bluuebunny/crossref_metadata_2025 huggingface dataset:
Constraining global dynamic topography using a revised observational database
Authors: Holdt Megan , White Nicky , Stephenson Simon
Published: March 2022

Earth’s topography is supported by both crustal and sub-crustal density variations. Dynamic topography results from the vertical displacement of the Earth’s surface due to processes operating within the mantle. Thus, isolating and quantifying observable dynamic topography can yield valuable information about mantle dynamics. An observationally-based approach can be used to investigate dynamic topography by calculating residual depth anomalies in the oceanic realm and residual topographic anomalies on the continents. To constrain the residual topographic contribution that arises from sub-crustal processes it is necessary to correct for crustal and sedimentary loading. We identify and correct for both forms of loading by exploiting a variety of seismologic datasets that include seismic reflection profiles, wide-angle/refraction surveys and receiver functions. We present a revised global compilation of oceanic residual depth measurements (n = 10,846) and continental residual topographic measurements (n = 3,897). This compilation represents a significant improvement in terms of the quantity and spatial distribution of measurements. In the oceanic realm, the correction methodology has been revised in two ways, which has improved resolution and accuracy. First, the crustal correction now accounts for variations in bulk density as a function of crustal thickness. Secondly, the quartz and clay content of the sedimentary column has been adjusted, which improves the quality of the sedimentary correction. The revised global compilation is used to generate a spherical harmonic representation of observable dynamic topography out to degree 40 (i.e. ~ 1000 km). The resultant power spectrum demonstrates that dynamic topography varies linearly with inverse wavenumber. Our global results are consistent with independent geologic markers of uplift and subsidence.
Investigation of the features of heavy ion acceleration events in the Jovian magnetotail using Juno/JEDI data
Authors: Moutsiana Georgia , Clark George , Gkioulidou Matina , Daglis Ioannis , Mauk Barry
Published: March 2022

Our solar system contains a variety of planetary magnetospheres, which are known to be very efficient accelerators of charged particles. The energization processes of magnetotail plasma populations are thought to share similarities among the various magnetospheres. In the present study, we investigate the characteristics of ion acceleration processes in the Jovian magnetosphere, which contains a variety of ion species with different charge states, resulting in a diverse set of acceleration-relevant factors that can be tested. In this study, we use magnetic field data from the MAG instrument, and energetic ion data from the JEDI instrument onboard the Juno mission, in order to investigate the energization of hydrogen (~50 keV to ~1 MeV), oxygen (~170 keV to ~2 MeV) and sulfur (~170 keV to ~4MeV) ions during dipolarization events in the Jupiter’s magnetosphere. Results of our study are a first step towards a comparative analysis of the energization processes around the dipolarization events in the Jupiter’s and Earth’s magnetotails. 
Assessing the Effectiveness of SLM Measures in Restoring Forest Ecosystem Services Disturbed by Forest Fires
Authors: Faria Beatriz , Nunes João , Wu Jinfeng , Baartman Jantiene , Prats Sergio , Dias Luís
Published: March 2022

Forest fires strongly disturb important hydrological ecosystem services, such as the provision of clean water, the regulation of water flows, erosion prevention and soil conservation, which can ultimately lead to public health problems for communities. Post-fire management measures can be very expensive and their effectiveness depends on many factors, i.e., the measures themselves, the selection of the target areas and extent of their application.

This study aimed at assessing which combination(s) of soil and water conservation (SWC) measures are the most effective in restoring forest ecosystem services, by preventing soil erosion and stream water contamination.

The OpenLISEM v5.97 model was applied, calibrated, and validated for the Odiáxere catchment in southern Portugal, using pre-fire and post-fire data gathered for a wildfire in 2003. The model is able to simulate runoff, sediment yield and total erosion for conditions before and after the fire. SWC measures were parameterized and tested in the model; these include mulching, riparian buffers, fuel breaks, prescribed fires, and erosion barriers, such as geotubes, contour-felled logs and contour bunds. Multiple application strategies for these measures are also being designed.

The results obtained from the model are being further assessed using a multiple criteria analysis (MCA), including criteria such as measure effectiveness (in decreasing erosion and sediment yield), application costs, benefits besides soil and water conservation, and other relevant factors. 

Finally, the results will be translated to more practical findings, that facilitate the implementation of the selected measures. Preliminary results showed that only some SWC measures should be implemented carefully in target spots to achieve the more effective solutions, useful information for forest managers and local administrators.

