bluuebunny/crossref_metadata_2025 huggingface dataset:
Cloud Microphysical Characteristics Associated with Blue Corona Discharges at thundercloud tops
Authors: Li Dongshuai , Luque Alejandro , Neubert Torsten , Chanrion Olivier , Zhu Yanan , Lapierre Jeff , Østgaard Nikolai , Reglero Víctor
Published: March 2024

Blue corona discharges are bursts of streamer discharges often observed at the top of thunderclouds, but the conditions in the clouds that generate them are not well understood.The cloud microphysical parameters related to them are important for future empirical studies and for theoretical models and simulations. Previous studies modeled the scattering and absorption emissions from blue corona discharges by assuming mean particle radius of 10–20 μm and densities of 1–2.5 × 10^8 m^−3, resulting in photon mean free paths of 1–20 m.Here we present the first-ever estimate of important microphysical parameters related to blue corona discharges based on data measurements from the CALIPSO lidar. The results showed that most blue corona discharges were associated with ice particles with a radius of ∼50 μm and a number density of ∼ 2 × 10^7 m^−3, resulting in a photon mean free path of ∼3 m.Around 20% of the blue corona discharges coincide with Narrow Bipolar Events (NBEs) indentified from the Earth Networks Total Lightning Network.The altitudes of blue corona discharges that were identified as NBEs are derived from both the optical and radio bands. It revealed that in six out of nine cases, the R^2 value was greater than 0.85, indicating a good agreement between the two methods and supporting our estimate of the photon mean free path as 3 m. However, in the shallowest and deepest cases, there was some discrepancy between the altitudes determined by the two methods, suggesting more complex cloud microphysical parameters. Possible reasons for the discrepancy, such as the homogeneous approximation for the cloud's microphysical parameters and the simplification of the source length, will be discussed.
Mars Singular Clouds: Dots, Rings and Narrow-Elongated
Authors: Sanchez-Lavega Agustin , Hernandez-Bernal Jorge , Larsen Ethan , del Rio-Gaztelurrutia Teresa , Sánchez-Cano Beatriz , Määttäanen Anni
Published: March 2024

We report two extreme cases of clouds in Mars, on the one hand what we call “isolated dot clouds” and on the other hand new cases of extremely “elongated long and narrow clouds” reminiscent in their shape of the one that develops in Arsia Mons. We use the images obtained by the VMC-camera on board the Mars Express mission that from its advantageous polar elliptical orbit allows to image Mars at different local times (in particular at twilight hours).We present the properties of the “dot clouds” that develop abundantly in the Terra Cimmeria region, particularly around the Kepler crater (longitude 140.9 East and 46.8 South) in Mars solar longitudes Ls from 30 to 100 deg. These are compact rounded clouds with sizes of about 50 km in diameter and altitudes in the range 50-80 km as measured from their shadows. Sometimes they appear isolated at dawn, others in twilight clusters, but we also present a singular case in which they exhibited a ringed shape. We discuss possible mechanisms underlying their formation, such as convection and the possible intervention of the crustal magnetic field concentrated in this region.  On the other hand, we report new cases of extremely narrow and elongated clouds observed at mid and high latitudes in both hemispheres. We study in particular the properties of these clouds in the volcanic region of Alba Patera, in Thaumasia Highlands and in Lyot crater, where they can reached lengths from 1,000 km to 2,000 km and widths of 50 km.  
Mercury's Helium Exosphere determined by Ion Cyclotron Waves
Authors: Weichbold Fabian , Lammer Helmut , Schmid Daniel , Volwerk Martin , Hener Jonas , Vorburger Audrey , Wurz Peter
Published: March 2024

Mariner 10 detected the existence of an exosphere around Mercury in 1974-1975 by remote spectrometric observations during flybys. More than four decades later the MErcury Surface, Space ENvironment, Geochemistry and Ranging (MESSENGER) spacecraft confirmed the existence of the exosphere. So far, the neutral helium (He) number density around Mercury’s exosphere was based on assumptions related to the spectroscopic observations, which are applied to exospheric models to derive an altitude-dependent density profile of the neutral helium around the planet. Here, we present the first on-site measured density profile of He, using in-situ magnetic field measurements from MESSENGER. These data were analyzed for the identification of Ion-Cyclotron Waves (ICWs) that originated from exospheric pick-up He+ ions. The results reveal an extended He-exosphere with a lower surface number density as expected by previous studies. To provide further context, the results are compared with measurements obtained by Mariner 10 and BepiColombo (first flyby), which shows that the measurements of the PHEBUS UV-instrument onboard of the MPO align very well with the determined density from this study.
A Time-Series Analysis of Rockfall Evolution in a Coastal Region Using Remote Sensing Data
Authors: Konsolaki Aliki , Vassilakis Emmanuel , Kotsi Evelina , Diakakis Michalis , Mavroulis Spyridon , Petrakis Stelios , Filis Christos , Lekkas Efthymios
Published: March 2024

