bluuebunny/crossref_metadata_2025 huggingface dataset:
Capabilities for Aquifer Monitoring of long-term MHVSR Observations in Campo de Dalías (Almería, SE Spain)
Authors: García-Jerez Antonio , Seivane Helena , Navarro Manuel , Molina Luis
Published: March 2022

Preceding the seismic modelling of Campo de Dalías sedimentary basin by single-station ambient noise measurements, research focused on the reliability of the methodology employed, namely the microtremor horizontal-to-vertical spectral ratio (MHVSR), is conducted. It is known that MHVSR may present some dependence on weather and site-specific conditions as topographic effects, anthropogenic activities or the variability in the microtremor source distribution. In this context, the stationarity of MHVSR curves with their fundamental peaks below 1 Hz is studied after the installation of three long-term stations in rural sites and another one for a week in the urban area of El Ejido town.

The robustness of the MHVSR methodology is often assured by looking into the stationarity of mainly two peak parameters: frequency and amplitude. In this study, two new parameters are tested: the peak-width and the trough frequency. We have up to two years of microtremor and weather data that helped to track the variability of wind speed, atmospheric pressure, and temperature, as well as sea tide and aquifer levels compared to the peak shape of MHVSR curves.

Most weather variables only show short or punctual correlations with MHVSR parameters, which is the case of wind gusts above 10 m/s that totally blurred the MHVSR peak-shape for periods of a few days in the more poorly isolated station. The wind-speed time series collected in Campo de Dalías show high correlations with the total microtremor energy in the frequency band of secondary microseisms (0.3 - 1 Hz) with a clear seasonal behaviour. However, the MHVSR peaks studied in that band are uncorrelated with them. Our results show that the piezometric level maintains a moderate to high correlation with MHVSR peak-variability during a time span of 9 months. Campo de Dalías hosts a system of karst aquifers, which constitutes the main water supply for this semi-arid region. Modelling the groundwater flow in that kind of aquifers is a challenging field of research and monitoring it by means of investigation wells has a high cost. The results observed in this study widen the possibilities of MHVSR for being an aquifer-monitoring tool on time scales as short as a few days.
Optimized setup and long-term validation of anomaly detection methods for earthquake-related ionospheric-TEC (Total Electron Content) parameter over Italy and Mediterranean area
Authors: Colonna Roberto , Filizzola Carolina , Genzano Nicola , Lisi Mariano , Pergola Nicola , Tramutoli Valerio
Published: March 2022

Near the end of the last century and the beginning of the new, different types of geophysical parameters (components of the electromagnetic field in several frequency bands, thermal anomalies, radon exhalation from the ground, ionospheric parameters and more) have been proposed as indicators of variability potentially related to the earthquakes occurrence. During the last decade, thanks to the availability of historical satellite observations which has begun to be significantly large and thanks to the exponential growth of artificial intelligence techniques, many advances have been made on the study of the seismic-related anomalies detection observed from space.

In this work, the variations in Total Electron Content (TEC) parameter are investigated as indicator of the ionospheric status potentially affected by earthquake related phenomena. In-depth and systematic analysis of multi-year historical data series plays a key role in distinguishing between anomalous TEC variations and TEC changes associated with normal ionospheric behavior or non-terrestrial forcing phenomena (mainly dominated by solar cycles and activity).

In order to detect the differences between the two types of variation, we performed an optimal setting of the methodological inputs for the detection of seismically related anomalies in ionospheric-TEC using machine learning techniques and validating the findings on multiple long-term historical series (mostly nearly 20-year). The setting was optimized using techniques capable of combining multi-year time series of TEC satellite data and multi-year time series of seismic catalogues, simulating their behaviors in tens of thousands of possible combinations and classifying them according to criteria established a priori. Input setup and validation were done by investigating possible links between TEC anomalies and earthquake occurring over Italy and Mediterranean area. We will show and comment the results of both, optimal input setting and statistical correlation analyses consequently performed, and we will discuss the potential impact of these on future developments in this field.
Near-term prediction of the global carbon cycle using EC-Earth3-CC, the Carbon Cycle version of the EC-Earth3 Earth System Model
Authors: Tourigny Etienne , Bernardello Raffaele , Sicardi Valentina , Ortega Pablo , Ruprich Robert Yohan , Lapin Vladimir , Acosta Navarro Juan C. , Bilbao Roberto , Meier Arndt , Li Hongmei , Ilyina Tatiana
Published: March 2022

Anthropogenic CO2 emissions are associated with global warming in the late 20th century and beyond. Climate-carbon feedbacks will likely result in a higher airborne fraction of emitted CO2 in the future. However, the variability in atmospheric CO2 growth rate is largely controlled by natural variability and is poorly understood. This can interfere with the attribution  of slowing CO2 growth rates  to reducing emissions during the implementation of the Paris Agreement. There is thus a need to both improve our understanding of the processes controlling the global carbon cycle and establish a near-term prediction system of the climate and carbon cycle.

