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  • 1
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    Volcano‐Tectonic Evolution of the Christiana‐Santorini‐Kolumbo Rift Zone (2022)
    Details
    Publication Date: 2023-09-12
    Description: Located on the Hellenic Arc, the Christiana‐Santorini‐Kolumbo (CSK) rift zone represents one of the most active and hazardous volcano‐tectonic systems in the Mediterranean. Although this rift zone has been intensively studied, its tectonic evolution and the interplay of volcanism and tectonism are still poorly understood. In this study, we use high‐resolution reflection seismic imagery to reconstruct the opening of the rift basins. For the first time, we relate the activity of individual faults with the activity of specific volcanic centers in space and time. Our analysis shows a pre‐volcanic NNE‐SSW‐oriented paleo basin underneath the CSK volcanoes, representing a transfer zone between Pliocene ESE‐WNW‐oriented basins, which was overprinted by a NE‐SW‐oriented tectonic regime hosting Late Pliocene volcanism that initiated at the Christiana Volcano. All subsequent volcanoes evolved parallel to this trend. Two major Pleistocene tectonic pulses preceded fundamental changes in the volcanism of the CSK rift including the occurrence of widespread small‐scale volcanic centers followed by focusing of activity at Santorini with increasing explosivity. The observed correlation between changes in the tectonic system and the magmatism of the CSK volcanoes suggests a deep‐seated tectonic control of the volcanic plumbing system. In turn, our analysis reveals the absence of large‐scale faults in basin segments affected by volcanism indicating a secondary feedback mechanism on the tectonic system. A comparison with the evolution of the neighboring Kos‐Nisyros‐Yali volcanic field zone and Rhodos highlights concurrent regional volcano‐tectonic changes, suggesting a potential arc‐wide scale of the observed volcano‐tectonic interplay.
    Description: Plain Language Summary: How do regional tectonic movements and large volcanoes interact? Seismological studies indicate complex volcano‐tectonic feedback links, but, so far, information on the long‐term interactions between tectonics and volcanism is rarely available. The Christiana‐Santorini‐Kolumbo (CSK) rift zone lies in the Aegean Sea and is notorious for its devastating volcanic eruptions, earthquakes, and tsunamis. This region offers the opportunity to study volcano‐tectonic interactions over several million years. In this study, we use high‐resolution seismic imagery to reconstruct the evolution of the rift basins and the CSK volcanoes. We find that all volcanoes lie in a Pliocene transfer zone connecting extensional basins. Volcanism initiated as this older tectonic regime was intersected by a NE‐SW‐directed fault system. Subsequently, all volcanoes evolved parallel to this trend. Several distinct tectonic reorganizations occurred in the Pleistocene, which had a pronounced influence on the CSK volcanoes. In turn, our analysis indicates that the emergence of volcanism also impacted the tectonic evolution of the rift system hindering the evolution of large‐scale normal faults in the volcanic basins. The observed tectonic reorganizations seem to reflect major changes in the stress regime of the Hellenic Arc, potentially also affecting adjacent volcanic centers whose volcano‐tectonic evolution is only poorly constrained so far.
    Description: Key Points: We reconstruct the volcano‐tectonic evolution of the Christiana‐Santorini‐Kolumbo rift zone using multichannel seismic data. The overprint of a Pleistocene NE‐SW striking fault system on a Pliocene E‐W oriented system initiated the emergence of volcanism. Regional tectonics had a primary control on the volcanic plumbing system, while magmatism had a secondary influence on the tectonic system.
    Description: German Research Foundation DFG
    Description: https://doi.org/10.26022/IEDA/331028
    Keywords: ddc:551.8 ; volcano‐tectonics ; Santorini ; rifting ; back‐arc ; Hellenic Arc ; Aegean Sea
    Language: English
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  • 2
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    Bayesian Quantification and Reduction of Uncertainties in 3D Geomechanical‐Numerical Models (2022)
    Details
    Publication Date: 2023-09-13
    Description: The distance to failure of the upper crustal rock in the prevalent stress field is of importance to better understand fault reactivation by natural and induced processes as well as to plan and manage georeservoirs. In particular, the contemporary stress state is one of the key ingredients for this assessment. To provide a continuous description of the 3D absolute stress state geomechanical‐numerical models are used. However, stress magnitude data for model calibration are sparse and incomplete and thus, the resulting model uncertainties are large. In order to reduce the uncertainties, we incorporate additional constraints on stress magnitudes to check the plausibility of different data‐based stress states. We use formation integrity tests, borehole breakouts, drilling induced fractures, and observations of seismicity and distinct seismological quiescence. This information is weighted according to its confidence and the agreement with the different modeled stress states is assessed. The information is introduced to a Bayesian approach to estimate weights of the modeled stress states and thereby identify their plausibility. A case study in southern Germany shows the ability of the approach to identify from a wide range of stress states a small number of plausible ones and reject implausible stress states. This significantly reduces the number of stress states and thus lowers the model uncertainties.
    Description: Plain Language Summary: The upper crust of the Earth (upper few kilometers) is subject to a kind of pressure, referred to as stress. When the stress becomes larger than the strength of the rock, the rock breaks. Sometimes this can be measured or even felt as a seismic event. It happens naturally but may also happen due to human activity. To prevent such induced seismic event, it is important to know the stress state. But there is only few information on the magnitude of the stress so we need computer models to predict the stress state. These models are often not very precise since there is only few information on the stress magnitudes and in addition they are often contradicting. We use all stress magnitude information individually to model various stress states. Then we look at other information that is related to the stress state but does not provide stress magnitude information on its own. We compare this information with the modeled stress states to find out whether a stress state agrees with the additional information or not. This allows us to identify a few realistic stress state models out of a wide range of possible ones. This reduces the uncertainties of the stress predictions.
    Description: Key Points: Bayesian approach to uncertainty quantification and reduction of 3D geomechanical‐numerical models of the undisturbed stress state. Additional constraints on the stress state by formation integrity tests, borehole breakouts, and drilling induced tensile fractures. Constraints on the differential stress by observation of seismicity or distinct seismological quiescence.
    Description: Bundesministerium für Bildung, Wissenschaft und Forschung http://dx.doi.org/10.13039/501100013699
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Description: Helmholtz Centre Potsdam ‐ Deutsches GeoForschungsZentrum GFZ
    Description: RI Fabrice Cotton
    Description: Federal Company for radioactive waste disposal
    Description: https://github.com/MorZieg/FAST_Calibration
    Keywords: ddc:550 ; geomechanics ; uncertainties ; stress state ; modeling ; Bayes
    Language: English
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  • 3
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    Interdecadal Pacific Oscillation in Northern Greenland Dust Concentration Variability During the Last 400 Years (2022)
    Details
    Publication Date: 2023-09-13
    Description: Statistical analysis of reanalysis and observed data reveals that high dust surface mass concentration in northern Greenland is associated with a Pacific Decadal Oscillation like pattern in its negative phase in the North Pacific as well as with La Niña conditions in the tropical Pacific region. The sea surface temperature anomalies in the Pacific realm resemble the Interdecadal Pacific Oscillation (IPO). The associated atmospheric circulation pattern, in the form of a wave‐train from the North Pacific to the Eurasian continent, favors enhanced dust uptake and transport toward the northern Greenland. Similar patterns are associated with a low‐resolution stacked record of five Ca2+ ice cores, that is, ngt03C93.2 (B16), ngt14C93.2 (B18), ngt27C94.2 (B21), GISP2−B, and NEEM‐2011‐S1, from northern Greenland, a proxy for regional dust concentration, during the last 400 years. We argue that northern Greenland ice core dust records could be used as proxies for the IPO and related teleconnections.
    Description: Plain Language Summary: Observational and modeling studies show that, during the observational period, interannual to multidecadal dust concentration variability is related to the dominant modes of climate variability at these time scales. Here we show that Interdecadal Pacific Oscillation (IPO) signal is robustly recorded in low‐resolution dust ice core records from the northern Greenland during the last 400 years. We argue that northern Greenland ice core dust records could be used to put the IPO activity and related teleconnections during the observational period into a long‐term perspective.
    Description: Key Points: Northern Greenland dust concentration variability shows global teleconnections during the instrumental period. The most stable pattern associated with northern Greenland ice core dust variability is the Interdecadal Pacific Oscillation (IPO). Northern Greenland ice core dust records could be used as a complementary source of information about IPO during the past.
    Description: Changing Earth—Sustaining our Future
    Description: Helmholtz Climate Initiative—REKLIM
    Description: https://doi.org/10.1594/PANGAEA.57092
    Description: https://doi.org/10.1594/PANGAEA.57294
    Description: https://doi.org/10.1594/PANGAEA.107285
    Description: https://doi.org/10.1594/PANGAEA.55536
    Description: https://disc.gsfc.nasa.gov/datasets?project=MERRA-2
    Description: https://psl.noaa.gov/data/gridded/data.cobe.html
    Description: https://psl.noaa.gov/data/gridded/data.20thC_ReanV2c.html
    Description: https://www.ncdc.noaa.gov/paleo-search/study/33092
    Description: https://www.wdc-climate.de/ui/entry?acronym=EKF400_v2.0
    Keywords: ddc:551.6 ; dust concentration ; northern Greenland ; Interdecadal Pacific Oscillation ; ice cores
    Language: English
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  • 4
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    Projecting Stratocumulus Transitions on the Albedo—Cloud Fraction Relationship Reveals Linearity of Albedo to Droplet Concentrations (2022)
    Details
    Publication Date: 2023-09-13
    Description: Satellite images show solid marine stratocumulus cloud decks (Sc) that break up over the remote oceans. The Sc breakup is initiated by precipitation and is accompanied by a strong reduction in the cloud radiative effect. Aerosol has been shown to delay the Sc breakup by postponing the onset of precipitation, however its climatic effect is uncertain. Here we introduce a new approach that allows us to re‐cast currently observed cloud cover and albedo to their counterfactual cleaner world, enabling the first estimate of the radiative effect due to delayed cloud breakup. Using simple radiative approximation, the radiative forcing with respect to pre‐industrial times due to delayed Sc breakup is −0.39 W m−2. The radiative effect changes nearly linearly with aerosol due to the droplet concentration control on the cloud cover, suggesting a potentially accelerated warming if the current trend of reduction in aerosol emissions continues.
    Description: Plain Language Summary: The response of cloud cover to aerosol is a climatologically important quantity that has been extremely difficult to estimate. The challenge is that one would need to estimate the fractional area that is currently overcast, but which would have been partly overcast in a cleaner atmosphere. Global climate models (GCMs) are one tool to address such a problem. They allow one to change aerosol levels and to evaluate the cloud response. However, representation of warm, low‐level cloud processes, and in particular aerosol‐cloud interactions in GCMs, is inadequate. Here we introduce an observational method that allows us to re‐cast the currently observed cloud cover and albedo of oceanic warm clouds to their counterfactual state in a cleaner world. We find a linear relationship between the cloud radiative effect and droplet concentration. If we continue to experience a decrease in aerosol emissions then we anticipate a reduction in the aerosol‐cloud radiative effect. The global annual radiative forcing associated with anthropogenic aerosol delaying closed cell breakup is found to be −0.39 W m−2.
    Description: Key Points: A simple model is presented to describe closed cell breakup by initiation of precipitation. The model demonstrates that the global annual radiative effect due to delayed closed cells breakup changes nearly linearly with emissions. The linearity emerges from the nearly linear relationship between cloud cover and albedo.
    Description: German Research Foundation
    Description: Department of Energy's Atmospheric System Research
    Description: Royal Society University Research Fellowship
    Description: https://ladsweb.modaps.eosdis.nasa.gov/archive/allData/61/MOD06_L2/
    Description: https://ceres-tool.larc.nasa.gov/ord-tool/jsp/SSF1degEd41Selection.jsp
    Description: https://doi.org/10.24381/cds.bd0915c6
    Description: https://doi.org/10.5281/zenodo.7072605
    Keywords: ddc:551.5 ; cloud radiative effect ; stratocumulus ; aerosol cloud interactions ; transitions ; closed cells ; open cells
    Language: English
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  • 5
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    Hydrogen Diffusion in Clinopyroxene at Low Temperatures (195°C–400°C) and Consequences for Subsurface Processes (2022)
    Details
    Publication Date: 2023-09-14
    Description: Studying diffusion of hydrogen in nominally anhydrous minerals, like clinopyroxene, at low temperatures is a challenging task due to experimental and analytical difficulties. In this study, to overcome these problems we have produced H concentration gradients in single crystals of natural diopsidic clinopyroxene by ion implantation and measured the nanoscale profiles before and after diffusion anneals using Nuclear Resonance Reaction Analysis. These steps allowed us to conduct experiments at temperatures between 195°C and 400°C. Obtained diffusion rates show a consistent Arrhenius relation D〈sub〉H〈/sub〉= 5.47(±13.98) · 10−8 · exp (−115.64(±11.5) kJ mol〈sup〉−1〈/sup〉/RT) m〈sup〉2〈/sup〉s〈sup〉−1〈/sup〉. Notably, our results lie well within the range of extrapolations from high temperature experiments (≥600°C) of previous studies. This implies that fast diffusion of hydrogen (compared to other elements) extends to low temperatures. We used these results in a non‐isothermal diffusion model that simulates the ascent of crystals (0.5, 1.0, and 2.0 mm) along two representative P‐T‐paths from 600°C to 100°C, to assess potential re‐equilibration of H contents in clinopyroxene at low temperatures. Our model highlights the need to carefully consider boundary conditions, which are a function of P‐T‐f O〈sub〉2〈/sub〉, that control the concentration gradient at the crystal's rim. The results from this model help to assess, as a function of crystal size and cooling rate, when re‐equilibration must be considered.
    Description: Key Points: Diffusion rates of hydrogen in clinopyroxene in the low temperature range (195°C–400°C) were quantified for the first time. Diffusion coefficients at low temperatures lie within the range of extrapolations from high temperature experiments. Non‐isothermal modeling was applied to evaluate potential re‐equilibration of clinopyroxene crystals at low temperatures.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.7290350
    Keywords: ddc:549 ; diffusion ; hydrogen ; clinopyroxene ; equilibration ; low‐temperature
    Language: English
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  • 6
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    Computational methods for the analysis of climate change communication: Towards an integrative and reflexive approach (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-05
    Description: Computational methods, in particular text‐as‐data or Natural Language Processing (NLP) approaches, have become popular to study climate change communication as a global and large‐scale phenomenon. Scholars have discussed opportunities and challenges of these methods for climate change communication, with some proponents and critics taking strong positions, either embracing the potential of computational methods or critically questioning their value. Mirroring developments in the broader social scientific debate, we aim to bring both sides together by proposing a reflexive, integrative approach for computational research on climate change communication: We reflect on strengths (e.g., making data big and small, nowcasting observations) and weaknesses (e.g., introducing empiricist epistemologies, ignoring biases) of computational approaches. Moreover, we also provide concrete and constructive guidance on when and how to integrate (or not integrate) these methods based on theoretical considerations. We thereby understand computational methods as part of an ever‐increasing, diverse toolbox for analyzing climate change communication.
    Keywords: ddc:304.28 ; big data ; climate change communication ; computational methods ; news media ; social media
    Language: English
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  • 7
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    Minimal Recipes for Global Cloudiness (2022)
    Details
    Publication Date: 2023-12-05
    Description: Clouds are primary modulators of Earth's energy balance. It is thus important to understand the links connecting variabilities in cloudiness to variabilities in other state variables of the climate system, and also describe how these links would change in a changing climate. A conceptual model of global cloudiness can help elucidate these points. In this work we derive simple representations of cloudiness, that can be useful in creating a theory of global cloudiness. These representations illustrate how both spatial and temporal variability of cloudiness can be expressed in terms of basic state variables. Specifically, cloud albedo is captured by a nonlinear combination of pressure velocity and a measure of the low‐level stability, and cloud longwave effect is captured by surface temperature, pressure velocity, and standard deviation of pressure velocity. We conclude with a short discussion on the usefulness of this work in the context of global warming response studies.
    Description: Plain Language Summary: Clouds are important for Earth's climate, because they affect a large portion of the planet's energy balance, and hence its mean temperature. To better understand how the interplay between cloudiness and energy balance would change in a changing climate, a better theoretical understanding of how clouds are distributed over the planet, and how this connects with the state variables of the climate system such as temperature and wind speed, is required. As theoretical understanding is currently limited, in this work we explore the possibility of very simply representing the spatiotemporal distribution of clouds over the whole planet. We believe that these simple representations advance the field in the direction of a conceptual theory of global cloudiness and its impact on the energy balance. We show that the impact of cloudiness on both solar and terrestrial radiation balance can be captured well globally with only a few predictive fields, like surface temperature or vertical wind speed, combined simply and using only three tunable parameters, and without using any supplementary information such as the particular season or location on the planet.
    Description: Key Points: Model fits are performed to the spatiotemporal observed cloudiness over all oceans, using a minimal set of predictors and parameters. Models capture global‐mean, spatial, and most of seasonal variability of cloud radiative effects. Cloud albedo and longwave effect are captured by pressure velocity and its variance, surface temperature, and lower tropospheric stability.
    Description: CONSTRAIN project EU Horizon 2020
    Keywords: ddc:551.5 ; global cloudiness ; energy balance ; cloud controlling factors
    Language: English
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  • 8
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    Deep Learning Based Cloud Cover Parameterization for ICON (2022)
    Details
    Publication Date: 2023-12-05
    Description: A promising approach to improve cloud parameterizations within climate models and thus climate projections is to use deep learning in combination with training data from storm‐resolving model (SRM) simulations. The ICOsahedral Non‐hydrostatic (ICON) modeling framework permits simulations ranging from numerical weather prediction to climate projections, making it an ideal target to develop neural network (NN) based parameterizations for sub‐grid scale processes. Within the ICON framework, we train NN based cloud cover parameterizations with coarse‐grained data based on realistic regional and global ICON SRM simulations. We set up three different types of NNs that differ in the degree of vertical locality they assume for diagnosing cloud cover from coarse‐grained atmospheric state variables. The NNs accurately estimate sub‐grid scale cloud cover from coarse‐grained data that has similar geographical characteristics as their training data. Additionally, globally trained NNs can reproduce sub‐grid scale cloud cover of the regional SRM simulation. Using the game‐theory based interpretability library SHapley Additive exPlanations, we identify an overemphasis on specific humidity and cloud ice as the reason why our column‐based NN cannot perfectly generalize from the global to the regional coarse‐grained SRM data. The interpretability tool also helps visualize similarities and differences in feature importance between regionally and globally trained column‐based NNs, and reveals a local relationship between their cloud cover predictions and the thermodynamic environment. Our results show the potential of deep learning to derive accurate yet interpretable cloud cover parameterizations from global SRMs, and suggest that neighborhood‐based models may be a good compromise between accuracy and generalizability.
    Description: Plain Language Summary: Climate models, such as the ICOsahedral Non‐hydrostatic climate model, operate on low‐resolution grids, making it computationally feasible to use them for climate projections. However, physical processes –especially those associated with clouds– that happen on a sub‐grid scale (inside a grid box) cannot be resolved, yet they are critical for the climate. In this study, we train neural networks that return the cloudy fraction of a grid box knowing only low‐resolution grid‐box averaged variables (such as temperature, pressure, etc.) as the climate model sees them. We find that the neural networks can reproduce the sub‐grid scale cloud fraction on data sets similar to the one they were trained on. The networks trained on global data also prove to be applicable on regional data coming from a model simulation with an entirely different setup. Since neural networks are often described as black boxes that are therefore difficult to trust, we peek inside the black box to reveal what input features the neural networks have learned to focus on and in what respect the networks differ. Overall, the neural networks prove to be accurate methods of reproducing sub‐grid scale cloudiness and could improve climate model projections when implemented in a climate model.
    Description: Key Points: Neural networks can accurately learn sub‐grid scale cloud cover from realistic regional and global storm‐resolving simulations. Three neural network types account for different degrees of vertical locality and differentiate between cloud volume and cloud area fraction. Using a game theory based library we find that the neural networks tend to learn local mappings and are able to explain model errors.
    Description: EC ERC HORIZON EUROPE European Research Council
    Description: Partnership for Advanced Computing in Europe (PRACE)
    Description: NSF Science and Technology Center, Center for Learning the Earth with Artificial Intelligence and Physics (LEAP)
    Description: Deutsches Klimarechenzentrum
    Description: Columbia sub‐award 1
    Description: https://github.com/agrundner24/iconml_clc
    Description: https://doi.org/10.5281/zenodo.5788873
    Description: https://code.mpimet.mpg.de/projects/iconpublic
    Keywords: ddc:551.5 ; cloud cover ; parameterization ; machine learning ; neural network ; explainable AI ; SHAP
    Language: English
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  • 9
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    Using diffraction losses of X‐rays in a single crystal for determination of its lattice parameters as well as for monochromator calibration (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-12-04
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉A way has been developed to measure the unit‐cell parameters of a single crystal just from an energy scan with X‐rays, even when the exact energy of the X‐rays is not well defined due to an error in the pitch angle of the monochromator. The precision of this measurement reaches 〈italic〉da〈/italic〉/〈italic〉a〈/italic〉 ∼ 1 × 10〈sup〉−5〈/sup〉. The method is based on the analysis of diffraction losses of the beam, transmitted through a single crystal (the so‐called `glitch effect'). This method can be easily applied to any transmissive X‐ray optical element made of single crystals (for example, X‐ray lenses). The only requirements are the possibility to change the energy of the generated X‐ray beam and some intensity monitor to measure the transmitted intensity. The method is agnostic to the error in the monochromator tuning and it can even be used for determination of the absolute pitch (or 2gθ) angle of the monochromator. Applying the same method to a crystal with well known lattice parameters allows determination of the exact cell parameters of the monochromator at any energy.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Diffraction losses (glitches) at certain energies of the X‐ray beam, transmitted through a single crystal, can be used for lattice parameters determination as well as for calibrating the monochromator (absolute pitch angle and the unit‐cell parameter).〈boxed-text position="anchor" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:16005775:jsy2ay5590:jsy2ay5590-fig-0001"〉 〈alt-text〉image〈/alt-text〉 〈/graphic〉〈/boxed-text〉〈/p〉
    Keywords: ddc:548 ; X‐ray glitches ; diffraction losses ; unit‐cell parameter ; single‐crystal X‐ray optics ; monochromator calibration
    Language: English
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  • 10
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    The geodynamic and limnological evolution of Balkan Lake Ohrid, possibly the oldest extant lake in Europe (2022)
    Details
    Publication Date: 2023-12-04
    Description: Studies of the upper 447 m of the DEEP site sediment succession from central Lake Ohrid, Balkan Peninsula, North Macedonia and Albania provided important insights into the regional climate history and evolutionary dynamics since permanent lacustrine conditions established at 1.36 million years ago (Ma). This paper focuses on the entire 584‐m‐long DEEP sediment succession and a comparison to a 197‐m‐long sediment succession from the Pestani site ~5 km to the east in the lake, where drilling ended close to the bedrock, to unravel the earliest history of Lake Ohrid and its basin development. 26Al/10Be dating of clasts from the base of the DEEP sediment succession implies that the sedimentation in the modern basin started at c. 2 Ma. Geophysical, sedimentological and micropalaeontological data allow for chronological information to be transposed from the DEEP to the Pestani succession. Fluvial conditions, slack water conditions, peat formation and/or complete desiccation prevailed at the DEEP and Pestani sites until 1.36 and 1.21 Ma, respectively, before a larger lake extended over both sites. Activation of karst aquifers to the east probably by tectonic activity and a potential existence of neighbouring Lake Prespa supported filling of Lake Ohrid. The lake deepened gradually, with a relatively constant vertical displacement rate of ~0.2 mm a−1 between the central and the eastern lateral basin and with greater water depth presumably during interglacial periods. Although the dynamic environment characterized by local processes and the fragmentary chronology of the basal sediment successions from both sites hamper palaeoclimatic significance prior to the existence of a larger lake, the new data provide an unprecedented and detailed picture of the geodynamic evolution of the basin and lake that is Europe’s presumed oldest extant freshwater lake.
    Keywords: ddc:551 ; Balkan Peninsula ; Lake Ohrid ; DEEP sediment succession ; Pestani succession ; evolutionary dynamics ; regional climate history
    Language: English
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  • 11
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    Central Mediterranean tephrochronology between 313 and 366 ka: New insights from the Fucino palaeolake sediment succession (2022)
    Leicher, Niklas ; Giaccio, Biagio ; Pereira, Alison ; [et al.]
    Details
    Publication Date: 2023-12-04
    Description: Thirty‐two tephra layers were identified in the time‐interval 313–366 ka (Marine Isotope Stages 9–10) of the Quaternary lacustrine succession of the Fucino Basin, central Italy. Twenty‐seven of these tephra layers yielded suitable geochemical material to explore their volcanic origins. Investigations also included the acquisition of geochemical data of some relevant, chronologically compatible proximal units from Italian volcanoes. The record contains tephra from some well‐known eruptions and eruptive sequences of Roman and Roccamonfina volcanoes, such as the Magliano Romano Plinian Fall, the Orvieto–Bagnoregio Ignimbrite, the Lower White Trachytic Tuff and the Brown Leucitic Tuff. In addition, the record documents eruptions currently undescribed in proximal (i.e. near‐vent) sections, suggesting a more complex history of the major eruptions of the Colli Albani, Sabatini, Vulsini and Roccamonfina volcanoes between 313 and 366 ka. Six of the investigated tephra layers were directly dated by single‐crystal‐fusion 40Ar/39Ar dating, providing the basis for a Bayesian age–depth model and a reassessment of the chronologies for both already known and dated eruptive units and for so far undated eruptions. The results provide a significant contribution for improving knowledge on the peri‐Tyrrhenian explosive activity as well as for extending the Mediterranean tephrostratigraphical framework, which was previously based on limited proximal and distal archives for that time interval.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Italian Ministry of Education, University and Research
    Description: https://doi.org/10.26022/IEDA/112322
    Keywords: ddc:552.2 ; Fucino Basin ; palaeolake sediment succession ; tephra
    Language: English
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  • 12
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    Young magmatism and Si‐rich melts on Mars as documented in the enriched gabbroic shergottite NWA 6963 (2022)
    Details
    Publication Date: 2023-11-28
    Description: Enriched shergottites contain interstitial Si‐rich mesostasis; however, it is unclear whether such mesostasis is formed by impact or magmatic processes. We use laser ablation multicollector inductively coupled plasma mass spectrometry U–Pb measurements of minerals within the interstitial Si‐rich mesostasis and of merrillite within the coarse‐grained groundmass of Martian‐enriched gabbroic shergottite Northwest Africa (NWA) 6963. The date derived of tranquillityite, Cl‐apatite, baddeleyite, and feldspar from the Si‐rich mesostasis is 172.4 ± 6.1 Ma, and the derived merrillite date is 178.3 ± 10.6 Ma. We conclude, based on textural observation, that merrillite is a late magmatic phase in NWA 6963, that it was not produced by shock, and that its U–Pb‐system was not reset by shock. The indistinguishable dates of the gabbroic merrillite and the minerals within the Si‐rich mesostasis in NWA 6963 indicate that the Si‐rich mesostasis represents a late‐stage differentiated melt produced in the final phase of the magmatic history of the gabbroic rock and not a shock melt. This can likely be transferred to similar Si‐rich mesostases in other enriched shergottites and opens the possibility for investigations of Si‐rich mesostasis in enriched shergottites to access their magmatic evolution. Our results also provide a crystallization age of 174 ± 6 Ma (weighted average) for NWA 6963.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Dr. Rolf M. Schwiete Stiftung http://dx.doi.org/10.13039/501100020027
    Keywords: ddc:552 ; Mars ; shergottites ; mesostasis
    Language: English
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  • 13
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    Der Untere Muschelkalk im Raum Godendorf – Kersch – Udelfangen/Südeifel (2022)
    Details
    Publication Date: 2023-11-28
    Description: Der Muschelsandstein im Abbaubetrieb bei Ralingen-Kersch hat neben mächtigen massigen Werksteinen auch vielfältige Fossilien und Lebensspuren geliefert. Sie werden beschrieben und abgebildet. Ein vollmariner, aber dennoch zeitweise sehr flachgründiger Ablagerungsraum bildet sich ab. Innerhalb der gallo-ardennischen Randfazies-Abfolge des Unteren Muschelkalks (mu) der Trier-Luxemburger Bucht markiert die Werksteinzone ein besonderes Intermezzo. Umgeben ist es von den Hinterlassenschaften starker Erdbeben-Ereignisse, die aus dem überregionalen plattentektonischen Geschehen der tieferen Trias resultierten. Die lateral und vertikal hoch variable, z.T. auch lückenhafte mu-Schichtenfolge des Trier-Luxemburgischen Beckenrands wird dargelegt. Sie kann in vier Sequenzen untergliedert werden, die im Wechselspiel tiefer und hoher (relativer) Meeresspiegelstände entstanden. Nicht nur eustatische Gegebenheiten, sondern vor allem auch tektonische Ereignisse waren dabei prägend. Zwei besonders stark regressive Zeitintervalle sind weiträumig durch die akzentuierte Vorschüttung terrigener Sande und Tone und durch basale Schichtlücken gekennzeichnet. Auch deutliche Transgressionsereignisse mit weitem Onlap sind litho- und biofaziell nachzuvollziehen. Anhand der Fazies- und Mächtigkeitsmuster der einzelnen Sequenzen werden ihre unterschiedlichen Subsidenzmuster rekonstruiert und erläutert. Sie belegen die Wichtigkeit von vertikalen Schollenbewegungen, wie es ähnlich auch schon im Buntsandstein der Fall gewesen war. Dies erweist sich hier am Westrand des mitteleuropäischen Beckens ebenso wie im östlichen Beckenrandbereich in Polen. Unterstützt durch die sequenzstratigraphische Methodik ergibt sich nunmehr eine genauere bio- und – vor allem – lithostratigraphische Interngliederung, die eine verbesserte Korrelation mit der mu-Schichtenfolge (in der Westpfalz und) im hessischen und mitteldeutschen Beckeninneren erlaubt. Der Schichtbereich der Werksteinzone von Kersch entspricht der Terebratelzone. Hier im Trier-Luxemburgischen Randbecken ist er als tektonisch initiierter Tiefstands- Systemtrakt (LST) oberhalb einer Sequenzgrenze zu bewerten.