The evolution of technology, particularly the integration of Unmanned Aerial Systems (UAS), earth observation datasets, and historical data such as aerial photographs, stand as fundamental tools for comprehending and reconstructing surface evolution and potential environmental changes. In addition, the active geodynamic phenomena in conjunction with climate crisis and the increasing frequency of extreme weather phenomena can cause abrupt events such as rockfalls and landslides, altering completely the morphology on both small and large scales.This study deals generally with the temporal evolution of landscapes and specifically focuses on the detection and quantification of a significant rockfall event that occurred at Kalamaki Beach on Zakynthos Island, Greece – a very popular summer destination. Utilizing UAS surveys conducted in July 2020 and July 2023, this research revealed a rockfall that has significantly altered the coastal morphology. During this period, two severe natural phenomena occurred, one of which could potentially be the cause of this rockfall event. Initially, the Mediterranean hurricane (‘medicane’) ‘Ianos’ made landfall in September 2020, affecting a large part of the country including the Ionian Islands. The result was severe damage to property and infrastructures, along with human casualties, induced by intense precipitation, flash flooding, strong winds, and wave action. Second, in September of 2022, an ML=5.4 earthquake struck between Cephalonia and Zakynthos Islands in the Ionian Sea, triggering considerable impact in both islands. The study employs satellite images postdating these natural disasters, to detect the source of the rockfall in Kalamaki Beach. Additionally, historical analog aerial images from 1996 and 2010 were used as assets for understanding the surface’s evolution. For the quantitative analysis, we applied 3D semi-automated change detection techniques such as the M3C2 algorithm, to estimate the volume of the rockfall.The results provide insights into the complex interplay between natural disasters and geological processes, shedding light on the dynamic nature of landscapes and the potential implications for visitor-preferred areas.This research not only contributes to our understanding of landscape evolution but also underscores the importance of integrating modern and historical datasets to decipher the dynamic processes shaping the Earth's surface. The methodology proposed, serves as a valuable approach for assessing and managing geological hazards in coastal regions affected by both climatic events and geodynamic activities.
High Resolution Soil Hydraulic Properties estimation from remotely sensed soil moisture time series.
Authors: Carles-Marqueño Robert , Perpinyà-Vallès Martí , Escorihuela Maria José
Published: March 2024

Accurate estimation of soil hydraulic properties, specifically field capacity (FC) and wilting point (WP), collectively known as Water Holding Capacity (WHC), is crucial for effective water resource management in agriculture and the environment. Traditionally, WHC is obtained through soil sampling and laboratory analysis. Pedo Transfer Functions (PTFs) have been developed to estimate WHC from soil composition data, simplifying the process but still relying on accurate soil measurements.In response, we propose a novel algorithm for dynamic FC and WP estimation based on continuous soil moisture time series from remote sensing. This study includes a preliminary accuracy assessment of the downscaled 100-m soil-moisture time-series obtained from a combination of SMAP and Landsat data against in-situ stations from the International Soil Moisture Network (ISMN) which also include WP and FC measurements. Leveraging these long time series of soil moisture data enables a more nuanced and adaptive characterization of soil hydraulic properties over time. This approach recognizes the influence of factors such as precipitation, evapotranspiration, and land management practices on soil moisture variability.Furthermore, we perform a comparative analysis with SoilHydroGrids’ WP and FC as a benchmark, to underscore the advancements, enhancements and potential limitations of our approach. Our results demonstrate a noteworthy enhancement in the estimation of Field Capacity, reducing the Root Mean Square Error (RMSE) from 0.15m³/m³ to 0.09m³/m³. Moreover, our algorithm exhibits slightly superior predictions for the wilting point when compared against laboratory measurements. Generally, our approach is capable of identifying a larger range of WP and FC values, which is also seen in the in-situ data.
Empirical Calibration of Contrail Models based on LIDAR Observations
Authors: Xu Michael , Meijer Vincent , Barrett Steven , Eastham Sebastian
Published: March 2024

Aircraft induced cirrus clouds are estimated to account for 57% of aviation’s current-day climate impact, but this value is highly uncertain with the fidelity and biases in meteorological data being significant contributing factors. Our work aims to address this uncertainty and to provide empirical evaluation of multiple contrail modeling approaches. First, we use a dataset of contrail cross sections observed from the CALIOP orbital LIDAR that were attributed to specific flights to calibrate parameterizations for the initial widths and depths of contrails. We then examine the effect of systematic biases in wind, humidity and temperature, analyzing which modifications to the data provide the best agreement between a simulated contrail (using the APCEMM contrail model) and observations. Finally, we evaluate the degree of accuracy of the calibrated APCEMM model across a larger dataset and compare the results to those from the widely-used CoCiP model. 
Temporal and spatial variability of the oceanic front between the Atlantic Water and adjacent water masses north of Svalbard
Authors: Vikanes Stian , Nilsen Frank , Skogseth Ragnheid
Published: March 2024

