bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the contribution of charge exchange and Coulomb collisions to ring current proton dynamics with the new 4-D Proton Versatile Electron RadiationBelt (proVERB) code
Authors: Himmelsbach Julia , Allison Hayley , Shprits Yuri , Haas Bernhard , Wutzig Michael , Wang Dedong
Published: March 2022

Ring current particles affect the terrestrial magnetic field configuration, altering particle trajectories, as well as presenting a surface charging hazard for satellites. These particles can act as a seed population for the electron radiation belts and generate plasma waves. Accurately describing ring current dynamics is crucial to understand the near-Earth plasma environment. Here we report on our first results of the expansion of the Versatile Electron Radiation Belt (VERB) code to model ring current proton dynamics (proVERB). We perform sensitivity studies for the four dimensional grid, considering the grid resolution necessary to resolve proton dynamics. Analysing the banana shaped orbits for ring current protons shows that the azimuthal grid resolution is comparable to the electron grid, while the resolution in the radial grid has to be significantly enhanced. Loss mechanisms of charge exchange and Coulomb collisions, thought to be largely responsible for the decay of the ring current during the recovery phase of a storm, are included in proVERB. We present our first simulation results and compare them to observations from the Van Allen probes HOPE and MagEIS instruments. By retaining and omitting charge exchange and Coulomb collisions in our simulations, we study the role of these loss processes on the ring current evolution during active periods.
Dispersion of motile bacteria in a porous medium: Experimental data and theory
Authors: Dentz Marco , Creppy Adama , Douarche Carine , Clément Eric , Auradou Harold
Published: March 2022

The sound understanding and quantification of the transport and dispersion
mechanisms of bacteria in porous media is of central concern in applications
such as bioremediation and biomineralization. Recent experimental and numerical
studies indicate that motility plays a key role for the fate of bacteria.
Data from microfluidic experiments in model porous media consisting of randomly
placed pillars show that non-motile bacteria have compact displacement
distributions, while the distribution of motile bacteria are characterized by
strong peak retention and forward tailing. Detailed analysis of bacteria
trajectories reveals two key attributes: 1. The emergence of a motility-induced
trapping and retention process due to active motion from the stream toward the
solid grain. 2. Increase or decrease of dispersion due to the transfer between
pore channels and grains, depending on the flow rate. We develop a physical model
based ona continuous time random walk (CTRW) approach. Bacteria dispersion due to
hydrodynamic flow fluctuations is quantified by a Markov model for the equidistantly
sampled particle speeds. The impact of motility is modeled by a two-rate trapping
process that accounts for the motion toward and active trapping at the grains.
The theoretical model captures the displacement distributions of both non-motile
and motile bacteria. It provides explicit analytical expressions for the motility-induced
hydrodynamic dispersion coefficients in terms of the trapping and release rates,
which characterize the bacteria motility. The experimental data shows that these
motility parameters are flow-rate dependent, which manifest in a reduction of
dispersion compared to the non-motile bacteria at low flow rates, and an increase
at high flow rates. The model reproduces the experimental observations and allows to
predict bacteria dispersion at the continuum scale.  
Using satellite geodesy for carbon cycle research 
Authors: Klemme Alexandra , Warneke Thorsten , Bovensmann Heinrich , Weigelt Matthias , Müller Jürgen , Notholt Justus , Lämmerzahl Claus
Published: March 2022

To assess realistic climate change mitigation strategies, it is important to research and understand the global carbon cycle. Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. Their atmospheric concentrations are affected by anthropogenic emissions as well as exchange fluxes with oceans and the terrestrial biosphere. For the prediction of future atmospheric CO2 and CH4 concentrations, it is critical to understand how the natural exchange fluxes respond to a changing climate. One of the factors that impact these fluxes is the changing hydrological cycle.        
In our project, we combine information about the hydrological cycle from geodetic satellites (e.g. GRACE & GRACE-FO) with carbon cycle observations from other satellites (e.g. TROPOMI & OCO-2). Specifically, we plan to investigate the impact of a changing water level in soils on CH4 emissions from wetlands and on the photosynthetic CO2 uptake of plants. Details of our approach and first results will be presented.
Towards a new ITSG-Grace release: updated data products and improvements within the processing chain
Authors: Mayer-Guerr Torsten , Behzadpour Saniya , Kvas Andreas , Krauss Sandro , Strasser Sebastian , Süsser-Rechberger Barbara
Published: March 2022

The Institute of Geodesy of the Graz University of Technology has a successful record in producing GRACE/GRACE-FO gravity fields using an in-house developed software, the Gravity Recovery Object Oriented Programming System (GROOPS). The ITSG-Grace2018 gravity field model is the latest release of the ITSG sequence covering the complete GRACE/GRACE-FO time-span. The new release will be based on planned Level-1B Release 05 data and the AOD1B Release 07 dealiasing product. It will include a static field, unconstrained monthly, as well as Kalman smoothed daily solutions.