    Description: Abstract: The succession of the Muschelsandstein in the quarry near Ralingen-Kersch has yielded thick and massive stones (freestones) as well as numerous ichnospecies and other fossils. They are described and illustrated here. A fully marine, but nevertheless temporary shallow sedimentation area is documented. This succession (Werksteinzone) marks a very special intermezzo within the local gallo-ardennic border facies of the Lower Muschelkalk (mu). It is surrounded by the remnants of strong seismic events, which resulted from supraregional plate tectonics in lower Triassic. The whole mu-succession of the basin margin around here is described. It is laterally and vertically varying and regionally somewhat incomplete. Now it can be separated into four stratigraphic sequences, which generated during the interplay of low and high (relative) sea levels. Not only eustatic circumstances but mainly tectonic events had been important. Two intervals of strong regressions are indicated by widely spread terrigenous sands and clays and by gaps in the geologic record. Remarkably onlapping transgressive episodes can be traced as well, by litho- and biofacial properties. The respective sequences show individual patterns of lithofacies and thickness. By that their subsidence patterns can be reconstructed and explained genetically. They prove the importance of vertical tectonics, just as in the preceding Buntsandstein. This can be observed here at the western margin of the mid european basin as well as at the eastern margin area in Poland. Supported by sequence stratigraphic means a more detailed internal division is possible, which allows a better correlation to the mu-succession (in western Palatinate and) in the inner basinal areas of Hesse and Central Germany. The stratigraphic range of the Werksteinzone in Kersch corresponds to the Terebratelzone of the inner basin. Here in the individually conditioned Trier-Luxemburg basin area it can be interpreted as a Lowstand Systems Tract (LST) overlying a tectonically induced sequence boundary.
    Description: 1. Einführung 2. Lithostratigraphie des Unteren Muschelkalks im Untersuchungsgebiet 3. Bio- und Ichnofazies bei Kersch 4. Seismite im Unteren Muschelkalk 5. Die Beckenentwicklung und Sequenzstratigraphie des Unteren Muschelkalks der Trier- Luxemburger Bucht im überregionalen Vergleich 5.1 Vorbemerkungen 5.2 mu1-Sequenz (M1a-Sequenz) 5.3 mu2-Sequenz (M1b-Sequenz) 5.4 Grenzbereich mu2-/mu3-Sequenz 5.5 mu3-Sequenz (M1c-Sequenz) 5.6 mu4-Sequenz (M1d-Sequenz) und der mu/mm-Grenzbereich Schriften
    Description: research
    Keywords: ddc:554.3 ; Muschelkalk ; Eifel ; Lithostratigraphie ; Sequenzstratigraphie ; Fische ; TK 6205
    Language: German
    Type: doc-type:article , publishedVersion
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  • 14
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    Large‐scale mass movements recorded in the sediments of Lake Hallstatt (Austria)–evidence for recurrent natural hazards at a UNESCO World Heritage site (2022)
    Lauterbach, Stefan ; Strasser, Michael ; Kowarik, Kerstin ; [et al.]
    Details
    Publication Date: 2023-11-27
    Description: The Bronze to Iron Age underground salt mining complex of Hallstatt (Austria) is widely recognised for its cultural importance and wealth of archaeological artefacts. However, while the daily life in the salt mines is archaeologically well documented and environmental effects of the mining activity have been investigated recently, the impact of natural hazards on the prehistoric mining community is still poorly understood. For instance, while it is well established that the prehistoric underground mines have repeatedly been destroyed by large‐scale mass movements, only little is known about the characteristics and extent of these events as well as about mass‐movement recurrence during more recent times. To shed light on past mass‐movement activity in the vicinity of the Hallstatt salt mines, we investigated sediment cores from adjacent Lake Hallstatt. Within the regular lake sediments we identified three large‐scale event deposits, which are interpreted to originate from spontaneous or seismically induced mass movements in the mid‐19th and late 9th century ce and the mid‐4th century bce. While the age of the latter event is in good agreement with the abandonment of the famous Iron Age cemetery at Hallstatt, the younger events indicate that large‐scale mass movements also occurred repeatedly during the Common Era.
    Description: Freunde des Naturhistorisches Museums Wien
    Description: Austrian Science Fund http://dx.doi.org/10.13039/501100002428
    Description: Austrian Academy of Sciences
    Description: German Archaeological Institute
    Keywords: ddc:551.3 ; Archaeology ; European Alps ; lake sediments ; mass movements ; prehistoric mining
    Language: English
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  • 15
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    Seismic and Tsunamigenic Characteristics of a Multimodal Rupture of Rapid and Slow Stages: The Example of the Complex 12 August 2021 South Sandwich Earthquake (2022)
    Details
    Publication Date: 2023-11-27
    Description: On 12 August 2021, a 〉220 s lasting complex earthquake with M〈sub〉w〈/sub〉 〉 8.2 hit the South Sandwich Trench. Due to its remote location and short interevent times, reported earthquake parameters varied significantly between different international agencies. We studied the complex rupture by combining different seismic source characterization techniques sensitive to different frequency ranges based on teleseismic broadband recordings from 0.001 to 2 Hz, including point and finite fault inversions and the back‐projection of high‐frequency signals. We also determined moment tensor solutions for 88 aftershocks. The rupture initiated simultaneously with a rupture equivalent to a M〈sub〉w〈/sub〉 7.6 thrust earthquake in the deep part of the seismogenic zone in the central subduction interface and a shallow megathrust rupture, which propagated unilaterally to the south with a very slow rupture velocity of 1.2 km/s and varying strike following the curvature of the trench. The slow rupture covered nearly two‐thirds of the entire subduction zone length, and with M〈sub〉w〈/sub〉 8.2 released the bulk of the total moment of the whole earthquake. Tsunami modeling indicates the inferred shallow rupture can explain the tsunami records. The southern segment of the shallow rupture overlaps with another activation of the deeper part of the megathrust equivalent to M〈sub〉w〈/sub〉 7.6. The aftershock distribution confirms the extent and curvature of the rupture. Some mechanisms are consistent with the mainshocks, but many indicate also activation of secondary faults. Rupture velocities and radiated frequencies varied strongly between different stages of the rupture, which might explain the variability of published source parameters.
    Description: Plain Language Summary: The earthquake of 12 August 2021 along the deep‐sea trench of the South Sandwich Islands in the South Atlantic reached a magnitude of 8.2 and triggered a tsunami. The automatic earthquake parameter determination of different agencies showed very different results shortly after the earthquake and partially underestimated the tsunami potential of the earthquake. A possible reason was the complex rupture process and that the tsunami was generated by a long and shallow slow slip rupture sandwiched between more conventional fast slip subevents at its northern and southern ends. In addition, the fault surface, which extended over 450 km, was highly curved striking 150°–220°. We investigated the different components of the seismic wavefields in different frequency ranges and with different methods. The analysis shows how even complex earthquakes can be deciphered by combining analyzing methods. The comparison with aftershocks and the triggered tsunami waves confirms our model that explains the South Sandwich rupture by four subevents in the plate boundary along the curved deep‐sea trench. Here, the depth, rupture velocities, and slip on each segment of the rupture vary considerably. The method can also be applied to other megathrust earthquakes and help to further improve tsunami warnings in the future.
    Description: Key Points: A combination of multiple approaches, inversion setups, and frequency ranges deciphered the complex earthquake of 2021 South Sandwich. The rupture consisted of four subevents with the largest occurring as a shallow slow rupture parallel to the South Sandwich Trench. Forward modeling proves that the large, shallow thrust subevent caused the recorded tsunami.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Agencia Nacional de Investigación y Desarrollo http://dx.doi.org/10.13039/501100020884
    Description: https://ds.iris.edu/wilbert3/find_event
    Description: https://www.usgs.gov/natural-hazards/earthquake-hazards/lists-maps-and-statistics
    Description: http://www.ioc-sealevelmonitoring.org/
    Description: https://doi.org/10.7289/V5C8276M
    Description: https://www.gfz-potsdam.de/en/software/tsunami-wave-propagations-easywave
    Keywords: ddc:551.22 ; 2021 South Sandwich Earthquake ; seismic characteristics ; tsunamigenic characteristics
    Language: English
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  • 16
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    Carbonate platform drowning caught in the act: The sedimentology of Saya de Malha Bank (Indian Ocean) (2022)
    Betzler, Christian ; Lindhorst, Sebastian ; Reijmer, John J. G. ; [et al.]
    Details
    Publication Date: 2023-11-27
    Description: Mesophotic reefs, hardgrounds and current‐controlled pelagic to hemipelagic carbonates are facies marking carbonate platform drowning successions, irrespective of the factors controlling this evolution. A modern analogue of a carbonate platform in a state of drowning, where these facies occur has not been properly reported on to date. In the present study, the sedimentary environments of the Saya de Malha Bank are characterized using a multi‐disciplinary approach including sedimentology, hydroacoustics, seismics and oceanography. The Saya de Malha Bank edifice with a surface of 40 808 km〈sup〉2〈/sup〉 is located in the tropical Indian Ocean and lies in a water depth of 8 to 300 m extending from the surrounding more than 2000 m deep ocean floor, with no reef reaching the sea surface. Mesophotic coral and red algal facies co‐exist with hemipelagic and bioclastic sands, together with a hardground. Ocean currents and internal waves are identified as major sedimentological controlling factors in the absence of elevated nutrient influx. Many features distributed along the present‐day Saya de Malha Bank were described from studies presenting fossil examples of carbonate platform drowning. The results herein can therefore be applied to other drowning examples, in some cases allowing for more accurate interpretation of the stratigraphic record.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:552.58 ; Internal waves, Mascarene Plateau ; mesophotic reefs ; South Equatorial Current
    Language: English
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  • 17
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    Ingenieurgeologische Klassifizierung der Locker-, Halbfest- und Festgesteine von Rheinland-Pfalz (2022)
    Details
    Publication Date: 2023-12-06
    Description: Für das Bundesland Rheinland-Pfalz wurden erstmals Ingenieurgeologische Klassen für den Untergrund aufbauende Böden und Gesteine entwickelt. Grundlage hierfür ist die lithostratigraphische Generallegende aller geologischen Einheiten von Rheinland-Pfalz. Insgesamt wurden 21 Ingenieurgeologische Klassen für Lockergesteine, Halbfestgesteine und Festgesteine definiert. Bei der Entwicklung wurden rheinland-pfälzische Besonderheiten des geologischen Untergrunds berücksichtigt. Dies betrifft insbesondere die im Bundesland flächig verbreiteten Vulkanite. Mit den Ingenieurgeologischen Klassen sollen grundsätzliche flächenhafte Aussagen zum Baugrund (Bebaubarkeit) sowie zu verschiedenen Untergrundgefahren ermöglicht werden. Dies betrifft insbesondere die Anfälligkeiten des Untergrundes gegenüber Rutschungen, Setzungen, der Quell-/ Schrumpfempfindlichkeit, Erdfällen und der Verwitterung sowie das Vorhandensein organischer Anteile. Der Beitrag enthält ein erstes Beispiel für eine Ingenieurgeologische Karte und eine Karte der Rutschungsanfälligkeit für ein Gebiet im Mainzer Becken.
    Description: Abstract: For the first time engineering geological classes for the subsoils and rocks were developed for the federal state of Rhineland-Palatinate. The basis for this is the lithostratigraphic general legend of all geological units of Rhineland-Palatinate. A total of 21 engineering geological classes were defined for unconsolidated rocks, semisolidated rocks and solid rocks. Rhineland-Palatinate specifics of the geological subsurface were taken into account during the development. This concerns in particular the volcanic rocks which are widespread in the federal state. The engineering geology classes are intended to enable basic area-related statements to be made on the subsoil (buildability) as well as on various subsoil hazards. This concerns in particular the susceptibility of the subsoil to landslides, subsidence, swelling/shrinkage sensitivity, sinkholes and weathering as well as the presence of organic components. The paper contains a first example of an engineering geology map and a landslide susceptibility map for an area in the Mainz Basin.
    Description: research
    Keywords: ddc:554.3 ; Rheinland-Pfalz ; Ingenieurgeologie ; Baugrund
    Language: German
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  • 18
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    On the Ridging of the South Atlantic Anticyclone Over South Africa: The Impact of Rossby Wave Breaking and of Climate Change (2022)
    Details
    Publication Date: 2023-11-16
    Description: Ridging South Atlantic Anticyclones contribute an important amount of precipitation over South Africa. Here, we use a global coupled climate model and the ERA5 reanalysis to separate for the first time ridging highs (RHs) based on whether they occur together with Rossby wave breaking (RWB) or not. We show that the former type of RHs are associated with more precipitation than the latter type. The mean sea level pressure anomalies caused by the two types of RHs are characterized by distinct patterns, leading to differences in the flow of moisture‐laden air onto land. We additionally find that RWB mediates the effect of climate change on RHs during the twenty‐first century. Consequently, RHs occurring without RWB exhibit little change, while those occurring with RWB contribute more precipitation over the southern and less precipitation over the northeastern South Africa in the future.
    Description: Plain Language Summary: The high pressure system located above the South Atlantic Ocean occasionally extends eastward over South Africa, leading to winds that blow onshore and carry moisture from the warm waters of the Southwest Indian Ocean to the coast. These events, termed ridging highs (RHs), bring an important contribution to precipitation over the southern and eastern parts of South Africa. Their occurrence is related to the propagation and breaking of atmospheric waves at the boundary between the troposphere and the stratosphere. This study categorizes RHs based on the behavior of atmospheric waves above and shows that events that are accompanied by wave breaking result in more precipitation over South Africa. In addition, model simulations are used to investigate the impact of climate change during the twenty‐first century on RHs and the associated precipitation. Although the model predicts that in total South Africa will experience drier conditions in the future, RHs contribute to this drying trend only in the northeastern part of the country. In the southern part of South Africa, the model simulates that RHs will bring more precipitation in the future.
    Description: Key Points: Ridging South Atlantic Anticyclones are accompanied by Rossby wave breaking (RWB) aloft in 44% of the cases. Ridging highs that are accompanied by RWB lead to more precipitation over South Africa than those that are not. Ridging highs bring more precipitation over the southern and less precipitation over the northeastern part of South Africa in the future.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Water Research Commission http://dx.doi.org/10.13039/501100004424
    Description: https://doi.org/10.5281/zenodo.6523956
    Description: https://doi.org/10.24381/cds.bd0915c6
    Description: https://psl.noaa.gov/data/gridded/data.cpc.globalprecip.html
    Keywords: ddc:551.6 ; ridging highs ; Rossby wave breaking ; climate change ; climate modeling ; South African precipitation
    Language: English
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  • 19
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    Cenozoic Proxy Constraints on Earth System Sensitivity to Greenhouse Gases (2022)
    Details
    Publication Date: 2023-11-16
    Description: The long‐term extent of the Earth system response to anthropogenic interference remains uncertain. However, the geologic record offers insights into this problem as Earth has previously cycled between warm and cold intervals during the Phanerozoic. We present an updated compilation of surface temperature proxies for several key time intervals to reconstruct global temperature changes during the Cenozoic. Our data synthesis indicates that Earth’s surface slowly cooled by ca. 9°C during the early Paleogene to late Neogene and that continent‐scale ice sheets developed after global temperature dropped to less than 10°C above preindustrial conditions. Slow cooling contrasts with the steep decrease in combined radiative forcing from past CO〈sub〉2〈/sub〉 concentrations, solar luminosity, and ocean area, which was close to preindustrial levels even as Earth remained in a much warmer state. From this, we infer that the Earth system was less sensitive to greenhouse gas forcing for most of the Cenozoic and that sensitivity must have increased by at least a factor of 2 during the Plio‐Pleistocene. Our results imply that slow feedbacks will raise global surface temperatures by more than 3°C in the coming millennia, even if anthropogenic forcing is stabilized at the present‐day value (2 W/m〈sup〉2〈/sup〉), and that their impact will diminish with further warming.
    Description: Plain Language Summary: It is not well known how much Earth’s surface temperature will change over the next few millennia as a result of increasing atmospheric CO〈sub〉2〈/sub〉 concentrations. This is because we still have a limited understanding of many slow climate feedback mechanisms activated by climate change that will become important in the future. Most climate models project eventual global warming of 3–4°C for doubled CO〈sub〉2〈/sub〉 concentration but exclude many slow climate feedbacks, such as shrinking ice sheets. The distant (geologic) past provides additional clues about the future because the climate system and all of its feedbacks were in equilibrium with naturally elevated CO〈sub〉2〈/sub〉. Using up‐to‐date geologic information of the last 50 million years, we find that Earth’s climate history is best described by a switch from a moderate sensitivity, close to that found in climate models, to a much higher sensitivity in the last 3 million years. If Earth behaves the same way today as it has done in the past, melting ice sheets, natural aerosols, and shifting vegetation patterns will slowly continue to raise global warming above the 2°C target during the next few thousand years even if the human contribution does not increase any further.
    Description: Key Points: Large compilation of Cenozoic paleoclimate proxies was analyzed. Paleogene and Neogene were dominated by Earth system sensitivity of 4°C but sensitivity must have increased in the Plio‐Pleistocene. High Earth system sensitivity stresses the importance of climate change mitigation over adaptation.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5880/GFZ.3.3.2022.005
    Keywords: ddc:551.7 ; Cenozoic ; surface temperature proxies ; atmospheric carbon dioxide concentrations
    Language: English
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  • 20
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    Quantifying electron cascade size in various irradiated materials for free‐electron laser applications (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-12-12
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Studying electron‐ and X‐ray‐induced electron cascades in solids is essential for various research areas at free‐electron laser facilities, such as X‐ray imaging, crystallography, pulse diagnostics or X‐ray‐induced damage. To better understand the fundamental factors that define the duration and spatial size of such cascades, this work investigates the electron propagation in ten solids relevant for the applications of X‐ray lasers: Au, B〈sub〉4〈/sub〉C, diamond, Ni, polystyrene, Ru, Si, SiC, Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉 and W. Using classical Monte Carlo simulation in the atomic approximation, we study the dependence of the cascade size on the incident electron or photon energy and on the target parameters. The results show that an electron‐induced cascade is systematically larger than a photon‐induced cascade. Moreover, in contrast with the common assumption, the maximal cascade size does not necessarily coincide with the electron range. It was found that the cascade size can be controlled by careful selection of the photon energy for a particular material. Photon energy, just above an ionization potential, can essentially split the absorbed energy between two electrons (photo‐ and Auger), reducing their initial energy and thus shrinking the cascade size. This analysis suggests a way of tailoring the electron cascades for applications requiring either small cascades with a high density of excited electrons or large‐spread cascades with lower electron densities.〈/p〉
    Description: 〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Studying electron‐ and X‐ray‐induced electron cascades in solids is essential for various research areas at free‐electron laser facilities, such as X‐ray imaging, crystallography, pulse diagnostics or X‐ray‐induced damage. To better understand the fundamental factors that define the duration and spatial size of such cascades, this work investigates the electron propagation in ten solids relevant for the applications of X‐ray lasers. Using classical Monte Carlo simulation in the atomic approximation, the dependence of the cascade size on the incident electron or photon energy and on the target parameters is studied.〈boxed-text position="anchor" content-type="graphic" xml:lang="en"〉〈graphic position="anchor" id="jats-graphic-1" xlink:href="urn:x-wiley:16005775:jsy2gb5123:jsy2gb5123-fig-0001"〉 〈/graphic〉〈/boxed-text〉〈/p〉
    Keywords: ddc:548 ; electron cascades ; X‐ray free‐electron lasers ; Monte Carlo ; photon‐induced cascade ; electron transport
    Language: English
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  • 21
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    Fine‐Sediment Erosion and Sediment‐Ribbon Morphodynamics in Coarse‐Grained Immobile Beds (2022)
    Details
    Publication Date: 2023-10-26
    Description: In rivers, fine sediments are often transported over immobile coarse grains. With low sediment supply, they tend to aggregate in longitudinal ribbons. Yet, the long‐term evolution of such ribbons and the influence of immobile grains on the erosion of fine sediments are still not well understood. Flume experiments without sediment supply were therefore performed to investigate the erosion of an initially uniform fine‐sediment bed covering an immobile bed of staggered spheres through topographic and flow measurements. The topographic measurements yielded the spheres' protrusion above the fine sediment (P) and revealed long‐lived ribbons with ridges and troughs. The ridges are the main long‐term sediment source as the troughs are quickly eroded to a stable bed level resulting from the spheres' sheltering. The ridges stabilize with a spacing of 1.3 effective water depths, their number resulting from the integer number of wavelengths fitting into the effective channel width which excludes side‐wall accumulations. The ridges' erosion is damped by the local upflow of secondary current cells, which displaces the strongest sweep events above the bed. The upflow intensity is controlled by the ridges' height for low P, while for high P by the lateral roughness heterogeneity. The trends in erosion rates over ridges and troughs are similar and characterized by the following sequence of four regimes with increasing P: a drag sheltering, a turbulence‐enhancement, a wake‐interference sheltering, and a skimming‐flow sheltering regime. The critical P levels at the transitions are independent of the flow above the canopy, depending only on the geometrical configuration of the immobile bed.
    Description: Key Points: Four erosive regimes are identified: drag sheltering, turbulence‐enhancement, wake‐interference sheltering and skimming‐flow sheltering. Secondary currents influence the momentum redistribution but the erosive behavior is controlled by the protrusion of the immobile grains. The sediment‐ribbon spacing is about 1.3 effective water depths.
    Description: Landesgraduiertenförderung of the Land Baden‐Württemberg
    Description: Graduate School for Climate and Environment, KIT
    Description: https://doi.org/10.5281/zenodo.5787371
    Keywords: ddc:550.724 ; sediment erosion ; rough beds ; sediment ribbons ; secondary currents ; open‐channel ; ridge morphology
    Language: English
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  • 22
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    Partial melting and reaction along deformation features in plagioclase (2022)
    Details
    Publication Date: 2023-10-26
    Description: Geological processes involving deformation and/or reactions are highly influenced by the rock grain size, especially if diffusion‐controlled processes take place such as metamorphic reactions and diffusion creep. Although many processes, inducing grain‐size reduction, are documented and understood at relatively high stresses and low temperatures (e.g., cataclasis) as well as at lower stress and higher temperature conditions (e.g., bulging and subgrain rotation), deformation twinning, a plastic deformation mechanism active in various minerals at lower temperatures, has been neglected as nucleation site for melting and reaction and thus as a cause for grain‐size reduction so far. We conducted experiments on natural plagioclase‐bearing aggregates at 2.5 to 3 GPa confining pressure and temperatures of 700°C to 950°C using two different deformation apparatus, a deformation multianvil apparatus (DDIA) and a Griggs press, as well as a piston‐cylinder apparatus. Regardless of the apparatus type, we observe the breakdown of plagioclase into an eclogite‐facies paragenesis, which is associated with partial melting in the high temperature domain of the eclogite facies. Partial melting mostly takes place along the grain and interphase boundaries. However, several melt patches or plagioclase decomposition products coincide with the occurrence of deformation twins and grain‐scale microcracking in plagioclase indicating intracrystalline melting and reaction in addition to melting and reaction along grain and interphase boundaries. In the present study, we demonstrate how the interplay between brittle microcracking and plastic deformation twinning can cause intracrystalline melting and/or reaction, which has the potential to lower the effective grain size of plagioclase‐rich rocks and thus impacts their reactivity and deformation behaviour.
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: Alexander von Humboldt‐foundation http://dx.doi.org/10.13039/100005156
    Keywords: ddc:549 ; ddc:552.4 ; continental crust ; deformation twinning ; partial melting ; plagioclase deformation ; semibrittle regime
    Language: English
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  • 23
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    Rare Holocene sediment deposits from Sodmein Playa (Eastern Desert, Egypt)—Stratigraphic assessment and environmental setting (2022)
    Henselowsky, Felix ; Klasen, Nicole ; Timms, Rhys ; [et al.]
    Details
    Publication Date: 2023-11-03
    Description: Sodmein Playa is one of the rare Pleistocene open‐air sites in the Eastern Desert of Egypt. Based on the associated stone artefact material, it could be assigned to the Middle Stone Age/Last Interglacial. However, it has not yet been possible to clarify whether the sediments at the basin originated during the Pleistocene or later during Holocene wet phases. Our integrative approach combining Optically Stimulated Luminescence chronology, and cryptotephra analysis, allows us to link the environmental archive of Sodmein Playa with the site of Sodmein Cave. Sodmein Playa indicates wetter climate conditions starting around 9 ka with a (relative) maximum around 7 ka, in line with the general framework of the Holocene Humid Period in Northeast Africa. Despite the climatic similarity, regional environmental differences can still be identified and the effective available water around Sodmein Playa is reduced. The results are well integrated into the current archaeological knowledge with the change from hunter‐gatherers to herders during the Holocene in the area. Analyses of cryptotephra reveal a wide range of source regions, including Eastern and Central Anatolian, the Azores, and the Aegean, as well as those which remain uncorrelated. A tentative correlation with the Holocene cryptotephra record from Sodmein Cave is established.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551.3 ; Cryptotephra ; Northeast Africa ; OSL ; Playa
    Language: English
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  • 24
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    Linking uplift, erosion, and sedimentation using landscape evolution models: Madagascar since the Late Cretaceous (2022)
    Details
    Publication Date: 2023-12-16
    Description: We present a study to estimate the large‐scale landscape history of a continental margin, by establishing a source‐to‐sink volume balance between the eroding onshore areas and the offshore basins. Assuming erosion as the primary process for sediment production, we strive to constrain a numerical model of landscape evolution that balances the volumes of eroded materials from the continent and that deposited in the corresponding basins, with a ratio imposed for loss of erosion products. We use this approach to investigate the landscape history of Madagascar since the Late Cretaceous. The uplift history prescribed in the model is inferred from elevations of planation surfaces formed at various ages. By fitting the volumes of terrigenous sediments in the Morondava Basin along the west coast and the current elevation of the island, the landscape evolution model is optimized by constraining the erosion law parameters and ratios of sediment loss. The results include a best‐fit landscape evolution model, which features two major periods of uplift and erosion during the Late Cretaceous and the middle to late Cenozoic. The model supports suggestions from previous studies that most of the high topography of the island was constructed since the middle to late Miocene, and on the central plateau the erosion has not reached an equilibrium with the high uplift rates in the late Cenozoic. Our models also indicate that over the geological time scale a significant portion of materials eroded from Madagascar was not archived in the offshore basin, possibly consumed by chemical weathering, the intensity of which might have varied with climate.
