bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameter calibration and evaluation of the WRF-Hydro model within a semi-arid river basin
Authors: Serrano Barragan Jocelyn , Pedrozo Acuña Adrián
Published: March 2022

Heavy rainfall events and their consequent floods are of growing concern due to the significant damage to infrastructure and often fatalities. The necessity of producing high resolution spatiotemporal hydrometeorological information such as precipitation, streamflow, and soil mositure, for flood forecasting, is of most importance for emergency planning and decision making, and water managment. In this study, we conduct streamflow simulations for ten rainfall-runoff events that ocurred within a semi-arid river basin in northwestern México, using the WRF-hydro modeling system. Four primary parameters are tested for model calibration: runoff infiltration parameter REFKDT, surface retention depth RETDEPRT (scaled by the parameter RETDEPRTFAC), overland flow roughness parameter OVROUGHRT (scaled by the parameter OVROUGHRTFAC) and channel Manning roughness MannN. Parameter calibration is performed  applying a stepwise manual calibration method to two sub-basins and over two rainfall-runoff events, therefore, other events are used for evaluating model performance and asessmente of parameter transferability to other neighboring sub-basins in the study area. The Nash-Sutcliffe efficency, NSE, and the root mean squared error RMSE, RMSE-observations standard deviation ratio RSR and percent bias PBIAS are the statistical metrics chosen for parameter calibration and evaluation performance. Overall, model performance for streamflow simulation substantially improved after parameter calibration, obtaining an RMSE reduction of 58%, and  NSE value  of 0.466 after calibration. Although model was capable of reproducing observed hydrographs in terms of temporal distribution of streamflow, major errors are present in terms of reproducing the water balance in the basin. This is mostly observed when evaluating events that ocurred early in the wet season, when unsaturated soil conditions are still present. Results also indicate a poor parameter transferability, from calibrated parameters of sub-basin to other neighboring sub-basins. This was evidente for the majority of events evalauted, and those in which precipitation was not accurately depicted.
Probing coronal magnetic fields using high fidelity spectro-polarimetric low radio frequency observations of the Sun using the Murchison Widefield Array
Authors: Kansabanik Devojyoti , Oberoi Divya , Mondal Surajit
Published: March 2022

Magnetic field measurements at middle and higher coronal heights are challenging using conventional techniques with observations at visible or extreme ultra-violet wavelengths. Low radio frequencies are ideal for probing magnetic fields at higher coronal heights. Polarization properties of solar radio emissions are known to be a rich source of information about the emission mechanisms and magnetic fields of the corona. Nonetheless, largely due to technical challenges, precise polarimetric solar observations at low radio frequencies have remained challenging. The degree of polarization of solar radio emission varies dramatically over time, frequency, and also in morphology, depending on the emission mechanism. The radio bursts show a moderate to a high degree of circular polarization, while the quiet sun thermal emissions show a very low degree of circular polarization (<1%). Once feasible, detection of this very low circular polarisation from quiet Sun thermal emission will be an important tool to measure the quiet Sun coronal magnetic field. Simultaneous measurements of linear and circular polarisation from active emissions are important to understand the quasi-longitudinal and quasi-transverse propagation and will be a direct probe of the magnetic field geometry. According to the conventional views, linear polarization the low-frequency solar emission is expected to be wiped out due to large differential Faraday rotation. Hence, the few polarization studies of the low-frequency Sun in the past many decades have concentrated on measuring only the circular polarization. Nonetheless, we will show a few examples of convincing detections of linearly polarized emission from a variety of active solar emissions using observations from the Murchison Widefield Array (MWA). Perhaps the most rewarding, and also challenging, will be the polarimetric observations of faint gyrosynchrotron or thermal emission from the coronal mass ejection (CME) plasma, which will allow us to model the CME plasma parameters unambiguously at higher coronal heights. We have recently developed state-of-the-art polarization calibration and imaging pipeline for snapshot spectro-polarimetric solar imaging to enable the studies enumerated above and more. Here we summarise its current status and showcase some early science results which challenge the conventional wisdom and open a new window of the polarimetric study of the low-frequency radio Sun. While this pipeline is optimized for the MWA, a Square Kilometer Array (SKA) precursor, it can be adapted for the future SKA-Low and other future solar arrays in a straight forward manner.
Ammonium sensitivity of biological nitrogen fixation by anaerobic diazotrophs in cultures and benthic marine sediments.
Authors: Darnajoux Romain , Reji Linta , Zhang Xinrei , Luxem Katja , Zhang Xinning
Published: March 2022

Biological nitrogen fixation (BNF) is a critical process for the N budget and productivity of marine ecosystems. Nitrogen-fixing organisms typically turn off BNF when less metabolically costly N sources, like ammonium (NH4+), are available. Yet, several studies have reported BNF in benthic marine sediments despite high porewater NH4+ concentrations (10-1,500 µM). These activities were generally linked to anaerobic sulfate-reducing bacteria (SRB) and fermenting firmicutes.

