bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysing the compaction of crushed salt in repositories for high-level waste in salt formations using a dedicated constitutive model
Authors: Simo Eric , Helfer Thomas , Nagel Thomas , Paola Rocio León Vargas
Published: March 2022

The isolation of radioactive waste in a high-level waste (HLW) repository in salt formations is provided by a multi-barrier system based on a combination of engineered and natural barriers. The natural barrier is provided by salt rock itself, whereas the engineered barrier is comprised of sealing components installed at specific locations in the repository. In this concept, the long-term safety of the mined excavations will be ensured by backfilling with crushed salt. Crushed salt acquires its sealing capacity through compaction due to the convergence of the rock. Convergence increases by the heat produced by the disposed waste and by humidity in the repository and the water content in the rock. After several thousands of years, it is expected that crushed salt will reach the same mechanical and hydraulic properties as the intact salt host rock. In the scope of the R&D project RANGERS aiming at developing a methodology for design and performance assessment of geotechnical barriers in a HLW repository in salt formations, a constitutive model for crushed salt developed by Hein (1991) and modified by Breiderich (1994) has been implemented in the FE-code OpenGeoSys through the code generator MFront. The model has been subsequently applied to model the compaction of crushed salt in disposal drifts in the repository mine and thus helping to determine when the crushed salt will gain its function as long term sealing of the HLW-repository. 

 

Hein, H. J.: "Ein Stoffgesetz zur Beschreibung des lhermomechanischen Verhaltens von Steinsolzgranulat", Dissertation RWTH Aachen, 1991.

Breiderich, H. J.: " Gekoppelte Berechnung der thermomechanischen FeldgroBen in einer Steinsalzformation infolge der Einlagerung radioaktiver warmefreisetzender Abfälle", Dissertation RWTH Aachen, 1994
Multidecadal Modulations of Tropical Atlantic impact on ENSO
Authors: Rodriguez-Fonseca Belen , Polo Sanchez Irene , Mohino Harris Elsa , Losada Doval Teresa , Martin del Rey Marta , Keenlyside Noel , Mechoso Carlos Roberto
Published: March 2022

Observational studies have reported that tropical Atlantic interannual variability impacts
on ENSO in different seasons and periods: Atlantic Ni ̃nos (AN) in boreal summer during
negative phases of the Atlantic Multidecadal Variability (AMV); and tropical north Atlantic
(TNA) in boreal spring during positive AMV. Nevertheless, this relation is not clear for the
whole observational record. This paper is an step forward towards understanding of tropical
Atlantic impacts on ENSO: how and when do they occur? Using observations and a pool of
preindustrial control simulations from the CMIP5 initiative we investigate the background
ocean and atmospheric conditions promoting these tropical interbasin connections.Periods
with a negative AN-ENSO connection appear characterized by a shallower thermocline
over the western Pacific and deeper in the east, together with an increase in interannual
SST variability over the tropics. Periods with a negative TNA-ENSO connection appear
characterized by a steeper thermocline in the Pacific and positive interhemispheric SST
gradient in the the Atlantic. A decrease in tropical Pacific atmospheric and ocean variability
characterizes these periods.
Slope Stability Assessment of Rock Slopes Using Finite Element Modelling Along National Highway-5, Shimla, Northwestern Himalaya, India
Authors: Singh Jugraj , Thakur Mahesh , Kishore Naval
Published: March 2022

Technology advances and rising population has led to the establishment of geoengineering projects such as dams, tunnels, bridges, road network, etc. in the mountainous terrain which causes slope destabilization. National Highway-5 connects Shimla, Kinnaur, Kullu, and China border to the rest of the country. The route is of paramount importance for defense and security purposes. The area encompasses complex geomorphological and geological terrain and often encounters road cut slopes susceptible to failure. In the present study, a detailed geotechnical investigation is carried out around Dhalli Landslide (September, 2017) and Malyana Landslide (August, 2018) along NH-5, Shimla, Himachal Pradesh. RMR, SMR, kinematic analysis and numerical modeling using the finite element modelling (FEM) technique is applied for the aforementioned two slopes and its nearby area. Kinematic analysis of joint data shows that rocks are prone to mainly wedge and planar failures. The RMR results show that the slopes belong to fair (Class III) and weak (Class IV) category. The SMR results for the slopes show that slopes lie in the completely unstable (Class V) category, unstable (Class IV) category and in the partially stable (Class III) category. The Strength Reduction Factor (SRF) was calculated using RS2 module of Rocscience. The SRF for both the slopes was less than 1 which shows that the slopes are completely unstable. Dominating factors responsible for the slope instability are identified and accordingly, some suggestions are proposed to strengthen the stability of road cut slope.

