bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen isotopes in phlogopite indicate crustal fluids in the UG2 chromitite layer, Bushveld Complex
Authors: Zhou Haoyang , Trumbull Robert , Veksler Ilya , Glodny Johannes , Bindeman Ilya
Published: March 2020

The Upper Group 2 (UG2) chromitite layer in the upper Critical Zone of the Bushveld Complex, South Africa, is the world’s largest PGE orebody. The UG2 is typically 0.5 to 1.5 m thick and it consists of 75–90 modal % chromite with interstitial silicate and sulfide minerals. Although a minor component, phlogopite is important because it is a hydrous phase. It has been noted that the UG2 chromitite contains more abundant phlogopite (locally > 1 modal %) than the surrounding pyroxenite layers (Mathez and Mey, 2005). More and more studies suggest that water plays an important role in the UG2 chromite formation and in PGE enrichment or remobilization (e.g., Li et al., 2004; Mathez and Mey, 2005; Schannor et al., 2018). The source of the water is controversial, and this motivated our ongoing study of hydrous minerals in the UG2.

We determined the chemical composition and hydrogen isotope ratio of phlogopite from the chromitite layer and from the surrounding pyroxenite in drill cores from two sites the eastern and western Bushveld (Nkwe and Khuseleka, respectively). The δD values of phlogopite in chromitite from the eastern site are -38.2 to -25.5‰ (mean = -29.7‰, n = 6). The corresponding values from the western site are similar, with -34.6 to -31.6‰ (mean = -33.2‰, n = 6). The δD values of phlogopite from pyroxenite are more variable, ranging from -43.1 to -26.1‰ for the eastern site (mean = -32.9‰, n = 4) and from -38.7 to -26.1‰ for the western site (mean = -31.7‰, n = 3).

Published whole-rock δD values for silicate cumulate rocks in the upper Critical Zone are -93 to -55‰ (Mathez et al., 1994), which are similar to mantle values (-70±10%; Boettcher and O'neil, 1980) and are interpreted as magmatic.  In comparison, our δD values of phlogopite from UG2 are much higher and suggest a significant contribution of crustal fluids. Harris and Chaumba (2001) estimated a δD value of -22‰ for paleo-meteoric water in the Bushveld Complex. Given the relative homogeneity of the phlogopite δD data in both sites of the complex, and the primary appearance of the grains in thin section, we argue that the crustal fluids were incorporated in the magma before the crystallization of the UG2 layer. Triple oxygen isotopes will test our hypothesis further.

 

References: Boettcher & O'neil (1980) Amer. Jour. Sci. 280A, 594–621. Harris & Chaumba (2001) J. Petrol. 42, 1321–1347. Li et al. (2004) Econ. Geol. 99, 173–184. Mathez et al. (1994) Econ. Geol. 89, 791–802. Mathez & Mey (2005) Econ. Geol. 100, 1616–1630. Schannor et al. (2018) Chem. Geol. 485, 100–112.
Reconstructing the Early Eocene Sediment Routing System of the south-eastern Pyrenees
Authors: Garcés Miguel , López-Blanco Miguel , Beamud Elisabet , Muñoz Josep Anton , Arbués Pau , Valero Luis , Vinyoles Andreu
Published: March 2020

The Early Eocene was the period of most intense plate collision during the building of the Pyrenean orogen. Tectonic loading of the overriding European plate caused flexure of the subducting Iberian plate and formation of an elongated foredeep connected westward with the Atlantic Ocean. The uneven distribution of the Triassic evaporites caused the formation of a thrust salient in the central Pyrenees related to tectonic inversion of the pre-existing Mesozoic rift basins. This process ultimately resulted in the partitioning of the foreland basin and the isolation of the Ripoll Basin in the East from the Tremp-Graus and Ainsa-Jaca basins in central and western south-Pyrenees. The precise timing and the surface processes related to this reorganization of the sediment routing system remains not fully understood. Early tectono-stratigraphic reconstructions envisaged a scenario of isolation of the eastern Pyrenean Foreland basin in the early Eocene, while other recent studies on detrital zircon geochronometry suggest that the sedimentary transfer system in the Tremp-Graus basin connected upstream to the Ripoll basin until middle Lutetian times. In this contribution we discuss constraints on the early Eocene paleogeography of the south-eastern Pyrenees in the light of a revised chronostratigraphic scheme. We put forward a scenario that tries reconciling all available structural, stratigraphic, petrologic, geochronologic, and sedimentologic datasets.
An inter and transdisciplinary participatory approach to assess the current flood risk management practices in Ghana
Authors: Almoradie Adrian , Madruga de Brito Mariana , Evers Mariele
Published: March 2020

The understanding of the multifaceted nature of flood risk management (FRM) of a country requires the consideration of both social, technical as well as governance aspects. The inclusion of these components in the analysis and assessment of FRM allows comprehending the veracity of its interdependencies, its strengths and weakness that would, in turn, aid in improving the current system.

