bluuebunny/crossref_metadata_2025 huggingface dataset:
Kelvin–Helmholtz Waves within the Rising Turbulent Layer during the Morning Transition at Dome C, Antarctica: Regimes and Patterns
Authors: Petenko Igor , Casasanta Giampietro , Kallistratova Margarita , Lyulyukin Vasily , Genthon Christophe , Sozzi Roberto , Conidi Alessandro , Cecilia Andrea , Argentini Stefania
Published: March 2024

Understanding processes of wave-turbulence interactions in stably stratified shear flows is a challenging problem in atmospheric physics and hydrography. This observational study emphasizes the importance of carefully considering Kelvin–Helmholtz (KH) waves and their interaction with vortical turbulence for an adequate description and parametrization of the stable boundary layer.
This study investigates two phenomena, traditionally discussed separately, occurring during the morning transition from stable to unstable stratification at Dome C, Antarctica. Using high-resolution sodar echograms, the simultaneous occurrence of (i) the morning rise of the inversion turbulent layer, and (ii) KH waves within this layer was observed. Regular braid-like structures associated with KH shear instabilities within the elevated turbulent layer were observed in more than 70% of days over a four-month summer period.
Two regimes of the morning evolution (when KH waves occurred) are identified, depending on the presence or absence of turbulence during the preceding night. The weather and turbulent conditions favoring the occurrence of these regimes are analyzed corresponding the morphology of the wind and temperature fields retrieved from an instrumented 45-m tower with six measurement levels.
Two distinct patterns of KH waves are observed: (1) quasi-periodical (with periods ≈ 8−15 min) trains containing 5−10 braids, (2) about continuous series lasting 20–70 min containing 20−80 braids. A composite shape of KH waves is determined. The periodicity of these waves is estimated to be between 20 and 70 s, and their wavelength is estimated roughly to be 100−400 m. The vertical thickness of individual braids at the wave crests ranges between 5 and 25 m. The total depth of a rising turbulent layer containing these waves varies between 15 and 120 m, and the ratio of the wavelength to the depth of the wave layer varies from 3 to 12 with a mean value ≈ 8.
Numerical simulations face challenges in reproducing turbulent wavelike structures, particularly KHBs. Further investigation is needed to unveil the precise mechanisms driving the morning elevation and growth of KH waves along with the developing convective layer.
Quantification and partitioning the contributions of abiotic and biotic processes to soil N-oxides emissions in the Dead Sea valley, Israel.
Authors: Yagle Isaac , Gelfand Ilya
Published: March 2024

Wetting of dry soil after prolonged drought triggers emissions of N-oxides (nitric oxide; NO and nitrous oxide; N2O) and this post-wetting burst may contribute disproportionately to annual soil N-oxides emissions in drylands. During the wetting, nitrification and denitrification were shown to be the major sources of soil N-oxides emissions. Several abiotic reactions involving the nitrification intermediates- e.g. nitrite (NO2-), however, may also contribute to the production of N-oxides in soils. The contribution of these abiotic reaction to N-oxides emissions, despite potential importance is not well quantified. To quantify and partition the contribution of abiotic and biotic processes to post-wetting N-oxides emissions in drylands, we measured soil NO and N2O production in a laboratory incubation with live and gamma-irradiated soils. Samples were collected under canopies of dominant local (Acacia tortilis) and invasive (Prosopis juliflora) trees, as well as from bare soils outside the canopy cover.We found that that while the overall dynamics of soil NO and N2O emissions were similar in gamma irradiated and live soils under both P. juliflora and A. tortilis trees, as well as in bare soils, the magnitudes and rates of emissions exhibited significant disparities. In particular, gamma irradiated soils under A. tortilis canopies after eight hours’ incubation, emitted ~10 times less NO (~5 ng N g-1) and ~4 times less N2O (~10 µg N g-1) compared to the live soils. While gamma irradiated soils under P. juliflora canopies emitted ~2 times less NO (~7 ng N g-1) and similar N2O (~7 µg N g-1) compared to the live soils, and in the bare soils, ~9 times less NO (~5 ng N g-1) and similar N2O (~10 µg N g-1). Our findings suggest that both biotic and abiotic pathways contribute to N-oxides production following dry soil wetting, however, the relative contribution is dependent on the landscape position and affected by plant presence and species. Specifically, abiotic processes contributed 10% to soil NO and 25% to N2O production in soils beneath A. tortilis canopies and between 10% and 75% in the bare soils. In soil under P. juliflora canopies abiotic processes contributed five times more to the NO production (50%) while N2O production was solely from abiotic activity.
What happens when an inertially unstable jet approaches a lateral boundary?
Authors: Ferreira Azevedo Matheus , Poulin Francis , Lamb Kevin
Published: March 2024