Updates and improvements over the previous release are summerized as follows: (a) We revisit the Level-1A processing of transplant accelerometer data and co-estimate their unmodeled linear accelerations due to thruster activities; (b) We improve the estimation of subdaily high-frequency mass variations by increasing both temporal and spatial resolutions; (c) Taking advantage of the available GRACE-FO LRI measurements, we introduce combined KBR and LRI gravity field solutions based on a stochastic modeling that determines proper weighting between KBR and LRI observations.

This contribution will highlight the selected parts of the processing chain and their effect on the estimated gravity field solutions.
Characterizing dust aerosols with lidar and UAV based measurements (Cyprus Fall campaign 2021).
Authors: Papetta Alkistis , Kezoudi Maria , Marenco Franco , Keleshis Christos , Mamouri Rodanthi-Elisavet , Nisantzi Argyro , Sciare Jean
Published: March 2022

Due to its geographical location, Cyprus is often affected by dust storms arriving from the largest deserts of the planet, the Sahara, the Arabian Peninsula and  the Syrian. In order to characterize dust properties, the Cyprus Atmospheric Observatory (CAO) and the Unmanned Research Laboratory (USRL) of the Cyprus Institute (CYI), in collaboration with the Cyprus Atmospheric Remote sensing Observatory (CARO) of the ERATOSTHENES Centre of Excellence (ECoE) of the Cyprus University of Technology (CUT), performed a research campaign in Fall 2021. Measurements were performed with ground-based aerosol remote sensing systems (lidars, ceilometers and sunphotometers), and UAV based in-situ instruments (OPCs, backscatter sondes, and impactors able to collect dust samples). As part of the  remote sensing observations, two depolarized lidars performed measurements from different locations, one from CYI premises in Nicosia and the second one from ECoE-CUT premises in Limassol. The lidar signals provide information about the vertical aerosol profile at the two locations, which can be used to derive the optical properties of dust at different altitudes. Here, we will present first results on the synergy between the continuous vertically extended measurements of lidars and the in-situ measurements from UAV instrumentation during the periods of dust outbreaks. Two dust events occurred from 25 October to 1 November and from 13 to 18 November 2021. During these dust events, the lidars observed depolarized aerosol layers from ground up to 5 km above sea level. The lidar measurements provided the temporal and spatial development of these dust layers, and were also used in real-time for planning the UAV flight schedule. According to backward trajectory analyses, the two dust events had different origins with the first arriving from the Sahara and the second one from the Middle East.
How to turn satellite data to insights at scale
Authors: Goussard Basile
Published: March 2022

NetCarbon, a brand new french startup company, is offering farmers a free solution for measuring and monetizing their sequestered carbon to contribute towards carbon neutrality. This solution is relying on satellite data (Sentinel 2, Landsat 8 & PlanetScope) and open-source ecosystems such as the Pangeo software stack

 

The challenge in NetCarbon’s solution is the deployment of earth observation insights at scale. And be able to shift between cloud providers or on-premise architecture if needed. The best tool for us is up-to-now PANGEO.  

 

An example of our pangeo usage will be shown in the following three points.   

1°) Connection to satellite data / Extract 

2°) Processing satellite data at scale / Transform

3°) Saving the data within a data warehouse / Load

 

First, some of the building blocks to search for satellite data based on STAC will be shown. Moreover, the stackstac package will be tested to convert STAC into xarray, allowing researchers and companies to create their datacubes with all the metadata inside. 

 

The second part of the presentation will involve the computation layer. Indeed, computations algorithms like filtering by cloud cover, applying cloud mask, computing the land surface temperature, and applying an interpolation will be run. Land surface temperature is one data needed for the NetCarbon algorithm. The result of these previous steps will lead us to retrieve a dask computation graph. This computation graph will be run at scale within the cloud, based on Dask and Coiled. 

 

To conclude, the output of the processing part (spatial and temporal mean of the land surface temperature) will be displayed within a notebook and finally, the data will be loaded into a data warehouse (google bigquery). 

 

All the steps will be demonstrated in a reproducible notebook
What can high resolution ice surface observations tell us about the bed topography of Pine Island Glacier, West Antarctica? 
Authors: Ockenden Helen , Bingham Rob , Curtis Andrew , Goldberg Daniel , Giannopoulos Antonios
Published: March 2022

The West Antarctic Ice Sheet has the potential to contribute up to 3m of sea level rise over the next few centuries. There is considerable uncertainty over the rate at which ice loss will occur, caused in part by a lack of knowledge about the bed topography beneath the ice sheet, which influences ice flow and retreat. Since direct bed topography observations are often further apart than ice sheet models require, we explore instead what we can learn about bed topography from high resolution observations of the ice surface, which are openly available. We apply an inversion methodology based on linear perturbation theory and developed by Gudmundsson (2003, 2008) to ice surface data from Pine Island Glacier, and present the bed topography results. Comparison to high-resolution radar sounding of the bed topography of Pine Island Glacier from the iSTAR 2013-14 ground surveys allows us to assess the success of the inversion methodology. We identify regions of the glacier where the landforms we see are likely to be artefacts, and regions where unknown and interesting landforms are likely to exist. This methodology has the potential to be extremely useful in regions where direct observations of bed topography are sparse, and for identifying areas where more observations would be of particularly high benefit.   
Modelling debris-flow source-area connectivity and impacted stream channels in the semi-arid central Andes of Chile using random walks and network analysis
Authors: Goetz Jason , Buchhart Max , Brenning Alexander
Published: March 2022

