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The oxidation state of sulfur in slab fluids is controversial, with both dominantly oxidized and reduced species proposed. Here we use in situ X-ray absorption spectroscopy analysis of sulfur-in-apatite to monitor changes in the oxidation state of sulfur during high-P metasomatism by slab fluids in the subduction channel. Our samples include a 73 cm continuous transect of reaction zones between a metagabbroic eclogite block and serpentinite matrix from a mélange zone on the island of Syros, Greece. The block core consists of garnet, omphacite, phengite, paragonite, epidote-clinozoisite, and rutile. In this region, apatite is only observed as elongate inclusions in omphacite cores. From the core outwards micas are increasingly replaced by epidote-clinozoisite, garnets are smaller and more frequent, pyrite + bornite is observed as inclusions in recrystallized omphacite, and apatite is increasingly abundant in the matrix and inclusions in garnet. A major transition at 48 cm separates an assemblage of Ca-Na amphibole, omphacite, chlorite, pyrite, and apatite from the inner garnet-bearing eclogite assemblages. Omphacite disappears from the assemblage at ~56 cm and amphibole compositions sharply transition to tremolite at 59 cm. Finally, the assemblage tremolite + talc + pyrite is observed after ~70 cm.Apatites in the eclogite assemblages exclusively display S6+ peaks in their absorption spectra. This includes apatite inclusions in omphacite in the least altered lithology, as well as matrix apatite and isolated apatite inclusions in garnet in the outermost metasomatized eclogite zone. In the intermediate pyrite-rich (~1-5 vol %) amphibole + omphacite + chlorite zone, apatite displays a strong S1- absorption peak in most grains, with rare analyses showing mixed S1- and S6+. Finally, apatite in the outermost tremolite-bearing assemblages only displays a S6+ peak. The pyrite-rich zone at 48 cm occurs at the initial interface between the serpentinite matrix and eclogite block

Garnet xenocrysts from kimberlites provide unique insights into the composition, structure and evolution of the subcontinental lithospheric mantle (SCLM). For example, different metasomatic events in the SCLM are reflected in compositional differences between garnet xenocrysts. As mantle metasomatism largely controls the physical and chemical properties of the SCLM, it exerts first order control over the genesis of kimberlitic magmas and diamond formation. However, dating mantle lithologies and processes is complicated by high ambient temperatures that allow the equilibration of most isotopic systems up to the time of kimberlite eruption. As a consequence, the temporal connection between metasomatic events in the mantle and kimberlite genesis is commonly ambiguous. In this study, we applied LA-ICPMS U-Pb dating to 43 harzburgitic, lherzolithic and megacrystic garnet xenocrysts from the ~376 Ma diamondiferous V. Grib kimberlite, Russia, in order to investigate the link between different types of mantle metasomatism and kimberlite genesis. Our results indicate that, with two possible exceptions, only harzburgitic garnet overlaps in age with the kimberlite eruption, whereas lherzolitic and megacrystic garnet crystals are ~20 to 130 million years older. Furthermore, garnet U-Pb ages and Ni-in-garnet temperatures of ~820 to 1200 °C do not correlate. This, and the high closure temperature of U-Pb in garnet (≥900 °C) suggests that the garnet U-Pb ages indeed reflect metasomatic events in the SCLM. However, the U-Pb ages could also reflect cooling ages. In this case, the metasomatic events recorded in the garnet crystals must still have occurred up to ~130 million years prior to the eruption of the V. Grib kimberlite. These findings have far-reaching implications for the genesis of (diamondiferous) kimberlites, as they clearly show that the time lag between metasomatic events in the SCLM, as recorded in kimberlitic garnet xenocrysts, and kimberlite eruption may extend to te

The 11th Galileo Conference of the European Geosciences Union (EGU) focused on "Solid Earth and Geohazards in the Exascale Era." This abstract presents the main outcomes and conclusions from the conference breakout sessions, which aimed to provide recommendations for the future of solid earth research. The discussions highlighted the challenges and opportunities associated with high-performance computing (HPC) in solid earth sciences. The key findings include the need for collaboration between computer scientists and solid earth domain-specific scientists, the importance of portability software layers for different hardware architectures, the adoption of programming models for easier development and deployment of applications, the necessity of HPC training at all career stages, the improvement of accessibility and authentication mechanisms for European machines, and the readiness of urgent computing services for natural catastrophes. The conference also emphasized the significance of sustainable funding, software engineering best practices, and the development of modular and interoperable codes and workflows. Overall, the conference provided insights into the current status of computational solid earth research and offered recommendations for future advancements in the field.

