bluuebunny/crossref_metadata_2025 huggingface dataset:
From research to outreach – an example from the Smøla island, Mid-Norway
Authors: Venvik Guri , Nordgulen Øystein , Hodge Matthew , Barkaas Garseth Eline , Osmundsen Per Terje
Published: March 2024

The BASE project, short for Basement Fracturing and Weathering on- and offshore Norway, is a research project funded by the Norwegian Research Council. While the project`s primary focus has been on disseminating its findings through scientific channels, there is growing interest emerging from local communities and schools. After several seasons of extensive fieldwork and a comprehensive core drilling campaign, we have observed an increased local curiosity and interest, particularly regarding the "why" and "what" behind our efforts. In our quest to synthesize the wealth of collected data, our goal is to contribute to a local geological exhibition showcasing updated bedrock information and delivering a compelling geological narrative of the Smøla island. This exhibition will illuminate the age of the rocks, the processes that formed them, and unravel the intricate story they convey. Our fieldwork has uncovered remarkable geological outcrops, which we believe should be shared with the broader community. In collaboration with the local “Friluftsliv” (outdoor life) community, we plan to create stops along their popular “Stikk UT!” routes. These routes and paths are clearly marked on maps and equipped with informative signs. We plan to incorporate geological insights about selected outcrops to enrich the experience for those who visit this remarkable area. Furthermore, in addition to our outreach efforts, we are dedicated to making our research relevant for primary and secondary school, with specific focus on 5th and 8th -grade pupils studying geology as part of their curriculum. To achieve this, we will employ a comprehensive approach that includes interactive storytelling on the Geological Surveys website, Geologisk arv (ngu.no) (Geoheritage), and we will provide ample information to teachers. By combining these strategies, our aim is not only to make geology accessible, but also to make it attractive and fascinating for the 5thand 8th -grade pupils. We hope to inspire the next generation of geologists and curious minds based on the captivating geological history of Smøla.  References (format style Heading)Geologisk arv (ngu.no)Stikk UT!
Impacts of the Three Gorges Dam on regional precipitation: based on high resolution simulation
Authors: Peng Peiyi , Zhang Yiming , Di Xu
Published: March 2024

The Three Gorges Dam (TGD), as the largest hydropower project, resulting in increasing water area from 408km2 to 1084km2 and extending waterway into 660 km. It is obvious that land use change would influence regional precipitation, but affected region owing to the TGD is on dispute. Moreover, the highest resolution of previous studies is 1.5 km, however the width of artificial lake formed by the TGD is about 1.1 km. To this end, we address the need of a higher resolution of numerical simulation by running weather research and forecast (WRF) model with 3 two-way nested domains. Two simulations under different land use (with or without TGD) are compared. Results showed that regional precipitation is suppressed owing to TGD to some extent. More precisely, increasing precipitation happens in downwind region, whereas decreasing precipitation occurs upwind region. Besides, water surface expansion leads to a reduction in surface temperature within 0~5 km of surrounding area. The TGD construction increase specific humidity and surface within 5 km buffer. That is because water surface expansion results in moisture surplus in nearby region.
Phase mixtures in shear zones
Authors: Kilian Rüdiger
Published: March 2024

Deformation of polymineralic rocks at elevated temperatures usually results in grain size refinement but also in a grain scale mixture of mineral phases. Phase mixtures may either be homogeneous or exhibit a compositional and microstructural layering. Depending on the host rock stability, mixtures may consist of combinations of redistributed or newly, synkinematically formed phases. In general either neighbour-switching or heterogeneous nucleation are envisaged as processes responsible for mixing during diffusion creep s.l. including grain boundary sliding and grain-scale transport processes. In order to quantify phase mixtures, neighbourhood relations can be analysed to differentiate random, clustered or anti-clustered distributions. Heterogeneous nucleation is usually considered to allow for anti-clustered distributions, while neighbour switching during grain boundary sliding potentially produces random distributions.Here, phase mixing is explored based on contact densities as well as on centre-to-centre distances. In particular, the effect of directionality that is neighbour relations as a function of the relative position in a 2D section is considered. The direction of neighbours is considered by the normal of the boundary trace as well as alternatively, by the direction of the centre-to-centre join.Given sufficiently large datasets and non-extreme mixtures (e.g. with 0.2 < phase proportion < 0.8) a confidence interval of the results can be defined. Large datasets of ultramylonites of different metamorphic grade, phase proportions, compositions (ultramafic, mafic, quartzo-feldspatic) and microstructures (layered, isotropic) are tested.It is found that phase anti-clustering is generally more pronounced in a direction close to the stretching direction in either layered or homogeneous ultramylonites. In layered mylonites, layer-normal relations are frequently found to be random while intralayer relations are often anti-clustered.In the different rock types, specific anti-clustered phases can be discriminated, e.g., orthopyroxene with respect to olivine, k-feldspar with respect to plagioclase and quartz, and hornblende with respect to plagioclase. Other phase assemblages e.g. quartz-plagioclase are frequently found to be distributed randomly, hinting at mineral specific roles during diffusion creep s.l. and generally at element mobilities in deforming metamorphic rocks.
Modelling near-Sun solar wind electron distribution functions
Authors: Micera Alfredo , Verscharen Daniel , Coburn Jesse , Halekas Jasper , Innocenti Maria Elena
Published: March 2024