The inflow of warm Atlantic Water (AW) into the Arctic Ocean is controlled byoceanic fronts and air-ocean interactions north of Svalbard. The warm AW hasa significant impact on the sea ice extent and marine ecosystems in the region.Therefore, it is crucial to understand the variability of the oceanic fronts offshore andonshore of the AW, including their temporal and spatial characteristics, as well asthe mechanisms that govern them, such as atmospheric forcing, frontal instabilities,and advection. However, our current understanding of the variability of these frontsand AW north of Svalbard is limited due to lack of observational data. In this study,we will use historical and more recent hydrographic data to analyze and describesurface and subsurface fronts, both offshore and onshore of the AW core, in terms oftheir dominant water masses along the continental slope north of Svalbard. We willalso determine the strength and position of these fronts by examining the horizontalgradients in temperature, salinity, and density, and connect it to known changes inthe wind forcing.
Tectono-Geomorphic Studies along the Khetpurali Taksal Fault, Northwestern Himalayas
Authors: Narayana Poorvi , Mailk Javed N
Published: March 2024

The Northwestern Himalayas have been host to many earthquakes, with the recent 1905 Kangra Mw 7.8. Studies suggest the seismic gap in the Northwestern Himalayas to be more than Mw 7.8 in general, and of about Mw 8.4 in the Nahan region of the Northwestern Himalayas. There are studies suggesting the rupture of the Himalayan Frontal Thrust (HFT) and hinterland subsidiary faults by the Earthquakes in the region. In this study, we focused the Khetpurali Taksal Fault (KTF), which is one of the corroboration. It is an out-of- sequence ~ 250 km long dextral strike-slip fault with an NNW-SSE trend. KTF, which is bounded to the west by the Nahan Salient, and in the east by the Dehradun re-entrant; marks the boundary between the Central Himalayas (convergence rate ~ 18 ± 1 mm/y and obliquity ~0°) and the Northwestern Himalayas (convergence rate ~13.6–14 ± 1 mm/yr and obliquity ~ 15°-30°), which runs through the ~ 100km locked width of the Main Himalayan Trust (MHT). The dextral strike-slip motion has caused the displacement of some quaternary deposits along the KTF. It plays a key role in the slip partitioning between the active thrust and the oblique faults with the HFT displaying the thrusting and oblique component in the Pinjore Garden fault, Jhajra fault, and Barsar fault of the same region in the Northwestern Himalayas. This study is focused on the active fault along the KTF. We prepared the geomorphic map and delineated the extent of the KTF using the high-resolution Cartosat-1 data. Our studies show the presence of displaced terraces, lateral offset of streams, sag ponds, and pressure ridges along the KTF. A displacement of 250m to 1350m has been observed. Samples from the displaced terraces are analyzed by OSL dating technique to find out the slip along the KTF. Understanding the slip along KTF will enhance the understanding of slip partitioning taking place in the Nahan Region as a whole, which will help understand the geodynamics of the region and thus in seismic hazard assessment.
Human impact on groundwater levels: identification and quantification
Authors: Kokimova Ainur , Brielmann Heike , Birk Steffen
Published: March 2024

Groundwater is a crucial source of freshwater globally, sustaining agriculture, industry, domestic consumption, and the environment. Understanding the human-induced impacts on groundwater is vital, especially in regions threatened by quantitative and qualitative problems. Unfortunately, very often not all information on human activities that may affect groundwater is easily available. We, therefore, test a simple approach combining time series analysis and point detection to identify human impacts on groundwater. The time series models are built by using accessible climate data. In cases where a simulation does not perform well, multiple changepoint detection is applied to capture the time for a potential human impact event and its significance. The method is applied to two Austrian cities where disturbances caused by dam construction and pumping events were detected. The presented results illustrate the capacity to identify and characterize shifts in groundwater dynamics attributed to human interventions. Notably, the methodology proves effective in scenarios where extensive datasets are unavailable, providing a practical and reproducible means to comprehend human-induced alterations in groundwater resources.
Exploring Uncertainties Within a Framework for Assessing Extreme Precipitation-Induced Cascading Hazards in the Himalayas 
Authors: Dixit Sudhanshu , Subramanian Srikrishnan Siva , Sen Sumit
Published: March 2024

The Himalayas are increasingly vulnerable to the impacts of climate change, with recent years experiencing a surge in the frequency of natural hazards. The risk escalates when events unfold in a cascading manner, where a primary hazard triggers a secondary one. Therefore, it is crucial to develop an integrated framework to assess the ramifications of these cascading hazards. This framework plays a pivotal role in providing early warnings, considering the uncertainty introduced by rainfall input. The presented framework simulates the dynamic interplay between intense precipitation events and hill slopes, potentially triggering landslides. It subsequently models the debris flow resulting from the runoff formed by precipitation mixing with landslide deposits, culminating in debris runout. To address data uncertainties, the framework integrates four diverse precipitation data sources: gridded observation datasets, reanalysis data, satellite data, and numerical weather prediction models. The methodology assesses sediment volume originating from hillslopes and anticipates the sediment volume reaching river junctions during extreme events. Additionally, it involves the numerical simulation of the initial stages of the cascading nature of geohazards, specifically the transformation of landslides into debris flows. The framework's validation is conducted using the 2013 North India Floods, an extreme precipitation event that triggered over 6000 landslides and debris flows.
UAV placement of GNSS trackers on glaciers
Authors: Martinez Kirk , Hart Jane , Bragg Graeme , Attia Sherif , Baurley Nathaniel , Andrews Amelia
Published: March 2024