Keywords: forest fires, soil erosion, SWC measures, OpenLISEM.
Mapping field-scale soil moisture and its spatial variability across the United States using SMAP-HydroBlocks
Authors: Vergopolan Noemi , Sheffield Justin , Chaney Nathaniel W. , Pan Ming , Beck Hylke E. , Ferguson Craig R. , Torres-Rojas Laura , Eigenbrod Felix , Crow Wade , Wood Eric F.
Published: March 2022

Soil moisture (SM) varies widely in space and time. This variability influences agriculture, land-atmosphere interactions and triggers hazards, such as flooding, landslides, droughts, and wildfires. Yet, current observations are limited to a few regional in situ measurement networks or coarse-scale satellite retrievals (9–36-km resolution). As a result, besides site-specific studies, little is known on how SM varies locally (1–100-m resolution). Consequently, quantifying the impact of this variability remains a critical and long-standing challenge in hydrology. This presentation introduces SMAP-HydroBlocks – a novel 30-m resolution SM dataset (2015–2019) that combines hyper-resolution land surface modeling, satellite, and in-situ observations over the United States. Using this data, we reveal the striking variability of local-scale SM across the United States. By mapping the SM spatial variability and its persistence across spatial scales, we show the complex interplay between the landscape and hydroclimate and how this variability is highly scale-dependent. Results show that up to 80% of SM spatial variability information is lost at the 1-km scale, with further losses expected at the scale of current monitoring systems (5–25-km). This high degree of SM variability has a critical influence on freshwater and land ecosystem dynamics. By mapping its spatial variability locally, we provide a stepping-stone towards understanding SM-dependent hydrological, biogeochemical, and ecological processes at local (and so far unresolved) scales.
Mediterranean Outflow Water characteristics in the Northeast Atlantic in 2019 and 2021.
Authors: Bocherikova Irina , Krechik Viktor , Kapustina Maria , Dvoeglazova Nadezhda
Published: March 2022

The characteristics of Mediterranean Outflow Water (MOW) in the Northeast Atlantic were obtained during the 43rd cruise of the R/V Akademik Nikolaj Strakhov (October 2019) and the 59th cruise of the R/V Akademik Ioffe (September 2021) using CTD measurements. MOW is transformed Mediterranean Sea Water flowing down the slopes of the Strait of Gibraltar into the Gulf of Cadiz, where it mixes with underlying North Atlantic Central Water. MOW spreads at water depths between 500–1500 m in the eastern North Atlantic and is characterized by higher temperatures and salinities than other ambient water masses. In 2019 and 2021 MOW was located at depths of about 700–1500 m. The temperature in the core of MOW was in the range of 9.5–11.5 °C, while in 2019 both temperature and salinity were higher than in 2021. The salinity in the core was 36.15 psu in 2019 and 36.08 psu in 2021. The comparison of MOW characteristics obtained in 2019 and 2021 with data obtained in cruises in 1993, 2001 and 2005 from the CLIVAR and Carbon Hydrographic Data Office (https://cchdo.ucsd.edu/) showed that the maximum salinity values were observed in September 1993 and reached 36.17 psu. The minimum value of this parameter in the core of MOW was recorded in April 2001 and was 36.03 psu. According to the data of the 1993–2019 expeditions, the maximum salinity was noted at a depth of 1000–1100 m. In 2021, the core of MOW was slightly deeper — about 1150 m. The temperature in the MOW core in all studied years was in the range of 11.1–11.3 °C, with the exception of 2001, when the maximum temperature in the core was about 10.9 °C.

Acknowledgements

The financing of the expedition and the primary processing of the data obtained on the 59th cruise of the R/V Akademik Ioffe were carried out at the expense of the state assignment of IO RAS № 0128–2021–0012. The analysis and interpretation of the data were supported by the Russian Science Foundation (project no. 21–77–20004).
A comparison of numerical and analogue models of subduction initiation at passive margins.
Authors: Auzemery Antoine
Published: March 2022

Modelling studies show that subduction initiation requires failure of the load-bearing crustal and mantle layers and critically depends on the buoyancy and strength contrast within the lithosphere. Such findings suggest that the probability of subduction initiation must increases in the vicinity of continental margins. Yet, direct evidence for subduction initiation at passive margin is scarce and the mechanisms of subduction initiation in this particular setting remains a recurrent and long-standing unresolved question. Therefore, our study focuses on the kinematic and rheologic key parameter combinations relevant for the formation of a subduction zone, with the aim of identifying the feasibility of subduction initiation at a passive margin setting. To challenge the existing limits and discriminate processes that fit conditions for subduction nucleation, we compare and combine analogue and numerical modelling techniques. In this work, numerical modelling allows exploring temperature driven feedback mechanisms whereas analogue modelling allows for mapping characteristic length scales of deformation against the mode of subduction initiation. Overall, model results highlight that the convergence rate, the strength contrast at the margin as well as the degree of crust-mantle coupling control the development of a shear zone at the base of the crust, and the propagation of deformation into the mantle lithosphere. In addition, comparison between analogue and numerical modelling results infers that shear heating, weak sediments, magmatic heterogeneities or a serpentinite mantle wedge, are important parameters for the development of a self-sustaining subduction zone. The relevance of the modelling results is demonstrated by comparing length-scales of deformation with observations from inverted continental passive margins and orogenic systems, such as the Alps and Dinarides. Models predict that primary response of the lithosphere to compression is by folding and that tectonic structures and early-stage length-scales of deformation can be used to predict the likeliness of subduction initiation at a passive margin.
Mercury and methylmercury in the benthic organisms of Admiralty Bay (Antarctica).
Authors: Jarzynowska Małgorzata , Saniewska Dominika , Saniewski Michał , Bałazy Piotr
Published: March 2022