 
The AMMA-CATCH observatory : a platform to address scientific and societal issues in West-Africa
Authors: Cohard Jean-Martial , Grippa Manuela , Lawin Emmanuel , Peugeot Christophe , Assanou Bil , Boucher Marie , Chaffard Véronique , Diawara Mamadou , Etchanchu Jordi , Faye Gayane , Galle Sylvie , Mainassara Ibrahim , Malam-Abdou Moussa , Mamadou Ossenatou , Mariscal Armand , Mougin Eric , Moumouni Soumaïla , Panthou Geremy , Lebel Thierry
Published: March 2022

West Africa is undergoing a drastic transition in climate, demography and land use. This has a strong impact on the development capacities of every country in the region. While regional trends in each of these three key areas are relatively well known, decision makers scientists are often lacking a proper vision of how climate and land use are evolving at spatial and temporal scales that count most for the living of populations. Moreover, the hydrological implications of these climate and land use evolutions are hardly documented, while models have still difficulties in reproducing them. It is therefore of utmost importance to rely on combined observation-modeling strategies to better apprehend the ongoing transition and explore possible future trajectories in terms of water resources, hydrological risks and food security. To that end, the regional long-term observatory AMMA-CATCH aims at monitoring the impacts of global changes on the continental water cycle and the functioning of the critical zone in West Africa, through a combination of mesoscale observations, data analyses and local to regional modeling. Three main issues are currently guiding our observation strategy: (1) Multi-decadal trends of hydro-climatic hazards (past, current and projected); (2) Dynamics of vegetation, land use and their interactions with the water cycle; (3) Trajectories of water resources. This strategy is supported by metrology, technology watch and innovation. The AMMA-CATCH observatory has been collecting data since 1990 on four highly instrumented sites (each of the roughly covering 10000 to 20000 km²), staggered from North to South of West Africa, in order to measure the latitudinal gradient in different eco-climatic zones (Benin, Niger, Mali), and since 2016, from complementary sites in Senegal and Niger, to assess the longitudinal variability in the Sahelian area. It is part of the OZCAR French Critical Zone observatory network and supported by French research institutions with long term engagement.

This presentation aims at highlighting recent results obtained by analyzing the data of the AMMA-CATCH observatory covering a large range of hydrology/land use related issues, such as tipping points in hydrology, rainfall intensification, infrastructure design norms, soil restoration, local and regional hyper-resolution hydrological modeling, …. This presentation also aims at encouraging a African-European structuration of socio-hydro-climate observations in this region in order to provide a strong science-based foundation for the elaboration of adaptation policies.
Digital Twin of the Ocean - An Introduction to the ILIAD project
Authors: Bye Bente Lilja , Sylaios Georgios , Berre Arne-Jørgen , Van Dam Simon , Kiousi Vivian
Published: March 2022

The ILIAD Digital Twin of the Ocean, a H2020 funded project, builds on the assets resulting from two decades of investments in policies and infrastructures for the blue economy and aims at establishing an interoperable, data-intensive, and cost-effective Digital Twin of the Ocean. It capitalizes on the explosion of new data provided by many different Earth observation sources, advanced computing infrastructures (cloud computing, HPC, Internet of Things, Big Data, social networking, and more) in an inclusive, virtual/augmented, and engaging fashion to address all Earth data challenges. It will contribute towards a sustainable ocean economy as defined by the Centre for the Fourth Industrial Revolution and the Ocean, a hub for global, multistakeholder co-operation.
The ILIAD Digital Twin of the Ocean will fuse a large volume of diverse data, in a semantically rich and data agnostic approach to enable simultaneous communication with real world systems and models. Ontologies and a standard style-layered descriptor will facilitate semantic information and intuitive discovery of underlying information and knowledge to provide a seamless experience. The combination of geovisualisation, immersive visualization and virtual or augmented reality allows users to explore, synthesize, present, and analyze the underlying geospatial data in an interactive manner. To realize its potential, the ILIAD Digital Twin of the Ocean will follow the System of Systems approach, integrating the plethora of existing EU Earth Observing and Modelling Digital Infrastructures and Facilities. To promote additional applications through ILIAD Digital Twin of the Ocean, the partners will create the ILIAD Marketplace, included a market for Geosciences related applications and services. Like an app store, providers will use the ILIAD Marketplace to distribute apps, plug-ins, interfaces, raw data, citizen science data, synthesized information, and value-adding services derived from the ILIAD Digital Twin of the Ocean. It will also be an efficient way for scientists to discover and find relevant applications and services.
Unprecedented observations of Medicane precipitation structure from the GPM Core Observatory
Authors: D'Adderio Leo Pio , Casella Daniele , Dietrich Stefano , Sanò Paolo , Panegrossi Giulia
Published: March 2022