Commercially available UAVs can carry different types of payload such as cameras, Lidars and GPR. They also feature safety sensors such as collision awareness as well as mission planning with high accuracy RTK GPS. This makes them valuable tools to deploy sensors onto glaciers as long as the payload is within the maximum the UAV can carry.We have been installing sensor networks inside and under glaciers since 2003 (https://glacsweb.org). Our most recent projects designed an RTK GNSS system to measure ice movement on two glaciers in Iceland. They send the location fixes back to a server every day and have been made smaller as well as lighter in our most recent version. The units use a custom aluminium “quadpod” to stay securely on the glacier. This enabled us to investigate methods to deploy and collect them using a DJI Matrice 300. This quadcopter has a maximum payload of 2kg so we designed the system to meet that requirement. This involved testing a lighter frame structure and smaller GPS antenna than the original versions. However they maintained the same high capacity battery, electronics and 5W solar panel. By using a commercially available release and camera module (PTS4) we were able to use a roughly 2m chord to attach the unit underneath the UAV. Once the tracker was positioned and set down onto the ice, with constant monitoring of the downwards facing camera included in the PTS4, the release mechanism was triggered. This was first carried out first at Breiðamerkurjökull then at Fjallsjokull. The first flight of around 1300m was to an easily accessible area in case of placement issues. The second flight was to a central part of Fjallsjokull which is inaccessible due to crevasses.To test pick-up techniques, we investigated a range of hooks and grabbers as the combination of flight controls and logistics make it an interesting problem to solve. Our initial tests point to a hooking technique rather than a grabber and this aspect will be ongoing for tests of units on the glacier, which sink in a few centimetres when first placed in the summer.Tracker22 being lifted to Fjallsjokull
Modelling focused fluid flow in the subsurface: its controlling factors and the formation of seismic chimney 
Authors: Wang Lawrence Hongliang , Yarushina Viktoriya
Published: March 2024

Seismic chimneys, prevalent along continental margins, intricately contribute to Earth's degassing processes, facilitating fluid migration from the deep Earth to the surface. This phenomenon carries significant implications for subsurface storage utilization. Among the principal mechanisms driving seismic chimney formation is the fluid flow instability within porous subsurface rocks. While numerical studies of geodynamical two-phase flow have successfully replicated vertical fluid flow structures, many of these models overlook elastic compaction, advection of solid and poro-space, and geological heterogeneity, thereby limiting their applicability in subsurface scenarios. In addressing these limitations, this study incorporates a viscoelastic rheology into the geodynamical two-phase flow model to explore the controlling factors influencing the formation of focused fluid flow, accounting for various rock properties, including geological heterogeneity. Initial investigations into the impact of elastic compaction by varying Deborah numbers reveal a limited influence on fluid flow compared to viscous compaction. Through a comparative analysis of models with and without advection, we observe the potential importance of solid advection in fluid migration, particularly under conditions of high background porosity (≥0.1) and relatively low permeability. This effect is accentuated when the solid matrix undergoes significant deformation. Channel widths range from 2-3 compaction lengths to a maximum of 5-10 compaction lengths, primarily contingent on the viscosity ratio between shear and bulk viscosity and the fluid supply. Further simulations involving fluid flow encountering a horizontal block with rock heterogeneity and geological heterogeneity demonstrate the potential for fluid penetration through the structure or deflection to the side, contingent upon rock properties and block size. Finally, we apply our model to a specific seismic chimney at Loyal Field in Scotland, UK, successfully reproducing the observed upward-bending structure in the seismic image with a consistent width-height ratio. This comprehensive investigation sheds light on the complex interplay of various factors influencing focused fluid flow, including geological heterogeneity, thereby contributing valuable insights to the understanding of seismic chimney formation in real-world geological settings. 
Does this moraine constrain a Late Holocene readvance in the Amundsen Sea sector of the West Antarctic Ice Sheet?
Authors: Nichols Keir , Adams Jonathan , Brown Katie , McKenzie Marion , Venturelli Ryan , Goehring Brent , Johnson Joanne , Rood Dylan , Wilcken Klaus , Woodward John , Roberts Stephen
Published: March 2024

Following rapid ice thinning in the mid-Holocene, Pope Glacier (adjacent to Thwaites Glacier in the Amundsen Sea sector) was at least 30-35 m thinner than present for at least 3 kyr in the mid- to Late Holocene. The timing of the end of this ice lowstand and subsequent rethickening of ice to near its present configuration is poorly constrained. We present five paired 10Be and 26Al cosmogenic nuclide exposure ages that provide constraints on the timing of this ice sheet readvance. The ages are sourced from samples collected from a moraine
Petrological and textural characteristics of Garnet mica schists and Gneisses from Almora Group: Insights into pre-Himalayan metamorphism from Kumaun Himalaya, India
Authors: Srivastava Tanya , Joshi Mallickarjun , Kumar Alok , Tiwari Amar Nath , Patel Shubham
Published: March 2024