As part of the 4C (Carbon Cycle Interactions in the Current Century) project, the Barcelona Supercomputing Center is implementing a new system for near-term prediction of the climate and carbon cycle interactions using EC-Earth3-CC, the Carbon Cycle version of the EC-Earth3 Earth System Model. This new system is based on the existing operational climate prediction system developed by the BSC, contributing to the WMO Global Annual to Decadal Climate Update. EC-Earth3-CC comprises the IFS atmospheric model, the NEMO ocean model, the PISCES ocean biogeochemistry model, the LPJ-GUESS dynamic vegetation model, the TM5 global atmospheric transport model and the OASIS3 coupler. The system uses initial conditions from in-house ocean biogeochemical and land/vegetation reconstructions based on global atmospheric/ocean reanalyses. By performing retrospective decadal predictions of ocean and land carbon uptake we are able to evaluate the performance of the system in predicting CO2 fluxes and atmospheric CO2 concentrations.

We will present results from the latest concentration- and emission-driven retrospective predictions (or hindcasts) using our system, highlighting the skill and biases of the carbon fluxes and atmospheric CO2. We will also present future predictions for 2022 and beyond, a prototype for the operational system for prediction of future atmospheric CO2.
Regionalization of a Distributed Hydrology Model Using Random Forest
Authors: Pouryousefi-Markhali Siavash , Poulin Annie , Boucher Marie-Amélie
Published: March 2022

Distributed hydrology models are suitable tools for understanding the hydrological processes, which take place on heterogeneous media under ever-changing internal (e.g. land use change) and boundary conditions (e.g. climate change). The generally accepted practice for applying such models is to calibrate their parameters using observed data. Still in many locations, even in developed countries, observed data is lacking or unreliable. Regionalization is a way around this problem. In this research, we built a Random Forest (RF) model to regionalize the parameters of a distributed hydrology models (Hydrotel), which is the operational model at Quebec government. Using the RF model, the following three hypotheses were tested regarding the efficiency and spatio-temporal variability of the proposed regionalization technique: (1) A finer time-step adds more information to the calibrated parameters and therefore improves the efficiency of the regionalization method; (2) The parameters approximated by RF are spatially consistent and therefore transferrable across spatial scales (i.e. from lumped to sub-catchment to hydrological response units); (3) Using more spatially representative predictors (i.e. by refining the spatial resolution of CDs) to reflect heterogeneity of the catchment will improve the performance of regionalization at internal ungauged locations. All these hypotheses were tested on three groups of nested catchments at 3- and 24-hour time-steps. The results show that for simulations at sub-daily time-steps, the calculated loss of regionalization efficiency (with respect to calibration) is less than that of the 24-hour time-step (12% improvement). Approximating the parameters at different levels of spatial discretization demonstrates that the parameters are spatially consistent as the distribution of parameters and catchment descriptors are spatially correlated. Finally, we found a consistent improvement of simulations when we replace lumped with fully distributed parameters, for simulations with a 24-hour time step. This improvement in the efficiency is higher for catchments with a higher degree of spatial heterogeneity (up to 12%). However, no significant improvement in the efficiency of simulation from lumped to distributed parameters has been observed when the time-step of the simulation was reduced to 3-hour.
Global Distribution of Hydrogen Content in the Martian Subsurface as Seen by the FREND Neutron Telescope Onboard ExoMars TGO
Authors: Malakhov Alexey , Mitrofanov Igor , Sanin Anton , Litvak Maxim , Golovin Dmitry , Djachkova Maya , Lukyanov Nikita , Nikiforov Sergey , Anikin Artem , Lisov Denis
Published: March 2022

FREND telescope performs measurements of the Martian neutron flux since May 2018. Estimation of hydrogen content in the upper one meter of the regolith is possible based on these data. Because of the instrument’s collimator limiting its field of view, it is also possible to produce high spatial resolution maps, never achieved before on Mars. In this study we will show maps of water equivalent hydrogen distribution in the Martian equatorial region, along with description of all the techniques performed to build these maps from raw instrument measurements to water content estimation. Since FREND is an instrument of statistical nature, these maps are assessed to provide the range of their statistical error. Finally, we perform global analysis of these maps to locate most prominent water-rich areas, and an enhanced analysis to assess some of these areas individually.

This study is performed with support of Russian Science Foundation grant 19-72-10144.
CHENILLE: Coupled beHavior undErstaNdIng of fauLts: from the Laboratory to the fiEld
Authors: Bonnelye Audrey , Dick Pierre , Cotton Fabrice , Giese Rüdiger , Guglielmi Yves , Jougnot Damien , Henninges Jan , Kwiatek Grzegorz , Lüth Stefan
Published: March 2022

