bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating surface displacement in the Hanshin area, Japan, by PS-InSAR analysis using satellite Sentinel-1 data
Authors: Shigemitsu Yutaro , Ishitsuka Kazuya , Lin Weiren
Published: March 2021

The 2018 northern Osaka earthquake with a magnitude 6.1 earthquake struck on June 18, 2018 in northern Osaka, causing enormous damage. SAR interferometry using satellite synthetic aperture radar (SAR) data can detect surface displacement distribution over a wide area and is effective for observing surface displacement during an earthquake. On the other hand, it is also important to observe the tendency of long-term surface displacement around active faults on a yearly basis in order to monitor the deformation at and around active faults. In this study, we used persistent scatter SAR interferometry (PS-InSAR) to clarify the recent surface displacement including before and after the 2018 northern Osaka earthquake near the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment, near the epicenter of the earthquake. PS-InSAR analysis is a method that analyzes coherent pixels only, and can extract surface displacements with less noise than the conventional two-pass SAR interferometry. By using Sentinel-1 data, we expect to understand a long-term surface displacement and temporal changes in displacement pattern by comparing with the results using other satellites in previous studies. As a result of our analysis, we found that (i) ground subsidence occurred near the Mt. Rokko active segment, (ii) subsidence or eastward displacement occurred in the eastern part of the Takarazuka GNSS station, (iii) surface displacement in the wedge-shaped area located between the Arima-Takatsuki Fault Zone and the Mt. Rokko active segment is suggested to be caused by groundwater level changes, (iv) groundwater level changes may have caused surface displacement considered to be uplift in the wide area between the Ikoma Fault Zone and Uemachi Fault Zone, and (v) slip of the source fault may have caused surface displacement around the epicenter of the 2018 northern Osaka earthquake. Furthermore, we validated the estimated surface displacements by comparison with GNSS measurements and previous studies. These results suggest that surface displacement near the Arima-Takatsuki fault zone was caused by the 2018 northern Osaka earthquake. In order to reveal the mechanism of surface displacement in the vicinity of the fault, it is necessary to continue to monitor the surface displacement in this area using time-series SAR interferometry.

 

 

We acknowledge Sentinel-1 data provided from the European Space Agency (ESA) based on the open data policy.
Stress-testing groundwater and baseflow drought sensitivity to recharge
Authors: Hellwig Jost , Stoelzle Michael , Stahl Kerstin
Published: March 2021

Groundwater is the main source of freshwater and maintains streamflow during drought. Potential future groundwater and baseflow drought hazards depend on the systems' sensitivity to altered recharge conditions. We performed groundwater model experiments using three different generic stress tests to estimate the groundwater- and baseflow drought sensitivity to changes in recharge. The stress tests stem from a stakeholder co-design process that specifically followed the idea of altering known drought events from the past, i.e. asking whether altered recharge could have made a particular event worse. Here we show that groundwater responses to the stress tests are highly heterogeneous across Germany with groundwater heads in the North more sensitive to long-term recharge and in the Central German Uplands to short-term recharge variations. Baseflow droughts are generally more sensitive to intra-annual dynamics and baseflow responses to the stress tests are smaller compared to the groundwater heads. The groundwater drought recovery time is mainly driven by the hydrogeological conditions with slow (fast) recovery in the porous (fractured rock) aquifers. In general, a seasonal shift of recharge (i.e., less summer recharge and more winter recharge) will therefore have low effects on groundwater and baseflow drought severity. A lengthening of dry spells might cause much stronger responses, especially in regions with slow groundwater response to precipitation. Water management may need to consider the spatially different sensitivities of the groundwater system and the potential for more severe groundwater droughts in the large porous aquifers following prolonged meteorological droughts, particularly in the context of climate change projections indicating stronger seasonality and more severe drought events.
Idealized curved surface for mimicking slope failure: toward the sequential failure
Authors: Chi-Jyun Ko , Chih-Ling Wang , Hock-Kiet Wong , Yih-Chin Tai
Published: March 2021

In Tai et al. (2020), the concept of idealized curved surface (ICS) is proposed to mimic the failure surface, and the application to a large-scale landslide yields good agreement with the satellite image for the post-failure flow paths. The ICS consists of two constant curvatures in the down-slope and cross-slope directions, respectively. Hence, it is convenient to evaluate the stability based on the moment of momentum with respect to the plausible ICS. In this study we are going introduce a new formula for the stability analysis, in which the balance of angular momentum is employed, so that the local failure thickness (above the ICS) and the local ground water level can be taken into account. That is, the depth distribution of the landslide body may also have significant impacts on the slope stability.