In Kumaun Lesser Himalaya, North Ramgarh Thrust and South Ramgarh Thrust define the northern and southern boundaries of the Almora Nappe. The Almora Nappe consists of two tectono-stratigraphic units, viz. the Ramgarh Group and the Almora Group. The Ramgarh Group consists of mylonitised granite gneisses capped by low-grade metamorphic rocks and the Almora Group consists of an interbanded sequence of metapelites and metapsammites progressively metamorphosed from the greenschist to upper amphibolite facies conditions. The Almora Group rocks comprise quartzites, garnet-mica schists, and K-feldspar–sillimanite gneisses. The garnet-mica schists are coarse to medium-grained, with well-developed foliation defined by chlorite-biotite-muscovite-garnet-plagioclase-quartz mineral assemblage, and the accessory minerals are apatite and zircon. The pelitic gneisses consist of garnet, kyanite, cordierite, sillimanite, and K-feldspar. Garnet is a common and important mineral in these metamorphic rocks to constrain P-T conditions.  In this study, we specifically focus on the textural details of garnets from the schists and gneisses of the Almora Group. The most common garnet is type II garnet which is synkinematic with S-shaped inclusions of quartz and biotite, while the older type-I garnets occur as stretched out grains in the matrix with the stretch direction generally parallel to the foliation. The garnet porphyroblasts are euhedral to subhedral and consist of quartz, plagioclase, muscovite, and apatite inclusions, which are wrapped around by muscovite and biotite lepidoblasts. The hematite leachings are observed around the periphery of the garnet porphyroblasts that suggest high fO2 in the last stages of garnet growth. The micas microfolded in a few samples, with the presence of quartz in the folded hinge region. The garnets can be classified into at least two generations based on textural and petrographic attributes. Moreover, the presence of an idioblastic rim in the garnets suggests that the later phase of metamorphism outlasted the deformation. The occurrence of two generations of garnet i.e. garnet within garnet documented by (Joshi & Tiwari, 2004; Joshi & Tiwari, 2009) suggests a hiatus in crystallization and the associated metamorphic processes are likely attributed to two generations of pre-Himalayan metamorphisms. 
Is Europe's Transportation Network ready to face Climate Change?
Authors: Deidda Cristina , Thiery Wim
Published: March 2024

Climate change impacts are evident across a wide range of society sectors. Extreme events like floods, heatwaves, and storms pose a significant threat to the Trans-European Transport Network (TEN-T), resulting in infrastructure damage, economic losses, and health issues for the population. Future projections indicate an elevated risk of coastal flooding for seaports and ports, along with heightened exposure of railways and roads to extreme temperatures. This escalating risk underscores the imperative for implementing effective adaptation measures to enhance the resilience of the entire transport network. Our analysis focuses on assessing the vulnerability of all modes within the European Core Network (airports, seaports, railways, roads, inland water) to climate-related extreme events. We examine the specific challenges and impacts on each transport mode, while also investigating the increasing exposure across different Representative Concentration Pathway (RCP) scenarios. 
Investigating the complementarity of thermal and physical soil organic carbon fractions
Authors: Delahaie Amicie ,   Freacs team
Published: March 2024

Evaluating SOC biogeochemical stability is key to better predict the impact of SOC on both climate mitigation and soil health. This evaluation can be conducted using SOC partition schemes that allow us to quantify SOC fractions with different biogeochemical stability. However, most of these schemes are costly or time consuming and cannot be implemented on large sample sets. Two exceptions are  the widely used physical fractionation protocol allowing to separate particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) and the emerging thermal fractionation protocol distinguishing active SOC (Ca; MRT ~30 years) from stable SOC (Cs; stable at a centennial timescale).Here, we use analyzes conducted on samples from the French soil monitoring network (RMQS) to compare the results of thermal fractionations (Ca/Cs) performed on ca. 2000 samples, and physical fractionations (POC/MAOC) performed on ca. 1000 samples. Our results show that MAOC and Cs from one side and POC and Ca from the other side have different sizes. The most biogeochemically stable fractions (Cs and MAOC) are mostly influenced by soil characteristics whereas land cover and climate influence more substantially POC and Ca. However, the more stable fractions provided by both fractionation schemes (respectively the more labile fractions) do not have the exact same environmental drivers. Our results therefore suggest that both fractionation scheme gives complementary results. The relative contribution of these fractionation schemes to the evaluation of soil functions and OC stock evolution remains to be evaluated on soil monitoring networks and constitutes a promising research avenue.
The origin of the Kupferschiefer mineralization (eastern Germany): constraints from petrography and analysis of stable sulfur isotopes of pyrite and chalcopyrite
Authors: Magnall Joseph , Liu Yang , Gleeson Sarah , Rocholl Alexander
Published: March 2024