Much of our understanding of inertial instability in geophysical flows comes from atmospheric physics, and these studies have neglected the impact of lateral boundaries. To address this shortcoming, we performed a series of high-resolution 3D numerical simulations in Oceananigans in the context of the nonhydrostatic Boussinesq equations assuming a rigid-lid approximation. An inertially unstable baroclinic jet was investigated both far away and adjacent to a vertical boundary. The jet was chosen to be in thermal-wind balance and the buoyancy field was perturbed to instigate the instability.We found that when the unstable jet is sufficiently close to the vertical boundary, the wavenumber of the fastest-growing unstable mode nearly doubled when compared to the jet far away from the boundary. We have not observed this shift to smaller scales in the context of a barotropic jet. The growth rates of the instability, measured by taking the l2 norm of the velocity components, showed an initial linear growth phase in the first few days with no significant differences regarding the positioning of the jet. After this period, non-linear saturation stabilized the jet to inertial instability, and a secondary baroclinic instability developed. These findings suggest a previously unaccounted factor that can influence the bio-physicochemical properties of the ocean in proximity to coastal boundaries, contributing to the current understanding of the importance of submesoscale phenomena.
Kinetic properties of proton and alpha beams in the Alfvénic wind observed by Solar Orbiter-PAS 
Authors: De Marco Rossana , Bruno Roberto , D'Amicis Raffaella , Perrone Denise , Marcucci Maria Federica , Telloni Daniele , Marino Raffaele , Sorriso-Valvo Luca , Fortunato Vito , Mele Gennaro , Monti Francesco , Fedorov Andrei , Louarn Philippe , Owen Christopher J. , Livi Stefano
Published: March 2024

Ion velocity distribution functions in solar wind are often found to be non-Maxwellian. Streams of accelerated particles and temperature anisotropies are typical non-thermal features, whose origin is debated since the early years of in situ measurements. In order to disentangle the kinetic processes which may play a role in the generation of such distortions, particle double streams need to be identified and isolated. To this purpose, we have developed a numerical approach that leverages the clustering technique employed in machine learning. Here, we present the results obtained applying our technique to the ion distribution functions of a typical fast Alfvénic wind stream observed by Solar Orbiter-PAS in mid-September 2022, at a heliocentric distance of about 0.58 au. We could separate up to four ion families, namely proton core and beam and alpha core and beam. This allows us to characterize and compare their features, like the relative densities and temperatures. Differently from the better-known proton beam, alpha beam represents a relevant fraction of the alpha population, around 40%. Separating such a massive beam may shed new light on alpha kinetic features like the anomalous overheating mechanism. Moreover, the study of the velocity drift of the various ion populations indicates that both the alpha core and the alpha beam are sensitive to the Alfvénic fluctuations, and the surfing effect found in literature can be recovered only when considering the core and the beam as a single population.The similarities between proton and alpha beams would suggest a common generation mechanism, apparently due to local physical conditions in the plasma.  
Comparison of noise levels of different magnetometer types and space environments
Authors: Timmermann Gerlinde , Pöppelwerth Adrian , Richter Ingo , Auster Hans-Ulrich , Plaschke Ferdinand
Published: March 2024

The plasma environment around Earth is divided into several distinct regions with vastly different characteristics of the magnetic field. For example, inside the magnetosphere the magnetic field can reach tens of thousands of nanotesla. In the magnetosheath between Earth’s magnetosphere and the bow shock, the magnetic field is lower, but significantly more turbulent. In the solar wind outside Earth’s magnetic influence, magnetic fields are low and less fluctuating. Magnetic fields in space have typically been measured with fluxgate magnetometers on spacecraft. In recent years, various magnetometer types have been discussed and/or flown, i.e. optically pumped magnetometers or anisotropic magnetoresistive magnetometers. We discuss and compare noise level performances of diverse magnetometer types and contrast them with the requirements needed to accurately observe the magnetic field and distinct plasma phenomena therein in particular regions of space for scientific research.
The EarthCARE ATLID profile processors
Authors: Donovan David , van Zadelhoff Gerd-Jan , Wang Ping
Published: March 2024

ATLID (Atmospheric Lidar) is the lidar to be embarked on the Earth Clouds and Radiation Explorer (EarthCARE) mission. EarthCARE is a joint ESA-JAXA mission and will embark a cloud/aerosol lidar (ATLID), a cloud-profiling Radar (CPR) a multispectral cloud/aerosol imager (MSI) and a three—view broad-band radiometer (BBR). ATLID is a 355nm high-spectral-resolution, polarization sensitive lidar.The accurate retrieval of aerosol and cloud properties from space-based lidar is a challenging endeavor, even when the extra information provided by an HSRL system is exploited. The generally low signal-to-noise (SNR) ratios involved coupled with the need to respect the structure of the aerosol and cloud fields being sensed are particular challenges.Over the past several years, cloud/aerosol algorithms have been developed for ATLID that have focused on the challenge of making accurate retrievals of cloud and aerosol extinction and backscatter specifically addressing the low SNR nature of the lidar signals and the need for intelligent binning/averaging of the data. Two of these ATLID processors are A-FM (ATLID featuremask) and A-PRO (ATLID profile processor). A-FM uses techniques adapated from the field of image processing to detect the presence of targets at high resolution while A-PRO (using A-FM as input) preforms a multi-scale optimal-estimation technique in order to retrieve both aerosol and cloud extinction and backscatter profiles.Adaptations of the A-FM and A-PRO processors have been developed for Aeolus (called AEL-FM and AEL-PRO, respectively) and have been introduced into the Aeolus L2a operational processor. In this presentation A-FM and A-PRO will be described. Results based on simulated data for A-FM and A-PRO and results using AEL-FM and AEL-PRO using Aeolus observations will be presented and discussed. 
Saturated hydraulic conductivity spatialization strategy to model recharge and hydrogeological transfers on an industrial site in France
Authors: Andriatahiana Salohy Nantenaina , Sinabarigui Idrissou , Courtois Nathalie , Vandervaere Jean-Pierre , Cohard Jean-Martial
Published: March 2024

