bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical Resistivity Tomography (ERT) Applied to the assessment of Karst Carbonate Aquifers structure: Case Study from Zaghouan-Bent Saidan (NE Tunisia)
Authors: Mhimdi Amal , Gabtni Hakim , Ezzine Ines , Hamzaoui Fadoua , Ghanmi Mohamed , Bouhlila Rachida
Published: March 2022

Abstract:

Karst aquifers belong to the fractured aquifer family. The Zaghouan region located in NE of Tunisia (North Africa) is characterized by a high degree of karstification due to the climate impact and the development of fracture network. Survey using electrical resistivity tomography (ERT) is deployed to provide a cost-effective characterization of the subsurface karst environments. A total of three ERT profiles with a length of 300 meters were evaluated in Zaghouan region.

The area represents an anticline of Jurassic limestone rocks, which is overlain by a thin clay layer. In this study, an ERT survey was conducted to examine the spatial distribution and shape of underground cavities in the karst area of Jebel Bent Saidan. In this study, geological, hydrogeological and electrical resistivity tomography (ERT) methods were applied to determine the geometry of the karst aquifer in the Zaghouan area (NE Tunisia). The area is characterized by fractured and karstic limestone aquifer of Jurassic. Three resistivity profiles were carried out along the study area (Jebel Bent Saidan). The correct resistivity data was interpreted using ZONDRes 2D software.  The results of the interpreted geo-electrical sections showed that the resistivity of the carbonate aquifer ranges from 350 to over 4000 Ωm. The thickness of the aquifer varies between 15 and 30 meters, while its depth from the surface is between 10 and 40 meters. The ERT not only provided accurate near-surface information, but was also very useful in establishing the geometry of the aquifer. It was also very useful in establishing the 3D geometry and position of several potential karst cavities and conduits. The results show the presence of two large isolated cavities at different depths. The low resistivity of karst cavities in the Jurassic carbonate of Jebel Bent Saidane was explained by the saturation of groundwater. The ERT imaging technique using to identify and characterize the discontinuities, faults and water investigation of the fractured and karstified limestone aquifers in the Bent Saidan Mounts. The conducted research demonstrated that the ERT method was an effective tool for imaging the subsurface in the karst terrain.

Keywords: Bent Saidan (NE Tunisia), karst aquifers, electrical resistivity tomography (ERT), cavities.

 
A New Toolset for Multiscale Seabed Characterization
Authors: Ilich Alexander , Misiuk Benjamin , Lecours Vincent , Murawski Steven
Published: March 2022

Terrain attributes are increasingly used in seabed mapping to describe the shape of the seabed. In recent years, many calls have been made to move seabed mapping practices towards multiscale characterization to better capture the natural geomorphic patterns found at different spatial scales. However, the community of practice lacks computationally efficient, user-friendly, and open-source tools to implement multiscale analyses, preventing multiscale analyses from gaining traction for seabed mapping and characterization. Here we present a new R package that enables the calculation of multiple terrain attributes like slope, curvature, and rugosity from bathymetric data. The user-friendly package allows for a repeatable and well-documented workflow that can be run using open-source tools. We also introduce a new measure of rugosity that ensures decoupling from slope. Examples of the performance of the package, including the new rugosity metric, will be presented using bathymetric datasets presenting different characteristics.
Investigating the origin of Mg-spinel exposures on Mons Hansteen Alpha, an evolved silicic volcanic structure on the Moon
Authors: Moitra Himela , Gupta Saibal
Published: March 2022

Mons Hansteen Alpha is a lunar ‘red spot’ that is now considered to be of non-mare volcanic origin. In addition to being characterized by an evolved silicic composition, Mons Hansteen Alpha is also of interest because of the presence of Mg-spinel exposures in association with the siliceous lithology, as detected by the Moon Mineralogy Mapper on board the Chandrayaan-1 mission. The Compton-Belkovich volcanic complex on the Moon is the only other established example of this kind. The origin of Mg-spinel exposures on the lunar surface is considered to be either impact related or endogenic. Models have been proposed in earlier studies to explain the spinel exposures on anorthosites, and spinel in association with other mafic minerals such as olivine and orthopyroxene. However, the origin of Mg-spinel exposures within an evolved siliceous body that has very limited associated mafic minerals is yet to be fully explored. In this study, the Mg-spinel exposures on Mons Hansteen Alpha were analyzed using high resolution LROC NAC images and correlated with topographic information from the SLDEM data. These investigations suggest that in most cases, the spinel exposures on Mons Hansteen are not related to any impact related structures. The exposures are often found on elevated features such as ridges, or around irregular-shaped pits. The distribution of the exposures is mostly limited to the Pitted unit, the youngest unit in the volcanic structure; this favours an endogenic origin instead of one related to impact as otherwise, the exposures would also have been distributed in the other units. On the bases of these observations, it is suggested that the Mg-spinel exposures on Mons Hansteen Alpha are endogenic in nature. A model is proposed for the origin of endogenic Mg-spinel exposures on silicic volcanic structures. For this, model reactions were considered between a lunar picritic basaltic magma and two types of crustal protoliths- (i) a mixture of silica and anorthosite and (ii) a lunar monzogabbro. The modelling has been done using the alphaMELTS 2 software. The proposed model combines the crustal melting model for the genesis of silicic volcanic structures with a genetic model for the Mg-spinel exposures. The mixture of silica and anorthosite has been considered as a possible crustal protolith consistent with recent experimental lunar magma ocean (LMO) crystallization models that crystallized silica as one of the end stage products. On the other hand, earlier studies have proposed monzogabbro as a possible protolith composition for lunar silicic lithology. The models demonstrate the possible pathways of forming silicic compositions similar to the lunar granite samples collected during the Apollo missions, with simultaneous crystallization of Mg-spinel.
Mars Atmosphere Simulations With ROCKE-3D: Nonlinear Dust Cycle Behavior Linked to Dust Radiative Effect
Authors: Perlwitz Jan P , Tsigaridis Kostas , Aleinov Igor , Guzewich Scott D , Way Michael J , Wolf Eric T
Published: March 2022