Mediterranean hurricanes (Medicanes) are meso-scale cyclones typical of the Mediterranean area which during their lifetime may some some dynamical features with tropical cyclones: the presence of a quasi-cloud-free calm eye, spiral-like cloud bands elongated from the center, strong winds close to the vortex center and a deep warm core. They are often associated to heavy rainfall and flooding, intense wind, and high waves and storm surge, and can be serious threats to human life and infrastructure. Recent studies highlighted that extra-tropical and tropical-like cyclone characteristics can alternate or even coexist in the same cyclonic system, and that only in some cases strong diabatic forcing leads to tropical-like transition (i.e., purely barotropic structure). In this study the satellite measurements from the NASA/JAXA Global Precipitation Measurement Core Observatory (GPM-CO) active and passive microwave (MW) sensors are used to analyze the precipitation structure of the most intense Mediterranean Hurricane (Medicane) on record, named Ianos, which swept across the Ionian Sea between 14 and 18 September 2020. Two GPM-CO overpasses, available during Ianos development and tropical-like cyclone (mature) phase, are analyzed in detail. GPM Microwave Imager (GMI) measurements are used to carry out a comparative analysis of the medicane precipitation structure and microphysics processes between the two phases. The GPM-CO Dual-frequency Precipitation Radar (DPR) overpass, available for the first time during a medicane mature phase, provides key measurements and products to analyze the 3D precipitation structure in the rainbands, offering further evidence of the main precipitation microphysics processes inferred from the passive MW measurement analysis. Substantial difference in the rainband precipitation structure is observed, with deeper convection and stronger updraft features during development then at the mature phase, when also shallow precipitation/warm rain processes are observed in the inner region around the medicane eye. These features play a key role to explain the substantial drop in lightning activity during Ianos mature phase. Graupel-ice electrification process is inhibited due to the combined effect of strong horizontal wind and the observed limited growth of graupel. Starting from the detailed analysis of Ianos, a comparative study among the medicanes occurred during the GPM era is carried out. The goal is to extract common features from PMW measurements characterizing the different stage of medicanes’ evolution. The study demonstrates the value of the GPM-CO not only to characterize medicane precipitation structure and microphysics processes and convection strength with unprecedented detail, but also to provide evidence of tropical-like characteristics and of similarities with tropical cyclones for those medicanes undergoing tropical-like transition during their mature phase.
Barite Precipitation on Suspended Organic Matter in the Ocean Water Column
Authors: Martinez-Ruiz Francisca , Paytan Adina , Gonzalez-Muñoz Maria Teresa , Jroundi Fadwa , Abad Maria del Mar , Lam Phoebe J. , Horner Tristan J. , Kastner Miriam
Published: March 2022

Despite decades of research, barite formation in the ocean water column has been widely discussed since most of the world´s ocean mesopelagic zone, in which barite forms, is generally undersaturated with respect to this mineral. Recent evidence from experimental work and also from observations in microenvironments of intense organic matter mineralization in the ocean support that barite forms via transient amorphous precursor phases that evolve to barite crystals. This crystallization pathway is further supported by the close association of barite particles with extracellular polymeric substances (EPS) at depths of higher bacterial production. Barite particles association with exopolymers demonstrates that microbial processes and exopolymer production play a major role in promoting locally high concentrations of Ba and barite precipitation. Scanning and high-resolution transmission electron microscopy analyses from particulate samples collected using multiple-unit large volume in-situ filtration systems have shown how these amorphous precursor phase nucleate, demonstrating that phosphate groups in EPS and bacterial cells are the sites for binding Ba. EDX maps have shown the nature of these P-rich nanometer-sized amorphous particles that evolve to poorly crystallized barite and to micrometer-sized barite crystals. The strong link between organo-mineralization and microbial processes further supports the role that such processes play in biomineralization in the ocean. The distribution of particulate Ba and Ba isotopes in the water column is also consistent with such precipitation mechanisms. Hence, processes involved in barite precipitation including primary production, export production, organic matter degradation, bacterial respiration, EPS formation, aggregation, and sinking, need to be taken into account when interpreting temporal and spatial variability in the Ba:Corg ratios and barite accumulation in marine sediments.
Metabolic synchrony in stream networks
Authors: Diamond Jacob
Published: March 2022

Synchrony of dissolved oxygen (DO) signals among river network elements reflects the dynamic balance between shared regional drivers, signal propagation, and local hydraulic, energetic, and metabolic heterogeneity. We used high frequency DO measurements at 42 sites across five watersheds catchments to evaluate DO signal synchrony among reaches in response to dynamic variation in light availability and discharge. We hypothesized that homogeneity of light availability and longitudinal hydrologic connectivity between sites would enhance synchrony in DO signals. We observed strong support that increasing spatial homogeneity of light inputs, both in magnitude and diel variation, greatly increase diel DO signal synchrony both within and across stream networks during early spring and fall. We further observed the central role of longitudinal connectivity in controlling within network synchrony. Specifically, shared regional drivers (light, temperature) increase the synchrony in DO signals when flow connectivity was high, whereas fine-scale patch behavior and low synchrony, especially in smaller streams, occurred when connectivity declines. A model including light synchrony and longitudinal connectivity explained 65% of variation in dynamic DO synchrony. We provide a framework for evaluating DO signal synchrony at confluences with implications for broadly understanding solute where network flow elements mix. DO synchrony and network and confluence scales provides an empirical demonstration of the dynamic balance between regional drivers and local patch dynamics modulated by the flow-varying length scales of signal integration.
Ecohydrological responses to a series of dry years at the TERENO Observatory NorthEast Germany
Authors: Blume Theresa , Güntner Andreas , Weiler Markus , Heinrich Ingo
Published: March 2022