The Infrared Atmospheric Sounding Interferometer (IASI), flying on board the suite of Metop satellites for more than 15 years, has shown an excellent stability over its entire lifespan and a very good consistency between the three instruments (on board Metop-A, -B and -C). This makes the IASI dataset an excellent climate data record. For the detection and the characterization of clouds, the current IASI operational Level 2 product is highly performant. However, since it was first released in 2007, the L2 cloud data have undergone a series of updates which have not yet been reprocessed back in time. This leads to discontinuities in the data record which makes it very difficult for use in long-term studies. Even in the event of a complete reprocessing of the L2, there would also be no guarantee on the homogeneity of the futures versions. Other cloud products exist (e.g. the AVHRR-L1C, the cloud_cci, the CIRS-LMD) but those are usually either less accurate or sensitive to cloud detection or are not available in near-real-time. These limitations in the existing products triggered the development of a sensitive and coherent IASI cloud detection dataset. Here we present a new cloud detection algorithm for the IASI measurements based on a Neural Network (NN). The input data consists of a set of 45 IASI channels. Those were selected outside the regions affected by CO2, CFC-11 and CFC-12 absorptions to avoid any long-term bias in the detection as their concentrations are evolving over time in the atmosphere. As a reference dataset, we use the current version (v6.6) of the IASI L2 cloud product. The IASI-derived NN cloud product appears to be both accurate in the cloud detection and coherent over the whole IASI period and between the three versions of the instrument. To illustrate this, we show global distributions and time series of the cloud fractions and we assess the quality of the cloud mask by comparing the NN product against several other cloud products. We also evalua, info:eu-repo/semantics/nonPublished

The spatial and temporal variability of extreme wave climate in the North Atlantic Ocean and the Mediterranean Sea is assessed using a 31-year wave model hindcast. Seasonality accounts for 50% of the extreme wave height variability in the North Atlantic Ocean and up to 70% in some areas of the Mediterranean Sea. Once seasonality is filtered out, the North Atlantic Oscillation and the Scandinavian index are the dominant large-scale atmospheric patterns that control the interannual variability of extreme waves during winters in the North Atlantic Ocean; to a lesser extent, the East Atlantic Oscillation also modulates extreme waves in the central part of the basin. In the Mediterranean Sea, the dominant modes are the East Atlantic and East Atlantic-Western Russia modes, which act strongly during their negative phases. A new methodology for analyzing the atmospheric signature associated with extreme waves is proposed. The method obtains the composites of significant wave height (SWH), mean sea level pressure (MSLP), and 10m height wind velocity (U 10) using the instant when specific climatic indices have a stronger correlation with extreme waves.

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[EN] Although often neglected, model validation is a key topic in flood risk analysis, as flood risk estimates are used to underpin large investments and important decisions. In this paper, we discuss the state of the art of flood risk model validation, using as input the discussion among more than 50 experts at two scientific workshop events. The events aimed at identifying policy and research recommendations towards promoting more common practice of validation, and an improvement of flood risk model reliability. We pay specific attention to different components of the risk modelling chain (i.e. flood hazard, defence failure, and flood damage analysis) as well as to their role in risk estimates, to highlight specificities and commonalities with respect to implemented techniques and research needs. The main conclusions from this analysis can be summarised as the need of higher quality data to perform validation and of benchmark solutions to be followed in different contexts, along with a greater involvement of end-users in the application on flood risk model validation.