Pollutant transfers in the critical zone is an issue for decades both because of complex physico-chemical interactions in the porous media and because of the emergence of new materials/molecules rejected in the environment for which rules are not ready. The study presented here is part of a research project which aimed to predict transfers and residence time of pollutants in the critical zone including the Unsaturated Zone (UZ), and in aquifers on the CEA Cadarache site (France). This site benefits from a large instrumentation for decades to survey both the water dynamic and quality in the aquifers below the industrial facilities. One of the remaining challenges is to study the distributed recharge in the UZ. In situ measurements of saturated hydraulic conductivity Ks are often time-consuming, but also costly to implement at a catchment scale. To overcome this difficulty, an approach using Pedotransfer Functions (PTFs) is possible in order to spatialize this parameter of the UZ (Nasta et al., 2021; Weihermüller et al., 2021). The main objective of the study is to evaluate a spatialization strategy of Ks values using PTFs calibrated from an intensive in situ measurement campaign.A total of 48 measurement points were selected on the study site, covering an area of around 900 hectares. The points were chosen to represent the different types of geological formations at the outcrop as well as the different types of land cover on the site. For all those locations, in situ hydraulic conductivity measurements were carried out with a disc infiltrometer, using the multi-potential method (Vandervaere, 1995), together with physico-chemical analyses of the surface soils. The results obtained show that for most of the measurement points, a fairly clear break in the slope of the exponential function K(h) appears for potentials h around -30 / -20 mm. The estimate of the value of Ks is chosen as being the value of K(h) obtained for the last value of potential h = - 5 mm, considering that saturation has been reached. On site, Ks varies from 20 to 410 mm/h.Several PTFs for estimating Ks were selected (Rawls & Brakensiek, 1985, Wösten et al., 1999, Weynants et al., 2009, Szabó et al., 2021, Rosetta (Schaap et al., 2001; Zhang & Schaap, 2017)). The study will help us to identify some geological or land cover drivers for Ks ranges and to select which PTFs are able to represent such a variability.
Climatic conditions impact As and Cd mobility differently in flooded paddy soils
Authors: Wang Tianyu , Planer-Friedrich Britta , Kümmel Steffen , Muehe E. Marie
Published: March 2024

Arsenic (As) and cadmium (Cd) contamination in rice paddy soil are prevailing due to human activities including the application of agrochemicals and wastewater irrigation. Due to their inherently different geochemistry, As transitions to the porewater becoming more mobile under flooded water management while Cd binds to sulfidic minerals becoming more immobile. We currently have little understanding to which extent future climatic conditions imprint on native and elevated Cd and As mobilities in paddies, and whether they influence each other when being present in elevated concentrations together.In order to close this gap in knowledge, we performed an incubation experiment with flooded paddy soils exposed to two different climatic conditions. The soil either contained the native metal(loid) content or elevated As and Cd realistic for contamination scenarios (+15 mg/kg As, +0.7 mg/kg Cd, or combined with +15 mg/kg As and +0.7 mg/kg Cd). Future climatic conditions were set relative to today’s climatic conditions (ambient CO2 and room temperature) with 850 ppm atmospheric CO2 and +4°C air temperature.Adsorbed As approximated with 0.01 M CaCl2 extraction and outer-mineral associated As approximated with 0.1 M HCl extraction increased under flooded soil conditions over the incubation period, whereas 0.01 M CaCl2-extractable Cd decreased and 0.1 M HCl-extractable Cd remained stable, supporting prior knowledge on the contrasting geochemical behaviour of these two contaminants under flooded conditions. Future climatic conditions enhanced the increase of CaCl2 –extractable As but not 0.1 M HCl-extractable As when present as a single contaminant, indicating that climatic conditions influenced As dynamics on the surface of minerals but were not able to exert deeper into mineral phases. CaCl2- and HCl-extractable Cd were not affected by climatic conditions when present as a single contaminant, indicating resilience to climatic change. In the presence of combined As and Cd, the enhancement of the increase of CaCl2-extractable As by future climatic conditions was eliminated suggesting a toxicity of Cd to As-cycling related microbes which offset the stimulation by future climatic conditions.Respirational output and other microbial dynamics data will be discussed relative to climatic impacts on either of these two contaminants and their combination.Our findings show a link between climatic conditions and metal(loid) contaminant mobility under flooding conditions. The results of combined elevated As and Cd indicate a more realistic situation which is potentially overlooked in previous studies.
Quaternary denudation rates in the Tianshan
Authors: Lavé Jérôme , Charreau Julien , Blard Pierre-Henri , Large Etienne , Zimmermann Catherine , Dominguez Stéphane , Sheng Li Wang
Published: March 2024