In the last decade, major debris flows events in remote areas of the semi-arid central Andes of Chile have led to critical water supply shortages for large populated areas such as Santiago de Chile. There is therefore a crucial need for modelling debris-flow sediment connectivity to stream channels to identify both vulnerable stream channel sections and sediment source locations to focus mitigation efforts to ensure the reliability of drinking water supplies. In this research, we couple a statistical learning model of debris flow source areas with a process-based random-walk runout simulation to estimate the probability of source areas connecting to stream channel networks in a large catchment area of the upper Maipo river basin using a 12.5 m resolution digital elevation model. The runout model parameters are regionally optimised and validated using a spatial cross-validation approach.   Additionally, we perform network analysis to model the cumulative impact of potential debris flow sediment delivery to the stream channel network. The proposed methods are also designed for flexibility to adapt for assessing potential debris flow impacts and source areas corresponding to other critical features such as roads and buildings. Overall, the resulting predictive models of  runout sources and impacted areas provide not only valuable insights for characterising the potential impacts of debris-flows on stream channel networks, but also provides a model framework that can be potentially linked to weather forecast data for establishing early-warning systems of debris-flow related water supply shortages and quality issues in remote areas. 
Biomarker evidence for bacterial oxidation of oil-derived hydrocarbons at seeps in the southern Gulf of Mexico
Authors: Krake Nicola , Birgel Daniel , Smrzka Daniel , Zwicker Jennifer , Huang Huiwen , Feng Dong , Bohrmann Gerhard , Peckmann Jörn
Published: March 2022

Hydrocarbon seepage is a widespread phenomenon at continental margins around the world. The composition of the ascending fluids can be variable, consisting of short- and long-chain hydrocarbons as well as crude oil. A prominent site of oil seepage is the Bay of Campeche in the southern Gulf of Mexico. The seepage of petroleum is known to have an inhibiting effect on life at seeps, but short- and long-chain hydrocarbons have been shown to be degraded by a range of heterotrophic sulfate-reducing bacteria. Here we present lipid biomarker and carbon isotope data from authigenic carbonates from the Campeche Knolls in the southern Gulf of Mexico. The Campeche carbonates display d13C values in the range of -31.3‰ to -21.9‰, which is in accord with carbon derived from oil-derived hydrocarbons. Interestingly, the Campeche carbonates contain particularly high amounts of bacterial non-isoprenoidal ether lipids (DAGEs) with a wide variety of alkyl chain lengths. The bacterial biomarkers show heavier carbon isotopic signatures than their counterparts at methane seeps. These data allow for the characterization of bacterial oxidation of oil-derived hydrocarbons in modern and, in cases of moderate to good biomarker preservation, ancient environments, permitting the assessment of the influence of different fluid chemistries on the composition of chemosynthesis-based communities at seeps.
On the origin of the pulsing activity in powder snow avalanches
Authors: Sovilla Betty , Kyburz Michael , Ligneau Camille , Pérez- Guillén Cristina , Huguenin Pierre , Hohl Michael , Gaume Johan
Published: March 2022

Powder snow avalanches (PSAs) are a major threat to people and infrastructure in many mountainous regions of the world. Their force is enough to easily destroy mature forests and any infrastructure located along their path. This is to some extent related to the high velocities and flow heights they can develop, but the basic physical mechanisms controlling their destructiveness remain unclear. Part of this insecurity is related to the fact that the structure of a PSA is very complex. In fact, it can be visualized as the superposition of three distinct layers: (i) a dense granular basal layer, (ii) a transition layer in the form of a turbulent flow with strong density stratification, and (iii) a dilute turbulent suspension of finer particles covering the whole.

Experimental data collected at the Vallée de la Sionne avalanche test site (VdlS) in Switzerland suggests that the destructive capacity of PSAs is largely related to high-energy pulses within this complex stratification. This data indicates that there are at least three different physical processes at the origin of the pulses, specifically: (i) waves at the surface of the dense basal layer (e.g roll-waves, erosion-deposition waves), (ii) coherent vertical structures within the transition layer, and (iii) coherent turbulence structures in the suspension layer. All of these processes, which can also coexist, can be associated with maxima in the dynamic pressure measured over a fixed obstacle.

Although the origin of these pulses still remains largely speculative, with this contribution we aim to present experimental evidence for the existence of various mechanisms of pulsing in PSAs and discuss their relevance in terms of dynamic pressure calculations.
Experimental observations of rupture nucleation phase on heterogeneous interface
Authors: Gounon Alisson , Latour Soumaya , Letort Jean
Published: March 2022

With friction experiments, we investigate the rupture dynamics process, in particular the nucleation part, of laboratory earthquakes conducted on a periodically heterogeneous interface between two polycarbonate plates. Thanks to photoelasticity we follow the evolution of rupture front along the fault over time and we estimate the stress-drop with a strain gauge localized at the center of the fault.

