bluuebunny/crossref_metadata_2025 huggingface dataset:
TEC variation over Europe during the intense tectonic activity in the area of SE Turkey on February of 2023.
Authors: Contadakis Michael E. , Pikridas Christos , Bitharis Styllianos , Scordilis Emmanuel
Published: March 2024

This paper is one of a series of papers dealing with the investigation of the Lower ionospheric variation on the occasion of an intense tectonic activity.In the present paper, we investigate the TEC variations during the intense seismic activity in the transition between the Dead Sea fault and the East Anatolian fault (SE Turkey) on February 6th, 2023. The Total Electron Content (TEC) data are been provided by the EUREF Network. These data were analysed using Discrete Fourier Analysis in order to investigate the TEC turbulence band content. The results of this investigation indicate that the High-Frequency limit fo of the ionospheric turbulence content, increases as aproaching the occurrence time of the earthquake, pointing to the earthquake epicenter, in accordane to our previous investigations. We conclude that the Lithosphere Atmosphere Ionosphere Coupling, LAIC, mechanism through acoustic or gravity waves could explain this phenomenology. Keywords: Seismicity, Lower Ionosphere, Ionospheric Turbulence, Brownian Walk, East Anatolian Fault. 
Modelling the isotopic signatures of solutes derived from weathering reactions
Authors: Druhan Jennifer , Benettin Paolo
Published: March 2024

High-resolution water chemistry records in rivers typically show that the routing of reactive solutes through the Critical Zone is a dynamic process that can change drastically across hydrologic responses. Quantitative transient models are needed to interpret these riverine solute measurements as emergent signatures of coupled geochemical and ecohydrological functioning. In this context, the stable isotope signatures of geogenic solutes offer a unique opportunity to disentangle processes such as the dissolution or primary minerals, precipitation of secondary phases and ecological nutrient cycling. Here, we describe the first merging of a parsimonious hydrological model featuring time-variant fluid age distributions with a geochemical model for isotopically fractionating weathering reactions. Using SiO2(aq) and the corresponding silicon isotope ratio δ30Si as an example, we show that the stable isotope signatures of riverine solutes produced by weathering reactions reflect a component of the fluid age distribution that is unique to the corresponding solute concentrations. This distinct sensitivity offers a novel diagnostic tool to interpret the SiO2(aq) and δ30Si dynamics recorded in six low-order streams spread across a diversity of climates, geologies, and ecosystems.
A wet or dry European and Northern African climate during the Miocene Climatic Optimum
Authors: Acosta R. Paul , Burls Natalie , Pound Matthew , Bradshaw Catherine , Feakins Sarah
Published: March 2024

End-of 21st Century hydroclimate projections suggest an expansion of the subtropical dry zone, with Europe and Northern Africa becoming drier. However, paleoclimate evidence primarily from paleobotanical assemblages from a past warm climate period, the Miocene Climatic Optimum (MCO) ~14-17 Ma, suggests both regions were instead wet and humid environments. Here, we simulate the MCO with the Community Earth System Model (CESM 1.2) forced by compiled sea surface temperature (SST) proxy data that are 5-6°C warmer than Preindustrial in the North Atlantic (NA). Given these boundary conditions, the climate model better matches paleobotanical proxy evidence for wetter continents relative to coupled simulations. The prescribed SST simulations show enhanced ocean evaporation and integrated water vapor flux that overrides any drying effects associated with warming, increasing evaporation on land. The vegetation model (BIOME4) forced by the climatologies from our simulations predicts a mixed forested landscape dominated Europe and Northern Africa during the MCO, with largely consistent paleobotanical evidence. This proxy-model study of MCO climate reveals the potential for wetter Mediterranean climates associated with warming and presents an alternative scenario from future drying projections. The critical difference identified in our MCO simulations is localized SST warming governing regional climate.
Discovering the Critical and Strategic Raw Materials potential of historical mining dumps of Sardinia 
Authors: Sedda Lorenzo , Attardi Antonio , De Giudici Giovanni , Naitza Stefano
Published: March 2024