The European Kupferschiefer Province contains multiple sediment-hosted stratiform copper (SSC) deposits and has been mined for many centuries. The mineralized rocks of the Kupferschiefer are stratabound and hosted by a stratigraphic succession of Late Permian terrestrial sandstones (Rotliegend Formation) and transgressive marine mudstones and limestones (Zechstein Formation). The formation of the Kupferschiefer deposits has been described by various genetic models, which primarily differ in terms of the timing of ore stage sulfide formation relative to host rock deposition (i.e. syn-genetic vs. epigenetic). In this study, samples from two drill cores in the Spremberg-Graustein Kupferschiefer deposit (eastern Germany) are described. Reflected light and scanning electron microscope (SEM) petrography has been used to determine key paragenetic relationships and in situ sulfur isotope values of pyrite and chalcopyrite (secondary ion mass spectrometry; SIMS) have been generated to determine pathways of sulfide formation. The extensive replacement of carbonate and feldspar by ore stage sulfides provides evidence that hydrothermal activity post-dated the formation of diagenetic phases in all units. The highly negative δ34S values of pyrite (–41.9‰ to –35.7‰) and chalcopyrite (–38.9‰ to –34.5‰) indicate that reduced sulfur was generated via open system organoclastic sulfate reduction (OSR). The indistinguishable δ34Schalcopyrite values preserved in the Rotliegend sandstones and Zechstein mudstones suggest a common origin of sulfides in distinct lithologies. To reconcile the petrographic evidence of host rock replacement with the isotopic evidence of open system sulfate reduction requires an external source of bacteriogenic sulfur, most likely in the form of a low temperature sulfur rich brine. The infiltration of low temperature brines transporting bacteriogenic sulfur is a key feature of genetic models in other sediment hosted systems (e.g., Irish Zn Ore Field). If this model is applied to the Kupferschiefer district, exploration programs should target subbasins with evidence of low temperature brine circulation from marginal sedimentary facies.
The Uncertainty of Temperature Predictions and the Influence of Flow Zones on the Production Temperature in a Low Enthalpy Geothermal Field
Authors: Schölderle Felix , Zosseder Kai
Published: March 2024

Besides the amount of a thermal fluid produced and its chemical composition, temperature is one of the key parameters for the utilization of hydrothermal heat. This applies in particular to geothermal fields with low temperature/low enthalpy, as too low extraction temperatures can mean the failure of a project, while higher temperatures can enable electricity generation or generally better economic efficiency. This concerns the undisturbed (natural) temperature in the reservoir as well as that of the produced fluid at the surface, which depends on the well completion, the undisturbed reservoir temperature, and the depth and contributions of hydraulically active zones. Subsequently, improved forecasts of both the undisturbed temperature and the production temperature with a valid estimate of their uncertainty are required to provide a reliable basis for field development and risk assessment.In the national projects Geothermal-Alliance Bavaria and KompakT, we studied the temperatures in the North Alpine Foreland Basin in Bavaria, Germany. The carbonate rocks form one of Europe’s most important reservoirs for the use of deep geothermal energy, and projects for district heating and electricity generation have been realized here for more than 30 years.We developed a good practice workflow for the correction of low-quality bottom hole temperature (BHT) values based on a probabilistic Monte Carlo approach. Using this workflow, we corrected BHTs from over 300 hydrocarbon and geothermal wells and predicted the natural temperature field inside the study area. The resulting temperature model is based on risk scenarios and contains a range of uncertainty, the extent of which depends on the uncertainty of the correction input parameters at the individual locations.To study the short-term and long-term thermal behavior in the reservoir and the wellbore during production conditions, in 2019, a fiber optic cable was installed below the pump into the reservoir of a geothermal production well. We used distributed temperature sensing (DTS) to observe the hydraulically active zones and to thermally derive their contribution to the available heat amount.The knowledge gained underlines the importance of flow zone characterization and can be used to improve existing temperature models and estimate what temperatures can really be expected during extraction.
Economics of hybrid pumped hydropower storage in open-pit coal mines: a case study for the Greek energy market
Authors: Otto Christopher , Ernst Priscilla , Roumpos Christos , Louloudis Georgios , Mertiri Eleni , Kempka Thomas
Published: March 2024

A dynamic techno-economic simulation model was developed in the present study to assess the capital and operational expenditures (CAPEX and OPEX) as well as economic benefits of a prospective Hybrid Pumped Hydropower Storage (HPHS) installation to be realised in a Greek open-pit coal mine. HPHS is not only limited to store excess energy produced by local renewable energy sources, i.e. photovoltaic and wind farms, but can also be applied to store of excess energy from the grid. The model accounts for losses incurring while charging the upper reservoir with water when excess energy from renewables and the electric grid is available as well as discharging the upper reservoir for electricity generation when the national electricity demand exceeds the energy provided by the grid. A charging and discharging scheme for the HPHS installation was dynamically calibrated by means of historic energy market data, including time-dependent national energy balances and electric grid costs. Revenues, expenditures and profits of the prospective HPHS implementation were calculated, and the key economic parameters Net Present Value (NPV), Internal Rate of Return (IRR) and Discount Payback Period (DPP) determined to account for the overall system profitability during its’ entire operational time. The model’s technical implementation and applicability for system performance optimisation are discussed in detail, especially in view of a profit-maximising energy storage scheme, which was developed and applied to stochastic grid cost development predictions to account for the HPHS installation’s potential future benefits. The model can be integrated with online real-time data to economically schedule HPHS operation in highly dynamic energy systems.The present study has received funding from the Research Fund for Coal and Steel—2020, under grant agreement No. 101034022 (ATLANTIS).
An historical flash drought analysis in Sicily based on ERA5 Reanalysis evapotranspiration and soil moisture data
Authors: Aschale Tagele Mossie , Buonacera Gaetano , Palazzolo Nunziarita , Cancelliere Antonino , Peres David. J
Published: March 2024