The understanding of the coupled thermo-hydro-mechanical behaviour of fault zones in naturally fractured reservoirs is essential both for fundamental and applied sciences and in particular for the safety assessment of radioactive waste disposal facilities. In this framework, an international research program callled CHENILLE was built to address key questions related to the impact of high temperatures (up to 150°C) on shear zones as well as fault reactivation processes in shale formations. The project includes a thermally controlled in situ fluid injection experiment on a strike-slip fault zone outcropping atIRSN’s Tournemire Underground Research Laboratory (URL) and a series of laboratory experiments to understand the chemical and structural evolution occurring within the fault zones during the thermal and hydraulic loading. The in situ experiment includes a heating system installed around an injection borehole will enable a precise and controlled incremental increase of the thermal load. The injection borehole will be equiped with a Step-Rate Injection Method for Fracture In-Situ Properties (SIMFIP) probe, in order to perform step pressure tests. The probe will not only measure the flow and pressure rate inside the injection borehole but also allow to monitor the borehole’s 3D deformation during the hydraulic and thermal loading steps. In addition, an array of seismicifferent sensors will be implemented around the injection area to measure the seismic and aseismic deformation induced either by thermal or by hydraulic loading. The seismic monitoring system is composed of Acoustic Emission (sensitive between 1kHz and 60kHz) enabling monitoring fracturing processes of sub-decimeter size. Furthermore, a fibre optic network will be installed in the heating boreholes to measure spatially temperature variationsvia Distributed Temperature Sensing technology in the investigation area. Active seismic surveys, using different source types, are scheduled before and after the experiment to determine the structural network but also to detect the appearance of new structures triggered from the hydro-thermal pressurization of the fault by tomography and reflection seismic methods. The overall goal of our work is to present the interaction between the different geophysical methods that we are using as well as some preliminary results. A first part is dedicated to the description of the fault zone through field and core samples observations as well as borehole to borehole correlation, whereas the second is dedicated to preliminary results on the thermal diffusion expected in the fault.
Promoting Primary Production? Using Remotely Sensed Data to Investigate Human Impacts on Primary Production at a Global Scale
Authors: Sillem Catherine , Prentice Colin
Published: March 2022

People are altering ecosystem form and function on a global scale through land use – changing the capacity for primary production, with consequences for the Earth System. Yet these changes are not uniform, and the interactions between population density and environmental conditions are not well established. Here we compare satellite-observed Fraction of Photosynthetically Active Radiation (FPAR) data from MODIS with a Potential Natural Vegetation (PNV) FPAR data set (Hengl, 2018), which was created using the random forest algorithm to predict vegetation properties in the absence of human alteration. Taking the average value per pixel from 2014–2017, a fixed-effects model was fitted with observed FPAR as the response variable, and predicted natural FPAR and its interactions with population density (www.worldpop.org) and biome type as the dependent variables. Population density was shown to reduce the slope of observed versus predicted FPAR, consistent with the hypothesis that the overall effect of human population density is to reduce FPAR when potential FPAR is high but to increase FPAR when potential FPAR is low. The effects differ across biomes. Maps of the difference between observed and PNV FPAR, and of the model residuals are generated to identify areas in which human activities may be promoting primary production. Whilst we limit our analysis to one of the most researched cultural variables (population density) and appreciate that our chosen data provide only a snapshot in time, with its own specific set of cultural and environmental conditions, we hope this analysis will provide a useful counterpoint to other work in unravelling human-environmental interactions at a global scale.

Hengl, T., Walsh, M. G., Sanderman, J., Wheeler, I., Harrison, S. P., & Prentice, I. C. (2018). Global mapping of potential natural vegetation: An assessment of machine learning algorithms for estimating land potential. PeerJ, 2018(8), 1–36. https://doi.org/10.7717/peerj.5457
Accelerated oceanic forcing in coupled ice sheet-ocean modelling
Authors: Zhou Qin , Zhao Chen , Gladstone Rupert , Hattermann Tore , Gwyther David , Galton-Fenzi Benjamin
Published: March 2022

Coupled ice sheet - ocean models are increasingly being developed and applied to important questions pertaining to processes at the Greenland and Antarctic Ice Sheet margins, and the wider implications of such processes. In particular, ice sheet - ocean interactions have a strong control on ice sheet stability and sea level contribution. One of the challenges of such coupled modelling activities is the timescale discrepancy between ice and ocean dynamics, which, combined with the high cost of ocean models, can limit the timeframe that can be modelled. Here we present an "accelerated oceanic forcing'' approach to the ocean side of the coupling, in which the rates of change passed from ice model to ocean model components are increased by a constant factor and the period for which the  ocean model is run is correspondingly decreased. The ice sheet change over a coupling interval is thus compressed into  a shorter period over which the ocean model is run, based on the assumption that the ocean response time frame is shorter than  the compressed run period. We demonstrate the viability of this approach in an idealised setup based on the Marine Ice Sheet-Ocean Model Intercomparison Project, using the open-source Framework for Ice Sheet-Ocean Coupling (FISOC) combining two different ocean models (FVCOM and ROMS) and the ice-sheet model Elmer/Ice. We also demonstrate that the mean cavity residence time computed from the stand-alone ocean simulations can guide the selection of a suitable enhanced forcing factor for the coupled simulations. 
Showcaves: A modern geo-conservation approach utilizing geo-ethics and heritage management principles through sustainable monitoring technology
Authors: Kontostavlos George , Vassilakis Emmanuel , Triantafyllou Maria , Konsolaki Aliki
Published: March 2022