We provide a picture of the global dynamics of electrons in the inner heliosphere through the study of non-linear interactions affecting the non-thermal features of the solar wind electron velocity distribution function (VDF).More than 50 years of in-situ observations of the solar wind have shown that the electron VDF consists of a quasi-Maxwellian core, comprising most of the electrons, and two sparser components, the halo, which is formed by suprathermal and quasi-isotropic electrons, and an escaping beam population, the strahl (Marsch 2006; Halekas et al. 2020).Recent Parker Solar Probe and Solar Orbiter (SO) observations have confirmed the existence of an additional non-thermal feature: the deficit, i.e., a depletion in the sunward region of the VDF (Berčič et al., 2021a; Halekas et al., 2021). This feature had already been predicted by exospheric models (Lemaire and Scherer, 1971; Maksimovic et al., 2001).By employing Particle-in-Cell (PIC) simulations, we study electron VDFs that reproduce those typically observed in the inner heliosphere and investigate how the electron deficit contributes to the onset of kinetic instabilities and to heat flux regulation in the solar wind.The strahl electrons drive oblique whistler waves unstable which scatter them in turn (Verscharen et al., 2019, Micera et al., 2021). Our simulation results show that, as a consequence of these scattering processes, the suprathemral electrons occupy regions of phase space where they fulfil resonance conditions with the parallel-propagating fast-magnetosonic/whistler wave.The suprathermal electrons lose kinetic energy, resulting in the generation of unstable waves. The sunward side of the VDF, initially depleted of electrons, is thus gradually filled by electrons that are resonant with the triggered whistler waves.As this initial deviation from thermodynamic equilibrium is reduced, a decrease in the electron heat flux occurs.Our study provides a mechanism that explains the presence of the regularly observed parallel sunward whistler waves in the heliosphere (Tong et al., 2019), whose origin remains uncertain (Vasko et al., 2020). It also suggests an explanation for recent SO observations of whistler waves, concomitant with distributions in which the three above-described non-thermal features are observed (Berčič et al., 2021b, Coburn et al., 2023).
A meso-scale simulation of future household and commercial water use under socio-economic and climatic scenarios in Thuringia
Authors: Werner Simon , Klassert Christian , Klauer Bernd , Gawel Erik
Published: March 2024

Understanding water use conflicts and anticipating their possible future trajectories requires knowledge of the drivers of household and commercial water use. Water demand is primarily shaped by long-term demographic and socio-economic trends, alongside seasonal fluctuations in weather, which are susceptible to the impacts of climate change. Because the availability of water resources and their use by the various economic sectors are spatially very heterogeneous, it is necessary to use spatially explicit models to investigate water conflicts, which differentiate in particular between rural and urban regions. Here we simulate the regional water use of households and commercial enterprises for the Free State of Thuringia at a high spatial resolution. The model is based on household water demand functions for representative household types and regions.  The household and communal water use is then simulated based on local characteristics of each supply area. The model distinguishes between base water demand, which is explained by socio-demographic factors, and seasonal water demand, which is explained by weather factors. To parametrize the model, we use various regression techniques with public data, and daily water discharge of representative suppliers. Our results show different trajectories of water consumption quantities. Thereby we combine socio-demographic scenarios using statistically downscaled Shared Socio-Economic Pathways and climate scenarios using Regionalized Concentration Pathways. We provide a range of different distributions of water use patterns in Thuringia, informing decision makers about integrated water management options and the effect of demand-side policy measures such as tariffs. 
Effect of velocity fluctuations on pore scale stretching kinematics in 3D porous media
Authors: Maeritz Manuel , Heyman Joris , Le Borgne Tanguy , Dentz Marco
Published: March 2024

Fluid stretching plays an important role in controlling mixing dynamics in porous media. Recent advances have shown that stretching at pore scale in 3D porous media is chaotic, leading to exponential elongation of mixing interfaces [e.g. 1,2]. Yet, it is not known how the associated stretching rate depend on the pore scale velocity heterogeneity. In this study, we perform particle tracking simulations in a periodic flow fields to investigate how flow heterogeneity control the transient evolution of the stretching rate as well as the asymptotic stretching rate (Lyapunov exponent). Our results reveal that rare low velocity events have a significant impact on the Lyapunov exponent, while these regions are numerically more difficult to treat and thus sometimes excluded from statistics [1]. Moreover, we discuss conceptual difficulties associated to velocity pdf with heavy tails towards low velocities: Ensemble averages of the deformation gradient tensor do not converge under these conditions when taken them at equal advective distances, as opposed to at equal times. As a consequence, the meaning of the steady state stretching rate must be discussed in the context of long memories. Using Continuous Time Random Walks (CTRW) we derive analytical expressions for the averages and discuss low velocity cutoffs to guarantee convergence. We further discuss the nature of the pre-asymptotic stretching kinematics, which can have a dominant effect on mixing processes. We show that the strength of the transient is controlled by the typical shear rate while the duration is determined by the Lyapunov exponent. Weaker chaotic stretching are associated to a longer lasting transient regime.[1]: Turuban et al. (2019) In: JFM [2]: Heyman et al. (2020) In: PNAS
Nature-based Solutions in vineyards of Oltrepò Pavese (Northern Italy): state of the art and analysis of their effectiveness in shallow landslide mitigation 
Authors: Gambarani Antonio , Vercesi Alberto , Bordoni Massimiliano , Giarola Alessia , Vivaldi Valerio , Meisina Claudia
Published: March 2024