Drought events are of great importance in most Mediterranean climate regions because of the diverse and costly impacts they have in various economic sectors and on the environment. The effects of this natural hazard on rainfed crops are particularly evident. In this study the impacts of drought on two representative rainfed crops in Spain (wheat and barley) were assessed. As the agriculture sector is vulnerable to climate, it is especially important to identify the most appropriate tools for monitoring the impact of the weather on crops, and particularly the impact of drought. Drought indices are the most effective tool for that purpose. Various drought indices have been used to assess the influence of drought on crop yields in Spain, including the Standardized Precipitation Evapotranspiration Index (SPEI), the Standardized Precipitation Index (SPI), the Palmer drought indices (Palmer Drought Severity Index, PDSI; Palmer Z Index, Z Index; Palmer Hydrological Drought Index, PHDI; Palmer Modified Drought Index, PMDI), and the Standardized Palmer Drought Index (SPDI). Two sets of crop yield data at different spatial scales and temporal periods were used in the analysis. The results showed that drought indices calculated at different timescales (SPI, SPEI) most closely correlated with crop yield. The results also suggested that different patterns of yield response to drought occurred depending on the region, period of the year, and the drought timescale. The differing responses across the country were related to season and the magnitude of various climate variables.

Numerical simulation of inundation processes and subsequent drying of floodplains is a challenging issue for hydrodynamic models. In particular, classical approaches are designed for explicit schemes, hence they are time- consuming and prevent fully implicit time integration. In this work, a new wetting – drying algorithm with implicit time-stepping is developed based on piecewise linear Runge - Kutta discontinuous Galerkin approximations for the shallow water equations. The principle of this algorithm is to set a limitation for the fluid depth and a blending parameter in order to ensure local mass conservation and rapid transition of a wet - dry interface. This scheme is integrated into the Second-generation Louvain-la-Neuve Ice-ocean Model (SLIM). The method is first validated by means of the analytical Thacker test case, showing its well-balancing property. Then, it is applied to the Tonle Sap Lake in the Cambodia floodplain, an integral component of the Mekong River Basin. This lake plays an important role in livelihoods of the Southeast Asian riparian residents and has a unique flow feature: it constitutes a storage area for flows coming from the Mekong River during the flooding seasons and then, during the dry seasons, it provides water to the Mekong delta. As a consequence, the Tonle Sap Lake experiences significant water level fluctuations during a year, with large variations of the total flooded area. The simulation results are investigated for two distinct flow seasons, pointing to the well-foundedness of the new wetting-drying scheme.

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Vertical discretisation is crucial in the modelling of lake thermocline oscillations. For finite element methods, a simple way to increase the resolution close to the oscillating thermocline is to use vertical adaptive coordinates. With an Arbitrary Lagrangian-Eulerian (ALE) formulation, the mesh can be adapted to increase the resolution in regions with strong shear or stratification. In such an application, consistency and conservativity must be strictly enforced. SLIM 3D, a discontinuous-Galerkin finite element model for shallow-water flows (www.climate.be/slim, e.g. Kärnä et al., 2013, Delandmeter et al., 2015), was designed to be strictly consistent and conservative in its discrete formulation. In this context, special care must be paid to the coupling of the external and internal modes of the model and the moving mesh algorithm. In this framework, the mesh can be adapted arbitrarily in the vertical direction. Two moving mesh algorithms were implemented: the first one computes an a-priori optimal mesh; the second one diffuses vertically the mesh (Burchard et al., 2004, Hofmeister et al., 2010). The criteria used to define the optimal mesh and the diffusion function are related to a suitable measure of shear and stratification. We will present in detail the design of the model and how the consistency and conservativity is obtained. Then we will apply it to both idealised benchmarks and the wind-forced thermocline oscillations in Lake Tanganyika (Naithani et al. 2002).

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Electrical resistivity methods have been widely used for the last 40 years in many fields: groundwater investigation, soil and water pollution, engineering application for subsurface surveys, etc. Many factors can influence the electrical resistivity of a media, and thus influence the ERT measurements. Among those factors, it is known that plant roots affect bulk electrical resistivity. However, this impact is not yet well understood.