To better understand the regulation and importance of benthic marine BNF, we evaluate the sensitivity of BNF to NH4+ in benthic diazotrophs using incubations of increasing complexity. We conduct our experiment with cultures of model anaerobic diazotrophs (sulfate-reducer Desulfovibrio vulgaris var. Hildenborough, fermenter Clostridium pasteurianum strain W5), sulfate-reducing sediment enrichment cultures, and slurry incubations of sediments from three Northeastern salt marshes (USA).

All our samples demonstrate high sensitivity to external NH4+. BNF is inhibited by NH4+ beyond an apparent threshold [NH4+] of 2 µM in liquid cultures and 9 µM in sediment slurries. Consistent with other studies, we find SRB-like nitrogenase (nifH) gene and transcripts are prevalent in sediments. We compare our inhibition threshold value with a survey of porewater NH4+ data from diverse sediments, suggesting the confinement of benthic BNF to surficial sediments.

Variations in the timing to onset BNF inhibition, NH4+ uptake rate, and sediment composition and biophysics could affect measurements of the apparent sensitivity of benthic BNF to NH4+. We propose a simple model based on NH4+ transporter affinity as a fundamental mechanistic constraint on NH4+ control of BNF to improve biogeochemical models of N cycling.
Understanding responses of summer continental daily temperature variance to perturbations in the land surface evaporative resistance 
Authors: Kong Wenwen , A. McKinnon Karen , R. Simpson Isla , M. Laguë Marysa
Published: March 2022

Understanding the roles of land surface conditions and atmospheric circulation on continental daily temperature variance is key to improving predictions of temperature extremes. Evaporative resistance (rs, hereafter), a function of the land cover type, reflects the ease with which water can be evaporated or transpired and is a strong control on land-atmosphere interactions. This study explores the effects of rs perturbations on summer daily temperature variance using the Simple Land Interface Model (SLIM) by mimicking a global land cover conversion from forest (high rs) to crop/grassland (low rs). Decreasing rs causes a global cooling. The cooling is larger in wetter areas and weaker in drier areas, and primarily result from perturbations in shortwave radiation (SW) and latent heat flux (LH). Decreasing rs enhances cloud cover due to greater land surface evaporation, thus reduces SW over most land areas. Wetter areas experience strong evaporative cooling, while drier areas become more moisture-limited when rs decreases, thus experience relatively less cooling. Thermal advection further shapes the temperature response by dampening the combined impacts of SW and LH. Temperature variance increases in drier areas and decreases in wetter areas as rs decreases. The temperature variance changes can be largely explained from changes in the combined variance of SW and LH, including an important contribution of changes in the covariance of SW and LH. In contrast to changes in the mean, changes in thermal advection variance amplify the changes in temperature variance predicted from the surface energy balance alone, particularly in the Northern Hemisphere mid-latitudes.
InSAR phase unwrapping using Graph neural networks 
Authors: Srivastava Anshita , Tiwari Ashutosh , Narayan Avadh Bihari , Dikshit Onkar
Published: March 2022

Advancements in processing strategies of time series interferometric synthetic aperture radar (InSAR) has resulted in improved deformation monitoring and DEM generation. Both of the applications use phase unwrapping, which involves finding and adding the unknown correct number of phase cycles to the wrapped phase. It is an inverse process of recovering the absolute phase from the wrapped phase, and the objective is to remove the 2π-multiple ambiguity. Ideally, it could be achieved by addition or subtraction of 2π at each pixel depending on the phase difference between the neighboring pixels. The problem appears effortless but brings challenges due to noise and inconsistencies. The conventional methods require improvements in terms of accurately estimating the unknown number of phase cycles and dealing with phase jumps. Recently, deep learning methods have been used extensively in the domain of remote sensing to solve complex image processing problems such as object detection and localization, image classification, etc. Since all the pixels in a stack of interferograms are not used in unwrapping, and the pixels used are scattered irregularly, modeling the unwrapping problem as an image classification problem is infeasible. In this work, we deploy Graph Neural Networks (GNNs), a class of deep learning methods designed to infer information from input graphs to solve the unwrapping problem. Phase unwrapping can be posed as a node classification problem using GNN, where each pixel is treated as a node. The method is aimed to exploit the capability of GNNs in correctly predicting the phase count of each pixel. The proposed work aims to improve the computational efficiency and accuracy of the unwrapping process, resulting in reliable estimation of displacement.
Characterization of organic aerosols by online CI-Orbitrap MS: Laboratory studies of biogenic SOA formation and size-dependent aerosol chemistry
Authors: Douverne Marcel , Böckmann Maximilian , Thomsen Ditte , Riva Matthieu , Perrier Sebastien , George Christian , Glasius Marianne , Hoffmann Thorsten
Published: March 2022

Atmospheric aerosols are an important part of Earth’s climate system. Further, they have great influence on air quality and human health. Secondary organic aerosols (SOA) generated from the oxidation of volatile biogenic precursors are an important contributor to the global aerosol budget. Therefore, understanding new particle formation and their subsequent growth is critical for our ability to predict the atmospheric aerosol composition and global climate change.