Motivated by the similarity between landslide and granular avalanches, the periodic sand avalanches on a heap are investigated by means of the snap shots of high-speed camera, where the sand is accumulated up to a specific volume before sliding down. It is found that the first failure takes place near the toe of the avalanching body and the rupture surface develops and moves upwards. The ICS and the associated stability analysis can well explain the initial failure near the toe. This concept can also be applied to the mystery of the Hsiaolin landslide, taking place in southern Taiwan in 2009, where the released volume is up to more than 22 Mm3 but the mean slope is around 21 degrees. In spite of a 2D analysis, it can be found that, with a reasonable groundwater level, the first failure could be suspected to develop around the toe part. Therefore, we speculate that the plausible state of the landslide is the rainfall induced rise of groundwater level, inducing the sequential landslides and resulting the resultant large-scale landslide event.
Uncertainty in limb aerosol measurements following the Raikoke eruption
Authors: Rieger Landon , Bourassa Adam , Zawada Daniel , Degenstein Doug , Khaykin Sergey , Taha Ghassan
Published: March 2021

The eruption of Raikoke on June 22nd, 2019 was one of the largest in recent decades, spewing approximately 1.5 Tg of sulfur up to 17 km altitude. This eruption has been widely studied using a combination of climate models and measurement systems, including ground based lidars, in situ particle counters, and a variety of satellite platforms. The early plume has been well categorized by high-resolution measurements from CALIPSO, MODIS, VIIRS, IASI and other nadir viewing instruments, but as the plume ages investigation often shifts to limb sounding instruments that provide greater sensitivity to lower aerosol levels. These instruments have proven critical in understanding the long-term radiative and climatic impacts of stratospheric aerosol burdens after these explosive events, but the complexity of the measurements, sampling, and retrievals has made error characterization in high-loading conditions difficult.

This work explores systematic biases in limb measurements after the Raikoke eruption due to a variety of factors often implicit in the retrievals and analysis. Near-coincident CALIPSO, SAGE III and OMPS-LP measurements are used to investigate saturation of limb-sounding measurement in the early plume. The recent OMPS-LP v2 stratospheric aerosol product is compared with the University of Saskatchewan product to investigate benefits and drawbacks of the tomographic approach. SAGE III measurements are used as a validation when available although coverage limitations preclude comparisons in the thickest parts of the plume.  This work highlights the subtleties in comparing limb observations, with implications for model comparisons after large events such as volcanic eruptions and forest fires. Not only in the early plume, where sampling can be sparse, but also in the weeks and months following the eruption.
High-resolution and high-accuracy  global ionosphere maps estimated by GNSS and LEO constellations: simulative and real data experimental results
Authors: Ren Xiaodong , Chen Jun , Zhang Xiaohong
Published: March 2021

Global ionospheric total electron content (TEC) map has been employed in many high-precision areas. However, its spatial and temporal resolution is not ideal since the ground-based Global Navigation Satellite Systems (GNSS) stations distributed unevenly. Fortunately, many low earth orbit (LEO) satellite constellations will provide a large number of observations that can be used for ionospheric monitoring in the future. In this contribution, we presented two methods, which are the single-layer normalization (SLN) method and the dual-layer superposition (DLS) method, for ionospheric modeling based on the simulative and real data of GNSS+LEO satellites.

For simulative data, a constellation with 192 LEO satellites is simulated. And then,  the global ionospheric maps (GIMs) are estimated by all Multi-GNSS and simulative LEO satellite observations. The results showed that the root mean square (RMS) is reduced by approximately 25% and 21% for SLN method and DLS method, respectively. For real data,  20 available scientific LEO satellites, such as Jason-2/3, COSMIC-1/-2, Swarm missions, etc.,  are employed in the ground-based GNSS ionospheric modeling. The results showed that the differences between the ionospheric model estimated by GNSS+LEO and that by GNSS data are mainly over the oceanic region, which may exceed ±20 TECU. The improvement of RMS over the oceanic region is about 15% for the ionospheric model estimated by GNSS+LEO. The RMS of the ionospheric model improved approximately 4.0% compared with that by GNSS data using the dSTEC assessment method.
Absorbed dose rate assessment for the Japanese cedar stand affected after the Fukushima NPP accident.
Authors: Mikailova Rena , Onda Yuichi , Fesenko Sergey , Kato Hiroaki
Published: March 2021

The nuclear disaster from the FNPP accident resulted in the major contamination of forest ecosystem of Eastern Japan. Forests are the most susceptible to ionizing radiation exposure, especially conifers due to their high radiosensitivity and pollutant interception abilities. A high concentration of radionuclides in forest ecosystems caused an increase in the dose rate. Japanese cedar belongs to Japan's endemic species; therefore, the current study was aimed at the absorbed dose rate assessment of the C. japonica forest stand in the Yamakiya district. To estimate the absorbed dose rates to the Japanese cedar trees, we used the 134,137Cs concentrations in different forest ecosystems’ compartments. The calculations include data from 2011 to 2017. The dose rate assessments were performed at different heights of the forest ecosystem (canopy, trunk, understory). The average dose rates decreased from 40 µGy/day in 2011 to 13 µGy/day in 2017. The assessment results comply with the ambient dose rate measured from 2011 to 2015. The assessment showed that the water content in the litter and topsoil layers significantly influence the formation of the dose rate. Via the model, we simulated the dose rates for 20% and 80% of the litter water content. The results showed that the average measured dose rates lie within the estimated results. Due to the lack of data on litter and soil moisture during sampling, now we are trying to calculate the ground layers’ water content using the available information on precipitation rate.
How are Global Extreme Temperature and Precipitation Events Changing?
Authors: Huning Laurie
Published: March 2021