We present simulation results of the dust cycle on Mars using the NASA Goddard Institute for Space Studies (GISS) ROCKE-3D [1] general circulation model with radiatively active dust aerosol tracers. Dust aerosols are represented by a sectional scheme that partitions the simulated dust mass into eight size classes, covering a total size range from 0.1 to 32 μm particle diameter. The model simulates emission from sources, advection, and turbulent, gravitational, and wet deposition of dust. The strength of the dust cycle can be calibrated with a global factor for the dust emission. ROCKE-3D is coupled to the Suite of Community Radiative Transfer codes based on Edwards and Slingo (SOCRATES) [2,3], which applies Mie theory to calculate scattering and absorption of radiation by aerosols. We carried out a series of experiments over 11 Mars years, for which we varied the strength of the dust cycle, and for radiatively active and inactive dust. The simulated dust aerosol optical depths were compared to gridded retrievals of the dust AOD from measurements over 11 years [4, 5]. We find that the dust cycle displays nonlinear behavior with the strength of emission, when the dust is radiatively active, which is absent for radiatively inactive dust. When the dust cycle strength exceeds a certain threshold the simulated mean annual cycle of dust starts to exhibit features that are similar to the observed mean annual cycle. We hypothesize that feedbacks involving the dust radiative effect introduce important non-linearities, which are essential for reproducing and understanding the observed dust cycle on Mars.

References: [1] Way, M. J. et al. (2017) ApJS, 231, 12.
[2] Edwards, J. M. (1996), JAtS, 53, 1921.
[3] Edwards, J. M., & Slingo, A. (1996), QJRMS, 122, 689.
[4] Montabone, L. et al. (2015) Icarus, 251, 65.
[5] Montabone, L. et al. (2020) JGR Planets, 2019JE006111.

 
An Ensemble Kalman Filter for Estimating Future Slow Slip Events and Earthquakes on 1D, 2D and 3D Synthetic Experiments 
Authors: Diab Montero Hamed Ali , Li Meng , van Dinther Ylona , Vossepoel Femke C
Published: March 2022

Our ability to forecast future earthquakes is hampered by the very limited information on the fault slip that produce them. In particular the current state of stress, strength, and parameters governing the slip of the faults are highly uncertain. Ensemble data-assimilation methods provide a means to estimate these variables by combining physics-based models and observations while considering their uncertainties. Perfect model experiments with an Ensemble Kalman Filter (EnKF), connected with one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) earthquake cycle models, demonstrate the ability to estimate the state variables of shear stress, slip velocity, and state (θ) of a straight fault governed by rate-and-state friction surrounded by a homogeneous elastic medium. The models represent a direct-shear laboratory setup in one, two and three dimensions, with an array of shear-strain gauges and piezoelectric transducers located at a small distance to the fault. In this research, we compare the recurrence interval and earthquake occurrence of the EnKF across the different models to better understand the challenges associated with a space-time systems with increasing dimensions and increasingly complex earthquake sequences. The assimilation of synthetic shear-stress and slip-rate observations improves in particular the estimates of shear stress and slip rate on the fault, despite the very low accuracy of the observations. We get reasonable estimates when modelling long-duration earthquakes or slow slip events . Interestingly, we also obtain very good estimates when simulating earthquakes with fast slip rates (up to m/s). The large, nonlinear, changes in stress and velocitiy  during the fast transition from the interseismic to the coseismic phase cause the distributions of the state variables to become bi-modal. The EnKF still provides a reasonable estimate of the time of occurrence of the earthquakes in the synthetic experiments, despite the inherent assumption on the Gaussianity of these distributions.
Microscopic and microanalytical investigation of concrete for road pavement slabs and highway pylons
Authors: Marrocchino Elena , Paletta Roberta , Vaccaro Carmela
Published: March 2022

Cement has good compressive properties but poor tensile strength, which is critical of its composites. To solve this challenge, in the last decades, different types of reinforcing fibers, such as glass, carbon, polyvinyl alcohol, steel, asbestos, aramid, or cellulosic fibers have been used. The main benefits of adding reinforcing fibers in cement are the improvement of tensile strength, flexural strength and toughness, due to this, in the late 1960s in some European motorways, have been used concretes for road pavement slabs and for pylon with asbestos and fibrous minerals in the mixture. Anyway, the cumulative traffic loading and the exposure to weathering, especially the impact of chloride diffusion for use of de-icing salt, can induce severe degradation phenomena affecting both the concrete and the asbestos mineral fibers. Highway and street pavements are massive civil infrastructures. Highway and street pavements are massive civil infrastructures and in Italy, in the last decade, the structural suitability of hundreds of thousands of kilometers of motorways is under verification due to degradation phenomena.