The coupling of a chemical ionization source with an Orbitrap mass spectrometer provides soft ionization and a high mass resolution for the on-line measurements of laboratory-generated SOA. Through heating of the aerosol, it is possible to measure both the gas phase and the vaporized particle phase. We use this technique to compare the chemical composition of particles produced from the oxidation of -pinene and -carene. Although exhibiting a very similar chemical structure, they differ greatly in their resulting SOA, in terms of particle size and number concentration when oxidized with ozone in smog-chamber experiments.  

These differences lie in their abilities to form characteristic SOA precursors, which depending on their chemical structure, promote either new particle formation or the growth of existing ones. The extremely low volatile organic compounds (ELVOCs) required for these processes are generally believed to be formed by gas phase chemistry. However, newly formed particles provide a unique nanoscale chemical environment that affects chemical reactions in the condensed phase and heterogeneous reactions on their surface, making them a potential source of ELVOCs as well. The increasing pressure inside the particles with decreasing diameter (Laplace pressure) favors bond-forming reactions. The lower viscosity in nanometer-sized particles further promotes reactions within the particle and increases reactivity at the particle surface such as heterogeneous oxidation. We show the particle size-dependent heterogeneous oxidation in a model system and ongoing work on other size-dependent reactions.
Projected Climate Change Indices over Central Europe Using Dynamically Downscaled CMIP6 Models
Authors: Dhib Saoussen , Halenka Tomas
Published: March 2022

Reliable climate projections foremost for temperature and precipitation are essential for countries adaptation and mitigation planning. The newest ensembles of climate models, used to construct projections of future climate, is CMIP6. This study will use CMIP6 regional climate model daily data from the portal of World Climate Research Program (WCRP) Coordinated Regional Downscaling Experiment (CORDEX). The main goal of this study is to estimate changes in climate indices for temperature (T) and precipitation (P) in Central Europe. Three models are selected (MIROC6, MRI-ESM2-0 and TaiESM1(AS-RCEC)) for three scenarios (SSP 245, SSP 370 and SSP 585). We use a baseline period of 1991-2010 and two future periods: 2031-50 (near future) and 2081-2100 (far future). Three temperature indices were considered: (i) number of frost days with minimal air T under 0 °C, (ii) number of ice days with maximal T below 0 °C and (iii) tropical nights (TN) index when minimal T exceed 20°C. Five precipitation indices were chosen to estimate climate change: (i) yearly mean precipitation, (ii) Simple daily intensity, (iii) number of extreme days with more than 20 mm/day, (vi) Consecutive dry and (v) wet days.

The study of the three model's ensemble concludes, a decrease by more than 30 % and 50 % in the freezing days (frost and ice) respectively for near and far future by SSP 585, the number of tropical nights is multiplied by 6 to 9 times foremost for South Germany and Austria. Regarding precipitation parameter, the annual maximum precipitation will increase by more than 100 mm/year with a slightly added rainfall amount (0.4 mm/day) for of SD index. Extreme rainy days rise by about 30 and 50 days by SSP 585 scenario respectively during the near and far future. The analysis of the wet/dry indices showed a slight increase foremost for the dry period length and the number of CDD period. A natural progression of this work is to analyze all the CMIP6 model's ensemble to set up more robust results.
Progressive veining during peridotite carbonation: insights from listvenites in Hole BT1B, Samail ophiolite (Oman)
Authors: Menzel Manuel D. , Urai Janos L. , Ukar Estibalitz , Decrausaz Thierry , Godard Marguerite
Published: March 2022

The reaction of serpentinized peridotites with CO2-bearing fluids to listvenite (quartz-carbonate rocks) requires massive fluid flux and significant permeability despite increase in solid volume. Understanding the mechanic-hydraulic interplay and the conditions, mechanisms and structures that enhance or hamper progress of this reaction is key to estimate the scale of long-term carbon fluxes and reservoirs in mantle rocks and their potential for industrial CO2 removal by mineral carbonation. Here we present a detailed microstructural analysis of listvenite and serpentinite samples from Hole BT1B of the Oman Drilling Project, which helps to understand the mechanisms and feedbacks during vein formation in this process [1]. The samples contain abundant magnesite veins in closely spaced, parallel sets and younger quartz-rich veins. These veins constitute large volumes of the listvenites, showing that fracturing and related advective fluid flow were integral to carbonation progress. Cross-cutting relationships suggest that antitaxial, zoned carbonate veins with elongated grains growing from a median zone towards the wall rock are among the earliest structures to form during carbonation of serpentinite. They show a bisymmetric chemical zoning of variable Ca and Fe contents with a systematic distribution of SiO2 and Fe-oxide inclusions; this and cross-cutting relations with Fe-oxides and Cr-spinel indicate that they record progress of reaction fronts during replacement of serpentine by carbonate in addition to dilatant vein growth. Euhedral terminations and growth textures of carbonate vein fill together with local dolomite precipitation and voids along the vein – wall rock interface suggest that these antitaxial veins acted as preferred fluid pathways allowing infiltration of CO2-rich fluids necessary for carbonation to progress. Fluid flow was probably further enabled by external tectonic stress, as indicated by the close spacing and subparallel alignment of these carbonate veins. As carbonation progressed, permeability was reduced during subsequent quartz veining and silica replacement of the matrix, but the scarcity of remnant serpentine in listvenite horizons indicates that penetration of CO2-rich fluid through the vein and matrix permeability network was sufficient for carbonation to proceed to completion.