    Description: This paper uses a numerical landscape evolution model to reconstruct the topographic history of Madagascar since the Late Cretaceous. The model is optimised by balancing the volumes of onshore erosion and offshore sedimentation; the former is predicted with erosion laws and based on uplift history inferred from elevated planation surfaces. The modelling results suggest a significant volume loss of materials during the process from erosion to sedimentation, which is likely consumed by chemical weathering. image
    Description: https://tel.archives-ouvertes.fr/tel-01865476
    Keywords: ddc:551.3 ; chemical weathering ; erosion ; landscape evolution model ; Madagascar ; sedimentary basin ; source to sink
    Language: English
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  • 25
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    On the representation of atmospheric circulation modes in regional climate models over Western Europe (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-12-16
    Description: Atmospheric circulation is a key driver of climate variability, and the representation of atmospheric circulation modes in regional climate models (RCMs) can enhance the credibility of regional climate projections. This study examines the representation of large‐scale atmospheric circulation modes in Coupled Model Inter‐comparison Project phase 5 RCMs once driven by ERA‐Interim, and by two general circulation models (GCMs). The study region is Western Europe and the circulation modes are classified using the Promax rotated T‐mode principal component analysis. The results indicate that the RCMs can replicate the classified atmospheric modes as obtained from ERA5 reanalysis, though with biases dependent on the data providing the lateral boundary condition and the choice of RCM. When the boundary condition is provided by ERA‐Interim that is more consistent with observations, the simulated map types and the associating time series match well with their counterparts from ERA5. Further, on average, the multi‐model ensemble mean of the analysed RCMs, driven by ERA‐Interim, indicated a slight improvement in the representation of the modes obtained from ERA5. Conversely, when the RCMs are driven by the GCMs that are models without assimilation of observational data, the representation of the atmospheric modes, as obtained from ERA5, is relatively less accurate compared to when the RCMs are driven by ERA‐Interim. This suggests that the biases stem from the GCMs. On average, the representation of the modes was not improved in the multi‐model ensemble mean of the five analysed RCMs driven by either of the GCMs. However, when the best‐performed RCMs were selected on average the ensemble mean indicated a slight improvement. Moreover, the presence of the North Atlantic Oscillation (NAO) in the simulated modes depends also on the lateral boundary conditions. The relationship between the modes and the NAO was replicated only when the RCMs were driven by reanalysis. The results indicate that the forcing model is the main factor in reproducing the atmospheric circulation.
    Keywords: ddc:551.6 ; general circulation model ; large‐scale atmospheric circulation modes ; multi‐model ensemble ; regional climate model ; Western Europe
    Language: English
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  • 26
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    Quantification of Impact‐Induced Melt Production in Numerical Modeling Revisited (2022)
    Details
    Publication Date: 2023-12-16
    Description: Melting and vaporization of rocks in impact cratering is mostly attributed to be a consequence of shock compression. However, other mechanism such as plastic work and decompression by structural uplift also contribute to melt production. In this study we expand the commonly used method to determine shock‐induced melting in numerical models from the peak shock pressure by a new approach to account for additional heating due plastic work and internal friction. We compare our new approach with the straight‐forward method to simply quantify melting from the temperature relative to the solidus temperature at any arbitrary point in time in the course of crater formation. This much simpler method does account for plastic work but suffers from reduced accuracy due to numerical diffusion inherent to ongoing advection in impact crater formation models. We demonstrate that our new approach is more accurate than previous methods in particular for quantitative determination of impact melt distribution in final crater structures. In addition, we assess the contribution of plastic work to the overall melt volume and find, that melting is dominated by plastic work for impacts at velocities smaller than 7.5–12.5 km/s in rocks, depending on the material strength. At higher impact velocities shock compression is the dominating mechanism for melting. Here, the conventional peak shock pressure method provides similar results compared with our new model. Our method serves as a powerful tool to accurately determine impact‐induced heating in particular at relatively low‐velocity impacts.
    Description: Plain Language Summary: During the collision of cosmic bodies such as planets and asteroids on various scales, the involved material is heated such that melting or vaporization can occur. The vast amount of heat is considered to be generated during shock compression, however recent studies found that plastic deformation during decompression also contribute to the heating process. In this study, we introduce a new approach to quantify impact‐induced melting more accurately under consideration of the latter heating mechanisms. We demonstrate that our approach is more accurate than previous attempts and quantify the contribution from plastic work on impact‐induced melting. We systematically study the effect of impact velocity and material strength on melt production and find, that it is dominated by plastic work for impact velocities up to 7.5–12.5 km/s in rocks, depending on the material strength.
    Description: Key Points: We propose an improved method to quantify impact‐induced melt production for rocks. We quantify impact‐induced melt production and separate between heating due to shock compression and plastic work. Melting due to frictional heating (plastic work) dominates over shock melting for impact velocities below 7–13 km/s depending on strength.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Japan Society for the Promotion of Science London http://dx.doi.org/10.13039/501100000646
    Description: http://www.isale-code.de/redmine/projects/isale/wiki/Terms_of_use
    Description: https://doi.org/10.35003/HVTJQD
    Keywords: ddc:550.724 ; impact heating ; numerical modeling ; impact melt ; melt quantification
    Language: English
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  • 27
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    Impact of Parametrizing Microphysical Processes in the Jet and Vortex Phase on Contrail Cirrus Properties and Radiative Forcing (2022)
    Details
    Publication Date: 2023-12-15
    Description: Contrail ice nucleation and ice crystal loss during the vortex phase control ice crystal numbers in young contrails and can have a strong impact on the properties and the life cycle of contrail cirrus. For current soot number emissions, ice nucleation is controlled by the number of emitted soot particles and atmospheric conditions while the vortex phase loss depends predominantly on the nucleated ice crystal numbers and the ambient relative humidity. Initial ice crystal numbers after the vortex phase are close to the emitted soot particle number only for very low ambient temperatures (〈210 K) and for highly ice‐supersaturated conditions. Higher temperatures and lower relative humidities lead to significantly decreased ice crystal numbers. Global climate model simulations show that initial contrail ice crystal numbers per fuel mass are on average 50%–65% decreased relative to the soot number emission index in the extratropics and more in tropics. In the extratropics, this is mainly caused by a high ice crystal loss during the vortex phase and in the (sub)tropics and at lower flight levels by decreased ice nucleation. Simulated ice crystal numbers per newly formed contrail length agree well with in situ measurements over central Europe within the variability of present‐day soot number emissions. Our estimated global mean contrail cirrus radiative forcing (RF) for the year 2006 is 44 (31–49) mWm〈sup〉−2〈/sup〉, around 22% lower than estimated in a previous study. When reducing soot number emissions by 80%, RF decreases by 41%, slightly less than suggested by a recent study.
    Description: Plain Language Summary: Contrail cirrus are known to be a major contribution to the aviation climate impact connected with a large uncertainty. Earlier research has shown that the ice crystal number in newly formed contrails has a large impact on the average contrail cirrus climate impact. But the properties of newly formed contrails are not well captured within the climate models. We have improved the representation of the contrail formation processes in our contrail cirrus module within the ECHAM climate model by including parameterizations for contrail ice nucleation and the ice crystal survival in the vortex phase. We could show that young contrail properties agree well with available campaign measurements over central Europe, given the large variability in soot number emissions, when matching geographical locations, cruise level, and atmospheric variables. The improvements within our contrail cirrus parameterization lead to a decrease in our estimate of contrail cirrus radiative forcing by slightly more than 20% relative to our earlier estimates in which we prescribed constant initial ice crystal numbers. Furthermore, our improved model indicates that the decrease in the contrail cirrus climate impact due to introducing biofuels, which lead to a decrease in soot number emissions, is slightly smaller than estimated earlier.
    Description: Key Points: For current soot emissions, young contrail ice numbers are limited by vortex phase loss in extratropics and ice nucleation in tropics. Modeled young contrail ice crystal numbers agree well with measurements over Europe considering the variability of soot number emissions. Sensitivity of contrail cirrus radiative forcing to soot number emissions decreased if capturing variability in young contrail ice numbers.
    Description: Emission and Climate Impact of Alternative Fuels
    Description: Scientific Steering Committee
    Description: https://zenodo.org/record/6902742
    Description: https://www.qtiplot.com/
    Description: http://ferret.pmel.noaa.gov/Ferret/
    Keywords: ddc:551.5 ; contrail formation ; soot number emissions ; ice crystal numbers ; contrail cirrus properties ; radiative forcing
    Language: English
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    Disk transport rates from Ti isotopic signatures of refractory inclusions (2022)
    Details
    Publication Date: 2023-12-15
    Description: The early solar system was a dynamic period during which the formation of early solids set into motion the process of planet building. Although both astrophysical observations and theoretical modeling demonstrate the presence of widespread transport of material, we lack concrete quantitative constraints on timings, distances, and mechanisms thereof. To trace these transport processes, one needs objects of known early formation times and these objects would need to be distributed throughout parent bodies with known accretion times and distances. Generally, these criteria are met by “regular” (i.e., non–fractionated and unidentified nuclear and excluding hibonite‐rich) Ca‐Al‐rich inclusions (CAIs) as these objects formed very early and close to the young Sun and contain distinctive nucleosynthetic isotope anomalies that permit provenance tracing. However, nucleosynthetic isotopic signatures of such refractory inclusions have so far primarily been analyzed in chondritic meteorites that formed within ~4 AU from the Sun. Here, we investigate Ti isotopic signatures of four refractory inclusions from the ungrouped carbonaceous chondrite WIS 91600 that was previously suggested to have formed beyond ~10 AU from the Sun. We show that these inclusions exhibit correlated excesses in 〈sup〉50〈/sup〉Ti and 〈sup〉46〈/sup〉Ti and lack large Ti isotopic anomalies that would otherwise be indicative of more enigmatic refractory materials with unknown formation ages. Instead, these isotope systematics suggest the inclusions to be genetically related to regular CAIs commonly found in other chondrites that have a broadly known formation region and age. Collectively, this implies that a common population of CAIs was distributed over the inner ~10 AU within ~3.5 Myr, yielding an average (minimum) speed for the transport of millimeter‐scale material in the early solar system of ~1 cm s〈sup〉−1〈/sup〉.
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Lawrence Livermore National Laboratory http://dx.doi.org/10.13039/100006227
    Keywords: ddc:549.112 ; chondritic meteorites ; Ti isotopic signatures ; disk transport processes
    Language: English
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  • 29
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    Zooplankton‐derived dissolved organic matter composition and its bioavailability to natural prokaryotic communities (2022)
    De Corte, Daniele ; Varela, Marta M. ; Louro, Angeles M. ; [et al.]
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-14
    Description: Zooplankton grazing onphytoplankton promotes the release of particulate and dissolved organic matter (DOM) into the water column and therefore plays a key role in organic matter cycling in aquatic systems. Prokaryotes are the main DOM consumers in the ocean by actively remineralizing and transforming it, contributing to its molecular diversification. To explore the molecular composition of zooplankton‐derived DOM and its bioavailability to natural prokaryotic communities, the DOM generated by a mixed zooplankton community in the coastal Atlantic off Spain was used as substrate for a natural prokaryotic community and monitored over a ~ 5‐d incubation experiment. The molecular composition of solid‐phase extracted DOM was characterized via Fourier‐transform ion cyclotron resonance mass spectrometry. After ~ 4 d in the zooplankton‐derived DOM amended incubation, the prokaryotic community demonstrated a 17‐fold exponential increase in cell number. The prokaryotic growth resulted in a reduction in bulk dissolved organic carbon concentration and the zooplankton‐derived DOM was considerably transformed at molecular and bulk elemental levels over the incubation period. The C : N ratio (calculated from the obtained molecular formulae) increased while the functional diversity decreased over the incubation time. In addition, molecular indices pointed to a reduced bioavailability of DOM at the end of the experiment. These findings show that zooplankton excreta are a source of labile organic matter that is quickly metabolized by the prokaryotic community. Therefore, a fraction of carbon is shunted from transfer to secondary consumers similarly to the viral shunt, suggesting that the zooplankton–prokaryotic interactions play an important role in the ocean's carbon cycle.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Xunta de Galicia http://dx.doi.org/10.13039/501100010801
    Keywords: ddc:577.7 ; Spain ; coastal Atlantic ; zooplankton–prokaryotic interactions ; ocean’s carbon cycle
    Language: English
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    Effects of Atlantification and changing sea‐ice dynamics on zooplankton community structure and carbon flux between 2000 and 2016 in the eastern Fram Strait (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-12-14
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The collection of zooplankton swimmers and sinkers in time‐series sediment traps provides unique insight into year‐round and interannual trends in zooplankton population dynamics. These samples are particularly valuable in remote and difficult to access areas such as the Arctic Ocean, where samples from the ice‐covered season are rare. In the present study, we investigated zooplankton composition based on swimmers and sinkers collected by sediment traps at water depths of 180–280, 800–1320, and 2320–2550 m, over a period of 16 yr (2000–2016) at the Long‐Term Ecological Research observatory HAUSGARTEN located in the eastern Fram Strait (79°N, 4°E). The time‐series data showed seasonal and interannual trends within the dominant zooplankton groups including copepoda, foraminifera, ostracoda, amphipoda, pteropoda, and chaetognatha. Amphipoda and copepoda dominated the abundance of swimmers while pteropoda and foraminifera were the most important sinkers. Although the seasonal occurrence of these groups was relatively consistent between years, there were notable interannual variations in abundance, suggesting the influence of various environmental conditions such as sea‐ice dynamic and lateral advection of water masses, for example, meltwater and Atlantic water. Statistical analyses revealed a correlation between the Arctic dipole climatic index and sea‐ice dynamics (i.e., ice coverage and concentration), as well as the importance of the distance from the ice edge on swimmer composition patterns and carbon export.〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Federal Ministry of Education and Research (BMBF)
    Description: Helmholtz‐Gemeinschaft
    Keywords: ddc:577.7 ; eastern Fram Strait ; sea ice dynamics ; zooplankton population dynamics
    Language: English
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    Precipitation Over Southern Africa: Moisture Sources and Isotopic Composition (2022)
    Details
    Publication Date: 2023-12-14
    Description: Southern Africa, with its vast arid to semiarid areas, is considered vulnerable to precipitation changes and amplifying weather extremes. However, during the last 100 ka, huge lakes existed in the currently dry central Kalahari. It has been suggested that these lakes could have existed due to altered atmospheric circulation pattern, leading to an increase in precipitation or to changes in the annual precipitation distribution. Past climate changes are recorded in paleo‐archives, yet, for a proper interpretation of paleo‐records, for example, from sedimentological archives or fossils, it is essential to put them in a context with recent observations. This study’s objective is, therefore, to analyze spatially differing annual precipitation distributions at multiple locations in southern Africa with respect to their stable water isotope composition, moisture transport pathways, and sources. Five different precipitation distributions are identified by end‐member modeling and respective rainfall zones are inferred, which differ significantly in their isotopic compositions. By calculating backward trajectories, different moisture source regions are identified for the rainfall zones and linked to typical circulation patterns. Our results furthermore show the importance of the seasonality, the amount effect, and the traveled distance of the moisture for the general isotopic composition over the entire southern Africa. The identified pattern and relationships can be useful in the evaluation of isotope‐enabled climate models for the region and are potentially of major importance for the interpretation of stable water isotope composition in paleo‐records in future research.
    Description: Key Points: We identified five different annual precipitation distributions in southern Africa that cluster in space and define rainfall zones. Lagrangian source diagnostic shows that the rainfall zones have notably different moisture sources. The isotopic composition differs significantly between rainfall zones.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://nucleus.iaea.org/wiser
    Description: https://doi.pangaea.de/10.1594/PANGAEA.944811
    Description: https://doi.org/10.24381/cds.bd0915c6
    Description: http://iacweb.ethz.ch/staff/sprenger/lagranto/
    Description: https://forobs.jrc.ec.europa.eu/products/glc2000/products.php
    Description: https://doi.org/10.6084/m9.figshare.7504448.v3
    Description: https://doi.org/10.5066/F7J38R2N
    Description: https://cran.r-project.org/bin/windows/base/old/
    Description: https://cran.r-project.org/web/packages/EMMAgeo/index.html
    Description: https://cran.r-project.org/web/packages/party/index.html
    Keywords: ddc:551.5 ; Lagrangian moisture source diagnostic ; stable water isotopes ; precipitation end‐member ; random forest ; annual rainfall distribution ; moisture pathways
    Language: English
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    Impacts of the Desiccation of the Aral Sea on the Central Asian Dust Life‐Cycle (2022)
    Details
    Publication Date: 2023-12-19
    Description: The formation of the Aralkum (Aral Desert), following the severe desiccation of the former Aral Sea since the 1960s, has created what may be regarded as one of the world's most significant anthropogenic dust sources. In this paper, focusing on dust emission and transport patterns from the Aralkum, the dust life‐cycle has been simulated over Central Asia using the aerosol transport model COSMO‐MUSCAT (COnsortium for Small‐scale MOdelling‐MUltiScale Chemistry Aerosol Transport Model), making use of the Global Surface Water data set to take into account the sensitivity to changes in surface water coverage over the region between the 1980s (the “past”) and the 2010s (the “present”). Over a case study 1‐year period, the simulated dust emissions from the Aralkum region increased from 14.3 to 27.1 Tg year〈sup〉−1〈/sup〉 between the past and present, an increase driven solely by the changes in the surface water environment. Of these simulated modern emissions, 14.5 Tg are driven by westerly winds, indicating that regions downwind to the east may be worst affected by Aralkum dust. However a high degree of interannual variability in the prevailing surface wind patterns ensures that these transport patterns of Aralkum dust do not occur every year. Frequent cloud cover poses substantial challenges for observations of Central Asian dust: in the Aralkum, over two‐thirds of the yearly emissions are emitted under overcast skies, dust which may be impossible to observe using traditional satellite or ground‐based passive remote sensing techniques. Furthermore, it is apparent that the pattern of dust transport from the Aralkum under clear‐sky conditions is not representative of the pattern under all‐sky conditions.
    Description: Plain Language Summary: Since the 1960s the Central Asian lake that used to be known as the Aral Sea has almost completely dried out, due to human activity. This environmental disaster has created a new desert known as the Aralkum (the “Aral Desert”), which now has a size of 245 km × 245 km across. Dried lakes such as the Aralkum can be very effective sources of wind‐driven atmospheric dust. The soils of the Aralkum are also contaminated with agricultural chemicals from nearby croplands, making the Aralkum a major regional threat to human health. Using an atmospheric computer model, we explore the consequences of the new Aralkum for the patterns of atmospheric dust and their potential impacts in Central Asia. We find that the new Aralkum has contributed an extra 7% per year to the total dust quantity over Central Asia, however due to thick cloud cover over two thirds of this dust from the Aralkum cannot be seen by Earth‐observing satellites. The wind patterns over the Aralkum vary from year to year, so while our simulations predict that most of the Aralkum's dust is transported to the east during the simulation year, during other years plenty more dust will be transported elsewhere.
    Description: Key Points: The impact of changes in surface water coverage over the Aralkum (the former Aral Sea) for dust emission and transport is investigated. There is a high degree of interannual variability in the directions of dust‐emitting winds over the Aralkum. Over two thirds of Aralkum dust activity occurs under thick cloud cover, limiting the possibility of it being observed by satellites.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6022747
    Description: https://global-surface-water.appspot.com/download
    Description: https://soilgrids.org/
    Description: https://search.earthdata.nasa.gov/search
    Description: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels
    Description: https://ads.atmosphere.copernicus.eu/cdsapp#!/dataset/cams-global-reanalysis-eac4
    Description: https://ladsweb.modaps.eosdis.nasa.gov/search/
    Description: https://aeronet.gsfc.nasa.gov/
    Description: https://worldview.earthdata.nasa.gov/
    Keywords: ddc:551.5 ; dust aerosol ; Aralkum ; Central Asia ; modeling
    Language: English
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    Comparing different machine‐learning techniques to date Nile Delta sediments based on portable X‐ray fluorescence data (2022)
    Details
    Publication Date: 2024-01-12
    Description: Geomorphology generally aims to describe and investigate the processes that lead to the formation of landscapes, while geochronology is needed to detect their timing and duration. Due to restrictions on exporting geological samples from Egypt, modern geoscientific studies in the Nile Delta lack the possibility of dating the investigated sediments and geological features by standard techniques such as OSL or AMS 〈sup〉14〈/sup〉C; therefore, this study aims to validate a new approach using machine‐learning algorithms on portable X‐ray fluorescence (pXRF) data. Archaeologically dated sediments from the archaeological excavations of Buto (Tell el‐Fara'in; on‐site) that pXRF analyses have geochemically characterized serve as training data for running and comparing Neural Nets, Random Forests, and single‐decision trees. The established pXRF fingerprints are transferred via machine‐learning algorithms to set up a chronology for undated sediments from sediment cores (i.e., the test data) of the nearby surroundings (off‐site). Neural Nets and Random Forests work fine in dating sediments and deliver the best classification results compared with single‐decision trees, which struggle with outliers and tend to overfit the training data. Furthermore, Random Forests can be modeled faster and are easier to understand than the complex, less transparent Neural Nets. Therefore, Random Forests provide the best algorithm for studies like this. Furthermore, river features east of Kom el‐Gir are dated to pre‐Ptolemaic times (before 332 B.C.) when Kom el‐Gir had possibly not yet been settled. The research in this paper shows the success of close interactions from various scientific disciplines (Geoinformatics, Physical Geography, Archaeology, Ancient History) to decipher landscape evolution in the long‐term‐settled Nile Delta's environs using machine learning. With the approach's design and the possibility of integrating many other geographical/sedimentological methods, this study demonstrates the potential of the methodological approach to be applied in other geoscientific fields.
    Keywords: ddc:551.701 ; dating approach ; Egypt ; Neural Nets ; pattern recognition ; Random Forest
    Language: English
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    Properties of Turbulent Alfvénic Fluctuations and Wave‐Particle Interaction Associated With Io's Footprint Tail (2022)
    Details
    Publication Date: 2024-01-12
    Description: We investigate the small‐scale magnetic field fluctuations and their associated turbulent nature in the Io flux tube (IFT) connected to Io's footprint tail (IFPT). Our study is based on the recent magnetic field measurements by the Juno spacecraft during the PJ12 Juno flyby. Here, we are interested in understanding what type of turbulence is consistent with the fluctuations in the quasi‐dispersionless frequency range of 0.2–800 Hz as observed by Sulaiman et al. (2020), https://doi.org/10.1029/2020GL088432. Knowledge of the turbulent fluctuations is important to constrain the acceleration mechanisms for ions and electrons in the IFT. In this work, we suggest that the observed temporal fluctuations in the spacecraft frame correspond to Doppler‐shifted spatial fluctuation structured perpendicular to the background magnetic field. This would imply an alternative reinterpretation of the spectral index of the observed magnetic power spectral density to be potentially the result of weak‐MHD and sub‐ion scale kinetic Alfvén wave turbulence in the low‐frequency regime. Our theoretical modelings show that turbulence can be driven both in the torus region and at high‐latitudes rendering results in agreement with the Juno measurements. Calculated turbulence heating rates are consistent with observed energy fluxes in the IFT and represent efficient drivers for particle acceleration. Moreover, a widening of the IFPT structure with respect to the IFT extent is consistent with propagating dispersive Alfvén waves modified by kinetic effects on their group velocities.
    Description: Key Points: Low‐frequency Juno observations in the Io flux tube (IFT) tail represent structures perpendicular to background magnetic field. Magnetic field fluctuations observed in the Io footprint tail (IFPT) are consistent with weak‐MHD and sub‐ion kinetic Alfvén wave turbulence. Dispersion effects on group velocity of Alfvén waves widens the IFT consistent with the observed width of the IFPT.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.17189/1519711
    Description: https://doi.org/10.17189/1522461
    Keywords: ddc:523 ; Io ; Juno observations ; Alfvén waves ; magnetic field fluctuations
    Language: English
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    Understanding summer wind systems over the eastern Mediterranean in a high‐resolution climate simulation (2022)
    Latt, Melissa R. ; Hochman, Assaf ; Caldas‐Alvarez, Alberto ; [et al.]
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2024-01-12
    Description: Regional and local wind systems are often complex, particularly near coastal areas with a highly variable orography. Thus, the realistic representation of regional wind systems in weather and climate models is of strong relevance. Here, we evaluate the ability of a 13‐year convection‐permitting climate simulation in reproducing the interaction of several regional summer wind systems over the complex orography in the eastern Mediterranean region. The COSMO‐CLM simulations are driven by hourly ERA‐5 reanalysis and have a spatial resolution of 2.8 and 7.0 km. The simulated near‐surface wind fields are compared with unique very high‐resolution wind observations collected within the “Dead Sea Research Venue” project (DESERVE) and data from the Israel Meteorological Service synop network. The high‐resolution COSMO‐CLM simulations largely reproduce the main characteristics of the regional wind systems (Mediterranean and Dead Sea breeze, slope winds in the Judean Mountains and winds along the Jordan Rift valley), whereas ERA‐5 is only able to represent the Mediterranean Sea breeze. The high‐resolution simulations substantially improve the representation of regional winds, particularly over complex orography. Indeed, the 2.8 km simulation outperforms the 7.0 km run, on 88% of the days. Two mid‐July 2015 case studies show that only the 2.8 simulation can realistically simulate the penetration of the Mediterranean Sea Breeze into the Jordan Rift valley and complex interactions with other wind systems like the Dead Sea breeze. Our results may have profound implications for regional weather and climate prediction since very high‐resolution information seems to be necessary to reproduce the main summertime climatic features in this region. We envisage that such simulations may also be required at other regions with complex orography.
    Description: In this paper we show that COSMO‐CLM regional climate model simulations at 7.0 (CLM‐7.0) and 2.8km (CLM‐2.8) resolution can realistically reproduce near‐surface regional and local wind systems over the complex orography of the eastern Mediterranean as opposite to coarser resolutions (ERA‐5, 31 km). The Mediterranean and local Dead Sea breezes, slope winds over the Judean Mountains, and winds along the Jordan Rift valley are well represented both climatologically and on individual days. CLM‐2.8 captures the small‐scale variability of the wind field better than CLM‐7.0 particularly near the Dead Sea and on 88% of the days CLM‐2.8 represents wind speed even more realistically than CLM‐7.0. image
    Description: German Helmholtz Association (“Changing Earth” program)
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: Ministry of Science, Research and Arts
    Description: Helmholtz Association of German Research Centers
    Keywords: ddc:551.6 ; complex orography ; convection permitting ; COSMO‐CLM ; Dead Sea ; eastern Mediterranean ; grid spacing ; regional climate modelling ; sea breeze
    Language: English
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    Impact of Tropospheric Ties on UT1‐UTC in GNSS and VLBI Integrated Solution of Intensive Sessions (2022)
    Details
    Publication Date: 2024-01-12
    Description: Very Long Baseline Interferometry (VLBI) intensive (INT) sessions are critical for the rapid determination and densification of Universal Time 1‐Coordinate Universal Time (UT1‐UTC), which plays an important role in satellite geodesy and space exploration missions and is not predictable over longer time scales. Due to the limited observation geometry of INT sessions with two to three stations observing about 1 hr, tropospheric gradients cannot be estimated, which degrades the UT1‐UTC precision. We investigate the impact of tropospheric ties at Global Navigation Satellite Systems (GNSSs) and VLBI co‐located stations in INT sessions from 2001 to 2021. VLBI and GNSS observations are combined on the observation level. The results are evaluated by using both UT1‐UTC and Length of Day (LOD) from consecutive sessions. We demonstrate a better agreement of 10%–30% when comparing the derived LOD to GNSS LOD for INT1, INT2, and VGOS‐2 sessions; whereas, the agreement is not improved when directly comparing UT1‐UTC to the IERS Earth Orientation Parameters (EOPs) product, potentially because INT sessions also contribute to IERS EOP products. The major impact comes from tropospheric gradient ties, whereas applying zenith delay ties does not improve or even deteriorate UT1‐UTC agreement. Gradient ties also introduce systematic biases in UT1‐UTC by around −3 to −5 μs, except for the Russian INT sessions. Regression analysis shows that the east gradient introduces systematic effects in UT1‐UTC for sessions involving Germany and USA (Hawaii), whereas for Germany–Japan and Russian sessions, the north gradient also contributes systematically.