A combination of different analytical methods was used to characterize concrete samples affected by self-passivating due to calcite fouling and biofilm, presumably mainly caused by transporting water rich in salts. Samples have been studied by optical microscopic observation and by Scanning Electron Microscopy-Energy Dispersive (SEM-EDS) analysis. It has been hypothesized that seasonal variations of water temperature and high chemical interaction water-concrete should be responsible for the hydrolysis and Ca leaching that cause the degradation of the cement paste and the exposure of asbestos mineral fibers to weathering.

Potential risks during maintenance interventions should be taken into consideration, in this light, mineralogical and petrographic characterization of concrete for road pavement slabs and for pylon is a useful tool for investigating the presence of potentially dangerous minerals that required caution during degradation product removal with methodologies that pulverize the samples. To prevent effective post-degradation transformation into elements harmful to health and the environment, careful monitoring is recommended.
Monitoring of an aquifer thermal storage system in the field scale using crosshole ERT
Authors: Birnstengel Susann , Günther Thomas , Pohle Marco , Hornbruch Götz , Nordbeck Johannes , Ködel Uta , Werban Ulrike , Dietrich Peter
Published: March 2022

Heat storage in aquifer structures takes on greater significance and is therefore an important subject for risk assessment and impact analysis on groundwater resources. Geophysical methods contribute substantially to the observation of hydrogeological processes by providing information
about physical subsurface properties. In order to allow for correct process interpretation, it is essential to find and evaluate their relationship
to the corresponding rock-physical parameters. Therefore a heat injection experiment and a corresponding monitoring system have been developed
and established in a shallow aquifer environment characterized by quaternary glaciofluvial sediments. The focus is on the investigation of coherence between geophysical proxies and the temperature distribution in the near-surface. A geological subsurface model derived from geophysical and hydrological pre-investigations has been used to simulate heat distribution and resulting electrical conductivity variations in the affected area.
Tests for thermal energy storage and extraction have been conducted via Aquifer thermal energy storage (ATES) system. With time-lapse inversion
we want to detect the direct impact of changing temperature distribution in the subsurface on the related electrical resistivity when heating the
aquifer up to 80 °C. Rein et al. (2004) state that electrical conductivity of the subsurface depends to a great extent on water saturation. Heating
up the governed pore water by 1 °C results in a linear relative electrical conductivity increase of 2.5% (Dachnov, 1962). Different inhole and cross-
hole arrays at the test site assure good coverage of the heated area and pass through the monitoring routine once a day. The ongoing injection
cycles consist of a heating period of 2 weeks, a down time of 3 weeks, an extraction period of 2 weeks and another down-time of 1 week followed by
the next cycle. We prove the applicability of heat injection and extraction monitoring by combined crosshole ERT (and seismic) and correlated
the resistivity with the directly measured temperature data of the temperature sensors additionally installed in the boreholes. At the highest
observed temperature level of 75 °C the electrical conductivity increases by a factor of three. 3D inversion allows for a direct reference to the temperature distribution in the subsurface. This study provides information about the resolution capacity of crosshole ERT for heat storage systems
in shallow aquifers.
These activities have been done within the follow-on TestUM-Aquifer Project - TestUM-II ”Cyclic high temperature - Aquifer thermal energy storage (ATES) experiment” funded by the BMBF (grant 03G0898A/B).
Atmospheric Mercury Depletion Events: Assessment Impact of Meteorological Parameters in the Arctic Winter
Authors: Pankratov Fidel , Mahura Alexander , Masloboev Vladimir , Popov Valentin
Published: March 2022

In 2001, the mercury analyzer was installed at Amderma (69.450 N, 61.390 E, 49 m above sea level; Yugor Peninsula) in the Nenets Autonomous Okrug (Russia) to carry out continuous measurements of gaseous elemental mercury vapor concentration in the atmospheric surface layer. The data analysis demonstrated that the atmospheric mercury depletion evens (AMDEs, concentration < 1 ng m-3) are observed on a rather limited territory, i.e. along the coast of the Arctic seas. During observational period (2001-2015), the analyzer was placed at three locations at different distances (8.9 km – 2001-2004, 2.5 km – 2005-2010, and 200 m - 2010-2015) from the Kara Sea coast.