[1] Menzel, et al., Solid Earth Discussions [preprint], https://doi.org/10.5194/se-2021-152, in review, 2022.

M.D.M. and J.L.U. acknowledge funding of DFG grants UR 64/20-1, UR 64/17-1.
Megathrust Seismicity Through the Lens of Explainable Artificial Intelligence
Authors: Graciosa Juan Carlos , Capitanio Fabio Antonio , Hargreaves Mitchell , Gollapalli Thyagarajulu , Zuhair Mohd
Published: March 2022

Understanding the controls on large magnitude seismicity occurrence remains an open challenge, yet a pressing one, for the exceptional hazard associated with earthquakes. Different parameters are proposed to exert control on the generation and propagation of megathrust earthquakes and untangling their complex interactions across scales remains challenging. Here, we use explainable artificial intelligence to unravel the interactions between different parameters and elucidate the underlying mechanisms. We use three types of datasets from a number of convergent margins: a) a catalogue of earthquake hypocentre and rupture, b) geophysical observations of subduction zones properties (e.g., gravity, bathymetric roughness, sediment thickness), and c) the distribution of stress within the slab due to slab pull calculated from flexure models. These constitute the three types of nodes in the input layer of a Fully Connected Network (FCN) trained to classify earthquake magnitude embedding the state of the system (b), the driving mechanism (c) and the resulting seismicity (a). We then analyse the trained network using Layer-wise Relevance Propagation (LRP) to determine the relative weights of the input nodes, providing relevant constraints on the mechanisms that dominate the seismicity in a region, their scale and likelihood.
Assessing the vulnerability of Norwegian forested landscapes to extreme wind speeds using the ForestGales model
Authors: Merlin Morgane , Zubkov Peter , Sunde Kathrin , Cattaneo Nicolas , Solberg Svein , Astrup Rasmus
Published: March 2022

In Europe, more than half of all the damages to forest by volume results from windstorms. In Norway, forests cover more than a third of the country’s land surface, and are important economically, culturally, and socially. Storm damage can have a range of consequences for the forestry industry and society including dangerous forest operations, reduced wood quality, reduced timber prices, electric outages, and increased risk for bark beetle outbreaks. It is crucial for all the actors in the forestry sector to understand wind damage. The recent storm of November 19th, 2021 highlighted this need and provided a unique opportunity to assess the research tools at our disposal to model wind damage risk in Norwegian forests.

One of these tools is the model ForestGales developed by the UK Forest commission to predict critical wind speeds for damage in a forest stand. The critical wind speed is a common measure of a tree's susceptibility to wind damage, defined as the wind speed that would cause tree failure due to wind, either by uprooting or breakage of the trunk at 1.3 m high. Used together with models describing the extreme wind speed distribution over a region, probabilities of wind damage can be drawn at the individual tree or forest stand level. The ForestGales model was modified to suit Norwegian conditions using the current available data and applied to two different situations:

Trees along powerlines. Tree failure can lead to powerline failure with potentially severe economic and social consequences. In this context, the ForestGales model could provide a tool to identify the risk trees and adapt management accordingly. We used the model on several sites along powerlines in the southern Norway and assessed its efficiency in predicting tree falls between summer 2020 and summer 2021, without any major storm events.

the Norwegian forest resource map SR16. The 16 x 16 m map product contains information relative to tree species, height, volume and biomass and is useful in large-scale analyses of the forest resources in the country. Using ForestGales on the SR16 map product would enable us to assess the fine-scale risk of wind damage over the entire country and inspect the impacts of changed forest structure following climate change and/or changes in forest management on the forest vulnerability to wind damage. The mapped damage from the storm of November 19th, 2021 will provide a unique opportunity to apply and test the validity and accuracy of the ForestGales model in Norway after a storm.
Local energy release by extreme vertical drafts in stratified geophysical flows
Authors: Foldes Raffaello , Cerri Silvio Sergio , Marino Raffaele , Feraco Fabio , Camporeale Enrico
Published: March 2022

Investigating energy injection mechanisms in stratified turbulent flows is critical to understand the multi-scale dynamics of the atmosphere and the oceans. Geophysical fluids are characterized by anisotropy, supporting the propagation of gravity waves. Classical paradigms of homogeneous isotropic turbulence may therefore not apply, the energy transfer in these frameworks being determined by the interplay of waves and turbulence as well as by the presence of structures emerging intermittently in space and time. In particular, it has been observed that stably stratified fluids can develop large-scale intermittent events in the form of extreme vertical velocity drafts, in a specific range of Froude numbers ([1]). These events were found to be associated with the enhancement of small-scale intermittency ([2]) and local dissipation ([3]). Here we verify the possibility that such extreme vertical drafts may release energy to the flow, affecting its overall dynamics and energetics. The analysis presented consists in the implementation of a space-filtering technique ([4]) applied to three-dimensional direct numerical simulations of the Boussinesq equations.

