bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulence evolution of coronal hole solar wind in the inner heliosphere: Solar Orbiter and Parker Solar Probe combined observations
Authors: Perrone Denise
Published: February 2023

Turbulence in plasmas involves a complex cross-scale coupling of fields and distortions of particle velocity distributions, with the generation of non-thermal features. How the energy contained in the large-scale fluctuations cascades all the way down to the kinetic scales, and how such turbulence interacts with particles, remains one of the major unsolved problems in plasma physics. Moreover, solar wind turbulence is not homogeneous but is highly space-localized and the degree of non-homogeneity increases as the spatial/time scales decrease (intermittency). Such an intermittent nature has also been found to evolve with distance from the Sun, possible due to the emergence of strong non-homogeneities over a broad range of scales.Here, by means of new measurements by both Solar Orbiter and Parker Solar Probe, the radial evolution of a homogeneous recurrent fast wind, coming from the same source on the Sun (namely a coronal hole), has been studied from global properties and large-scale features to kinetic structures as it expands in the inner heliosphere from 0.1 out to 1 AU [Perrone et al., 2022]. In particular, the nature of the turbulent magnetic fluctuations around ion scales during the expansion of the wind, has been investigated and the observed coherent events both close to the Sun and to the Earth are statistically studied. The ion scales appear to be characterized by the presence of non-compressive coherent structures, such as current sheets, vortex-like structures, and wave packets identified as ion cyclotron modes, responsible for solar wind intermittency and strongly related to the energy dissipation. Particle energization, temperature anisotropy, and strong deviation from Maxwellian, have been observed in and near coherent structures, both in in-situ data and numerical simulations. Understanding the physical mechanisms that produce coherent structures and how they contribute to dissipation in collisionless plasma will provide key insights into the general problem of solar wind heating. Perrone, D., et al. (2022) Astronomy & Astrophysics (Special Issue: Solar Orbiter First Results – Nominal Mission Phase) 668, A189
Experimental data on REE in apatite in high-REE environments: distinguishing magmatic and metasomatic compositions
Authors: Zhukova Irina , Stepanov Aleksandr
Published: February 2023

Apatite with high REE content is common in alkaline rocks, carbonatites and products of hydrothermal processes. The REE concentrations could enter mineral structure by different substitution mechanisms (Fleet et al., 2000) and the factors controlling the composition of high-REE apatite are not completely understood. New experimental data (Stepanov et al., 2023) show that at 800 °C and 10 kbar apatite crystalizing from felsic melt with addition of NaCl contains 14 wt.% ΣREEOx and coexists with britholite (37.2 wt.% ΣREEOx). The results suggest that equilibrium has been established during the run and both apatite and britholite contained REE in [Si4+REE3+] to [Ca2+P5+] solid solution, whereas the coupled substitution [Na1+REE3+] to [2Ca2+] was insignificant despite crystallisation from an alkaline, Na-rich melt. Coupling of the new experimental data allowed to constrain the width of the miscibility gap between apatite and britholite, and suggest complete miscibility between apatite and britholite above 950 °C. The substitution [Na1+REE3+] apparently develops mainly in apatite replacement reactions. Therefore, REE content and substitution mechanisms could be useful tools for interpretation of magmatic and metasomatic/hydrothermal associations in alkaline volcanic and plutonic rocks.References Fleet, M., Liu, X., Pan, Y., 2000. Rare-earth elements in chlorapatite [Ca-10(PO4)(6)Cl-2]: Uptake, site preference, and degradation of monoclinic structure. American Mineralogist 85, 1437–1446.Stepanov, A.S., Zhukova, I.A., Jiang, S.-Y., 2023. Experimental constraints on miscibility gap and partitioning between britholite and chlorapatite in alkaline melt. American Mineralogist.
Highlights on periphyton in a recently deglaciated floodplain
Authors: Roncoroni Matteo , Mancini Davide , Ballu Aurélien , Miesen Floreana , Müller Tom , Gianini Mattia , Ouvry Boris , Clémençon Mélanie , Selitaj Adrijan , Lardet Frédéric , Battin Tom , Lane Stuart Nicholas
Published: February 2023

