i) Within the framework of 3D resistive MHD, we simulate the formation of a plasma jet with the morphology, upward velocity and timescale formation similar to those expected for Type II spicules as described in González-Avilés et al. (2018a). ii) In this paper we analyze the transverse displacements and rotational type motion of the jet. iii) We calculate time series of the velocity components in different points near to the jet for various heights and find transverse oscillations in agreement with spicule observations. iv) By analyzing temperature isosurfaces, we find that the line-ofsight (LOS) is approximately perpendicular to the jet axis. v) The jet shows a red-blue shift pattern caused by rotational motion

The Stratospheric Aerosol and Gas Experiment operating on the International Space Station (SAGE III/ISS) is an occultation instrument that retrieves aerosol extinction and ozone, water vapor, and other trace gas concentrations. Water vapor in the stratosphere plays a significant role in ozone depletion and global temperature regulation making it an important species to monitor. The new SAGE III/ISS instrument provides high quality, vertically resolved profiles of water vapor throughout the stratosphere and upper troposphere. A discussion is presented on the sensitivity of the SAGE III/ISS instrument to water vapor and provide an early evaluation of the retrieved profiles.

Extreme weather and migratory events have been topics of great interest for decades. More recently, a debate has emerged whether the human impact of climate change can lead to armed conflict, and how conflict and extreme climate events interact in inducing large-scale displacement. This paper explores the relationship between conflict and displacement in the context of droughts and floods across Somalia, a country in the East Africa region, in which the population has historically been using migration as coping strategy for the effects of recurring climatic extremes and socio-economic uncertainties. Since 2015, Somalia has been affected by a humanitarian crisis, paired with on-going conflict, which subsequently reduced resilience of its population. Applying panel econometric methods to monthly within-country migration observations from 18 regions together with spatio-temporal conflict and weather data, this paper quantifies the impacts of conflict and extreme weather events on within-country displacement over the period of 2016 to 2018. It combines and analyses conflict-, drought- and flood-related displacement data from the UNHCR-led Protection & Return Monitoring Network (PRMN), disaggregated conflict data from the Armed Conflict Location & Event Data Project (ACLED) with gridded climate estimate data. Empirical evidence suggests significant interaction effects between conflict and extreme weather events on migration, where pre-existing conflict conditions act as accelerators of climate-induced displacement.

Unsaturated fractured aquifer systems offer a domain for complex gravity-driven flow dynamics leading to the development of preferential flow along fracture networks that often strongly contributes to rapid mass fluxes. This behaviour is difficult to recover by volume-effective modeling approaches (e.g. Richards equation) due to the non-linear nature of free-surface flows and mass partitioning processes at unsaturated fracture intersections. The application of well-controlled laboratory experiments enables to isolate single aspects of the mass redistribution process that ultimately affects travel time distributions across scales. We use custom-made acrylic cubes (20 cm x 20 cm x 20 cm) in analogue percolation experiments to create simple fracture networks with single or multiple horizontal fractures. A high precision multichannel dispenser produces gravity-driven free surface flow (droplets; rivulets) at flow rates ranging from 1 ml/min to 5 ml/min. Hereby, total inflow rates are kept constant while the fluid is injected via 15 (droplet flow) or 3 inlets (rivulet flow) to reduce the impact of erratic flow dynamics. Normalized fracture inflow rates (Q_f/Q_0) are calculated and compared for aperture widths d_f of 1 mm and 2.5 mm. A higher efficiency in filling an unsaturated fracture by rivulet flow observed in former studies can be confirmed. The onset of a capillary driven Washburn-type flow is determined and recovered by an analytical solution. In order to upscale the dynamics and enable the prediction of mass partitioning for arbitrary-sized fracture cascades a Gaussian transfer function is derived that reproduces the repetitive filling of fractures, where rivulet flow is the prevailing regime. Results show good agreement with experimental data for all tested aperture widths.