The strength of this approach relies on dealing with quantities (referred to as “sub-grid terms”) which are a reliable proxies of the classical Fourier flux terms but defined locally in the physical space, allowing for a scale analysis of the energy transfer at specific location of the domain flow. By investigating the correlation between values of the sub-grid terms and the presence of the extreme values of the vertical velocity, we found an increase in the energy transfer at intermediate scales that is likely to be associated with the development of vertical drafts in the flow. In the range of the governing parameters (namely the Froude and the Reynolds numbers) in which the extreme vertical drafts are detected in stratified turbulent flows, enhancement of the coupling between kinetic and potential energy modes is also observed, feeding in turn the scale-to-scale potential energy transfer.

 

[1] Feraco et al., EPL, 2018

[2] Feraco et al., EPL, 2021

[3] Marino et al., PRF, in review

[4] Camporeale et al., PRL, 2018
The Horizontal Slab Beneath East Asia and Its Subdued Surface Dynamic Response
Authors: Zhang Bo , liu Shaofeng , Ma Pengfei , Gurnis Michael
Published: March 2022

The kinematics of plate tectonics, deformation, and dynamic topography are strong indicators of coupling between plates and the mantle. East Asia is characterized by the presence of an unusually large horizontal slab that lies within the mantle transition zone. How this feature evolved and is linked to plate tectonics, deformation, and topography is poorly understood. Here, we show four-dimensional geodynamic modeling results constrained by a new deforming plate reconstruction that fits mantle architecture inferred from seismic tomography. We find that the subducted western Pacific slab was progressively torn by the Philippine Sea plate rotating clockwise during the Miocene and that northwestward mantle flow contributed to shaping the horizontal slab during subduction, leading to dynamic subsidence along the East Asia margin. The rather subdued change in dynamic topography, predicted from those models that fit the horizontal slab in the mantle, is consistent with the variation in residual topography, recorded in the stratigraphy, within only about +/- 200 m over the last 50 Myr during a period of no large marine inundation or retreat. The tectonics and topography of East Asia strongly contrast with those of Southeast Asia and are reflective of slabs ephemerally stagnating in the mantle below East Asia while avalanching into the lower mantle below Southeast Asia.
Water Mass Transformation in the Antarctic shelf
Authors: Boeira Dias Fabio , Uotila Petteri , Galton-Fenzi Ben , Ritcher Ole , Rintoul Steve , Pellichero Violaine , Nie Yafei
Published: March 2022

Antarctic Bottom Water (AABW) forms around Antarctica, sinks to the ocean’s abyss and fills more than 30% of the ocean’s volume. The formation of AABW includes mixing of distinct water masses, such as High Salinity Shelf Water (HSSW), Ice Shelf Water (ISW) and Circumpolar Deep Water on the continental shelf. Despite its climatic importance, the mechanisms of AABW formation are poorly known due to the lack of observations and the inability of climate models to simulate those mechanisms. We applied the Water Mass Transformation (WMT) framework in density space to simulations from a circumpolar ocean-ice shelf model (WAOM, with horizontal resolution ranging from 10 to 2 km) to understand the role of surface fluxes and oceanic processes to water mass formation and mixing on the Antarctic continental shelf, including the ice shelf cavities. The salt budget dominates the water mass transformation rates, with only secondary contribution from the heat budget. The buoyancy gain at relatively light density classes (27.2 < σΘ < 27.5 kg/m3) is dominated by basal melting. At heavier densities (σΘ > 27.5), salt input associated with sea-ice growth in coastal polynyas drives buoyancy loss. The formation of HSSW occurs via diffusion of the surface fluxes, but it is advected towards the cavities of large ice shelves (e.g., Ross, Ronne-Filchner), where it interacts with ice shelf through melting and refreezing and forms ISW. The sensibility of those mechanisms to the model horizontal resolution was evaluated. The basal melting and associated buoyancy gain rates largely decrease with increased resolution, while buoyancy loss associated with coastal polynyas are less sensible to resolution as surface fluxes are estimated from sea ice concentration observations. These results highlight the importance of high resolution to accurately simulate AABW formation, where mixing processes occurring below ice shelf cavities play an important role in WMT.
Protection of peri-urban groundwater catchments: a multi-tracer approach for the identification of urban pollution sources
Authors: Balzani Laura , Orban Philippe , Brouyère Serge
Published: March 2022

Groundwater catchment located in peri-urban areas may be impacted by many pollutants coming from different types of point or diffuse sources such as accidental spills, continuous hidden leaks in drainage networks, old landfills, treated/untreated wastewater and watercourses.