    Description: Plain Language Summary: Universal Time 1‐Coordinate Universal Time (UT1‐UTC) gives the time difference of UT1, defined by Earth's rotation, and UTC, defined by atomic clocks. UT1‐UTC is essential for real‐time navigation and space exploration. The variation of the first‐order negative time derivative of UT1‐UTC, Length of Day (LOD), is induced by mass redistribution, including tides of the solid Earth and oceans, the liquid core of the Earth and atmospheric variation, and climate events such as El Niño. Very Long Baseline Interferometry (VLBI) observing active galactic nuclei is the only space geodetic technique that can determine UT1‐UTC unambiguously. The 1‐hr intensive (INT) sessions, designed for the rapid determination and densification of UT1‐UTC, are performed daily with two VLBI radio telescopes. Due to the limited observation geometry, tropospheric gradients cannot be modeled in INT sessions, deteriorating UT1‐UTC estimates. We demonstrate an improvement of 10%–30% in LOD by applying tropospheric ties at VLBI and Global Navigation Satellite Systems co‐locations, especially the tropospheric gradients ties. Tropospheric gradient ties also introduce a systematic effect of −3 to −5 μs on UT1‐UTC, especially the east gradient. Our study shows that tropospheric ties should be adopted in future VLBI analysis for optimal UT1‐UTC products.
    Description: Key Points: Tropospheric ties are applied in a Global Navigation Satellite System–Very Long Baseline Interferometry (GNSS–VLBI) integrated solution analyzing VLBI intensive (INT) sessions from 2001 to 2021. Length of Day (LOD) of IVS INT sessions shows a better agreement by 10%–30% when compared to GNSS LOD product, mainly due to gradient ties. Gradient ties, especially the east one, introduce systematic biases of −3 to −5 μs in Universal Time 1‐Coordinate Universal Time of IVS INT sessions.
    Description: Helmholtz OCPC Program
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://www.iers.org/IERS/EN/DataProducts/EarthOrientationData/eop.html
    Description: http://doi.org/10.17616/R3RD2H
    Keywords: ddc:526 ; intensive sessions ; UT1‐UTC ; tropospheric ties ; GNSS ; VLBI ; integrated processing
    Language: English
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    Episodic Venting of a Submarine Gas Seep on Geological Time Scales: Formosa Ridge, Northern South China Sea (2022)
    Details
    Publication Date: 2024-01-12
    Description: The Formosa Ridge cold seep is among the first documented active seeps on the northern South China Sea passive margin slope. Although this system has been the focus of scientific studies for decades, the geological factors controlling gas release are not well understood due to a lack of constraints of the subsurface structure and seepage history. Here, we use high‐resolution 3D seismic data to image stratigraphic and structural relationships associated with fluid expulsion, which provide spatio‐temporal constraints on the gas hydrate system at depth and methane seepage at modern and paleo seafloors. Gas has accumulated beneath the base of gas hydrate stability to a critical thickness, causing hydraulic fracturing, propagation of a vertical gas conduit, and morphological features (mounds) at paleo‐seafloor horizons. These mounds record multiple distinct gas migration episodes between 300,000 and 127,000 years ago, separated by periods of dormancy. Episodic seepage still seems to occur at the present day, as evidenced by two separate fronts of ascending gas imaged within the conduit. We propose that episodic seepage is associated with enhanced seafloor sedimentation. The increasing overburden leads to an increase in effective horizontal stress that exceeds the gas pressure at the top of the gas reservoir. As a result, the conduit closes off until the gas reservoir is replenished to a new (greater) critical thickness to reopen hydraulic fractures. Our results provide intricate detail of long‐term methane flux through sub‐seabed seep systems, which is important for assessing its impact on seafloor and ocean biogeochemistry.
    Description: Plain Language Summary: Gas hydrates are ice‐like compounds that form in marine sediments. They can reduce the permeability of the sediments by clogging up the pore spaces, and influence how methane gas flows through sediments and then seeps out of the seafloor. Seepage of methane into the water column plays an important role in seafloor biology and ocean chemistry. In this study, we use 3D seismic imaging to investigate the subseafloor sediments of a ridge in the South China Sea where gas is currently seeping into the ocean. Our data show, in high detail, how gas migrates upward through the sediments due to the buoyancy of gas. Our data also reveal mound structures at certain depths beneath the seafloor. We interpret that these mounds represent distinct phases in the geological past where gas was seeping out of the seafloor. This indicates that gas seepage at this ridge has switched on and off (episodically) throughout geological time. We speculate that the episodic seepage is associated with rapid seafloor sedimentation, which changes pressure conditions beneath the seafloor. Our work improves the understanding of how gas seepage processes can change on geological timescales.
    Description: Key Points: Gas has accumulated beneath the base of gas hydrate stability, causing vertical gas conduit formation and seabed mounds. Mounds imaged within the conduit record episodic seepage between 300 and 127 kyrs ago. Quiescence may be associated with enhanced seafloor sedimentation that increases effective stress at the top of the gas reservoir.
    Description: MOST
    Description: ESAS
    Description: TEC
    Description: https://doi.pangaea.de/10.1594/PANGAEA.913192
    Keywords: ddc:553.1 ; gas hydrate ; gas conduit ; hydraulic fracturing ; episodic venting ; sedimentary processes ; offshore Taiwan
    Language: English
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    Bergrecht von Iglau B (2022)
    Details
    Publication Date: 2023-02-28
    Description: Bergrecht von Iglau, bestätigt von König Wenzel II. von Böhmen und Markgraf von Mähren im letzten Viertel des 13. Jahrhunderts. Niedergeschrieben im Anhang des Iglauer Stadtrechtes. Erweiterung und Präzisierung der im Iglauer Bergrecht A niedergeschriebenen rechtlichen Regelungen für den Bergbau im Königreich Böhmen und der Markgrafschaft Mähren.
    Description: source
    Keywords: ddc:522 ; ddc:343.077 ; König Wenzel II. von Böhmen ; Thomas Altemberger ; Böhmen ; Mähren ; Iglau/Jihlava ; Hermannstadt/Sibiu ; Silberbergbau ; Bergrecht
    Language: German , Latin
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    Entwurf einer Bergordnung des Kurfürsten Friedrich und der Herzöge Johann und Georg von Sachsen für den Schneeberg (2022)
    Details
    Publication Date: 2023-02-28
    Description: Entwurf der Bergordnung für den Schneeberg von Kurfürst Friedrich und den Herzögen Johann und Georg von Sachsen um 1490. Mit den in 9 Paragraphen gefassten Regelungen wird versucht den Bergbau auf den Schneeberg mit Subventionen, Erlass oder Senkung des Zehnten, Erstattung der Hüttenkost und Prämierung des Auffindens neuer Silbererzgänge, den Bergbau neuen Schwung zu verleihen. Diese von den Räten aufgesetzte Bergordnung wurde aber von den Landesherren abgelehnt. Auch ohne die Zustimmung der Landesherren wurde die Ordnung von den Räten in Kraft gesetzt.
    Description: source
    Keywords: ddc:343.077 ; ddc:622 ; Kurfürst Friedrich ; Herzog Johannes ; Herzog Georg ; Schneeberg ; Silberbergbau ; Sachsen ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
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    Bergordnung Kurfürst August für Schwarzenberg und Eibenstock (2022)
    Details
    Publication Date: 2023-02-28
    Description: Nach der Niederlage im Schmalkaldischen Krieg 1547, mußte Kurfürst Johann Friedrich I. von Sachsen Teile der Herrschaft Schwarzenberg an den neuen Kurfürst, Moritz von Sachsen, abtreten. Bedingt durch weitere kriegerische Auseinandersetzungen unterblieb die Erneuerung der Bergordnung für Schwarzenberg und Eibenstock von 1534 durch Kurfürst Moritz von Sachsen. Erst sein Nachfolger Kurfürst August von Sachsen erließ 1556 eine erneuerte Bergordnung. Grundlage bildete die alte Bergordnung von Schwarzenberg und Eibenstock vom 15. März 1534. Unter Hinzufügung von sechs weiteren Artikeln wurde die revidierte Bergordnung für Schwarzenberg und Eibenstock am 7. Februar 1556 erlassen.
    Description: source
    Keywords: ddc:622 ; ddc:343.077 ; Kurfürst Johann Friedrich I. von Sachsen ; Kurfürst Moritz von Sachsen ; Kurfürst August von Sachsen ; Eibenstock ; Schwarzenberg ; Zinnbergbau ; Kupferbergbau ; Wismutbergbau ; Bleibergbau ; Eisensteinbergbau ; Sachsen ; Bergordnung
    Language: German
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    Bergordnung Kurfürst Johann Friedrich I. für Eibenstock und die schwarzenbergischen Wälder (2022)
    Details
    Publication Date: 2023-02-28
    Description: Bergordnung für den Zinnbergbau in Eibenstock und den schwarzenbergischen Wäldern vom 15. März 1534. Nachdem Kurfürst Johann Friedrich I. von Sachsen die Herrschaft Schwarzenberg 1533 gekauft hatte, erließ er diese neue Ordnung für den Bergbau auf Zinn, aber auch auf Wismut, Eisenstein, Blei und Kupfer. In den 31 Artikeln wurden die Regelungen zum Betrieb der Gruben, den Rechten und Pflichten der Bergbeamten sowie der Bergleute niedergeschriebenen. Weiterhin wurde das Recht auf freies Holz für alle Belange des Bergbaus, die Pflicht zur wöchentlichen Zahlung des Büchsenpfennigs sowie die rechtlichen Bedingungen für das Seifenwerk und den Betrieb der Erzmühlen und Schmelzhütten genannt.
    Description: source
    Keywords: ddc:622 ; ddc:343.077 ; Kurfürst Johann Friedrich I. von Sachsen ; Albrecht von Tettau ; Christoph von Tettau ; Georg von Tettau ; Eibenstock ; Schwarzenberg ; Schneeberg ; Annaberg ; Zinnbergbau ; Kupferbergbau ; Wismutbergbau ; Bleibergbau ; Eisensteinbergbau ; Sachsen ; Bergordnung
    Language: German
    Type: doc-type:book , updatedVersion
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    3D Classified GPR Facies Models From Multi-Frequency Data Volumes: A Synthetic Study (2022)
    Details
    Publication Date: 2023-03-21
    Description: Modern GPR systems allow for acquiring densely sampled data sets also using different antenna frequencies. Here, we consider such a multi-frequency approach to image near-surface sedimentary structures at different spatial scales. Despite the steady technical development of GPR data acquisition, today’s interpretation techniques largely rely on single-frequency data sets typically interpreted in a manual and, thus, subjective and non-reproducible manner. To pave the way toward a more objective and reproducible interpretation of multi-frequency GPR data sets, we develop an attribute-based multi-scale workflow. We evaluate our flow by integrating information of synthetic 50 and 200 MHz GPR volumes modeled across complex sedimentary structures showing heterogeneities at multiple spatial scales. Our strategy results in a multi-scale facies model comprising major structural variations as characterized by the 50 MHz volume and structural details as resolved by the 200 MHz data. We conclude that this attribute-based workflow poses an efficient and reliable tool to interpret both single- and multi-frequency GPR data and, thus, can either be an alternative or a guide for typical manual interpretation approaches.
    Description: DFG
    Description: poster
    Language: English
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    Bias correction of daily precipitation for ungauged locations using geostatistical approaches: A case study for the CORDEX‐Africa ensemble (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-14
    Description: Climate model simulations typically exhibit a bias, which can be corrected using statistical approaches. In this study, a geostatistical approach for bias correction of daily precipitation at ungauged locations is presented. The method utilizes a double quantile mapping with dry day correction for future periods. The transfer function of the bias correction for the ungauged locations is established using distribution functions estimated by ordinary kriging with anisotropic variograms. The methodology was applied to the daily precipitation simulations of the entire CORDEX‐Africa ensemble for a study region located in the West African Sudanian Savanna. This ensemble consists of 23 regional climate models (RCM) that were run for three different future scenarios (RCP 2.6, RCP 4.5, and RCP 8.5). The evaluation of the approach for a historical 50‐year period (1950–2005) showed that the method can reduce the inherent strong precipitation bias of RCM simulations, thereby reproducing the main climatological features of the observed data. Moreover, the bias correction technique preserves the climate change signal of the uncorrected RCM simulations. However, the ensemble spread is increased due to an overestimation of the rainfall probability of uncorrected RCM simulations. The application of the bias correction method to the future period (2006–2100) revealed that annual precipitation increases for most models in the near (2020–2049) and far future (2070–2099) with a mean increase of up to 165mm⋅a−1 (18%). An analysis of the monthly and daily time series showed a slightly delayed onset and intensification of the rainy season.
    Description: Adapting water management strategies to future precipitation projected by climate models is associated with high uncertainty in sparsely gauged catchments. Kriging was utilized to estimate distribution parameters for ungauged locations in a West African region to perform a bias correction of the CORDEX‐Africa ensemble. The application of the bias correction method revealed higher annual precipitation amounts and an intensifaction of the rainy season but only little change to the onset of the rainy season.
    Description: German Federal Ministry of Education and Research, Bonn (BMBF), West African Science Service Centre on Climate Change and Adapted Land Use (WASCAL)
    Keywords: ddc:551.6 ; bias correction ; climate change ; CORDEX‐Africa ; geostatistical approaches ; precipitation ; quantile mapping ; West Africa
    Language: English
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    Non‐ and sub‐state climate action after Paris: From a facilitative regime to a contested governance landscape (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-14
    Description: The Paris Agreement marks a significant milestone in international climate politics. With its adoption, Parties call for non‐ and sub‐state actors to contribute to the global climate agenda and close the emissions gap left by states. Such a facilitative setting embraces non‐state climate action through joint efforts, synergies, and different modes of collaboration. At the same time, non‐state actors have always played a critical and confrontational role in international climate governance. Based on a systematic literature review, we identify and critically assess the role of non‐state climate action in a facilitative post‐Paris climate governance regime. We thereby highlight three constitutive themes, namely different state‐non‐state relations, competing level of ambition, and a variety of knowledge foundations. We substantiate these themes, derived from an inductive analysis of existing literature, with illustrative examples and propose three paradigmatic non‐state actor roles in post‐Paris climate governance on a continuum between compliance and critique. We thereby highlight four particular threats of a facilitative setting, namely substitution of state action, co‐optation, tokenism, and depoliticization. Future research should not limit itself to an effective integration of NSSAs into a facilitative climate regime, but also engage with the merits of contestation. This article is categorized under: Policy and Governance 〉 Multilevel and Transnational Climate Change Governance
    Description: Three constitutive themes—different state‐non‐state relations, levels of ambition, and knowledge foundations—define the multiple roles non‐ and sub‐state actors can occupy in the post‐Paris climate governance regime. Yet, calls for voluntary, collaborative, and synergetic non‐state climate action in a facilitative post‐Paris climate governance setting run the risk to overshadow fundamental tensions when governing climate change.
    Description: Svenska Forskningsrådet Formas http://dx.doi.org/10.13039/501100001862
    Description: Deutsche Forschungsgemeinschaft (DFG)
    Keywords: ddc:341.7 ; climate change governance ; contestation ; environmental politics ; non‐state actors ; Paris Agreement ; transformation
    Language: English
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    Investment traps and resilience to shocks: An experimental study of Central Asian collective water governance (2022)
    Details
    Publication Date: 2023-01-14
    Description: We theoretically and empirically investigate the investments of water users in a stylized local irrigation system. We model irrigation self‐management as an interdependent interaction of users in an evolutionary game and study the resilience of the irrigation system. The theoretical model implies multiple stable equilibria at different efficiency levels. Users may be trapped in a low level of collective investment or succeed by being locked in a high collective investment level, implying an irrigation system resilient against external shocks. The study seeks to empirically identify such lock‐ins in experimental interactions among Central Asian farmers. Furthermore, we inquire into whether a pre‐play cheap talk opportunity with peer‐monitoring or sanctioning treatments influence the self‐reinforcing dynamic. Our findings revealed several stable states. Among these states, there are both low and high levels of efficiency, which we measure in the size of public good. Communication among users results in higher collective investment levels. However, this does not guarantee the complete elimination of inferior conventions from best‐response play. Penalties crowded out the intrinsic motivation to cooperate as they reduced collective investment in both low‐ and high‐level equilibria. Our findings imply that institutional settings tailored to each community can improve resilience to climate‐driven perturbations in water resources.
    Description: VolkswagenStiftung (Volkswagen Foundation) http://dx.doi.org/10.13039/501100001663
    Description: Federal Ministry for Economic Cooperation (BMZ) http://dx.doi.org/10.13039/501100001663
    Keywords: ddc:333.91 ; Central Asia ; experiment ; multiple equilibria ; resilience ; water management ; Asie centrale ; expérimentation ; équilibres multiples ; résilience ; gestion de l'eau
    Language: English
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    Developing a Laser Induced Liquid Beam Ion Desorption Spectral Database as Reference for Spaceborne Mass Spectrometers (2022)
    Details
    Publication Date: 2023-01-14
    Description: Spaceborne impact ionization mass spectrometers, such as the Cosmic Dust Analyzer on board the past Cassini spacecraft or the SUrface Dust Analyzer being built for NASA's upcoming Europa Clipper mission, are of crucial importance for the exploration of icy moons in the Solar System, such as Saturn's moon Enceladus or Jupiter's moon Europa. For the interpretation of data produced by these instruments, analogue experiments on Earth are essential. To date, thousands of laboratory mass spectra have been recorded with an analogue experiment for impact ionization mass spectrometers. Simulation of mass spectra of ice grains in space is achieved by a Laser Induced Liquid Beam Ion Desorption (LILBID) approach. The desorbed cations or anions are analyzed in a time‐of‐flight mass spectrometer. The amount of unstructured raw data is increasingly challenging to sort, process, interpret and compare with data from space. Thus far this has been achieved manually for individual mass spectra because no database containing the recorded reference spectra was available. Here we describe the development of a comprehensive, extendable database containing cation and anion mass spectra from the laboratory LILBID facility. The database is based on a Relational Database Management System with a web server interface and enables filtering of the laboratory data using a wide range of parameters. The mass spectra can be compared not only with data from past and future space missions but also mass spectral data generated by other, terrestrial, techniques. The validated and approved subset of the database is available for general public (https://lilbid-db.planet.fu-berlin.de).
    Description: Plain Language Summary: Thousands of laboratory mass spectra, each with an individual set of experimental parameters, have been recorded so far using a facility situated at Freie Universität Berlin, Germany. The mass spectra help analyze and interpret data returned from spacecraft in the vicinity of icy moons in the Solar System. The unstructured laboratory data is increasingly challenging to sort and compare to the data from space. We developed an extendable database containing the laboratory data. The database is available for general public and allows filtering the stored data for a wide range of experimental parameters and, in turn, significantly improves analysis of data not only from past space missions but also future missions in particular.
    Description: Key Points: We describe the development of a comprehensive spectral database containing laboratory analogue data for spaceborne mass spectrometers. The database is based on a Relational Database Management System with a web interface and accessible for community use. Filtering the laboratory data using a wide range of experimental parameters allows a straightforward analysis of returned flight data.
    Description: EC, Horizon 2020 Framework Programme (H2020) http://dx.doi.org/10.13039/100010661
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5281/zenodo.6863855
    Description: https://sbnarchive.psi.edu/pds3/cassini/cda/COCDA_0007.tar.gz
    Keywords: ddc:550 ; mass spectral database ; analogue experiments ; ice grains ; ocean worlds ; SUDA ; ENIA ; LILBID ; TOF‐MS
    Language: English
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    An Analytical Framework for Determining the Ecological Risks of Wastewater Discharges in River Networks Under Climate Change (2022)
    Details
    Publication Date: 2023-01-14
    Description: Over the last decades, treatment of domestic wastewater promoted by environmental regulations have reduced human health risks and improved water quality. However, ecological risks caused by effluents of wastewater treatment plants (WWTPs) discharged into rivers still persist. Moreover, the evolution of these ecological risks in the future is intimately related to effects of changing climate, especially regarding streamflow in receiving rivers. Here, we present an analytical and transferable framework for assessing the ecological risks posed by WWTP‐effluents at the catchment scale. The framework combines the size‐class k of WWTPs, which is a load‐proxy, with their outflows' location in river networks, represented by stream‐order ω. We identify ecological risks by using three proxy indicators: the urban discharge fraction and the local‐scale concentrations of each total phosphorous and ammonium‐nitrogen discharged from WWTPs. About 3,200 WWTPs over three large catchments (Rhine, Elbe, and Weser) in Central Europe were analyzed by incorporating simulated streamflow for the most extreme projected climate change scenario. We found that WWTPs causing ecological risks in the future prevail in lower ω, across almost all k. Distinct patterns of ecological risks are identified in the k‐ω framework for different indicators and catchments. We show, as climate changes, intensified risks are especially expected in lower ω receiving effluents of intermediate‐k WWTPs. We discuss the implications of our findings for prioritizing WWTPs upgrading and urging updates on environmental regulations. Further discussions underline the feasibility of applying the framework to any geographical regions and highlight its potentials to help in achieving global long‐term commitments on freshwater security.
    Description: Key Points: An analytical, generic framework was developed to assess wastewater treatment plants causing ecological risks in rivers under climate change. Smaller streams will face higher ecological risks for almost all load classes of wastewater treatment plants in future climate. Of the legally regulated effluent parameters for treated wastewater, ammonium‐nitrogen concentration will pose the greatest ecological risk.
    Description: Helmholtz Association http://dx.doi.org/10.13039/501100009318
    Keywords: ddc:551.48 ; analytical assessment framework ; wastewater treatment plants emissions ; river stream‐order ; dilution ; local‐scale nutrients concentrations
    Language: English
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    Horizontal Wavenumber Spectra of Vertical Vorticity and Horizontal Divergence of Mesoscale Dynamics in the Mesosphere and Lower Thermosphere Using Multistatic Specular Meteor Radar Observations (2022)
    Details
    Publication Date: 2023-01-14
    Description: Specular meteor radars (SMRs) have significantly contributed to the understanding of wind dynamics in the mesosphere and lower thermosphere (MLT). We present a method to estimate horizontal correlations of vertical vorticity (Qzz) and horizontal divergence (P) in the MLT, using line‐of‐sight multistatic SMRs velocities, that consists of three steps. First, we estimate 2D, zonal, and meridional correlation functions of wind fluctuations (with periods less than 4 hr and vertical wavelengths smaller than 4 km) using the wind field correlation function inversion (WCFI) technique. Then, the WCFI's statistical estimates are converted into longitudinal and transverse components. The conversion relation is obtained by considering the rotation about the vertical direction of two velocity vectors, from an east‐north‐up system to a meteor‐pair‐dependent cylindrical system. Finally, following a procedure previously applied in the upper troposphere and lower stratosphere to airborne wind measurements, the longitudinal and transverse spatial correlations are fitted, from which Qzz, P, and their spectra are directly estimated. The method is applied to a special Spread spectrum Interferometric Multistatic meteor radar Observing Network data set, obtained over northern Germany for seven days in November 2018. The results show that in a quasi‐axisymmetric scenario, P was more than five times larger than Qzz for the horizontal wavelengths range given by ∼50–400 km, indicating a predominance of internal gravity waves over vortical modes of motion as a possible explanation for the MLT mesoscale dynamics during this campaign.
    Description: Key Points: We investigate the horizontal correlation functions of vertical vorticity and horizontal divergence for mesoscale wind fluctuations in the mesosphere and lower thermosphere. 2D zonal and meridional correlation functions and 1D longitudinal and transverse correlation functions as a function of horizontal lags are analyzed. The divergence dominated over the vorticity during November 2018 in northern Germany.
    Description: Leibniz SAW
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: French Ministry of Foreign and European
    Description: https://doi.org/10.22000/536
    Keywords: ddc:551.5 ; MLT ; vorticity ; correlation function ; meteor radar ; mesoscales ; divergence
    Language: English
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    High‐Resolution Aircraft Observations of Turbulence and Waves in the Free Atmosphere and Comparison With Global Model Predictions (2022)
    Details
    Publication Date: 2023-01-14
    Description: High‐resolution flight data obtained from in situ measurements in the free atmosphere aboard the High Altitude and Long Range Research Aircraft (HALO) are used to determine eddy dissipation rates along extended flights during the recent Southern Hemisphere Transport, Dynamics, and Chemistry aircraft campaign (SOUTHTRAC) in the 2019 austral winter. These data are analyzed and correlated with quantities characterizing the ambient airflow and the magnitudes of vertical energy propagation through internal gravity waves. The observed turbulence events are strongly correlated with elevated shear values, and overturning gravity waves do not appear to play a role. A highlight of the analysis is the validation of a recently implemented Clear Air Turbulence (CAT) forecast index in the European Centre for Medium‐Range Weather Forecast integrated forecast system. Here we find a slightly better correlation of the CAT prediction with the HALO research aircraft observations compared to those of commercial aircraft. The observed turbulence during SOUTHTRAC was never stronger than moderate, as EDR values remained below 0.3 m2/3 s−1. In general, light and light‐to‐moderate turbulence events were extremely rare, occurring in only about 5% of the flight time, and stronger events in less than 0.2%. These results are also reflected in the local atmospheric conditions, which were dominated by a thermally very stable airflow with low vertical shear and large Richardson numbers.
    Description: Plain Language Summary: This study analyzes high‐resolution data of velocity components in the upper troposphere and lower stratosphere collected with the German research aircraft High Altitude and Long Range Research Aircraft during the Southern Hemisphere Transport, Dynamics, and Chemistry (SOUTHTRAC) campaign in September–November 2019. Flights were conducted predominantly over the southern part of South America, the Drake Passage, and the Antarctic Peninsula. The objective of the analysis was to determine the eddy dissipation rates during the 22 flights. The cubic root of eddy dissipation rates is a common measure used to characterize turbulent regions in the atmosphere. High quality observations with a very accurately calibrated sensor are rare, especially in the remote areas of the SOUTHTRAC campaign. Observed eddy dissipation rates have been correlated with gravity wave activity, but these correlations are very small. A much stronger dependence of the eddy dissipation rates exists on the vertical shear of the horizontal wind. Thus, mechanical generation of turbulence appears to dominate in the observed cases. Overall, the observed turbulence was never stronger than moderate. Turbulence events were extremely rare, occurring in only about 5% of the flight time, and stronger events less than 0.2%. Finally, the observed eddy dissipation rates were compared with weather model forecasts, demonstrating their reliability in predicting turbulent regions.
    Description: Key Points: Small eddy dissipation rates were observed in the free atmosphere along extended research flights during Southern Hemisphere Transport, Dynamics, and Chemistry in austral winter 2019. Stronger turbulence events are rare and are mostly correlated with enhanced vertical shear of the horizontal wind. EDR predictions of a 15‐member ensemble shows higher correlation with research aircraft observations than with those by commercial aircraft.