Sicily copes periodically with the challenge of drought events, impacting water resources management, as well as agricultural and environmental landscapes. While the area is well studied regarding traditional slow-evolving droughts, studies on flash droughts are lacking. This study delves into the historical analysis of flash drought events in Sicily, characterized by their abrupt onset and severity.  Specifically, we carry out our analysis based on ERA5-Land Reanalysis daily evapotranspiration and soil moisture data, covering the period 1950-2023. First, a comparison of ERA5-Land Reanalysis evapotranspiration with reference evapotranspiration computed from observational series is carried out. Then the Evaporative Demand Drought Index (EDDI) is computed from the Reanalysis evapotranspiration series, at various temporal scales. The EDDI index is then analysed in combination with soil moisture series at various soil depths, to corroborate the identification of the onset of past historical flash drought events. A specific focus in devoted to a heat wave occurring during July 2023, showing the severity of this event. The study provides preliminary insights for a clearer development of criteria for flash drought identification in the Mediterranean area.  
Science goals of the COMPASS instrument consortium on M-MATISSE
Authors: Andrews David , Futaana Yoshifumi , Henri Pierre , De Keyser Johan , Píša David , Platschke Ferdinand , Rothkaehl Hanna , Štverák Štěpán
Published: March 2024

Mars–Magnetosphere ATmosphere Ionosphere and Space-weather SciencE (M-MATISSE) is a candidate for the ESA M7 mission opportunity, currently being studied by ESA in Phase A.  It consists of two spacecraft with largely identical scientific payloads that will be placed into orbit around Mars in 2037.  On inclined elliptical orbits they will encounter all relevant regions of the Mars-induced magnetosphere and upper atmosphere for further refining our understanding of the exchange of material, energy and momentum between the solar wind and space environment, and the Martian system. The Combined Magnetic and Plasma Sensor Suite, COMPASS, consists of dual Fluxgate Magnetometers (MAG), dual Langmuir Probes (LP), a Mutual Impedance eXperiment (MIX) (composed of an electronic card Mutual Impedance Board (MIB) that supplies driving electric signals to the Mutual Impedance Probe (MIP)) and a 3D Velocity of Ion (3DVI) instrument (composed of Ion Drift Meter (IDM) and a Retarding Potential Analyzer (RPA) in a combined instrument package), with redundant integrated Wave Analyzer Processing Unit (WAPU) for handling digital data processing and redundant Low Voltage Power Supply (LVPS). Design heritage for COMPASS is derived from the Dust and Fields Package to be flown on Comet Interceptor and from the Radio And Plasma Wave Investigation on the Jupiter Icy Moons Explorer. By sharing physical and electrical resources where possible, COMPASS provides an integrated suite of sensors and data handling systems that will provide highly configurable measurements of plasma properties (density, temperature, velocity and basic composition), as well as the vector magnetic field, a single component of the electric field, and the spacecraft potential. In this presentation, we will review the initial design, expected performance and scientific goals of the COMPASS consortium within the M-MATISSE mission.
Modelling and evaluating GLOF risk management measures in the Kyrgyz Ala-Archa valley
Authors: Niggli Laura , Zaginaev Vitalii , Frey Holger , Allen Simon , Huggel Christian
Published: March 2024

Glacier lake outburst floods (GLOF) are mass flow hazards of severe destructive potential and far reach that can cause extensive damage to the natural and built environment posing a threat to people and their livelihoods. Diverse risk management measures have been proposed and been implemented in order to reduce the risks associated with GLOFs. However, systematic studies on the effectiveness and cost-benefit of such measures in the contest of disaster risk management (DRM) are largely lacking.Here we model, map and evaluate GLOF risk measures and analyse how the implementation of different GLOF DRM measures alters GLOF risk. We compare cost and benefit of five potential measures in the mountainous Ala-Archa catchment in the Kyrgyz range south of Bishkek, the capital of the Kyrgyz Republic. Using the RAMMS debris flow software, the extent of two GLOF scenarios are modelled for the situations of (i) no DRM measure (current state), (ii) lake volume reduction, (iii) a deflection dam, (iv) a retention dam and reservoir, (v) an Early Warning System, and (vi) land use planning.We analyse the effect of the different DRM measures by examining the three components of risk, namely hazard, exposure and vulnerability. We estimate the expected cost of the respective DRM measures and compare it to the costs of the potential damage caused by the GLOF scenarios. While we assess hazard and exposure quantitatively, we analyse vulnerability in a qualitative way, based on socio-economic characteristics such as age, gender, education, economic diversity and dependency.With increasing numbers of glacier lakes and potential disastrous lake outbursts linked to climate change, often combined with increasing exposure of infrastructure and human assets, cost effective GLOF DRM is of growing importance.  While the absolute numbers based on the exposed assets, cost and damage will differ for other settings, the conceptual approach of this case study can be applied to other mountainous catchments. This study’s main findings serve as a basis for decision making in similar settings with stakeholders aiming for cost-effective GLOF risk management.
Cryosphere, Causality, and Couplings of Ocean and Atmosphere: The Secrets of Himalayan Snow
Authors: Sengupta Shairik , Das Bhowmik Rajarshi
Published: March 2024