In dynamic root architecture models, root growth is represented by moving root tips whose line trajectory results in the creation of new root segments. Typically, the direction of root growth is calculated as the vector sum of various direction-affecting components. However, in our simulations this did not reproduce experimental observations of root growth in structured soil.

Water uptake is crucial for plant productivity. Trait based breeding for more water efficient crops will enable a sustainable agricultural management under specific pedoclimatic conditions, and can increase drought resistance of plants. Mathematical modelling can be used to find suitable root system traits for better water uptake efficiency defined as amount of water taken up per unit of root biomass. This approach requires large simulation times and large number of simulation runs, since we test different root systems under different pedoclimatic conditions.

How is root water uptake distributed along the root system and what root properties control this distribution? Here we present a method to: 1) measure root water uptake and 2) inversely estimate the root hydraulic conductivities.

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Fine-grained sediment is perhaps the most widespread and pervasive contaminant in aquatic systems reflecting its role in influencing the quality of the water (e.g., turbidity, vector of chemicals and other pollutants) and its detrimental effect on infrastructure (e.g., dams, turbines) and aquatic habitats (e.g., salmonid spawning grounds) through sedimentation. Determining the sources of fine-grained sediment thus represents an important requirement for watershed and coastal management, as well as for understanding the evolution of landscapes and ocean basins. Sediment source fingerprinting utilizes the diagnostic physical, chemical and biological properties (i.e., tracers) of source materials to enable samples of collected sediment to be apportioned to these sources. This review examines the development of the technique within the earth and ocean sciences, focusing mainly on agricultural landscapes. However, the development of new tracers, such as compound-specific stable isotopes, has allowed the technique to be applied in a growing number of environmental settings including forested (including wildfire-impacted forests), urban and estuarine/coastal settings. This review also describes other applications of the fingerprinting approach such as geoarchaeological (e.g., archaeological site formation), forensic (e.g., identifying the sources of soil/sediment particles in criminal investigations) and human health (e.g., identifying the sources of airborne particulate matter, PM2.5) applications. Identifying commonalities in methods and approaches between environments and disciplines should foster collaboration and the exchange of ideas. Furthermore, refinement of the sediment source fingerprinting technique requires that several methodological issues be addressed. These methodological issues range from the initial sampling design to the interpretation of the final apportionment results. This review also identifies and assesses these methodological concerns.

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Root water uptake is a main process in the hydrological cycle and vital for water management in agronomy. In most models of root water uptake, the spatial and temporal soil water status and plant root distributions are required for water flow simulations. However, dynamic root growth and root distributions are not easy and time consuming to measure by normal approaches. Furthermore, root water uptake cannot be measured directly in the field. Therefore, it is necessary to incorporate monitoring data of soil water content and potential and root distributions within a modeling framework to explore the interaction between soil water availability and root water uptake.

For many years, the rhizosphere, which is the zone of soil in the vicinity of the roots and which is influenced by the roots, is known as a unique soil environment with different physical, biological and chemical properties than those of the bulk soil. Indeed, in recent studies it has been shown that root exudate and especially mucilage alter the hydraulic properties of the soil, and that drying and wetting cycles of mucilage result in non-equilibrium water dynamics in the rhizosphere. While there are experimental evidences and simplified 1D model for those concepts, an integrated model that considers rhizosphere processes with a detailed model for water and roots flow is absent. Therefore, the objective of this work is to develop a 3D physical model of water flow in the soil-plant continuum that take in consideration root architecture and rhizosphere specific properties. Ultimately, this model will enhance our understanding on the impact of processes occurring in the rhizosphere on water flow and root water uptake.