Modern society bases its economic and industrial development on the use of advanced technologies, which are produced using materials and metals defined in the European Union as critical and strategic raw materials about the risk of their supply, linked to geological and geopolitical factors, and their relevance for the European chain of value. The CRM Act approved by the European Parliament addresses the future policies on CRM and SRM of the Member States, particularly for the development of primary (mining) and secondary (recycling) sources of these materials. In the context of recycling policies, particular emphasis is given to the necessary evaluation of the potential of waste from past extractive activities. 
As a part of the wider Project Geoscience IR coordinated by the Italian Institute for Environmental Protection and Research (ISPRA), the University of Cagliari (UniCa) is carrying out a study on Sardinian mining dumps, which provides for their mapping and characterization through sampling and laboratory activities, to investigate their possible content in CRMs.
The first studies focused on SW Sardinia districts, have produced encouraging results, with the identification of the presence of CRMs in different types of wastes of various localities. The first target area is that of Montevecchio, once one of the largest mine districts in Italy, which now hosts over 13 million cubic meters of mining and processing wastes from the exploitation of a large Pb-Zn hydrothermal vein field. The study highlighted the economic potential of some of these materials, rich in Zinc (2.6%), Lead (1%) and Rare Earth Elements (about 600 ppm). In the south of Montevecchio, a second area of inferred high potential is the Fluminese region, marked by several kinds of CRM-bearing hydrothermal ore deposits. In this area, the mine dumps of the old Santa Lucia fluorite-barite mine are currently under study. Apart from fluorite and barite, they are suspected to host Ni-Co minerals and some amount of REE, given the wide chromatic variety of fluorites and the presence of Agardite-Ce in the mineralization. A third target under study is the Sulcis district, a historical mining area with numerous mine dumps scattered over a wide territory. Among them, of particular interest are the wastes related to the exploitation of Fe (magnetite) and Pb-Zn-Cu sulfide skarn ores, often marked by W and Sn contents.
The goal of the Project is to produce a database containing information on CRMs contents in the various Sardinian historical mining dumps, and a new metallogenic map of Sardinia that may include the waste deposits of possible economic interest, which were not reported in the two previous produced editions. The map will constitute a model for broader mapping of Italian resources at a national scale.
Keywords: Sardinia, mining dumps, critical and strategic raw materials, environmental sustainability
 
Relationships between growing cloudy updrafts, deep convection initiation, and orographic flow
Authors: Marquis James , Varble Adam , Feng Zhe , Jo Enoch , Gustafson William
Published: March 2024

Shallow cumulus cloud fields often organize and deepen within regions of mesoscale ascent associated with orographic flows. However, there is significant uncertainty in the relative roles of mesoscale and cloud-scale factors ultimately controlling the location of orographic deep convection initiation (DCI). These factors include spatial heterogeneity of the magnitude of mesoscale vertical mass flux associated with orographic convergence, near-cloud convective ingredients (e.g. CAPE, CIN, LFC, and shear), and entrainment effects. More fundamentally, it is not well understood how these factors influence the initial width and strength of low-level cloudy updrafts, which are increasingly cited as important governors of their ultimate depth potential. Thus, it is important to better understand these relationships for increased predictability of DCI. Numerous DCI events observed along the Sierras de Córdoba range during the Cloud, Aerosol, and Complex Terrain Interactions (CACTI) project were modeled by the U.S. Department of Energy’s LES ARM Symbiotic Simulation and Observation (LASSO) team. In this study, we examine the connection between low-level cloudy updrafts, DCI, and the ascent associated with the mesoscale orographic circulation using LES with 100-m and 500-m grid spacing across multiple days. We hypothesize that the width and strength of low-level cloudy updrafts and the probability of DCI events along the ridge are proportional to the width, strength, and depth of the local orographic convergence. To test this, we examine correlations between the width and depth of developing cloudy updrafts and the: i) 3D structure of the evolving orographic ascent, and ii) convective meteorological ingredients (e.g., convective available potential energy, convective inhibition, level of free convection, moisture, etc.). Preliminary results indicate that DCI events do not always occur in regions of the strongest or widest orographic ascent along the mountain range. Further, the strength and width of low-level cloudy updrafts that precede DCI are only weakly correlated with most orographic ascent metrics. Overall, the apparent relative roles of mesoscale ascent and convective sounding parameters governing DCI varied significantly across case days. Near-cloud relative humidity located near and just above the level of free convection steadily increased with time during each afternoon, likely owing to orographic vertical moisture flux and/or cloud detrainment. Thus, in addition to highly varied roles of the background conditions, the fate of individual growing cloudy updrafts may further depend on complex cloud-scale factors, such as entrainment and microphysical processes.
Tropical cloud feedback in near-Snowball Earth waterbelt states
Authors: Hörner Johannes , Voigt Aiko
Published: March 2024

Waterbelt states are an alternative scenario for Snowball Earth, where a narrow strip of ocean remains ice-free at the equator, providing a robust solution for the survival of life. Recent studies have shown that waterbelt states can be stabilised by subtropical low-level clouds, because they weaken the ice-albedo feedback created by the expanding sea ice beneath the clouds. Thick subtropical clouds are therefore needed to stabilise the waterbelt state.However, clouds also have the opposite effect over the open ocean equatorward of the ice margin. Here they provide a destabilising cloud feedback that supports the ice-albedo feedback in favour of a Snowball Earth. When sea ice enters the subtropics, this effect becomes particularly strong, as the vertical structure and the phase partitioning of tropical clouds begin to change. As a result, tropical clouds can ultimately determine the stability of the waterbelt state.Here we show a preliminary analysis of simulations with two versions of the atmospheric ICON model using the same setup, a slab-ocean aquaplanet with a thermodynamic sea-ice model and over a broad range of atmospheric CO2 concentrations. While waterbelt states are easily found in ICON-A, they are absent in ICON-ESM due to a difference in tropical clouds. The tropical cloud feedback will be analysed by means of cloud controlling factors, and simulations with the cloud locking method will be employed to demonstrate the critical role of tropical cloud feedback for waterbelt states. 
Stress transfer and poroelastic mechanisms to elucidate seismicity triggered by reservoirs
Authors: Andrés Sandro , Santillán David , Santoyo Miguel Ángel , Cueto-Felgueroso Luis
Published: March 2024