For the AMDEs cases, during winters of 2001-2004 the air temperature was in range from -150С to -310С and relative humidity – 68-84%. The dominated atmospheric transport for these cases was mainly observed from the N-N-W direction. The number AMDEs relative to all measurements was about 0.2%. For 2005-2010, the temperature ranged from -10С to -370С and relative humidity – 74-83%. The atmospheric transport – from the E-E-N direction. The number AMDEs relative to all measurements was 2.7%. For 2010-2013, the temperature varied from -220С to -270С and relative humidity – 75-87%. The atmospheric transport – mainly from the S-S-W direction. The number AMDEs relative to all measurements was 26.9%, showing substantial 10-fold increase of AMDEs compared with the previous period. As a result, all cases correspond to range of air temperatures from -10C to -370C and relative humidity of 68-87% for entire monitoring period considered.

For selected considered episode (29-30 Mar 2002), the air temperature varied from -260C to -310C, and when it decreased to the minimum, the effect of mercury depletion was detected with the lowest concentration (0.39 ng m-3). For episode (29 Feb - 1 Mar 2007), the temperature was also decreasing from -160C to -370C, and at reaching the minimum, the mercury concentration was also the lowest (0.12 ng m-3). Moreover, in Dec 2006, for the first time, a significant number of AMDEs cases (23 events) was recorded during the polar night. In Feb 2010 the longer duration (up to 40 hours) AMDEs episodes were observed compared with Jan (up to 15 hours).

Note that all AMDEs are generally observed at lower air temperatures and relative humidity values with respect to the average values.
What is the contribution of stress redistribution in earthquake swarm dynamics?
Authors: Dublanchet Pierre
Published: March 2022

Earthquake swarms are generally interpreted as resulting from the redistribution of stresses within the crust. Swarms develop in response to fluid flow and poro-thermo-elastic stresses in reservoirs, aseismic slip on major faults, or during magmatic events in volcanic areas. However, our ability to quantify stress changes at depth from the observation of earthquake swarms is still very limited.  In his seminal study (Dieterich, 1994) was able to develop a model leading to a quantitative relationship between stress and seismicity rate. This model, based on non-interacting spring-and-slider systems undergoing rate-and-state friction was successful in determining stress conditions from seismicity rate in several active areas involving both tectonic and magmatic processes. This approach nevertheless relies on very strong assumptions, one of them being that no stress redistribution occurs following an earthquake. Stress redistributions are however known to drive earthquake sequences as observed during foreshock aftershock sequences. Ignoring this contribution might lead to wrong estimations of stress conditions at depth from seismicity rate.
In order to evaluate the role of stress redistribution in earthquake swarm dynamics, I present a new physics based earthquake simulator extending Dieterich's model. It consists of a set of planar rate-and-state frictional faults distributed in a 3D homogeneous elastic medium, and loaded by a prescribed stress history. Faults can have any size and orientation. Stress redistributions are thus fully accounted for.
The model is then used to investigate the relationship between seismicity rate and stressing history under different loading conditions (constant tectonic stressing, periodic loading) and fault properties (initial stress, frictional properties, relative distance between faults). In many cases, Dieterich's theory ignoring stress transfers captures many features of the seismicity rate patterns. This is particularly true for periodic loading, which generates frequency dependent seismicity modulation: at low frequency, seismicity rate scales exponentially with the loading stress, while at higher frequencies it tracks the stressing rate. The period separating the two modulation regimes is correctly predicted by Dieterich's theory. Under constant loading, seismicity rate is also constant (as predicted by Dieterich's theory) if the sequences are analysed over long enough time series involving several seismic cycles on each fault. At a shorter time scale however, significant clustering (not predicted by Dieterich's approach) arises, in particular for compact fault distributions enhancing the stress redistributions. 
More generally, the approach presented here allows to define the mechanical conditions leading to a significant contribution of stress transfers in the development of earthquake swarms.
Modelling injection induced seismicity in the Hengill geothermal field
Authors: Rinaldi Antonio Pio , Ritz Vanille , Nandan Shyam , Castilla Raymi , Karvounis Dimitrios , Wiemer Stefan
Published: March 2022

The Hellisheiði Geothermal Field is situated in Southwest Iceland and composes the Southern part of the Hengill Volcanic System. This area is characterized by a complex triple junction between three tectonic features: the Reykanes Peninsula rifting, South Iceland Volcanic Zone and West Volcanic  Zone. Reinjection of spent geothermal fluids is distributed mostly in two areas (Gráuhnúkar and Húsmúli), comprising respectively 6 and 5 active injection wells. The Húsmúli reinjection area, commissioned in September 2011 and has seen significant seismicity associated with drilling and injection operations.
In the framework of the Geothermica project COSEISMIQ (http://www.coseismiq.ethz.ch/en/home/), a dense temporary network was installed to monitor the seismicity in the Hengill region between December 2018 and August 2021. With this enhanced network, novel analysis and relocation techniques, a high resolution relocated catalogue was curated and comprises over 3600 events in the Húsmúli area.
We use numerical models, some purely statistical (ETAS and Seismogenic index) and a hybrid model (TOUGH2-Seed) to reproduce observed seismicity in the Húsmúli reinjection area during the COSEISMIQ project. We employ a pseudo-forecasting approach and compare models performances
and fit to the recorded data.
Modelling study of potential contamination of chemical warfare agents (CWA) from collapsing shipwreck hull in Skagerrak region
Authors: Jakacki Jaromir , Tørnes John Aa , Johnsen Arnt , Muzyka Maciej , Przyborska Anna
Published: March 2022