In the scope of the CASPER project, a new methodological approach has been developed based on field survey and interpretation of the collected data in order to distinguish between the different sources of contamination and mixtures of pollutants. First, the groundwater catchment area corresponding to the land surface perimeter in which abstracted groundwater is recharged is determined and characterised in hydrogeological terms. The possible sources of pollution are identified. In a second step, a groundwater and surface water monitoring survey is established, and water samples are collected focusing on a combination of physicochemical parameters and set of various hydrochemical indicators. In particular, different stable isotopes are considered. The NO3- and B stable isotopes are used to distinguish between inputs linked to urban effluents, agricultural fertilisers and manure. Stable isotopes of SO42- are used to distinguish between sulphide minerals oxidation, sulphur-carbon compounds mineralisation, lixiviation and human pollution. Moreover, the occurrence of specific molecules like pharmaceutical and lifestyle products (carbamazepine, caffeine, etc.) are used as effective tracers of anthropogenic contamination. Microbiological analyses are also undertaken to identify microbial populations associated with specific sources of pollution or specific biochemical reactions occurring in soil and groundwater. The resulting hydrochemical dataset is then processed using multivariate and clustering analyses.

In this context, the objective here is to describe the methodological approach developed for source identification and to illustrate this using a case study corresponding to a groundwater catchment is a chalk aquifer in Western Belgium.
Teleconnections and a holistic Earth Systems approach to a retreating Alpine glacier
Authors: Le Heron Dan , Bristow Charlie , Davies Bethan , Grasemann Bernhard , Kettler Christoph , Schöpfer Martin
Published: March 2022

The Gepatschferner in the Öztal Alps is Austria’s second largest glacier and is the subject of a monitoring campaign from 2019 onwards which was initially focussed on sedimentology and geomorphology of the forefield. Emphasis was placed on the styles and rates of sediment cannibalisation, with implications for transcription of the evidence into the deep time sedimentary record. This included the mapping of flutes, crag and tail structures, roches moutonées, fluvial sediments, till and rockfall deposits in the proglacial area. Their evolution over time is documented by repeated fieldwork and drone surveys. However, cognizant of the complexity of the subglacial environment (deforming bed areas, rigid bed areas and shifting meltwater systems) our work has expanded to ground-penetrating radar (GPR) surveys, enabling us to map subglacial conduits, englacial channels, and glacier structure. This structure involves the mapping of foliation, folds and fractures in the glacier, supported by field measurements. Repeated survey of both GPR and drones allows the 4D evolution of surficial glacier drainage, elevation, and forefield to be characterised. This work thus encompasses sedimentology, geomorphology, structural glaciology and bedrock geology. We argue that investigating the temporal and spatial landsystem-scale interactions between cryosphere (glacier and its structure), hydrosphere (meltwater pathways), and lithosphere (geomorphology, bedrock geology, sedimentology) will lead to breakthrough interpretations. These will include (i) controls on the evolution of the meltwater system, (ii) controls on the genesis of subglacial bedforms, (iii) the relationship between geology, geomorphology and glacier structure. Repeated, iterative surveys allow us to explore the teleconnections between cryosphere, hydrosphere and lithosphere, and their predictive capacity.
Properties of quasi-periodical emission of electromagnetic ion cyclotron waves
Authors: Shahid Muhammad , Bashir M. Fraz , Artemyev Anton , Zhang Xiaojia , Angelopoulos Vassilis , Murtaza Ghulam
Published: March 2022

Energetic electron scattering by electromagnetic ion cyclotron (EMIC) waves is one of the most effective mechanisms of electrons losses in the inner magnetosphere. Such resonant scattering has been traditionally considered as a controlling process for the dynamics of relativistic electron fluxes in the Earth’s radiation belts. EMIC wave generation is mainly associated with the ring current ion population injected from the plasma sheet. These ions are drifting westward and generate the most intense EMIC waves on the dusk flank. In this work, we consider an alternative mechanism of EMIC wave generation due to local plasma compression by strong ultra-low-frequency (ULF) waves that modulate a quasi-periodical ion anisotropy responsible for EMIC excitation. Using THEMIS spacecraft observations of simultaneous EMIC waves and compressional ULF waves, we investigate the statistical properties of such quasi-periodic EMIC emission. We show spatial distributions of ULF-modulated EMIC waves, statistics of their amplitudes and typical frequencies. We also discuss the associated measurements of ULF-modulated hot ion populations responsible for EMIC wave generation.
Rift to drift evolution and crustal structure of the Central Atlantic: the Sidi Ifni-Nova Scotia conjugate margins
Authors: Gouiza Mohamed
Published: March 2022

The breakup of Pangaea in Early Mesozoic times initiated first in the Central Atlantic region, where Triassic to Early Jurassic lithosphere extension led to continental breakup and oceanic accretion. The Central Atlantic rifted margins of NW Africa and eastern North America exhibit complex along-strike variations in structural configuration, crustal geometries, and magmatic budget at breakup. Quantifying these lateral changes is essential to understand the tectonic and geodynamic processes that dominated rifting and continental breakup. The existing seismic refraction lines along the African side and its American conjugate provide good constraints on the 2D crustal architecture of several Central Atlantic margins. However, they are insufficient to quantify the ambiguous lateral variations.