Glaciers are retreating worldwide due to climate change, creating extensive proglacial margins exposed to solar radiation and hence colonization by phototrophic organisms. The extremely dynamic nature of proglacial margins makes ecological colonization difficult. Whilst proglacial margins have received significant attention from the geomorphology community, their ecological functioning remains less intensively investigated. Classic research has shown that colonization depends on distance from the glacier terminus and on season. However, with current rates of glacier retreat, long downstream distances are becoming exposed in a relatively short time, questioning the validity of this longitudinal chronosequence model. In this research, we decrypt the physical habitat of periphyton in recently deglaciated floodplains and we demonstrate the role that periphyton plays in favoring embryonic ecosystem development. First, we combine UAV based remote sensing with characterization of local environmental conditions (e.g., inundation extent, rates of disturbance). We show that in proglacial margins periphyton effectively develop extensively during windows of opportunity (i.e., spring and autumn) but they can also develop less extensive but still important extents in summer, during the season of most intense glacial melt. Such development may occur rapidly (timescale of days) in the active zone of the braidplain as access to water is secured. But high rates of morphodynamic reworking means that the periphyton are emphemeral. However, in smaller channels, often fed by hillslope tributaries and/or groundwater, away from the active zone, that are more stable, extensive perennial periphyton cover may develop. As the probability of access to water tends to be positively correlated with the probability of disturbance, extensive perennial periphyton development is spatially restricted. Second, we deploy in-situ flume experiments to mimic the conditions of stable channels and use close-range photogrammetry and 3D hydraulic analysis. We show that periphyton development strongly modifies the streambed morphology but much less so the near-bed hydraulics. Most importantly, it reduces water vertical infiltration by clogging the streambed interstices. This autogenic response, a form of ecosystem engineering, explains why pioneer vegetation tends to develop in specific locations of a glacial floodplain, and reveals new patterns in primary succession in deglaciated terrains and the important role played by periphyton. However, whilst periphyton can improve local hydrological conditions, they do not appear to be able to counter the potential risks of geomorphic disturbance and it is that which determines the patterns of ecological succession.
How fitting are open-source flood models in capturing flood risks over mountainous regions: A prudent analysis over Chamkar Chu Basin, Bhutan using HEC-RAS v6.3
Authors: Namgyal Trashi , Mohanty Mohit Prakash , Thakur Dev Anand
Published: February 2023

On a global scale, the frequency and magnitude of flooding are getting worse. Although hydrologists around the globe have developed sophisticated flood models, their performance, especially over mountainous regions, is not comprehensively understood. The situation is challenging for flood-affected low-income nations, as sufficient resources are needed to procure commercial flood models with appropriate technical know-how. For instance, Bhutan, a mountain-dominated landscape in Asia, has been experiencing unprecedented flooding due to its fragile topography and climate change impacts. Unfortunately, a comprehensive data-driven modeling approach to determining flood hazard zones is missing in this region. The present study quantifies flood risks while considering a robust hydrodynamic flood model over Bhutan’s Chamkhar Chu River basin, a severely flood-prone area. The recently released open-source HEC-RAS v6.3 by the U.S. Army corps of Engineers, whose efficacy for flood inundation modeling is less explored, is considered to derive a set of flood risk maps. The coupled 1D-2D flood model setup is developed to simulate various flooding scenarios corresponding to design discharge and rainfalls for 50-yr, 100-yr, and 200-yrs. A corrected high-resolution Digital Elevation Model (DEM) from the ALOS-PALSAR product was utilized to reduce uncertainties in the final flood risk values. The simulated flood hazard maps for the settlements along the Chamkhar chu river are quantified in terms of flood depth, velocity, and a product of depth and velocity. A set of performance statistics are derived from testing the model performance while comparing the simulated inundation maps with the past inundation maps from MODIS satellite imagery. It was noticed that a significant portion of the central region is at a potential threat of very high flood risk as the simulated depth exceeds 3 m and velocities surpassing over 1.6 m/s. Such research will assist flood management agencies in prioritizing affordable structural and non-structural flood mitigation measures for the public that will reduce the impact of flood hazards in the future. Given the efficient computational performance of HEC-RAS v6.3 over a sensitive terrain, the study encourages the adoption of the model for accurately identifying flood risks over global mountainous regions for effective flood management.
New Insights into Underlying Mechanisms of CO2 Wettability and Residual Saturation from Laboratory Measurements of Multi-Phase Zeta Potential in Supercritical CO2-Rock-Brine Systems
Authors: Hidayat Miftah , Vinogradov Jan , Sarmadivaleh Mohammad , Iglauer Stefan , Vega-Maza David , Derksen Jos
Published: February 2023

Measurements of the zeta potential using streaming potential method are frequently used to characterise flows in subsurface settings owing to a broad range of applications of this petrophysical property; examples include CO2 geological storage, hydrocarbon reservoirs, geothermal sources and freshwater aquifers. Many experimental studies of the zeta potential have been carried out covering a wide range of parameters including different rock mineralogy, brine concentration and composition, and temperature to understand the impact of each parameter. The capability of the streaming potential method to be used on intact rock samples, single-/ and multi-phase flows, wide range of salinity, pressure and temperature makes the method suitable for representation of typical subsurface conditions. However, none of previous studies reported high multi-phase measurements at high pressure conditions typical for deep reservoirs. To adequately represent subsurface conditions of carbon geological storage sites, the minimum experimental pressure of 7.38 MPa and minimum temperature of 31 °C, consistent with the supercritical-CO2 (scCO2), need to be used. Obtaining stable measurements of the streaming potential under these conditions is extremely challenging. We report a detailed design of a high-pressure experimental system and experimental protocol for multi-phase streaming potential measurements that were carried out on scCO2-sandstone-brine systems at temperature of 40 °C, pressures ≤10 MPa and with a variety of aqueous solutions.The obtained results demonstrate for the first time that the multi-phase zeta potential correlates with the measured scCO2 residual saturation and rock’s wetting state interpreted from other parameters. Moreover, our results unambiguously identify for the first time the polarity and likely magnitude of the scCO2-brine interfacial zeta potential. Our findings improve the current understanding of the complex wetting behaviour of scCO2 and provide important experimental data for numerical (surface complexation, molecular dynamics), analytical (DLVO) or combined models.
Present and future evolution of the winter snow cover in the French Vosges massif with the help of the regional climate MAR model
Authors: Fettweis Xavier , Ghilain Nicolas , Ambroise Bruno , David Pierre-Marie , Paul Patrice , Wuest Cyril
Published: February 2023