We observe that the nucleation process generally does not consist of a monotonic growth observed on homogeneous cases, but of an alternation between slow and fast parts that accelerates until it reaches a point at which fast propagation dominates. Those alternations are correlated with the position of heterogeneities on the interface. Moreover, we observe that nucleation process of ruptures with smaller stress drop last longer than ruptures with a higher stress drop. Finally, we also point out a large variability in the rupture process due to the balance between the friction heterogeneity and the uncontrolled stress heterogeneity.
Late Holocene climatic variability in Southern Spain deduced from the sedimentary record of Laguna Grande de Archidona
Authors: Castillo Baquera Aurora , Garcia Alix Antonio , Gazquez Fernando , Jimenez Moreno Gonzalo , Rodriguez Rodriguez Miguel , Jimenez Espejo Francisco
Published: March 2022

The southern Iberian Peninsula has been especially sensitive to Holocene climate changes [1]. Climatic and environmental variability has been reconstructed by the mineralogical and chemical analyses of lacustrine sediments. In this study we show the preliminary chronological, lithological, geochemical and magnetic susceptibility results of the sedimentary record of the Laguna Grande de Archidona (southern Spain). This record covers the last 3300 years and it reveals three paleoenvironmental stages. (1) A phase of relative aridity occurred between 3300-3000 cal yr BP, evidenced by fluctuating values of magnetic susceptibility and the presence of gypsum levels, which suggest high evaporation and fluctuating detritic inputs to the lake. (2) A humid phase is identified from 3000 to 1500 cal yr BP, deduced by significant detritic inputs to the lake (high magnetic susceptibility values) due to high catchment runoff during this period. This was the most humid period in the record, agreeing with other regional paleoclimatic records of the Iberian Roman Humid Period (2800-1500 cal yr BP [2]). Additionally, smaller-scale climatic oscillations are shown by the Sr/Al ratio fluctuations and the alternance of some carbonate and gypsum levels during this period. (3) Finally, all the proxies show abrupt changes and higher variability during the last 1500 years, depicting an aridification trend. This paleoenvironmental and paleoclimatic reconstruction agrees with previous studies from the southern Iberian Peninsula that show an arid phase between 3300-3000 cal yr BP, most-likely related with pervasive positive NAO conditions [3], and a decrease in arboreal pollen in Sierra Nevada sites (e.g.,  Borreguil de la Caldera [4]). A humid phase is identified during the Iberian Roman Humid Period, coeval with a dominant NAO negative mode [3] and also identified by enhanced erosion rates in other southern Iberia areas, such as in Zoñar lake [2] and by the increase of arboreal pollen in several records [1]. Finally, a trend towards more arid conditions is registered after 1500 cal yr BP in southern Iberia records, such as in Zoñar lake, which shows runoff decrease [2], or in other sites of southern Iberia that exhibit an increase in grasses [1, 5].

 

[1] Ramos-Román et al. (2018), Climate of the Past 14, 117-137; [2] Martín Puertas et al. (2010), Climate of the Past 6, 807-816; [3] Olsen et al. (2010) Nature Geoscience 5, 808-812; [4] Ramos-Román et al. (2016), Quaternary Science Review 143, 84-95; [5] Jiménez-Moreno and Anderson. (2012), Quaternary Research 77, 44-53.
Study of historical evolution (1979-2014) of key water cycle variables in the pyrenees using observations and modeled data
Authors: Clavera-Gispert Roger , Quintana-Seguí Pere , Beguería Santiago , Palazón Leticia , Zabaleta Ane , Cenobio Omar , Barella-Ortiz Anaïs
Published: March 2022

The natural border between Andorra, France and Spain are the Pyrenees, a South-Western European mountain range with a great environmental diversity: from Atlantic to Mediterranean climates, from high mountains to cliffs touching the sea, and from humid to semi-arid  conditions. Thus this region is particularly sensitive to climate and global change. On the other hand, this territory is the primary source of water in the region, feeding the runoffs and recharge zones of the region's main catchment basins. Rapid changes in the environment can have an influence on the availability of water resources downstream, increasing the uncertainty to an already tough water management situation.

Scientists use hydrological data to detect and quantify climate variability and change. Although data from gauging stations are basic to study the temporal evolution of water resources, more than these punctual data are needed for a regional study, as many relevant variables of the water cycle, such as evaporation, are seldom observed. Furthermore, models are necessary to study the future climate, but we need first to check if the models faithfully reproduce the intended processes. Therefore, hydrological modeling plays an important role in water resources studies, as they allow us to quantify the main components of the water balance (precipitation, evapotranspiration, drainage/recharge, runoff and streamflow) and the main stocks (soil moisture and snow) for the entire region. 

We have used observation values from non-influenced gauging stations and hydrological outputs of two different modeling tools (the fully distributed model SASER, and the semi-distributed model SWAT) to study the historical evolution (1979-2014) of the natural continental water cycle in the Pyrenees. The comparison of observational data with models, as well as models between them, will allow us to detect, evaluate and analyze the main sources of uncertainty.