The Earth surface, where life develops and stands, is strongly affected by denudation which is the sum of physical erosion and chemical weathering. Denudation impacts soil formation and agriculture, affects the relief stability and, at the geological time scale, controls the atmospheric CO2 via the weathering of silicates and the production of sediments that later bury organic matter in the oceans. In the context of global warming, it is particularly important to predict how denudation will change and hence impact the Earth Surface where we live. This requires to understand the links between past climate variability and denudation changes, especially during the Quaternary when Earth experienced rapid climate oscillations of amplitude similar to what is expected in the future due to anthropic impact. To reach this goal, quantitative estimate of past denudation rates during the Quaternary are needed.In this study, we reconstruct Quaternary paleo-denudation rates in the Tianshan range located in Central Asia because (1) it is a major orographic barrier that likely played an important role during the onset of Quaternary glaciations, (2) regional climate variations have been well documented by the geochemical and isotopic analyses of speleothems in caves and (3) well dated Quaternary deposits are abundant in the piedmontsTo reconstruct basin average paleo-denudation rates we used the inherited 10Be concentrations derived from the inversion of 10Be cosmogenic depth profile collected across abandoned alluvial surfaces. We used a unique inversion technique to reprocess preexisting data and also analyze 5 new cosmogenic depth profiles located in the northern Tianshan. In this region, to extend the dataset we have also collected 9 ancient river sand samples along the magnetostratigraphically dated Jingou He section. For comparison between all data, paleo-denudation rates are normalized to modern 10Be derived denudation rates across the same drainage basin. This yields to a 0-1.5Ma record of paleo-denudation rates that is compared to climate variations to discuss the potential links between the two.
Combining radar and optical satellite data to gather a comprehensive regional-scale dataset of the activity of slow-moving landslides in diverse tropical landscapes
Authors: Dille Antoine , Smets Benoît , Vanmaercke Matthias , Dewitte Olivier
Published: March 2024

Slow-moving landslides (SML; mm year−1 to 100 m year−1) can be a ubiquitous geomorphic process in tropical mountain landscapes. Yet, answer to crucial questions such as what landscape characteristics exert the most important control on their spatial distribution (e.g., slope, connection to rivers, climate, lithology, tectonic setting, recent deforestation, degree of anthropogenic activity, etc.), or how does their dynamic behaviour responds to landscape changes (urbanisation, deforestation, etc.), remains elusive – and is typically relying on information collected on single or a few landslide(s). Intrinsically complex, obtaining large-scale datasets with dense surface displacement measurements is even more so in the tropics, where field access is typically difficult, and rapid vegetation changes and persistent cloud cover hamper the use of satellite remote sensing. In this work, we attempt to overcome these limitations by exploiting synergies between spaceborne sensors (i.e., radar and optical) and deformation measurement techniques (i.e., interferometry and sub-pixel image correlation), to obtain multi-year datasets of the activity of SML in the western branch of the East African Rift (wEAR). Characterised by a large natural landscape and climatic diversity, the wEAR is exemplative of many tropical mountain regions, i.e., i) affected by large-scale land use changes and ii) disproportionately high landslide impacts and iii) largely overlooked in landslide research.  We collected a spatio-temporal inventory containing characterised by varying level of activity and behaviours, and located in contrasting environments. This regional-scale dataset will form the foundation for untangling the intricate influences of climate, lithology, tectonics and man-made environmental changes on the occurrence and activity of SML. By investigating their interaction with river system, we also aim at estimating how they contribute to controls on river sediment budgets, regional erosion rates, channel network evolution and flooding patterns – key for our understanding of landscape evolution, sediment budgets and geo-hydrological hazards. Overall, this work aims at moving forward our understanding of a key geomorphic process in severely under-researched types of environments subject to rapid changes. This is not only essential for a better hazard assessment, but also for comprehending how (human-induced and/or natural) environmental changes affect these landscapes and the sediment dynamics.
Evolution in space and time of a regional-scale fault: example from the Orobic Thrust (European Alps, Southalpine Domain)
Authors: Zanchetta Stefano , Rocca Martina , Montemagni Chiara , Viola Giulio , Aldega Luca , Zanchi Andrea
Published: March 2024

Despite the small volume they occupy in the crust, fault zones are of striking importance as they localize both seismic slip and aseismic deformation, as well as fluid migration at middle to shallow crustal levels. Regional-scale fault systems may benefit of long-lived activity as, due to their rheological weakness, they can be also reactivated by weak far-field stresses in a variety of tectonic settings. The architecture of fault zones that experienced multiple re-activation is complex and accurate structural analyses, including also the identification of (micro)structural facies (Brittle Structural Facies, BSF) and their crosscutting relationships, is mandatory to solve the spatial evolution and relative chronology of the fault zone.The Orobic Thrust is a regional-scale fault zone, more than 80 km in length, representing one of the largest structures in the European Alps retro-belt. Along the thrust plane the Variscan basement is thrusted southward over the Upper Carboniferous to Lower Triassic volcano-sedimentary cover of the Southalpine Domain. In several areas the fault zone, ca. 250-300 m thick, is continuously exposed, allowing the detailed reconstruction of the fault architecture. A narrow (20-25 m) protomylonitic band marks the top of fault zone suggesting temperature of at least 300°C in the early stage of fault activity. Temperature in excess of 200°C are also supported by analysis of the thermal maturity of clay mineral assemblages (
Observing links between lifetimes of satellite detectable contrails and aircraft type
Authors: Gryspeerdt Edward , Stettler Marc , Teoh Roger , Burkhardt Ulrike , Delovski Toni , Painemal David
Published: March 2024