Induced seismicity has attracted increasing research interest in recent times. This phenomenon is generally associated with fluid injection or extraction wells, in energy industry activities such as hydrocarbon extraction/injection, CO2 sequestration, geothermal energy or underground storage of green hydrogen. However, there are other human activities that can induce or trigger seismic events, such as oscillations in the surface water level due to the construction of hydraulic infrastructures.Surface water level oscillations, whether natural or anthropogenic, can alter the pore pressure regime in the subsurface. Although these alterations usually have a moderate magnitude, they can destabilize faults that were already close to overcoming their slip resistance and eventually trigger an earthquake. On the other hand, the fault slip itself alters the pressure regime due to the undrained response of the porous medium, caused by the sudden deformation of the fault surrounding area. This undrained pressure, which can take up to weeks to dissipate, can alter the stress state of other nearby fractures and trigger new earthquakes or aftershocks.In this work we present numerical simulations of the underground area around the Itoiz dam (Spain). We simulate the subsurface as a saturated poroelastic medium, with a fully coupled scheme between fluid flow and solid deformation in the porous medium. Through a seismological analysis we start from series of recent earthquakes to locate geological faults. With our numerical model we study how the undrained effect produced by this series of events can destabilize other nearby faults. We also add the effects of the oscillations in the reservoir level following the historical series of the last years.Our numerical simulations indicate that in the case of the Itoiz dam, the most recent seismic swarm could have been triggered by the stress transfer from the previous events, which, together with the filling of the reservoir, may have destabilized faults that were critically stressed for failure. Our simulations can contribute to explore how the combined effect of the undrained pressure by the fault slip and the oscillations of the reservoir can trigger faults that, due to the natural state of stress, are already close to slip. Also to clarify if the most relevant mechanism is the oscillation of the reservoir level or the undrained pressure trigger, which according to bibliographic analysis can be of the same magnitude. This could apply to other cases of seismicity induced by hydraulic infrastructures or in general by oscillations in the surface water level.AcknowledgementsThis research Project has been funded by the Comunidad de Madrid through the call Research Grants for Young Investigators from Universidad Politécnica de Madrid under grant APOYO-JOVENES-21-6YB2DD-127-N6ZTY3, RSIEIH project, research program V PRICIT.
Drivers of soil carbon emission in warmed tropical soil
Authors: Nottingham Andrew , Bååth Erland , Broders Kirk , Meir Patrick , Montero-Sanchez Maria , Saltonstall Kristin , Sanjur Alicia , Scott Jarrod , Velasquez Esther
Published: March 2024

Soil microbes form some of the most diverse biological communities on Earth and are fundamental in regulating the terrestrial carbon cycle. Their response to climate warming could therefore have major consequences for future climate, particularly in tropical forests where high biological diversity coincides with a vast store of soil carbon. We used an in-situ soil warming experiment to test the response of tropical forest soil microbial communities, growth, enzyme activities and respiration to three years of soil warming. We first determined the response to warming of the microbial community composition and asked whether community change was related to a change in the intrinsic sensitivity of microbial growth. Second, we asked whether the response to warming of microbial growth sensitivity could explain the response of heterotrophic soil CO2 emission under in situ warming. The experiment, SWELTR (Soil Warming Experiment in Lowland TRopical forest) consists of five pairs of circular control and warmed plots (whole-profile warming, using buried resistance cables) distributed evenly within approximately 1 ha of semi-deciduous moist lowland tropical forest on Barro Colorado Island, Panama. Each warmed plot is heated across the full soil profile, resulting in a total of 120 m3 of warmed soil for the experiment. For this study we established two subplots per treatment plot that differed with distance to the heating source, thus providing two treatments of, on average, 3ºC and 8ºC warming of surface soils and performed field campaigns during the wet season (when soil moisture was not limiting to microbial activity). Microbial diversity declined markedly, especially of bacteria. As the microbial community composition shifted under warming, many taxa were no longer detected and others, including taxa associated with thermophilic traits, were enriched. The activity of 7 out of 10 measured soil enzyme activities increased with warming. The community shift resulted in an adaptation of growth to warmer temperatures, which we used to specify a microbial model to predict changes in soil CO2 emissions. However, the observed in situ soil CO2 emissions increase exceeded the rates predicted by our model three-fold. Our results show that the soil microbial community and growth response to warming was decoupled from large increases in CO2 emission, which was potentially boosted by an abiotic effect of warming on soil enzyme activity. Our results suggest that warming of tropical forests will have rapid, detrimental consequences both for soil microbial biodiversity and future climate.
The excitation of free core nutation: a reappraisal
Authors: Kiani Shahvandi Mostafa , Schindelegger Michael , Börger Lara , Mishra Siddhartha , Soja Benedikt
Published: March 2024

