i) its ~10 km2 glacier cap, (ii) its 117–147‐year return period of (Sub)‐Plinian eruptions, and (iii) the densely populated potential inundation zones (300 000 inhabitants). Previous mechanical lahar models often do not (i) capture the steep initial lahar trajectory, (ii) reproduce multiple flow paths including bifurcation and confluence, and (iii) generate appropriate key parameters like flow speed and pressure at the base as a measure of erosion capacity. Here, we back‐calculate the well‐documented 1877 lahar using the RAMMS debris flow model with an implemented entrainment algorithm, covering the entire lahar path from the volcano edifice to an extent of ~70 km from the source. To evaluate the sensitivity and to constrain the model input range, we systematically explore input parameter values, especially the Voellmy–Salm friction coefficients μ and ξ. Objective selection of the most likely parameter combinations enables a realistic and robust lahar hazard representation. Detailed historic records for flow height, flow velocity, peak discharge, travel time and inundation limits match best with a very low Coulomb‐type friction μ (0.0025–0.005) and a high turbulent friction ξ (1000–1400 m/s2). Finally, we apply the calibrated model to future eruption scenarios (Volcanic Explosivity Index = 2–3, 3–4, 〉4) at Cotopaxi and accordingly scaled lahars. For the first time, we anticipate a potential volume growth of 50–400% due to lahar erosivity on steep volcano flanks. Here we develop a generic Voellmy–Salm approach across different scales of high‐magnitude lahars and show how it can be used to anticipate future syneruptive lahars.
    Beschreibung: A generic model approach is developed to simulate massive syneruptive lahars at Cotopaxi from initiation on the steep volcano flanks to distal reaches. Evaluation of 14 calibration constraints shows that the Voellmy–Salm model reliably reproduces bulk behaviour of syneruptive lahars. Estimations of lahar erosivity on the volcano flanks anticipate an erosion‐related volume increase for future Cotopaxi lahars between 50 and 400%.
    Beschreibung: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Schlagwort(e): 551 ; debris flow erosion ; lahar ; model calibration ; numerical model ; predictive modelling
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Publikationsdatum: 2021-04-22
    Beschreibung: The seasonal cycle represents one of the largest signals of dissolved inorganic carbon (DIC) in the ocean, yet these seasonal variations are not well established at a global scale. Here, we present the Mapped Observation‐Based Oceanic DIC (MOBO‐DIC) product, a monthly DIC climatology developed based on the DIC measurements from GLODAPv2.2019 and a two‐step neural network method to interpolate and map the measurements. MOBO‐DIC extends from the surface down to 2,000 m and from 65°N to 65°S. We find the largest seasonal amplitudes of surface DIC in the northern high‐latitude Pacific (∼30 to 〉50 μmol kg−1). Surface DIC maxima occur in hemispheric spring and minima in fall, driven by the input of DIC into the upper ocean by mixing during winter, and net community production (NCP) driven drawdown of DIC over summer. The seasonal pattern seen at the surface extends to a nodal depth of 〈50 m in the tropics and several hundred meters in the subtropics. Below the nodal depth, the seasonal cycle of DIC has the opposite phase, primarily owing to the seasonal accumulation of DIC stemming from the remineralization of sinking organic matter. The well‐captured seasonal drawdown of DIC in the mid‐latitudes (23° to 65°) allows us to estimate the spring‐to‐fall NCP in this region. We find a spatially relatively uniform spring‐to‐fall NCP of 1.9 ± 1.3 mol C m−2 yr−1, which sums to 3.9 ± 2.7 Pg C yr−1 over this region. This corresponds to a global spring‐to‐fall NCP of 8.2 ± 5.6 Pg C yr−1.