Land degradation, e.g. shallow landslides, with correlated soil loss and nutrient loss, is a significant environmental problem for the agroecosystems, especially where farming is carried out on sloping soil (e.g. vineyards, olive groves, etc.).Due to climate change and consequent increase on extreme weather events, these processes are likely to become more widespread, thus leading to significant land abandonment.Another factor affecting land degradation concerns soil tillage by agricultural machinery, which, if uncontrolled, can accelerate the development of these processes.Land degradation is also dangerous for rural communities because of its rapidity of initiation and development and the lack of warning signs for its detection. It is therefore necessary to apply in agroecosystems effective solutions for disaster risk reduction (DRR) which, at the same time, are of low environmental impact and economically sustainable. Nature-based Solutions (NbS) can help address all these challenges as they are widely recognized by the scientific community and are often funded by countries or the union of countries, such as the European Union or the United Nations. However, NbS are still poorly applied by farmers and local governments, favoring gray infrastructure measures that are sometimes ineffective at achieving land degradation neutrality.The aim of this work is to produce an inventory of the Nature-based Solutions applied in vineyards in an Apennine area of Northern Italy in order to verify, at the slope scale, their effectiveness in the mitigation of shallow landslides. The study area is represented by a sector of Oltrepò Pavese, one of the most important agricultural and viticultural regions in Italy.In the last 15 years, more than 2000 shallow landslides were triggered in consequence of intense rainfall events, with a density of distribution which reached more than 40% of the territory cultivated with grapevines. The work is carried out in the context of a PhD project, financed with PNRR (National Recovery and Resilience Plan) and cofounded by seven municipalities, stakeholders of the project. The final aim of the PhD projectis to identify the most suitable NbS for the studied area, in terms of technical and economical suitability. The scientific research results will be incorporated within the municipal planning tools and rural police regulation in order to prevent shallow landslides.
Assessing the impact of stress–dependent hydraulic properties on hillslope-scale groundwater flow and transport
Authors: Figueroa Ronny , Roques Clément , Abherve Ronan , Halloran Landon , Valley Benoit
Published: March 2024

The occurrence of springs and their connectivity within stream networks is typically associated with three key controlling factors: climate, topography and the distribution of hydraulic properties. In crystalline media, this distribution is often related to lithology and the presence of fractures. In addition, tectonic and topographic stresses can modify properties through compressive and extensional forces acting on the rock mass and fractures. However, these controls are rarely considered for hillslope scale applications. The aim of this research is to investigate the effects of stress on bedrock hydraulic properties and their implications for groundwater flow and transport at the hillslope scale. A numerical experiment has been designed that combines linear poroelasticity to simulate the distribution of permeability and porosity, together with groundwater flow and transport simulations. Different slope and stress conditions are examined, providing a comprehensive sensitivity analysis framework.Our results show that vertical stress leads to a decrease in permeability and porosity at depth, following an exponential-like trend. Increasing the proportion of lateral stresses relative to the total vertical stresses reduces the mean permeability and porosity and increases the variance in the distribution along the hillslope. For high values of lateral stress, a low permeability domain develops downslope at the valley bottom due to the accumulation of compressive stresses, while the extensive regime at the crest provides higher permeabilities. As expected, groundwater flow simulations revealed that the partitioning of flow paths is strongly influenced by such heterogeneous stress-induced permeability and porosity fields. As stress increases, groundwater flow becomes more channelized in the near subsurface, strongly deviating from the classical Dupuit model. We also found that the distribution of normalized groundwater discharge rates shows higher values in the upper part of the seepage zone than in the lower part. By analyzing the results of particle tracking simulations, we found that mean residence times increase with higher external stress due to a decrease in mean permeability. In addition, the shape of the residence time distribution is strongly modified by the channeling of groundwater flow with increasing lateral stress, with the probability of shorter residence times increasing as stress increases. We discuss the implications of these fundamental results for our understanding of the role of stress in groundwater-dependent systems, with important insights into the recharge, storage and discharge mechanisms that may control the resilience of landscapes to the effects of climate change.
A complete feature set for classification of seismic sources with Distributed Acoustic Sensing (DAS) in the context of long-range monitoring
Authors: Huynh Camille , Hibert Clément , Jestin Camille , Malet Jean-Philippe , Lanticq Vincent
Published: March 2024