We computed monthly, seasonal and annual statistics for three time periods (1979-2014, 1989-2014 and 1999-2014). Thus, we made and analyzed trends for the time series of the different variables applying a time series pre-whitening. These trends have been calculated with the Sen's slope estimator assuming that they are linear. The significance of the trends was estimated with the Mann-Kendall test on the pre-whitened time series with the statistical significance tested at the 95% level.

This work is a contribution to the EFA210/16 PIRAGUA project.
Proton precipitation in a hybrid-Vlasov simulation with southward interplanetary magnetic field driving: First 3D results
Authors: Grandin Maxime , Luttikhuis Thijs , Alho Markku , Battarbee Markus , Bussov Maarja , Cozzani Giulia , Dubart Maxime , Ganse Urs , George Harriet , Horaites Konstantinos , Manglayev Talgat , Papadakis Konstantinos , Pfau-Kempf Yann , Suni Jonas , Tarvus Vertti , Turc Lucile , Zaitsev Ivan , Zhou Hongyang , Palmroth Minna
Published: March 2022

The precipitation of charged particles from the magnetosphere into the ionosphere is one of the crucial coupling mechanisms between these two regions of geospace. While precipitating particle fluxes have been measured by numerous spacecraft missions over the past decades, it often remains difficult to obtain global precipitation patterns with a good time resolution during a substorm. Numerical simulations can contribute to bridge this gap and help improve the understanding of mechanisms leading to particle precipitation at high latitudes through the global view they offer on the near-Earth space system. We present the first results on proton precipitation within a 3-dimensional simulation of the Vlasiator hybrid-Vlasov model. The run is driven by southward interplanetary magnetic field conditions with steady solar wind parameters. We analyse the large-scale proton precipitation pattern in both hemispheres and discuss its dynamics in relation to the processes taking place in the magnetotail.
Global hotspots of nitrous oxide mitigation potentials in croplands 
Authors: Zhou Feng , Cui Xiaoqing
Published: March 2022

Mitigating soil nitrous oxide (N2O) emissions is essential for staying below a 2°C warming threshold. However, accurate assessments of mitigation potential are limited by uncertainty and variability in direct emission factors (EFs). To assess where and why EFs differ, we create high-resolution maps of crop-specific EFs based on 1,507 georeferenced field observations. Here, using a data-driven approach, we show that EFs vary by two orders of magnitude over space. At global and regional scales, such variation is primarily driven by climatic and edaphic factors rather than the well-recognized management practices. Combining spatially explicit EFs with N surplus information, we conclude that global mitigation potential without compromising crop production is 30% [95% CI: 17-53%] of direct soil emissions of N2O, equivalent to the entire direct soil emissions of China and the United States combined. Two thirds (65%) of mitigation potential could be achieved on one fifth of global harvested area, mainly located in humid subtropical climate and across gleysols and acrisols. These findings highlight the value of a targeted policy approach on global hotspots that could deliver large N2O mitigation as well as environmental and food co-benefits.
Global impact of benthic denitrification on diazotroph physiology and N2 fixation rates
Authors: Li Na , Somes Christopher , Landolfi Angela , Chien Chia-Te , Pahlow Markus , Oschlies Andreas
Published: March 2022

Nitrogen (N) is one of the crucial limiting nutrients for phytoplankton growth in the ocean. The main source of bioavailable N to the ocean is N2-fixing diazotrophs in the surface layer. Since the global coverage of N2 fixation observations is sparse on temporal and spatial scales, the fundamental processes and mechanisms controlling N2 fixation are not well understood nor constrained. We implement benthic denitrification in the optimality-based plankton ecosystem model (OPEM), which is incorporated into an Earth System Model of intermediate complexity (UVic-ESCM 2.9). Benthic denitrification occurs mostly in coastal upwelling regions and shallow continental shelves, and affects significantly the marine fixed-N budget since it is the largest N-loss process in the global ocean. We carry out model calibration and parameter selection based on observations of Chl, NO3-, PO43-, O2 and N*=NO3--16PO43-. Compared to considering water-column denitrification in suboxic zones as the only N-loss process in the ocean, our new model version simulates a more realistic distribution and higher global rates of N2 fixation, which are supported by independent rate measurements. The optimized cellular N:P ratios of diazotrophs in the model version with benthic denitrification better correspond to independent culture estimates, and result in a closer reproduction of the particulate N:P ratios. Our model results indicate that benthic denitrification plays an important role shaping patterns, rates and even physiological aspects of N2 fixation throughout the global ocean and should be accounted for when understanding and predicting changes to N2 fixation. 
Road influences on landslide inventories 
Authors: Malamud Bruce D. , Heijenk Renée A. , Taylor Faith E. , Wood Joanne L.
Published: March 2022