The Flood Directive 2007/60/CE establishes a common framework within the European Union for assessing and reducing risks posed by floods on human health, the environment, economic activity and cultural heritage. For that purpose, Member States had to establish flood areas and flood risk maps, and subsequently, flood risk management plans (due December 2015). According to the Directive, special attention is to be paid to international coordination for transboundary water courses, integrated management approaches at the catchment scale, cost-effectiveness of measures and public involvement. Management measures must focus on reducing the probability of flooding and the potential consequences of flooding. They must cover prevention, protection and preparedness and must take into account relevant aspects, such as water management, soil management, spatial planning, land use and nature conservation. Floods in Wallonia mostly originate from overflowing of both little sloped rivers and highly reactive rivers but also, from concentrated runoff in the intensely cultivated and erosion-prone region north of the Sambre- Meuse axis. Consequently, walloon flood area maps not only show flood areas based on hydraulic modelling and observations but also runoff concentration axis in agricultural areas. Now released to the public, this information can be used to assess the risk of damage for land planning and erosion control strategies. Incidentally, some 166 km2 were mapped as flood hazard area with a return period of 25 years, 28.8 of which are urbanized or destined to urbanisation and counting of number of approximatively 39.000 people living in those areas. Flood area and flood risk maps should be the starting point of elaborating flood risk management plans.

Accurate knowledge of the shallow soil properties is of prime importance in agricultural, hydrological and environmental engineering. During the last decade, numerous geophysical techniques, either invasive or resorting to proximal or remote sensing, have been developed and applied for quantitative characterization of soil properties. Amongst them, time domain reflectrometry (TDR) and frequency domain reflectometry (FDR) are recognized as standard techniques for the determination of soil dielectric permittivity and electrical conductivity, based on the reflected electromagnetic waves from a probe inserted into the soil.

Decomposing litter accumulated at the soil surface in forest ecosystems play a major role in a series of ecosystem processes (soil carbon sequestration, nutrient release through decomposition, water retention, buffering of soil temperature variations, tree regeneration, population dynamics of ground vegetation and soil fauna, ...). Besides, the presence of litter is acknowledged to influence remote sensing radar data over forested areas and accurate quantification of litter radiative properties is essential for proper processing of these data. In these respects, ground-penetrating radar (GPR) presents particular interests, potentially allowing for fast and non-invasive characterization of organic layers with fine spatial and/or temporal resolutions as well as for providing detailed information on litter electrical properties which are required for modeling either active or passive microwave remote sensing data.

Stomata can close to regulate plant water loss under unfavourable water availability. This closure can be triggered by hydraulic (‘H’) and/or chemical signals (‘C’, ‘H+C’). By combining plant hydraulic relations with a model for stomatal conductance, including chemical signalling, our aim was to derive a simple relation that links soil water availability, expressed as the fraction of roots in dry soil, to transpiration.

In this study we started from local hydraulic analysis of idealized root systems to develop a mathematical framework necessary for the understanding of global root systems behaviors. The underlying assumption of this study was that the plant is naturally optimised for the water uptake. The root system is thus a pipe network dedicated to the capture and transport of water. The main objective of the present research is to explain the fitness of major types of root architectures to their environment.

Roots change their surrounding soil chemically, physically and biologically. This includes changes in soil moisture and solute concentration, the exudation of organic substances into the rhizosphere, increased growth of soil microorganisms, or changes in soil structure. The fate of water and solutes in the root zone is highly determined by these root-soil interactions. Mathematical models of soil root systems in combination with non-invasive techniques able to characterize root systems are a promising tool to understand and predict the behaviour of water and solutes in the root zone. With respect to different fields of applications, predictive mathematical models can contribute to the solution of optimal control problems in plant recourse efficiency. This may result in significant gains in productivity, efficiency and environmental sustainability in various land use activities.

To overcome dry spells, plant roots can use macroscopic structures in the soil to reach deeper water reservoirs. We used R-SWMS, an explicit soil- and root water uptake model and integrated different kinds of macropores within the soil domain. Root growth is based on vector addition and influenced by the local soil parameters, e.g. penetrometer resistance or nutrient availability, around a growing root tip. Root water uptake from the macroporebulk soil interface was simulated with respect to the contact area between roots and bulk soil. The macropore was assumed to be air-filled.

Water and nutrient transfer to plant roots is determined by processes occurring from the single root to the entire root system. A mechanistic spatially distributed description of these processes would require a sub mm discretization which is computationally not feasible. In this contribution, we present efficient solution techniques to represent accurate nutrient uptake by plant roots.