This paper presents an inter and transdisciplinary and participatory multi-method participatory approach to promptly assess Ghana’s current FRM practices, describing the current gaps and opportunities for improving FRM. Here, we describe the challenges on its institutional, governance and implementation, scientific, technical and social capacity levels and potential ways forward. The methodological  approach comprised a systematic literature review of 53 peer-reviewed articles, stakeholder analysis, engagement of stakeholders on workshops through focus group discussion and collaborative mapping, interviews with key individual stakeholders, and household surveys with 1,479 citizens living in flood prone areas. The stakeholders were identified and categorized into governance and implementation, academia and research and security agencies.

Results show that stakeholders have diverse and even contradictory views regarding FRM in Ghana. Overall, the findings indicate that: (1) the most critical regions are Accra, Kumasi, and the White Volta river basin, (2) the most crucial aspects for reducing vulnerability and exposure are related with high population density, social hotspots and location of Critical Infrastructure, (3) FRM  are unsustainable and unintegrated and it heavily relies on short-term projects and external funders, (4) reliable data is scarcily available and communities need to be engage more in the planning and provision of information and data, (5) there are weaknesses in flood early warning systems (FEWS), institutional collaborations, human capacity, trained FRM professionals and problems in policy implementation, (6) the most important vulnerability criteria are the existence of FEWS, disaster relief agencies, areas with a high density of children and poverty rate, (7) the interviewed communities in Accra and Kumasi claimed that flood disasters are caused mainly by human activities and interventions.

The applied participatory multi-method approach proved to be useful to capture the factual situation of the FRM in Ghana, this was shown when cross-referencing the results of the different methods. The use of a participatory and inter and transdisciplinary approach allowed capturing a multitude of views as well as the stakeholders needs and requirements in terms of FRM. The co-production of knowledged allowed improving the credibility, salience and legitimacy of project outputs.
Detailed Investigation of Seismic Anisotropy in the Upper Mantle of the Northern Aegean Region
Authors: Erman Ceyhun , Yolsal-Çevikbilen Seda , Eken Tuna , Taymaz Tuncay
Published: March 2020

Seismic anisotropy studies can provide important constraints on geodynamic processes and deformation styles in the upper mantle of tectonically active regions. Seismic anisotropy parameters (e.g. delay time and fast polarization direction) can give hints at the past and recent deformations and can be most conventionally obtained through core-mantle refracted SKS phase splitting measurements. In order to explore the complexity of anisotropic structures in the upper mantle of a large part of the Aegean region, in this study, we estimate splitting parameters beneath 25 broad-band seismic stations located at NW Anatolia, North Aegean Sea and Greece mainland. To achieve this we employ both transverse energy minimization and eigenvalue methods. Waveform data of selected earthquakes (with Mw ≥ 5.5; 2008-2018 and with epicentral distances between 85°–120°) were retrieved from Earthquake Data Center System of Turkey (AFAD; http://tdvm.afad.gov.tr/) and European Integrated Data Archive (EIDA; http://orfeus-eu.org/webdc3/). A quite large data set, the majority of which have not been studied before, were evaluated in order to estimate reliable non-null and null results. In general, station-averaged splitting parameters mainly exhibit the NE-SW directed fast polarization directions throughout the study area. These directions can be explained by the lattice-preferred orientation of olivine minerals in the upper mantle induced by the mantle flow related to the roll-back process of the Hellenic slab. We further observe that station-averaged splitting time delays are prone to decrease from north to south of the Aegean region probably changing geometry of mantle wedge with a strong effect on  the nature of mantle flow along this direction. The uniform distribution of splitting parameters as a function of back-azimuths of earthquakes refers to a single-layer horizontal anisotropy for the most part of the study area. However, back azimuthal variations of splitting parameters beneath most of northerly located seismic stations (e.g., GELI, SMTH etc.) imply the presence of a double-layer anisotropy. To evaluate this, we performed various synthetic tests especially beneath the northern part of study region. Yet, it still remains controversial issue due to the large azimuthal gap and thus requires further modelling which may involve the use of joint data sets.
Assessment of Predictive Uncertainty of Data-Driven Environmental Models
Authors: Knüsel Benedikt , Baumberger Christoph , Zumwald Marius , Bresch David N. , Knutti Reto
Published: March 2020

Due to ever larger volumes of environmental data, environmental scientists can increasingly use machine learning to construct data-driven models of phenomena. Data-driven environmental models can provide useful information to society, but this requires that their uncertainties be understood. However, new conceptual tools are needed for this because existing approaches to assess the uncertainty of environmental models do so in terms of specific locations, such as model structure and parameter values. These locations are not informative for an assessment of the predictive uncertainty of data-driven models. Rather than the model structure or model parameters, we argue that it is the behavior of a data-driven model that should be subject to an assessment of uncertainty.