Ecohydrological consequences of dry years are difficult to predict. To understand the underlying drivers and responses, extensive monitoring over longer periods of time is a prerequisite. We are here providing an overview of multi-year monitoring of different forest stands in the TERENO Observatory NorthEast Germany. These forest stands include pure oak, beech and pine stands as well as mixed stands and the experimental design also allows the comparison of sites with and without accessibility to groundwater. Monitoring covers a large number of variables with high temporal resolution, such as soil moisture and groundwater dynamics but also sapflow and tree growth. Due to the deep groundwater levels and the high conductivity of the sandy soils, water storage dynamics in the large unsaturated zone and the deeper root zone are of special importance. Soil moisture monitoring therefore extends down to a depth of 2m. We provide an overview of the ecohydrological responses of this forest system to the extreme summer and fall of 2018 as well as the progression in the following years.
Analysis of the development mechanisms of a large-hail storm event, on the Adriatic Sea using an atmosphere-ocean coupled model (COAWST)
Authors: Ferretti Rossella , Mazzarella Vincenzo , Marzano Frank , Miglietta Mario Marcello , Picciotti Errico , Montopoli Mario , Baldini Luca , Vulpiani Gianfranco , Tiesi Alessandro , Mazzà Simone , Ricchi Antonio
Published: March 2022

On the morning of 10 July 2019, an intrusion of relatively cold and dry air, over the Adriatic Sea, through a "bora jet", gave rise to a frontal structure at the ground, which moved rapidly from the Northern to the Southern Adriatic. The intense thermal gradient (together with a high positive sea surface temperature anomaly), the interaction of the jet with the complex topography of Apennines  and the coastal boundary, generated a storm structure that moved parallel to the central Italy coast. In particular, between 8UTC and 12UTC, a supercell developed along the coast to the north of Pescara city (middle Adriatic), producing rainfall that reached 130 mm in 3 hours, and a violent hailstorm (estimated diameter greater than 10 cm). 

In this work, the frontal dynamics and the genesis of the thunderstorm are studied using the numerical system COAWST. Local polarimetric radar observations are also used to check the consistency of the simulations in the mature phase of the supercell. Numerical experiments are performed using a 1 km grid over central Italy, initialized using the ECMWF IFS analysis/forecasts. The sensitivity study investigates the role of the orography, the sea surface temperature (SST) and the coupling between ocean and atmosphere. Orography tests include simulations where the relevant peaks of the Apennine range  (such as Gran Sasso and Picentini) are removed as well as cases where their peaks are modified compared to their real values. In terms of SST, we employ, using an uncoupled approach, the ECMWF SST dataset, the MFS-CMEMS Copernicus dataset at 4 km, 0.01°C Satellite SST, and we investigate the role of the SST anomaly (adding +1°C and +2°C to the real field). The role of the ocean-atmosphere interaction is tested using the COAWST numerical model using an ocean model numerical grid at 1 km resolution over the whole Adriatic Sea. 

The preliminary results show that the topography and in particular  the interaction with the peaks of the Apennine range plays a fundamental role in the dynamics of the cold pool that trigger the convective system. Also, the SST anomaly is found to play an important role in the development of the supercell. In particular, we observed that the simulations forced with MFS-CMEMS SST and the COAWST model runs produce a very realistic SST, in terms of spatial and temporal distribution, but colder by about 1.5 °C in absolute value if compared to observed satellite data. This difference generates lower heat fluxes, less evaporation, weaker precipitations and smaller hail than using warmer SSTs. 
AGU LANDInG (Leadership Academy and Network for Diversity & Inclusion in Geosciences): Reviewing the First Year of AGU’s NSF-Funded Initiative to Promote and Support Equity, Diversity, and Inclusion in the Geosciences
Authors: Fraiser Margaret , Williams Billy , Goodwin Stephanie , Asher Pranoti , Hanson Brooks
Published: March 2022

AGU LANDInG (Leadership Academy and Network for Diversity and Inclusion in the Geosciences) is a multi-faceted project that aims to foster a more inclusive geosciences’ culture by cultivating and elevating DEI (diversity, equity and inclusion) champions within the discipline. Since initiation of NSF funding in late 2020, a DEI Community of Practice (CoP) Network was launched, and the inaugural LANDInG Academy was held. Participation, participant outcomes, and program impact are externally and professionally evaluated.

The LANDInG CoP is an open access, virtual platform providing opportunities for current and aspiring DEI champions to engage in conversation, share resources, build networks, and participate in professional development. A cohort of expert CoP Ambassadors moderates affinity groups created by CoP members and facilitates the CoP’s growth and evolution. The LANDInG CoP is rooted in research indicating that DEI champions and leaders in the geosciences can benefit from a central community for networking and professional development that supports broadening the impact of their efforts.