Free Core Nutation (FCN) is a rotational normal mode of the Earth arising from the misalignment of the rotation vectors of the mantle and the fluid outer core. There has long been suggestive evidence that this mode is excited against dissipation by variations in Atmospheric and Oceanic Angular Momentum (AAM and OAM, respectively), but efforts to reconcile model-based AAM and OAM estimates with the FCN in geodetic data (the Celestial Pole Offsets, CPO) have remained futile. In particular, prior assessments suggest that the power of geophysical excitation from AAM/OAM data exceeds the power of geodetic excitation at the FCN frequency by a factor of 10 or more. Here we reassess the geophysical excitation of FCN using 3-hourly AAM and OAM series from two latest-generation atmospheric reanalyses and consistently forced ocean forward models, called MERRA-2. We focus on the pressure terms and transform them to the celestial frame by complex demodulation. In addition, we use the latest CPO series of the International Earth Rotation and Reference Systems Service (IERS 20 C04) and convert it to geodetic excitation using a digital filter based on the broad-band Liouville equation. By filtering the geodetic and geophysical excitation series near the FCN frequency band (approximately –440 to –420 days in the celestial frame) we show that the agreement between these two series is improved relative to previous studies, such that the ratio of the power spectrum of geophysical to geodetic excitations is ~4.6. Moreover, we find clear similarities between observed and modeled (excitation) time series in the FCN band. Among the different drivers, the impact of AAM is at least 3 times larger than that of OAM. Our results represent progress in finding the cause of continuous FCN excitation, which is most probably the variability of atmospheric pressure over continental landmasses.
Large impacts and their contribution to the water budget of the Early Moon.
Authors: Engels Tristan , Monteux Julien , Boyet Maud , Bouhifd Ali
Published: March 2024

The Earth/Moon system likely results from a giant impact between a Mars-size object and the proto-Earth 70 to 110 Myrs after the formation of the first solids of the Solar System. This high-energy context leads to extreme conditions under which volatile elements would not normally be preserved in the protolunar disk. However, recent measurements of lunar samples highlight the presence of a significant amount of water in the Moon's interior (1.2 to 74 ppm). The aim of the present work is to quantify the water contribution of the late accretion on the early Moon. Here, we use a 2D axisymmetric model with the hydrocode iSALE-Dellen to study the fate of a large impactor on a target body similar to the early Moon with a crust, a magma ocean, and a mantle. For this purpose, we compute different models to monitor the depth to which the impacted material is buried at the end of the impact event and the degree of devolatilisation of the impactor. Three parameters are explored: the crustal thickness (ranging from 10 to 80 km), the impactor radius (ranging from 25 to 200 km) and the impactor velocity (ranging from 1 to 4 times the target escape velocity). Our models show that impactors with a radius greater than 50 km impacting a partially molten lunar body with a crust thinner than 40 km could significantly contribute to the water content of the lunar mantle even for impact velocities of less than 5 km s-1. For larger impact velocities (≥ 10 km s-1) the impactor material is significantly molten and its water content is devolatilised within the lunar atmosphere. Depending on the water content of the impactor material and the ability of the lunar magma ocean to maintain chemical heterogeneities, the late lunar accretion following the Moon-forming giant impact could explain the differences in water content between the lunar samples.
Seismological analysis of the September 16, 2023 Greenland landslide triggering a 50 hours long monochromatic very long-period signal
Authors: Carrillo-Ponce Angela , Petersen Gesa , Cesca Simone , Heimann Sebastian , Walter Thomas R. , Dahm Torsten
Published: March 2024

On September 16, 2023, a landslide collapsed in the Dickson Fjord, a remote area of East Greenland. The collapse triggered a tsunami that hit Ella Island, which lies to the east of the fjord. The mass movement is identified in high resolution Planet Labs Dove mini-satellite imagery, and the generated seismic signals were recorded at both regional and teleseismic distances. The seismic records reveal a first strong transient signal (0.02-0.06 Hz) around 12:35:00 UTC, which we attribute to the landslide, followed by a long-lasting (~50 hours) monochromatic (~0.01 Hz) signal at teleseismic distances. We perform full waveform inversions using moment tensor and single force models to characterize the source of both signals. At regional distances, the first transient signal is well reproduced by single and double source models and is consistent with the landslide process. The long-lasting oscillation is modeled by a damped dipole oscillator, which is in agreement with the Love and Rayleigh waves radiation patterns observed at different azimuths. Using multiple different data and source models we are able to characterize the complex source process.
Detailed clustering of continuous seismic waveforms with deep scattering networks: a case study on the Ridgecrest earthquake sequence
Authors: Esfahani Reza , Campillo Michel , Seydoux Leonard , Mouaoued Sarah , Wang Qing-Yu
Published: March 2024