Clouds produced by aircraft (contrails) are responsible for over half of the positive radiative forcing from aviation, leading to the proposal of contrail avoidance as a method for mitigating the climate impact of aviation. This requires accurate prediction of the radiative properties of individual contrails, which themselves are highly dependent on the contrail microphysical properties, lifetime and macrophysical evolution along with the background atmospheric state.  In-situ observations have also shown an impact of the generating aircraft and its fuel type on the properties and evolution of contrails. However, these observations are typically made close to the aircraft, with fewer observational constraints for the properties of the longer-lived contrails that drive the majority of the radiative forcing.Coupling satellite observations of contrails with flight data, we track contrails formed by individual aircraft over the North Atlantic. We find a strong link between aircraft type and contrail lifetime, with newer, more fuel-efficient aircraft forming longer-lived contrails. This relationship is not driven by the aircraft properties, but rather by operational differences in aircraft flight patterns, with the newer types flying higher in this region and so producing contrails with longer lifetimes. We present some encouraging initial evidence of reductions in aircraft soot emissions affecting contrail lifetime.
Signatures of a regime of episodic localized subduction: from laboratory experiments to Venus
Authors: Davaille Anne
Published: March 2024

The dynamic regime prevailing in the mantle of present-day Venus is still unknown. The surface of Venus seems uniformly quite young; it has  been proposed that it was due to a catastrophic resurfacing 150-700 Ma, and that the planet was in a stagnant lid regime since. Indeed, Magellan observations have failed to reveal a continuous set of accretion ridges and subduction zones, signatures of plate tectonics. But subduction features (trench, elastic bulge) are present in a number of localized spots, for exemple around two of the largest coronae, Artemis and Quetzelpetlal. There, subduction would be mainly by roll-back and could have been induced by the impingement of a mantle plume under the lithosphere, as predicted by our recent fluid dynamics laboratory experiments. Further analysis of our experiments suggest that subduction would be facilitated by the presence of a few % of a liquid phase in the asthenosphere. Melt would be most likely for the Venusian case, as anyway hinted by the amount of volcanic features on the surface of the planet. The experimental scaling laws further suggest that roll-back and subduction could be quite fast (10 cm/yr) because of the old age of the subducting lithosphere and the transformation to eclogite of the basaltic crust. This is turn would generate the rapid opening of a back-arc basin. Laboratory experiments show that for Venus temperature conditions, the produced crust and lithosphere could be quite disorganized with a contorted spreading center, large transforms and microplates. Moreover, the buoyancy of the newly created plate would cause it to remain quite elevated compared to the surrounding plains. Hence, inspection of the topography of Venus suggests several new plates created by subduction: beside the interior of Artemis coronae, Enyo Fossae and Asthik Planum could be plausible candidates. 
A 21 km SMART Cable for earthquakes and tsunami detection operating in the Ionian Sea
Authors: Marinaro Giuditta , D'Amico Salvatore , Embriaco Davide , Giuntini Alessandra , Simeone Francesco , O'Neill John , Nicholson Bruce , Watkiss Neil , Restelli Federica
Published: March 2024

Continuous seismic and environmental monitoring at remote seabed sites always faced a major challenge due to technical, logistical and financial effort. Commercial Telecommunication submarine cables continuously expand the coverage of ocean seafloor following society's needs to increase connectivity between distant countries and remote sites. Cables over thousands of kilometres long are equipped with in-line repeaters which compensate for optical losses due to  such long distances. A Science Monitoring And Reliable Telecommunications (SMART) Subsea Cables, designed by a Joint Task Force (JTF) across the International Telecommunication Union, World Meteorological Organization, the UNESCO Intergovernmental Oceanographic Commission,  may host, inside repeaters, scientific sensors for seismic, ocean and climate monitoring and disaster risk reduction in cases of tsunamis. The recent successful deployment at the Western Ionian Sea, one of EMSO (European Multidisciplinary Seafloor and water column Observatory) Regional Facilities, of the InSEA Wet Demo SMART Cable displays a world first demonstrating the feasibility of such installation using standard cable-laying techniques to show proof of concept. Commercial viability for these systems relies on the cable being laid as if the scientific element did not exist, thereby minimising additional deployment costs and reducing barriers to cooperation with cable laying companies. Güralp Systems Ltd and INGV deployed three seismometer-accelerometer pairs housed in inline repeaters along the 21km cable long. Each repeater also provides temperature and pressure devices which respectivley enable the real time monitoring of sea environment state and of sea surface level for tsunami detection.This pioneering installation demonstrates the feasibility of smart cable initiative which may lead to global coverage of ocean seafloor with a network of scientific sensors enabling the  real time monitoring of seismicity and tsunami events at remote locations thanks to a collaboration between scientific and commercial parties.
Atmospheric drivers of the rapid decline of Novaya Zemlya's glaciers
Authors: Haacker Jan , Wouters Bert , Fettweis Xavier , Box Jason , Glissenaar Isolde
Published: March 2024