Roads can both increase and decrease the likelihood of landslides occurring in a given region. This might be due to (i) mapping biases when compiling landslide inventories, (ii) the influence of the road on the landslide susceptibility. Here, we present a spatial statistical analysis of landslide proximity to roads across a range of geographic settings and landslide inventory types. We examine the proximity of landslide centroids to roads at regional to national scales using 12 diverse landslide inventories with variations in inventory type (6 triggered event, 6 multi-temporal), mapping method (1 field-based, 6 remote sensing, 5 a combination of mapping methods), and countries of origin distinguished by their human development index (HDI) (6 high and 6 low HDI). Each inventory contains 270 < nLandslides < 81,000 landslides with inventory regional extents ranging from 80 km2 < Ainventory < 385,000 km2. We have developed a PyQGIS tool that calculates the distance between each landslide centroid and the closest road vector within the same watershed. From these distance values, we create a density distribution of landslides as a function of distance from roads for that inventory. We then compare each inventory’s density distribution of landslide-to-road distance to a set of randomly generated points and their distances to roads. For the 12 inventories, we find that the landslide density near roads compared to random points is greater in 3 inventories, equal in 3 inventories, and lower in 6 inventories. We find that a comparison between landslides and random points describes each inventory well in terms of road density. We divide the 12 inventories into 4 typologies with different potential explanations for each group. We believe there is evidence of mapping bias towards roads for the typology with 3 inventories that have greater landslide density (compared to random points), which suggests that a more nuanced use of road proximity within landslide susceptibility models should be adopted. Further research should be done to understand the interactions between landslides and proximity to roads at the regional to national scale.
Fully coupled 3D Thermo-Hydro-Mechanical analyses of a single Energy Micropile subjected to heating-cooling cycles
Authors: Salciarini Diana , Lupattelli Arianna , Ronchi Federica
Published: March 2022

Energy Geo-Structures are being increasingly employed over the last decade. They combine the structural and energetic function, allowing the savings related to the absence of additional drilling, required instead by the common geothermal boreholes. Currently, they are a rather mature and deeply investigated technology, with a number of successful applications worldwide; however, some issues related to the thermo-hydro-mechanical (THM) effects induced in soils during heating/cooling cycles still deserve some more analyses, particularly for what concerns the possible non-linear behavior of soil under thermal loading. In this work, this issue has been investigated by means of fully coupled 3D FE modeling, considering a single, small diameter Energy Pile. The emphasis of the FE numerical modeling activity is the investigation of the effects induced by the pore pressure variations close to the pile during the thermal loading stage, and the assessment of the potential influence of the soil thermal softening effect on the pile behavior. Two different constitutive models have been adopted for the considered fine–grained soil, both based on the standard critical state theory: i) the classical Modified Cam Clay (MCC) model; and, ii) a similar critical state model incorporating a thermal hardening/softening mechanism for the critical friction angle, assumed as an internal variable that can be modified with temperature. In the FE model, first the mechanical load is applied at the pile head in almost undrained conditions, followed by a consolidation period during which the excess pore pressure dissipates. Thus, the pile is thermally loaded, with the temperature that is assumed to vary with a harmonic function law over periods of 1, 5 and 10 years, to investigate the short term and long–term effects. The results show that: a) for the considered case study, the thermal loading conditions produce very small changes in pore water pressure at the pile-soil interface; and no effects observed on the pile head displacements can be related to thermally-induced pore pressure changes; on the contrary, b) significant additional pile head settlements are observed in presence of thermal softening, due to by plastic shear deformations at the soil-pile interface.
New way to predict sediment production and deposition around a mountain belt : integrated Source to Sink palaeogeological maps.
Authors: Lasseur Eric , Ortiz Alexandre , Fillon Charlotte , Briais Justine , Guillocheau Francois , Bessin Paul , Baby Guillaume , Baptiste Julien , Uzel Jessica , Robin Cecile , Calassou Sylvain , Frasca Gianluca , Castelltort Sebastien
Published: March 2022

The knowledge acquired on the exhumation of the Pyrenean mountain belt and the evolution of the adjacent foreland basins makes this Alpine-type domain a good laboratory to better constrain a full sediment routing system in a compressive context and to apprehend the driving processes controlling the sediment routing in space and time. This integrated approach aims at enhancing our basin mastering approach as well as improving our predictions of reservoir properties.

This Source-to-Sink study seeks to understand the evolution of sedimentary routing from the Source (orogenic relief, craton, basin recycling) through the transfer zone (peripheral or internal to the basin) to the final sink (flexural basin, deep turbiditic margin). Within this new cartography, we propose to compile the data over the entire peri-Pyrenean domain. We produced large scale quantitative and qualitative maps to better observe and interpret the tectonic, climatic and surface processes impacts of the SRS behavior.

These maps include kinematic reconstructions of the Iberian-European-Mediterranean system, restored sequential cross-sections, history/magnitude of exhumation by thermochronology, source tracking, characterization of weathering and erosion surfaces, synthesis of the major structures activity, paleogeographic reconstructions, analysis of sedimentary geometries and transport directions as well as the quantification of volumes preserved in the basins. Their interpretation is combined with a time representation along the routing system, linking classical basin wheeler diagram representation to source erosion and lithologies to obtain a continuous view on the sediment journey.