Distributed Acoustic Sensing (DAS) exploits Rayleigh light backscattering to extract images of seismic wave propagation along a fiber optic in time and distance. The spatial distribution of virtual point sensors represents an opportunity to develop innovative methods for seismic event sources detection and identification. We develop in this study a method based on Machine Learning solutions for events classification.This method relies on the development of features which translate the characteristics of the signals we observe into quantities that can be processed by machine learning algorithms to achieve the source classification. Three families of features investigating temporal and spatial characteristics and similarity of the signal are proposed, such as spatial and temporal analysis of the standard deviation, kurtosis or skewness of the signal or cross-correlation and dynamic time warping characterization and enables to quantify their individual contribution. Then we use a supervised machine learning model named XGBoost to perform classification based on these developed features. We tested this approach with a dataset recorded along a 91 km-long fiber optic deployed in the Pyrenees in France. The data acquisition has been achieved using a FEBUS A1-R DAS interrogator and with the support of TotalEnergies, from August 30 to September 20, 2022. During this period, 11 earthquakes and 6 quarry blasts have been recorded.The trained model is validated using cross-validation techniques. Our Machine Learning processing chain successfully detect and classify 13 regional events from continuous background noise made by natural and anthropogenic activities. In particular, spatial features help to reduce the contribution of moving vehicles, whose presence is unavoidable along existing long-distance telecommunication fiber sections installed alongside roads.  In the continuity of this study, we investigate the potential of transfer learning from geophones deployed along the studied cable to DAS data or to another fiber optic cable installed in the same area.
Spontaneous strain localisation in a viscoelastic material owing to thermal softening 
Authors: Utkin Ivan
Published: March 2024

Numerous studies emphasize the significance of thermal softening induced by shear heating and the concurrent generation of ductile shear zones in geological processes spanning various spatial and temporal scales. Thermal softening is proposed as a primary mechanism in the formation of tectonic plate boundaries and as a potential mechanism of intermediate-depth and deep-focused earthquakes, where large confining pressure inhibits brittle fracture. In the latter scenario, seismic velocities during shearing are achieved through the spontaneous viscous dissipation of stored elastic energy, a phenomenon known as self-localizing thermal runaway (SLTR) [1].Resolving SLTR poses a formidable numerical challenge due to the multiscale nature of the process. The slow initial stage of differential stress buildup and strain localization is succeeded by the rapid development of a thin shear zone, necessitating high spatial and temporal resolution. Prior numerical studies of self-localizing thermal runaway were confined to 1D, restricting applications to less realistic geometries and simpler model setups.In this study, we explore the viscoelastic effects of spontaneous flow localization through numerical modeling in 2D. We develop a fully coupled thermo-mechanical solver utilizing a novel conservative energy formulation. Our work demonstrates the potential for SLTR instability in various 2D model setups. Through systematic numerical experiments, we compare the onset of localization with 1D predictions. Additionally, we investigate the role of heterogeneities in the distribution of material properties on the development of a ductile shear zone.[1] Braeck, S., & Podladchikov, Y. Y. (2007). Spontaneous thermal runaway as an ultimate failure mechanism of materials. Physical Review Letters, 98(9), 095504.
Geometric amplification and suppression of ice-shelf basal melt in West Antarctica
Authors: De Rydt Jan , Naughten Kaitlin
Published: March 2024

Ice shelves along the Amundsen Sea coastline in West Antarctica are continuing to thin, albeit at a decelerating rate, whilst ice discharge across the grounding lines has been observed to increase by up to 100% since the early 1990s. Here, the ongoing and future evolution of ice-shelf mass balance components (basal melt, grounding line flux, calving flux) is assessed in a high-resolution coupled ice-ocean model that includes the Pine Island, Thwaites, Crosson and Dotson ice shelves. For a range of idealized ocean-forcing scenarios, the combined evolution of ice-shelf geometry and basal melt rates is simulated over a 200-year period. For all ice-shelf cavities, a reconfiguration of the 3D ocean circulation in response to changes in cavity geometry is found to cause significant and sustained changes in basal melt rate, ranging from a 75% decrease up to a 75% increase near the grounding lines, irrespective of the far-field ocean conditions. These poorly explored feedbacks between changes in ice-shelf geometry, ocean circulation and basal melting have a demonstrable impact on the net ice-shelf mass balance, including grounding line discharge, at multidecadal timescales. They should be considered in future projections of Antarctic mass loss, alongside changes in ice-shelf melt due to anthropogenic trends in the ocean temperature and salinity.
Unlocking Insights in Historic Tidal Records with Analysis Methods Tailored to High-Low Tidal Data
Authors: Beemster Joris , Torfs Paul , Hoitink Ton
Published: March 2024