The glaciers on the High Russian Arctic archipielago Novaya Zemlya have been losing roughly 10 Gt/yr over the past decade, 5 Gt/yr more than in the one before. While earlier research pointed to ocean discharge as driver of the acceleration, we present new results that show that foehn events, triggered by atmospheric rivers, led to the most severe melt events in the recent times. We use output of the regional atmospheric model MAR, together with geodetic observations from CryoSat-2, and reanalysis data (CARRA, ERA5, MERRA-2) to show that roughly 70 % of the melt occurs during atmospheric rivers episodes. Between 1990 and 2022, 45 of the 54 days with more than 1 Gt melt were accompanied by foehn winds. We conclude that the representation of atmospheric rivers and foehn winds in models is crucial for accurate projections of the future glacier evolution.
Predicting trajectories of temperate forest understorey vegetation responses to global change
Authors: Wen Bingbin ,   forestREplot and PASTFORWARD
Published: March 2024

Predicting forest understorey community responses to global change and forest management is vital given the importance of the understorey for biodiversity conservation and forest functioning. Though substantial effort has gone into disentangling how global change will impact the understorey community, the scarcity of information on site-specific environmental drivers together with large temporal and spatial drivers has limited our understanding of how global change drivers affect understorey characteristics at specific forest sites. Here, using understorey resurvey data collected from 1363 plots across temperate Europe and applying a machine learning approach, we used Gradient Boosting Regression Models (GBM) to model and predict trajectories of four understorey characteristics (species richness, total understorey vegetation cover, proportion of woody species and proportion of forest specialists) to global-change and site-specific drivers (e.g. soil, overstory conditions). We applied the final GBM models to 8 forest sites in Austria to evaluate the effect of future scenarios for nitrogen deposition, climate change and forest management on the forest understory in the year 2030, and project the trajectory of understorey properties from year 1993 to 2030.  The trajectory results showed that increasing nitrogen deposition decreased species richness and proportion of woody species, but increased total understorey vegetation cover and proportion of forest specialists. The effect of climate warming on the proportion of forest specialists appeared to be limited but led to a decrease in species richness, total vegetation cover and proportion of woody species. Finally, a closed canopy could shift the community towards more woody species and forest specialists but may lower species richness and total vegetation cover. Our presented model allows the prediction of trajectories of understorey vegetation responses to global change and management interventions at specific forest sites. 
Cal/Val of HR SWOT products using in-situ networks and in-flight nadir altimetry missions
Authors: Vayre Maxime , Renou Julien , Fjortoft Roger , Picot Nicolas
Published: March 2024

The Surface Water and Ocean Topography (SWOT) mission, conducted by CNES and NASA was successfully launched on 16 December 2022. It aims at providing unprecedented 2D observations of the sea-surface height and mesoscale structures as well as water surface elevation, water stocks estimates and discharge over hydrological areas. A SAR-interferometry wide-swath altimeter, namely the Ka-band Radar Interferometer (KaRIn), is designed to cover two 50-km cross-track swaths. During its Calibration (Cal/Val) phase (January to July 2023), SWOT mission provided daily measurements for each swath due to its 1-day repeat cycle. While the spatial coverage during this phase is not as large as for the nominal phase with a 21-day repeat cycle, such short revisit time is relevant for Cal/Val purposes.   The High Rate (HR) mode of KaRIn, dedicated to hydrology surfaces, provides HR SWOT products that are calibrated during the Cal/Val phase. The performance assessment of these SWOT observations can be achieved through the comparison against reference measurements. Although specific in-situ Cal/Val sites have been purposely designed for the validation of HR SWOT products on lakes and rivers, additional in-situ networks can also be useful, particularly if their spatial coverage allows a monitoring of lakes and rivers also observed by the SWOT mission. Such conditions are met for the French network (SCHAPI), providing several hundreds of georeferenced in-situ stations over rivers, and for the Swiss network (BAFU) which measures water surface elevation of main rivers and lakes. Moreover, the combination of measurements from current nadir altimetry missions (e.g. Sentinel-3, Sentinel-6 or ICESat-2) has also the potential to generate reference measurements on a large number of lakes and rivers.  Our analysis will essentially propose a preliminary performance assessment of the distinct high-level HR SWOT products during the Cal/Val phase, using existing in-situ networks and measurements from Sentinel-3, Sentinel-6 and ICESat-2. We will first take advantage of hydrological areas being densely monitored below SWOT swaths, which are relevant to assess the quality and current limitations of the products.
Triggered and recurrent slow slip in North Sulawesi, Indonesia
Authors: Nijholt Nicolai , Simons Wim , Broerse Taco , Riva Riccardo
Published: March 2024