Experimental study of the phase and amplitude observations of sub-ionospheric very low and low frequency signals is performed to analyze the response of the lower ionosphere during the August 21, 2017 total solar eclipse in the United States of America. Three subionospheric wave paths have been investigated. The length of the paths varied from 2200 to 6500 km, signal frequencies were 21.4 kHz, 25.2 kHz and 40.8 kHz. Two paths crossed the region of total eclipse and the third path was in the region of 40-60% of obscuration. None of the signals revealed any noticeable amplitude changes during the eclipse while negative phase anomalies (from -35° to -95°) were detected for all three paths. It was shown that the effective reflection height of the ionosphere in low and middle latitudes has been increased by 3.5-5 km during the eclipse.

Random and small-scale subsurface heterogeneities in velocity and/or density scatter the seismic wavefield when they have scale lengths on the order of the seismic wavelength. Seismic scattering is considered the origin of coda waves. Such inhomogeneities have an important effect on propagating waves, as they generate traveltime and amplitude fluctuations and may be the cause of attenuation or excitation of secondary waves. Understanding the effect of small-scale heterogeneities on the seismic wavefield is important for the characterization of the seismic source (e.g. source parameters of underground nuclear explosions) and to improve our knowledge of the Earth’s structure along the raypath. Several approaches and methods have been suggested to study the scattering of seismic waves and characterise subsurface heterogeneities. Here, we apply a combination of the analysis of the incoherent wavefield component and the coda decay with time to a dataset of over 350 teleseismic events (over 20000 traces) recorded at three seismic arrays (Warramunga, Alice Springs and Pilbara) in Australia. This combination allow us to obtain a series of parameters (correlation length, RMS velocity fluctuations of the heterogeneities and thickness of the scattering layer) that give us a measure of the spatial scale and the magnitude of the heterogeneities present in the lithosphere beneath the arrays. This is the first time such a large dataset is used for a study of these characteristics. Our new results show similar structures and scattering strength for Alice Springs and Warramunga, while revealing a different tectonic signature and stronger scattering in the case of Pilbara, possibly caused by the different thicknesses of crust and lithosphere between these regions and its different tectonic history. These stochastic models of the lithosphere are the first step in the development of a technique analogous to adaptive optics which, in this case, aims at removing the effect of the small-scale, near receiver structure from recorded wavefields, thus enabling us to improve our source characterization and to more clearly image the Earth’s interior.

Groundwater fluoride is the major cause of the endemic fluorosis. Global fluorosis data indicate that that granitic aquifer which fractures controlled hydrology is highly susceptible to contaminate groundwater with high fluoride. Till date there has not been any sincere effort to understand the type of granitic aquifer based on the different type of the granites and their fluoride content. The present paper assesses the different types of granites and their fluoride content. Dissolution of fluoride from these rock types are the major source of high fluoride contamination in the groundwater. The granitic aquifers are also dominated by fracture control hydrology which enhances the chances of rock water interaction and dissolution of fluoride. The mineralogy of the rocks is also favorable due to the presence of biotite and muscovite which are found to have high affinity to donate fluoride during rock water interaction as shown by the following equation. KAl2[AlSi3O10]F2+2OH- = KAl2[AlSi3O10]OH-+2F- (Muscovite) KMg3[AlSi3O10] F2+2 OH- = KMg3[AlSi3O10]OH-+2F- (Biotite) Delineation of the type of aquifer and the geochemistry of the granitic rocks needs to assess to understand the geogenic causes of fluoride in the granitic aquifer along with the water chemistry (pH>8) which enhances the rate of dissolution of fluoride during rock water interaction. Further estimation can be made by the application pf isotopic data particularly 18O, 2H, 3H, 34S isotope which can quantitatively estimate the sources of fluoride and contribution from different sources as well as rock water interaction time.