As the global temperature increases, the likelihood of extreme temperature and precipitation events occurring is expected to change across many parts of the world. In particular, a warmer world can alter the spatiotemporal characteristics (e.g., intensity, magnitude, distribution, frequency) and patterns of such events. The changing character of extreme events in the future can have substantial impacts (e.g., flooding, drought) that affect our society, built and natural environments, and food, water, and energy systems. We therefore must better understand and quantify how the distribution of temperature and precipitation are changing. In this study, the Coupled Model Intercomparison Project phase 6 (CMIP6) simulations are used to characterize shifts in the distribution of temperature and precipitation as they vary across space and time using both historical simulations and projections. This research demonstrates how different parts of these distributions exhibit nonlinear changes (e.g., the hottest and wettest events) in the future. This study also characterizes inter-model differences to better assess uncertainty across historical simulations and projections as well as how human activities influence extreme events.
Decoding geochemical signals of the Schwalbenberg Loess-Palaeosol-Sequences — A key to Upper Pleistocene terrestrial ecosystem responses in western Central Europe 
Authors: Vinnepand Mathias , Fischer Peter , Zeeden Christian , Schulte Philipp , Fiedler Sabine , Jöris Olaf , Hambach Ulrich , Fitzsimmons Kathryn , Prud'homme Charlotte , Péric Zoran , Schirmer Wolfgang , Lehmkuhl Frank , Vött Andreas
Published: March 2021

The Schwalbenberg Loess-Palaeosol-Sequences (LPS) in the Middle Rhine Valley, Germany, comprise unprecedented complete records of Upper Pleistocene terrestrial ecosystem response to global climate changes. However, direct correlation of the Schwalbenberg geochemical signals with climate archives of supra-regional northern hemispheric relevance remains complicated. This is due to the complex interplay of pre-, syn-, or post-depositional processes that left their traces in the terrestrial record. In particular, the use of different element ratios to derive weathering indices may be complicated as dust sources change through time, and as ecosystems respond to changing conditions. In this study, we decode interfering geochemical signatures and re-evaluate proxies, commonly applied, regarding their suitability and meaning for understanding the evolution of the Schwalbenberg LPS. We undertake a systematic approach, firstly dividing the 30 m long Schwalbenberg REM3 LPS according to our core description. In a second step, we integrate LOG-ratios indicative of provenance shifts, sediment reworking dynamics and weathering into multivariate analysis. We apply Principle Component Analyses (PCA) and Linear Discriminant Analysis (LDA) to datasets comprising sediments deposited under similar environmental conditions. In doing so, we sensitively quantify subordinate processes and conditions, such as the impact of varying source- and weathering-signals in all proxies. Our results show that in particularly K/Rb and Mg/Ca ratios contain a strong provenance signal in loess deposits, whereas the Ca/Ald ratio (Ald: dithionite extractable) best indicates the maturity state of Gelic Gleysols. Integration of our filtered datasets with a high-resolution age model enables direct correlation of the variability of principal components on sub-millennial scales with Atlantic-driven climate oscillations. More specifically, PC2 appears to reflect changes in mineral dust accumulation and indicates increasing dust input in response to climate cooling towards the end of interstadials, highlighting the accretionary nature of the Schwalbenberg LPS during transitional periods from interstadial to stadial depositional modes.

 
Increase of ice discharge from Greenland's peripheral tidewater glaciers over recent decades
Authors: Möller Marco , Recinos Beatriz , Marzeion Ben
Published: March 2021

The Greenland Ice Sheet is losing mass at increasing rates. Substantial amounts of this mass loss occur by ice discharge. The ice sheet is surrounded by thousands of peripheral glaciers, which are dynamically decoupled from the ice sheet, and which account for ~10 % of the global glacier ice volume outside the two main ice sheets. Rather low-lying along the coasts, these peripheral glaciers are also losing mass at increasing, but disputed, rates. The total absence of knowledge about the role and share of solid ice discharge in this mass loss adds to the controversy. Since the quantification of ice discharge is still pending, a full understanding of ice mass loss processes in this globally important glacier region is substantially hampered.

Here, we present the first estimation of ice discharge from Greenland's peripheral tidewater glaciers. For each of these 760 glaciers, we combine an idealized rectangular flux gate cross sections derived from modelling with the Open Global Glacier Model with surface ice flow velocities derived from the ITS_LIVE and MEaSUREs remote sensing datasets to calculate glacier specific ice discharge on both annual and multi-annual time scales over the period 1985 to 2018. For the few glaciers not covered by either of the employed original datasets or modelling methods we use a regression tree-based extrapolation scheme to estimate the necessary input data for our calculation.