Clustering techniques facilitate the exploration of extensive seismogram datasets, uncovering a variety of distinct seismic signatures. This study employs deep scattering networks (Seydoux et al. 2020), a novel approach in deep convolutional neural networks using fixed wavelet filters, to analyze continuous multichannel seismic time-series data spanning four months before the 2019 Ridgecrest earthquake sequence in California. By extracting robust physical features known as scattering coefficients and disentangling them via independent component analysis, we cluster different seismic signals, including those from foreshock events and anthropogenic noises. We investigate the variability of intracluster (dispersion within each cluster) and examine how it correlates with waveform properties and feature space. The methodology allows us to measure this variability, either through distance to cluster centroids or 2D manifold mapping. Our findings reveal distinct patterns in the occurrence rate, daily frequency, and waveform characteristics of these clusters, providing new insights into the behavior of seismic events versus anthropogenic noises.
Challenges to implement an open, free, participative gravity-modelling initiative
Authors: Hetényi György , Scarponi Matteo , Baron Ludovic
Published: March 2024

In January 2024, our team has launched an open, free, participative gravity-modelling initiative. The idea is to provide all the necessary, pre-processed input data to the community, so that modelling and inversion can be applied by anyone interested in constraining the shape of a geological-geophysical anomaly. This way we hope to step over hurdles related to personal biases. The full description can be found at https://zenodo.org/records/10390437Beyond advertising the initiative, we would like to share some thoughts on the pathway to launching it: the motivation, the interest, the experienced past difficulties and further challenges on the horizon. By doing so, we hope to contribute to the goals of this session, and to foster further such (scientific and sharing) initiatives.
Spatiotemporal structure of raindrop size distribution due to flow field in a convective precipitation system simulated by bin cloud microphysics model.
Authors: Okazaki Megumi , Yamaguchi Kosei , Yanase Tomoro , Nakakita Eiichi
Published: March 2024

Precipitation droplets are influenced by environmental fields and transform in time and space, following cloud microphysical processes. Accordingly, a raindrop size distribution (DSD) changes shape in a various form. However, DSDs cannot be calculated directly in radar or bulk models and are expressed using an approximate function. Exponential and gamma distribution are well-known as approximation functions, but there are DSDs of shapes that cannot be represented by these functions. One of them is a bimodal DSD with two peaks. Previous modeling studies have indicated that the bimodal DSD is formed when the collision-breakup process reaches equilibrium. On the other hand, recent observation-based studies have discussed the influence of convective activity within the precipitation system on forming the bimodal DSD. However, observations have not been able to quantitatively study the microphysical changes of individual particles and have yet to reveal the formation mechanisms within the precipitation system. In this study, we investigated quantitatively the process of the formation of the bimodal DSD by two-dimensional simulation of multicellular convection with the bin method. The simulation results showed that the bimodal DSD was formed during the updraft and downdraft in the mature stage of the multicell. Additionally, the bimodal DSD was formed at lower altitudes where there was inflow into the precipitation system. Particles that constituted the maximum of the bimodal DSD were found to have been advected by the inflow. Particles that constituted the local maximum dropped against the updraft. In contrast to these, particles that constituted the local minimum were less affected by the inflow and had difficulty dropping against the updraft. These results suggested that the bimodal DSD was formed by horizontal and vertical size sorting because of inflow and updrafts in the mature multicellular convection. In the future, it is necessary to simulate the reproduction of observed cases and compare them with observations.
Fractures versus flow: How variations in carbonate composition control the rheology of altered subducting rocks 
Authors: Dobe Ritabrata , Giuntoli Francesco , Vitale Brovarone Alberto
Published: March 2024

Carbon recycling in subduction zones involves metamorphism and fluid-rock interactions that are responsible for dissolution or destabilization of carbon-bearing minerals. Such large-scale devolatilization of carbonates should impose profound alterations in the rheology of subducted lithologies, but this is an aspect that has received relatively scant attention so far.  

This work focuses on the mechanical behaviour of carbonates in subducted carbonated serpentinites that constitute a substantial fraction of carbon input into subduction zones. These investigations have been conducted on carbonated serpentinites from the Negru Shear Zone in Corsica (France). Petrographic and fluid inclusion analyses indicate that these rocks recorded partial carbonate reduction by infiltrating H2-rich fluids, as indicated by the conversion of carbonate to graphite and CH4​(Peng et al., 2021; Vitale Brovarone et al., 2017)​. The first generation of carbonate occurs as mm-sized equigranular, subhedral dolomite, with sutured grain boundaries (hereafter referred to as Carb1) along which graphite is distributed as discontinuous seams. Carb1 is fractured and brecciated, with limited evidence for crystal plasticity. A second generation of carbonate (calcite; Carb2), is observed in sheared carbonate + serpentinite domains, wherein the proportion of graphite is substantially higher. Carb2 grains are anhedral, elongate and form S-C structures within localized (~200 microns thick) shear zones.  