There are only few studies on the concentration of mercury in organisms inhabiting the polar regions, in particular those living in Antarctica. Therefore, it is difficult to accurately illustrate the toxic effects of mercury on the local fauna. The aim of this study was to recognize the concentration of total mercury and methylmercury in organisms inhabiting the Antarctic coastal zone and compare these results with organisms from the Arctic. An attempt was made to determine the potential for mercury and methylmercury to accumulation and biomagnification in the benthic food web depending on the trophic level and the size of the organism. In addition, the effect of melting glaciers on the concentration of total mercury in marine organisms was investigated. The research was carried out on samples of benthic organisms collected directly by divers from the Admiralty Bay during austral summer 2018/2019.The concentration of total mercury and methylmercury was analyzed in 3 representatives of Antarctic benthos - gastropod Nacella concinna, sea urchin Sterechinus neumayeri and starfish Odontaster validus using the method of atomic absorption spectrometry. The obtained results confirmed the existence of processes such as accumulation and biomagnification of mercury in marine organisms from the Admiralty Bay. However, mercury concentration in Antarctic zoobenthos were lower than those measured in the Arctic, as well as methylmercury concentration. The problem of high mercury and methylmercury concentration in organisms inhabiting the polar regions is particularly important due to the characteristics of the local fauna, which is slow metabolism and longevity. In addition, the endemic nature of the Antarctic fauna and the relatively short trophic chain mean that these animals, and especially the organisms at the top of the food pyramid, may be particularly endangered on many contaminants. Research on benthic organisms can be an important part of polar monitoring, due to their relatively limited movement. This study has been performed within the framework of a National Science Center projects No. 2019/33/B/ST10/00290 and No. 2017/27/N/ST10/02230.
Surface energy balance and sublimation of the winter snow cover at 4863 m a.s.l. on Chhota Shigri Glacier moraine (western Himalaya, India) between 2009 and 2020
Authors: Mandal Arindan , Angchuk Thupstan , Azam Mohd Farooq , Ramanathan Alagappan , Wagnon Patrick , Soheb Mohd , Singh Chetan
Published: March 2022

Surface energy balance (SEB) is the most comprehensive way to explain the atmosphere-glacier interactions but requires extensive data. We analyse an 11-year (2009-2020) record of the meteorological dataset from an automatic weather station installed at 4863 m a.s.l., on a lateral moraine of the Chhota Shigri Glacier in the western Himalaya. The study was carried out over the winter months (December to April) to understand the SEB drivers and snow sublimation. Further, we examine the role of cloud cover on SEB and turbulent heat fluxes. The turbulent heat fluxes were calculated using the bulk aerodynamic method, including stability corrections. The net short-wave radiation is the primary energy source. However, a significant amount of energy is dissipated by the turbulent heat fluxes. The cloud cover plays an important role in limiting the incoming short-wave radiation by up to 75%. It also restricts the turbulent heat fluxes by around 50%, consequently less snow sublimation. During the winter period, turbulent latent heat flux contributed the largest (63%) in the total SEB, followed by net all-wave radiation (29%) and sensible heat flux (8%). Dry air, along with the high snow surface temperature and wind speed, favours sublimation. We also observe that strong and cold winds, possibly through mid-latitude western disturbances, impede sublimation by bringing high moisture content in the region and cooling the snow surface. The estimated snow sublimation fraction is 18 to 42% of the total winter snowfall at the study site, indicating that the snow sublimation is an essential parameter in the surface mass balance and hydrological modelling at the high mountain Himalayan catchments.
Drought recovery of southern Andes natural catchments
Authors: Vega-Briones Jorge , Galleguillos Mauricio , de Jong Steven , Wanders Niko
Published: March 2022

Drought causes hydroclimatic stress on terrestrial ecosystems and we see that these effects can have a long duration even when the drought is alleviated. The impacts of a drought are commonly dependent on the severity and duration of the hydrological drought event. At the same time, we see that the recovery from a severe drought is also impacted by catchment characteristics and regional climatology. In this study, we focus on Chile which has frequently experienced multi-drought periods with severe impacts.