In this paper, we present a novel framework that can be used to assess the uncertainty of data-driven environmental models. The framework uses argument analysis and focuses on epistemic uncertainty, i.e., uncertainty that is related to a lack of knowledge. It proceeds in three steps. The first step consists in reconstructing the justification of the assumption that the model used is fit for the predictive task at hand. Arguments for this justification may, for example, refer to sensitivity analyses and model performance on a validation dataset. In a second step, this justification is evaluated to identify how conclusively the fitness-for-purpose assumption is justified. In a third step, the epistemic uncertainty is assessed based on the evaluation of the arguments. Epistemic uncertainty emerges due to insufficient justification of the fitness-for-purpose assumption, i.e., if the model is less-than-maximally fit-for-purpose. This lack of justification translates to predictive uncertainty, or first-order uncertainty. Uncertainty also emerges if it is unclear how well the fitness-for-purpose assumption is justified. We refer to this uncertainty as “second-order uncertainty”. In other words, second-order uncertainty is uncertainty that researchers face when assessing first-order uncertainty.

We illustrate how the framework is applied by discussing to a case study from environmental science in which data-driven models are used to make long-term projections of soil selenium concentrations. We highlight that in many applications, the lack of system understanding and the lack of transparency of machine learning can introduce a substantial level of second-order uncertainty. We close by sketching how the framework can inform uncertainty quantification.
Trees as sensors of metallic pollution dissemination during past flood events
Authors: Delapierre Annick , Ballesteros Canovas Juan Antonio , Buzzi Jorge , Stoffel Markus , Slaveykova Vera I
Published: March 2020

Anthropogenic activities such as mining are responsible for acid drainage and metal-enriched waters that in turn contaminate river ecosystem downstream due to the weathering of exposed minerals or tailing dam failures. The release of heavy metals is especially disturbing because of their high toxicity and long permanence. Detecting highly polluted areas and their links with high (low) water flow stages can contribute to a better land management of affected areas. Here, we test if trees growing in different geomorphic positions along a river record heavy metal uptake during past floods. To this end, we applied dendrochemical analysis to twenty-five Pinus pinaster Ait. growing on the banks of Odiel River flowing into the Atlantic Ocean located at in south-western Spain. In addition, five trees disconnected from the river channel were sampled as references values. For each tree, we extracted 1 cm-sized increment cores. After dating dendrochronologically, we isolated tree-ring sequences into 5-year blocks matching with the dates of major floods in the catchments. Samples were then analyzed using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Our results suggest coherence between tree locations and the amount of heavy metal accumulated in the tree over the last decades. Thus, we clearly show a control of river morphological units on the  heavy metal concentrations in trees, being higher in those trees located on meander cut banks than in trees on point-bar sedimentary structures. We conclude that trees could be a natural proxy to trace chemical dispersion and pollution related to flood events in highly anthropogenic catchments.
Multi-thousand member ensemble atmospheric simulations with global 60km resolution using climateprediction.net
Authors: Watson Peter , Sparrow Sarah , Ingram William , Wilson Simon , Marie Drouard , Zappa Giuseppe , Jones Richard , Mitchell Daniel , Woollings Tim , Allen Myles
Published: March 2020

Multi-thousand member climate model simulations are highly valuable for showing how extreme weather events will change as the climate changes, using a physically-based approach. However, until now, studies using such an approach have been limited to using models with a resolution much coarser than the most modern systems. We have developed a global atmospheric model with 5/6°x5/9° resolution (~60km in middle latitudes) that can be run in the climateprediction.net distributed computing system to produce such large datasets. This resolution is finer than that of many current global climate models and sufficient for good simulation of extratropical synoptic features such as storms. It will also allow many extratropical extreme weather events to be simulated without requiring regional downscaling. We will show that this model's simulation of extratropical weather is competitive with that in other current models. We will also present results from the first multi-thousand member ensembles produced at this resolution, showing the impact of 1.5°C and 2°C global warming on extreme winter rainfall and extratropical cyclones in Europe.
Soil texture mediated microbial activity affects the transfer of litter-derived carbon to soil organic matter
Authors: Angst Gerrit , Pokorný Jan , Meador Travis , Hajek Tomáš , Frouz Jan , Prater Isabel , Mueller Carsten W , van Buiten Gerard , Angst Šárka
Published: March 2020