High concentration of fluoride in the groundwater is observed to be associated with granitic aquifers as well as near phosphate mines around the globe. The present work is a hydrogeological study of the ground water of Beldih phosphate mines in India. Being located in the Singhbhum shear zone the area has a complex tectonic history and is dominated by phosphate, alkali granites, amphibolites, and granitic gneiss with higer abundance of fluoride bearing minerals like apatite and biotite. Total of 12 water samples were collected for a preliminary study to assess the spatial variation of fluoride in ground water and surface water with an aim to understand the effect of phosphate mines in elevating fluorosis in adjoining areas. The groundwater chemistry shows a trend that the concentration of fluoride and nitrate gets elevated as we approach towards the open cast phosphate mines. From the spatial observation combined with the water chemistry and geology it is evident that the apatite dissolution is the prime cause of the elevation in fluoride concentration. However presence of iron in the lithology controls the fluoride level to some extent. Since the area is effected with high fluorosis its can be concluded that the groundwater geochemistry along with the air borne fluoride present in the phosphate dust are the major cause of the fluorosis. The exploration of phosphate must be carried out with out most environmental care and the mitigation of post mining effect should be planned before mining operation. Fluorosis is an irreparable health hazard and a major geohealth concern that has already affected a large amount of population.

Transmission muography is an expanding technique based on the attenuation of the natural-occurring cosmic muons flux due to the opacity of the medium to obtain the distribution of density around the detector. The current work introduces the technology developed by the Temporal Tomography of the Densitometry by the Measurement of Muons (T2DM2) collaboration. The MUST2 camera leans on a thin time projection chamber read by a resistive Micromegas. This new tool presents interesting distinctive features, allowing a wide angular acceptance of the detector with a low weight and volume, well adapted for confined spaces or underground operation. The results obtained from field measurement campaign carried out at the dam overlooking the village of Saint-Saturnin-les-Apt (South-East of France) are presented. The influences of (i) the host rock body of the barrage and dam’s structure, (ii) the temporal water level variations of the reservoir and (iii) the effect of the temperature on the muons flux measurements are discussed The main challenge that faces the project is that the muon trajectory reconstruction algorithm cannot infer the arrival angles for a non-negligible number of detected events, with the subsequent loss of information. The data collected during the campaign of measurements, should help improving the algorithm’s robustness and reconstruction efficiency. Field transportability and the capability to perform long-term out-of-lab measurements have been demonstrated. The successful proof-of-concept trial makes the MUST2 camera a valuable candidate for transmission muography purposes, particularly in challenging available volume scenarios. The next phase of the T2DM2 project aims at imaging and monitoring the hydrodynamics across the unsaturated zone of the Fontaine-de Vaucluse aquifer. To do so, a network of 20 autonomous detectors will be constructed and deployed within the facilities of the Low Background Noise Laboratory of Rustrel (LSBB), France. The privileged emplacement of the LSBB allows the access to both the surface and to a network of 4 km of underground galleries with depths ranging from 0 to 518 m.

The Campi Flegrei caldera is well known for being one of the most volcanically risky areas in the world. Notably, it has an extension of about 120 square km, and 40% of its area is submerged forming the Gulf of Pozzuoli. A remarkable expression of the local volcanic dynamics is the slow ground displacement across the whole caldera. This peculiarity makes this area a natural laboratory for developing and testing innovative methods to assess seafloor deformation. Until 2008 no seafloor deformation measurements were performed in the submarine part of the caldera, while ground deformation measurements have been extensively and routinely acquired on land since the beginning of the last century. In 2008 CUMAS, a multisensor prototype buoy, was deployed in the Gulf of Pozzuoli within a program of extension of the land-based geophysical monitoring network toward the marine sector of the caldera. CUMAS, placed at 2.5 km from the coast in about 100 m water depth, was able to acquire the first sea floor deformation measurement in the submerged portion of the caldera. In 2016, a new marine monitoring network, MEDUSA, was deployed to achieve a larger coverage of the Gulf of Pozzuoli incorporating CUMAS. MEDUSA marine network presently consists of four instrumented buoys hosting geodetic GPS receivers on the top. Moreover, each buoy is connected through a cable to a seafloor module equipped with oceanographic and geophysical sensors including a bottom pressure recorder (BPR). One of the buoys is also equipped with a tide gauge. Using the GPS, BPR and tide gauge data provided by MEDUSA, we were able to assess the seafloor deformation field in the Gulf of Pozzuoli for the first time: we estimated a seafloor vertical displacement of about 10 cm ±1 cm over a period of twenty months embracing 2016 to 2018. The presentation is aimed at giving details about the design of MEDUSA and about the multiparameter data analysis leading to the deformation field estimation.