In this study, we quantify the recovery of discharge, vegetation productivity (kNDVI), and soil moisture after hydrological droughts to quantify the drought termination (DT) and drought termination duration (DTD). We used the CAMELS-CL data set from 1988-2020 to study drought recovery in natural catchments. Using a composite analysis we obtain the average response of discharge, vegetation, and soil moisture after severe drought events for catchments throughout Chile. We estimate the impact of different explanatory variables and catchment properties from the CAMELS-CL data on DT and DTD using lasso regression for discharge, vegetation productivity, and soil moisture without selecting strongly correlated variables.

Our study demonstrates that the drought recovery of discharge can be explained by local characteristics while these relationships are less pronounced for vegetation and soil moisture droughts. Longer recovery times were found in environments with less precipitation and higher temperatures, with mainly shrub land cover. Shorter recovery times, at higher latitudes with increasing precipitation and lower temperatures under higher vegetation cover. The explanatory variables for discharge DT and DTD are associated with precipitation, potential evapotranspiration, and baseflow, or by a combination of them with catchment characteristics related to storage and release (e.g. land use). To that end, this work can help to identify drought vulnerability in regions where observations are lacking and help to predict drought recovery periods.
Dynamic Topography of the Australian Continent and its Margins
Authors: Slay Philippa , White Nicholas , Stephenson Simon
Published: March 2022

Mantle convection generates transient vertical motion at the surface, which is referred to as dynamic topography. The bulk of topography and bathymetry is isostatically supported by variations in the thickness and density of both the crust and the lithosphere which means that dynamic topography generated by sub-plate density anomalies needs to be isolated from these dominant isostatic signals. Australia’s isolation from plate boundaries and its rapid northwards translation suggest that long-wavelength dynamic topography is primarily controlled by the interplay between plate motion and sub-plate convection. Along the eastern seaboard of Australia, the coincidence of elevated topography, positive long-wavelength free-air gravity anomalies and Cenozoic basaltic magmatism imply that a combination of asthenospheric temperature anomalies and thinned lithosphere generate and maintain regional topography. Distributions of onshore and offshore intraplate magmatism reflect both plate motion and convective instabilities. Compilations of deep seismic reflection profiles, wide-angle surveys and receiver function analyses are used to determine crustal velocity structure across Australia. Residual (i.e. dynamic) topographic signals are isolated by isostatically correcting local crustal structure with respect to a reference column that sits at sea level. The resultant pattern of dynamic topography is consistent with residual bathymetric anomalies from oceanic lithosphere surrounding Australia. Significant positive dynamic topography occurs along the eastern seaboard and in southwest Australia (e.g. Yilgarn Craton). These signals are corroborated by independent geologic evidence for regional uplift.
Stable water isotopes reveal the effects of land use on ecohydrological partitioning in a drought-sensitive mixed land-use catchment 
Authors: Landgraf Jessica , Tetzlaff Dörthe , Dubbert Maren , Soulsby Chris
Published: March 2022

Ecohydrological fluxes in the critical zone are characterised by complex interactions between soils, plants, and the atmosphere. Vegetation and land use therefore play a crucial role in forming the interface between the soil and atmosphere, and spatial variation in land management within a catchment can have a dominant influence on water partitioning. Consequently, in drought sensitive environments there is a need for careful assessment of the water use of different land use types, likely resilience to future climate change and implications for groundwater recharge and runoff.

We monitored isotopes in precipitation, soil water and groundwater over the growing season of 2021 (March – October) under 8 plots with contrasting land cover in the drought-sensitive Demnitzer Millcreek Catchment (DMC) in NE Germany. These encompassed traditional arable crops, cropping schemes with water conservation measures (e.g. syntropic crops and agroforestry), grasslands and contrasting forests. The isotope monitoring was complemented with a flux tower, forest sap flow monitoring, pasture lysimetry and soil moisture measurements to provide hydroclimatic and ecohydrological context.

The growing season of 2021 being relatively wet compared to the drought years of 2018-20. Nevertheless, ET was high and soil moisture declined from May onward with only a large (60mm) event in June substantially replenishing the soil water storage before more general re-wetting in autumn. Soil moisture availability was generally highest under grassland and syntropic crops and lowest under forests. In general, precipitation isotopic composition varied during the summer, and was largely tracked by soil water isotopes, though at all sites variations were increasingly damped and lagged with depth. Soil water isotopes generally plotted close to the local meteoric water line, with limited effects of soil evaporation showing differences in interception and transpiration mainly explained the differences in soil moisture between sites. Estimates of soil water ages showed that the upper soils of arable sites had the greatest variability in isotopic composition and most rapid turnover of water, whilst soil water under trees had more limited isotopic variability, was much older and showed low levels of groundwater recharge.