This work examines the central segment of the Moroccan Atlantic margin, which is named here the Sidi Ifni-Tan Tan margin. Using 2D seismic reflection and well data, we quantify the stratigraphic and structural architecture of the margin. We then use this to constrain 2D and 3D gravity models, to predict crustal thickness and types. Ultimately, our results are integrated with previous findings from the conjugate Nova Scotia margin, on the Canadian side, to propose a rift to drift model for this segment of the Central Atlantic and discuss the tectonic processes that dominated rifting and decided the fate of continental breakup.
Effects of multiple detachments in thin-skinned fold and thrust belts: insights from analogue modelling
Authors: Copot Bianca , Tamas Dan M. , Tamas Alexandra , Krezsek Csaba , Schleder Zsolt , Lapadat Alexandru , Filipescu Sorin
Published: March 2022

Thin-skinned fold and thrust belts present exploration challenges in many places worldwide. The presence of multiple detachments in the stratigraphic sequence also adds to the complexity of such fold and thrust belts. This study aims to understand more about the effects of multiple detachments in thin-skinned fold and thrust belts through scaled analogue modelling experiments. Our main area of interest is Romania's prolific onshore hydrocarbon area, the foreland of the Eastern Carpathian Bend Zone. Here, one of the large uncertainties is if the Oligocene to lower Miocene strata experienced any shortening before salt deposition. If so, what would be the difference in the observed geometries?

Scaled sandbox models with layered brittle and ductile materials were used to gain critical insights into the structural evolution of this fold and thrust belt (ECBZ) and to reduce the above-mentioned uncertainties. The materials used in these experiments are: coloured dry quartz sand (for modelling brittle behaviour), silicone (for ductile behaviour of the salt), 200-300 μm glass microspheres and a mixture of silicone and granular materials (for the other detachment levels).

The experimental setup consists of a computerized deformation device that pulls a mobile plate at a constant rate beneath a fixed deformation box with one glass sidewall, one end of the box acting as a static buttress. Deformation monitoring has been achieved using top-view 3D digital image correlation techniques (DPIV- Digital Particle Image Velocimetry). The models were serially sectioned and photographed after post-experiment treatment (wetting and consolidation). The sections were used to build and interpret 3D digital models of the experiments.

Duplex structures mainly characterize the deformation in the sub-silicone. Some particular geometries observed in the sub-silicone (salt) sequence are buckle folds and lift-off folds. These mainly occur when the detachments within the sub-silicone mechanical stratigraphy consist of silicone/granular mixture. Although not traditionally interpreted and observed in the area, these results raise the possibility of alternative interpretations. The supra-silicone (salt) deformation is less complex, characterized by both fore- and backthrusts, most of them initiating as detachment folds, similar to what is seen in our area of interest.

Experimental results reduce exploration uncertainties by bringing more insights into the control and effects of multiple detachments on the structural development of fold and thrust belts. These modelling results also bring new possible interpretations in areas poorly constrained by seismic and well data.
The Role of Carbonates in Regulating Atmospheric CO2 on Earth-like Exoplanets
Authors: Hakim Kaustubh , Tian Meng , Bower Dan J. , Heng Kevin
Published: March 2022

Ocean chemistry plays a key role in the removal of CO2 from the atmosphere-ocean system in the form of carbonates that are eventually subducted to the mantle. Silicate weathering and CO2 dissolution dictate the steady-state ocean chemistry and thereby the carbonate-silicate cycle (inorganic carbon cycle). Data on stellar elemental abundances suggest a strong diversity in the bulk mineralogy of exoplanets. We study the role of weathering-derived divalent cations (Ca++, Mg++) on ocean pH and carbonate compensation depth (CCD) in exoplanet oceans. If CCD is too shallow, carbonates on the seafloor cannot be subducted to the mantle. We find that the presence of carbonates sets the upper bound on ocean pH and CO2 dissolution sets the lower bound on ocean pH. We show that CCD increases with increasing divalent cations supplied by weathering and decreases with CO2 dissolution. 
A Discrete Elements Modelling Framework for the Parametric Study of Landslides in Low Gravity Environments
Authors: Penasa Luca , Lucchetti Alice , Pozzobon Riccardo , Munaretto Giovanni , Pajola Maurizio , Rossi Costanza
Published: March 2022

Landslides are almost ubiquitous in the Solar System, with rockfall and avalanches that are observed also on other terrestrial bodies, such as the Moon (Bart, 2007; Xiao et al., 2013), Mars (Crosta et al., 2018; Lucchitta, 1987) and Mercury (Malin & Dzurisin, 1978). Landslides and mass movements have been observed also on planetary bodies characterized by extremely low gravity, as for example asteroids’ surfaces of Vesta and Ceres (Otto et al., 2013; Schmidt et al., 2017). The behaviour of mass movements on these bodies is poorly studied due to the difficulties of recreating low-gravity experimental conditions or identifying satisfactory analogues for the involved materials. In fact, the overall dimensions and morphology of the resulting deposits (area, width and length) are often the only features that can be studied and compared between different sites or planetary bodies, due to the limitations in DEMs resolution and suitable imagery.  In particular, plots of the H/L ratio (drop height/runout length) provide a proxy for the average friction coefficient and have been the subject of many comparative investigations.