Our findings indicate a significant overall increase of ice discharge over the study period although several individual glaciers show contrasting developments. This increase became especially apparent across the southern parts of Greenland. Our results also show that the total of the ice discharge from Greenland's peripheral tidewater glaciers is dominated by few major contributors and that this dominance is completely time-independent.
Multilayer Perceptron Neural Networks for Estimating Missing Rainfall Data
Authors: Narimani Roya , Changhyun Jun
Published: March 2021

The quality and completeness of rainfall data have always played an important role in time series analysis and prediction for future water-related disasters. It requires to estimate missing data correctly for better results of rainfall prediction with high accuracy. In recent years, multilayer perceptron (MLP) neural networks have been applied to solve stochastic problems in data science. This study suggests a novel approach for estimating missing rainfall data with MLP neural networks. For this purpose, a mathematical model was created to analyze and predict the time series of daily rainfall data from 2003 to 2017 at six rain gauge stations in Seoul, Korea. Here, rainfall data with missing values during 20 days of time periods was considered for reconstruction of missing data at one specific rain gauge station from complete rainfall data records at five different stations. They were divided into training, validation, and testing datasets with a percentage of 70%, 15%, and 15%, respectively. This study investigates an effect of changes in data periods considered in MLP neural networks and it indicates that rainfall time series for a longer time period play a more effective role in rainfall data reconstruction.
The impact of severe storms on forecasting the Ionosphere-Thermosphere system through the assimilation of SWARM-derived neutral mass density into physics-based models
Authors: Fernandez-Gomez Isabel , Goss Andreas , Schmidt Michael , Kosary Mona , Kodikara Timothy , Forootan Ehsan , Borries Claudia
Published: March 2021

The response of the Ionosphere - Thermosphere (IT) system to severe storm conditions is of great importance to fully understand its coupling mechanisms. The challenge to represent the governing processes of the upper atmosphere depends, to a large extent, on an accurate representation of the true state of the IT system, that we obtain by assimilating relevant measurements into physics-based models. Thermospheric Mass Density (TMD) is the summation of total neutral mass within the atmosphere that is derived from accelerometer measurements of satellite missions such as CHAMP, GOCE, GRACE(-FO) and Swarm. TMD estimates can be assimilated into physics-based models to modify the state of the processes within the IT system. Previous studies have shown that this modification can potentially improve the simulations and predictions of the ionospheric electron density. These differences could also be interpreted as an indicator of the ionosphere-thermosphere interaction. The research presented here, aims to quantify the impact of data satellite based TMD assimilation on numerical model results.

Subject of this study is the Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe) physics-based model in combination with the recently developed Thermosphere-Ionosphere Data Assimilation (TIDA) scheme. TMD estimates from the ESA’s Swarm mission are assimilated in CTIPe-TIDA during the 16 to the 20 of March 2015. This period was characterized by a strong geomagnetic storm that triggered significant changes in the IT system, the so-called St. Patrick day storm 2015. To assess the changes in the IT system during storm conditions due to data assimilation, the model results from assimilating SWARM mass density normalized to the altitude of 400 km are compared to independent thermospheric estimates like GRACE-TMDS. In order to evaluate the impact of the data assimilation on the ionosphere, the corresponding output of electron density is compared to high-quality electron density estimates derived from data-driven model of the DGFI-TUM.
Investigating the Response of Tectonic Loading in the Himalayas on the Peripheral Forebulge through Drainage Network Analysis
Authors: Kasana Parv , Singh Vimal , Devrani Rahul
Published: March 2021

Drainage divide migration is a conspicuous natural process through which a landscape evolves. In response to a forced climatic and tectonic disturbance, susceptible river networks transfer the transient signals to the entire river basin, which results in an incision or aggradation. The Himalayan orogeny and subduction of the Indian plate have resulted in an upward flexure in the Indian lithosphere known as a peripheral forebulge. A forebulge can flexurally uplift and migrate following the variation in tectonic load. The emergence of the central Indian plateau is a consequence of the upwarping of the Indian lithosphere (Bilham et al. 2003).  In this work, we are trying to assess the drainage network dynamics between the Narmada and Ganga river systems, which drain the uplifted central Indian plateau. We have calculated the Chi(χ) metrics, steepness index (Ksn), knickpoints for the channels in the study area. We have generated Topographic swath profiles to analyze the topographic variations on the plateau. It has been observed from the results that the rivers in the study area lack dynamic equilibrium, and river capturing is an evident response to the perturbations. Our analysis shows that the Narmada River tributaries are gaining drainage area and aggressing Northwards by capturing adjacent Ganga river tributaries. The field observations show a variation in the surface slope and presence of knickpoints (waterfalls) along the "aggressor" drainages. We propose a model to show a correlation between the tectonic loading of Himalayas, movement of forebulge, and its feedback to the river systems present on the forebulge.
Whodunnit? Solving the mysteries of soil phosphorus solubilisation in an ectomycorrhizal tripartite interaction
Authors: Stuart Emiko , McDonald Catriona , Castañeda-Gómez Laura , Wong-Bajracharya Johanna , Anderson Ian , Carrillo Yolima , Plett Jonathan , Plett Krista
Published: March 2021

Temperate and boreal forest trees are dependent on soil microorganisms for the acquisition of limiting nutrients, including phosphorus. These include ectomycorrhizal fungi, which form a symbiotic association with the roots of the trees, and soil-dwelling bacteria. The exact roles of and mechanisms used by ectomycorrhizal fungi and soil bacteria in plant phosphorus nutrition and phosphorus cycling are unclear, as are the effects of fungal identity and nutrient availability on these processes.