The regional climate MAR model is widely used in polar regions where its outputs are often recognised as reference to study the evolution of the surface mass balance over both poles. Here, we have applied with success MAR (version 3.13) at a spatial resolution of 4km to study the snow cover evolution in winter (Dec-Jan-Fev) over the Vosges massif (N-E of France) where there are still some ski resorts. To best compare with in situ daily observations of snow height available in this area, the only two parameters we needed to change in the MAR snow module are the fresh snowfall density (fixed to 100 kg/m3 here instead of a wind speed-temperature dependant fresh snow density) and the snow-rain air temperature limit (fixed to +1°C instead of -1°C for polar regions). Over current climate when MAR is forced by the reanalysis ERA5 from 1950, MAR suggests already a decrease by a factor two of both the snow cover and the mean snow height over 1960-2022 as a result of increasing temperatures and increasing precipitation falling as rainfall instead of snowfall. The 1960-2022 warming simulated by MAR is mainly the result of increasing longwave radiation and is the highest in the Rhine Valley due to more frequent South-West circulation favouring foehn effects and then enhancing the temperature increase. Finally, MAR has been forced by two global models MPI-ESM1-2-HR and MIROC6 (from the CMIP6 data base) using the SSP585 scenario to study the snow cover evolution and its quasi disappearance in the low altitude areas in the next decades.

 
Exploring nature-based solutions to droughts and floods in the Limpopo basin
Authors: Van Loon Anne , Matanó Alessia , Tirivarombo Sithabile , Artur Luis , Mustafa Syed , Rohse Melanie , Day Rosie , Comte Jean-Christophe
Published: February 2023

Southern Africa faces both severe droughts and strong floods. Communities describe how they are impacted by both extremes, but do not regard them as connected. They prepare for droughts by implementing water-saving measures and crop changes, but report doing little to prepare for floods. Governance actors instead try to manage both extremes, for example by installing dams that can capture floodwater to increase water availability during dry seasons. In the Connect4WR project, we combined community and governance interviews and workshops with scenario modelling to explore more nature-based solutions focusing on subsurface storage and infiltration. The governance actors in the four countries of the Limpopo (Botswana, Zimbabwe, South Africa and Mozambique) were keen to explore effects of afforestation, sand dams, managed aquifer recharge, and rainwater harvesting. The coupled surface-water-groundwater model we set up, showed that these measures can successfully reduce both droughts and floods. Especially measures that increase groundwater levels both increase water availability and reduce flood peaks throughout the basin. Although downstream communities benefit from the decreased flooding, they could be negatively affected if measures that increase (ground)water storage are combined with high abstraction for irrigation in the upstream part of the basin. In a transboundary river basin like Limpopo, international cooperation and information sharing is crucial. Also, these measures are often too costly and large-scale for the resource-limited rural communities, who can often only respond to extremes by relocating to less drought- or flood-prone areas. Training and government support can help with the implementation of nature-based solutions, but measures need to be resonating with local cultural practices to be adopted and effective land- and water management is important. In this presentation I will discuss the benefits and challenges related to the implementation of nature-based solutions in low- and middle-income countries with fragile populations.
Moisture transport into the Arctic in a past and future climate
Authors: Eckhardt Sabine , Svendby Tove , Steensen Birthe , Myhre Gunnar , Germundsen Ada , Olivie Dirk
Published: February 2023

The Arctic is warming at a faster rate than the rest of the globe. There are both remote and local mechanism identified driving this process. While albedo changes and atmospheric stability happens within in the Arctic, transfer transport processes, both in the ocean and atmosphere, heat and moisture into the Arctic. These processes can be analysed in a Eulerien way, by observing the fluxes through a curtain defining the Arctic or/and by Lagrangian analysis which follows this transport processes all the way from uptake in the mid/high latitudes until the inflow into the Arctic. We use a Lagrangian Particle Transport model FLEXPART running with ECMWF reanalysis data as well as with data from the norwegian earth system model NorESM, which represents the future climate scenarios until 2100. In this way we investigate the inflow of moisture and energy for the last 50 years, but can also project it in the future by considering the climate model output.We find that the the transport through the 65N Latitude, defining the Arctic area is highly inhomogenious in space, but has also a distinct seasonal variability. The end of the storm tracks, especially the Northern Atlantic stormtrack show the most important region of inflow. While moisture origins over ocean areas in winter, continental areas in summer act as a source. The patterns in the reanalysis data from ECMWF and in the climate simulations are very similar. Those patterns are stable over time, but intensify in a warming climate.
A study on the diurnal variation of the snowfall structure in the western coastal region of the Korean Peninsula.
Authors: Yoo Soojin , Chang Eun-Chul , Lee GyuWon
Published: February 2023