Electron Backscatter Diffraction (EBSD) analyses on the different carbonate domains provide greater insights into the deformation of Carb1&2. The microstructures within the dolomite-rich domains are dominated by twinning, with a strong crystallographic preferred orientation manifested by an M-index of 0.61. Dolomite grains display limited low angle boundaries and dislocations, which imply minimal strain accommodation by crystal plasticity and recrystallization during deformation. The occurrence of extensive twinning in dolomite coupled with antigorite being the dominant serpentine mineral, constrains the brecciation of dolomite grains to temperatures higher than 380 °C during the high-pressure evolution of Alpine Corsica. On the other hand, calcite grains within the shear zones have a weaker preferred orientation (M-index of 0.086), abundant low angle boundaries and dislocations, and lesser twin boundaries compared to the dolomite grains. Our observations are relevant for an improved understanding of the deformation of carbonated lithologies in faults associated with subduction zones. If these lithologies are dominated by dolomite, brecciation, likely associated with seismicity, may be the dominant mechanism of deformation, as crystal plastic mechanisms within dolomite are non-operative at the temperatures (
Participative gravity-modelling challenge to constrain the Balmuccia peridotite body (Ivrea-Verbano Zone, Italy)
Authors: Hetényi György , Baron Ludovic , Scarponi Matteo , Subedi Shiba , Michailos Konstantinos , Dal Fergus , Gerle Anna , Petri Benoît , Zwahlen Jodok , Langone Antonio , Greenwood Andrew , Ziberna Luca , Pistone Mattia , Zanetti Alberto , Müntener Othmar
Published: March 2024

The Balmuccia peridotite exposes relatively fresh mantle rocks at the Earth’s surface, and as such it is of interest for geologists and geophysicists. The outcrop is a kilometre-scale feature, yet its extent at depth is insufficiently imaged. Our aim is to provide new constraints on the shape of the density anomaly this body represents, through 3D gravity modelling. In an effort to avoid personal or methodology bias, we hereby launch an invitation and call for participative modelling. We openly provide all the necessary input data: pre-processed gravity data, geological map, in situ rock densities, and digital elevation model. The expected inversion results will be compared and jointly analysed with all participants. This approach should allow us to conclude on the shape of the Balmuccia peridotite body and the associated uncertainty. This crowd effort will contribute to the site surveys preparing a scientific borehole in the area in frame of project DIVE. The full description, the dataset, as well as the tentative timeline can be found at https://zenodo.org/records/10390437
Modelling the Impacts of Summer Extreme Precipitation Events on Surface Mass Balance in Southern Greenland
Authors: Loeb Nicole , Crawford Alex , Stroeve Julienne
Published: March 2024

The warming Arctic climate drives an increased potential for extreme precipitation events. Here, extreme precipitation is defined as the top 5% of daily accumulations where at least 1 mm occurred. Case studies have shown that these events can have substantial impacts on the regional surface mass balance (SMB) of the Greenland Ice Sheet. Depending on the precipitation phase and timing, mass may be added via the precipitation, or melt may be enhanced from rainfall, driving increased runoff and ice discharge. Southern Greenland is an area undergoing substantial change in terms of both intense precipitation occurrence and SMB, so it is essential to understand their relationship as the climate warms.Observations of extreme precipitation are limited due to its rare nature and sparse observational networks. Modelling studies can shed light on broader changes by filling in data gaps and providing future projections, allowing for a deeper look into physical linkages and changes. Here, historical and future simulations of the Regional Atmospheric Climate Model (RACMO) and Variable-Resolution Community Earth System Model (VR-CESM) are used. Representation of summer extreme precipitation events in southern Greenland in VR-CESM and RACMO is explored and compared through case studies. Key variables, including precipitation phase, runoff, and overall SMB are evaluated to discern potential impacts in each model. Events in the historical and future (following SSP5-8.5) periods are investigated to determine whether the response to events of similar magnitude and seasonal timing differs in a warmer climate.Furthermore, an approximation of how these extreme precipitation events influence seasonal SMB is presented by assessing the ratio of the event-related anomaly to the cumulative seasonal SMB anomalies. Comparisons of event-specific contributions with broader seasonal variations shed light on the connection between short-term meteorological events and longer-term climatic shifts in shaping Greenland's SMB.
Does model complexity of a pedotransfer function for soil hydraulic properties hamper its transferability?
Authors: Schoch Julian , Nussbaum Madlene , Walthert Lorenz , Carminati Andrea , Lehmann Peter
Published: March 2024

Land surface models need information on soil hydraulic properties (SHP) that are often estimated using pedotransfer functions (PTFs). Due to a lack of calibration data, PTFs must be applied that were trained for regions and land use types outside the region of interest. In this study, we quantify the transferability of PTFs to new regions as function of mathematical complexity and number of covariates. For that purpose, we trained new PTFs for forest soils based on a dataset of 25 soil profiles from climatically moderate regions of Switzerland. In a second step, we tested the new and some existing PTFs in a drier and hotter Swiss region (Valais). Tests of transferability showed that increasing the mathematical complexity (from a linear model to a highly non-linear random forest model) was always beneficial for the predictive power in new regions. Increasing the number of covariates revealed a trade-off between improving the accuracy of the predicted soil water retention curve and reducing accuracy of the soil hydraulic conductivity. Interestingly, the use of environmental predictors (climate data) hampers transferability the most due to large climatic contrasts between the calibration and validation regions. These results suggest that transferability works better for PTFs using fewer predictors. We recommend the use of non-linear PTFs based on soil texture, soil density, and organic carbon content for optimal prediction accuracy in regions without training data. This work highlights that the models with the highest number of predictors are not optimal for achieving transferability and that reducing the number of predictors can be beneficial.
An exploration of the geoheritage of the Soutpansberg range, South Africa
Authors: Kori Edmore
Published: March 2024