With the aim of providing a more consistent picture of the possible outcomes of landslides and other mass movements we hereby describe a fully parametric numerical framework based on ESyS-Particle software  (Abe et al., 2004; Tancredi et al., 2012), which has been specifically designed to explore the outcomes of fragmenting grain flow under different model assumptions. The framework has been designed to leverage modern distributed computing technologies to increase the number of simulations that can be executed in parallel, and to maximize the usage of already-available computing hardware. Preliminary results and the limitations are also presented and discussed.

This framework will support the parametrization of numerical models for the upcoming observations of mass-movements of the future JUICE-JANUS camera observations on Jupiter Icy Moons.

Acknowledgements: The activity has been realized under the ASI-INAF contract 2018-25-HH.0.
Quantifying the importance of vegetation in water fluxes partitioning over Mediterranean mountain areas: a study case in Cardeña-Montoro Natural Park (Spain)
Authors: Andreu Ana , Pimentel Rafael , Torralbo Pedro , Aparicio Javier , González-Dugo María P. , Polo María José
Published: March 2022

Mediterranean mountain areas are hotspots when evaluating vulnerability towards global warming. Future hydro-climatic scenarios present a probable situation of high alteration of these systems, mainly conditioned by an increase of extreme events frequency (e.g., heatwaves and droughts). Dehesas are one of these characteristic landscapes. They result from the co-evolution of autochthonous ecosystems and human settlement in a sustainable balance, with high relevance from the environmental (biodiversity) and socioeconomic (livestock farming, including the Iberian pork food industry) view. They have a complex vegetation cover structure formed by isolated trees, mainly holm oak, cork oak, and oak, Mediterranean shrubs, and pastures, with specific phenological cycles. This complexity conditions the partitioning of water fluxes, shifting their importance along the year. 

This work proposes to quantify the actual role of the vegetation in the water fluxes partitioning over mountain Mediterranean areas. Specifically, this study is conducted in the Martin Gonzalo watershed upstream of the Martin Gonzalo dam, located within the Cardeña-Montoro Natural Park (southern Spain). The vegetation role is assessed by comparing three different hydrological model simulations conducted using the distributed and physically-based hydrological model WiMMed (Watershed Integrated Model for Mediterranean Areas): i) non-vegetation, in which no vegetation is included in the modelling; ii) static vegetation, in which vegetation is defined in the model using the official land cover maps from the regional authorities; and iii) dynamical vegetation, in which vegetation information is provided by a dynamical spectral mixture analysis using Sentinel-2. All water fluxes in the water balance are quantified and compared between the three simulations. Results highlight, on the one hand, the key role of vegetation in controlling water partitioning and, on the other hand, the importance of considering the yearly phenological changes to model water partitioning accurately.  

 

 

This work has been funded by project SIERRA Seguimiento hIdrológico de la vEgetación en montaña mediteRránea mediante fusión de sensores Remotos en Andalucía, with the economic collaboration of the European Funding for Rural Development (FEDER) and the Office for Economy, Knowledge, Enterprises and University of the Andalusian Regional Government.
Towards the improvement of EOP prediction: first results of the 2nd EOP PCC
Authors: Modiri Sadegh , Thaller Daniela , Belda Santiago , Guessoum Sonia , Ferrandiz Jose M , Raut Shrishail , Dhar Sujata , Heinkelmann Robert , Schuh Harald
Published: March 2022

The real-time Earth orientation parameters (EOP) estimation is needed for many applications, including precise tracking and navigation of interplanetary spacecraft, climate forecasting, and disaster prevention. However, the complexity and time-consuming data processing always lead to time delays. Accordingly, several methods were developed and applied for the EOP prediction. However, the accuracy of EOP prediction is still not satisfactory even for prediction of just a few days in the future. Therefore, new methods or a combination of the existing approaches can be investigated to improve the predicted EOP. To assess the various EOP prediction capabilities, the international Earth rotation and reference systems service (IERS) established the working group on the 2nd Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC).
Our EOP prediction team provides the full set of EOP predictions weekly for one year ahead. The SSA+Copula method and the empirical free core nutation (FCN) model (named B16) are used for Earth rotation parameters and celestial pole offsets (CPO) prediction, respectively. 
Our preliminary results illustrate an improvement in EOP prediction compared to the current EOP prediction methods, especially on CPO. Additionally, the comparison with other method results indicates that the proposed techniques can efficiently and precisely predict the EOP at different terms (short, mid, and long term).