 On the western coastal region of the Korean Peninsula in the winter, heavy snowfall occurs due to air mass modification which is called the western coast snowfall. The western coast snowfall occurs through a mechanism similar to the lake effect snowfall that is formed over the Great Lakes in the North America. In the winter season, cold and dry northwesterly wind blowing from the south-eastern flank of the Siberian High is formed over the Yellow Sea. The cold and dry air mass from the continent gets heat and moisture from the ocean when it passes over the relatively warm sea surface, , which invigorate snow clouds. The snow clouds generated over the ocean flow into the western coastal region by the westerly winds, hence predicting when the snow clouds flow into the land is important for snowfall forecast. Although the western coast snowfall can persist for several days when the synoptic environment is maintained, diurnal fluctuations in snowfall inflow appears during the snowfall cases. In this study, the diurnal variation of snowfall inflow on the western coastal region was investigated by analyzing of the dynamic/thermodynamic factors affecting the diurnal variation. The western coast snowfall shows snowfall inflow into the land in the evening, then inflow decreases after sunrise, with the snowfall becoming concentrated over the ocean, and the snowfall inflow increases after sunset. The diurnal variation of the snowfall inflow structure appears with the diurnal variation of the dynamic/thermodynamic structure according to the solar radiation diurnal cycle. During the evening, as the temperature of the lower troposphere over the land decreases due to radiative cooling, the lower troposphere thermal stability increases. After sunrise, the planetary boundary layer (PBL) height grows due to radiative heating, and the wind in the lower troposphere weakens, limiting the snowfall inflow to 9 LST, where both factors affect simultaneously. In addition, as the lower troposphere temperature over the land decreases, the land-sea horizontal temperature contrast increases, and the density wall of the colder land blocks the inflow of the snowfall. On the other hand, during the daytime, the lower troposphere temperature of the land rises due to radiative heating and the thermal stability decreases. As the horizontal temperature contrast decreases and the PBL height decreases after sunset, the lower troposphere wind becomes stronger, which allows the snowfall penetrates into the land. According to the time lag in heating/cooling by radiation of the lower troposphere, it is analyzed that the time point of snowfall inflow interruption (increasing) appears after sunrise (sunset). AcknowledgementThis work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government(MSIT) (No. 2021R1A4A1032646).
“HespDiv” method allows to quantify the dark matter of biosystems
Authors: Daumantas Liudas , Spiridonov Andrej
Published: February 2023

Bretskyan hierarchy of eco-evolutionary entities is a useful theoretical concept that defines hierarchies of communities of species which reside in the same geographical space and are tied together by ecological interactions and evolutionary history. Bretskyan hierarchy can be employed to define and track the evolving hierarchy of bioregions, allowing all sorts of (paleo)biogeographical investigations to be carried out: from finding the causes why bioregions split or fuse and how this happens at many spatial scales, ie. what drives the internal structure of bioregions in Bretskyan hierarchy. Unfortunately, methodical applications of this concept are challenging due to the hybrid nature of Bretskyan hierarchy entities and fuzziness of their boundaries.In order to help solve the presented problem of explicit subdivision of contiguous spatial regions, which are in our understanding the units of the Bretskyan hierarchy, we propose a new method, within the newly developed R package “HespDiv” which presents a range of functionalities for the determination of spatial structures/bioregions. The method uses fossil taxa distribution data to subdivide a provided territory into hierarchically related (each bioregion is a strict sub-set of larger bioregion) and topologically contiguous bioregional units. It produces split-lines which are used to subdivide bioregions. This subdivision can be done by employing linear or nonlinear divisor lines inside predetermined area polygons. In a latter case, the inferred bioregions can obtain more realistic shapes. The application of “HespDiv” method to Miocene fauna from the contiguous United States was performed in order to demonstrate the potential of the method. Morisita-Horn similarity index was used to measure differences between fossil taxa communities. The results revealed 25 distinct, topologically contiguous and hierarchically related bioregions had the structure dominated by longitudinal and diagonal boundaries, and the three most distinct bioregions were: West Coast, Central Plains and south-east US. The numerical analyses of real world paleobiogeographical data with newly developed “HespDiv” method indeed show a high potential of the approach in objectively defining the hierarchical units of the Bretskyan hierarchy of (paleo)bioregions in sufficiently densely sampled regions and time bins.                      Presented research is funded by project S-MIP-21-9 “The role of spatial structuring in major transitions in macroevolution”.
Comprehensive measurements of speciated reactive nitrogen NOy and non-methane volatile organic compounds in Tokyo
Authors: Inomata Satoshi , Tanimoto Hiroshi , Matsumoto Jun , Sadanaga Yasuhiro , Kato Shungo
Published: February 2023