It is well known, that after World War II, during the Potsdam Conference, the decision was made to demilitarize Germany, resulting in ammunition containing Chemical Warfare Agents (CWA) being dumped into the selected dumpsites area of the Baltic Sea. In some other region, such as Skagerrak, ammunition was loaded on ships that were sunk. Some ships have been damaged in sinking at sea, causing munitions to be scattered on the seabed, while others are still relatively intact (Tørnes et al., 2020).  Some of the bulk ammunition has been observed to be opened by corrosion (Hansen RE, et al. 2019)

A few decades later, scientists wondered what consequences a leak from such dumped munitions could have on the marine ecosystem. Although, more than 70 years have passed since World War II, the impact of a potential leak of the CWA has not been properly assessed yet.

The main goal of this work is to assess pollution from a CWA release from a collapse of the entire shipwreck’s hull in the Skagerrak area. As a main tool High Resolution Dispersion Model (HRDM, Jakacki et al. 2020) has been used for estimating the leakage from the wreck. The horizontal resolution of this model has been increased to about 10 meters for properly holding the release processes and currently, the domain of the model covers an area about 525 km2. In our work we will take into account three chemical agents: sulfur mustard, Clark I and tabun. It is planned to make different scenarios that will represent different hydrodynamic conditions in shipwreck area. The calculations will also include the degradation processes of sulfur mustard and tabun, which are not stable in sea water.

 

Hansen, R. E., Geilhufe, M., Bakken, E. M., Sæbø, T. O., Comparison of synthetic aperture sonar images and optical images of UXOs from the Skagerrak chemical munitions dumpsite. Underwater Acoustics Conference & Exhibition (UACE) 2019 s. 429-436,

Jakacki J., Andrzejewski J., Przyborska A., Muzyka M., Gordon D., Nawala J., Popiel S., Golenko M., Zhurbas V., Paka V., High resolution model for assessment of contamination by chemical warfare agents dumped in the Baltic Sea , Marine Environmental Research, doi: 10.1016/j.marenvres.2020.105079

Tørnes J. Aa., Vik T., Kjellstrøm T.T., Leakage rate of the nerve agent tabun from sea-dumped munition, Marine Environmental Research, doi: 10.1016/j.marenvres.2020.105052

 

 

Calculations were carried out at the Academic Computer Centre in Gdańsk

 
 
Attribution of 2021 Weather Extreme Events in British Columbia
Authors: Malinina Elizaveta , Gillett Nathan , Kirchmeier-Young Megan , Zhang Xuebin , Anslow Faron , Zwiers Francis
Published: March 2022

In British Columbia, and in the Pacific North West America in general, 2021 was a year fraught with extreme weather events. First, in late June 2021 an unprecedented heat wave claimed over 600 lives, followed by in an extreme flood in mid-November that became one of Canada’s one of most expensive natural disasters. In this study, we provide separate attribution of these two events using CMIP6 temperature and precipitation data. For both events, we compare the current climate data with that from prior decades as well as data for the end of the 21st century under the SSP2.45 scenario. By fitting generalised extreme value distributions to all datasets, we were able to quantify the risk ratios as well as provide analysis of the changing frequency of such extreme events with in a warming climate.
Effect of rainfall temperature on the erosion of clayey soils different in clay amount: experiments with a laboratory rainfall simulator
Authors: Shkedi David , Sachs Eyal , Pariente Sarah
Published: March 2022

As previously foreseen, it seems like climate change effects have begun to take their toll on the environment globally, but especially in the Eastern Mediterranean-Middle East (EMME) region where a hot climate already prevails. Some of these effects include higher temperatures during summer season, greater heat stress, longer summers, lower soil moisture, greater water scarcity, more intense rainstorms, longer duration between rainstorms, reduced air quality due to greater pollution and more. Rainfall temperature is also a variable that potentially will be affected by changes in climate regime.

These alterations in climate regime might play an even greater role in soil erosion which has already become a concern on a global scale due to its impairing effects on human activity. Although, soil erosion variables have been studied extensively on various levels, very little has been researched on the effects of rainfall temperature on the soil. A few years ago, comparative research with a laboratory rainfall simulator was conducted on two soils, a clayey soil and loamy soil from Israel, in dry and wet conditions, under different rainfall temperature regimes. The researchers concluded that rainfall temperature has an impressionable effect on runoff and soil erosion that must not be ignored, and which is more pronounced in the clayey soil. Recently, and in accordance with these findings, follow-up research was conducted on two pre-wetted clayey soils, 43% and 64% clay content, respectively. The Terra Rosa soils were chosen from different locations in Israel and are similar to each other in salt concentration, organic matter content and land use (plots between olive trees in an olive grove), yet are different from one another in clay content, and possibly in clay-mineral type as well. The soils were pre-wetted and allowed to drain to field capacity state, and then were exposed to 21 mm/hr rainfall events at 3 different temperatures: 2, 20 and 35 degrees Celsius, respectively. Runoff and soil samples were collected throughout the experiments. Temperature was monitored at water tank, nozzle, soil surface and soil subsurface with thermocouples and a thermal camera. Each experiment was repeated 4 times on 2 different soils with 3 different temperatures, rendering a total of 24 experiments.