Water-level measurements, sometimes spanning centuries, offer a valuable historical perspective. Although contemporary tidal data is collected digitally at high frequencies, historical records often merely consist of basic high and low water levels. Recognizing the value of these low-resolution tidal records, recent 'data rescue efforts' focus on digitizing and preserving them. Current tidal analysis methods, optimized for high-frequency data, fall short in exploiting the potential of high- and low-water observations.Here, we introduce a specialized tidal analysis methodology tailored for high- and low-water observations. Leveraging equilibrium tide information and the unique characteristics of these observations, such as a derivative constraint, we enhance the analysis of historical records. Additionally, we explore interpolation methods for high- and low-water observations, aiming to address the possibilities and limitations associated with these data.Our approach has the potential to offer valuable insights into century-scale water level changes, and to unravel the contributions by tides, river discharge, mean sea level, storm surges and interactions among those governing factors to water level variation. A key ambition we have is to reveal the hydrodynamic consequences of human interventions, which are difficult to distinguish from each other. We hope the new technique will encourage to continue digitization of historic high-low-tidal observations, and allow to demonstrate the role of intertidal areas in modulating water level extremes.
Investigating the sensitivity of flux maps in simulating radon concentrations at greenhouse gas monitoring sites
Authors: Howes Adam , Kikaj Dafina , Chung Edward , Karstens Ute , Manning Alistair , Henne Stephan , Wenger Angelina , Foster Grant , O'Doherty Simon , Rennick Chris , Arnold Tim
Published: March 2024

Given its unique properties as a radioactive chemically inert gas, radon can act as a valuable atmospheric tracer, for evaluating the performance of atmospheric transport models to calculate the sources of trace gases to the atmosphere. A radon flux map is the scientific starting point for simulating atmospheric radon concentrations using atmospheric transport models. As such, it is important to assess the available high resolution radon flux maps to ensure that simulated concentrations can be accurately interpreted. The spatial fluxes of radon primarily depend on soil and rock types, while temporal variations are influenced by soil moisture content.The recent advancements in generating two high-resolution radon flux maps for Europe using two different soil moisture reanalysis, GLDAS Noah and the ERA5 maps1, have significantly enhanced our understanding of radon flux dynamics. Yet, the radon flux values diverge notably between these two maps and sometimes these variations can be substantial, with differences as large as the absolute radon flux itself.In our work, two available versions of European radon flux maps are coupled with two Lagranian particle dispersion models – the Met Office’s Numerical Atmospheric Modelling Environment (NAME) and the FLEXPART model – are used to simulate radon concentrations measured at four tall tower sites in the United Kingdom: Heathfield, Ridge Hill, Tacolneston and Weybourne. We calculate the differences between the modelled radon concentrations to the observed radon concentrations at these sites and use this to investigate the sensitivity of two radon flux maps: GLDAS Noah and ERA5. References: 12022: https://doi.org/10.18160/2ST9-3NAD
Enhancing Environmental Monitoring in Poland: Leveraging Sentinel Satellite Data through the CAMS National Collaboration Programme
Authors: Przeździecki Karol , Strużewska Joanna , Kamiński Jacek , Jeleniewicz Grzegorz , Mochocki Damian , Kawka Marcin
Published: March 2024

Copernicus provides a wide variety of services covering different topics, starting from Atmosphere through Marine, Land, Climate Change, Security and Emergency.Satellite observations on atmospheric composition, complementary to Copernicus Atmosphere Monitoring Service (CAMS), become increasingly available. Unfortunately, analysis or even opening of satellite data in their native formats prove to be challenging in communities other than scientific.Functionalities, data products, and analysis provided to users on the CAMS website are mainly at the global and European scales. It has been recognized that usage of those services and data they provided by Member States are rather unsatisfactory. Therefore, ECWF prepared CAMS National Collaboration Programmes for member states to improve the uptake of CAMS products at the national, regional and local levels, responding to regulatory needs coming from public administration, NGO's and other interested parties. Institute of Environmental Protection – National Research Institute is responsible for the provision and development of the CAMS National Collaboration Programme for Poland.We will present the usage of prepared averaged products derived from Sentinel 5P AER AI, Sentinel 5P NO2, and S5P HCHO data in investigating transport episodes connected with wildfires or desert dust over the Polish region. We have investigated data from 2019 to 2023 for both RPRO and OFFL Sentinel 5P products.We will also discuss the potential usage of other products being tailored and developed during the CAMS NCP Poland project, which have been indicated during the preliminary communication phase via survey  and discussion on 1-st User and stakeholder meeting. The study's outcome would also be important for the HE CAMEO project, where we investigate potential benefits from the assimilation of satellite data to the regional models.
Comparing and combining directional swell measurements from Sentinel-1, SWIM and SWOT
Authors: Husson Romain , Ollivier Annabelle , Molero Beatriz , Peureux Charles , Gombert Baptiste , Yassine Manal , Dubois Pierre , Nigou Adrien , Aouf Lotfi , Tourain Cedric , Dibarboure Gérald , Bohé Alejandro
Published: March 2024

 

Various spaceborne Radar instruments are now operating with the common ability to observe long waves propagating across the oceans: the C-band Synthetic Aperture Radar (SAR) onboard Sentinel-1 (~23-36° of incidence), SWIM rotating Ku-band Radar onboard the Chinese-French CFOSAT satellite (~2 to 10° of incidence) and the Ka-band radar Interferometer (KaRIn) onboard the Surface Water Ocean Topography (SWOT) (1 to 5° of incidence).  