The complexity of show caves and the problems arising through human interaction with them, require interdisciplinary approaches capable of synthesizing a range of parameters such as knowledge, methods and provided tools to promote geo-ethical thinking and geoscientists contribution for sustainable management. Show caves are tourist/commercial caves which have been accessible to the public with artificial lighting, shaped paths, guided tours, open hours and they are considered as heritage sites. The concept of heritage is a complex idea, controversial and culturally constructed, depending on the personal and collective background and experiences of the members of a society. Heritage is often artificially divided into natural and cultural, but regarding the “show caves” as entities, the boundaries are indistinguishable. Moreover, show caves suffer successive degradation for several interconnected reasons. This work analyzes proposals for compilation of protocols and general management that may involve educational institutes, management agencies, policy makers and stakeholders based on remotely monitored parameters and scientific data collection, for feeding assessment and evaluation tools. The main scope is to arouse a wider dialogue of the interested parts with the aim to form the basis for the creation of a European legislation for protecting these sensitive but also complex environments through geo-conservation and geo-ethics approaches.
Geodetic evidence for a significant component of shortening along the northern Caribbean strike-slip plate boundary in southern Haiti
Authors: Calais Eric , Symithe Steeve , Mercier de Lépinay Bernard
Published: March 2022

GPS measurements within the transform Caribbean–North American plate boundary in Hispaniola, Greater Antilles, with five additional years of data at continuous sites and additional campaign measurements, significantly improve the resulting velocities of earlier works. In a Caribbean-fixed frame, velocities at sites located along the island's southern coast are small (< 2 mm/yr), indicating that the offshore active faults mapped south of Haiti are currently slipping at very low rates. In the Southern Peninsula, velocities are oriented westward, parallel to the Enriquillo fault zone, consistent with strain accumulation on that left-lateral strike-slip fault. North of the Southern Peninsula, including the Gonâve island, velocities are consistently trending SW to WSW, oblique to the east-west direction of the plate boundary. This difference in velocity trend between the Southern Peninsula and areas to the north indicates regional shortening north of the southern Peninsula with an amplitude of 6-7 mm/yr of plate boundary-normal shortening. Geologic and high-resolution seismic data show that this shortening is likely taking place just at the northern coast of the Southern Peninsula, localized on a north-verging reverse fault system offshore the north coast of the Southern Peninsula of Haiti. This reverse fault system extends westward a similar fault system previously described on the southern edge of the Cul-de-Sac Plain, together delineating what we call the "Jérémie-Malpasse" reverse-fault system. This fault zone marks the boundary between the Caribbean Large Igneous Province to the south (CLIP), an oceanic plateau outcropping in the Southern Peninsula, and terranes of island arc crust to the north, a rare case of ongoing obduction in a transform context. This setting, consistent with the source mechanisms of the Mw7.0 January 2010 and Mw7.2 August 20121 earthquakes in southern Haiti, has significant implications in terms of regional seismic hazard.
Runoff modeling in the High-Mountain River Basin: A Case Study of the Terek River (Caucasus, Russia)
Authors: Kornilova Ekaterina , Krylenko Inna , Rets Ekaterina , Motovilov Yuri
Published: March 2022

Climate change and deglaciation in the 20th and 21st centuries cause runoff changes of a high-mountain regions. Modeling allows to predict runoff changes and possible extreme events in the future. In this research, we performed hydrometeorological data analysis, model calibration and validation in the key parts of the Terek River basin and simulated runoff and it’s components for a long-term historical period.

The Terek River flows from the highlands of the Central Caucasus and streams in an easterly direction, flowing into the Caspian Sea. Runoff modeling of the Terek River was carried out to the Mozdok outlet. The average height of the river basin is 1700 m, the basin area is 20600 km2, of which 34% is the high-altitude part of the basin (>2000 m). A rise in both amount of water availability and potential natural hazard is characteristic of the North Caucasus that is considered to be caused by recent climate change. Mean annual runoff during 1978-2010 increased compared to 1945-1977 by 5-30 % in the foothills and by 30-70% in the plain area.

The ECOMAG runoff formation model (author Y. Motovilov) was adopted for the high-mountain part of the Terek River basin. The input data for the model are meteorological data (temperature, precipitation, air humidity deficit), soil and landscape information, and a digital elevation model, output modeling results – water discharges in a river network. In addition, the runoff formation model allows to analyze all components of water balance in different parts of a river basin and to divide the hydrographs by types of nutrition.

As a result, a long-term historical period from 1977 to 2018 was modeled. Due to the regional features of the river basin, an additional block of the model was included to account the glaciation. In addition to the daily runoff data, the separation of the flow into components in a key part of the river basin (the Baksan River) was used to validate the model. Based on the results of the calibration and verification of the model, a good agreement was obtained between the model and actual discharges for hydrological stations in the mountainous part of the basin. The NSE criterion for the 2009-2018 verification period was 0.75, the simulated and actual volumes of runoff differ by less than 10%.