We compared the effects of inoculation with two species from the ectomycorrhizal fungal genus Pisolithus on the amounts of phosphorus available to and present in Eucalyptus grandis seedlings, under different levels of nitrogen fertilisation and atmospheric CO2. We then further explored the phosphorus-solubilising abilities of the fungi and soil bacterial community using in vitro plate assays, soil enzymatic assays and qPCR analyses.

We show evidence of synergistic interactions between the ectomycorrhizal fungi and soil bacterial community to improve phosphorus nutrition in the soil – interactions that are impacted by both nitrogen and CO2 levels and the species of the fungus. Our findings expand the current understanding of how ectomycorrhizal fungi and soil bacteria contribute to forest tree phosphorus nutrition and reveal how this interaction has important implications for sustainable forest management practices and estimations of future climate impacts on forest ecosystems.
Radial diffusion coefficients database in the frame of SafeSpace project
Authors: Katsavrias Christos , Daglis Ioannis A. , Nasi Afroditi , Papadimitriou Constantinos , Georgiou Marina
Published: March 2021

Radial diffusion has been established as one of the most important mechanisms contributing the acceleration and loss of relativistic electrons in the outer radiation belt. Over the past few years efforts have been devoted to provide empirical relationships of radial diffusion coefficients (DLL) for radiation belt simulations yet several studies have suggested that the difference between the various models can be orders of magnitude different at high levels of geomagnetic activity as the observed DLL have been shown to be highly event-specific. In the frame of SafeSpace project we have used 12 years (2009 – 2020) of multi-point magnetic and electric field measurements from THEMIS A, D and E satellites to create a database of calculated DLL. In this work we present the first statistics on the evolution of DLL during the various phases of Solar cycle 24 with respect to the various solar wind parameters and geomagnetic indices.

This work has received funding from the European Union's Horizon 2020 research and innovation programme “SafeSpace” under grant agreement No 870437.
An evaluation of the effectiveness of known large-scale modes for predicting extreme Mei-yu precipitation over China using causality driven approach
Authors: Ng Kelvin , Leckebusch Gregor , Hodges Kevin
Published: March 2021

Record-breaking amount of Mei-yu rainfall around the Yangtze River has been observed in the 2020 Mei-yu season.  This shows the necessity and urgency of accurate prediction of extreme Mei-yu precipitation over China for the current and future climate.  Such information could further improve the decision and policy making in the region.  Many studies in the past have shown that large-scale modes, e.g. western north Pacific subtropical high and the south Asia high, play a role in controlling extreme Mei-yu precipitation over China. Although the spatial resolution of typical climate models might be too coarse to simulate extreme precipitation accurately, they are likely to simulate large-scale modes reasonably well.  One might be possible to construct a causally guided statistical model based on those known large-scale modes to predict extreme Mei-yu precipitation. 

In this presentation, we show preliminary results of the relationship between known large-scale atmospheric and oceanic modes and extreme Mei-yu precipitation in the two regions of China, i.e. Yangtze River Valley and Southern China, using the causal network discovery approach.  The relationships between large-scale modes and extreme Mei-yu precipitation on different time scale are explored.  Implication of relationships in constructing statistical predictive model is also discussed.
Slab tearing of the Nazca plate in the Central Andes and its interaction with the overriding plate
Authors: Nakrong Nipaporn (Nidnueng) , Spakman Wim , Chen Fangqin , Lister Gordon
Published: March 2021

Slab tearing in subducting plates is widely implicated in terms of the factors that control the evolution of the structural geology of the over-riding crust, here illustrated by interactions between the subducting Nazca plate and the overlying overthrust western continental margin of South America. We examine the different ways that structures above the bounding megathrusts are linked to the ripping and tearing of the subducting plate beneath, in particular focussed on the Andean orogeny at the Arica bend during the formation of the Bolivian orocline. We can create models for slab tearing by integrating seismotectonic analysis, seismic tomography, and morphotectonics. There are many features in the UU-P07 tomographic model that we cannot yet relate to the evolution of surface structure, for example, the gaps and tears beneath the Bolivian Orocline, or the separation of the detached slab we interpret as a paleo-segment of the Nazca plate, illustrating traces of an ancient subduction system. However, we can link the evolution of some surface structures to the growth of the giant kink of the Nazca slab that connects to the surface near the Arica bend. This may have driven strike-slip faulting with opposing sense-of-shear, northern south of the Bolivian Orocline. Megathrust rupture segments may be related to the polygonal kinked trace of the orogen, which is not at all a continuously curved arc. In this contribution, we relate the growth and accentuation of the Arica Bend to the evolution of the giant kink in the Nazca plate using a 4-D tectonic reconstruction.
Sustainable Development Goal Conflicts in Re-Mining of Tailings
Authors: Büttner Philipp , Gutzmer Jens , Engelhardt Jonathan , Martin Mirko
Published: March 2021