South Africa is a country endowed with great landscapes. The country’s strategic location at the southern tip of Africa juxtaposes it to be a melting pot of both biological and geomorphological diversity. Therefore, the country has some magnificent mountain ranges that have deep significance within the local communities. One such mountain is the Soutpansberg range in Limpopo Province. Positioned in the northernmost parts of the country, the Soutpansberg range stretches from east to west and forms a large portion of the Vhembe Biosphere Reserve. The range is an important landmark of the region. Consequently, it is a significant geoheritage feature. This paper explores the geomorphological features found in the mountain range and illustrate their significance to the local heritage. The geomorphological features range from hydrological features like waterfalls and potholes to geomorphological ones such as cliffs and gorges. All have a deep legacy in the region.
A Maxey-Riley modeling framework for Sargassum raft drift
Authors: Olascoaga M. Josefina
Published: March 2024

Sargassum has historically been found in the subtropical North Atlantic gyre where it provides important habitat for diverse marine species. However, since 2011 with the development of the Great Atlantic Sargassum Belt in the equatorial Atlantic, abundance has greatly increased, resulting in shorelines mass stranding. These coastal inundations of Sargassum have major impacts on the ecology, economies, and health of affected areas.Understanding the Sargassum raft's motion is required to be able to predict the areas that could be affected by Sargassum. The motion of the rafts is fundamentally unlike Lagrangian (i.e., infinitesimally small, neutrally buoyant) particle motion since they represent finite-size, buoyant objects subjected to the action of ocean currents, wind, and waves. In this talk, we will present a Maxey-Riley model for the motion of Sargassum rafts that takes their inertial nature into account as well as the elastic interactions within a raft and physiological changes affecting the structure of the rafts.  This will be accompanied by a discussion of results from field and laboratory experiments used to validate the model. Joint work with F. J. Beron-Vera and G. Bonner.
Testing the veracity of satellite-derived end-of-season snowline altitudes as a proxy for the glacier ELA.
Authors: Hallford Mhairi
Published: March 2024

Extensive databases of satellite imagery are now available and can be used to undertake assessments of the mass balance of glaciers. Previous studies have mapped the end-of-season snowlines (ESS) on glaciers from satellite imagery to find their snowline altitudes (SLA) and used these as proxies for the glacier equilibrium-line altitudes (ELA). This approach is advantageous because it can be implemented at scale and may employ automated methods. The veracity of using remotely measured SLAs as a proxy for in-situ measured ELAs however, has not yet been robustly demonstrated.This project is undertaking a systematic mapping of ESSs on glaciers with existing measured mass balance records to determine the errors associated with remotely measured SLAs. Glaciers are selected from the World Glacier Monitoring Service (WGMS) Fluctuations of Glacier (FoG) database. For each ELA record, we identify the Landsat image closest in date to the original ELA measurement (where cloud cover is minimal) and the image with the highest altitude snowline for the year. For each image, the snowline is mapped, and its corresponding SLA is extracted from the ASTER Global Digital Elevation Map (ASTERGDEM). The SLAs vs. ELAs of glaciers covering time series greater than 20 years are presented.
Unveiling the Spatio-Temporal Characteristics and Driving Mechanisms of Non-Grain Land Use Dynamics in Agricultural Socio-Ecosystems: A Case Study of the Sichuan Basin, China
Authors: Chen Shuocun , Xiao Wu , Xu Suchen , Niu Lu , Zhang Zhengfeng
Published: March 2024

Against the backdrop of the global heightened geopolitical tensions and climate change, the issue of food security is a major topic currently faced by countries around the globe. As the most populous country in the world, China's food security issues will impact the sustainability of global food production and supply stability. Despite the emphasis on food security and cultivated land protection, China is facing the latent threat to food production caused by the non-grain use of cultivated land, where land previously used for cultivating food crops is being extensively planted with cash crops or used for forestry development. Not only will this phenomenon increase the pressure on China's self-sufficiency in food, but it will also damage the stability of the agricultural ecosystem and weaken the sustainability of food production in the long term. As the main grain-producing area in Sichuan Province and even in western China, the Sichuan Basin has a solid agricultural foundation. In recent years, the phenomenon of non-grain use has become increasingly prominent, necessitating an exploration of its driving mechanisms and the implementation of governance measures. Set in the Sichuan Basin, this paper employed the sliding window method to continuously monitor and extract the non-grain patches between 1991-2018 in the study area based on the annual China Land Cover Dataset (CLCD). We used advanced data-driven approaches, including geographically weighted regression models and geographical detector models, to explore the direction and strength of the impact of driving factors on the non-grain phenomenon. Finally, using process tracing based on policy texts, non-grain evolution is interpreted. In conclusion, increased economic activity exacerbates non-grain use, and objective spatial positions constrain the impact of locational factors on non-grain use. Natural factors fundamentally and decisively explain the level of non-grain use. Decreased temperature and increased slope will intensify this phenomenon, and the impact of precipitation on non-grain exhibits a threshold effect. China's three agricultural structural adjustments have potentially influenced the overall trend of the non-grain phenomenon. The Wenchuan earthquake and subsequent reconstruction had a short-term impact, while the central and local government's attention to the issue of non-grain and a series of arable land protection measures are the main reasons for the sharp decrease in the non-grain phenomenon after 2015. Differentiated policy measures are recommended for mountainous and plain regions to address these socio-ecosystem changes, balancing the goals of food production and ecological protection. This approach will ensure grain production is more adaptable to climate change and aligned with the intensity of economic activities.
Application of mixed least-squares FEM to study sea ice dynamics
Authors: Hellebrand Sonja , Schwarz Carina , Schröder Jörg
Published: March 2024