The Terek River runoff formation model was developed under the financial support of RFBR 21-55-10003. Validation of the model based on the separation of the flow into components were designed within the framework of the Governmental Order to Water Problems Institute, Russian Academy of Sciences, subject no FMWZ-2022-0001.
The paleoenvironmental history of the wetland Gelba in the Gamo Highlands of Ethiopia: a Holocene vegetation reconstruction with sedimentary ancient DNA
Authors: Augustijns Femke , Giguet-Covex Charline , Tilahun Alemayehu Kasaye , Broothaerts Nils , Verstraeten Gert
Published: March 2022

Multiproxy paleoenvironmental research in Ethiopia is limited to a handful of studies, mostly situated in central and northern Ethiopia. This results in lasting uncertainties about the nature and timing of the vegetation response to climatic changes such as the African Humid Period and the Holocene aridification, and the imprint of human activities on the vegetation.

Here we present the sedimentary ancient DNA (sedaDNA) and XRF results as part of a multiproxy study in the Gamo Highlands in the southern Ethiopian rift valley. A six meter long sediment core spanning the last 18 thousand years was retrieved from a wetland at Gelba at 2300 m asl in the Gamo Highlands. Previous pollen and charcoal analyses on the core showed a past vegetation dominated by Afromontane forest taxa over the entire record. A first shift in the pollen-based reconstructed vegetation was a decrease of afroalpine vegetation around 13 cal. ka BP, with a relative increase of Afromontane forest taxa. Around 7 cal. ka BP wooded grassland taxa increased. At ca. 2.5 cal. ka BP a sudden change in the vegetation was detected, with increased disturbance indicators and charcoal particles.

Samples spanning the entire core we analyzed for their plant DNA content targeting the extracellular DNA. For the last 2.5 cal. ka BP, both extracellular and total DNA extraction was applied to the investigated samples. The results showed similar results for both approaches, whilst them also being complimentary by each detecting additional taxa. The majority of DNA sequences was derived from herbs and wetland plants, indicating a relatively local vegetation signal. A first observable change in the DNA record occurs at 7 cal. ka BP (with e.g. decreasing Convolvulaceae), but the strongest shift is observed in the period 2.5-2 cal. ka BP, with in particular an increase of Lythraceae and Polygonoideae. The DNA analysis has some taxa in common with the pollen analysis, but both proxies complement each other strongly due to the dominant local versus regional signal they provide. Despite the difference in detected plant taxa, the timing of vegetation transitions matches well between both records.

The XRF results show a highly minerogenic sediment input in the late glacial period. From ca. 13 cal. ka BP, a strong decrease in minerogenic input is observed and the sediment becomes more organic. At ca. 7.5 cal. ka BP, the minerogenic input increases again until 3 cal. ka BP, followed by fluctuating levels of minerogenic elements and increasing phosphorus levels in the last 2000 years.
Innovative calibration strategies for quality assurance and quality control of reactive trace gas analyzers
Authors: Hofmann Magdalena E. G. , Bent Jonathan , van Zwieten Ruthger
Published: March 2022

Reliable sub-ppb monitoring of reactive trace gas concentrations is essential for industrial and air quality monitoring purposes. Calibrating reactive trace gas analyzers is challenging because of the lack of certified primary standards.

Here we present a three-fold approach for calibration (validation) of Picarro’s Cavity Ring-Down analyzers (CRDS) for reactive trace gas monitoring: (i) calibration of a golden analyzer, (ii) validation of linearity using a surrogate gas approach, and (iii) accurate determination of the zero value. We use formaldehyde (H2CO) to highlight best practices for QA/QC of reactive trace gas measurements and we demonstrate that this strategy can be applied to other reactive trace gases, such as NH3, HCl, H2O2, and HF.

The golden analyzer approach is based on a carefully calibrated inhouse reference instrument that is used as a transfer standard to cross-calibrate production units. After initial scaling based on the spectroscopy of Saha et al. [1], we present new data of primary formaldehyde standards (Apel-Riemer) that are used to adjust the scale of the golden formaldehyde analyzer.

The surrogate gas validation approach is based on the principle that the accurarcy and linearity of the analyzer can be validated using a surrogate gas standard that is non-reactive, commercially available, and has a spectral adsorption line adjacent to the primary gas. In the case of formaldehyde, methane (CH4) meets these criteria, and using methane standards therefore remove the need for regularly measuring formaldehyde standards.

Accurate and regular determination of the zero value of a trace gas analyzer is key to achieve the highest data quality. We discuss the use of different scrubbing agents (DrieRite, 4,2-DNPH cartridges, activated charcoal) in combination with an automated valve switching procedure to track the zero drift of the G2307 formaldehyde analyzer (typically <0.33ppb in 72hrs).

Reference

[1] Saha et al., Molecular Physics, 2007

 
Analysis of the influence of land use on the runout area of shallow landslides
Authors: Giarola Alessia , Bordoni Massimiliano , Tarolli Paolo , Zucca Francesco , Galve Jorge Pedro , Meisina Claudia
Published: March 2022

According to the Centre for Research on Epidemiology of Disasters, every year landslides are to be blamed worldwide for at least 17% of all fatalities from natural disasters. Rainfall-induced shallow landslides are responsible for a significant number of those: they mobilize the first few meters (usually <2m) of soil, have high velocities and occur after abundant and prolonged rainfall events.

The runout of a landslide, defined as the difference between the total area of a landslide and its source area, from which the sediment is first mobilized, is what determines how far a landslide travels and how big the affected area is, and yet the runout is often neglected when it comes to analysing the overall hazard caused by potential landslides.