The Davidschacht tailings storage facility (TSF), operated from 1944 to 1964, represents one of the largest tailings dams in the historic Freiberg mining district. It contains a volume of 760,000 m³ of sulfidic flotation tailings, residues of former base metal and silver ore beneficiation. The tailings material still contains elevated concentrations of valuable elements such as zinc (0.4 wt.% on average), lead (0.2 wt.%) and copper (0.05 wt.%) as well as indium (10 ppm). The material has thus become the focus of efforts to enable eventual re-mining and recovery of valuable metals. However, such efforts have to take into account a number of important interests of the public. The first of these is the fact that the unrehabilitated tailings pose a significant risk to the environment. Cd (44 ppm on average) and As (0.6 wt.%) concentrations are particularly high – and have a marked influence on the adjacent water bodies, such as the Freiberg Mulde river. Curbing this influence has been the subject of multiple remediation studies, but pressure to act has risen recently due to increasing regulatory demands on the quality of surface water (EU Water Framework Directive of 2000). This is, in principle, very much in favor of re-mining the tailings in an effort to remove also hazardous components. Counteracting this reclamation scenario is the fact that the TSF is part of the UNESCO World Heritage Site “Erzgebirge / Krusne Hory” that was awarded in 2019. Another restriction pertains to the highly protected status of individual species (esp. sand lizard) settling on the TSF surface. This constellation obviously provides ample space for discussion as to how to deal with the tailings material contained in the Davidschacht TSF in future. Different sustainable development goals (SDG) have to be weighed against each other in order to find a holistic and sustainable. Airlift reactor-based bioleaching has been considered as an opportunity to maximize the sustainability of re-mining activities on the Davidschacht TSF. This innovative approach – and its circumstantial limitations – are documented in this contribution.
Inverse modeling of transient three-dimensional core-scale two-phase flows
Authors: Manzoni Andrea , Dell'Oca Aronne , Siena Martina , Guadagnini Alberto
Published: March 2021

We consider transient three-dimensional (3D) two-phase (oil and water) flows, taking place at the core-scale. In this context, we aim at exploiting the full information content associated with available information of (i) the 3D distribution of oil saturation and (ii) the overall pressure difference across the rock sample, to estimate the set of model parameters. We consider a continuum-scale description of the system behavior upon relying on the widely employed Brooks-Corey model for the characterization of relative permeabilities and on the capillary pressure correlation introduced by Skjaeveland et al. (2000). To provide a transparent way of assessing the results of the inversion, we rely on a synthetic reference scenario. The latter is intended to mimic having at our disposal 3D and section-averaged distributions of (time-dependent) oil saturations of the kind that can be acquired during typical laboratory experiments. These are in turn corrupted by way of a random noise, to address the influence of experimental uncertainties. We focus on diverse scenarios encompassing imbibition and drainage conditions. We employ two population-based optimization algorithms, i.e., (i) the particle swarm optimization (PSO); and (ii) the differential evolution (DE), which enable one to effectively tackle the high-dimensionality parameters space (i.e., 12 dimensions in our setting) we consider. Model calibration results are of satisfactory quality for the majority of the tested scenarios, whereas the DE algorithm is associated with highest effectiveness.

References

S.M. Skjaeveland; L.M. Siqveland; A. Kjosavik; W.L. Hammervold Thomas; G.A. Virnovsky (2000). Capillary Pressure Correlation for Mixed-Wet Reservoirs SPE Res Eval & Eng 3 (01): 60–67. https://doi.org/10.2118/60900-PA
Estimation of the tidal energy potential in the Scheldt estuary using a three-dimensional unstructured hydrodynamic model
Authors: Levasseur Anne , Gousset Hadrien , Le Bris Delphine
Published: March 2021

The objective of this work is to assess the tidal stream energy potential in the Scheldt estuary, through the application of technical specifications from the International Electrotechnical Commission (IEC). The IEC TS 62600-201:2015 establishes a system for analysing and reporting, through estimation or direct measurement, the theoretical tidal current energy resource in oceanic areas including estuaries.

Velocity distribution at the potential deployment site is examined using a high-resolution three-dimensional model of the ocean currents based on the TELEMAC system. The mesh size ranges from 400 m at the mouth of the estuary to 50 m near the potential pilot sites. The unstructured mesh size allows a realistic representation of the detailed bathymetric features, the narrow straits and channels where the most intense currents are. The model is forced at the lateral boundaries with sea surface elevation predicted by the global tidal model Finite Element Solution 2012 (FES 2012) and the river flow from the Scheldt River. The model is calibrated using public data obtained from water level measurements at the ports of Vlissingen, Breskens and Cadzand.