    Description: Federal Ministry for Education and Research
    Description: German Science Foundation
    Description: https://halo-db.pa.op.dlr.de/mission/116
    Description: https://halo-db.pa.op.dlr.de/dataset/8497
    Description: https://halo-db.pa.op.dlr.de/dataset/8496
    Description: https://apps.ecmwf.int/codes/grib/param-db/?id=260290
    Description: https://doi.org/10.21957/xbar-5611
    Description: https://halo-db.pa.op.dlr.de/dataset/8955
    Description: https://madis.ncep.noaa.gov/acars_variable_list.shtml
    Keywords: ddc:551.5 ; turbulence in the free atmosphere ; eddy dissipation rate ; clear‐air turbulence predictions ; ECMWF integrated forecast system
    Language: English
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    Identifying Dominant Processes in Time and Space: Time‐Varying Spatial Sensitivity Analysis for a Grid‐Based Nitrate Model (2022)
    Details
    Publication Date: 2023-01-14
    Description: Distributed models have been increasingly applied at finer spatiotemporal resolution. However, most diagnostic analyses aggregate performance measures in space or time, which might bias subsequent inferences. Accordingly, this study explores an approach for quantifying the parameter sensitivity in a spatiotemporally explicit way. We applied the Morris method to screen key parameters within four different sampling spaces in a grid‐based model (mHM‐Nitrate) for NO3‐N simulation in a mixed landuse catchment using a 1‐year moving window for each grid. The results showed that an overly wide range of aquatic denitrification rates could mask the sensitivity of the other parameters, leading to their spatial patterns only related to the proximity to outlet. With adjusted parameter space, spatial sensitivity patterns were determined by NO3‐N inputs and hydrological transport capacity, while temporal dynamics were regulated by annual wetness conditions. The relative proportion of parameter sensitivity further indicated the shifts in dominant hydrological/NO3‐N processes between wet and dry years. By identifying not only which parameter(s) is(are) influential, but where and when such influences occur, spatial sensitivity analysis can help evaluate current model parameterization. Given the marked sensitivity in agricultural areas, we suggest that the current NO3‐N parameterization scheme (land use‐dependent) could be further disentangled in these regions (e.g., into croplands with different rotation strategies) but aggregated in non‐agricultural areas; while hydrological parameterization could be resolved into a finer level (from spatially constant to land use‐dependent especially in nutrient‐rich regions). The spatiotemporal sensitivity pattern also highlights NO3‐N transport within soil layers as a focus for future model development.
    Description: Key Points: A diagnostic analysis was conducted to disentangle the parameter sensitivity for NO3‐N simulations in catchment modeling in space and time. Sensitivity differed within sampling spaces, but was controlled spatially by NO3‐N supply/water fluxes while temporally by wetness condition. Analysis suggests finer‐level parameterization needs in arable land, and prioritizes NO3‐N transport in soils for improved conceptualization.
    Description: Chinese Scholarship Council
    Description: Leverhulme Trust http://dx.doi.org/10.13039/501100000275
    Description: Einstein Stiftung Berlin http://dx.doi.org/10.13039/501100006188
    Description: Berlin University Alliance http://dx.doi.org/10.13039/501100021727
    Description: https://doi.org/10.5281/zenodo.6497225
    Description: https://fred.igb-berlin.de/data/package/629
    Keywords: ddc:551 ; spatial time‐varying sensitivity analysis ; distributed nitrate modeling
    Language: English
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    Distribution, drivers and population structure of the invasive alien snail Tarebia granifera in the Luvuvhu system, South Africa (2022)
    Makherana, Fhatuwani ; Cuthbert, Ross N. ; Dondofema, Farai ; [et al.]
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-01-14
    Description: Invasive alien species continue to spread and proliferate in waterways worldwide, but environmental drivers of invasion dynamics lack assessment. Knowledge gaps are pervasive in the Global South, where the frequent heavy human‐modification of rivers provides high opportunity for invasion. In southern Africa, the spatio‐temporal ecology of a widespread and high‐impact invasive alien snail, Tarebia granifera, and its management status is understudied. Here, an ecological assessment was conducted at seven sites around Nandoni Reservoir on the Luvuvhu River in South Africa. The distribution and densities of T. granifera were mapped and the potential drivers of population structure were explored. T. granifera was widespread at sites impacted to varying extents due to anthropogenic activity, with densities exceeding 500 individuals per square meter at the most impacted areas. T. granifera predominantly preferred shallow and sandy environments, being significantly associated with sediment (i.e., chlorophyll‐a, Mn, SOC, SOM) and water (i.e., pH, conductivity, TDS) variables. T. granifera seemed to exhibit two recruitment peaks in November and March, identified via size‐based stock assessment. Sediment parameters (i.e., sediment organic matter, sediment organic carbon, manganese) and water chemistry (i.e., pH, total dissolved solids, conductivity) were found to be important in structuring T. granifera populations, with overall snail densities highest during the summer season. We provide important autecological information and insights on the distribution and extent of the spread of T. granifera. This may help in the development of invasive alien snail management action plans within the region, as well as modelling efforts to predict invasion patterns elsewhere based on environmental characteristics.
    Description: Alexander von Humboldt‐Stiftung http://dx.doi.org/10.13039/100005156
    Description: National Research Foundation http://dx.doi.org/10.13039/501100001321
    Description: University of Venda http://dx.doi.org/10.13039/501100008976
    Keywords: ddc:577.6 ; aquatic non‐native invasions ; environmental gradients ; Global South ; human‐modified river ; quilted melania ; reservoir
    Language: English
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    Spatio‐Temporal Level Variations of the Martian Seasonal North Polar Cap From Co‐Registration of MOLA Profiles (2022)
    Xiao, Haifeng ; Stark, Alexander ; Schmidt, Frédéric ; [et al.]
    Details
    Publication Date: 2023-01-14
    Description: The seasonal deposition and sublimation of CO2 constitute a major element in Martian volatile cycles. We reprocess the Mars Orbiter Laser Altimeter (MOLA) data and apply co‐registration procedures to obtain spatio‐temporal variations in levels of the Seasonal North Polar Cap (SNPC). The maximum level over the Residual North Polar Cap (RNPC) is 1.3 m, approximately half of that at the south pole (2.5 m). However, the maximum level in the dune fields at Olympia Undae can be up to 3.8 m. Furthermore, off‐season decreases up to 3 m during the northern winter at Olympia Undae are observed. These are likely due to metamorphism effects accentuated by the reduced snowfall at this period. Meanwhile, off‐season increases of up to 2 m during the northern spring are noted, the cause of which remains to be explored. The volume of the SNPC peaks at the end of northern winter and is estimated to be approximately 9.6 × 1012 m3, which is 2% more than that of the Seasonal South Polar Cap. The bulk density of the SNPC can go through phased decreases in accordance with phased accumulation at northern high‐latitudes. These findings can put important constraints on the Martian volatile cycling models.
    Description: Plain Language Summary: Due to its axial tilt, seasons also exist on Mars. Up to one third of the atmosphere's CO2 is in annual exchange with the polar regions through seasonal deposition/sublimation processes. Here, we make use of previously proposed approaches of analyzing the Mars Orbiter Laser Altimeter profiles and obtain spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC). Particularly, we bring attention to abnormal behavior of the SNPC in the dune fields at Olympia Undae. Maximum level there can be all the way up to 4 m which is much higher than a maximum of 1.5 m over the Residual North Polar Cap. Meanwhile, off‐season decreases during the northern winter with magnitudes up to 3 m and off‐season increases during the northern spring of magnitudes up to 2 m are observed. These could possibly be related to metamorphism of the seasonal deposits and phased snowfall. The maximum volume of the SNPC is constrained to be 9.6 × 1012 m3. The bulk density of the SNPC does not continuously increase as previously assumed but can go through phased decreases in accordance with phased snowfall at the north pole. These findings can put important constraints on the Martian climate models.
    Description: Key Points: Through co‐registration of laser altimetry profiles, spatio‐temporal level variations of the Seasonal North Polar Cap (SNPC) of Mars are obtained. Maximum level of the SNPC can be up to 3.8 m at Olympia Undae and up to 1.3 m over the Residual North Polar Cap. Northern winter decreases of up to 3 m and northern spring increases of up to 2 m are observed at Olympia Undae.
    Description: China Scholarship Council
    Description: Deutsche Forschungsgemeinschaft
    Description: Institut National des Sciences de l’Univers
    Description: Centre National de la Recherche Scientifique
    Description: Centre National d’Etudes Spatiales
    Description: https://doi.org/10.17632/x953mzxxvv.1
    Description: https://doi.org/10.17632/z59b9nd6s9.2
    Description: https://pds-geosciences.wustl.edu/missions/mgs/pedr.html
    Description: https://naif.jpl.nasa.gov/pub/naif/pds/data/mgs-m-spice-6-v1.0/mgsp_1000/data/
    Description: https://www.uahirise.org/hiwish/browse
    Keywords: ddc:523 ; Mars ; seasonal polar cap ; CO2 ice ; MOLA ; level variation ; pseudo cross‐over
    Language: English
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    Digitization of imaging plates from Guinier powder X‐ray diffraction cameras (2022)
    Nasir, Jamal ; Steinbrück, Nils ; Xu, Ke ; [et al.]
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-01-15
    Description: A Guinier camera equipped with an imaging plate is used to investigate and eliminate the sources of instrumental errors affecting the quality of the obtained scanned Guinier data. A program with a graphical user interface is presented which converts the data of the scanned images into different standard file formats for powder X‐ray patterns containing intensities, their standard deviations and the diffraction angles. The program also allows for manual and automatic correction of the 2gθ scale against a known reference material. It is shown using LaB6 that the exported X‐ray diffraction patterns provide a 2gθ scale reproducible enough to allow for averaging diffractograms obtained from different exposures of the imaging plate for the same sample. As shown on a mixture of NaCl and sodalite, the quality of the produced data is sufficient for Rietveld refinement. The software including source code is made available under a free software license.
    Description: A program for the digitization of Guinier powder diffraction images is described, which works with images from both optical and laser scanners. Thus, processing of data from storage‐phosphor‐based imaging plates and Ag‐based photographic films is possible.
    Keywords: ddc:548 ; IPreader software ; Guinier cameras ; imaging plates (IPs) ; diffraction pattern conversion into data columns ; powder X‐ray diffraction ; data processing ; Guinier method
    Language: English
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    Martian Atmospheric Spectral End‐Members Retrieval From ExoMars Thermal Infrared (TIRVIM) Data (2022)
    Details
    Publication Date: 2023-01-15
    Description: Key knowledge about planetary composition can be recovered from the study of thermal infrared spectral range datasets. This range has a huge diagnostic potential because it contains diagnostic absorptions from a planetary surface and atmosphere. The main goal of this study is to process and interpret the dataset from the Thermal Infrared channel (TIRVIM) which is part of the Atmospheric Chemistry Suite of the ExoMars2016 Trace Gas Orbiter mission to find and characterize dust and water ice clouds in the atmosphere. The method employed here is based on the application of principal component analysis and target transformation techniques to extract the independent variable components present in the analyzed dataset. Spectral shapes of both atmospheric dust and water ice aerosols have been recovered from the analysis of TIRVIM data. The comparison between our results with those previously obtained on Thermal Emission Spectrometer (TES) data and with previous analysis on TIRVIM data, validates the methodology here applied, showing that it allows to correctly recover the atmospheric spectral endmembers present in the TIRVIM data. Moreover, comparison with atmospheric retrievals on PFS, TES and IRIS data, allowed us to assess the temporal stability and homogeneity of dust and water ice components in the Martian atmosphere over a time period of almost 50 years.
    Description: Plain Language Summary: The analysis of thermal infrared datasets from planetary bodies is of key importance for the understanding of a planet's climate evolution and history: it contains valuable information about composition, temperature and state of the atmosphere. Moreover, surface properties and the surface‐atmosphere interaction can be studied. Here we investigated new thermal infrared data from the Thermal Infrared channel instrument of the ExoMars Trace Gas Orbiter with the main goal of carefully identifying Martian atmospheric dust and water ice clouds components. A methodology based on principal component and target transformation factor analysis techniques has been applied. Based on our results, this methodology can correctly recover both atmospheric dust and water ice aerosols spectral shapes and their abundances in the Martian atmosphere.
    Description: Key Points: First successful application of principal components and target transformation techniques to high‐resolution Thermal Infrared channel (TIRVIM) data. Spectral shapes of both atmospheric dust and water ice clouds are recognized and recovered. TIRVIM data are successfully modeled through a linear combination of the recovered water ice and dust end‐members.
    Description: Roscosmos and ESA
    Description: https://doi.org/10.5281/zenodo.7032738
    Keywords: ddc:523 ; Martian atmosphere ; TIRVIM data
    Language: English
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    Measuring zero water level in stream reaches: A comparison of an image‐based versus a conventional method (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-15
    Description: A limited number of gauging stations, especially for nested catchments, hampers a process understanding of the interaction between streamflow, groundwater and water usage during drought. Non‐commercial measurement devices can help overcome this lack of monitoring, but they need to be thoroughly tested. The Dreisam River in the South‐West of Germany was affected by several hydrological drought events from 2015 to 2020 during which parts of the main stream and tributaries fell dry. Therefore it provided a useful case study area for a flexible longitudinal water quality and quantity monitoring network. Among other measurements the setup employs an image‐based method with QR codes as fiducial marker. In order to assess under which conditions the QR‐code based water level loggers (WLL) deliver data according to scientific standards, we compared its performance to conventional capacitive based WLL. The results from 20 monitoring stations reveal that the riverbed was dry for 〉50% at several locations and even for 〉70% at most severely affected locations during July and August 2020, with the north western parts of the catchment being especially concerned. Highly variable longitudinal drying patterns of the stream reaches emerged from the monitoring. The image‐based method was found valuable for identification and validation of zero level occurrences. Nevertheless, a simple image processing approach (based on an automatic thresholding algorithm) did not compensate for errors due to natural conditions and technical setup. Our findings highlight that the complexity of measurement environments is a major challenge when working with image‐based methods.
    Description: We monitored zero water levels in a meso‐scale catchment with temperate climate by means of image‐based and conventional water level logging techniques. A detailed analysis of the longitudinal drying patterns enables a discussion about hydrological connectivity and the processes influencing the drying.
    Description: Badenova Fund For Innovation
    Description: https://doi.org/10.6094/UNIFR/228702
    Keywords: ddc:551.48 ; hydrological drought ; innovative sensors ; longitudinal connectivity ; stream reaches ; streamflow intermittency ; zero flow
    Language: English
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    Present‐Day Upper‐Mantle Architecture of the Alps: Insights From Data‐Driven Dynamic Modeling (2022)
    Details
    Publication Date: 2023-01-15
    Description: The dynamics of the Alps and surrounding regions is still not completely understood, partly because of a non‐unique interpretation of its upper‐mantle architecture. In particular, it is unclear if interpreted slabs are consistent with the observed surface deformation and topography. We derive three end‐member scenarios of lithospheric thickness and slab geometries by clustering available shear‐wave tomography models into a statistical ensemble. We use these scenarios as input for geodynamic simulations and compare modeled topography, surface velocities and mantle flow to observations. We found that a slab detached beneath the Alps, but attached beneath the Northern Apennines captures first‐order patterns in topography and vertical surface velocities and can provide a causative explanation for the observed seismicity.
    Description: Plain Language Summary: Present‐day surface deformation, including earthquakes, plate motion, and mass (re)distribution, results from processes operating at the surface and in the interior of the Earth. Understanding these processes and their coupling is of utmost importance in light of the hazard they pose to society. The Alps provide an excellent natural laboratory to understand such coupling. Here, we use seismic tomography models to constrain its upper‐mantle architecture. We further use these models to quantify forces originating from the resolved architecture and their effects on the present‐day surface deformation. The models can reproduce first‐order patterns in the observed topography and vertical surface motions. We found a causative correlation between the presence of a shallow slab attached to the overlying lithosphere in the Northern Apennines and the seismicity in the region. Our results allow us to better understand the transfer of internal forces to the surface, thereby helping to quantify the present‐day mechanical setup of the area.
    Description: Key Points: Statistical ensemble of S‐wave tomography models is used to infer the Lithosphere‐Asthenosphere Boundary configuration and slab geometries in the Alps. The 3‐D upper‐mantle architecture from the statistics reproduce first‐order patterns in observed topography and Global Navigation Satellite Systems vertical velocities. A shallow/attached slab in the Northern Apennines is consistent with the mantle depth seismicity observed in this region.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.5880/GFZ.4.5.2019.004
    Description: https://gfzpublic.gfz-potsdam.de/pubman/item/item_238001
    Description: http://ds.iris.edu/ds/products/emc-earthmodels/
    Description: https://doi.org/10.5281/zenodo.7071571
    Description: https://doi.org/10.5281/zenodo.6538257
    Keywords: ddc:551.1 ; Alps ; Apennines ; lithospheric architecture ; slabs ; seismicity
    Language: English
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    Cold‐water coral ecosystems under future ocean change: Live coral performance vs. framework dissolution and bioerosion (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-15
    Description: Physiological sensitivity of cold‐water corals to ocean change is far less understood than of tropical corals and very little is known about the impacts of ocean acidification and warming on degradative processes of dead coral framework. In a 13‐month laboratory experiment, we examined the interactive effects of gradually increasing temperature and pCO2 levels on survival, growth, and respiration of two prominent color morphotypes (colormorphs) of the framework‐forming cold‐water coral Lophelia pertusa, as well as bioerosion and dissolution of dead framework. Calcification rates tended to increase with warming, showing temperature optima at ~ 14°C (white colormorph) and 10–12°C (orange colormorph) and decreased with increasing pCO2. Net dissolution occurred at aragonite undersaturation (ΩAr 〈 1) at ~ 1000 μatm pCO2. Under combined warming and acidification, the negative effects of acidification on growth were initially mitigated, but at ~ 1600 μatm dissolution prevailed. Respiration rates increased with warming, more strongly in orange corals, while acidification slightly suppressed respiration. Calcification and respiration rates as well as polyp mortality were consistently higher in orange corals. Mortality increased considerably at 14–15°C in both colormorphs. Bioerosion/dissolution of dead framework was not affected by warming alone but was significantly enhanced by acidification. While live corals may cope with intermediate levels of elevated pCO2 and temperature, long‐term impacts beyond levels projected for the end of this century will likely lead to skeletal dissolution and increased mortality. Our findings further suggest that acidification causes accelerated degradation of dead framework even at aragonite saturated conditions, which will eventually compromise the structural integrity of cold‐water coral reefs.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Marine Research in Ireland
    Description: French National Research Agency http://dx.doi.org/10.13039/501100001665
    Keywords: ddc:577.7 ; cold-water corals ; ocean change ; laboratory experiments ; framwork dissolution ; bioerosion
    Language: English
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    Using InSAR Velocity Measurements at Transmission Towers to Calibrate Ground Motion Data (2022)
    Details
    Publication Date: 2023-03-15
    Description: poster
    Keywords: ddc:550 ; InSAR
    Language: English
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    Faktencheck – Vergleichende Betrachtung der Treibhausgasbilanz einer Sanierung von landwirtschaftlich genutzten Hochmoorböden (2022)
    Details
    Publication Date: 2023-05-30
    Description: Die nationale Moorschutzstrategie setzt eine Reduzierung der jährlichen Treibhausgas-Emissionen (THG) um 5 Millionen Tonnen von den organischen Böden Deutschlands zum Ziel. Aufgrund der Nutzungsverteilung muss der wesentliche Beitrag zur Erreichung dieses Zieles von den landwirtschaftlich genutzten Flächen kommen. Zur Vermeidung von hohen Methan-Emissionen und um eine möglichst geeignete Ausgangslage für die Vegetationsentwicklung in Richtung einer torfakkumulierenden Hochmoorvegetation zu schaffen, ist der Abtrag des landwirtschaftlichen Oberbodens mit Beginn der Maßnahme notwendig. Es ist anzunehmen, dass der abgetragene organische Boden in der Folge entweder im durchlüfteten Teil der Verwallungen, in die er eingebaut wird, oder in einer externen Nutzung in Erden und Substraten oxidieren und somit zu THG-Emissionen führen wird. Die aktuelle Diskussion um die Photovoltaik auf Freiflächen, die unter anderem die landwirtschaftlich genutzten Moorböden im Fokus hat, gibt dieser Betrachtung weiteres Gewicht, da die Vernässung der Moorflächen für diese Nutzung als Prämisse gesetzt wird. Auch für die Einrichtung des Sphagnum farmings, der Paludikultur auf Hochmoorstandorten, ist der Abtrag des landwirtschaftlichen Oberbodens notwendig. Die THG-Bilanz der Vernässung mit Hochmoorentwicklung mit Abtrag des landwirtschaftlichen Oberbodens (Hochmoorsanierung) wird in dieser Betrachtung einer Vernässung ohne Abtrag und der Ausgangslage gegenübergestellt. Dies soll zu einer Versachlichung der Diskussion des Themas durch die Bereitstellung von Grundlagendaten beitragen. Im Ergebnis zeigt sich, dass die Variante mit Oberbodenabtrag zu den geringsten THG-Emissionen führt. Die Varianten einer Vernässung mit und ohne Oberbodenabtrag liegen aber im Vergleich zur „Nullvariante“ relativ dicht beieinander, zumal die Unsicherheiten aufgrund fehlender Grundlagenforschung zur Dauer der Methan-Emissionen und der Oxidationsrate von Substraten noch erheblich sind. Allerdings führt die Variante mit Oberbodenabtrag kurzfristig zu einer potenziellen Hochmoor-Vegetationsentwicklung, insbesondere mit Torfmoos-Beimpfung. Dies ist ohne Abtrag mittel- bis langfristig nicht zu erwarten. Abschließend ist festzuhalten, dass die Vernässung in jedem Fall aus klimatischen Aspekten der Fortführung einer entwässerungsbasierten Landwirtschaft vorzuziehen ist.
    Description: The national peatland protection strategy sets a target of reducing annual greenhouse gas (GHG) emissions by 5 million tons from Germany’s organic soils. Due to the distribution of land use, the main contribution to achieving this goal must come from agriculturally used land. To avoid high methane emissions and to create the most appropriate conditions for vegetation development towards peat accumulating raised bog vegetation, the removal of the agricultural topsoil is necessary with the start of the measure. It can be assumed that the removed organic soil will subsequently oxidize either in the aerated part of the embankments in which it is constructed or in a use in soils and substrates, thus leading to GHG emissions. The current discussion about photovoltaics on agricultural used lands, which among other things focuses on organic soils, lends further weight to this consideration, since the rewetting is set as a pre-condition for this use. Removal of agricultural topsoil is also necessary for the establishment of Sphagnum farming, paludiculture on raised bog sites. In this review, the GHG balance of waterlogging with raised bog development with removal of agricultural topsoil (raised bog restoration) is compared to waterlogging without removal at the baseline. This is intended to help objectify the discussion of the topic by providing baseline data. The result shows that the variant with topsoil removal leads to the least GHG emissions. However, the variants of waterlogging with and without topsoil removal are relatively close to each other compared to the “no action” option, especially since the uncertainties are still considerable due to the lack of basic research on the duration of methane emissions and the oxidation rate of substrates. However, the variant with topsoil removal results in potential raised bog vegetation development in the short term, especially with peat moss inoculation. This is not expected to occur in the medium to long term without topsoil removal. In conclusion, from a climatic point of view, rewetting is in any case preferable to the continuation of drainage-based agriculture.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; Hochmoorsanierung ; Methanemission ; Oxidationsrate ; Sphagnum ; torfakkumulierende Vegetation ; Bog restoration ; methane emission ; oxidation rate ; peat-accumulating vegetation
    Language: German
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    Ausbringungsversuch von Bultmoosen in die wiedervernässten Torfabbauflächen im Naturschutzgebiet "Ahlen-Falkenberger Moor Halemer/Dahlemer See" (Niedersachsen) (2022)
    Details
    Publication Date: 2023-05-15
    Description: Im Naturschutzgebiet „Ahlen-Falkenberger Moor, Halemer/Dahlemer See“ wurde vor der Unterschutzstellung auf großen Flächen Torf abgebaut. Nach Beendigung des Abbaus wurden die Flächen gepoldert und durch Anstau von Niederschlagswasser wiedervernässt. Nach 10 bis 20 Jahren autogener Sukzession sind die Flächen hinsichtlich der Wiederbesiedlung mit Torfmoosen immer noch in einem Pionierstadium eines Torfmoos-Wollgras-Stadiums mit den dominanten Pionierarten Sphagnum fallax und S. cuspidatum. Eine Weiterentwicklung im Sinne einer Hochmoorregeneration mit Bult-Schlenken Komplexen ist nicht erkennbar. Da die Wiederbesiedlung möglicherweise dem Ausbleiben von generativer Reproduktion und an Verbreitungsbarrieren scheitert, wurden 2017 die Arten Sphagnum magellanicum, Sphagnum rubellum, Sphagnum papillosum und Polytrichum strictum auf dem Torfmoosfeld beim Moor-Informationszentrum (MoorIZ) Bultmoose geerntet und auf fünf Wiedervernässungsflächen ausgebracht. In den Versuchsflächen wurden die Moose als Fragmente in unterschiedlicher Dichte (75 und 100 %) eingebettet und als Soden (30 cm to 30 cm) aufgesetzt. Nach fünf Beobachtungsjahren wurde der Anwuchserfolg bewertet und Empfehlungen für die Ausbringung von Bultmoosen abgeleitet. Die besten Etablierungs- und Ausbreitungsergebnisse wurden mit verpflanzten Soden erzielt. Sie zeigen die höchste Resilienz gegenüber Wasserstands- und Witterungsschwankungen.
    Description: In the nature reserve “Ahlen-Falkenberger Moor, Halemer/Dahlemer See”, large areas were harvested for peat before they were under protection. After industrial peat mining, the areas were poldered and rewetted by impounding rainwater. Ten to 20 years later, the areas are still dominated by cotton grass and pioneer peat moss species, such as Sphagnum fallax and S. cuspidatum without the establishement of hummock peat mosses. Because spontaneous recolonization of hummock species may fail due to a lack of sexual reproduction or dispersal barriers, these species were reintroduced to rewetted sites in 2017. The species Sphagnum magellanicum, Sphagnum rubellum, Sphagnum papillosum und Polytrichum strictum were harvested from a nearby Sphagnum farming site and spread on five rewetted areas in 2017. In the plots the species have been introduced as fragments in different densities (covering 75 % and 100 %) and as sods (30 cm to 30 cm). The development of the plants was monitored and evaluated during a five-year-period to develop recommendations for the reintroduction of hummock peat moss species on rewetted bogs. The best establishment and propagation results were obtained by transplanting sods, which showed the highest resilience to water level and weather fluctuations.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; Torfmoose ; Hochmoorregeneration ; Ahlenmoor ; peat moss ; bog regeneration
    Language: German
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    Dr. Peter Steffens (2022)
    Details
    Publication Date: 2023-05-15
    Description: In memoriam Dr. Peter Steffens (25. Juni 1940 bis 15. Dezember 2021)
    Description: SUB Göttingen, DGMT
    Description: editorial
    Keywords: ddc:553.21 ; Nachruf ; obituary
    Language: German
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    Diskussion von Gesetzen zur Wasserleitfähigkeit in Torfböden (2022)
    Details
    Publication Date: 2023-05-15
    Description: Gezeigt wird, dass die üblichen Strömungsgesetze, basierend auf Druck- und Geschwindigkeitsgradienten nach Darcy und Hagen-Poiseuille, zur Beschreibung der Strömung von Wasser in Porensystemen von Torfböden physikalischen und mathematischen Grundsätzen nicht (bzw. nur sehr eingeschränkt) genügen. Deshalb wird das Fallgesetz nach Galilei und Newton als Strömungsgesetz, beruhend auf Energiehöhen und quadratischen Geschwindigkeiten, vorgeschlagen und diskutiert.
    Description: It is shown that the common laws of flow based upon gradients of pressure and velocity according to Darcy and Hagen-Poiseuille do not properly describe the real flow of water in pore systems of peat soils according to physical and mathematical principles. Instead, the law of fall of bodies by Galilei and Newton based upon the height of energy and quadratic velocities are discussed.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; Hagen-Poiseuille & Darcy vs. Galilei & Newton ; Wasserströmung nach Fallgesetz ; flow of water due to the law of fall
    Language: German
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    Prof. Dr. Klaus Dierßen (2022)
    Details
    Publication Date: 2023-05-15
    Description: In memoriam Prof. Dr. Klaus Dierßen (01. Juni 1948 bis 05. September 2022).