In this presentation, I will demonstrate our theory for the potential of rainfall temperature as an important variable on soil erosion and will present our initial findings based on our recent experiments.
Operational water forecast assessment of a spatially distributed process-based snow model; a case study in the East River Watershed, Colorado, USA
Authors: Meyer Joachim , Skiles McKenzie , Kormos Patrick , Hedrick Andrew , Trujillo Ernesto , Havens Scott , Marks Danny
Published: March 2022

Operational water-resource planning faces an increased challenge with a changing seasonal snowpack in mountain watersheds due to global and regional climatological factors. An example region is the Western United States, where there is a demonstrated decline in extent and amount of seasonal snow in mountain ranges such as the Sierra Nevada, California, or the Rocky Mountains, Colorado. Causes for the shift include precipitation phase changes or increased amounts of dust on snow. Like the Colorado Basin River Forecast Center (CBRFC), regional forecasters cannot currently account for these factors when their prediction method relies on an empirical snow model based on historic calibration records. To evaluate the options and supplement the current method of the CBRFC, we run a physical-based snow energy balance model for past water years in a subset region; the East River Watershed, Colorado. The results are compared with in-situ measurements, remote sensing observations, and the predictions by the current model. This assessment is an effort to include the process based model in day-to-day CBRFC operations and to create a foundation to expand to larger domains. This project also bridges the gap between scientific advancements and benefits for society with more accurate water resource forecasting.
 Storm Time Radiation Belt Electron Energization Characteristics Using The WINDMI Model
Authors: Srinivas Pavithra , Spencer Edmund
Published: March 2022

Radiation Belt Storm Probes (RBSP) data show that seed electrons generated by substorm injections appear to play a significant role in amplifying chorus waves in the magnetosphere. The wave-particle interaction then leads to rapid heating and acceleration of the electrons to 10's to 100's of keV energies [1], [2], [3], [4]. These electrons are injected into the outer Van Allen zones [5].

In this work, we use the WINDMI model of the nightside magnetosphere to generate a proxy index that tracks electron energization in the radiation belts during storm time. The electron energy ranges analyzed are 40 KeV to 4.2 MeV.

The WINDMI model has as an output, a region 1 field-aligned current proportional to the westward auroral electrojet. This field-aligned current is integrated to generate a proxy E Index, or Electron Energization Index, incorporating a variable time delay and energy loss rate. The resulting linear differential equation is coupled to the WINDMI model, and we used this to study a set of 8 events.

The E index is compared to RBSP data and GOES data. We initially analyzed a dataset of 27 magnetic storms from the year 2014 to 2017. These events occurred over diverse durations and were of different intensities. The storms were analyzed with respect to the SML index and the AL index.

From the 27 events, eight storms were selected for further analysis. These were were 17-27 March 2015, 21-29 June 2015, 6-9 August 2017, 7-11 May 2016, 23-31 October 2016, 14-21 March 2015, 5-12 October 2015 and 7-12 November 2017. 7-11 May 2016 and 14-21 March 2015 storms were dropped because they showed similar signatures to the other storms presented.

1)Reeves, G. D., et al. ( 2013), Electron acceleration in the heart of the Van Allen Radiation Belts, Science, 341( 6149), 991 994, doi:10.1126/science.1237743.2) Foster, J. C., et al. (2014),

2)Prompt energization of relativistic and highly relativistic electrons during substorm intervals: Van Allen Probes observation, Geophys. Res. Lett., 41, 20 25, doi:10.1002/2013GL058438

3)Baker, D. N., et al. ( 2014a), Gradual diffusion and punctuated phase space density enhancements of highly relativistic electrons: Van Allen Probes observations, Geophys. Res. Lett., 41, 1351 1358, doi:10.1002/2013GL058942

4)Kanekal, S. G., et al. ( 2015), Relativistic electron response to the combined magnetospheric impact of a coronal mass ejection overlapping with a high speed stream: Van Allen Probes observations, J. Geophys. Res. Space Physics, 120, 7629 7641, doi:10.1002/2015JA021395

5)Jaynes, A. N., et al. ( 2015), Source and seed populations for relativistic electrons: Their roles in radiation belt changes, J. Geophys. Res. Space Physics, 120, 7240 7254, doi:10.1002/2015JA021234 .
Multi-site precipitation time series generation using Fourier Transform
Authors: Mehrvand Masoud , Bárdossy András
Published: March 2022

This study introduces hourly precipitation time series generator at multiple stations by using Fourier transform. Proposed method is based on two transformations of observed data. First, transforming from observed data to binary data, using a threshold occurrence frequency. The autocorrelation is calculated for these indicator series. Second, transforming the previous binary correlation to Gaussian correlation and calculating the power spectrum. These two transformations enable the use of Gaussian processes for the simulation of precipitation using phase randomization. The simulated Gaussian series are transformed back to precipitation using the observed marginal distributions. For the use for multiple sites phase differences of observed time series are taken into account. This method is tested for multiple nearby stations in Baden Württemberg state, Germany but it can also be applied for larger scales.
Estimation of maize sowing dates from Sentinel 1&2 data, over South Piedmont
Authors: Rolle Matteo , Zribi Mehrez , Tamea Stefania , Claps Pierluigi
Published: March 2022