In Japan, concentrations of precursors of photochemical oxidants such as nitrogen oxides (NOx) and non-methane hydrocarbons (NMHCs) are decreasing year by year, but an improvement regarding photochemical oxidants is recently stagnant. To elucidate the reason, we have planned seasonal intensive observations in Tokyo, in which comprehensive measurements of speciated reactive nitrogen NOy and non-methane volatile organic compounds are performed. In summer of 2022, the observation was carried out at a campus of Tokyo Metropolitan University, a suburban area of Tokyo. In the intensive observation, NO, NO2, ΣPANs, ΣONs, HONO, HNO3, H2O2, SO2, O3, NH3, 28 NMHCs, and 10 oxygenated volatile organic compounds (OVOCs) were measured simultaneously. The ΣPANs and ΣONs were measured by thermal dissociation-cavity attenuated phase shift (CAPS) spectroscopy. The HONO, HNO3, and H2O2 were measured by negative ion chemical ionization mass spectrometry using I−·(H2O)n as the reagent ion. The NMHCs, OVOCs and NH3 were measured by selected ion flow tube mass spectrometry and the data of NMHCs were compared and corrected with the data from gas chromatography/flame ionization detector (GC/FID). The ozone formation in Tokyo will be discussed.
Terrestrial cosmogenic nuclides in Danube sediments record vertical movement in a transect from the Eastern Alpine Foreland into the Vienna Basin (Austria)
Authors: Neuhuber Stephanie , Ruszkiczay-Rüdiger Zsófia , Braucher Régis , Salcher Bernhard , Hintersberger Esther , Thöny Wolfgang , Strauss Philipp , Grupe Sabine , Payer Thomas , Braumann Sandra , Lüthgens Christopher , Fiebig Markus
Published: February 2023

Quaternary landscape evolution in the Vienna Basin and the adjacent area west of its subsiding area is controlled by sediment redeposition, aggradation and erosion of the Danube, local normal faulting, and overall regional uplift. Glacial - interglacial climate dynamics highly influence the hydrodynamics and amount of sediment transport. Over the last 9 years sediments exposed during construction and drilling as well as from surface outcrops were sampled for cosmogenic nuclide age determination and uplift/incision rate calculation.The Vienna Gate marks the transition of the Danube alluvial plain in the west (Tullnerfeld) into the extensional structure of the Vienna Basin. At this border, the Danube flows on top of an approximately 2 km wide segment of Penninic Flysch units before it enters the Vienna Basin to the east. Within the transtensional structure of the Vienna Basin, several fault blocks record local uplift and subsidence. Outside of the Vienna Basin, regional uplift is documented by fluvial terrace deposits at elevated positions located at different heights above the recent Danube riverbed.The current status and tectonic context of numerical ages ranging between 250 kyr and 3 Ma will be presented in detail at the conference. Few locations appear to be sedimentologically unsuitable for cosmogenic nuclide burial age dating, those scenarios will be explored and discussed. Funding: HJS 318325/2018; OMAA 90ou17; OMAA 98ou17; NKFIH FK124807
years of seismicity on the Reykjanes Peninsula, SW Iceland
Authors: Doubravová Jana , Magnússon Rögnvaldur Líndal , Konrádová Diana , Horálek Josef , Fischer Tomáš , Águstsdóttir Thorbjörg , Gudnasson Egill Árni
Published: February 2023

Reykjanes Peninsula (SW Iceland) is an extraordinary place from the geophysical perspective. Lying on the on-shore part of the Mid-Atlantic Ridge, interlaced by volcanic systems and hosting several high temperature geothermal areas, the seismic activity on the Peninsula is generally persistent on a microseismic level, but occasionally reaching up to ML~5-6. Throughout the years, many temporary seismic stations or small to medium size local seismic networks have been deployed there for various purposes, from geothermal prospection monitoring to short time passive seismic experiments. We analyzed 10 years of natural seismicity recorded by the semi-permanent local seismic network REYKJANET (in operation since 2013) together with several permanent stations of the SIL regional seismic network present in the area of interest, in total number of 22 stations covering an area of about 1200 km2. The timespan, 2013-2022, contains times of relative quiescence, several small tectonic earthquake swarms as well as very active periods of volcano-tectonic origin, with dyke intrusions and larger earthquakes of magnitudes up to ML- 5.4. We study the distribution of epicenters of the background seismicity as well as for the several seismically active periods with a consistent set of stations.We compare several different automatically derived earthquake catalogues using different detection and location algorithms, and their common features such as the upper and lower limit of the epicenter occurrence, seismogenic faults, aseismic zones and void areas. The dataset contains dyke intrusions related events during the the 2021-2022 Fagradalsfjall volcano-tectonic event.Depending on the exact quality criteria and method used, we deal with over 100,000 events with high quality stable locations imaging the subsurface beneath the Reykjanes Peninsula.
Sedimentology and sequence stratigraphy of the lower Aalenian Opalinuston Formation from southern Germany
Authors: Erbacher Jochen , Mann Thomas , Bornemann André
Published: February 2023