    Description: SUB Göttingen, DGMT
    Description: editorial
    Keywords: ddc:553.21 ; Nachruf ; obituary
    Language: German
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    Die C.A. Weber-Medaille für Gerfried Caspers – eine sehr persönliche Laudatio (2022)
    Details
    Publication Date: 2023-05-15
    Description: SUB Göttingen, DGMT
    Description: editorial
    Keywords: ddc:553.21 ; Laudatio
    Language: German
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    JÖRN KASCH – Ehrenmitglied der DGMT (2022)
    Details
    Publication Date: 2023-05-15
    Description: Laudatio anlässlich der Verleihung der Ehrenmitgliedschaft während der 27. Jahreshauptversammlung der DGMT am 3. Juni 2022 in Freiburg.
    Description: SUB Göttingen, DGMT
    Description: editorial
    Keywords: ddc:553.21 ; Laudatio
    Language: German
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    Das Schwarze Moor in der Rhön – Vergangenheit und Zukunft, Zustand und Handlungsbedarf für Deutschlands einziges Kermi-Hochmoor (2022)
    Details
    Publication Date: 2023-05-16
    Description: Das Schwarze Moor in der Rhön ist das einzige Kermihochmoor in Mitteleuropa. Die Kälteperiode im Mittelalter, nutzungsbedingte Entwaldung der Umgebung und extensive Beweidung des Hochplateaus und ein Bach an seiner Südgrenze, der die Ausbreitung des Moores stoppte, bedingten sein Höhenwachstum, das wiederum an den Flanken die Bildung von Kermistrukturen förderte. Das Moor liegt an der klimatischen Niederschlags-Grenze des Hochmoorwachstums. Bis um 1900 war das Moor weitgehend gehölzfrei, seither befindet es sich in einem Prozess zunehmender Kolonisierung mit Karpatenbirke und Waldkiefer. Seit 1924 werden von verschiedenen Autoren in unterschiedlichen Zeiten Ursachen diskutiert: Klimaschwankungen, globale Erwärmung mit verringerten Niederschlägen, Nährstoffeintrag, Wiederbewaldung des Randgehänges und nicht zuletzt Trockenlegung des Umfeldes und Ableitung der natürlichen Einspeisung in den Randlagg. Die Kombination der Einflüsse wirkt sich in den verschiedenen Teilräumen (Hydrotopen) unterschiedlich aus. Dies wird auf Grundlage der Vegetationskarte von Gies (1972) differenziert dargestellt. In der politisch aufgeheizten Diskussion um Gehölzentnahme zur „Rettung“ der offenen, wachsenden Moorweite wird übersehen, dass die Gehölze nur das auffälligste Ergebnis zunehmender Austrocknung des Moores sind, nicht die Ursache. Für Torfmooswachstum ist ein permanent hoher Wasserstand zwingend, die Torfmoose können nur dann die Zwergsträucher unterdrücken. Die Heide, Krähenbeere und Moorbeere sind Mykorrhizaträger und ihre Symbiosepilze können im sauerstoffarmen Moorwasser nicht existieren. Noch reichen die Niederschläge aus, um bestehende Wachstumskomplexe zu erhalten, keinesfalls aber für eine Neuentwicklung. Einspeisung von Umgebungswasser in das Moorinnere muss aber in einem natürlichen Hochmoor ausgeschlossen bleiben. Zusammengefasst ergibt sich in einem Szenario nach erfolgter Renaturierung für 2050 folgende Flächenverteilung: 50 % dichter Lagg- und Moorwald im breiten Randbereich (Nieder- und Übergangsmoor). 50 % Hochmoor (mittleres und oberes Randgehänge und Moorweite), davon: 43 % lichte Kiefern-Birken-Hochmoorheide 20 % Heide mit nur einzeln stehenden Bäumen 20 % Kermi-Komplex mit Baumstreifen 17 % stabile offene Moorweite mit Sphagnum-Wachstumskomplex. Für den Schutz des Schwarzen Moores ist die Wiederherstellung eines nassen Randlaggs prioritär, in der Moorweite sollte die natürliche Entwicklung nicht gestört werden. Der Moorpfad zur Besucherlenkung verläuft überwiegend am Rand der Moorfläche, die offen bis halboffen bleibt.
    Description: The Schwarze Moor in the Rhön mountains is the only Kermi bog in Central Europe. The Kermi structures were created by low temperatures during the Middle Ages, deforestation, extensive pasturing of the high plateau and a stream at its southern border, which stopped its horizontal expansion. The lateral growth barrier led to a higher rate of peat accumulation in the center and, thus, to an unusually steep slope along the bog boarder. The bog lies in the climatic border zone for raised bogs, so that without addition of water input from the surroundings the formation of a raised bog is only barely possible. Up until 1900, the bog was mainly open and since then trees, Carpathian Birch and Scots pine have increasingly colonized the site. Since 1924, different authors from different periods have discussed the causes: changes in climate, global warming with decreasing precipitation, nutrient input, reforestation of the peripheral slope and finally the drainage of the surrounding area and the deflection of the natural input from the lagg zone. The combination of these causes affected the different areas (hydrotopes) differently. These differences are shown in the vegetation map from Gies (1972). In the heated discussion about harvesting wood to “save” the open bog, it is often overlooked that the trees are a result of the increasing dryness not the reason for it. A permanent high water table is necessary for peat moss growth, allowing the peat mosses to compete with the dwarf shrubs. The heath, crowberries and cranberries carry mycorrhiza and their symbiosis fungi cannot live in the anoxic conditions of saturated peat soils. The precipitation is still sufficient to preserve existing vegetation complexes, but not enough to allow for new development. Input from the surrounding water into the bog is not an option in a near-natural bog. A scenario “2050” was developed after a restoration and foresees the following distribution of vegetation communities: 50 % birch forest in the lagg and mixed pine and birch forests of the lower border fringe slope (fen and transitional bogs). 50 % bog (middle and upper marginal slope of an upland moor) with the following area distribution: •43 % heath-savanna, •20 % heath with single trees •20 % Kermi complex trees and dwarf shrubs dominate the linear peat hummocks •17 % Sphagnum complexes.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; Hochmoorwachstum ; Zwergstrauch Konkurrenz ; Niederschlagsentwicklung ; Mykorrhiza ; Szenario 2050 ; bog growth ; dwarf shrub competition ; precipitation development ; Mycorrhiza ; Scenario 2050
    Language: German
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    Zitternde Böden und brennender Schlamm: die Wahrnehmung von Moor und Torf bei den Römern (2022)
    Details
    Publication Date: 2023-05-22
    Description: Es ist eine interessante wissenschaftsgeschichtliche und kulturhistorische Frage, wie die Römer Moore und andere Feuchtgebiete wahrgenommen haben und ob sie Torf kannten. Es gibt kein ursprüngliches lateinisches Wort für die Substanz Torf, aber das verwundert nicht: In den meisten Sprachen ist ein Wort für Torf erst recht spät entstanden. In den Werken von Plinius dem Älteren (24-79 CE) und Tacitus (56-120 CE) gibt es Verweise auf „zitternde Böden“, „schwimmende Inseln“, „brennenden Schlamm“ und „brennende Böden“, die wahrscheinlich von Moor und Torf handeln. Des Weiteren gibt es archäologische Hinweise, dass die römischen Ingenieure, die die Fossa Corbulonis im Westen der Niederlande konstruiert haben, Eigenschaften von Torf kannten. In dieser Studie werden relevante römische Texte und archäologische Funde in ihrem landschaftlichen Kontext kurz vorgestellt und evaluiert.
    Description: An interesting question in the history of culture and science is how the Romans perceived peatlands and other wetlands, and whether they knew ‘peat’ as a substance. The Latin language does not have a word for peat, but this is not surprising, as in most languages a word for the substance appeared rather late. In their works, Pliny the Elder (24-79 CE) and Tacitus (56-120 CE) mention “trembling soils”, “floating islands”, “burning mud” and “burning soils”, which may refer to peatlands and peat. Furthermore, there are archaeological indications that the Roman engineers who constructed the Fossa Corbulonis in the western Netherlands knew the substance and some of its properties. This paper evaluates briefly relevant Roman texts and archaeological finds within the context of the natural landscape.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; ddc:809.93352971 ; Feuchtgebiete ; Fossa Corbulonis ; historische Texte ; Kulturgeschichte ; Plinius der Ältere ; Tacitus ; cultural history ; historical texts ; Pliny the Elder ; wetlands
    Language: German
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    Schrittweise Wasserspiegelanhebung in Mooren als effektive, flächenwirksame Maßnahme zum Erreichen der Pariser Klimaschutzziele in Nordostdeutschland (2022)
    Details
    Publication Date: 2023-05-22
    Description: Für die Umsetzung der Klimaschutzziele auf Moorflächen fehlt in der Bevölkerung die Akzeptanz, Moor zu vernässen. Das bedingt einen zu hohen Aufwand für wasserrechtliche Genehmigungen. Wenn alle Wiedervernässungen über wasserrechtliche Genehmigungen umgesetzt werden müssten, wären die Ziele für Brandenburg und Mecklenburg-Vorpommern bei weitem nicht zu erreichen. Vorgeschlagen wird der Verzicht auf aufwendige Genehmigungsverfahren, was zu einer deutlichen Beschleunigung führt. Die Akzeptanz kann durch Zwischenstauziele deutlich verbessert werden. Innerhalb von 9 Jahren könnten für Brandenburg und Mecklenburg-Vorpommern der Großteil aller Kleinstauanlagen in einen funktionstüchtigen Zustand versetzt und eine Tiefabsenkung des Wasserspiegels vermieden werden. Die geschätzten Kosten liegen für Brandenburg bei 66 Mio. h und für Mecklenburg-Vorpommern bei 38 Mio. h, was z. B. aus Bundesmitteln des Aktionsprogramms „natürlicher Klimaschutz“ (siehe auch: Kabinettsbeschluss zur nationalen Strategie zum Schutz von Mooren) zu finanzieren wäre.
    Description: The implementation of the climate protection goals on peatlands faces a number of obstacles. Above all, the acceptance of wet peatlands by the population and the high cost of water rights permits are bottlenecks in the transformation process. If all rewetting measures had to be implemented via water law permits, the goals for Brandenburg and Mecklenburg-Vorpommern would be far from being achieved. However, there are ways of simplifying and dispensing with approval procedures that can lead to a significant acceleration. Acceptance can be significantly improved with a step-by-step approach through the definition of intermediate storage targets. With the proposed procedure, the majority of all small weirs in Brandenburg and Mecklenburg-Vorpommern could be brought into a functional state within 9 years and a deep lowering of the water level could be avoided. The estimated costs are h66 million for Brandenburg and h38 million for Mecklenburg-Vorpommern, what can be financed e.g. from the federal funds of the action program “natural climate protection”.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; ddc:363.7 ; Kleinstauanlagen ; Genehmigungsverfahren ; natürlicher Klimaschutz ; Transformation ; Brandenburg ; Mecklenburg-Vorpommern ; small weirs ; approval procedures ; natural climate protection ; Moor ; peatland
    Language: German
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    Feuchtgebiete in Mythos und Religion alter Kulturen: eine Einführung (2022)
    Details
    Publication Date: 2023-05-22
    Description: Die Erforschung von Feuchtgebieten im historischen Kontext wirft Fragen auf, die ohne Kombination natur- und geisteswissenschaftlicher Methoden nicht beantwortbar sind. Hierbei bieten, bedingt durch Überlieferungsschwierigkeiten und terminologische Unklarheiten, die Kulturen in Vorderasien und am Mittelmeer eine besondere Herausforderung. Wir versuchen eine Inventur zu erstellen, wie Feuchtgebiete in diesen alten Kulturen empfunden wurden, und analysieren einige Beispiele aus mythologischen bzw. religiösen Quellen.
    Description: The study of wetlands in a historical context leads to questions that cannot be answered without the combination of natural and human sciences. In this frame, the cultures of the Near East and the Mediterranean are – because of preservation of sources and unclarities of terminology – a special challenge. We try to inventory how ancient cultures perceived wetlands and analyse some examples from mythological and religious sources.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; ddc:809.93352971 ; ddc:930 ; ddc:201.3 ; Altes Ägypten ; Antike ; Mythologie ; Nahost ; Religion ; Römer ; Ancient Egypt ; Antiquity ; Near East ; Mythology ; Romans
    Language: German
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    Das Moorschutzfachkonzept Brandenburgs – wie gelingt der Klimaschutz auf Moorböden in der Praxis? (2022)
    Details
    Publication Date: 2023-05-22
    Description: Die Bund-Länder-Zielvereinbarung Moorbodenschutz von 2021 gibt bis 2030 deutschlandweit 5 Mio. t CO2-eq./Jahr Emissionseinsparung aus Mooren vor, was für brandenburgische Moore einer Einsparung von 710.000 t CO2-eq./Jahr entspricht. Für die Umsetzung in Brandenburg wurde ein notwendiger Transformationspfad ermittelt, nachdem aber bis 2030 bereits mehr als 1,1 Mio. t CO2-eq./Jahr eingespart werden sollten. Für das Land Brandenburg setzt ein Klimaplan die Transformationsziele. Danach hat die Landwirtschaft allein durch die Umsetzung der Moorschutzmaßnahmen auf großer Fläche die Chance auf Klimaneutralität bis 2045. Als Zuarbeit für den brandenburgischen Klimaplan wurden GIS-technische Umsetzungsvarianten und die zur Emissionsminderung wirksamsten Maßnahmen ermittelt. Danach besteht von den 6,3 Mio. t CO2-eq./Jahr Gesamtemissionen aus Mooren Brandenburgs unter optimalen Bedingungen ein Einsparungspotenzial von 5,1 Mio. t CO2-eq./Jahr (Thünen-Institut: 5,4 Mio. t CO2-eq./Jahr). Unter Berücksichtigung des Klimawandels werden 4,0 Mio. t CO2-eq./Jahr (Thünen-Institut: 4,3 Mio. t CO2-eq./Jahr) als mindestens machbare Einsparungsmenge eingeschätzt. Darüber hinaus nimmt die Abhängigkeit des Umsetzungserfolges vom Wasserdargebot stetig zu. Die höchste Wirksamkeit hat die großflächige Nachrüstung und Erneuerung von Stauanlagen zur Vermeidung von Tiefentwässerung in Kombination mit einer verbesserten landwirtschaftlichen Förderung. Entscheidend hierbei ist die Minimierung des Genehmigungsaufwandes. Vor allem mit attraktiven landwirtschaftlichen Förderprogrammen lässt sich die erforderliche große Flächenwirkung erzielen, wo genehmigungsbasierte Vorhaben an ihre Grenzen stoßen. Die größte Sogwirkung im anstehenden Transformationsprozess entfalten marktwirtschaftlich integrierte Wertschöpfungsketten. Die Schwerpunkte des Finanzmittelbedarfs werden in folgenden Bereichen gesehen: Wirtschaftsförderung, Verwertung und Technikentwicklung, Ausgleich- und Entschädigung, Wasserbaumaßnahmen und Schutz- und Anpassungsmaßnahmen.
    Description: The federal and state target agreement on peatland soil protection of 2021 specifies 5 million t CO2-eq./year emission savings from peatlands across Germany by 2030, which, broken down to Brandenburg, corresponds to a saving of 710,000 t CO2-eq./year. For the implementation in Brandenburg, a necessary transformation path was determined, after which, however, more than 1.1 million t CO2-eq./year should already be saved by 2030. A climate plan sets the transformation targets for the state of Brandenburg. According to this plan, agriculture has the chance to achieve climate neutrality by 2045 simply by implementing peatland protection measures over a large area. As input for the Brandenburg climate plan, implementation variants and the most effective measures for reducing emissions were determined using GIS technology. According to this, of the 6.3 million t CO2 eq./year total emissions from peatlands in Brandenburg, under optimal conditions there is a savings potential of 5.1 million t CO2 eq./year (Thünen-Institut: 5.4 million t CO2 eq./year). Taking climate change into account, 4.0 million t CO2 eq./year (Thünen-Institut: 4.3 million t CO2 eq./year) are estimated as at least feasible savings. Furthermore, the dependency of the implementation success on the water supply is constantly increasing. The highest effectiveness is achieved by large-scale retrofitting of dams to prevent deep drainage in combination with improved agricultural support. The decisive factor here is the minimisation of the approval effort. Attractive agricultural subsidy programmes in particular can achieve the necessary large-scale effect where permit-based individual projects reach their limits. The greatest pull in the upcoming transformation process comes from integrated value chains in a market economy. The focal points of the need for financial resources are seen in the following areas: Economic promotion, utilisation and technology development, compensation, water construction measures and protection and adaptation measures.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:553.21 ; Moorschutz ; Klimaplan ; Umsetzung ; Transformation ; Varianten ; mire protection ; climate plan ; implementation ; variants ; Moor ; Torf ; peatland ; peat
    Language: German
    Type: doc-type:article , publishedVersion
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    Alles Matsch? – Bildungs- und Öffentlichkeitsarbeit in Mooren (2022)
    Details
    Publication Date: 2023-06-05
    Description: Moore sind in aller Munde. Stehen wir doch alle vor den globalen Herausforderungen wie Klimawandel und Biodiversitätsverlust. Die im vergangenen Jahr noch schnell beschlossene Moorschutzstrategie der Bundesregierung wurde zunächst ohne nachhaltigen Vermittlungsansatz zur Diskussion gestellt. Das Emsland Moormuseum beteiligte sich daraufhin mit einer entsprechenden Stellungnahme. Diese wurde eins zu eins im finalen Beschluss berücksichtigt. Nun gilt es die Bildungs- und öffentlichkeitsarbeit in Mooren im Rahmen einer gemeinsamen Bildungsstrategie weiter zu diskutieren und auszubauen, so dass das Potenzial einer ganzheitlichen Moorpädagogik mit Kopf, Herz und Hand eine Brücke zwischen Wissen und Handeln schlägt.
    Description: Everyone is talking about peatlands. We are all facing global challenges, such as climate change and loss of biodiversity. The federal government‘s peatland conservation strategy, which was quickly adopted last year, was initially released for discussion without a sustainable education approach. The Emsland Moormuseum issued a critical statement and thus substantially changed the final policy. Now it is essential to discuss and advance the education and publicity in peatlands together. For this, the full potential of an integral peatland education, which combines head, heart and hands to build a bridge between knowledge and action should be used.
    Description: SUB Göttingen, DGMT
    Description: research
    Keywords: ddc:333.7 ; Moorpädagogik ; Bildung für nachhaltige Entwicklung ; Moorbewusstsein ; Vermittlungsarbeit in Mooren ; Umweltbildung ; peatland education ; education for sustainable development ; peatland awareness ; mediation in peatlands ; environmental education
    Language: German
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  • 72
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    MoorIS: Inhalte und zukünftige Möglichkeiten des Moorinformationssystems für Niedersachsen (2022)
    Details
    Publication Date: 2023-06-05
    Description: Die Bundesrepublik Deutschland hat im Klimaschutzgesetz formuliert, bis zum Jahr 2045 eine Treibhausgasneutralität anzustreben. Die Änderung der Landnutzung auf Moorstandorten wird als integraler Bestandteil der Zielsetzung angesehen. Durch die landwirtschaftliche Nutzung von Moorstandorten werden 53 Millionen Tonnen Treibhausgase pro Jahr emittiert. Damit ist die Nutzung der entwässerten Moore der größte einzelne Treibhausgasemittent außerhalb des Energiesektors. Die Verfügbarkeit von Daten und Informationen für ein klimaschonendes Management der Moorflächen ist essentiell für die langfristige Reduktion der Emissionen aus Mooren und den Erhalt weiterer Landschaftsfunktionen wie der Biodiversität. Die Landesfläche Niedersachsens beheimatet ein Drittel der deutschen Moorflächen. Damit obliegt dem Bundesland eine wichtige Verantwortung in der Reduktion der Emissionen auf Mooren und kohlenstoffreichen Böden. Das Moorinformationssystem „MoorIS“ (https://mooris-niedersachsen.de/) stellt behördenübergreifende Daten und Informationen zu den niedersächsischen Mooren zur Verfügung. Diese umfassen neben landesweiten kartographischen Aufbereitungen und Bohrungen auch Informationen zu Moorgebieten und Moorprojekten, eine Übersicht und Arbeitshilfen für Moormanagementoptionen. Ergänzt wird dies durch moorkundliche Erläuterungen sowie Ausführungen zur Nutzung und Geschichte der niedersächsischen Moore. Das Zielpublikum des MoorIS umfasst vor allem Fachpublikum mit Vorkenntnissen zu Mooren. Das reicht von Verwaltungen, Entscheidungstragenden in Politik und Wirtschaft, über Verbände und Vereine im Natur- und Umweltschutz, Planungsbüros bis hin zu Forschung und Lehre. Gleichzeitig bietet die Webseite auch Informationen zu Niedersachsens Mooren für Nutzende mit wenig bis keinen Vorkenntnissen. Die Webseite umfasst vor allem landesweite Karten und Auszüge aus Datenbanken mehrerer Landesbehörden. In zukünftigen Erweiterungen des Informationssystems könnten Daten, die im Rahmen von Moorprojekten erhoben wurden, integriert werden. Damit würden vor allem lokale Informationen zum Boden und zur Hydrologie erfasst werden. Diese Integration von Daten Dritter erfordert eine enge behördliche Zusammenarbeit, um bestehende Standards und Datenstrukturen nutzen zu können und doppelte Datenhaltungen zu vermeiden. Im Moorinformationssystem wird die Bereitstellung von umfassenden sowie belastbaren Informationen angestrebt, sodass eine breite Informationsbasis für zukünftige Entscheidungen im Sinne des Schutzes der niedersächsischen Moore zur Verfügung stehen wird.
    Description: Germany aims to become greenhouse gas neutral by 2045. An integral part of reaching this goal will be changing the land use of peatlands. The agricultural use of peatlands in Germany results in the emission of 53 Mio. T greenhouse gases each year, making peatlands the single largest emitter of GHGs outside of the energy sector. In order to reduce GHG Emissions from peatlands and to achieve other environmental objectives like biodiversity goals, stakeholders in peatland management will need access to reliable site data as well as information about climate-friendly management options. With over one third of the peatland area in Germany, Lower Saxony plays an important role in reducing GHG emissions from peatlands. The peatland information system for Lower Saxony (MoorIS) is a website, which bundles peatland data from different institutions, i.e. nature protection and geological institutes. The content of the website covers maps, detailed information on peatland areas and peatland projects, best practices documents on various climate-friendly management options as well as general texts on peatland management, ecology and regional land use. Furthermore, an online form, which will allow stakeholders to upload basic information about new peatland related projects, will allow users to contribute information to the website. The main target group for MoorIS is users with some previous peatland knowledge, i.e. administrative authorities, stakeholder in politics and industry, non-governmental organizations, planning offices. General texts on peatland topics will allow also users with little previous knowledge to acquire general background knowledge of peatlands in Lower Saxony. Currently, the website focusses on providing small-scale information in the form of maps and databases from various state institutions. However, future expansion of the website could integrate detailed project data. This addition would include local data, such as soil and hydrology data, compiled by management projects. The integration of additional data would entail cooperation with institutes that have existing databases to avoid the duplication of data. Overall, MoorIS aims to provide reliable and comprehensive data to enable stakeholders to plan and manage Lower Saxony’s peatlands in a climate-friendly manner.
    Description: SUB Göttingen, DGMT
    Description: report
    Keywords: ddc:553.21 ; Internetplattform ; Karten ; Handlungsempfehlungen ; Moormanagement ; Moorschutz ; Internet platform ; maps ; best practice guides ; peatland management ; peatland conservation
    Language: German
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    A Coulomb Stress Response Model for Time‐Dependent Earthquake Forecasts (2022)
    Details
    Publication Date: 2023-01-21
    Description: Seismicity models are probabilistic forecasts of earthquake rates to support seismic hazard assessment. Physics‐based models allow extrapolating previously unsampled parameter ranges and enable conclusions on underlying tectonic or human‐induced processes. The Coulomb Failure (CF) and the rate‐and‐state (RS) models are two widely used physics‐based seismicity models both assuming pre‐existing populations of faults responding to Coulomb stress changes. The CF model depends on the absolute Coulomb stress and assumes instantaneous triggering if stress exceeds a threshold, while the RS model only depends on stress changes. Both models can predict background earthquake rates and time‐dependent stress effects, but the RS model with its three independent parameters can additionally explain delayed aftershock triggering. This study introduces a modified CF model where the instantaneous triggering is replaced by a mean time‐to‐failure depending on the absolute stress value. For the specific choice of an exponential dependence on stress and a stationary initial seismicity rate, we show that the model leads to identical results as the RS model and reproduces the Omori‐Utsu relation for aftershock decays as well stress‐shadowing effects. Thus, both CF and RS models can be seen as special cases of the new model. However, the new stress response model can also account for subcritical initial stress conditions and alternative functions of the mean time‐to‐failure depending on the problem and fracture mode.
    Description: Plain Language Summary: One of the most pressing questions in earthquake physics is understanding where and when earthquakes occur and how seismicity is related to stress changes in the Earth's crust. This question is even more important today because humans are increasingly influencing stresses in the Earth by exploiting the subsurface. So far, two classes of physics‐based seismicity models have been used primarily. One assumes instantaneous earthquake occurrence when stress exceeds a threshold, and the other is based on the nucleation of earthquakes according to friction laws determined in the laboratory. Both models are very different in their approaches, have advantages and disadvantages, and are limited in their applicability. In this paper, we introduce a new concept of seismicity models, which is very simple and short to derive and combines the strengths of both previous models, as shown in various applications to human‐related seismicity. The forecasts of both traditional models turn out to be special cases of the new model.
    Description: Key Points: We introduce a modified Coulomb Failure seismicity model in which a mean time‐to‐failure replaces instantaneous triggering. The model explains the main features of time‐dependent seismicity, including aftershock activity and stress shadow effects. As a special case, it includes the rate‐state model solutions but can also handle subcritical stresses and other fracture types.
    Description: European Unions 2020 research and innovation programme
    Description: https://github.com/torstendahm/tdsr
    Keywords: ddc:551.22 ; seismicity ; physics based model ; earthquake physics
    Language: English
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    X‐ray diffraction with micrometre spatial resolution for highly absorbing samples (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-01-21
    Description: X‐ray diffraction with high spatial resolution is commonly used to characterize (poly)crystalline samples with, for example, respect to local strain, residual stress, grain boundaries and texture. However, the investigation of highly absorbing samples or the simultaneous assessment of high‐Z materials by X‐ray fluorescence have been limited due to the utilization of low photon energies. Here, a goniometer‐based setup implemented at the P06 beamline of PETRA III that allows for micrometre spatial resolution with a photon energy of 35 keV and above is reported. A highly focused beam was achieved by using compound refractive lenses, and high‐precision sample manipulation was enabled by a goniometer that allows up to 5D scans (three rotations and two translations). As experimental examples, the determination of local strain variations in martensitic steel samples with micrometre spatial resolution, as well as the simultaneous elemental distribution for high‐Z materials in a thin‐film solar cell, are demonstrated. The proposed approach allows users from the materials‐science community to determine micro‐structural properties even in highly absorbing samples.
    Description: A demonstration of high‐resolution micro X‐ray diffraction at high photon energies for highly absorbing samples.
    Keywords: ddc:548 ; X‐ray diffraction ; high spatial resolution ; high photon energy ; X‐ray fluorescence ; goniometers
    Language: English
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    Sediment Release in the Benguela Upwelling System Dominates Trace Metal Input to the Shelf and Eastern South Atlantic Ocean (2022)
    Details
    Publication Date: 2023-01-21
    Description: Upwelling of subsurface waters injects macronutrients (fixed N, P, and Si) and micronutrient trace metals (TMs) into surface waters supporting elevated primary production in Eastern Boundary Upwelling Regions. The eastern South Atlantic features a highly productive shelf sea transitioning to a low productivity N‐Fe (co)limited open ocean. Whilst a gradient in most TM concentrations is expected in any off‐shelf transect, the factors controlling the magnitude of cross‐shelf TM fluxes are poorly constrained. Here, we present dissolved TM concentrations of Fe, Co, Mn, Cd, Ni, and Cu within the Benguela Upwelling System from the coastal section of the GEOTRACES GA08 cruise. Elevated dissolved Fe, Co, Mn, Cd, Ni, Cu and macronutrient concentrations were observed near shelf sediments. Benthic sources supplied 2.22 ± 0.99 μmol Fe m−2 day−1, 0.05 ± 0.03 μmol Co m−2 day−1, 0.28 ± 0.11 μmol Mn m−2 day−1 and were found to be the dominant source to shallow shelf waters compared to atmospheric depositions. Similarly, off‐shelf transfer was a more important source of TMs to the eastern South Atlantic Ocean compared to atmospheric deposition. Assessment of surface (shelf, upper 200 m) and subsurface (shelf edge, 200–500 m) fluxes of Fe and Co indicated TM fluxes from subsurface were 2–5 times larger than those from surface into the eastern South Atlantic Ocean. Under future conditions of increasing ocean deoxygenation, these fluxes may increase further, potentially contributing to a shift toward more extensive regional limitation of primary production by fixed N availability.