The land use practices have been proven as one of the factors which impact the susceptibility of an area to the formation of shallow landslides, it is however less clear if the land use also plays a role in influencing the size of the area of runout.

The aim of the present work is to investigate the correlation between the runout area and the land use in which the shallow landslide develops.

To do so, two inventories of landslides, which occurred in neighbouring regions in Northern Italy (Lombardy and Piedmont), comparable for lithology, land use, geomorphology and climate, were analysed.

The result of the analysis was that there were statistical differences in the distribution of the runout among different land use classes, meaning that an influence of the land use on the runout was highly probable. Such results could improve the comprehension on shallow landslides mobility and runout and could lead to the development of possible models of assessment of the runout at different scales.
Sub-surface fault slip dynamics during the 2021 Reykjanes unrest (Iceland)
Authors: Bufféral Simon , Panza Elisabetta , Mannini Stefano , Ruch Joël
Published: March 2022

The dynamics of fault slip in the upper hundreds of meters of Earth’s crust has long been an open question, as their behavior differs from classical elastic dislocation models and their observation still raises challenges. Here, we analyze centimeter-scale ground resolution aerial optical images of the surface ruptures associated with the 8 Mw ≥ 5.0 sub-surface earthquakes that stroke during the Reykjanes seismo-tectonic unrest, starting on February 24, 2021, and ending with the start of an eruption at Fagradasfjall on March 19, 2021. For four major earthquakes, we apply a sub-pixel correlation technique of pre-, syn- and post-crisis aerial and drone orthomosaics to describe the displacement field on surface blocks. We find that surface offsets reached up to 50 cm, with almost pure dextral strike-slip in a NS direction. These orientations contrast with the overall NE-SW-oriented extensional structures originating from magmatic intrusions and appear as a bookshelf faulting system conjugated to the left-lateral strike-slip plate boundary, oriented ~N070.

On hard grounds (e.g.: lava flows), shallow ruptures reached the surface, reactivating pre-existing structures and displaying an en-échelon succession of hectometric-sized fractures. We believe these ruptures are representative of medium-sized faults behavior in the last few hundred meters of the crust. On soft grounds, however, the rupture was only betrayed by meter-sized en-échelon systems, evidenced by thousands of discrete sub-metric surface fractures we were able to observe in the field and map from the orthomosaics. The sharp deformation gradient we imaged indicates that the dislocation drastically decreased above ten to a few tens of meters below the surface. In this layer, diffuse deformation takes on most of the slip deficit, mainly through inelastic processes. As a result, evidence of the February 2021 earthquake did not endure erosion for more than a few months. Except for an isolated sinkhole which allowed us to assume that one fault pre-existed, there were no markers of its presence before the earthquake. We emphasize that this issue must frequently lead to an underestimation of the seismic hazard when performed from surface traces.
Role of climatic oscillations in causing spatially and temporally compound droughts and heatwaves
Authors: ulhassan Waqar , Nayak Munir Ahmad
Published: March 2022

Compound drought and heatwaves (CDHWs) often cause severe ecological and socioeconomic damages; however, these impacts amplify when such temporally compound events occur concurrently in distant regions. Although spatially concurrent univariate extremes (e.g., droughts) have been explored globally and usually linked to large-scale climatic oscillations, such as El-Niño Southern Oscillation (ENSO) and global warming, spatial co-occurrence of CDHWs remains understudied. Here, we present a novel methodology to identify regions that have higher-than-expected chances of experiencing CDHWs concurrently. Using daily precipitation and temperature data from Climate Prediction Centre (CPC) and ERA5, we find robust spatially concurrent CDHWs in multiple regions that are thousands of kilometres apart, revealing teleconnections in CDHWs. Composite anomalies of geopotential heights and sea surface temperatures reveal El-Niño as the major cause of teleconnections in CDHWs in tropical and sub-tropical regions. Height anomalies during extra-tropical teleconnections reveal quasi-stationary Rossby waves that often produce persistent atmospheric blockings over climacteric locations in vicinity of compound regions. The insights gained here offer new avenues in studying spatially and temporally concurrent hydrologic extremes.
A seasonally ice-free Arctic Ocean during the Last Interglacial
Authors: Vermassen Flor , O'Regan Matt , de Boer Agatha , West Gabriel , Coxall Helen K.
Published: March 2022

The extent of Arctic sea-ice during the Last Interglacial is poorly known. Climate models and sediment-based reconstructions generally suggest a relatively extensive ice cover, comparable to the modern day. Here, we show that Arctic sea-ice was much more reduced than previously assumed, with summers being ice-free. Our new evidence stems from a series of central Arctic Ocean sediment cores, including sites that underlie the thickest parts of the modern Arctic ice pack. Microfossil analysis reveals that the Arctic Ocean was invaded by Turborotalita quinqueloba, a typically subpolar planktonic foraminifer that is strongly associated with chilled Atlantic waters in the modern North Atlantic Ocean, and which is absent in modern sediments in the central Arctic Ocean. Given that the modern Arctic Ocean is characterised by a pronounced halocline with Atlantic waters subducting beneath a fresh and cool upper water mass, our findings suggest a shallowing of those Atlantic waters in the Arctic Ocean during the Last Interglacial. This process, dubbed ‘atlantification’, would be associated with retreating sea-ice, allowing T. quinqueloba to invade. Since the onset of the atlantification of the Arctic Ocean in response to climate change is increasingly being reported, we suggest that the Last Interglacial may serve as an important analogue for studying a fully-atlantified, seasonally ice-free Arctic Ocean.