The behavior of sea ice has been studied for many decades. In order to model its viscous-plastic behavior at scales spanning several thousand kilometers, different numerical models have been proposed. Based on the established approach in [1], this contribution presents a simulation model for sea ice dynamics to describe the sea ice circulation and its evolution over one seasonal cycle. In course of that, the sea ice concentration and the sea ice thickness are considered, of which the physical behavior is governed by transient advection equations. Here, the sea ice velocity serves as coupling field.Recently developed approaches base on a finite element implementation choosing a (mixed) Galerkin variational approach, see e.g. [2] and [3]. But therein, challenges may occur regarding the stability of the numerically complex scheme, especially when dealing with the first-order advection equations. Thus, we propose the application of the mixed least-squares finite element method, which has the advantage to be also applicable to first-order systems, i.e., it provides stable and robust formulations even for non-self-adjoint operators, such as the tracer equations (for sea ice thickness and sea ice concentration).For solving the instationary sea ice equation the presented least-squares finite element formulation takes into account the balance of momentum and a constitutive law for the viscous-plastic flow. The considered primary fields are the stresses σ, the velocity v, the concentration Aice and the thickness Hice. In relation, four residuals are defined for the derivation of a first-order least-squares formulation based on the balance of momentum, the constitutive relation for the stresses, and two tracer-equations. Different approaches can be made with respect to the approximation functions of the primary fields, i.e., choosing e.g. conforming (H(div) interpolation functions) or non-conforming (Lagrangian interpolation functions) stress approximations, while Lagrangian interpolation functions are chosen for the remaining fields. In order to compare such approaches, the box test case is utilized, cf. [3], which is well described in literature.References:[1] W.D. Hibler III. A dynamic thermodynamic sea ice model. Journal of Physical Oceanography, 9(4):815-846, 1979.[2] S. Danilov, Q. Wang, R. Timmermann, M. Iakovlev, D. Sidorenko, M. Kimmritz, T. Jung. Finite-Element Sea Ice Model (FESIM), Version 2. Geoscientific Model Development, 8:1747-1761, 2015.[3] C. Mehlmann and T. Richter. A modified global Newton solver for viscous-plastic sea ice models. Ocean Modelling, 116:96-107, 2017.
What are the alternative pumping strategies to stimulate areservoir without triggering distant faults?
Authors: Vallier Bérénice , Toussaint Renaud , Fahs Marwan , Baujard Clément , Genter Albert , Flekkøy Eirik Grude , Måløy Knut Jørgen
Published: March 2024

In the context of deep reservoir exploitation, it is necessary to enhance reservoir permeability before exploitation. One method to achieve this is by conducting stimulations through fluid injection, which increases pore pressure, reduces the effective normal stress and allows dilatant shear and porosity increase along small fractures in the reservoir, in the vicinity of the injection well. The pore pressure diffuses throughout the reservoir and can also sometimes reach distant faults that are critically stressed, with a risk to trigger seismicity along these. The model we propose aims to decrease the effective normal stress reduction caused by pressure disturbance along such distant faults, which can cause the rupture of critically stressed distant faults and induce seismic activity. This work investigates an alternative pumping method to stimulate a reservoir without triggering distant faults. To achieve this, a numerical model based on the finite difference method has been developed to solve the diffusion equation of pressure disturbances. The simplifying assumption is that the domain is isotropic and homogeneous. The 2D domain represents the fault plane and permeable damaged zone embedded in less permeable rock. To validate the numerical model, the numerical distant pressure disturbances are compared to analytical solutions developed from the Green's function of the diffusion equation. The numerical model investigates the impact of a time-dependent oscillating injection strategy on near-well and distant pressure disturbances, in comparison to other tested methods, to minimize induced seismicity. The results suggest that the oscillating pumping strategy has the potential to significantly reduce induced seismicity on distant faults. Future research will involve developing mitigation strategies using more complex models that incorporate realistic fault geometries and operational conditions.