This work aims at presenting the scientific results stemming from six Short-Term Scientific Missions (STSMs) funded by the COST (European COoperation in Science and Technology) Action TU1208 “Civil Engineering Applications of Ground Penetrating Radar” (Action Chair: Lara Pajewski, STSM Manager: Marian Marciniak). STSMs are important means to develop linkages and scientific collaborations between participating institutions involved in a COST Action. Scientists have the possibility to go to an institution abroad, in order to undertake joint research and share techniques/equipment/infrastructures that may not be available in their own institution. STSMs are particularly intended for Early Stage Researchers (ESRs), i.e., young scientists who obtained their PhD since no more than 8 years when they started to be involved in the Action. Duration of a standard STSM can be from 5 to 90 days and the research activities carried out during this short stay shall specifically contribute to the achievement of the scientific objectives of the supporting COST Action.

In this study, we developed a new operation pipe showing that the combined use of computer models and in vivo experiments allows one a better analysis of the water fluxes in the soil-plant system and can help researchers to decrypt the root water uptake dynamics. From an experimental point of view, we monitored in 2D the evolution of soil water content around roots of transpiring maize plants using a light transmission imaging (LTI) technique on a rhizotron. Subsequently, we digitized the entire root system in order to create an input file for the model RSWMS (HYDRUS-like model for soil-plant water transfers). In the other hand, we performed a global sensitivity analysis of the modeled experiment to highlight the plant parameters that can be measured thanks to such a procedure. Then fitting the simulated changes of distributed Sink term in Richards equation to experimental data enabled us to depict the local radial and axial conductivities.

Besides being the largest natural satellite known in the Solar System, Ganymede most likely also has the most differentiated internal structure of all satellites.Ganymede is thought to have an external water/ice layer subdivided into three sublayers: an outer ice shell, a global liquid water ocean, and a high pressure ice mantle. The presence of a water layer is supported by the possible detection of an induced magnetic field with the Galileo spacecraft. The metallic core is divided into a solid (inner core) and a liquid (outer core) part. Between the water/ice and the metallic layers, a rock mantle is expected. The JUpiter ICy moons Explorer (JUICE) mission led by ESA is planned to be launched in 2022. The spacecraft is expected to enter in orbit around Ganymede in september 2032. The Ganymede Tour will alternate elliptic and circular phases at different altitudes. The circular phases at altitudes of a few hundred kilometers are dedicated partly to the study of the internal structure such as the determination of the extent and composition of the ocean and of the surface ice shell. The payload of the spacecraft comprises the radio science package 3GM (Gravity and Geophysics of Jupiter and the Galilean Moons) that will be used to measure the Doppler effect on radio links between the orbiter and the Earth which will be affected by the gravity field of Ganymede. The gravity field of Ganymede is the sum of the static hydrostatic field (related to the secular Love number kf ),of the periodically varying field due to tidal deformations (related to the tidal Love number k2 and the tidal dissipation factor Q ), of the periodically varying field due to change in the rotation state (variations in the rotation rate and in the orientation of the rotation axis), and of the non-hydrostatic field that may be due to mass anomalies. The tidal and rotation parameters depend on the internal structure of the satellite (density, size, rheological properties of the different layers) in a

The quasi two-day wave (QTDW) at 82–97km altitude over Collm (51° N, 13° E) has been observed using a VHF meteor radar. The long-term mean amplitudes calculated using data between September 2004 and August 2014 show a strong summer maximum 5 and a much weaker winter maximum. In summer, the meridional amplitude is slightly larger than the zonal one with about 15ms°1 at 91 km height. Phase differences are slightly greater than 90° on an average. The periods of the summer QTDW vary between 43 and 52H during strong bursts, while in winter the periods tend to be more diffuse. On an average, the summer QTDW is amplified after a maximum of 10 zonal wind shear which is connected with the summer mesospheric jet and there is a possible correlation of the summer mean amplitudes with the backgound wind shear. QTDW amplitudes exhibit considerable inter-annual variability, however, a clear relation between the 11 year solar cycle and the QTDW is not found.

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