AGU LANDInG’s DEI Leader Academy commenced at AGU’s Fall Meeting 2021 with a three-day workshop. Workshop programming focused on evidence-based understanding of barriers and solutions to inclusion in geosciences derived from theory, research, and practice. Fellows’ selection and participation in LANDInG Academy was highlighted and promoted at Fall Meeting 2021 to raise their visibility and recognition.

The first year of AGU LANDInG is also marked by the initiation of LANDInG-PRFP, a new LANDInG program for postdoctoral research fellows. LANDInG-PRFP will capitalize on LANDInG’s CoP resources and provide an intentional and impactful DEI professional development experience for cohorts of post-doctoral scholars.
Extreme Weather Impacts on Precipitation-Runoff Processes in Heavily Managed Landscapes
Authors: Aloysius Noel
Published: March 2022

The water and carbon cycles provide vital linkages for maintaining several ecosystem services within the terrestrial landscapes and coastal regions. Yet, the understanding of its spatial and temporal variability as modulated by climate, vegetation and topography, and their impact on downstream coastal zones is limited in heavily managed River Basins. The processes operating within these cycles, such as evapotranspiration and runoff generation, are expected to accelerate as a result of anthropogenic climate change, particularly due to rising temperatures and changing precipitation patterns. A complete knowledge of spatial and temporal variability of the water cycle is essential in order to understand and interpret the causes of change, their impact on vegetation health, runoff and chemical transport to aquatic ecosystems, and to plan for the anticipated changes in the future. In this presentation, we will provide an assessment of the historical changes and variability in weather patterns (temperature and precipitation) and how these changes affected water fluxes and states (evapotranspiration, runoff, and soil moisture) in the Midwestern Region of the Mississippi River Basin in the United States. Our findings will elucidate the need for coordinated efforts that are required to improve the resiliency and sustainability of one the largest and heavily managed River Basins.
Considering Satellite Attitude Quaternions in BeiDou Precise Point Positioning Performance
Authors: Suya Robert Galatiya , Chen Yung-Tsang , Kwong Chiew-Foong , Zhang Penghe
Published: March 2022

The use of theoretical modeling algorithms to compute the satellite altitude causes some errors which are eventually absorbed by the satellite clocks. This adversely reduces the fixed positioning performance in global navigation satellite system (GNSS) precise point positioning (PPP). Currently, different International GNSS service (IGS) analysis centers (ACs) provide satellite altitude quaternions which are an auxiliary dataset necessary in PPP fixed solutions. Hence, this study aims at a comprehensive evaluation of the effect of accounting for the BeiDou satellite attitude quaternions in PPP. The quaternions provided by different ACs are applied to BeiDou PPP using different weighting schemes suitable for handling satellites in three distinct orbits. The obtained numerical results indicate that considering the quaternions in BeiDou PPP reduces the observation residuals, improves the ambiguity fixing, and enhances positioning performance.
The 3-D capability of science and engineering cameras on the ExoMars rover
Authors: Bohacek Eleni
Published: March 2022

The ExoMars Programme will send a rover to Mars in 2022 equipped with a 2 m drill which will search for evidence of extinct life below the surface. This project is focused on the stereo vision systems of the rover, and how better 3-D information can be extracted from the camera images. This is explored through both experimental and simulation-based approaches. The experimental approach was to build a hardware emulator of the three stereo pairs: the Wide-Angle Cameras (WACs) from the Panoramic Camera instrument (PanCam), and the Navigation Camera (NavCam) and Localisation Camera (LocCam) systems. Point clouds were generated from the emulator data and compared against a (LIDAR) generated point cloud to determine which combination of cameras yields the best point clouds. The comparison methods were as follows: the number of tie points, the number of dense cloud points, coordinate extent, surface density, nearest neighbour distance (NND) to the LIDAR cloud, and measurement of a known target. One set of experiments compared the four mast head stereo cameras (WACs and NavCams) and the second set compared all six stereo cameras (WACs, NavCams, and LocCams). The six-view point cloud was the closest match to the LIDAR in terms of mean NND to the LIDAR point cloud, but it was only marginally better than the five-view point clouds and the four-view point cloud made of the WACs and NavCams. The conclusions from both sets of experiments are that the three stereo camera pairs do not contribute equally to improvements in the point clouds generated through photogrammetry. The emulator WACs are the most suited to photogrammetric reconstruction, followed by the emulator NavCams and finally the emulator LocCams.
Integrating energy justice with community climate action planning
Authors: Logan Kathryn G. , Keith Ladd , Gupta Neha , Leinberger Amanda J. , Shelton Rebecca , Jacobs Katharine L.
Published: March 2022

Decarbonisation of energy technologies is essential to meet climate change targets, however, this process has the potential to generate new or further emphasize pre-existing inequalities within society. By ensuring a low carbon energy transition is sustainable and equitable, trade-offs and co-benefits between decarbonisation and other U.S. policy objectives can be achieved. This is important as many communities are in the process of developing or updating their climate action plans (CAPs). The ‘success’ of a CAP is often measured against the greenhouse gas emission forecast for a baseline year and does not consider the wider implications in terms of environmental impacts or impacts to the individuals it directly affects.