The directional swell measurements are investigated using model and in situ measurements but also co-locations between the spaceborne instruments (also known as cross-overs in altimetry). These latter co-locations involve both static and so-called “dynamic co-locations" where waves are propagated using a linear wave propagation model over a few hundred kilometers to maximize the number of co-locations between the sensors. Intercomparisons can therefore be performed either for specific case studies or for massive statistical comparisons. 

In this study, we use wave measurements from Sentinel-1A (S1-A) wave mode Level-2 Ocean (OCN) products (distributed by ESA) and SWIM L2P products from the new Near-Real Time (NRT) processing that extends the range of swell measurements up to 1200m wavelength (500m before) and better filter non-wave signatures (distributed by CNES/CLS, Q1 2024). We also investigate the possibility to use KaRIn SWOT spectral content of measurements from either the Sigma0 or the Sea Surface Height Anomaly (SSHA) observations to image so-called “forerunners”, the longest period swells that propagate ahead of the most energetic swell components (from Munk 1947). 

Intercomparisons show the promising synergies between these sensors and the potential to derive worldwide multi-sensor swell monitoring. First, SWIM shows great capabilities to image the shortest swell that S1 can totally miss or partially image because of its cutoff limitation. Then, S1 has shown capabilities to observe long swell (with peak wavelength larger than 800m), but their imaging mechanism is still limited by the reduced velocity bunching and tilt modulation of longest forerunners. On the other hand, comparisons with SWOT indicate that KaRIn unsmoothed (ocean data at their highest resolution) SSHA measurements can further extend the range of visible swell up to kilometric scales thanks to its interferometric capability. 

A significant work is still necessary to better understand, compare and inter-calibrate these directional swell measurements but they offer very promising perspectives for the exhaustive description of swell events, from the longest forerunners to the short wind sea. 
Tracking shallow groundwater response to a pumping test using a dense passive seismic array 
Authors: Baudement Cécile , Guillemot Antoine , Larose Eric , Garambois Stéphane , Royer Alexandra , Rey Etienne , Cappoen Vincent
Published: March 2024

Facing the societal issues related to water resources management, the development of ambient noise-based seismology for monitoring fluids in the subsurface is promising but still challenging (1). In this study, we propose a seismological monitoring of shallow groundwater with high spatial resolution, by applying ambient noise interferometry techniques. On a glacio-alluvial plain containing a shallow aquifer near Grenoble (France), we installed a dense array of 50 seismic nodes settled during five days. A pumping test was performed in a borehole during the experiment, inducing a fast and heterogeneous response of the aquifer. We estimated relative changes in surface wave velocity (dV/V) from autocorrelations of ambient noise recorded by the 50 sensors. During the pumping phase, dV/V increases by more than 10% near the borehole, indicating a significant decrease in pore pressure. Mapping the seismological response to pumping suggests a high channelization of the hydrogeological paths. Poroelastic modeling combined with active seismic campaigns improves the interpretation of observations (2), paving the way to a high-resolution time-lapse 3D mapping of the water dome and potential fluxes.References1 - Gaubert‐Bastide, T., Garambois, S., Bordes, C., Voisin, C., Oxarango, L., Brito, D., & Roux, P. (2022). High‐resolution monitoring of controlled water table variations from dense seismic‐noise acquisitions. Water Resources Research, 58(8), e2021WR030680.2 - Voisin, C., Garambois, S., Massey, C., & Brossier, R. (2016). Seismic noise monitoring of the water table in a deep-seated, slow-moving landslide. Interpretation, 4(3), SJ67-SJ76.
Landscape response at the edge of a tearing slab
Authors: Azañon Jose Miguel , Galve Jorge Pedro , Ballesteros Daniel , Perez-Peña Jose Vicente , Ruano Patricia , Garcia-Garcia Fernando , Booth-Rea Guillermo
Published: March 2024

Tearing at the edges of subducted slabs permits the migration of narrow orogenic arcs. Dynamic models predict that the active segment of subvertical tears migrates in the sense opposite subduction modifying the topography and tectonic regime along its path. However, the effects of slab tearing on surface deformation and landscape evolution, remains virtually unexplored. Here we show the landscape response to slab tearing, including drainage development and reorganization in the Betics, with analogies to the southern Caribbean arc. After approximately 400 km of slab tearing since 10 Ma the Betics show a transient topography with positive residual values over regions stripped from their subcontinental lithospheric mantle and negative anomalies outboard of the tear. The landscape evolves through crustal shortening and flexural uplift in the foreland of the active tearing segment producing land emergence and drainage development, with fluvial diversion around uplifting structures. Slab pull and orogen transverse extension inboard the active-tearing segment foster basin development followed by emergence and drainage reorganization by fluvial incision and capture. Mantle upwelling, flexural rebound and further extension affects teared regions, driving positive residual topography amplified in the footwall of extensional domes. Mantle flow around the slab drives uplift hundreds of km away from the slab edges.
The Best of Both Worlds – Combining a Revised Global River Model to In-Situ River Plastic Transport Data
Authors: Ebner Ronja , Mani Thomas , Lebreton Laurent
Published: March 2024