Researcher Ridge (RR) is a 400km long, WNW-ESE oriented chain of volcanic seamounts, located on ~20 to 40 Ma old oceanic crust on the western flank of the Mid-Atlantic Ridge (MAR) at ~15°N. RR remained nearly unstudied, and thus its age and origin are currently unclear. At roughly the same latitude, the MAR axis is bathymetrically elevated and produces geochemically enriched lavas (the well-known 14°N MAR anomaly). This study presents 40Ar/39Ar age data, major and trace elements, and Sr-Nd-Pb-Hf isotopic compositions of volcanic rocks dredged from several seamounts of the RR and along the MAR between 13-14°N. The results reveal that RR lavas have geochemically enriched ocean island basalt (OIB) compositions ([La/Sm]N=1.7-5.0, [Ce/Yb]N=1.58-11.3) with isotopic signatures (143Nd/144Nd = 0.51294-0.51316, 206Pb/204Pb = 19.14-19.93, 176Hf/177Hf = 0.28307-0.28312) trending to or overlapping the ubiquitous FOZO (Focal Zone, e.g., Hart et al., 1992, Science 256) mantle composition. Major and trace element characteristics denote that RR lavas formed by small degrees of melting from a deep source in the garnet stability field and experienced high pressure fractionation beneath a lithospheric lid. Although the sparseness of samples suitable for 40Ar/39Ar dating prevents establishing a clear age progression for the seamount chain, one well constrained basalt groundmass age of 28.75 ± 0.14 Ma (2σ) for one seamount near the western end of RR indicates that this volcano formed ~11 Ma later than the underlying lithosphere. Taken together, RR is interpreted as a hotspot track, albeit formed by a relatively weak melting anomaly. Compared to RR, the lavas from the 14° N MAR anomaly have slightly less enriched compositions, exhibiting enriched (E)-MORB compositions ([La/Sm]N=1.81-2.29). Their isotopic ratios largely overlap with the RR compositions, thus suggesting a genetic relationship. We therefore propose that the enigmatic 14°N MAR anomaly is caused by deflection of upwelling RR plume material towards the approaching (westward migrating) MAR, causing the production of E-MORBs with nearly similar isotopic compositions to the RR lavas. Once the plume was captured by the spreading ridge, off-axis hotspot track volcanism ceased, resulting in a 300 km wide gap of seamount formation between the eastern end of RR and the MAR.

Mapping absolute P-wavespeeds in the Canadian and Alaskan mantle will further our understanding of its present-day state and evolution. S-wavespeeds are relatively well constrained, especially across Canada, but are primarily sensitive to temperature while complimentary P-wavespeed constraints provide better sensitivity to compositional variations. One technical issue concerns the difficulties in extracting absolute arrival-time measurements from often-noisy data recorded by temporary seismograph networks. Such processing is required to ensure that regional Canadian datasets are compatible with supplementary continental and global datasets provided by global pick databases. To address this, we utilize the Absolute Arrival-time Recovery Method (Boyce et al., 2017). We extract over 180,000 new absolute arrival-time residuals from seismograph stations across Canada and Alaska that include both land and ocean bottom seismometers. We combine these data with the latest USArray P-wave arrival-time data from the contiguous US and Alaska. Using an adaptively parameterised least-squares tomographic inversion we develop a new absolute P-wavespeed model, with focus on Canada and Alaska (CAP21). Initial results suggest fast wavespeeds characterise the upper mantle beneath eastern and northern Canada. A sharp transition between the slow wavespeeds below the North American Cordillera and the fast wavespeeds of the stable continental interior appears to follow the Cordilleran Deformation Front (CDF) in southwest Canada. Slow wavespeeds below the Mackenzie Mountains may extend further inland of the CDF in northwest Canada. In Alaska, CAP21 illuminates both lithospheric structure and the along strike morphology of the subducting slab. The newly compiled data may also improve resolution of subducted slab remnants in the mid-mantle below the North American continent, crucial to help constrain the formation of the Alaskan peninsular at ≥50Ma.