Our study illustrated the advantage of monitoring the spatial variability of natural stable water isotope abundance in soil-vegetation systems to understand heterogeneity in water partitioning. Further, conservation measures like syntropic agriculture were tentatively shown to be a useful adaptation against dryer climatic conditions as this site was able to retain the highest proportion of precipitation in the soil for crop growth. However, monitoring over multiple growing seasons with contrasting hydroclimatic conditions is needed for a fuller assessment.
Morphospace, composition and texture of Lake Salda microbialites
Authors: Gunes Yagmur , Baldes Matthew J. , Gong Jian , Bosak Tanja , Balci Nurgul
Published: March 2022

The discovery of hydrated magnesium carbonates in a paleolake in Jezero Crater, Mars, has inspired the study of carbonates associated with lacustrine systems on Earth. Lake Salda, Turkey, contains hydromagnesite-dominated microbialites in a mafic-rock hosted terrain. This alkaline lacustrine system provides an excellent natural laboratory in which to characterize various depositional environments and biosignature preserving potential of microbialites and other magnesium carbonate deposits. Here we aim to describe the textures, mineral composition, and macroscopic morphology of hydromagnesite structures in Lake Salda. All microbialites are covered by a thick, sticky organic-rich layer dominated by diatoms and cyanobacteria. A close association of contemporary hydromagnesite precipitation with organic-rich layers in microbialites indicates biologically mediated precipitation. Microbialites around the lake exhibit a range of morphologies, including finger-like, mini columnar, domical, and structureless. The recently exposed microbialites commonly contain colloform and cerebroid structures with fine, crude lamination, vuggy and globular textures. Layered microscopic textures preserve evidence of partially mineralized filamentous bacteria that trapped detrital grains and also contain globules embedded in extracellular polymeric substances, and dense hydromagnesite. The differences in mineralogy, density, and organic preservation potential within these textures likely correspond to the depositional environment. For example, the globular textures are closely associated with the purple layers in microbialites, including the layers in the recently sampled microbialites from the deeper part of the lake (ca. 10 m). These layers may form in the presence of anoxygenic purple sulfur bacteria. Our preliminary results suggest that the textures and macroscopic structures of hydromagnesite microbialites may record and reflect relationships among carbonate minerals, environmental factors, and microbial community composition.
Kaolinite deposition and clogging of moving streambeds under losing and gaining flow conditions
Authors: Shimony Tomer , Saavedra Cifuentes Edwin , Packman Aaron , Teitelbaum Yoni , Arnon Shai
Published: March 2022

Clay deposition in streambed sediment can cause partial or complete clogging of the streambed. It was shown that clogging reduces the hyporheic exchange flux (HEF) between the water column and the streambed and can negatively affect stream ecosystems. For example, by reducing the fluxes of nutrients to benthic microorganisms. It has been shown that flow from the stream towards the groundwater (losing) or in the opposite direction (gaining) also affects clay deposition patterns; however, this has only been investigated experimentally under stationary bedform conditions. Here, we investigated the dynamics of clogging during moving bedform conditions and under losing or gaining fluxes. We conducted a series of experiments in a 640 long and 29 cm wide flume packed with sand (D50 = 270 μm). The flume is equipped with a drainage system that can simulate losing or gaining conditions at prescribed flux. We conducted experiments under two different losing fluxes and two gaining fluxes (10 and 20 cm/day), while stream velocity was constant at 29 cm/day.  During the experiments, kaolinite was added as a discrete series of pulses. Each pulse was added after the kaolinite deposition stabilized (2 - 4 days). HEF and the vertical hydraulic conductivity were quantified before each kaolinite addition by salt tracer test, and the “falling-head” methods, respectively. Morphodynamic properties of the bed were measured using high-frequency acoustic doppler sensor and time-lapse photometry timeseries. The kaolinite deposition rate was measured with a turbidity sensor, while core samples were taken at the end of the experiment to analyze the vertical deposition patterns. Preliminary results showed that HEF and hydraulic conductivity in losing conditions decreased from their initial value by 95% and 37%, respectively, while in gaining conditions, HEF decreased by 72% and hydraulic conductivity by 23%. We also observed that under gaining conditions, most of the clay was deposited at the upper part of the sediment (in the moving fraction). In losing conditions, kaolinite was also found deeper in the bed and below the moving fraction of the streambed. In all cases, most of the kaolinite mass was deposited at a depth of less than five cm. The results show a significant effect of stream-groundwater interactions on HEF and on suspended particle deposition in situations where the bed is under movement. Therefore, the quantification and prediction of clay deposition patterns in streams with strong interactions with groundwater has to be included in models that predict clogging and transport processes in streams. 
Spatiotemporal distribution of hydrological extremes in Brazil
Authors: Gesualdo Gabriela , Benso Marcos , Brunner Manuela , Mendiondo Eduardo
Published: March 2022