Nearby faults interact with each other through the exchange of stress. However, the extent of fault interaction is poorly understood. In particular, closely tied tectonic systems like crustal-scale faults that are right next to subduction zone interfaces are likely to express such interactions. Interactions may lead to slow-slip activity, resulting in episodes of transient surface motion.Our study concentrates on Northwest Sulawesi (Indonesia), which hosts two fault zones with potential for major earthquakes and tsunamis: the strike-slip Palu-Koro fault and the Minahassa subduction zone. Both fault zones accommodate 4 cm/yr of interseismic relative motion. Thanks to a 20-year-long effort in geodetic monitoring, we are able to identify multiple periods during which surface velocities deviate from their interseismic trend. The most recent episode followed the 2018 Mw7.5 Palu earthquake.We use a Bayesian methodology with forward predictions of slip on the two fault interfaces to match the observations following the 2018 Mw7.5 Palu earthquake, and infer that both deep afterslip on the Palu-Koro fault and slow slip on the Minahassa subduction interface have caused the observed transient surface motion. This finding represents the first recording of a slow slip event on the Minahassa subduction interface. We also speculate that the subduction interface and the strike-slip fault are likely interacting on a regular basis, affecting the seismogenic potential of both parts of this tectonic system.
How drought can affect river network dynamics in a central Germany lowland river catchment
Authors: Li Yao , Jomaa Seifeddine , Lischeid Gunnar , Rode Michael
Published: March 2024

River network is usually not a static item. More than half of global river exhibit an intermittent pattern, ceasing to flow during drought and rewetting again as the environment getting wetter seasonally. Recently, climate change has led to intensified droughts in central and southern Europe, causing even perennial streams to transition to intermittent flow patterns. Understanding and estimating to what extent drought can affect river network expansion and contraction is important and remains challenging.This study aims to link river network dynamics and subsurface flow and to identify the potential influence of prolonged drought periods on the groundwater-river connection, and concomitant river network dynamics changes. To this end, we have coupled a fully-distributed hydrological model (mHM) with a groundwater model (Modflow) to investigate how prolonged droughts affect river network dynamics at the meso-catchment scale. The model was implemented in the Bode catchment, spanning 3200 km² in central Germany, from 2000 to 2022, in which the period 2018-2022 is considered as drought. We calibrated the model using discharge and groundwater table depth data from 2004 to 2008. Subsequently, we validated it using observations of discharge, groundwater table depth, and river dryness and wetness from 2009 to 2022.The results demonstrate that the model could reproduce the dryness and wetness of river networks. For the groundwater-river exchange, the length of streams with net water loss increased by 6% in the period 2018-2022 compared to 2004-2017. For the river network dynamics, temporally, total river network length shows an apparent decline. The mean and minimum river network length during recent drought years (2018-2022) decreased by 10.4% and 10.9% compared to 2004-2017, respectively. While the maximum river network of each year was reduced only by 4.37%.  Spatially, the decline of river network length mainly occurs in first and second order streams (60.2% and 25.8%). Further analysis of stream persistence shows that approximately 3% of stream reaches shift from perennial to intermittent pattern and around 8% of stream reaches transfer from intermittent pattern to permanently dry due to the drought from 2018 to 2022. This is likely not only to harm aquatic biota but to have a major impact on stream biochemistry as well.
A New Perspective on Agricultural Drought Periods: A Mediterranean Semi-Arid Context
Authors: Oukaddour Kaoutar , Le Page Michel , Fakir Younes
Published: March 2024

Extreme weather events have an increasing repercussions on ecosystems in recent years. By comprehending how vegetation responds to climatic extremes, their effects may be mitigated. In a semi-arid Mediterranean region, this study examines the temporal connections of the main triggers of agricultural drought, low precipitation, vegetation growth, thermal stress, and soil water deficit. Drought periods and their characteristics were determined using a revised run theory approach. The Pearson correlations across various spatial scales revealed a moderate to low degree of concordance among the drought indices. This discrepancy can be attributed to the geographical heterogeneity and climatic variations observed among the agrosystems within the basin.The cross-correlation analysis demonstrated the cascading impacts resulting from reduced precipitation. During drought events, the significant connection between precipitation deficits and vegetation persists for at least one month across most index pairs. This suggests that agricultural drought occurrences can be temporally linked through the selected drought indices. The study unveiled short-, mid-, and long-term effects of precipitation deficiencies on soil moisture, vegetation, and temperature. As anticipated, variables like soil moisture and surface temperature, being more instantaneous, exhibited no lag in response to precipitation. Notably, vegetation anomalies at the monthly time step displayed a two-month lag, indicating a preceding impact of vegetation on precipitation.Employing the run theory to identify drought events and stages with different thresholds revealed substantial variability in drought characteristics namely the duration, the magnitude magnitude, and the intensity. This variability was notably influenced by the selection of both normality and drought thresholds.
Surface oxygen concentration on the Qinghai-Tibet Plateau (2017–2022)
Authors: Hu Xiaokang , Chen Yanqiang , Huo Wenyixin , Jia Wei , Ma Heng , Ma Weidong , Jiang Lu , Zhang Gangfeng , Ma Yonggui , Tang Haiping , Shi Peijun
Published: March 2024