Information of crop sowing dates is important to enhance the accuracy of crop models and for the assessments of crop requirements during the growing seasons. The sowing calendars of densely harvested areas are often driven by heterogeneous factors like annual crop rotations, crop switches and the alternation of winter and summer products over the same fields. Remote sensing is widely used for agricultural applications, especially to maximize crop yields through precision farming tools. Indices combining optical and infrared bands are particularly suitable for the crop classification algorithms and the plant health monitoring. Synthetic Aperture Radar (SAR) is often used in agriculture to classify irrigated and rainfed fields, due to its high sensitivity to soil water content. Despite SAR data are also used to identify changes in the ground roughness, this information has been rarely combined with optical data to identify crop sowing dates at the field scale.

In this study, SAR data from Sentinel-1 and NDVI derived from multispectral (MSI) acquisitions of Sentinal-2 have been used to identify the sowing dates of maize over a densely harvested pilot area in South Piedmont (Italy). NDVI data have been used to identify maize fields together with the agricultural geodatabase provided by the Piedmont public authority. The moisture-induced noise of SAR data has been filtered to avoid the impact of precipitation on the radar signal during the bare soil phase. Combining the VH and VV bands acquired by Sentinel-1 it was possible to identify the moment when maize plants break through the soil in each field.

Results show a good alignment with the information of sowing periods acquired from local farmers, also in terms of multiple growing seasons due to the presence of different maize types. The distribution of sowing dates points out that most of the maize is sown during the second half of May, while the other fields are sown even a month later after the harvesting of winter crops. The method proposed in this study may lead to significant applications in the agriculture monitoring, providing useful information for crop-related management policies. The combined use of SAR and NDVI data has the potential to improve the crop models for the benefit of yields and food security.
Assessment of the Recent Tendencies of the Winter Precipitations and the Snow Cover in Bulgaria
Authors: Nikolov Dimitar
Published: March 2022

Snow is an essential meteorological element and also an indicator of the fluctuating climate, resulting from change in the regime of winter precipitation and air temperature. Taking into account the recent tendencies of a warming climate, it is important to quantify these changes and their influence on snow amount and duration, which have significant consequences on several economic and environmental aspects.

Data from 20 stations with altitudes ranging from 50 up to 2925 m a. s. l. for the period 1961-2017 have been used for testing of the following winter characteristics: mean monthly air temperatures, days with snowfalls, days with rains and days with mixed precipitation and the corresponding monthly precipitation amounts. The air temperatures during snowfalls have been also examined. Except for the stations at highest altitudes (above 2000 m) no significant trends in precipitation quantities have been found. Decreasing trends of the days with snowfalls and the opposite for the days with rain and mixed precipitation have been detected. Almost all of stations show also increasing trends of the air temperatures both monthly as well as event based. Most of these trends are significant at 0.05 level. One secondary effect of this temperature rise is the enhancing of the severe wet snow events, which have been considerably intensified recently.

Another 35 stations with long data sets (1930/35 – 2019) have been used to evaluate the following snow characteristics for 3 main climatological reference periods – 1931-60, 1961-90 and 1991-2020: days with snow cover, averaged and maximal snow depth. No significant change for the maxima has been detected but the comparisons of other two variable depict significant differences.

This study has been funded by the National Science Fund in two separated projects under the contract numbers DM14/1 in the program for junior researchers and post-doc and KP-Austria-2 in the bilateral scientific program with Austria.
Interannual variations of CO2 deposit in Martian caps from the HEND/Odyssey data.
Authors: Litvak Maxim , Mitrofanov Igor , Sanin Anton
Published: March 2022

It is known that growing and sublimation of Martian snow caps is seen as seasonal variations of neutron flux above Martian polar regions. The surficial CO2 deposit attenuates (depends how thick the deposit is) the neutron signal originated at deeper subsurface layers enriched with water ice. It makes neutron observations a valuable technique to monitor behavior of seasonal caps and study their evolution within seasonal cycle or search for inter annual variations. The measured counting rate in neutron detectors and its seasonal variations could be interpreted in terms of column depth (g/cm2) and mass (kg) of the seasonal CO2 deposit based on the numerical models of neutron production and scattering in Martian atmosphere and surface (including upper layer of temporal CO2 deposit).
HEND/Odyssey is continuously operating on Mars orbit and mapping Martian neutron albedo since February 2002 covering period of almost 20 years. Up to now it corresponds to about 10 Martian years. The availability of so long-term and continuous data set could be used to search interannual variations of seasonal cycle. 
It was found that observations made during different martian years do not match each other in winter demonstating periodical variations. 
Changing impact of the large-scale atmospheric circulation on the regional climate variability of the Baltic Sea in winters 1950/51-2020/21
Authors: Lehmann Andreas , Post Piia
Published: March 2022