To reduce the future negative impacts of hydrological extremes, it is crucial to understand the spatiotemporal variability of flood and drought hazard and social, economic, and environmental vulnerabilities. Such understanding is particularly important in developing countries which are strongly vulnerable to hydrological extremes because of greater economic dependence on climate-sensitive primary activities and infrastructure. Brazil is increasingly affected by hydrological extreme events and related losses. The sum of damages and losses caused by recurrent floods and droughts has a substantial impact, especially in small and medium-sized municipalities. Developing disaster resilience and adaptation strategies requires an understanding of the risks related to floods and droughts and how they are spatially distributed and related across the country. Therefore, we present a risk analysis of how floods and drought are distributed and spatially connected across Brazil. To assess flood hazard, we rely on frequency analysis and spatial dependence measures. Moreover, the vulnerabilities towards drought and flood hazard were derived using data from the Brazilian atlas of natural disaster: damages and losses($), people affected, deaths, and homelessness. Based on the results, we divide the country into regions suitable to risk pooling, i.e. groups of municipalities that can cooperatively share costs, liabilities and risks.These regions can implement adaptation measures at the regional level, i.e. flood-drought risk insurance framework, using conjugate return periods, extended losses, multi-risk coverage, and composite willingness to pay and adapt. Our risk analysis will support the development of adaptation plans to hydrological extremes at the catchment and regional scale.
Assessing recent anthropogenic disturbances and environmental recovery in the Nalón estuary (Asturias, N Spain)
Authors: Gardoqui Jon , Cearreta Alejandro , García-Artola Ane , Irabien María Jesús , Gómez-Arozamena José , Villasante-Marcos Víctor
Published: March 2022

The estuaries of the northern Atlantic Iberian margin are susceptible to alteration due to human activities and transformation from relative sea-level rise.

The Asturian region, northern Atlantic Iberian margin, is characterized by extensive coal and polymetallic mineral deposits, including mercury ores, which have been intensively exploited since the late 19th century. In particular, the Nalón estuary has been subjected to intense physico-chemical modifications as a result of mining of such deposits in the catchment area and port activities.

This research aims to decipher the environmental transformation of the Nalón estuary and the natural and/or anthropogenic forcing mechanisms during the last 200 years. We employed a multiproxy approach (i.e., benthic foraminifera, trace metals, grain size, magnetic susceptibility, microparticles and natural and artificial radionuclides) to study three 50-cm long sediment cores extracted from the middle and lower estuary. The records show degraded ecological conditions that persisted since ~1880. These were driven by the alteration of hydrological patterns, as a result of coal and mercury mining activities in the river basin and physical modifications (e.g., factory dams, dredging activities) performed in the lower estuary. Additionally, the study of eighteen surface samples, collected from different estuarine subenvironments along the main axis of the estuary, reveals the existence of a great number of living foraminifera associated with a remarkable environmental recovery since ~2010, coinciding with the end of mining and dredging activities.

Future multidisciplinary studies of these regional estuarine areas will be critical to establishing appropriate coastal management practices under a climate change and sea-level rise context.
Cloud coverage estimation via deep learning applied to all-sky data in Romania : First Results
Authors: Anghel Simon , Voiculescu Mirela , Nedelcu Dan-Alin , Birlan Mirel
Published: March 2022

Measuring the level of cloud coverage (CC) is important when analysing the absorption of solar radiation, the cloud formation process, and also to improve the forecast in general. This is becoming a more common task with the availability of digital sensors and their usage in monitoring the sky.

In this study we present a method of estimating the level of cloud coverage using Deep Learning (DL) applied to all-sky images of Meteorites Orbits Reconstruction by Optical Imaging (MOROI) network.

To label the data, a supervised validation was employed on the daytime images captured during the course of two years, recorded on Galati, Romania These were divided into three groups; CC <20%, CC between 20-80%, and CC >80%. Next, a set of DL models were trained, optimized and tested towards accurately classifying images according to each group.

We found that the classification accuracy can range between 89-95 % depending on how the cloud coverage is labeled and how the daytime is defined. This is mostly due to thin cirrus clouds, tricking the models, or poor sky illumination during sunrise or sunset. We discuss these methods and present a few strategies which circumvent classification problems, to further increase the accuracy of models.

The next step is to extend the study on the rest of the network, and also combining it with other sensors (e.g. satellite data) in order to understand the cloud-circulation coupling and its impact across climate models.
Contributions of Eric Wood to hydrologic remote sensing
Authors: Pauwels Valentijn
Published: March 2022

Remote sensing is one of the major sources of data for the hydrological sciences. This presentation provides an overview of the contributions of Eric Wood to this field, encompassing studies from the last three decades, across multiple continents and different spatial and temporal scales. The remotely sensed variables include, but are not limited to, surface soil moisture content (through active and passive remote sensing), precipitation, and evapotranspiration. A general overview of the field and satellite campaigns in which these methods and products were developed will be presented. A short overview of the application of these products for different purposes is also provided.
Modelling Subglacial Hydrology under Future Climate Scenarios in Wilkes Subglacial Basin, Antarctica
Authors: Siu Kevin , Dow Christine , Morlighem Mathieu , McCormack Felicity , Hill Tim
Published: March 2022