The time steps chosen for these 5 maps account for the different stages of tectono-sedimentary evolution of the peri-Pyrenean system at the early-, syn- and post-orogenic stages. The compilations carried out compare exhumed domains and sedimentation zones in terms of fluxes and volumes and make it possible to map the routing systems and point out the main drivers for the surface evolution during the construction/destruction cycle of an orogen. This research work was financed and carried out as part of the BRGM-TOTAL Source-to-Sink program
Tomographic 3D reconstructions of artificial releases of SO2 in the atmospheric boundary layer
Authors: Pisso Ignacio , Cassiani Massimo , Stebel Kerstin , Kylling Arve , Dinger Anna Solvejg , Ardeshiri Hamidreza , Park Soon-Young , Schmidbauer Norbert , Stohl Andreas
Published: March 2022

Turbulence in the planetary boundary layer controls the exchange fluxes of passive and active tracers between the Earth’s surface and the atmosphere. In climate and meteorological models, such effects of turbulence need to be parameterized, ultimately based on experimental data. A modeling/experimental approach was developed within the COMTESSA project to study turbulence statistics. Using controlled tracer releases, UV camera images and estimates of the background radiation, different tomographic algorithms were applied to obtain time series of 3D representations of the scalar dispersion. We used initially synthetic data to investigate different reconstruction algorithms with emphasis on algebraic iterative methods, studying the dependence of the reconstruction quality on the discretization resolution and the geometry of the experimental device in both 2D and 3D cases. For the iterative methods we assessed the computational aspects of the iterative algorithms focusing of the phenomenon of semi-convergence applying a variety of stopping rules. In addition to the synthetic studies, we present actual tomographic 3D reconstructions of artificial SO2 puffs using multiple camera measurements from the experimental campaigns in Norway.
Isolating bed load transport from river induced seismic signals
Authors: Matthews Bronwyn , Naylor Mark , Sinclair Hugh , Dietze Michael , Williams Richard , Cuthill Calum
Published: March 2022

Bed load transport is a critical parameter in the study of landscape evolution and also provides valuable information for problems in the fields of ecology, river and landuse management, and civil engineering. Bed load transport is difficult to assess due to its stochastic nature and highly variable transport rates, and traditional measurement techniques have struggled to capture the spatial and temporal variability of bed load transport. In recent years, bed load monitoring based on seismological observations has emerged, which allows non-invasive and continuous indirect measurements. However, there still remains a significant challenge to independently characterise the seismic signature of bed load from other sources of noise, such as turbulence. Our study aims to explore seismic data recorded at the highly braided River Feshie in Scotland, which has undergone significant morphological change in its history and has been highly monitored over the last couple decades through Digital Elevation Models. Since the deployment of our seismometers in December 2020 we have captured three independent high flow events plus an isolated earthquake, which are being used to determine the environmental signals and the site specific signal characteristics. In some previous studies, an observed hysteretic relationship between seismic power and hydrological parameters has been interpreted as being characteristic of bed load transport. From the data we have gathered we have observed a hysteresis in the signals, and through Shields calculations it is suggested that bed load transport would be expected during these events. However, without independent constraints we do not feel we can be absolutely certain that this behaviour is a result of bed load transport. Our ongoing study therefore aims to combine multiple physical measurement techniques, such as hydroacoustic measurements, time-lapse imagery and seismic observations, to try and pinpoint what is contributing to the seismic signals recorded and how we can isolate the bed load transport component.
Water quality is exciting even during a pandemic: students measure and interpret nitrate concentrations using the Nitrate App
Authors: Lutz Stefanie , Rozemeijer Joachim , Buijs Simon , Ekkelenkamp Rudie
Published: March 2022

The Covid-19 pandemic has severely affected possibilities for students to do field work and thereby train their team work skills. Under the uncertain conditions of the pandemic, teachers might be reluctant to plan field courses months ahead, and students and teachers might not feel comfortable or are simply not allowed to travel in larger groups. This calls for approaches that allow students to do field work in small groups in their own time and to integrate individual group results into a course-wide learning goal. In this contribution, we will share our experiences with the Nitrate App developed by Deltares, which enables students to do water quality measurements with minimal prior instructions and without supervision by teachers. The Nitrate App is a smartphone application that reads nitrate concentrations from test strips and stores them in a shared database. The app has been originally developed to support farmers in measuring nitrate concentrations and derive best management practices from these. While farmers make great use of this application, the Nitrate App has been increasingly employed for educational purposes. At the same time, educational use of this app can also feed back into water management, as this allows collecting nitrate concentration data at much finer spatial resolution than possible in regional water quality monitoring networks. The directly available measurement results allow for ad hoc decisions about measurement strategies for example to identify the source of high nitrate concentrations. We will illustrate recent examples of how the Nitrate App has been employed in field work assignments of Bachelor’s and Master’s geoscience courses as well as in elementary school education.
Along-strike variations of salt-related structural style in the Western Alps
Authors: Csicsek Adam , Célini Naïm , Callot Jean-Paul , Ringenbach Jean-Claude , Graham Rodney , Brooke-Barnett Sam , Lonergan Lidia
Published: March 2022

The Upper Triassic evaporites of Western Europe, also known as the ‘Keuper’, are well-known and have been mostly considered as an efficient décollement level for the thrusts of the external fold-and-thrust belts. Numerous recent studies aimed to reappraise their role, and especially the role of salt tectonics, in the formation of several mountain belts such as the Pyrenees, the Betics, Provence, and the Alps.