To tackle the accumulation of plastic in the open oceans and along the shorelines, it is necessary to identify and understand its input paths. With more than 4smaller coastal systems draining into the global oceans, this is a complex task. A global model representing a plethora of different systems is one way to approach this problem.For this purpose we improved the global river model presented in Meijer et al., 2021 which is using multiple datasets such as topography, land cover, runoff, precipitation, wind, population density, landfills, dams and mismanaged plastic waste per country to estimate the magnitude of the input of plastic into the oceans. This is achieved by a mouth-2-source algorithm that originates from each river mouth. How far the influence of a given network reaches inland is dependent on the discharge within it and is parametrized with an abstract, global parameter, γ. The value of the latter can be calibrated using an analysis of both Eulerian and Lagrangian in-situ river plastic transport data from different river systems worldwide.Our analysis highlights the importance of plastic transport experiments with high data-density. The model results put the global plastic input into the ocean close to 500 kt/yr and indicate that the influence of the numerous smaller coastal catchments needs to be taken into account  With this model we are further able to identify river systems that interesting for targeted action.
Impact of Wind Stress Curl on the Eddy Saturation of the Antarctic Circumpolar Current from a Barotropic Perspective
Authors: Dogan Sima , Muller Caroline , Nadeau Louis-Philippe , Venaille Antoine
Published: March 2024

Eddy saturation, a phenomenon where east-west transport remains insensitive to changes in wind stress, is believed to play a crucial role in explaining the behavior of the Antarctic Circumpolar Current (ACC). Two distinct mechanisms are known to lead to eddy saturation: (i) baroclinic instability in stratified flows and (ii) topographic-barotropic instability in unstratified flows. This study focuses on eddy saturation resulting from topographic-barotropic instability in a doubly periodic domain. Previous findings have shown that topographic-barotropic instability, typically occurring within a specific range of wind stress, is significantly influenced by the geometry of the topography. We investigate how the introduction of wind stress curl affects the occurrence and the dynamics of eddy saturation. Our findings demonstrate that wind stress curl and its interaction with topography is crucial in understanding the eddy saturation and, consequently, for determining the zonal transport of the ACC. In the doubly periodic domain, a dependence is observed between the zonal transport and the wind stress variations in relation to mean wind stress,  associated with the form stress composed by the interaction with bottom topography with singular and multiple ridges.
Microwave scattering in the Antarctic megadunes region: reconciling radar and radiometry
Authors: Bonnefoy Lea , Prigent Catherine , Picard Ghislain , Soriot Clément , Kilic Lise , Jimenez Carlos
Published: March 2024

Icy surfaces across the solar system display unusual microwave radar and radiometry properties, including very high backscattering cross-sections and polarization ratios. At low temperature, snow and ice are very transparent to microwaves, leading to long path lengths and multiple scattering. Yet despite the large volume of available passive and active microwave satellite observations over the Earth cryosphere, physical interpretation of the co-variability of the multi-frequency observations is still challenging, especially when trying to reconcile radiometry and radar observations. To shed light on microwave scattering in icy regoliths, we focus on the Antarctic megadunes region, the coldest and driest area on Earth, which we propose as a new analog for icy satellites due to its very low precipitation (net zero snow accumulation) and temperature (averaging -50°C), combined with the highest microwave backscatter in Antarctica. We assemble a dataset consisting of 5.2 GHz ASCAT and 13.4 GHz QuikSCAT and OSCAT scatterometry, as well as AMSR2 radiometry at 6.9 to 89 GHz. Using the Snow Microwave Radiative Transfer (SMRT) model with a simplified snowpack with constant temperature and continuously increasing grain size and density with depth, we simulate simultaneously radar and radiometry. For the first time, we show that scatterometry and 6.9 to 37 GHz radiometry at V polarization can be successfully simulated with a unique simple snowpack model, indicating that incoherent volume scattering on subsurface heterogeneities dominates both the active and passive signal. The success of our approach encourages further work to analyze and simulate jointly active and passive microwave observations, both in the Earth cryosphere and on icy moons.
Assessing daily to interannual geocenter motion variations from Low Earth Orbiters
Authors: Couhert Alexandre , Mercier Flavien , Moyard John , Exertier Pierre
Published: March 2024