    Description: Key Points: Shelf sediments release redox‐sensitive trace metals (TMs) to overlying oxygen‐depleted waters in the Benguela Upwelling System. Sediment‐derived TMs are upwelled and laterally transported constituting a major source to shelf waters and to the eastern South Atlantic. Subsurface fluxes of dissolved Fe and Co from the shelf edge play an important role in supplying Fe and Co to the eastern South Atlantic.
    Description: China Scholarship Council, CSC http://dx.doi.org/10.13039/501100004543
    Description: GEOMAR and German Research Foundation
    Description: German DFG
    Description: German Research Foundation
    Description: https://doi.pangaea.de/10.1594/PANGAEA.947275
    Keywords: ddc:551 ; dissolved trace metals ; Benguela Upwelling Systems ; fluxes ; Eastern Boundary Upwelling Systems Regions
    Language: English
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    Experimentally Induced Thermal Fatigue on Lunar and Eucrite Meteorites—Influence of the Mineralogy on Rock Breakdown (2022)
    Details
    Publication Date: 2023-01-21
    Description: Thermal fatigue has been proven to be of fundamental importance for the nature and evolution of surfaces of airless bodies in the solar system. It is a rock erosive process acting in conjunction with meteoroid bombardment. We set up an experiment to simulate the diurnal temperature variation at 1 AU of centimeter sized sample cubes using a liquid nitrogen cooled cryostat, allowing to study unexplored conditions, that is, high vacuum and temperatures of 200 K similar to those occurring on the Moon. The sample cubes are investigated using scanning electron microscopy and micro computed tomography scans before and after 10, 20, 50, 100, and 400 total cycles. Cycling of the lunar anorthosite Northwest Africa (NWA) 11273 and the eucrite NWA 11050 reveal different behaviors: Whereas NWA 11273 responds to the cycling with micro‐flaking of tenth‐of‐µm‐sized grains on its surface and only limited crack growth, the eucrite NWA 11050 is less affected by micro‐flaking but the growth of cracks is observed to occur throughout the whole experiment. The rate of crack formation and growth is lower when compared to previously reported results on ordinary and carbonaceous chondritic samples carried out under nitrogen atmosphere and above 250 K. We propose that the size of particles and their rate of production by thermal fatigue highly depends on the mineralogy of the exposed rock and areas with mature rocks are prone to produce fine‐grained soil, while primary rocks such as basalts are likely to produce blocky regolith in a first step.
    Description: Plain Language Summary: Thermal fatigue—the fatigue of a material due to temperature variation—is important for the breakdown of rocks on the surface of planetary bodies such as the Moon, asteroids, and also on the Earth and the formation of a fine‐grained soil, called the regolith. With an improved experimental setup, we simulate the diurnal temperature variations at a solar distance of 1 AU under high vacuum conditions between 200 and 375 K for the lunar anorthosite breccia Northwest Africa (NWA) 11273 and the eucritic basalt NWA 11050. We show that both types of rocks respond different to these temperature excursions: The basaltic eucrite forms cracks over the course of 400 cycles and the lunar anorthosite tends to flake off tenth‐of‐µm‐sized grains with only limited cracking. The overall obtained cracking rates are lower when compared to those from previous experiments under nitrogen atmosphere, indicating the retrieved breakdown rates are lower than previously reported and the type of resulting soil depends strongly on the mineralogy of the exposed rock.
    Description: Key Points: We report on an updated experimental setup to simulate thermal fatigue in high vacuum instead of nitrogen atmosphere to reflect natural conditions. The crack formation and growth rates differ between the lunar anorthosite and eucritic basalt and are generally 〈50% of those reported previously. We propose that the resulting regolith depends highly on the mineralogy of starting materials, which control the breakdown of the rock.
    Description: Alexander von Humboldt Foundation
    Description: https://doi.org/10.26022/IEDA/112505
    Keywords: ddc:549.112 ; thermal fatigue ; eucrite ; Moon ; regolith ; thermal breakdown
    Language: English
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    Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil‐Bound Organic Matter (2022)
    Details
    Publication Date: 2023-01-21
    Description: Fossil‐bound organic material holds great potential for the reconstruction of past changes in nitrogen (N) cycling. Here, with a series of laboratory experiments, we assess the potential effect of oxidative degradation, fossil dissolution, and thermal alteration on the fossil‐bound N isotopic composition of different fossil types, including deep and shallow water scleractinian corals, foraminifera, diatoms and tooth enamel. Our experiments show that exposure to different oxidizing reagents does not significantly affect the N isotopic composition or N content of any of the fossil types analyzed, demonstrating that organic matter is well protected from changes in the surrounding environment by the mineral matrix. In addition, we show that partial dissolution (of up to 70%–90%) of fossil aragonite, calcite, opal, or enamel matrixes has a negligible effect on the N isotopic composition and N content of the fossils. These results suggest that the isotopic composition of fossil‐bound organic material is relatively uniform, and also that N exposed during dissolution is lost without significant isotopic discrimination. Finally, our heating experiments show negligible changes in the N isotopic composition and N content of all fossil types at 100°C. At 200°C and hotter, any N loss and associated nitrogen isotope changes appear to be directly linked to the sensitivity of the mineral matrix to thermal stress, which depends on the biomineral type. These results suggest that, so long as high temperature does not compromise the mineral structure, the biomineral matrix acts as a closed system with respect to N, and the N isotopic composition of the fossil remains unchanged.
    Description: Plain Language Summary: The ratio of the heavy and light isotopes of nitrogen (15N and 14N) in the organic material contained within the mineral structure of fossils can be used to reconstruct past changes in biological and chemical processes. With a series of laboratory experiments, we evaluate the potential effects of chemical conditions, fossil dissolution, and heating on the nitrogen isotopic composition (15N/14N ratio) of corals, foraminifera, diatoms and tooth enamel. Our results indicate that these processes do not have a significant effect on the 15N/14N of fossils, suggesting that the mineral matrix provides a barrier that isolates a fossil's organic nitrogen from the surrounding environment, preventing alteration of its 15N/14N. In addition, we show that if part of the fossil‐bound organic nitrogen is exposed by dissolution or heating, it is lost without affecting the 15N/14N of the organic material that remains in the mineral. These findings imply that the original 15N/14N ratio incorporated by the organism is preserved in the geologic record. Therefore, measurements of the nitrogen isotopes on fossils can provide faithful biological, ecological, and environmental information about the past.
    Description: Key Points: Fossil‐bound organic matter is well protected by the mineral matrix from chemical changes in the surrounding environment. Partial dissolution of fossil calcite, aragonite, opal, and enamel has a negligible effect on their N isotopic composition and N content. During heating, fossil N content and isotopic composition remains unchanged if the structure of the inorganic matrix is not compromised.
    Description: Max Planck Society
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: US National Science Foundation
    Description: Paul Crutzen Nobel Prize Fellowship
    Description: https://doi.org/10.5281/zenodo.6884681
    Keywords: ddc:551.9 ; nitrogen isotopes ; diagenesis ; foraminifera ; corals ; diatoms ; teeth
    Language: English
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    Dynamics of Greenhouse Gases (CH4 and CO2) in Meromictic Lake Burgsee, Germany (2022)
    Details
    Publication Date: 2023-01-21
    Description: Extraordinary amounts of greenhouse gases can be stored within the monimolimnion of meromictic lakes, that is, in the water body which is excluded from mixing events. Lake Burgsee (Thuringia, Germany) is a shallow (depth 〈5 m) lake with a approximately 24 m deep sinkhole, which is fed by underground brine sources and has formed such a monimolimnion. We investigated the carbon dioxide and methane dynamics in this meromictic lake, from production potentials in the sediment via concentrations in the monimolimnion and mixolimnion to emissions to the atmosphere. In the monimolimnion, we found one of the highest methane concentrations (up to 〉5 mmol L−1) ever reported for a natural freshwater lake, while carbon dioxide concentrations in the water and methane production rates in the sediments were rather ordinary and within the range of holomictic eutrophic lakes. At the thermocline, gas concentrations accumulated to approximately 100 μmol L−1 CH4 and 80–230 μmol L−1 CO2. Estimated fluxes to the atmosphere reached considerable 3.5 mmol CH4 m−2 d−1 and 1.5 mmol CO2 m−2 d−1 above the sinkhole and 0.8 mmol CH4 m−2 d−1 and 0.4 mmol CO2 m−2 d−1 above the near‐by shallow lake center in 2018. Our results demonstrate that lakes in natural brine areas may provide significant storages and releases of greenhouse gases and require further investigation.
    Description: Plain Language Summary: In meromictic lakes, the deepest water layer, the monimolimnion, is stagnant and not included in seasonal water circulation. Organic matter continuously sinks down into the oxygen‐free monimolimnion, where it is decomposed into the final gaseous products carbon dioxide (CO2) and methane (CH4). Lake Burgsee is a meromictic shallow (depth 〈5 m), brine‐fed lake with a approximately 24 m deep sinkhole. At the bottom of the narrow sinkhole, salinities are as high as in brackish water and cause a chemical stratification of the water body—a monimolimnion—in approximately 18 m depth. CH4 concentrations above the sediment reach 〉5 mmol L−1, which is more than one order of magnitude higher than at the water surface and among the highest CH4 concentrations found in freshwater lakes worldwide. Further, emissions of CH4 and CO2 from the water to the atmosphere were considerable in 2018, and about four times higher above the sinkhole than above the shallow lake center. These results demonstrate, that lakes in natural brine areas may store and release significant amounts of greenhouse gases and require further investigation.
    Description: Key Points: In the urban meromictic Lake Burgsee, methane production potentials in the sediment are similar to eutrophic holomictic lakes. At its deepest site, it contains one of the highest methane concentrations (〉5 mmol L−1 CH4) ever reported for a natural freshwater lake. Lake Burgsee emits up to 〉3 mmol m−2 d−1 CH4 to the atmosphere above the sinkhole and 〈1 mmol m−2 d−1 CH4 at a near‐by shallow site.
    Keywords: ddc:551 ; meromictic lake ; sinkhole ; salinity ; greenhouse gases ; methane flux ; carbon dioxide
    Language: English
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    Vertical SOC distribution and aromatic carbon in centuries old charcoal‐rich Technosols (2022)
    Bonhage, Alexander ; Raab, Thomas ; Schneider, Anna ; [et al.]
    Blackwell Publishing Ltd | Oxford, UK
    Details
    Publication Date: 2023-01-21
    Description: Charcoal‐rich Technosols on century‐old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long‐term influence of biochar amendment and the post‐wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north‐western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy‐based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA‐derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self‐humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA‐derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non‐pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now. Highlights BC to TOC ratio and high resolution vertical SOC distribution in 52 RCH sites were studied. RCH soils non‐BC pool was potentially different to reference soils. RCH soils feature TOC accumulation in the topmost horizon. There is BC translocation into buried soils on RCH sites.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:631.4 ; benzene polycarboxylated acid marker (BPCA) ; black carbon ; charcoal degradation ; charcoal kiln ; pyrogenic carbon ; relict charcoal hearth ; biochar
    Language: English
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    High Precision Femtosecond Laser Ablation ICP‐MS Measurement of Benthic Foraminiferal Mn‐Incorporation for Paleoenvironmental Reconstruction: A Case Study From the Plio‐Pleistocene Caribbean Sea (2022)
    Details
    Publication Date: 2023-01-21
    Description: Closure of the Central American Seaway (CAS) and hydrology of the Caribbean Sea triggered Northern Hemisphere Glaciation and played an important role in the Pliocene to modern‐day climate re‐establishing the deep and surface ocean currents. New data on Mn/Ca obtained with femtosecond laser ablation inductively coupled plasma mass spectrometry on well‐preserved tests of the epibenthic foraminifer Cibicidoides wuellerstorfi and infaunal C. mundulus contribute to the interpretation of paleoenvironmental conditions of the Caribbean Sea between 5.2 and 2.2 Ma (million years) across the closure of the CAS. Hydrothermal activity at the Lesser Antilles may be a primary source of Mn in the well‐oxygenated Plio‐Pleistocene Caribbean Sea. Incorporation of Mn in the benthic foraminifer shell carbonate is assumed to be affected by surface ocean nutrient cycling, and may hence be an indicator of paleoproductivity.
    Description: Plain Language Summary: The closure of the Panama Isthmus caused the expansion of ice sheets in the Northern Hemisphere and changed the water current dynamics and climate in the Caribbean Sea since the Pliocene (∼5.3 million years ago). New Mn/Ca data measured using femtosecond laser ablation inductively coupled plasma mass spectrometry on the deep‐sea benthic foraminifer species Cibicidoides wuellerstorfi and Cibicidoides mundulus help us understand past environmental conditions of the Caribbean Sea prevailed between 5.2 and 2.2 million years ago. While manganese might be sourced from the surrounding hydrothermal vents, its incorporation in the foraminifer shell carbonate might be related to nutrient cycling and may indicate past biological productivity in the ocean.
    Description: Key Points: Femtosecond‐laser ablation inductively coupled plasma mass spectrometry provides a new approach on distinguishing Mn of the ontogenetic shell calcite from Mn of the authigenic coatings. Ontogenetic Mn within the foraminifer shell calcite may result from the regional nutrient cycle. Mn in the deep eastern Caribbean Sea may mainly derive from hydrothermal sources along the Antilles Island Arc.
    Description: MPIC
    Description: https://doi.org/10.17632/bps7nw7922.1
    Keywords: ddc:560 ; manganese ; Cibicidoides wuellerstorfi ; Cibicidoides mundulus ; Central American Seaway ; trace elements ; hydrothermal ; paleoproductivity
    Language: English
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    Domain Auto Finder (DAFi) program: the analysis of single‐crystal X‐ray diffraction data from polycrystalline samples (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-01-21
    Description: This paper presents the Domain Auto Finder (DAFi) program and its application to the analysis of single‐crystal X‐ray diffraction (SC‐XRD) data from multiphase mixtures of microcrystalline solids and powders. Superposition of numerous reflections originating from a large number of single‐crystal domains of the same and/or different (especially unknown) phases usually precludes the sorting of reflections coming from individual domains, making their automatic indexing impossible. The DAFi algorithm is designed to quickly find subsets of reflections from individual domains in a whole set of SC‐XRD data. Further indexing of all found subsets can be easily performed using widely accessible crystallographic packages. As the algorithm neither requires a priori crystallographic information nor is limited by the number of phases or individual domains, DAFi is powerful software to be used for studies of multiphase polycrystalline and microcrystalline (powder) materials. The algorithm is validated by testing on X‐ray diffraction data sets obtained from real samples: a multi‐mineral basalt rock at ambient conditions and products of the chemical reaction of yttrium and nitrogen in a laser‐heated diamond anvil cell at 50 GPa. The high performance of the DAFi algorithm means it can be used for processing SC‐XRD data online during experiments at synchrotron facilities.
    Description: This paper presents the Domain Auto Finder (DAFi) program and its application to the analysis of single‐crystal X‐ray diffraction (SC‐XRD) data from multiphase mixtures of microcrystalline solids and powders. The DAFi algorithm is designed to quickly find subsets of reflections from individual domains in a whole set of SC‐XRD data and neither requires a priori crystallographic information nor is limited by the number of phases or individual domains.
    Keywords: ddc:548 ; single‐crystal domain auto finder ; DAFi ; single‐crystal X‐ray diffraction ; polycrystalline samples ; multiphase mixtures
    Language: English
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    Using Principal Component Analysis of Satellite and Ground Magnetic Data to Model the Equatorial Electrojet and Derive Its Tidal Composition (2022)
    Details
    Publication Date: 2023-01-21
    Description: The intensity of the equatorial electrojet (EEJ) shows temporal and spatial variability that is not yet fully understood nor accurately modeled. Atmospheric solar tides are among the main drivers of this variability but determining different tidal components and their respective time series is challenging. It requires good temporal and spatial coverage with observations, which, previously could only be achieved by accumulating data over many years. Here, we propose a new technique for modeling the EEJ based on principal component analysis (PCA) of a hybrid ground‐satellite geomagnetic data set. The proposed PCA‐based model (PCEEJ) represents the observed EEJ better than the climatological EEJM‐2 model, especially when there is good local time separation among the satellites involved. The amplitudes of various solar tidal modes are determined from PCEEJ based tidal equation fitting. This allows to evaluate interannual and intraannual changes of solar tidal signatures in the EEJ. On average, the obtained time series of migrating and nonmigrating tides agree with the average climatology available from earlier work. A comparison of tidal signatures in the EEJ with tides derived from neutral atmosphere temperature observations show a remarkable correlation for nonmigrating tides such as DE3, DE2, DE4, and SW4. The results indicate that it is possible to obtain a meaningful EEJ spectrum related to solar tides for a relatively short time interval of 70 days.
    Description: Key Points: A novel technique to model the equatorial electrojet (EEJ) based on the principal component analysis of a hybrid ground‐satellite data set. The new modeling matches observations better than the EEJM‐2 model, especially when the Swarm satellites have optimum local time coverage. Time series of migrating and nonmigrating tides amplitude in the EEJ are derived from 70‐day window.
    Description: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior http://dx.doi.org/10.13039/501100002322
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro http://dx.doi.org/10.13039/501100004586
    Description: MEXT Japan Society for the Promotion of Science http://dx.doi.org/10.13039/501100001691
    Keywords: ddc:538.7 ; geomagnetism ; equatorial electrojet ; atmospheric tides
    Language: English
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    Upper Plate Response to a Sequential Elastic Rebound and Slab Acceleration During Laboratory‐Scale Subduction Megathrust Earthquakes (2022)
    Details
    Publication Date: 2023-01-21
    Description: An earthquake‐induced stress drop on a megathrust instigates different responses on the upper plate and slab. We mimic homogenous and heterogeneous megathrust interfaces at the laboratory scale to monitor the strain relaxation on two elastically bi‐material plates by establishing analog velocity weakening and neutral materials. A sequential elastic rebound follows the coseismic shear‐stress drop in our elastoplastic‐frictional models: a fast rebound of the upper plate and the delayed and smaller rebound on the elastic belt (model slab). A combination of the rebound of the slab and the rapid relaxation (i.e., elastic restoration) of the upper plate after an elastic overshooting may accelerate the relocking of the megathrust. This acceleration triggers/antedates the failure of a nearby asperity and enhances the early slip reversal in the rupture area. Hence, the trench‐normal landward displacement in the upper plate may reach a significant amount of the entire interseismic slip reversal and speeds up the stress build‐up on the upper plate backthrust that emerges self‐consistently at the downdip end of the seismogenic zones. Moreover, the backthrust switches its kinematic mode from a normal to reverse mechanism during the coseismic and postseismic stages, reflecting the sense of shear on the interface.
    Description: Plain Language Summary: Subduction zones, where one tectonic plate slides underneath the other, host the largest earthquakes on earth. Two plates with different physical properties define the upper and lower plates in the subduction zones. A frictional interaction at the interface between these plates prevents them from sliding and builds up elastic strain energy until the stress exceeds their strength and releases accumulated energy as an earthquake. The source of the earthquake is located offshore; hence illuminating the plates' reactions to the earthquakes is not as straightforward as the earthquakes that occur inland. Here we mimic the subduction zone at the scale of an analog model in the laboratory to generate analog earthquakes and carefully monitor our simplified model by employing a high‐resolution monitoring technique. We evaluate the models to examine the feedback relationship between upper and lower plates during and shortly after the earthquakes. We demonstrate that the plates respond differently and sequentially to the elastic strain release: a seaward‐landward motion of the upper plate and an acceleration in the lower plate sliding underneath the upper plate. Our results suggest that these responses may trigger another earthquake in the nearby region and speed up the stress build‐up on other faults.
    Description: Key Points: Seismotectonic scale models provide high‐resolution observations to study the surface deformation signals from shallow megathrust earthquakes. Surface displacement time‐series suggest a sequential elastic rebound of the upper plate and slab during great subduction megathrust earthquakes. Slip reversal may be caused by rapid restoration of the upper plate after overshooting and amplified upper plate motion.
    Description: SUBITOP Marie Sklodowska‐Curie Action project from the European Union's EU Framework Programme
    Description: Deutsche Forschungsgemeinschaft
    Description: https://doi.org/10.5880/fidgeo.2022.024
    Keywords: ddc:551.22 ; analog modeling ; megathrust earthquake ; seismic cycle ; elastic rebound ; upper plate ; overshooting
    Language: English
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    Influence of Rarely Mobile Boulders on Channel Width and Slope: Theory and Field Application (2022)
    Details
    Publication Date: 2023-01-25
    Description: Large, rarely mobile boulders are observed globally in mountainous bedrock channels. Recent studies suggest that high concentrations of boulders could be associated with channel morphological adjustment. However, a process‐based understanding of large boulder effects on channel morphology is limited, and data are scarce and ambiguous. Here, we develop a theory of steady‐state channel width and slope as a function of boulder concentration. Our theory assumes that channel morphology adjusts to maintain two fundamental mass balances: (a) grade, in which the channel transports the same sediment flux downstream despite boulders acting as roughness elements and (b) bedrock erosion, by which the channel erodes at the background tectonic uplift rate. Model predictions are normalized by a reference, boulder‐free channel width and slope, accounting for variations due to sediment supply, discharge, and lithology. Models are tested against a new data set from the Liwu River, Taiwan, showing steepening and widening with increasing boulder concentration. Whereas one of the explored mechanisms successfully explains the observed steepening trend, none of the models accuratly account for the observed width variability. We propose that this contrast arises from different adjustment timescales: while sediment bed slope adjusts within a few floods, width adjustment takes a much longer time. Overall, we find that boulders represent a significant perturbation to fluvial landscapes. Channels tend to respond by forming a new morphology that differs from boulder‐free channels. The general approach presented here can be further expanded to explore the role of other hydrodynamic effects associated with large, rarely mobile boulders.
    Description: Plain Language Summary: Large boulders are a significant feature in mountainous landscapes. Recent studies suggested that boulders residing in rivers interfere with the flow and sediment transport, forcing their geometry, specifically width and slope, to change. Our ability to understand and predict such changes is challenged by scarce field data and a general lack of models capable of explaining the processes underlying channel geometry adjustment in the presence of boulders. Here, we develop a theory and several models for the variation of channel width and slope as with channel boulder coverage. Our theory builds on the assumption that the geometry of boulder‐bed channels evolves to a new configuration to maintain steadiness of erosion rate and sediment transport. Predictions from the various models are tested against data from the steep Liwu River in Taiwan. These data show that width and slope increase with more boulders. We find that channel slope increases to overcome the greater resistance to sediment transport due to the boulders. In contrast, the scattered nature of the width data and the overall models inability to explain width variability likely reflect a longer adjustment period for width than for slope. This study demonstrates the important role of boulders in shaping landscapes.
    Description: Key Points: We develop a theory for steady‐state reach‐scale channel morphology responding to large, rarely mobile boulders in bedrock rivers. Predictions of boulder‐bed channel width and slope are derived based on grade equilibrium and bedrock erosional balance. Theory is tested against new data from the Liwu River, Taiwan, showing steepening and widening with increasing boulder concentration.
    Description: Israel Science Foundation http://dx.doi.org/10.13039/501100003977
    Description: NSF‐BSF
    Description: https://zenodo.org/record/6371224#.YjdBkOpByUk
    Keywords: ddc:551.3 ; boulders ; slope ; width ; bedrock erosion ; sediment transport ; grade
    Language: English
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    Sensitivity of Sea Ice Growth to Snow Properties in Opposing Regions of the Weddell Sea in Late Summer (2022)
    Details
    Publication Date: 2023-01-25
    Description: The sensitivity of sea ice to the contrasting seasonal and perennial snow properties in the southeastern and northwestern Weddell Sea is not yet considered in sea ice model and satellite remote sensing applications. However, the analysis of physical snowpack properties in late summer in recent years reveals a high fraction of melt‐freeze forms resulting in significant higher snow densities in the northwestern than in the eastern Weddell Sea. The resulting lower thermal conductivity of the snowpack, which is only half of what has been previously assumed in models in the eastern Weddell Sea, reduces the sea ice bottom growth by 18 cm during winter. In the northwest, however, the potentially formed snow ice thickness of 22 cm at the snow/ice interface contributes to additional 7 cm of thermodynamic ice growth at the bottom. This sensitivity study emphasizes the enormous impact of unappreciated regional differences in snowpack properties on the thermodynamic ice growth.
    Description: Plain Language Summary: The sea ice cover in the Weddell Sea shows different ice age classes and can therefore be considered as a representative basin of the ice‐covered Southern Ocean: while seasonal sea ice is found in the eastern Weddell Sea, it tends to be perennial in the west. Due to the year‐round Antarctic snow cover, this age classification also applies for the snow column. However, the associated regional differences in snow properties and snow‐to‐ice conversion processes at the snow/ice interface are not yet considered in both sea ice model and satellite remote sensing applications when retrieving, for example, sea ice thickness. Based on recent snow observations in the region, regionally adjusted values for snow density and thermal conductivity could be determined. While the adjusted parameters result in attenuated ice growth in the eastern Weddell Sea, significant snow ice formation causes additional thermodynamic ice growth in the western Weddell Sea.
    Description: Key Points: High fraction of melt‐freeze forms causes significant higher snow densities in the northwestern than in the eastern Weddell Sea. Lower thermal conductivity of snow in the eastern Weddell Sea than previously assumed results in significantly reduced potential bottom sea ice growth. In the northwestern Weddell Sea, the substantial amount of snow ice leads to additional thermodynamic ice growth at the ice bottom.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form
    Description: https://www.meereisportal.de/
    Keywords: ddc:551.34 ; Antarctic ; sea ice ; snow ; ice mass balance ; thermal conductivity ; ice growth
    Language: English
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    High‐resolution XEOL spectroscopy setup at the X‐ray absorption spectroscopy beamline P65 of PETRA III (2022)
    Levcenko, S. ; Biller, R. ; Pfeiffelmann, T. ; [et al.]
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-01-25
    Description: A newly designed setup to perform steady‐state X‐ray excited optical luminescence (XEOL) spectroscopy and simultaneous XEOL and X‐ray absorption spectroscopy characterization at beamline P65 of PETRA III is described. The XEOL setup is equipped with a He‐flow cryostat and state‐of‐the‐art optical detection system, which covers a wide wavelength range of 300–1700 nm with a high spectral resolution of 0.4 nm. To demonstrate the setup functioning, low‐temperature XEOL studies on polycrystalline CuInSe2 thin film, single‐crystalline GaN thin film and single‐crystalline ZnO bulk semiconductor samples are performed.
    Description: X‐ray excited optical luminescence (XEOL) spectroscopy is increasingly important to understand the interplay between the optical properties, structure and chemical composition, providing insights into the mechanism of radiative recombination for a wide range of materials. This study demonstrates a newly implemented setup to perform steady‐state XEOL and simultaneous XEOL and XAFS characterizations at beamline P65 of PETRA III.