The Western Alps represent a good laboratory to study the role of salt in shaping a mountain belt because it contains areas with (1) no evaporites, (2) evaporites involved as an efficient décollement level during orogeny and (3) evaporites mobilised in salt tectonics since the Lias rifting. We propose here, based on literature and our recent works regarding salt tectonics in the SW Alps, to present and discuss the different salt-related structural styles observed along-strike the Western Alps. A focus will be done on the SW Alps where evaporites influence their structure during the whole Alpine history from rifting until collision. They were mobilised by the Lias rifting through reactive diapirism. Salt tectonics carried on during the post-rift period by passive diapirism, controlled by sediment loading. A few structures were reactivated during the Oligocene and in places evaporites influenced the structure of the subalpine chains until the Mio-Pliocene.

Our study shows that evaporites strongly influence the structure of a mountain belt at different scales and that along-strike variations of structural style are observed along the strike of the Western Alps depending on the presence, the amount or the absence of evaporites.
Impact of satellite image pairs selection when deriving ice velocities trends
Authors: Halas Paul , Mouginot Jeremie , de Fleurian Basile , Langebroek Petra
Published: March 2022

When assessing ice velocity trends in Greenland, optical feature-tracking has previously been used to derive one-year velocity averages. Indeed, this technique requires pairs of images separated by approximately one year, and usually all possible pairs are used in order to achieve the best spatial coverage for every year. But this implies averaging pairs that start at different time in the year, and it is common to also use pair of images that are separated by shorter or longer time (ranging from 336 days up to 400 days between images).

Since ice velocities display strong seasonal variations, we argue that combining all pairs may impact the yearly ice velocities estimations by sampling differently summer and winter velocities, and therefore impacting the long-term trends.

Here we assess this impact by reproducing the work done from previous studies (Tedstone et al. 2015, Williams et al. 2020) using optical feature-tracking on Landsat-5, 7 and 8 as well as Sentinel-2 constellation, focusing on land-terminating parts of the Southwest of Greenland Ice sheet, and by comparing obtained velocity trend maps with trends of the same area obtained when operating a precise selection of the data.

 
Paleoenvironmental and paleoclimate evolution in an alpine peat bog in southern Iberia: a geochemical approach
Authors: Mesa-Fernández Jose Manuel , García-Alix Antonio , Martínez-Ruiz Fancisca , Rodrigo-Gámiz Marta , Jiménez-Moreno Gonzalo , Jiménez-Espejo Francisco J. , López-Avilés Alejandro , Anderson R. Scott
Published: March 2022

Alpine lakes and peat bog from Sierra Nevada mountains in southern of Iberia are excellent paleoarchives since ecosystems are especially sensitive to climate variability and have been unaltered by humans until very recently. The Borreguil de la Virgen is a north-faced peat bog (BdlV; 37° 03′ 15″N, 3° 22′ 40″ W) located at 2945 m above sea level in a depression formed during the glacial retreat. A sedimentary record of 169 cm length has been analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) to obtain major and trace elemental composition, respectively. Different geochemical proxies have been used to reconstruct the paleoenvironmental evolution in the BdlV during the Holocene. Rb/Al, Zr/Al and Ca/Al have been used as detrital proxies while Mo/Al and U/Al have been used has oxygenation proxies. The Rb/Al ratio showed the highest values between 8.5 and 5.5 cal ka BP suggesting enhanced runoff related to enhanced humid conditions. This period is also characterized by the highest sedimentation rates and high values of U/Al ratio. Pervasive high runoff input during this interval was interrupted by two periods of reduced values of Rb/Al ratio between 8 and 7.5 cal ka BP and around 7.2 cal ka BP. More arid and/or colder conditions could have reduced the precipitation, explaining the decrease in runoff. After 5.5 cal ka BP the Rb/Al depicted a decreasing trend, suggesting less humid conditions and an aridification trend. At 5.5 cal ka BP the Zr/Al ratio also increased, which suggests the onset of the Saharan eolian dust export as result of the African Humid Period demise. Between 5.3 and 3.6 cal ka BP a major environmental change occurred involving the drying of the wetland, which promoted increases in the Mo/Al ratio due to the less oxic conditions and in the Ca/Al ratio since the Ca dissolved in water precipitated. This environmental change is followed by a period of low sedimentation rate between 3.6 and 1 cal ka BP which precludes us to make any accurate interpretation. The comparison between elemental ratios from BdlV with other nearby lake and bog records from Sierra Nevada highlight that the peat bogs are more prone to have enrichments in some elements when sedimentary conditions change, thus showing a higher local influence.