Aalenian sedimentary deposits in southern Germany have accumulated in a shallow-marine, epicontinental shelf environment. These accumulations are dominated by thick claystones and argillaceous siltstones, with increasing percentages of sandstones towards the top. Aalenian sediments are likely to represent a relatively complete stratigraphic record, however, the sedimentary evolution and paleoclimatic significance of these typically poorly exposed deposits remain largely unexplored. Here we present a suite of high-resolution x-ray fluorescence (XRF) core scanning data from southern Germany to identify Transgressive-Regressive cycles during the Aalenian stage. Results are based on three scientific drill cores of 200 – 250 m length that have been analyzed with an Avaatech XRF Core Scanner at a 10 mm sampling interval (10 keV, 500 µA). Resulting trends in elemental Si/Al ratios, which are indicative for subtle grain-size variations, combined with sedimentological observations on ichnofacies and bedform development were used to reconstruct shoreline trajectories and establish a sequence stratigraphic framework for the thick and largely homogenous lower Aalenian Opalinuston Formation.
Divergence of the gradient, solution domain geometry and successive approximations in gravity field studies
Authors: Holota Petr
Published: February 2023

The structure of the Laplace operator is relatively simple when expressed in terms of spherical or ellipsoidal coordinates. The physical surface of the Earth, however, substantially differs from a sphere or an oblate ellipsoid of revolution, even if optimally fitted. The same holds true for the solution domain and the exterior of a sphere or of an oblate ellipsoid of revolution. The situation is more convenient in a system of general curvilinear coordinates such that the physical surface of the Earth (smoothed to a certain degree) is imbedded in the family of coordinate surfaces. Therefore, a transformation of coordinates is applied in treating the geodetic boundary value problem. The transformation contains also an attenuation function. Subsequently, tensor calculus is used and the Laplace operator is expressed in the new coordinates. Its structure becomes more complicated now. Nevertheless, in a sense it represents the topography of the physical surface of the Earth. For this reason the Green’s function method is used together with the method of successive approximations in the solution of the geodetic boundary value problem expressed in terms of the new coordinates. The structure of iteration steps is analyzed and if possible, it is modified by means of integration by parts. The iteration steps and their convergence are discussed and interpreted. The approach is also compared with the method of analytical continuation.
Deterministic Seismic Hazard Assessment by revisiting 1991 Uttarkashi and 1999 Chamoli Earthquake for Uttarakhand, India
Authors: Sharma Yaggesh , Srivastava Mudit , Sharma Priyanka , Kumar Deepak
Published: February 2023

Deterministic Seismic Hazard Assessment is a quantitative site-specific evaluation of ground response for a particular region. Destructive effects caused due to occurrence of natural seismic hazards can be minimized by accounting mindful mitigation measures. One of the fundamental phases in risk assessment is the précised determination of the risk over a certain period. Considering the earthquake rupture model and a couple of defined region-specific ground motion models as input, earthquake scenarios to determine peak ground acceleration (PGA) and spectral periods (SA) are examined. In the present study, the Topographic slope as a proxy for shear wave velocity in upper soil of 30-meter (Vs30) estimation is assessed for rapid prediction and first-order studies. Further, two distinct major earthquake scenarios, the 1991 Uttarkashi and 1999 Chamoli earthquakes are revisited to estimate the distribution of PGA and SA at 0.2 sec and 1 sec for the area of interest. Thus, obtained results for Uttarakhand are presented in terms of Vs30, PGA, 0.2 sec, and 1-sec spectral values respectively.Keywords: Deterministic seismic hazard, Vs30, 1991 Uttarkashi, 1999 Chamoli, scenario earthquakes, PGA, SA.
Natural versus anthropogenic erosion in Central Brazil, a confrontation of time and space scales
Authors: Siame Lionel Louis , Espíndola Rosa Lucas , Cherem Soares Luis Felipe , de Oliveira José Guilherme , Evrard Olivier , Barhoumi Houda , Leanni Laëtitia , Duvivier Adrien , Blard Pierre-Henry , Bourlès Didier , Cornu Sophie
Published: February 2023