    Keywords: ddc:550.2 ; XEOL ; XAS ; CuInSe2 ; ZnO ; GaN
    Language: English
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    Fluorescent colour patterns in the basal pectinid Pleuronectites from the Middle Triassic of Central Europe: origin, fate and taxonomic implications of fluorescence (2022)
    Details
    Publication Date: 2023-01-25
    Description: UV light‐induced fluorescence is widely used as a key to reveal residual shell colour patterns of Neogene and Palaeogene molluscs. However, only few examples of fluorescent colour patterns are known from Mesozoic marine shells and little is known about the nature of fluorescence in fossils. Here, UV light‐induced fluorescence reveals previously unseen abundance and diversity in the colour patterns of the basal pectinid Pleuronectites laevigatus from the Middle Triassic Muschelkalk of Central Europe. In addition to known variations of radial bands, a multitude of zigzag and zigzag‐related patterns was found. The diversity of colour patterns is comparable to modern pectinids and is interpreted as colour pattern polymorphism. Raman spectra of the colour patterns indicated the preservation of residual organic pigments with aromatic moieties. The fluorescence properties of P. laevigatus and other basal pectinids from the Muschelkalk of Germany and France are described in detail, suggesting that colour pattern fluorescence is due to colourless diagenetic products of the pigments, not to the fossil pigments themselves. A remarkable feature of the colour patterns of P. laevigatus is the presence of different fluorescence colours. Because a gradual shift of the fluorescence colour from yellow to red with decreasing intensity to finally non‐fluorescent is observed, which correlates with the provenance of the specimens, the fluorescence properties are interpreted to reflect differences in diagenetic history. The results show that the fluorescence colour of fossil molluscs, especially of Mesozoic molluscs, may be affected by diagenesis and should only be used with caution for taxonomic purposes.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:564.4 ; Bivalvia ; fluorescence ; colour pattern ; preservation ; organic pigment ; Muschelkalk
    Language: English
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    ICON‐O: The Ocean Component of the ICON Earth System Model—Global Simulation Characteristics and Local Telescoping Capability (2022)
    Details
    Publication Date: 2023-01-25
    Description: We describe the ocean general circulation model Icosahedral Nonhydrostatic Weather and Climate Model (ICON‐O) of the Max Planck Institute for Meteorology, which forms the ocean‐sea ice component of the Earth system model ICON‐ESM. ICON‐O relies on innovative structure‐preserving finite volume numerics. We demonstrate the fundamental ability of ICON‐O to simulate key features of global ocean dynamics at both uniform and non‐uniform resolution. Two experiments are analyzed and compared with observations, one with a nearly uniform and eddy‐rich resolution of ∼10 km and another with a telescoping configuration whose resolution varies smoothly from globally ∼80 to ∼10 km in a focal region in the North Atlantic. Our results show first, that ICON‐O on the nearly uniform grid simulates an ocean circulation that compares well with observations and second, that ICON‐O in its telescope configuration is capable of reproducing the dynamics in the focal region over decadal time scales at a fraction of the computational cost of the uniform‐grid simulation. The telescopic technique offers an alternative to the established regionalization approaches. It can be used either to resolve local circulation more accurately or to represent local scales that cannot be simulated globally while remaining within a global modeling framework.
    Description: Plain Language Summary: Icosahedral Nonhydrostatic Weather and Climate Model (ICON‐O) is a global ocean general circulation model that works on unstructured grids. It rests on novel numerical techniques that belong to the class of structure‐preserving finite Volume methods. Unstructured grids allow on the one hand a uniform coverage of the sphere without resolution clustering, and on the other hand they provide the freedom to intentionally cluster grid points in some region of interest. In this work we run ICON‐O on an uniform grid of approximately 10 km resolution and on a grid with four times less degrees of freedom that is stretched such that in the resulting telescoping grid within the North Atlantic the two resolutions are similar, while outside the focal area the grid approaches smoothly ∼80 km resolution. By comparison with observations and reanalysis data we show first, that the simulation on the uniform 10 km grid provides a decent mesoscale eddy rich simulation and second, that the telescoping grid is able to reproduce the mesoscale rich circulation locally in the North Atlantic and on decadal time scales. This telescoping technique of unstructured grids opens new research directions.
    Description: Key Points: We describe Icosahedral Nonhydrostatic Weather and Climate Model (ICON‐O) the ocean component of ICON‐ESM 1.0, based on the ICON modeling framework. ICON‐O is analyzed in a globally mesoscale‐rich simulation and in a telescoping configuration. In telescoping configuration ICON‐O reproduces locally the eddy dynamics with less computational costs than the uniform configuration.
    Description: https://swiftbrowser.dkrz.de/public/dkrz_07387162e5cd4c81b1376bd7c648bb60/kornetal2021
    Description: https://mpimet.mpg.de/en/science/modeling-with-icon/code-availability
    Keywords: ddc:551.46 ; ocean modeling ; ocean dynamics ; unstructured grid modeling ; local refinement ; structure preservation numerics
    Language: English
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    Evidence for Secondary Ice Production in Southern Ocean Maritime Boundary Layer Clouds (2022)
    Details
    Publication Date: 2023-01-25
    Description: Maritime boundary‐layer clouds over the Southern Ocean (SO) have a large shortwave radiative effect. Yet, climate models have difficulties in representing these clouds and, especially, their phase in this observationally sparse region. This study aims to increase the knowledge of SO cloud phase by presenting in‐situ cloud microphysical observations from the Southern Ocean Clouds, Radiation, Aerosol, Transport Experimental Study (SOCRATES). We investigate the occurrence of ice in summertime marine stratocumulus and cumulus clouds in the temperature range between 6 and −25°C. Our observations show that in ice‐containing clouds, maximum ice number concentrations of up to several hundreds per liter were found. The observed ice crystal concentrations were on average one to two orders of magnitude higher than the simultaneously measured ice nucleating particle (INP) concentrations in the temperature range below −10°C and up to five orders of magnitude higher than estimated INP concentrations in the temperature range above −10°C. These results highlight the importance of secondary ice production (SIP) in SO summertime marine boundary‐layer clouds. Evidence for rime splintering was found in the Hallett‐Mossop (HM) temperature range but the exact SIP mechanism active at lower temperatures remains unclear. Finally, instrument simulators were used to assess simulated co‐located cloud ice concentrations and the role of modeled HM rime‐splintering. We found that CAM6 is deficient in simulating number concentrations across the HM temperature range with little sensitivity to the model HM process, which is inconsistent with the aforementioned observational evidence of highly active SIP processes in SO low‐level clouds.
    Description: Plain Language Summary: Clouds in the Southern Ocean are important for climate but not well represented in climate models. Observations in this remote region have been rare. This study presents results from a recent airborne campaign that took place in the Southern Ocean where low‐ and mid‐level clouds were investigated by detecting individual cloud particles within the clouds. Although large fraction of the observed clouds did not contain ice crystals, occasionally high amounts of ice crystals were observed that cannot be explained by ice formation on aerosol particles but were result of multiplication of existing ice crystals. We tested the capability of a commonly used climate model to represent the observed ice concentrations and their sensitivity to one ice multiplication process parameterized in the model. These investigations revealed that the in the model the ice multiplication process was not responsible for generation of ice, which is in contradiction with the observations.
    Description: Key Points: Ice concentrations several orders of magnitude higher than ice nucleating particle concentrations were observed. Secondary ice production was believed to be responsible for the observed high ice number concentrations. Comparison with climate model indicated that secondary ice processes are still inadequately represented in the model.
    Description: National Science Foundation http://dx.doi.org/10.13039/100000001
    Description: U.S. Department of Energy http://dx.doi.org/10.13039/100000015
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: NSF Polar Programs
    Keywords: ddc:551 ; southern ocean ; mixed‐phase clouds ; in‐situ observations ; ice crystals ; secondary ice ; ice nucleating particles
    Language: English
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    Observational Evidence for Multivariate Drought Hazard Amplifications Across Disparate Climate Regimes (2022)
    Details
    Publication Date: 2023-01-25
    Description: Drought poses significant challenges to global water security in a warming world. A global‐scale synthesis of the multivariate drought risk considering interdependencies between drought attributes across disparate climate regimes is still lacking. Leveraging precipitation and streamflow observations of 270 large catchments over the globe, we show that multivariate drought hazard amplifies significantly (at ∼65–76% of catchments) considering dependence between drought duration and severity. A signifying nature of this amplification (A) is the power‐law scaling with dependence metric (A∝τλ;λ=5−12; $A\propto {\tau }^{\lambda };\,\lambda =5-12;$ where τ and λ are Kendall's correlation and the scaling exponent), revealing current approaches considering drought attributes as independent or linearly dependent will severely underestimate likelihood of extreme droughts. Furthermore, we find disparate responses in the multivariate imprints of meteorological to hydrological droughts across climate types, with strengths varying from large to modest in Tropics and Mid‐latitudes, which indicates weaker overlap between rain‐deficit and streamflow droughts. In contrast, a strong overlap in multivariate hazards of rain‐deficit and streamflow droughts is apparent across transitional Subtropics. Our study highlights the relevance of accounting for multivariate aspects of drought hazards to inform adaptation to water scarcity in a changing climate.
    Description: Plain Language Summary: The world's large river basins support a huge population and diverse ecosystems. A growing body of the literature suggests holistic risk management requires a “multivariate event perspective” to analyze interacting drought attributes rather than each of these drivers in isolation. Using the gauge‐based observational framework, we show a robust amplification in multivariate drought hazard and this response co‐vary among distinct climate regimes. Our multivariate hazard framework shows a contrasting response in multivariate imprints (or degree of overlap) of rain‐deficit (drivers) to streamflow (response)‐droughts across disparate climate regimes for milder and extreme categories of droughts; from substantial regional variations in multivariate drought hazard in tropics and mid‐latitudes, revealing a weak imprint between drought types. In contrast, the transitional subtropics show a modest variation in the multivariate imprint of drought types, indicating stronger imprint. We emphasize that failure to account for nonlinear interactions among interacting drought attributes will severely underestimate the extreme drought hazard, jeopardizing the adequacy of resilient water infrastructure design. The insights will aid in adaptation to extreme droughts under global warming.
    Description: Key Points: Global synthesis of multivariate drought imprints between rain‐deficit and streamflow droughts. Observational assessment showed strong amplifications in bivariate drought hazards to dependence. Strong imprints between rain‐deficit and streamflow droughts in transitional sub‐tropics.
    Description: Department of Science and Technology, Ministry of Science and Technology, India http://dx.doi.org/10.13039/501100001409
    Description: German Academic Exchange Service New Delhi http://dx.doi.org/10.13039/501100001650
    Description: Science and Engineering Research Board http://dx.doi.org/10.13039/501100001843
    Description: Indian Institute of Technology Kharagpur http://dx.doi.org/10.13039/501100008984
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: https://portal.grdc.bafg.de/applications/public.html?publicuser=PublicUser
    Description: https://opendata.dwd.de/climate_environment/GPCC/html/download_gate.html
    Keywords: ddc:551.5 ; hydrological drought ; meteorological drought ; multivariate drought hazard
    Language: English
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    From regime‐building to implementation: Harnessing the UN climate conferences to drive climate action (2022)
    John Wiley & Sons, Inc. | Hoboken, USA
    Details
    Publication Date: 2023-01-25
    Description: The gap between the internationally agreed climate objectives and tangible emissions reductions looms large. We explore how the supreme decision‐making body of the United Nations Framework Convention on Climate Change (UNFCCC), the Conference of the Parties (COP), could develop to promote more effective climate policy. We argue that promoting implementation of climate action could benefit from focusing more on individual sectoral systems, particularly for mitigation. We consider five key governance functions of international institutions to discuss how the COP and the sessions it convenes could advance implementation of the Paris Agreement: guidance and signal, rules and standards, transparency and accountability, means of implementation, and knowledge and learning. In addition, we consider the role of the COP and its sessions as mega‐events of global climate policy. We identify opportunities for promoting sectoral climate action across all five governance functions and for both the COP as a formal body and the COP sessions as conducive events. Harnessing these opportunities would require stronger involvement of national ministries in addition to the ministries of foreign affairs and environment that traditionally run the COP process, as well as stronger involvement of non‐Party stakeholders within formal COP processes. This article is categorized under: Policy and Governance 〉 International Policy Framework
    Description: The UN climate conferences can drive implementation across five governance functions, using both their roles as formal decision‐making body and as mega‐events.
    Description: German Federal Ministry for Economic Cooperation and Development (BMZ)
    Keywords: climate regime ; Conference of the Parties ; COP ; UNFCCC
    Language: English
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    Book of Abstracts (2022)
    DMG, DGGV
    Details
    Publication Date: 2023-08-29
    Description: conference
    Keywords: ddc:550 ; GEOMIN ; Deutsche Geologische Gesellschaft – Geologische Vereinigung ; Deutsche Mineralogische Gesellschaft ; Clathrate hydrate
    Language: English
    Type: doc-type:book , publishedVersion
    Format: 440
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    Intrusive Magmatism Strongly Contributed to the Volatile Release Into the Atmosphere of Early Earth (2022)
    Details
    Publication Date: 2023-07-20
    Description: Magmatic volatile release was crucial for the build‐up and composition of the early atmosphere and thus for the origin and evolution of life. Even though the rate of intrusive to extrusive magma production on Earth is high, intrusive volatile release is commonly neglected in studies modeling the composition of the early atmosphere. This can mainly be attributed to the solubility of volatiles like H2O and CO2. The solubility is increasing with depth and thus is thought to prevent the release of these volatiles. However, due to the accumulation of H2O and CO2 within the melt during fractional crystallization, the solubility can be exceeded even at greater depths. In our study, we developed a novel numeric model to quantify the amount of H2O and CO2 that can be released from an intrusive system if we consider the process of fractional crystallization. Additionally, we take the possibility of melt ascent and the formation of hydrous minerals into account. According to our simulations, the release of H2O and CO2 from an intrusive magma body is possible within the whole lithosphere. However, the release strongly depends on the initial volatile budget, the formation of hydrous phases, the depth of the intrusion and the buoyancy of the melt. Considering all these factors, our study suggests that about 0%–85% H2O and 100% CO2 can be released from mafic intrusions. This renders the incorporation of the intrusive volatile release mandatory in order to determine the volatile fluxes and the composition of early Earth's atmosphere.
    Description: Key Points: In our model, we quantify the release of H2O and CO2 from a magma body and its significance for early Earth. We examine the effect of fractional crystallization on the solubility and release of volatiles. We consider the buoyancy of the melt and the formation of hydrous minerals.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://doi.org/10.35003/MDMAJD
    Keywords: ddc:552 ; volatile release ; intrusive magmatism ; fractional crystallization ; early Earth ; atmosphere ; solubility
    Language: English
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    The Interface Between Magma and Earth's Atmosphere (2022)
    Details
    Publication Date: 2023-07-20
    Description: Volatiles released from magma can form bubbles and leave the magma body to eventually mix with atmospheric air. The composition of those volatiles, as derived from measurements made after their emission, is used to draw conclusions on processes in the Earth's interior or their influences on Earth's atmosphere. So far, the discussion of the influence of high‐temperature mixing with atmospheric air (in particular oxygen) on the measured volcanic gas composition is almost exclusively based on thermodynamic equilibrium (TE) considerations. By modeling the combined effects of C‐H‐O‐S reaction kinetics, turbulent mixing, and associated cooling during the first seconds after magmatic gas release into the atmosphere we show that the resulting gas compositions generally do not represent TE states, with individual species (e.g., CO, H2, H2S, OCS, SO3, HO2, H2O2) deviating by orders of magnitude from equilibrium levels. Besides revealing the chemical details of high‐temperature emission processes, our results question common interpretations of volcanic gas studies, particularly affecting the present understanding of auto‐catalytic conversion of volcanic halogen species in the atmosphere and redox state determination from volcanic plume gas measurements.
    Description: Plain Language Summary: A major fraction of magmatic gas emissions are released into the atmosphere from open vents. The emission processes are characterized by fast turbulent mixing with atmospheric air (within seconds) and associated rapid cooling. Hardly anything is known about the chemical kinetics within this brief mixing and cooling period. We simulate the chemical kinetics during the first seconds of hot magmatic gases in the atmosphere and find severe deviation to common interpretations and central thermodynamic equilibrium assumptions prevailing in volcanic gas geochemistry.
    Description: Key Points: We model the chemical kinetics of high‐temperature volcanic gas emissions within the first seconds of mixing with atmospheric air. We identify key chemical processes within the magma‐atmosphere interface and quantify influences on the volcanic plume composition. Our results question common assumptions prevailing in volcanic gas geochemistry and refine interpretations of gas emissions from open vents.
    Description: German Research Foundation
    Keywords: ddc:551.9 ; volcanic gas emissions ; kinetic chemistry modeling ; atmospheric chemistry ; magmatic redox states ; reactive halogen chemistry
    Language: English
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  • 95
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    Atmospheric Contributions to Global Ocean Tides for Satellite Gravimetry (2022)
    Details
    Publication Date: 2023-07-20
    Description: To mitigate temporal aliasing effects in monthly mean global gravity fields from the GRACE and GRACE‐FO satellite tandem missions, both tidal and non‐tidal background models describing high‐frequency mass variability in atmosphere and oceans are needed. To quantify tides in the atmosphere, we exploit the higher spatial (31 km) and temporal (1 hr) resolution provided by the latest atmospheric ECMWF reanalysis, ERA5. The oceanic response to atmospheric tides is subsequently modeled with the general ocean circulation model MPIOM (in a recently revised TP10L40 configuration that includes the feedback of self‐attraction and loading to the momentum equations and has an improved bathymetry around Antarctica) as well as the shallow water model TiME (employing a much higher spatial resolution and more elaborate tidal dissipation than MPIOM). Both ocean models consider jointly the effects of atmospheric pressure variations and surface wind stress. We present the characteristics of 16 waves beating at frequencies in the 1–6 cpd band and find that TiME typically outperforms the corresponding results from MPIOM and also FES2014b as measured from comparisons with tide gauge data. Moreover, we note improvements in GRACE‐FO laser ranging interferometer range‐acceleration pre‐fit residuals when employing the ocean tide solutions from TiME, in particular, for the S1 spectral line with most notable improvements around Australia, India, and the northern part of South America.
    Description: Plain Language Summary: In addition to many rather slow processes such as the melting of glaciers, rapid mass redistribution related to the weather also measurably affect the Earth's gravity field. The ability of monitoring liquid freshwater changes within the Earth system from the satellite gravity missions GRACE (2002–2017) and GRACE‐FO (since 2018) relies on accurate background models of mass variability in atmosphere and oceans for both tidal and non‐tidal processes. Atmospheric tides are primarily excited in the middle atmosphere by solar energy absorption at periods of 24 hr and its overtones. We find additional tidal signatures in the atmosphere excited by periodic deformations of both crust and sea‐surface of the Earth. We thus introduce here a new data set for the atmospheric tides and their corresponding oceanic response that features both more waves and higher accuracy than other background models previously used for the processing of GRACE and GRACE‐FO satellite gravimetry data.
    Description: Key Points: Sixteen relevant tidal lines identified in hourly data from ERA5 atmospheric reanalysis. Dedicated simulations with a high‐resolution global hydrodynamic model to simulate ocean tides with atmospheric influence. New tidal models reduce pre‐fit residuals in GRACE‐FO Laser Ranging Interferometer data.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://pypi.org/project/cdsapi/
    Description: https://mpimet.mpg.de/en/science/models/mpi-esm/mpiom
    Description: https://doi.org/10.5067/graod-1bg06
    Keywords: ddc:526 ; atmospheric tides ; ocean tides ; de‐aliasing ; GRACE‐FO ; ERA5 ; atmospheric forcing
    Language: English
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  • 96
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    Interannual Changes in Tidal Conversion Modulate M2 Amplitudes in the Gulf of Maine (2022)
    Details
    Publication Date: 2023-07-27
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Gulf of Maine's lunar semidiurnal (M〈sub〉2〈/sub〉) ocean tide exhibits spatially coherent amplitude changes of ∼1–3 cm on interannual time scales, though no causative mechanism has been identified. Here we show, using a specially designed numerical modeling framework, that stratification changes account for 32%–48% (Pearson coefficient 0.58–0.69) of the observed M〈sub〉2〈/sub〉 variability at tide gauges from 1994 to 2019. Masking experiments and energy diagnoses reveal that the modeled variability is primarily driven by fluctuations in barotropic‐to‐baroclinic energy conversion on the continental slope south of the gulf's mouth, with a 1‐cm amplitude increase at Boston corresponding to a ∼7% (0.30 GW) drop in the area‐integrated conversion rate. Evidence is given for the same process to have caused the decade‐long M〈sub〉2〈/sub〉 amplitude decrease in the Gulf of Maine beginning in 1980/81. The study has implications for nuisance flooding predictions and space geodetic analyses seeking highest accuracies.〈/p〉
    Description: Plain Language Summary: The height of the twice‐daily tide at Boston is about 135 cm, but researchers have long noted that this value fluctuates by about 1–3 cm from year to year. Here we show that the annual tidal height changes—seen in fact throughout the Gulf of Maine—are closely linked to how seawater density is distributed three‐dimensionally in the region. In particular, as tidal currents enter the gulf over steep underwater topography, the vertical distribution of density determines how much of the incoming wave energy is scattered back as internal tides into the deeper Northwest Atlantic. In years where this conversion of wave energy drops by 7% from its nominal value of 4 Gigawatt, the surface tide at Boston typically increases by 1 cm. Climate‐induced changes in ocean temperature and density may strengthen or weaken the conversion effect and thus slightly alter the role of tides in coastal flood events.〈/p〉
    Description: Key Points〈: We propagate the M〈sub〉2〈/sub〉 tide through realistic, annually varying density structures (1993–2019) in a regional Gulf of Maine model. Stratification changes explain 32%–48% of the observed, cm‐level M〈sub〉2〈/sub〉 amplitude variability at coastal tide gauges from 1994 to 2019. Modeled M〈sub〉2〈/sub〉 changes mainly reflect fluctuations in the barotropic‐baroclinic energy conversion rate on the New England continental slope.
    Description: Austrian Science Fund http://dx.doi.org/10.13039/501100002428
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: https://www.gesla.org/
    Description: https://www.tpxo.net/global/tpxo9-atlas
    Description: https://doi.pangaea.de/10.1594/PANGAEA.856844
    Description: https://marine.copernicus.eu/access-data
    Description: https://www.ncei.noaa.gov/products/northwest-atlantic-regional-climatology
    Keywords: ddc:551.46 ; ocean tides ; tidal conversion ; Gulf of Maine ; nuisance flooding
    Language: English
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  • 97
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    Small‐angle neutron scattering of long‐wavelength magnetic modulations in reduced sample dimensions (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-07-04
    Description: Magnetic small‐angle neutron scattering (SANS) is ideally suited to providing direct reciprocal‐space information on long‐wavelength magnetic modulations, such as helicoids, solitons, merons or skyrmions. SANS of such structures in thin films or micro‐structured bulk materials is strongly limited by the tiny scattering volume vis a vis the prohibitively high background scattering by the substrate and support structures. Considering near‐surface scattering just above the critical angle of reflection, where unwanted signal contributions due to substrate or support structures become very small, it is established that the scattering patterns of the helical, conical, skyrmion lattice and fluctuation‐disordered phases in a polished bulk sample of MnSi are equivalent for conventional transmission and near‐surface SANS geometries. This motivates the prediction of a complete repository of scattering patterns expected for thin films in the near‐surface SANS geometry for each orientation of the magnetic order with respect to the scattering plane.
    Description: Near‐surface SANS is discussed for its potential as a probe of long‐wavelength magnetic modulations in specimens with reduced sample dimensions.
    Keywords: ddc:548 ; small‐angle neutron scattering ; near‐surface SANS ; magnetism ; non‐collinear magnetism ; thin films ; skyrmions ; MnSi
    Language: English
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  • 98
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    Combining reverse Monte Carlo analysis of X‐ray scattering and extended X‐ray absorption fine structure spectra of very small nanoparticles (2022)
    International Union of Crystallography | 5 Abbey Square, Chester, Cheshire CH1 2HU, England
    Details
    Publication Date: 2023-07-21
    Description: Finite size effects in partial pair distribution functions generate artefacts in the scattering structure factor and scattering intensity. It is shown how they can be overcome using a binned version of the Debye scattering equation. Accordingly, reverse Monte Carlo simulations are used for very small nanoparticles of LaFeO3 with diameters below 10 nm to simultaneously analyse X‐ray scattering data and extended X‐ray absorption fine structure spectra at the La K and Fe K edges. The structural information obtained is consistent regarding local structure and long‐range order.
    Description: Computing scattering intensity using the Debye scattering equation after binning interatomic distances avoids finite size artefacts and is efficient enough for simultaneous refinement of scattering data and extended X‐ray absorption spectra by reverse Monte Carlo simulations.
    Keywords: ddc:548 ; extended X‐ray absorption fine structure ; EXAFS ; wide‐angle X‐ray scattering ; WAXS ; reverse Monte Carlo ; RMC ; nanocrystals ; LaFeO3
    Language: English
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  • 99
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    Green batteries for clean skies: Sustainability assessment of lithium‐sulfur all‐solid‐state batteries for electric aircraft (2022)
    Details
    Publication Date: 2023-07-21
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The use of novel battery technologies in short‐haul electric aircraft can support the aviation sector in achieving its goals for a sustainable development. However, the production of the batteries is often associated with adverse environmental and socio‐economic impacts, potentially leading to burden shifting. Therefore, this paper investigates alternative technologies for lithium–sulfur all‐solid‐state batteries (LiS‐ASSBs) in terms of their contribution to the sustainable development goals (SDGs). We propose a new approach that builds on life cycle sustainability assessment and links the relevant impact categories to the related SDGs. The approach is applied to analyze four LiS‐ASSB configurations with different solid electrolytes, designed for maximum specific energy using an electrochemical model. They are compared to a lithium–sulfur battery with a liquid electrolyte as a benchmark. The results of our cradle‐to‐gate analysis reveal that the new LiS‐ASSB technologies generally have a positive contribution to SDG achievement. However, the battery configuration with the best technical characteristics is not the most promising in terms of SDG achievement. Especially variations from the technically optimal cathode thickness can improve the SDG contribution. A sensitivity analysis shows that the results are rather robust against the weighting factors within the SDG quantification method.〈/p〉
    Description: Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy ‐ EXC 2163/1‐ Sustainable and Energy Efficient Aviation
    Keywords: ddc:363.7 ; all‐solid‐state battery ; electric aircraft ; industrial ecology ; life cycle sustainability assessment ; prospective sustainability assessment ; sustainable development goals
    Language: English
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  • 100
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    Modeling cloud properties over the 79 N Glacier (Nioghalvfjerdsfjorden, NE Greenland) for an intense summer melt period in 2019 (2022)
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2023-07-25
    Description: Long believed to be insignificant, melt activity on the Northeast Greenland Ice Stream (NEGIS) has increased in recent years. Summertime Arctic clouds have the potential to strongly affect surface melt processes by regulating the amount of radiation received at the surface. However, the cloud effect over Greenland is spatially and temporally variable and high‐resolution information on the northeast is absent. This study aims at exploring the potential of a high‐resolution configuration of the polar‐optimized Weather Research & Forecasting Model (PWRF) in simulating cloud properties in the area of the Nioghalvfjerdsfjorden Glacier (79 N Glacier). Subsequently, the model simulations are employed to investigate the impact of Arctic clouds on the surface energy budget and on surface melting during the extensive melt event at the end of July 2019. Compared to automatic weather station (AWS) measurements and remote‐sensing data (Sentinel‐2A and the Moderate Resolution Imaging Spectroradiometer, MODIS), PWRF simulates cloud properties with sufficient accuracy. It appears that peak melt was caused by an increase in solar radiation and sensible heat flux (SHF) in response to a blocking anticyclone and foehn winds in the absence of clouds. Cloud warming over high‐albedo surfaces helped to precondition the surface and prolonged the melting as the anticyclone abated. The results are sensitive to the surface albedo and suggest spatiotemporal differences in the cloud effect as snow and ice properties change over the course of the melting season. This demonstrates the importance of including high‐resolution information on clouds in analyses of ice sheet dynamics.
    Description: German Federal Ministry for Education and Research http://dx.doi.org/10.13039/501100002347
    Description: https://doi.org/10.5065/EM0T-1D34
    Description: https://cds.climate.copernicus.eu/cdsapp/#!/search?type=dataset
    Description: https://ladsweb.modaps.eosdis.nasa.gov/search/
    Keywords: ddc:551.5 ; cloud properties ; cloud radiative effect ; Northeast Greenland Ice Stream ; regional climate modeling ; surface energy balance ; surface melt ; surface energy balance ; surface melt
    Language: English
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