    Beschreibung: Key Points We present a near‐global monthly DIC climatology (MOBO‐DIC) based on ship observations and a two‐step neural network Seasonal surface DIC amplitudes range from 0 to more than 50 μmol kg−1 MOBO‐DIC yields a spring‐to‐fall NCP in the euphotic zone of the mid‐latitudes of 3.9 ± 2.7 Pg C yr−1
    Beschreibung: European Community's Horizon 2020 Project
    Beschreibung: International Max Planck Research School on Earth System Modelling (IMPRS‐ESM)
    Schlagwort(e): 551 ; DIC ; seasonal variability ; neural networks ; SOM‐FFN ; monthly climatology ; NCP
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Publikationsdatum: 2021-07-04
    Beschreibung: Variations in depositional rates affect the temporal depositional resolutions of proxies used for paleoenvironmental reconstructions; for example, condensation can make reconstructed environmental changes appear very abrupt. This is commonly addressed by transforming proxy data using age models, but this approach is limited to situations where numerical ages are available or can be reliably inferred by correlation. Here we propose a new solution, in which relative age models are constructed based on proxies for depositional rates. As a case study, we use the onset of the late Silurian Lau Carbon Isotope Excursion (LCIE) in Gotland, Sweden. The studied succession is a gradual record of shallowing upward in a tropical, neritic carbonate platform. As proxies for depositional rates we tested thorium concentration, carbonate content, and the concentration of pelagic palynomorphs. These three proxies were used to create relative age models using the previously published DAIME model. We applied these models to transform the δ13Ccarb values as well as concentrations of selected redox‐sensitive elements. The three relative age models yielded qualitatively similar results. In our case study, variations in depositional rates resulted in peaks of redox proxies appearing up to 76% higher when taken at face value, compared to when accounting for these rates. In the most extreme cases, our corrections resulted in a reversal in the stratigraphic trend of elemental concentrations. This approach can be applied and developed across depositional setting and types of paleoenvironmental proxies. It provides a flexible tool for developing quantitative models to improve our understanding of the stratigraphic record.
    Beschreibung: Plain Language Summary: The depositional rate reflects how quickly a given thickness of sedimentary rock forms. Abrupt changes in environmental signals recorded in an interval of strata can be the result of (1) fast changes in environmental conditions and average sedimentation rate or (2) average changes in environmental conditions and slow sedimentation rate. To correct for this effect, age models are used, but they are often not available or lack sufficient resolution to detect rapid changes in the environment. We propose a method to estimate relative changes in depositional rates and test it in a sedimentary section on the Swedish island of Gotland. The section preserves geochemical records of a carbon cycle perturbation, expressed as shifts in carbon isotopes. It has also been proposed to record periods of oxygen depletion in marine water, detectable as enrichment in elements sensitive to redox conditions. We measured these parameters and compared the original values as preserved in the section with values corrected for depositional rates. We show that (1) perturbations of the carbon cycle were most likely more rapid than they appear in the section and (2) high depositional rates during the carbon cycle perturbation partly disguised the intervals of oxygen depletion.
    Beschreibung: Key Points: Relative age models are reconstructed from concentrations of Th, carbonate, and pelagic palynomorphs. δ13Ccarb and elemental proxies for redox conditions are transformed using the age models. Accounting for depositional rates can decrease peaks in redox proxies by up to 45% and make the δ13Ccarb excursion appear more abrupt.
    Beschreibung: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Schlagwort(e): 551 ; depositional rate ; sedimentation rate ; age model ; thorium ; Silurian ; anoxia
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Publikationsdatum: 2021-07-04
    Beschreibung: Insolation differences play a primary role in controlling microclimate and vegetation cover, which together influence the development of topography. Topographic asymmetry (TA), or slope differences between terrain aspects, has been well documented in small‐scale, field‐based, and modeling studies. Here we combine a suite of environmental (e.g., vegetation, temperature, solar insolation) and topographic (e.g., elevation, drainage network) data to explore the driving mechanisms and markers of TA on a global scale. Using a novel empirical TA analysis method, we find that (1) steeper terrain has higher TA magnitudes, (2) globally, pole‐facing terrain is on average steeper than equator‐facing terrain, especially in mid‐latitude, tectonically quiescent, and vegetated landscapes, and (3) high‐elevation and low‐temperature regions tend to have terrain steepened toward the equator. We further show that there are distinct differences in climate and vegetation cover across terrain aspects, and that TA is reflected in the size and form of fluvial drainage networks. Our work supports the argument that insolation asymmetries engender differences in local microclimates and vegetation on opposing terrain aspects, which broadly encourage the development of asymmetric topography across a range of lithologic, tectonic, geomorphic, and climatic settings.
    Beschreibung: Key Points: Steep terrain has higher topographic asymmetry magnitudes. Pole‐facing terrain is on average steeper than equator‐facing terrain. High‐elevation and low‐temperature regions tend to have terrain steepened towards the equator.
    Schlagwort(e): 551 ; erosion ; freeze‐thaw cycling ; solar radiation ; topographic asymmetry ; topography ; vegetation cover
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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