We present a theoretical framework to aid decision makers to ensure energy justice is incorporated when designing CAPs. This framework expands on several key principles incorporated into the tenets of energy justice. These principles include energy availability, reliability and affordability, high-quality employment, access to information, objective governance, intersectional responsibility, intra-generational equity, intergenerational equity, and due process. This framework aims to reduce the disproportional burdens of transitioning towards a low carbon energy future by understanding why these key principles should be integrated into new and amended CAPs.
The Co-Effect of Root Exudates and Incubation Time on Solute Transport in the Rhizosphere
Authors: Paporisch Amit , Bavli Harel , Strickman Rachel J , Neumann Rebecca B , Schwartz Nimrod
Published: March 2022

Root exudates alter the rhizosphere’s physical properties, but the impact these changes have on solute transport is largely unknown. Additionally, root exudates enhance the microbial activity in soil, which may further change the rhizosphere’s physical properties, including solute transport. In this study, we tested the effects of chia mucilage and wheat root exudates on the transport of iodide in saturated soil. Solute breakthrough experiments, conducted in loamy sand soil or coarser textured quartz sand, revealed that increasing the exudate concentration in soil resulted in non-equilibrium solute transport. This behavior was demonstrated by an initial solute breakthrough after fewer pore volumes and the arrival of the peak solute concentration after greater pore volumes in soil mixed with exudates compared to soil without exudates. These patterns were more pronounced for the coarser textured quartz sand than for the loamy sand soil and in soil mixed with mucilage than in soil mixed wheat root exudates. Parameter fits to these breakthrough curves with a mobile-immobile transport model indicated the fraction of immobile water increased as the concentration of exudates increased. For example, in quartz sand, the estimated immobile fraction increased from 0 without exudates to 0.75 at a mucilage concentration of 0.2%. Saturated breakthrough experiments were also conducted in a loamy sand soil mixed with mucilage and incubated at 25 ºC for different time periods of up to 28 days. In this set of experiments, mucilage at a concentration of 0.2% in the soil had no effect on the iodide breakthrough curve prior to soil incubation, while 0.4% mucilage concentration altered the transport pattern (as described above), and its breakthrough curve pattern remained stable for the entire incubation period. However, after a 7-day incubation period, the breakthrough curve of soil with 0.2% mucilage concentration was also altered, again showing earlier breakthrough and later arrival of the peak iodide concentration compared to the breakthrough curve before incubation. This breakthrough pattern persisted for the remainder of the incubation period. The results of this study indicate that root exudates alter the rhizosphere’s transport properties and that enhanced microbial activity following root exudation may further affect solute transport. We hypothesize that this is due to exudates creating low-conducting flow paths that result in a physical non-equilibrium solute transport. Additionally, we hypothesize that enhanced microbial activity following root exudation results in secretion of extracellular polymeric substances and generation of biofilm that further affect the flow paths in soil, thus potentially altering solute transport in the rhizosphere with time.   
A new solution for displacements and gravity changes caused by pressurized (triaxial) ellipsoidal cavities in a half-space: source configuration and implications for joint inversions
Authors: Nikkhoo Mehdi , Rivalta Eleonora
Published: March 2022

Deformation source inversions have played a substantial role in our present understanding of magma plumbing systems at active volcanoes. Such inversions mostly rely on analytical models for uniformly-pressurized cavities as idealized representations of expanding magma bodies. The most common analytical cavity models used for rapid inversions are the isotropic point-source, the finite spheroidal cavity model and tensile dislocations or cracks. All these models have very specific shapes which cannot represent potentially significant deviations of magma chambers from axisymmetric geometries; thus, this aspect of volcano deformation sources has largely remained unexplored. Potential deviations from spherical and spheroidal shapes may explain the long-wavelength systematic residuals often encountered in inversions of deformation data. Even if the biases in the inferred deformation source parameters are small, they may translate into large biases in the mass change constrained through joint inversion of deformation and gravity data.
The next step to promote our understanding about volcano deformations is to explore these complexities in the source geometries and their implications. We develop a finite ellipsoidal cavity model (finite ECM) that is a solution for surface displacements and deformation-induced gravity changes caused by finite pressurized ellipsoidal cavities. The model can be used to constrain deformation source parameters and subsurface mass changes caused by magmatic intrusions and other processes pressurizing relatively shallow magma chambers. The model is in the form of a distribution of triaxial point sources with depth-dependent spacing and strengths. We systematically validate and benchmark the model by using analytical and numerical solutions. Also through these comparisons, we explore the limitations of the finite ECM. In particular, we analyze the biases in the inferred source depth, volume change and mass change due to the approximations inherent in the model. The finite ECM is computationally efficient and can be used for coupled inversions of deformation and gravity data.
A new method to detect changes in displacement rates of slow-moving landslides using InSAR time series
Authors: Urgilez Vinueza Alexandra Rocio , Handwerger Alexander L. , Bakker Mark , Bogaard Thom
Published: March 2022