A detailed assessment of climate variability of the Baltic Sea area for the period 1958-2009 (Lehmann et al. 2011) revealed that recent changes in the warming trend since the mid-1980s, were associated with changes in the large-scale atmospheric circulation over the North Atlantic. The analysis of winter sea level pressure (SLP) data highlighted considerable changes in intensification and location of storm tracks, in parallel with the eastward shift of the North Atlantic Oscillation (NAO) centres of action. Additionally, a seasonal shift of strong wind events from autumn to winter and early spring existed for the Baltic area. Lehmann et al. (2002) showed that different atmospheric circulation regimes force different circulation patterns in the Baltic Sea. Furthermore, as atmospheric circulation, to a large extent, controls patterns of water circulation and biophysical aspects relevant for biological production, such as the vertical distribution of temperature and salinity, alterations in weather regimes may severely impact the trophic structure and functioning of marine food webs (Hinrichsen et al. 2007). To understand the processes linking changes in the marine environment and climate variability, it is essential to investigate all components of the climate system, including large-scale atmospheric circulation. Here we focus on the changes/shifts in the large scale atmospheric conditions and their impact on the regional scale variability over the Baltic Sea area for the period 1950-2021. This work extends the previous studies which focused on the response of the Baltic Sea circulation to climate variability for the period 1958-2008 (Lehmann et al. 2011, Lehmann et al. 2014). Now extended time series of ECMWF ERA 5 reanalysis for 7 decades are available, highlighting recent changes in atmospheric conditions over the Baltic Sea. The main focus of this work is to identify predominant large scale atmospheric circulation patterns (climate regimes) on a monthly/seasonal time scale influencing the regional atmospheric circulation over the Baltic Sea area. Furthermore, long-term changes on the annual to decadal time scale will also be investigated.
Unsupervised classification identifies coherent thermohaline structures in the Weddell Gyre
Authors: Jones Dan(i) , Sonnewald Maike , Rosso Isabella , Zhou Shenjie , Boehme Lars
Published: March 2022

The Weddell Gyre is a dominant feature of the Southern Ocean and an important component of the climate system; it regulates air-sea exchanges, controls the formation of deep and bottom water, and hosts upwelling of relatively warm subsurface waters. It is characterized by extremely low sea surface temperatures, active sea ice formation, and widespread salt stratification that stabilizes the water column. Studying the Weddell Gyre is difficult, as it is extremely remote and largely covered with sea ice; at present, it is one of the most poorly-sampled regions of the global ocean, highlighting the need to extract as much value as possible from existing observations. Thanks to recent efforts of the EU SO-CHIC project, much of the existing Weddell Gyre data, including ship-based CTD, seal tag, and Argo float profiles, has been assembled into a coherent framework, enabling new comprehensive studies. Here, we apply unsupervised classification techniques (e.g. Gaussian Mixture Modeling) to the new comprehensive Weddell Gyre dataset to look for coherent regimes in temperature and salinity. We find that, despite not being given any latitude or longitude information, unsupervised classification algorithms identify spatially coherent thermohaline domains. The highlighted features include the Antarctic Circumpolar Current, the central Weddell Gyre, and the Weddell-Scotia confluence waters; we also find potential signatures of the inflow of Weddell Deep Water, the intrusion of Circumpolar Deep Water into the gyre, and export pathways of Antarctic Bottom Water. We show how varying the statistical, machine learning derived representations of the data can reveal different physical structures and circulation pathways that are relevant to the delivery of relatively warm waters to the higher-latitude seas and their associated ice shelves.
Regional slope stability simulations: recent advances in root reinforcement modelling
Authors: Masi Elena Benedetta , Segoni Samuele , Tofani Veronica
Published: March 2022

Literature has been widely enriched lately by results of research on the effects of vegetation on slope stability. The abundant research carried out in the field arose from different purposes: many works were performed with the finality of developing slope stability models and improving their capability of represent the soil behavior, while for many others, the priority was deepening the knowledge on the vegetation effects for bioengineering purposes. All those studies have in common the consequences of having confirmed, deepened, and expanded our knowledge on the subject, in some cases exploring some aspects not considered in the past. Some authors focused on certain plant species, other on the influence of the forest management, still others on the effect of the moisture gradient and wildfires, exploiting the numerical modelling and/or the field work.

The present work aims to summarize the most recent studies about the vegetation effects in slope stability dynamics, focusing on the root reinforcement effect and its parameterization into slope stability models: the evaluation of root reinforcement in wide areas is analyzed with reference to the most recent studies; studies dealing with development of slope stability models that consider root reinforcement are reviewed, followed by works on the influence on slope stability of some plant species, forest management techniques, wildfires and moisture gradients.

The vast spatial and temporal variability characterizing the root reinforcement still represents an open challenge for research in distributed slope stability modelling of wide areas and every new research in the field is much needed. The results of the studies conducted to assess the root reinforcement impact of different plant species highlighted the high species-specific character of the parameter. That points out the importance to pursue the study of new plant species root reinforcement impacts as well as already studied plant species, but in different environmental conditions. The impact of forest structure disturbances due to sylviculture or wildfires on root reinforcement emerged as significative and further studies are therefore needed in this direction. Lastly, some recent works pointed out that soil moisture has a significant control on root tensile strength.