 
Developing a soil moisture Decision Support Tool to quantify the occurrence of flash droughts and saturated soil conditions for pasture grasses in the southeast of the United States
Authors: Maktabi Sara , Gallios Ioannis , Knox Pam , Kukal Sunaab , Vellidis George
Published: March 2022

Extended droughts are known to cause severe damage to crops. Short-term droughts of two to three weeks that occur in areas with high evapotranspiration demands and soils with low water-holding capacity can also significantly affect crop yields although their impact has not been well quantified. These short-term droughts are sometimes referred to as flash droughts. The timing of flash droughts likely has a major impact on whether or not they result in significant yield losses. An ongoing project funded by the U.S. National Oceanic and Atmospheric Administration (NOAA) is quantifying the effect of flash drought on rainfed agronomic crops and pasture grasses in the southeastern U.S. The project is also developing tools to forecast when flash drought periods result in significant yield losses. This paper reports on the development of a tool for estimating daily crop water use and soil water content for three commonly used pasture grasses of the southeastern U.S. – Bermudagrasses (Cynodon dactylon and C. dactylon´ C. nlemfuensis), Bahiagrass (Paspalum notatum), and Tall Fescue (Lolium arundinaceum). Five rainfed farmer-managed fields in which these grasses are grown for hay were instrumented with capacitance-type soil moisture sensors to continuously measure volumetric water content in 12 cm increments to a depth of 60 cm. These data are used to estimate daily crop water use / daily crop evapotranspiration (ETc) which in turn is used to estimate daily crop coefficient (Kc) values using Penman-Montieth evapotranspiration (ETo). ETo is calculated from the University of Georgia Weather Station Network weather stations located near the fields. The final product is a decision support tool that helps farmers quantify the duration of periods of low soil moisture content. The effect on the yield of these flash droughts is quantified by using the DSSAT CSM-CROPGRO-Perennial-Forage crop simulation model.

Keywords: remote sensing, evapotranspiration, crop coefficient, smart irrigation.
Bathymetry inversion with optimal Sentinel-2 imagery using random forest modeling
Authors: Mudiyanselage Sanduni , Abd-Elrahman Amr , Wilkinson Benjamin
Published: March 2022

Bathymetry inversion using remote sensing techniques is a topic of increasing interest in coastal management and monitoring. Freely accessible Sentinel-2 imagery offers high-resolution multispectral data that enables bathymetry inversion in optically shallow waters. This study presents a framework leading to a generalized Satellite-Derived Bathymetry (SDB) model applicable to vast and diversified coastal regions utilizing multi-date images. A multivariate regression random forest model was used to derive bathymetry from optimal Sentinel-2 images over an extensive 210 km coastal stretch along southwestern Florida (United States). Model calibration and validation were done using airborne lidar bathymetry (ALB) data. As ALB surveys are costly, the proposed model was trained with a limited and practically feasible ALB data sample to expand the model’s practicality. Using multi-image bands as individual features in the random forest model yielded high accuracy with root-mean-square error values of 0.42 m and lower for depths up to 13 m.
Natural radioactivity and rock-water interactions in the springs of Sopron Mountains (Hungary)
Authors: Molnár Bence , Baják Petra , Csondor Katalin , Jobbágy Viktor , Izsák Bálint , Vargha Márta , Pándics Tamás , Horváth Ákos , Erőss Anita
Published: March 2022

As groundwater is an important source of drinking water, its quality is of great importance. In recent years, following the EU regulations, radioactivity parameters are also included among the quality measures. 

In the area of the city Sopron (Hungary), groundwater resources are used for drinking water supply. The area had been actively researched for fissile materials, and previous studies measured high radon activity for example in the geophysical observatory (500–1000 kBq m–3)  and in natural springs (up to 220 Bq L–1).

Natural springs bear important information about their parent flow systems, about the transit time and the rock-water interactions along the flow paths. The aim of the study was to investigate the natural springs of the Sopron Mountains and to measure not only the physico-chemical properties (discharge rate, pH, electrical conductivity, temperature, dissolved oxygen content, redox potential, major ion content), but also to determine the uranium, radium and radon activity concentration of the springwaters. 

The measurements revealed low discharge rate (< 5 L min–1), low dissolved solid content (< 450 mg L–1 TDS) and temperature (10–12°C) for the majority of the springs, which indicate that the waters travel in the subsurface along local flow systems. Two springs, which are situated in the foothills, i.e. at lower elevation, show higher dissolved solid content (1115 mg L–1, 481 mg L–1) and higher temperature (15.6°C, 16°C). Their uranium content was also higher, 86–93 mBq L–1. In the case of these springs, the physico-chemical parameters suggest longer travel time, i.e. more time for rock-water interactions which is reflected in their higher dissolved solid and uranium content.