Slow-moving landslides move downslope at velocities that range from mm year-1 to m year-1. Such deformations can be measured using satellite-based synthetic aperture radar interferometry (InSAR). We developed a new method to systematically detect and quantify accelerations and decelerations of slowly deforming areas using InSAR displacement time series. The displacement time series are filtered using an outlier detector and subsequently, piecewise linear functions are fitted to identify changes in the displacement rate (i.e., accelerations or decelerations). Grouped accelerations and decelerations are inventoried as indicators of potentially unstable areas. We tested and refined our new method using a high-quality dataset from the Mud Creek landslide, California, USA. Our method detects accelerations and decelerations that coincide with those previously detected by manual examination. Second, we tested our method in the region around the Mazar dam and reservoir in Southeast Ecuador, where the time series data were of considerably lower quality. We detected accelerations and decelerations occurring during the entire study period near and upslope of the reservoir. The application of our method results in a wealth of information on the dynamics of the surface displacement of hillslopes and provides an objective way to identify changes in displacement rates. The displacement rates, their spatial variation, and the timing of accelerations and decelerations can be used to study the physical behavior of a slow-moving slope or for regional hazard assessment by linking the timing of changes in displacement rates to landslide causal and triggering factors
The effects of seasonal wind regimes on the evolution of reversing dunes
Authors: Zhang Deguo , Chen Jie , Yang Xiaoping , Lehmkuhl Frank , Jiang Wubin
Published: March 2022

Seasonal changes in wind regime have driven the formation and emergence of reversing dunes and crest reversal in the inland arid and coastal areas of Asia, but due to the strong prevailing winds, the reversing dunes or reversing crest can be flipped. Therefore, the transient reversing dunes or crest reversal will be ignored and unobserved. To investigate dune morphology and sedimentology concerning seasonal alternation of the wind regime, we reconstructed dune topographies using aerial drone photos and analyzed the grain-size parameters and internal sedimentary structures of dunes. Morphological results show that wind-blown sands from the lee side are transported and deposited on the upper stoss side because of the reversing winds. Then, the dune crestal area is flattened, surface sand compositions were reorganized from fining to coarsening at the dune crest. Combining these field surveys with numerical simulation results, we found that the internal sedimentary structures are composed of high-angle cross-strata and low-angle bounding surfaces. The dip angles of the bounding surfaces gradually decrease from the bottom to the top because of the reversing wind erosion on the lee side. The increase in sand flux on the lee side plays a critical role in shaping the dip angle of the bounding surfaces due to the speed-up effect.
The future intensification of the North Atlantic winter storm track: the key role of dynamic ocean coupling
Authors: Chemke Rei , Zanna Laura , Orbe Clara , Zentman Lori , Polvani Lorenzo
Published: March 2022

Climate models project an intensification of the wintertime North Atlantic storm track, over its downstream region, by the end of this century. Previous studies have suggested that ocean-atmosphere coupling plays a key role in this intensification, but the precise role of the different components of the coupling has not been explored and quantified. Here, using a hierarchy of ocean coupling experiments, we isolate and quantify the respective roles of thermodynamic (changes in surface heat fluxes) and dynamic (changes in ocean heat flux convergence) ocean coupling in the projected intensification of North Atlantic storm track. We show that dynamic coupling accounts for nearly all of the future strengthening of the storm track as it overcomes the much smaller effect of surface heat flux changes to weaken the storm track. We further show that by reducing the Arctic amplification in the North Atlantic, ocean heat flux convergence increases the meridional temperature gradient aloft, causing a larger eddy growth rate, and resulting in the strengthening of the North Atlantic storm track. Our results stress the importance of better monitoring and investigating the changes in ocean heat transport, for improving climate change adaptation strategies.
Critical Infrastructure impacts of the 2021 mid-July western European flood event
Authors: Koks Elco , Van Ginkel Kees , Van Marle Margreet , Lemnitzer Anne
Published: March 2022

Germany, Belgium and The Netherlands were hit by extreme precipitation and flooding in July 2021. The event not only caused major damages to residential and commercial structures, but also to critical infrastructure in particular. Not only vital functions in the first response were affected (e.g. hospitals, fire departments), but also railways, bridges and utility networks (e.g. water and electricity supply) were severely damaged, expecting to take months to years to fully rebuild. This study provides an overview of the impacts to large-scale critical infrastructure systems and how recovery has progressed during the first six months after the event. The results show that Germany and Belgium were particularly affected, with many infrastructure assets severely damaged or completely destroyed. Impacts range from completely destroyed bridges and sewage systems, to severely damaged schools and hospitals. While some of the infrastructure systems, such as electricity, were relatively quickly restored (e.g. several weeks to a month), are others still not fully rebuild six months after the event (e.g. several road and railway bridges).  