The velocity magnitude and direction calculated over one month at the pilot site are extrapolated over a year by means of a harmonic analysis. At the depth of the tidal current turbine (-2.5m below the sea level), the annual mean of the velocity magnitude is 0.7 m/s with a maximum of 1.6 m/s for the selected pilot site. Velocity magnitudes are in the range of 0.5 to 1 m/s for 54.9% of the time, and above 1 m/s for 17.7% of the time. There are two prevailing directions for the water flow: 47% of current velocity is eastward (direction 70°-90°N) and 46% is westward (direction 250°-260°N). The expected annual energy production is calculated using the modelled velocity distribution and the technical characteristics of the vertical axis water turbine developed by Water2Energy.

The results of this analysis shows that the site has limited potential in terms of energy production.  However, the site could still be relevant as a pilot demonstration site for shorter durations. The analysis based on IEC technical specifications will be useful for the identification and comparison of more energetic sites in the future. Also, this results provides feedback to the IEC on the usability of the technical specification for improvements.

This work is part of the ENCORE project (ENergizing COastal Regions with Offshore Renewable Energy), which aims is to advance four offshore renewable energy technologies through the application of IEC technical specifications in a structured and collaborative process. ENCORE is funded by the European Interreg 2 Seas programme and co-funded by the European Regional Development Fund (ERDF) under grant agreement No 2S08-004.
Solar Orbiter observations of solar wind current sheets and their deHoffman-Teller frames
Authors: Steinvall Konrad , Khotyaintsev Yuri , Cozzani Giulia , Vaivads Andris , Owen Christopher , Fedorov Andrey , Louarn Philippe ,   RPW Team, SWA Team, MAG Team
Published: March 2021

Solar wind current sheets have been extensively studied at 1 AU. The recent advent of Parker Solar Probe and Solar Orbiter (SolO) has enabled us to study these structures at a range of heliocentric distances.

We present SolO observations of current sheets in the solar wind at heliocentric distances between 0.55 and 0.85 AU, some of which show signatures of ongoing magnetic reconnection. We develop a method to find the deHoffman-Teller frame which minimizes the Y-component (the component tangential to the spacecraft orbit) of the electric field. Using the electric field measurements from RPW and magnetic field measurements from MAG, we use our method to determine the deHoffman-Teller frame of solar wind current sheets. The same method can also be used on the Alfvénic turbulence and structures found in the solar wind to obtain a measure of the solar wind velocity.

Our preliminary results show a good agreement between our modified deHoffmann-Teller analysis based on the single component E-field, and the conventional deHoffman-Teller analysis based on 3D plasma velocity measurements from PAS. This opens up the possibility to use the RPW and MAG data to obtain an estimate of the solar wind velocity when particle data is unavailable.
A Global Survey of Geospace Electrons with eVlasiator: First Results
Authors: Alho Markku , Battarbee Markus , Pfau-Kempf Yann , Ganse Urs , Turc Lucile , Johlander Andreas , Tarvus Vertti , Zhou Hongyang , Dubart Maxime , Grandin Maxime , Papadakis Konstantinos , Suni Jonas , George Harriet , Bussov Maarja , Palmroth Minna
Published: March 2021

Models of the geospace plasma environment have been proceeding towards more realistic descriptions of the solar wind—magnetosphere interaction, from gas-dynamic to MHD and hybrid ion-kinetic models such as the state-of-the-art Vlasiator model. Advances in computational capabilities have enabled global simulations of detailed physics, but the electron scale has so far been out of reach in a truly global setting. 

In this work we present results from eVlasiator, an offshoot of the Vlasiator model, showing first results from a global 2D+3V kinetic electron geospace simulation. Despite truncation of some electron physics and use of ion-scale spatial resolution, we show that realistic electron distribution functions are obtainable within the magnetosphere and describe these in relation to MMS observations. Electron precipitation to the upper atmosphere from these velocity distributions is estimated.
The added value of downscaling for high mountain sites
Authors: Hofer Marlis , Horak Johannes
Published: March 2021

The availability of in situ atmospheric observations decreases with elevation and topographic complexity. Data sets based on numerical atmospheric modeling, such as reanalysis data sets, represent an alternative source of information, but often suffer from inaccuracies, e.g., due to insufficient spatial resolution. In this contribution, we investigate the added value of sDoG, a reanalysis data postprocessing and downscaling tool designed to extend short-term and/or interrupted weather station data from high mountain sites to the baseline climate. sDoG is applied to ERA interim predictors to produce a retrospective forecast of daily air temperature at the Vernagtbach climate monitoring site (2640 MSL) in the Central European Alps. sDoG training and cross-validation is based on observations from 2002 to 2012. The availability of observations at the Vernagtbach climate monitoring site further back in time allows us to perform a true evaluation: "true evaluation" in contrast to cross-validation, by assessing the performance of the sDoG retrospective forecast for the period 1979 to 2001.