Radon exceeding the 100 Bq L–1 activity concentration was measured in two springs. For the other springs, the radon concentrations were 2-79 Bq L-1.

As all the springs are situated in the regional recharge area of groundwater resources of the area, the study delivered important information regarding the rock-water interactions and the improvement of groundwater quality during subsurface reactions.

 
Antarctic marginal ice zone in the CMEMS GREP ensemble reanalysis product 
Authors: Iovino Doroteaciro , Selivanova Julia , Masina Simona , Cipollone Andra
Published: March 2022

The variability of ice-covered area in the Southern Ocean plays a crucial role in the modulating the exchange of heat, mass and momentum between ocean and atmosphere. Knowledge of ice properties and their variability is necessary for an adequate simulation of those fluxes. Global ocean reanalyses provide consistent and comprehensive records of ocean and sea ice variables and are therefore of pivotal significance for climate studies, particularly in data-sparse regions such as Antarctica.

We present the temporal and spatial variability of Antarctic sea ice area in the CMEMS ensemble of global ocean reanalyses (GREP), over the 1993-2019 period. We assess the accuracy of GREP in reproducing the evolution in time and space of Antarctic total sea ice and discriminating between sea ice classes, the marginal ice zone (MIZ) from consolidated pack ice. GREP provides consistent estimates of recent changes in the Antarctic sea ice area and propery reproduces observed interannual and seasonal variability, linear trend, as well as record highs and lows. For sea ice classes, the ensemble spread is comparable to the spread among observational estimates. GREP is shown to properly represent the variability of pack and MIZ areas during the growing and melting seasons, as well as their minima and maxima. More evident discrepancies between GREP and satellite products occur during summer, when the spread among individual ORA increases. Nonetheless, due to minimization of the single errors, the ensemble mean provides the most consistent and reliable estimates. 

Our analysis suggests that GREP can be used to get a robust estimate of current Antarctic sea ice state and recent trends in sea ice area and extent.
Early Cambrian renewal of the geodynamo and the origin of inner core structure
Authors: Zhou Tinghong , Tarduno John , Cottrell Rory , Nimmo Francis
Published: March 2022

Seismic anisotropy observations indicate the presence of an innermost and outermost inner core, but the origin of this structure is unknown. Records of the past geomagnetic field provide a means to probe inner core evolution by establishing when growth started. The Ediacaran (~565 million-year-old) geodynamo was near collapse, with a strength 10 times weaker than that of the present-day consistent with model predictions for the field before the onset of inner core nucleation. But the timing of the key transition to stronger intensities typical of the Phanerozoic Eon, needed for establishing an exact onset age, has been unclear. We present single crystal paleointensity results from anorthosites of the early Cambrian (~532 million-year-old) Glen Mountains Layered Mafic Complex (Oklahoma). Data from single plagioclase crystals bearing single domain magnetite and titanomagnetite inclusions yield a time-averaged dipole moment of 3.5 +/- 0.9 x 1022 A m2, 5 times greater than that recorded in the Ediacaran Period. This rapid field recovery is the expectation at the start of inner core growth, as new thermal and compositional sources of buoyancy to power the geodynamo become available. We will discuss thermal models, which together with our new paleointensity results, allow us to constrain growth of the inner core and when its structure may have changed.
Saltwater intrusion modelling for the safeguard of crop production in the Mediterranean 
Authors: Botto Anna , Camporese Matteo , Salandin Paolo
Published: March 2022

In coastal aquifers seawater intrusion is a worldwide problem caused by natural processes but significantly worsened by aquifer overexploitation for irrigation and drinking water supply, land subsidence, sea level rise and climate changes, which contribute to the reduction of groundwater natural recharge.

Seawater intrusion represents a relevant environmental issue along the coastal aquifers of the Mediterranean Sea, including the coast south of the Venice Lagoon, a peculiar ecosystem characterized by a fragile equilibrium between reclamation and irrigation activities, whereby salinization is significantly reducing the annual local crop production of about the 25% on average.

Here, we present the test case of Ca’ Bianca, located near the city of Chioggia - Italy. A numerical flow and transport model has been set up with SEAWAT, aimed at reproducing the complex saltwater intrusion dynamics in the area. To pursue this goal, real field water table and concentration measurements are combined to aid in the calibration and validation of the model. Particular attention is devoted to the evaluation of the dynamics and uncertainty associated with seawater levels, an essential forcing of the model. Then, mitigation strategies, such as drains supplying freshwater in the first layer of soil, are simulated to test their effectiveness against the saltwater intrusion in a way that their application can be reproduced also in other sites affected by the same phenomenon.

Results show a good match between the simulations and the data, with errors of about 10 cm for the water table, which is acceptable if we consider the scale of the project and its topographical and stratigraphical uncertainties. Even though matching observed concentrations proved to be more difficult, the model realistically reproduces the saltwater spatio-temporal behaviour. The comparison between the scenarios with and without mitigation strategies shows that, in the latter case, significant enhancement in crop production can be achieved.

As a future development, climate change effects on the sea levels will be considered and predictive scenarios will be developed and quantitatively analysed.