We find that large-scale risk assessments, often focused on larger (river) flood events, do not find these local, but severe, impacts. On a local and regional level, the disruptions in daily lives and to the economy were enormous. Yet, zoomed out on a national scale, the impacts were relatively small. While large-scale studies are useful to identify potential hotspots and bottlenecks in the system, local-scale studies are essential to better understand the real impacts (and are also better able to do so). This may be the result of limited availability of validation material. As such, this study not only helps to better understand how critical infrastructure can be affected by flooding, but can also be used as validation material for future flood risk assessments that include critical infrastructure failure in their risk modelling framework.
The four levels of environmental storytelling
Authors: Gani Shahzad
Published: March 2022

In the face of major environmental issues such as climate change, air pollution, and biodiversity loss, communication of relevant expertise and experiences is extremely important. However, we also need to reflect on the scope, biases, limitations, and outright absences of the stories and storytellers. I propose a framework in which we consider four levels of environmental storytelling: (1) what stories are told? (e.g., funding agency priorities, editorial decisions), (2) whose stories are told? (people affected by theme selected, e.g., geography, race, socio-economic factors, gender), (3) who gets to tell the stories? (storytellers: journalists, communicators, scientists; their expertise and lived experience), and (4) what is the audience for the stories? (e.g., language, platform, jargon level, cost). By commission or omission, all these factors are part of the storytelling. All storytelling, including science communication, can become richer by reflecting on these multiple levels of storytelling.

I am developing this storytelling framework by drawing from my experience of hosting the Atmospheric Tales podcast (https://atmospherictales.com/) — a podcast which is now in its third year and features guests and interviewers from around the world with expertise and experiences on diverse themes related to climate change and air pollution including science, policy, advocacy, activism, etc.
Recovery & resilience of prehistoric societies after extreme events as viewed through palaeodemography
Authors: Riris Philip
Published: March 2022

The time taken by human societies to recover after extreme events is of widespread interest to archaeologists and anthropologists. To date, there has been no consistent, comparative study across prehistoric cultures to determine rates of recovery, their spatiotemporal variability, and the factors that affect outcomes. This talk will present a meta-analysis of palaeodemographic records that use archaeological radiocarbon dates as a proxy for prehistoric population history. It will initially draw on well-known case studies, with a view towards quantifying the geographical/biotic/cultural influences on societal recovery in the face of extreme events, as well as how different types of events may shape adaptive responses. In summary, the paper aims to advocate for rigorous and robust approaches towards past patterns of resilience, ideally ones that 1) focus on measurable, comparable properties of cultural dynamics, and 2) are linked more closely with interdisciplinary definitions of resilience, in order to enable large-scale syntheses of archaeological and anthropological data to inform future action.
Major CO2 losses from degradation of Mauritia flexuosa peat swamp forests in western Amazonia
Authors: Kristell Hergoualc’h , Jeffrey van Lent , Nelda Dezzeo , Louis Vincent Verchot , Jan Willem van Groenigen , Mariela Lopez , Julio Grandez-Rios
Published: March 2022

Tropical peat swamp forests are major global carbon (C) stores that are particularly vulnerable to human intervention. In the Peruvian Amazonia they have been severely degraded through recurrent cutting of Mauritia flexuosa palms for fruit harvesting, and potentially been transformed from a CO2 sink into a significant source. To estimate emissions associated with degradation, we combined C stock changes in aboveground biomass with peat C losses along a gradient comprising undegraded (Intact), moderately degraded (mDeg) and heavily degraded (hDeg) palm swamps. Temporal and spatial dynamics of the main components of the peat C budget (heterotrophic soil respiration (Rh) and litterfall) were investigated (bi)monthly over three years, while annual site-specific root C inputs and default dissolved organic C exports were taken from the literature. Variables measured at tree or microtopographic level were site-scaled considering forest structural changes from degradation. Site-scale litterfall (Mg C ha−1 year−1) at the hDeg site (2.3 ± 0.5) was less than half the rate at the Intact and mDeg sites (5.2 ± 0.9 and 6.0 ± 1.6, respectively). Conversely, site-scale Rh (Mg C ha−1 year−1) was higher at the hDeg site (9.6 ± 0.6) than at the Intact and mDeg sites (7.5 ± 1.1 and 6.1 ± 0.5, respectively). The peat carbon budget (Mg C ha−1 year−1) indicated that medium degradation reduced the sink capacity of the soil (from -1.8 ± 1.8 at the Intact site to -0.3 ± 0.7 at the mDeg site) while high degradation turned the soil into a high C source (6.0 ± 0.6 at the hDeg site). The large total C stock loss rates of 23.5 ± 14.3 and 57.7 ± 14.3 Mg CO2 ha−1 year−1 at the mDeg and hDeg sites, respectively, which originated 94 and 77% from aboveground biomass changes clearly highlight the need for sustainable management of these peatlands.