The large-scale electric field in the inner magnetosphere is a key driver of many processes and the dynamics of magnetospheric plasmas. During geomagnetic storms, the enhanced convection electric field is responsible for eroding the plasmasphere and for moving the inner edge of the plasma sheet earthward. In this presentation, we show the preliminary results of an examination of the distribution and variations of the inner magnetospheric quasi-static electric field as measured by the Electric Field and Waves (EFW) instruments onboard the twin spacecraft of the Van Allen Probes mission. We investigate the role that the electric field plays in plasmasphere erosion and plasma sheet access to the inner magnetosphere by analyzing the electric field measurements in conjunction with cold plasma density and plasma sheet particle flux measurements. Since the coupling between plasma populations in the magnetosphere is inherently related to the electric field, we expect that the combined measurements of the electric field and plasmas will enhance our understanding of the physical processes that drive the magnetospheric dynamics.

The ease with which radionuclide moves through the environment and is taken up by plants and animals is determined by its speciation and site-specific environmental characteristics. The peculiarities in climate, geomorphology and 137Cs speciation in the fallout were demonstrated to lead to differences in migration rates of 137Cs in the environment and rates of its natural attenuation. It has been revealed that in the exclusion zone the Fukushima-derived 137Cs is strongly bound to soil and sediment particles, which reduces potential bioavailability of this radionuclide. Substantial fraction of the deposited 137Cs on soil of the exclusion zone were found to be incorporated in hot glassy particles (“Cs balls”) insoluble in water. These particles are decomposing in the environment essentially slower as compared with Chernobyl derived fuel particles. Wash-off from the slopes of contaminated catchments and river transport are key long-term pathways for radionuclide dispersal from contaminated areas after the Fukushima accident. The climate conditions for the Fukushima Prefecture of Japan are characterized by higher annual precipitation (1300-1800 mm/year) with maximum rainstorm events during typhoon season. Typhoons Etou in 2015 and Hagibis in 2019 demonstrated the substantial redistribution of 137Cs on river watersheds and floodplains and in some cases natural self-decontamination occurred. Steep slopes of Fukushima catchments are conducive to higher erosion and higher particulate r-Cs wash-off. Irrigation ponds in Okuma and Futaba towns demonstrated persistent behavior of 137Cs similar to the closed lakes in Chernobyl, its concentration is decreasing slowly and showing regular seasonal variations: the 137Cs concentrations tend to grow in the summer and decrease in the winter.

Saline endorheic lakes play a crucial role in ecological regulation and biodiversity conservation in semi-arid regions. They provide a wide range of ecosystem services such as habitat for aquatic life and migratory birds, water supply, mineral extraction, and recreation. Although saline lakes are critical to ecological health and human wellbeing, they are being shrunk at alarming rates in recent decades, representing some of the most threatened ecosystems in the world. Factors contributing to lake degradation are directly linked to the expansion and intensification of agriculture in the 20th century and its intertwined effect with global warming. However, quantifying the relative contribution of climate variability and anthropogenic stressors in water budget dynamics of the lakes is challenging. Hydrologic processes of highly managed agricultural landscapes are complex and the lack of spatial data in endorheic basins with transboundary water issues further contribute to this problem. In this study, we developed a modeling framework that integrates the Soil and Water Assessment Tool (SWAT) simulations with seasonal trend decomposition by LOESS (STL), residual analysis for anomaly detection, and time series clustering, to identify the major drivers of lake trend and seasonal shrinking patterns. This modeling framework was applied to the Salton Sea Basin (SSB), host of the largest inland lake in California. Salton Sea’s water level has declined by 32% over the last 25 years, causing a massive bird and fish die-off, and a regional asthma crisis due to the spreading of toxic dust from the exposed playa. Results suggest that decreases in Colorado River allocation are causing the lake to shrink, not changes in the irrigation efficiency or the climate regime as commonly believed. Our results are expected to assist decision-makers with a robust modeling tool to evaluate the environmental tradeoffs in formulating and implementing timely adaptation and mitigation strategies across the SSB while minimizing their economic consequences.