For the ecologically vulnerable Qinghai-Tibet Plateau (QTP), hypoxia is increasingly becoming an extremely important environmental risk factor that significantly affects the health of both humans and livestock in the plateau region, as well as hindering high-quality development. To focus on the problem of hypoxia, it is especially urgent to study the surface oxygen concentration (i.e., oxygen concentration). However, the existing research is not sufficient, and there is a lack of oxygen concentration data collected on the QTP. In this study, through the Second Tibetan Plateau Scientific Expedition and Research and field measurements, the oxygen concentration data and corresponding geographic environmental data were collected at 807 measurement points on the QTP from 2017 to 2022, and the spatiotemporal oxygen concentration patterns were estimated. This work filled the gaps in the measurement and research of oxygen concentrations on the QTP while providing data support for analyses of the influencing factors and spatiotemporal characteristics of oxygen concentrations, which is of great significance for promoting the construction of ecological civilization in the QTP region.
Glacial-Holocene variability in sediment accumulation and erosion along submarine blind canyons: a case study from Eastern Mediterranean Sea 
Authors: Katz Oded , Moshe Naomi , Torfstein Adi , Kanari Mor , Masque Pere , Hyams-Kaphzan Orit
Published: March 2024

Submarine canyons serve as important sediment transport conduits from littoral zones to the deep sea, with strong impacts on the sedimentation patterns in marginal areas of the ocean. Here, we present a study of the geological history and the recent activity of the Nahariya submarine canyon, the longest of a system of ~15 small blind canyons located in the eastern Mediterranean Sea, offshore Israel. Two piston cores retrieved from the middle and outlet of the canyon, at 650 m and 915 m water depth, respectively, were the focus of a multi-proxy study aiming to characterize sediment transport and deposition along the canyon during the Last Glacial and up to the present.Both cores reveal a sequence of homogenous sediment of late last glacial age, which are capped by an unconformity overlying by fine laminated sediment dated to the last ~200 years. Thus, the deglacial and most of the Holocene intervals are absent from the record. Evidence for down canyon sediment transport are abundant and include a 70 cm interval of mud clasts with disordered glacial ages that appears immediately below the hiatus, as well as broken calcareous shells of dead benthic foraminiferal species of shallow marine habitats, which are abundant throughout both cores. Similarly, shelf-derived living benthic foraminiferal species were found in the core-tops, indicating that active sediment transport persists along this canyon today.We conclude that the history of Nahariya submarine canyon includes a period of sediment accumulation that lasted until the last deglaciation. Thereafter, the canyon was dominated by an erosive regime that persisted throughout the Holocene. Sediment accumulation resumed ~200 years ago. We suggest that the recent resumption of sediment-accumulation is a result of anthropogenic amplification of on-land soil erosion accompanied by a wet period that persisted in the region and enhanced land to sea sediment transport.
Land degradation due to soil erosion in the Mediterranean olive groves: A comparison of 137Cs, 239+240Pu radionuclides and 3D reconstruction of surface levels
Authors: Moreno Romero Gabriela , Alewell Christine , Borrelli Pasquale
Published: March 2024

Olive tree plantations, an ancient and traditional crop in the Mediterranean region, have become erosion-prone due to their soil management and location. Many olive groves are often planted on slopes, where soil management often keeps the soil bare by conventional tillage and/or herbicide use. Further, the natural conditions of the region as long drought periods followed by intensive rainfall episodes, intensify the susceptibility to erosion. As a result of these factors, soil erosion has become a major threat to the sustainability of olive cultivation in southern Spain.On-site soil erosion measurements through conventional methods usually do not exceed one decade and present several discrepancies among them and with modelling outcomes. Here, we aim to use fallout radionuclide (FRN) inventories (137Cs, 239+240Pu) together with 3D reconstruction of surface levels to estimate soil erosion rates at appropriate temporal and spatial scales for the last 55-60 years and/or from the beginning of tree plantation. Twelve soil cores up to 40 cm depth were taken across olive groves and in identified reference sites, and the model MODERN (Modelling Deposition and Erosion rates with RadioNuclides) (Arata et al., 2016) was used to estimate soil erosion rates from 1960. For the geomorphological reconstruction, manual measurements were taken to recreate the historical soil surface using the germination point in the olive trees as a reference point to the current soil surface. Both methods allowed us to estimate and understand past erosion processes and possible long-term trends.The radiochemical analysis content of 137Cs, 239+240Pu inventories and its correlation with a geomorphological reconstruction on selected olive tree fields under different soil management in southern Spain will be presented. Arata, L., Meusburger, K., Frenkel, E., A’Campo-Neuen, A., Iurian, A.-R., Ketterer, M. E., Mabit, L., & Alewell, C. (2016). Modelling Deposition and Erosion rates with RadioNuclides (MODERN) – Part 1: A new conversion model to derive soil redistribution rates from inventories of fallout radionuclides. Journal of Environmental Radioactivity, 162–163, 45–55. https://doi.org/10.1016/j.jenvrad.2016.05.008