The Himalayas host some of the most sensitive parts of the cryosphere. Fast and ill planned development proves to be ill-fated, for both the cryosphere and its many human neighbors. The complex geography of the region poses a challenge not only to ground based observations, but also to understanding the processes driving the cryosphere and modeling its behavior. In this study we focus on the western Himalayas. An examination of precipitation of the region through regression, wavelet analysis, and machine learning suggested various climate indices indicative of ocean atmosphere coupling states to be drivers of snow cover. Seasons and sub regions show variation in sensitivity to these remote forcings. Finally, causal inference is employed to establish teleconnections as drivers and predictors of snow fall and snow cover.
Geographic Object-Based Image Analysis (GEOBIA) for inventory mapping of forest-covered landslides: a case study in Jena, Germany
Authors: Zangana Ikram , Bell Rainer , Drăguţ Lucian , Schrott Lothar
Published: March 2024

For assessing landslide susceptibility and hazard reliable landslide inventories are essential. Historic landslides might indicate periods of increased landslide activity compared to more recent decades. However, landslide features might have diminished over time especially due to human impact. Often features of historic landslides are well preserved under forest providing a valuable source for preparing or completing landslide inventories, but mapping them is challenging.Analyzing Light Detection and Ranging (LiDAR) and its derivatives have become powerful tools in landslide research, particularly in the identification and mapping of landslides. In contrast to the expert-based analysis of LiDAR derivatives, there is a limited number of studies employing object-based approaches to (semi)automatically mapping landslides from LiDAR data. This study focuses on the use of Geographic Object-Based Image Analysis (GEOBIA) based solely on LiDAR derivatives (1 m resolution) to conduct inventory mapping of forest-covered landslides within a middle mountainous region in Germany.The study centers on Jena and its surrounding areas in Germany, covering an approximate area of 150 km². As part of the Thuringia basin, the study area is dominated by two major geological formations. The Muschelkalk  (limestone) covers the majority of the upper parts of the slopes and the plateau areas. It is underlain by the Buntsandstein  (marls, claystone and sandstone). Large landslides are historic and covered by forest. The methodology incorporates an inventory map for the purposes of module training and validation. LiDAR derivatives, encompassing slope, plan curvature, Terrain Roughness Index (TRI), Terrain Position Index (TPI), and differential openness, are systematically applied across diverse scales to identify landslide scarps and bodies within distinct window sizes. This systematic approach is further complemented by multi-resolution segmentation at multiple levels, support vector machine (SVM), rule-based classification, GEOBIA-based refinements, and a rigorous accuracy assessment. Collectively, these components establish a comprehensive framework for the progression of landslide detection and mapping methodologies.The results reveal that the proposed approach achieved an 80% detection rate compared to the expert-based inventory. Nevertheless, continuous efforts are being made to reduce the occurrence of false positive detections. While the module demonstrates proficiency in identifying and mapping historical forest-covered landslides, its current functionality is limited to recognizing and mapping large and medium-sized landslides [area > 0,5 ha]. The transferability of this module should be evaluated in other regions. We anticipate that globally landslides with clear geomorphological signatures in high-resolution Digital Terrain Models (DTMs) can be identified using this approach.
A machine learning model for the vertical correction of tropospheric zenith delays
Authors: Yuan Peng , Balidakis Kyriakos , Wang Jungang , Deng Zhiguo
Published: March 2024

Tropospheric delay is one of the most important error sources for space geodetic techniques, such as the Global Navigation Satellite Systems (GNSS). A priori tropospheric Zenith Hydrostatic and Wet Delays (ZHD and ZWD) should be obtained properly in advance to the GNSS data processing. Numerical Weather Model (NWM) is capable to provide accurate tropospheric zenith delays at any specific location with sophisticated calculation. As a more convenient alternative, the tropospheric zenith delays can be first modeled with NWM as a 2-D grid on the Earth surface and then corrected to the height of the specific location. In this case, accurate vertical correction algorithm is crucial. However, though empirical analytical models have been developed for the vertical correction of tropospheric zenith delays, their accuracies are limited due to the large spatiotemporal variability of the delays. In this work, we propose a Machine Learning (ML) model based on neural network for the vertical corrections of both ZHD and ZWD. The training data is obtained from the state-of-the-art NWM, the fifth-generation global reanalysis of European Centre for Medium-Range Weather Forecasts (ERA5). The proposed ML model is capable to reconstruct the tropospheric delays at any height from the Earth surface to up to 14 km. The precision of the ML model is superior to the analytical models with global average RMS values less than 2 and 3 mm for ZHD and ZWD, respectively. Therefore, it provides a convenient alternative to the sophisticated vertical integration of NWM for ordinary users with slight precision loss.