Land degradation resulting from increased continental surface erosion is a worldwide and systemic phenomenon due to human activities. Already fragile, the intertropical zone is likely to be further affected by climate change and increased aridity, an aggravating factor of soil erosion and land degradation. A major challenge is thus to provide the necessary knowledge to not only deepen our understanding of the Earth system and its critical thresholds but also to help achieving sustainable development goals. Understanding the factors that control the properties and processes of the critical zone, and especially what will be its responses to ongoing climate and land use changes, requires multidisciplinary efforts to tackle time scales that are compatible with morphogenesis and soil development as well as environmental disturbances of anthropogenic origin. Due to its prominent ecological importance, the Brazilian Cerrado biome is an ideal natural laboratory were to gauge the consequences of recent and strong human activities on continental surface erosion. We focused on the region of Brasília where our approach allows confronting the temporal scales of long-lived and stable cosmogenic nuclides with that of short-lived radioactive isotopes, through a comparison of natural and anthropogenically disturbed land surfaces. Our results indicate that long-term, background denudation rates are lower than 10 mm kyr-1whereas recent erosion rates due to human activities may reach rates at least 160 times higher, exceeding by far the sustainability rates of the soil resource.
On learning discretization schemes of partial differential equations in geoscience
Authors: Ishikawa Tatsuya
Published: February 2023

Solving partial differential equations (PDEs) stably and accurately is essential in simulation analysis of a variety of geophysical phenomena. Designing appropriate discretization schemes for PDEs requires careful and rigorous mathematical treatment and has been a long-term research topic. The computational efficiency is additionally a long-standing challenge when what-if hazard scenario analysis is considered. The data-driven discretization is a hybrid approach to combine machine learning and physics-based simulations, which provides a methodology to derive better discretization schemes from reliable references obtained typically using known stable schemes with higher resolution grids. As the resultant schemes may inherit the physics described by the PDEs, surrogate models employing them are expected to be in good agreement with expensive simulations. It is also argued that the learnt schemes by neural network models can exhibit similar characteristics to known sophisticated algorithms and outperform them in terms of accuracy. However, the method has currently been assessed with only limited examples and the detailed mechanisms of the learnt schemes are not well understood. In this presentation, thorough assessment and investigation of learning discretization schemes are conducted by applying the methodology to several types of differential equations with different learning models for the schemes. Whether the methodology has the potential to derive new schemes is also discussed.
Locally recycled late Pleistocene loess feeds modern dust storms at the desert margins of the eastern Mediterranean, Israel
Authors: Crouvi Onn , Shalom Ohad , Enzel Yehouda , Rosenfeld Daniel
Published: February 2023

Current dust storms, originating from afar, are common in Israel and the eastern Mediterranean, and thus most dust sources are considered to be distal. However, recent studies suggest that the latest Quaternary loess accreted in the Northern Negev can also serve as a proximal source of dust. These sources were mostly neglected in past discussions as contributors of dust. Here, we demonstrate that such proximal dust sources, mostly the Negev loess, currently contribute relatively large amounts of recycled dust to the regional dust cycle. We conducted a sampling campaign of deposited dust during individual dust storms and identified high content of coarse silt grains and quartzo-feldspathic minerals within and adjacent to the Negev loess that gradually decreases toward the north. These grains, characteristics of the Negev loess, indicate a short transport distance. In addition, our data reveal that local wind speed is the limiting factor for emitting proximal dust, regardless of the synoptic system. We determined that proximal sources in Israel emit dust during either local events or as a part of regional dust storms originating from afar. We evaluate the minimal contribution of this proximal dust to the total mass of deposited dust as 58–74%, 54–70%, 52–64%, and 26–34% for the northern Negev, central Negev, central mountainous region, and northern Israel, respectively. These estimates indicate that at the desert fringe, both proximal and distal sources of dust should be considered when inferring dust sources from dust geochemistry that can sometimes be similar due to the long dust history.
Emissions of NMVOC from field application of manure measured by PTR-MS
Authors: Feilberg Anders , Lemes Yolanda Maria , Kamp Jesper Nørlem , Pedersen Johanna
Published: February 2023

Non-methane volatile organic compounds are important air pollutants that contribute to tropospheric ozone production in combination with nitrogen oxides (NOx) and sunlight. Ozone is an important but often overlooked greenhouse gas with adverse effects on human health and crop yields as well as climate. Due to these indirect effects, there is a need for knowledge on emissions and potential mitigation strategies for NMVOC from key sources. Agricultural activities have recently been assessed to be a major source of non-methane volatile organic compounds (NMVOC) with particular importance in regions with intensive livestock production and manure management. In e.g. Denmark, recent assessments indicate that agriculture is the dominant source of NMVOC exceeding emissions from industry, transportation and residential heating. However, estimates of NMVOC emissions from agriculture are based on very limited realistic data and obtained by e.g. indirect calculations relative to ammonia. According to estimates for 2020 (EMEP Centre on Emission Inventories and Projections), around 25% of NMVOC in EU are from agriculture with livestock production and manure management being the dominant sources. These emission inventories are, however, quite uncertain and only based on measured data to a very low degree. Only very few studies have actually attempted to quantitatively measure NMVOC emissions from agricultural facilities and activities. In addition, little is known about the NMVOC composition and how composition varies with sources and conditions. Here, data on emissions from field application of manure based on a number of wind tunnel experiments are presented and used to estimate the contribution to national NMVOC emissions. NMVOC were quantified by proton-transfer-reaction mass spectrometry (PTR-MS) and simultaneous measurement of ammonia was used to achieve national emission estimates from field application of manure. Measurements were performed by placing a series of wind tunnels with realistic air flow rates in agricultural fields following application of liquid manure (slurry) and analyzing emissions over one week with a time resolution of typically 1 – 2 hours. The results demonstrate that emissions are significant and consist mainly of carboxylic acids with smaller contributions from phenols. Highly dynamic diurnal variations are identified. Impacts of different source types and manure treatments are discussed together with recommendations for future investigations.
Generating geospatial data products of ecosystem structure from LiDAR using Notebook-as-a-VRE (NaaVRE)
Authors: Shi Yifang , Koulouzis Spiros , Bianchi Riccardo , Timmermans Joris , Kissling W. Daniel , Zhao Zhiming
Published: February 2023