The transition from active to passive continental margin of the South China Sea (SCS) is usually inferred to occur in the Late Mesozoic to Early Cenozoic. However, it is less known about the tectonic characteristics of active continental margins before the Late Mesozoic, which hampers the recognition of integral evolution of the SCS. The International Ocean Discovery Program (IODP) site U1504 has sampled greenschist facies mylonite from the basement in the Outer Margin High of the northern SCS continental margin, which potentially record the Mesozoic and Cenozoic tectonic evolution of the SCS region. The microstructure has identified two episodes of deformation in the mylonite, namely early ductile and late brittle deformation, but without age constraints. Here, we further identify three episodes of carbonate veins (pre-mylonite, syn-mylonite and post-mylonite) in the greenschist facies mylonite according to the intersecting relationship between the veins and the mylonite foliation. Then we select 10 carbonate samples for in situ U-Pb dating, and obtain three accurate ages. The pre-mylonite carbonate veins are dated to 210 ± 20 Ma and 195 ± 32 Ma, respectively, which might denote the age of the protolith clast. The age of the syn-mylonite carbonate vein is 135 ± 12 Ma. But for the post-mylonite carbonate veins, no effective age was obtained using U-Pb dating method. Post-mylonite carbonate veins and late brittle fractures were formed at the same time, and the formation environment is similar to the overlying Late Eocene bioclastic limestone. Therefore, combining the microstructure, geochemistry and seismic profile, we speculate that the post-mylonite carbonate veins and brittle fractures may be formed during the Early Cenozoic rifting. These dating ages of the three episodes of carbonate veins suggest that the mylonite records at least two main periods of continental extension in the SCS region since the Early Cretaceous. In reference to the Mesozoic tectonic settings, we infer that, due to the slab rollback of the subducting paleo-Pacific, the SCS continental margin started significant extension during the Early Cretaceous as shown by the ductile deformation of the mylonite. In the Early Cenozoic, the mylonite was exhumated to the seafloor along with further continental extension, and weak brittle deformation occurred in the mylonite. Therefore, the Early Cretaceous extension of the SCS active continental margin may have a certain promotion effect on the rupture of the passive continental margin in the Cenozoic. Keywords: Greenschist facies mylonite; Carbonate U-Pb dating; Continental margin of the SCS; Early Cretaceous; IODP 368

Substantial progress on machine learning (ML) models and graphical processing units (GPUs) has stimulated emerging research in applications of ML to earth science. As snow is a vital component of the global hydroclimate system, precise snowpack prediction is of considerable value for science and society. In this work, we have trained three different ML models (LSTM, CNN and Attention) to predict daily snow water equivalent (SWE) with both dynamic and static features in the Western Contiguous United States from Snow Telemetry (SNOTEL) observations. Dynamic features include precipitation, minimum and maximum temperature, minimum and maximum relative humidity, specific humidity, solar radiation and wind velocity. Static features are latitude, longitude, elevation, diurnal anisotropic heating (DAH) index and topographic radiative aspect (TRASP) index. This choice of features allows us to produce high-resolution maps of regional SWE for a given set of input meteorological conditions. The importance and the sensitivity of input variables will be tested by several explainable AI methods including feature permutation and integrated gradient. The ML-based dataset is further up-sampled and compared with the 4km gridded SWE dataset from the National Snow & Ice Data Center (NSIDC), which is from a physical-based model. Future SWE estimates are also produced under climate conditions projected by CMIP class models, along with associated uncertainty estimates based on our sensitivity analysis. The ML models are demonstrated to be a fast and accurate method of producing high-resolution SWE estimates with minimal computing power.

The IGS contribution to ITRF2020, based on the third IGS reprocessing campaign (repro3), comprises daily position estimates for 1905 globally distributed GNSS stations. As an essential step of the ITRF2020 preparation, a detailed analysis of the IGS repro3 station position time series has been carried out, including identification of offsets, modeling of post-seismic displacements, confrontation with deformation predicted by geophysical loading models, and characterization of systematic and random errors. This presentation covers the different aspects of this analysis, the methods used and the lessons learned.