The Greenland and Antarctic ice sheets have differing climates, which makes surface melt a significant hydrological source in Greenland but not currently in Antarctica. Due to changing climate and warming air temperatures, Antarctica is predicted to experience more surface meltwater in the future. This will likely lead to surface features common in Greenland today, such as supraglacial lakes and moulins, to also form over grounded ice in Antarctica. Moulins in particular are important because they will route this surface melt into basal drainage networks. The resulting change in subglacial drainage characteristics and water volumes will potentially have far-reaching impacts on ice dynamics, ice shelf melt, grounding line stability, and ultimately global sea level rise. To examine this, we model the hydrological system in Wilkes Subglacial Basin, East Antarctica with the future climate in mind by incorporating moulins and surface melt to try to understand the impact that this will have on ice sheet and ice shelf dynamics. We use predictive data generated by the Community Climate System Model 4 (CCSM4) for surface runoff in Antarctica for the year 2100 as inputs to the Glacier Drainage System (GlaDS) subglacial hydrology model. We compare the modelling results from two different Representative Concentration Pathway (RCP) scenarios, RCP 2.6 and RCP 8.5. Moulin locations are predicted using current strain rates along preferential surface hydrology flow pathways and we also compare modelling results with different numbers and locations of moulins. Preliminary results show that even under the lower RCP 2.6 scenario, surface water input significantly alters basal drainage rates, channel extent, and water pressure near the grounding line. The changes are focussed during the modelled summer melt season with the hydrological system settling towards its current state over winter. This demonstrates that the future state of the climate will have an impact on the subglacial hydrology of Antarctica and, in turn, on ice flow speeds and ice shelf melt rates near the grounding line.
Geochemical evolution and reaction mechanisms controlling groundwater chemistry in the Pra Basin (Ghana)
Authors: Manu Evans , De Lucia Marco , Schleicher Anja Maria , Kempka Thomas , Kühn Michael
Published: March 2022

As the demand for water supply increases with population growth, the quality of ground and surface water resources is deteriorating rapidly in many regions worldwide, particularly in Ghana. This situation has put supply systems under severe pressure as many of the available water resources are polluted by anthropogenic activities such as mining, agriculture, domestic and industrial sewage. Ghana's water quality problems are not different from current global challenges, as many surface waters and some aquifers have been polluted by mining activities and to some extent also by agriculture and industrial seepage. The Pra Basin is one of the most affected basins in Ghana with a total area of around 2,300 km2 and a population of over five million people. The economic history of the basin is unparalleled as it is home to the country's major mineral deposits, including gold, bauxite, manganese, and diamonds. Recent studies have shown significant amounts of water pollutants including mercury (Hg), arsenic (As), lead (Pb), iron (Fe), manganese (Mn), cadmium (Cd), selenium (Se) and nitrate (NO3). The underlying geology of the Pra Basin consists mainly of metasediments and granitoids. The occurrence of groundwater is controlled by the development of secondary porosities through fractures, joints, and faults. This study provides insights into the evolution and hydrogeochemical processes that control the groundwater quality in the Pra Basin. The methodology applied here includes field sample collection, statistical analysis of hydrochemical data, petrographic and mineralogical analysis of rock outcrops and geochemical modelling. Groundwater samples were taken from shallow (mainly hand-dug wells with depths <10 m) and deep aquifers (mainly boreholes with depths >30 m) throughout the basin. Samples were analysed for major ions, and trace metals using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Ion Chromatography (IC), and a Picarro L-2140i Ringdown Spectrometer. Multivariate statistical analyses, inverse and forward geochemical modelling were applied to the hydrochemical data of around 100 water samples. The mineral phases used as model input were obtained from X-ray Diffraction (XRD) measurements of rock outcrops from the study area and mainly include chlorite, albite, muscovite, biotite, and calcite. The analysis of the results shows that the geochemistry of the groundwater resources in the Pra Basin is mainly controlled by water-rock-interaction. Within the given uncertainty limits, the dissolution of carbonates and weathering of silicates are the drivers for the chemical development of the groundwater in the basin. The presented findings will support the development of sustainable water resources management strategies and contribute to mitigating future contamination.
Evaluating scant surface evidence of deep lithosphere removal: Towards a more comprehensive record
Authors: He John , Kapp Paul
Published: March 2022