Quantifying ecosystem structure is of great importance for forest management, ecology, biodiversity monitoring, and climate change modeling. Advances in remote sensing — specifically Light Detection And Ranging (LiDAR) — have enabled the mapping of vegetation structure with unprecedented detail. However, considerable effort and advanced technical skills are required for researchers to process massive amounts of LiDAR data, giving the challenges in handling big data and high computational costs. Different requirements from end users also indicate that the FAIRness (i.e. Findability, Accessibility, Interoperability, and Reusability) of the processing workflow is needed for a broad user community. In this context, we developed a virtual research environment (VRE) solution for the Jupyter environment named Notebook-as-a-VRE, which allows users to search research assets (e.g. data, algorithms), compose workflows, manage the lifecycle of an experiment, and share the results among the user community. Functional components, including the component containerizer, the experiment manager, the VRE knowledge base, and the semantic search engine were deployed as Jupyter extensions on the user environment. In this way, users can encapsulate and containerize selected cells from Jupyter Notebook as standardized RESTful API services, use them for their customized workflows and publish the containerized cells or workflows as reusable components via community repositories. A high-throughput workflow called ‘Laserfarm’ was implemented in the NaaVRE for deriving geospatial data products of ecosystem structure at high resolution across the Netherlands. Geospatial data products containing 25 LiDAR-derived metrics were generated at 10 m resolution covering the whole Netherlands, representing open data on ecosystem height, ecosystem cover, and ecosystem structural complexity. The demonstrated NaaVRE solution can be flexibly expanded to other use cases in ecology, biodiversity, and the Earth science domain, with potential contributions to newly emerging national and regional biodiversity observation networks.
The IceWorm: an improved low-cost, low-power sensor for measuring dissolved CH4 in water bodies
Authors: Christiansen Jesper , Sapper Sarah Elise , Juncher Jørgensen Christian
Published: February 2023

Recent studies show emissions of dissolved methane (CH4) in the meltwater from the Greenland Ice Sheet. To better understand the phenomenon and evaluate its potential significance for the Arctic CH4 budget, continuous long-term measurements of dissolved CH4 concentrations are needed. Commercially available dissolved CH4 analyzers (DGEU-UGGA (LGR), CONTROS HydroC CH4 (Kongsberg) and Mini CH4 (pro-Oceanus)) generally have high power consumption and are very costly, limiting their operation in remote off-grid locations.Here we present calibrations and field tests of a low-cost, low-power alternative – the "IceWorm" - for long-term monitoring of dissolved CH4. The IceWorm uses a Figaro TGS2611-E00 metal oxide sensor (MOS). While MOS are cheap and power efficient, a known drawback is the sensitivity of the sensor's resistance to changes in humidity and temperature. In a previous prototype, we showed that by encasing the MOS in a hydrophobic and gas-permeable silicone membrane, a constant humidity in the headspace around the sensor can be achieved, yielding consistent results when deployed in glacial meltwater at constant temperature (0.0 – 0.1˚C)1. In this updated version, the sensor was encased in a hydrophobic and gas-permeable Teflon membrane allowing for fast (~1 min) equilibrium between the water and headspace around the sensor and hence a rapid detection of changes in dissolved CH4 concentrations.The first calibration was performed by exposing the IceWorm to stepwise increasing Two field calibrations of the sensor performance in meltwater at 0.0˚C were done: Afterwards, the sensors remained in the field for several weeks in the subglacial meltwater stream and the sensors were recalibrated in lab air under the same conditions to check for long-term sensor drift. Initially, field calibrated to measure dissolved CH4 in glacial meltwater at 0.0˚C, the IceWorm was also tested in a freshwater surface stream at temperatures between 1.6 – 15.7˚C. To account for the temperature difference, we compared the laboratory and field calibrations allowing us to correct the sensor output to temperature variations in the stream.We will present time series of long-term measurements of dissolved CH4 in two different types of water bodies and discuss the promising performance of the sensor at temperatures different to stable 0˚C as well as the usability of in-air calibrations compared to the field calibrations with discrete samples.1. Sapper et al. (2022) DOI:10.5194/egusphere-egu22-9972