We demonstrate the ability of sDoG in modeling air temperature in the true evaluation period for different temporal scales. sDoG adds significant value over a selection of reference data sets, including state-of-the-art global and regional reanalysis data sets, output by a regional climate model, and an observation-based gridded product (SPARTACUS). However, we identify limitations of sDoG in modeling summer air temperature variations, most probably related to changes of the microclimate around the Vernagtbach climate monitoring site that violate the stationarity assumption underlying sDoG. Comparing the performance of the considered reference data sets reveals that higher resolution data sets do not necessarily add value over data sets with lower spatial resolution. For example, the global reanalyses ERA5 (31 km resolution) and ERA interim (80 km resolution) both clearly outperform the higher resolution surface analyses ERA5-Land (11 km resolution), HARMONIE (11 km resolution), and UERRA MESCAN-SURFEX (5.5 km resolution). Performance differences amongst ERA5 and ERA interim, by contrast, are comparably small. The results highlight the importance of station-scale uncertainty assessments of atmospheric numerical model output and downscaling products for high mountain areas, both for data users and model developers.
 Middle and Late Jurassic climatic, oceanographic and environmental trends along the Viking Corridor
Authors: Hougård Iben W. , Vickers Madeleine L. , Alsen Peter , Jelby Mads E. , Ullmann Clemens V. , Korte Christoph
Published: March 2021

Keywords: Late Jurassic; palaeoclimate; Greenland; carbon cycling; Viking Corridor; belemnite stable isotopes

The “polar amplification” effect, whereby the poles experience greater changes in temperature compared to the low latitudes for a given global average temperature change, makes high-latitude isotope records ideally suited to investigate fluctuations in palaeoclimate. The present study investigates palaeoclimatic and oceanographic changes along the Viking Corridor – the narrow seaway that connected the Tethys to the Arctic Boreal Realm during the Middle and Late Jurassic.

Stable-isotope data obtained from belemnites from East Greenland, originating from along the western margin of the Viking Corridor, show a M. Bathonian warming trend, which may indicate the reopening of the corridor after North Sea doming. We also discuss various controls on the carbon-isotope record that may dampen or amplify global signals. Changes in local depositional settings caused partial overprinting of the δ13C record during the Late Jurassic VOICE event.
(Re)politicizing disaster governance: Simulating Conflicting Interests Over Matters of Concern By Means Of A Board Game
Authors: Mertens Kewan , Delima Gina
Published: March 2021

The disaster risk reduction (DRR) community tends to treat disasters and risk in a managerial and technocratic way, thereby disregarding the highly political nature of DRR. An alternative epistemology of disasters, as matters of concern, is proposed and tested. Mobilizing concepts from Chantal Mouffe and Bruno Latour, this paper illustrates how DRR can be transformed into a public issue. It is argued that education and policy making on DRR would benefit from a recognition of the hybrid nature of disasters. A serious game is used to test proposed epistemology. The board game simulates political decision making on the reduction of risks due to floods and landslides in West Uganda. It is hypothesized that the game can generate an ideal speech scenario that fosters discussions among players and possibly even creates a space of political confrontation. Discussions during ten gameplays in South-West Uganda have been recorded and transcribed. Participants effectively experience affects, power relations and confrontations during the game, but a call for consensus and technical solutions are sometimes used to prematurely close the discussions and move on with concrete solutions. Insights from this paper contribute to understanding why DRR is frequently treated as a technical issue in local and international disaster governance. Proposed epistemology and approaches are expected to stimulate innovative experiments towards a more political approach of DRR education and policy.
A review of worldwide sediment core dating research including fallout radiocaesium (137Cs)  
Authors: Foucher Anthony , Sabatier Pierre , Chaboche Pierre-Alexis , Evrard Olivier
Published: March 2021

Dating recent sediment archives (<150 years) constitutes are need for environmental and climatic reconstructions. Radiocaesium (137Cs) emitted during thermonuclear bombs testing (~1950 - ~1980) and nuclear accidents (1986 and 2011) was generally used for identifying sediment sources or for establishing sediment core chronology based on discrete time markers. Although this method was widely used during the last several decades, there is a lack of structured and comprehensive worldwide synthesis of radiocaesium fallouts. The current literature overview was based on 573 articles published between 1977 and 2020, reporting the collection of 1351 individual dated sediment cores. This synthesis led to the identification of the worldwide distribution of discrete time markers associated with the thermonuclear bomb testing peak in 1963, the Chernobyl fallout, the Fukushima fallout, as well as the identification of at least 25 events induced by local accidents or nuclear tests (e.g. Sellafield, la Hague accidents, Chinese nuclear tests).

With a growing number of studies focusing on the analysis of recent sediment cores and the increasing interest in sediment fingerprinting techniques, this spatialized synthesis provides a unique worldwide referential for identifying the distribution of the 137Cs sources at global scale. It also outlines the main questions that would deserve attention in future research perspectives and the regions where 137Cs fallouts investigations should be conducted in priority.