The ever-changing fluid mass (oceans, continental water, snow, atmosphere, …) redistributions on the Earth's surface give rise to a motion of the deformable terrestrial crust, that is its geometrical center-of-figure (CF), with respect to the center-of-mass (CM) of the Earth, about which satellites naturally orbit. This motion, called “geocenter motion”, is the largest scale variability of mass within the Earth system. Yet, non-tidal geocenter motion, which reflects major water and atmosphere mass transports occurring over large regions, is traditionally neglected.However, new climate-driven precise monitoring of geocenter motion is needed. Indeed, satellite altimetry and gravimetry precise orbits connect sea level and global water budgets to the Earth’s center of mass. As such, the geocenter motion is now the leading error term in Regional Mean Sea Level and mass changes over polar ice sheets estimates. Reliable solutions of geocenter motion are thus crucial for assessing the current status of climate change and its future evolution (e.g., for the Earth’s Energy Imbalance).Global Navigation Satellite Systems (GNSS) measurement models and derived products are currently aligned to the International Terrestrial Reference Frame (ITRF) origin (which is referenced to the crust), instead of CM. Looking at sub-daily cross-track perturbations estimated with the GNSS receivers on board the Jason-3 and Sentinel-6 MF altimetry satellites during their tandem phase (December 18, 2020 – April 7, 2022) revealed consistent diurnal oscillations with an impressive temporal resolution. These could only be related to the miscentering effect of the constellation solution around the Earth’ CM. In this paper, a parametric model is derived, representing the translation of the GNSS ground station networks with respect to the center of mass of the whole Earth system. This model is estimated with GNSS-based low Earth satellite precise orbits and unambiguously validated with independent altimetry satellite missions (e.g., Sentinel-3A, Sentinel-6 MF, Jason-3). It helps to clearly identify interannual variations in the geocenter motion, as short as a day long.
Biological processes and wind contributions to 3-D fine-scale dynamics in a coastal area
Authors: Arnaud Maxime , Petrenko Anne , Fuda Jean-Luc , Comby Caroline , Bosse Anthony , Ourmières Yann , Barrillon Stéphanie
Published: March 2024

Ocean fine-scale dynamics such as submesoscale processes constitute one of the key points in understanding current velocities with a tridimensional approach. Their in situ observation remains challenging due to their short space and time extent and duration. The Northern Current in the Western Mediterranean Sea, corresponding to the Northern branch of the basin cyclonic circulation, can be influenced by wind events, inducing intrusions on the continental shelf and associated fine-scale dynamics. In order to detect these phenomena, the JULIO mooring (JUdicious Location for Intrusion Observation) located on the Eastern side of the Gulf of Lion’s shelf on the 100m isobath, measures tridimensional current velocities since 2012 using an acoustic Doppler current profiler (ADCP) at 300kHz. In addition, vertical velocities have been episodically measured with other methods such as the FreeFall-ADCP (FF-ADCP), and an autonomous Vertical Velocity Profiler (VVP) both developed at MIO. First, the JULIO time-series has shown a significant contribution of biology to vertical motions, with systematic negative vertical velocities measured at night time. This effect was particularly strong in the subsurface layer at 15 to 25 meters depth and enhanced during spring. Second, strong observed 3D-currents, coinciding with wind events, induce current shears and intrusions as well as vertical velocities in this dynamical coastal region with complex bathymetric constraints. Furthermore, the SWOT satellite mission launched in 2022 constitutes a powerful ally by providing a new tool to detect fine-scale features from the surface dynamics near JULIO, and especially during the daily fast sampling phase from April to July 2023. Given the impact of wind forcing on current dynamics in this region, the question arises to what extent the Northern Current and its intrusions on the continental shelf might be affected by climate change.
Present-day ocean simulations of the circumpolar Antarctic
Authors: Rogalla Birgit , Naughten Kaitlin , Holland Paul , Mathiot Pierre , Jourdain Nicolas , Kittel Christoph
Published: March 2024

The West Antarctic Ice Sheet (WAIS) is rapidly losing mass due to ocean-driven melt of its ice shelves, contributing to sea level rise. This melt is associated with the intrusion of circumpolar deep water onto the continental shelf which is impacted by winds, the Amundsen undercurrent, thermodynamic processes, and buoyancy forcing. To study the sensitivity of melt to changes in these components, model configurations need to represent key processes while reducing computational cost to allow for large ensemble simulations. Regional ocean simulations have proven useful in this context, however, configurations that allow interactions between Antarctic regions would be beneficial. We will present results from present-day ocean simulations with a  ¼° circumpolar Antarctic NEMO configuration including sea ice, icebergs, and ice shelf cavities, and up-to-date forcing and bathymetry datasets. We will also discuss challenges associated with open boundary conditions and sensitivity to different forcing datasets. This configuration will provide a platform for attribution studies of ocean-driven melt of the WAIS, ocean projections, and form the starting point for coupled ocean-ice sheet simulations. 
Gravitational field recovery via inter-satellite redshift measurements
Authors: Hackstein Jan Patrick , Philipp Dennis , Hackmann Eva
Published: March 2024

Satellite gravimetry is a common tool to monitor global changes in the Earth system, generally utilising accelerometers aboard satellites to measure acting forces along the orbits. In contrast, high-precision atomic clocks are used in first experiments in terrestrial gravimetry to measure physical heights. In relativistic gravity, a comparison of two clocks is sensitive to their relative positions and velocity, making clocks ideal tools to investigate Earth’s gravity field. However, one important obstacle for Earth-satellite chronometry is the low measurement accuracy of satellite velocities, which enter into the redshift via the Doppler effect.We present an alternative approach based on the framework of general relativity without velocity measurements from ground stations, instead measuring redshift between satellite pairs equipped with clocks via laser ranging. This method promises higher accuracy for gravity field recovery by improving control of the Doppler effect. We investigate this problem in analytically given spacetimes as well as in the general first post-Newtonian approximation of Earth’s gravity field, and discuss the prospects for gravity field recovery.