Lithosphere removal beneath orogenic plateaus are transient events that must often be inferred from the absence of evidence: for example, unexplained topographic uplift in the geologic record, or the absence of high-velocity mantle lithosphere. Even when foundering events do leave traces of their occurrence on the surface, the low preservation potential of such evidence leaves incomplete and ambiguous records. Distinctive features include isotopically juvenile magmatism and transient surface subsidence that form localized, internally drained hinterland basins and playas. However, basaltic volcanism and related lacustrine sediments are rarely well preserved, and this limits our ability to evaluate the role of lithosphere removal in orogenesis to only select localities. To develop a more comprehensive record of this process, and facilitate comparisons between regions with copious surface and/or geophysical evidence of lithospheric foundering with regions where the evidence is scant, whether poorly preserved or not yet recognized, we present the detrital record from young strata in internally-drained hinterland basins as a proxy for foundering-related magmatism. The detrital samples include unconsolidated to poorly consolidated lacustrine sediment of the Bidahochi paleolake from the Colorado Plateau, which is associated with the isotopically juvenile (positive epsilon Nd) Hopi Buttes Volcanic field; Oligocene siltstone from the Pamir Plateau with juvenile isotopic signature (positive epsilon Hf); and Eocene-Oligocene sandstone from several localities on the Tibetan Plateau. Integration of isotope geochemistry, trace element geochemistry, and thermochronology of detrital zircon and apatite presents a promising approach to reconstruct a continuous record of low-volume magmatism, both eroded and preserved. Ti-in-zircon thermometry, Ce-U-Ti oxybarometry, and REE proxies for depth of magmatic differentiation potentially provide a means of distinguishing zircon crystals associated with hinterland magmatism from that associated with arc magmatism. Using these datasets, we consider whether lithospheric foundering can be associated with recognizable patterns that are similar across orogens, and whether geochemical shifts in hinterland magmatism reveal first-order differences in the temporal scale of lithosphere removal in different orogens. 
Identification of combined influence of climatic variables on indian summer monsoon rainfall extremes
Authors: Krishnankutty Nair Athira , Singh Sarmistha
Published: March 2022

Spatio-temporal variability of Indian Summer Monsoon Rainfall (ISMR) is responsible for extreme events like floods and droughts across India. In recent decades, the incidence of extreme precipitation events during ISMR is increased significantly, which are primarily linked to climatic variables like El Niño Southern Oscillation (ENSO), Equatorial Indian Ocean Oscillation (EQUINOO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). In this study, extreme precipitation indices (EPIs) like consecutive dry days (CDD), consecutive wet days (CWD), maximum consecutive 5-day precipitation (Rx5day), and 95th percentile (R95p) have been considered to explain the characteristics of ISMR extremes. Moreover, a regional analysis has been carried out using the multiple wavelet coherence method to determine the coupled association of climatic oscillations with EPIs. Here, two-, three-, and four- climatic variable combinations have been applied to identify the best combination which explains the fluctuations of ISMR extremes all over India. Results indicate that two or more climatic oscillations could be sufficient particularly, AMO-ENSO-EQUINOO and AMO-ENSO-PDO are the best combinations to explain the variability of ISMR extremes across India. Apart from this analysis, wavelet decomposition and reconstruction analysis have also been performed to understand the scale-specific variability of the spatial-extreme precipitation. More than half of India had a significant correlation between reconstructed modes of ISMR extremes and climatic oscillations at interdecadal and multidecadal scales (8-16 and 16-32 -years), despite their interannual periodicities. This indicates that the non-stationary behaviour of the ISMR extremes was strongly associated with climatic variables at higher scales. 
Eruption forecasting at Strokkur geyser, Iceland: An application of Permutation Entropy
Authors: Sudibyo Maria , Eibl Eva P.S. , Hainzl Sebastian
Published: March 2022

A volcanic eruption is usually preceded by increased seismic activity resulting from magma propagation. Although these precursors can be detected by a modern seismometer, it is still a challenge to answer whether they will be followed by an actual eruption and when the eruption will occur after precursors are detected. The time between the start of volcanic unrest and the actual eruption is crucial. Therefore, there is a need for an assessment tool that is applicable in real-time. Permutation Entropy (PE) has been recently suggested to be a promising tool for the prediction of volcanic eruptions. It is a robust yet simple tool to quantify the complexity of time series. We aim to find out whether there is a distinct feature in the temporal variation of PE that is useful for eruption forecasting. We performed several synthetic tests to understand how PE works and how to choose the optimum input parameters for a signal with certain properties. We then applied this knowledge to calculate PE of seismic data that recorded eruptions of Strokkur geyser, Iceland on the 10th of June 2018. 78 eruptions occurred within five hours of observation. We used this fast-repeating process to check if the eruptions cause a repetitive pattern of PE. The input parameters used for PE calculation are a window length of 1 second, an embedding dimension of 5, and a delay time of 0.067 seconds. Our results show a distinct, repeating pattern of the PE that is consistent with the phases in the eruptive cycle of Strokkur as described by Eibl et al. (2021). The PE drops in the stage of bubble accumulation at depth, then undergoes repeated increasing and decreasing patterns during regular bubble collapses at depth in the conduit, and finally continuously increases as a precursor towards the time of eruption on the surface. The average duration of this precursor to the eruption is about 10 seconds.