Knowledge about the nexus between litter decomposition and soil organic matter formation is still scarce, likely because litter decomposition studies are often conducted in the absence of mineral soil. Even if mineral soil is considered, variations in soil texture, which should substantially influence decomposition and soil C sequestration via, e.g., different capacities to store C or host microbial communities, have been neglected. Here, we examined the effect of soil texture on litter decomposition and soil organic matter formation by incubating sand- and clay-rich soils. These soils, taken under C3 vegetation, were amended with C4 litter to trace the fate of organic matter newly entering the soil. While we found only small amounts of litter-derived carbon (C) in the mineral soils after our six-month experiment, the microbial activity and amount of remaining litter between the sand- and clay-rich soils substantially differed. A high microbial activity combined with higher amounts of litter-derived C and a higher remaining litter mass in the clay-rich soil indicate a more effective transformation of litter to soil organic matter as compared to the sand-rich soil. In the sand-rich soil, microbial activity was lower, less soil C was litter-derived, and the litter lost more of its mass. We explain the apparently contradictory results of higher microbial activity and concurrently higher C contents with a more effective microbial pathway of SOM formation in the clay-rich soil. Our results indicate that soil texture does not only play a role in the provision of reactive surfaces for the stabilization of C but will also affect the decomposition of litter via effects on microbial activity, ultimately determining if litter C is transferred to the soil or respired to the atmosphere.
Coral reconstructed Mid-Holocene seasonality in the southwestern Caribbean
Authors: Skiba Vanessa , Struck Ulrich , Reuning Lars , Garbe-Schönberg Dieter , Frank Norbert , Leinfelder Reinhold , O'Dea Aaron , Zinke Jens
Published: March 2020

Seasonality is a dominant factor in the Earth’s climate system, but proxy reconstructions on this time scale are sparse. Corals provide an excellent archive to reconstruct environmental conditions on seasonal time scale using geochemical proxies. Here, we use subfossil (~6.2-7.1 ka BP) Siderastrea siderea and Pseudodiploria labyrinthiformis corals from a pristine Mid-Holocene reef, located in Panamá, southwestern Caribbean. Mid-Holocene insolation seasonality in the Northern Hemisphere was stronger than at present. We investigate the resulting changes in SST and hydrological seasonality using coral Sr/Ca, δ18O and δ13C. To evaluate, if the coral heads can be utilised for geochemical analyses, they have been screened for diagenetic alteration (2D-XRD, thin section analysis). Obtained modern coral Sr/Ca-SST based annual cycle corresponds well with in situ measured SST. Fossil coral Sr/Ca-SST based cycles exceed the modern one by up to 50%. Fossil coral δ18O seasonal amplitudes are higher than the modern one by up to 30% and show a reduction in the mean gradient between wet and dry period, attributable to the northward shift of the Intertropical Convergence Zone. Increased SST and δ18O seasonality are consistent with model simulated SSTs (Kiel Climate Model) and model-based calculated pseudocoral δ18O, but the model underestimates the seasonality increase in the Mid-Holocene.
Decadal variability of circulation and oxygen in the equatorial Atlantic
Authors: Brandt Peter , Hahn Johannes , Sunke Schmidtko , Tuchen Franz Philip , Kopte Robert , Kiko Rainer , Bourlès Bernard , Dengler Marcus
Published: March 2020

The upper ocean circulation of the tropical Atlantic experiences long-term changes associated with different climate modes, but is at the same time expected to adjust to changes in the meridional overturning forced by climate warming. While observations of decadal variability of the surface circulation are generally based on satellite altimetry, direct observations of subsurface circulation mostly rely on very few long-term mooring sites typically covering energetic currents such as the Atlantic Equatorial Undercurrent (EUC). Here we focus on the period 2006 to 2018 that was covered by an intense field program including oxygen and circulation observations in the equatorial and tropical North Atlantic. During the observational period, a strengthening of the EUC of about 20% was detected based on data of an equatorial current meter mooring at 23°W. The EUC strengthening is related to a similar strengthening of the subtropical cells (STC). These STC changes were forced by a trade wind intensification in both hemispheres, however, more pronounced in the north and in the western basin. The STC strengthening is found to be consistent with the observed 12-year oxygen increase in the equatorial band (i.e. south of about 5°N) in the upper 400m obtained from repeat ship sections along 23°W. Such strongly enhanced oxygen levels relative to climatological mean were also observed in the upper 300-400m during a recent cruise along the whole Atlantic equator from Africa to South America. Our results are discussed with regard to the superposition of internal climate variability likely associated to a recent phase shift in the Atlantic multidecadal variability and changes due to global warming including ocean deoxygenation and enhanced thermocline stratification.
MOPGA/Make Air Quality Great Again: Filling in the air quality data gap in Africa using lower-cost RAMP monitors
Authors: Subramanian Ramachandran , Beekmann Matthias , Malings Carl , Feron Anais , Formenti Paola , Giordano Michael , Marticorena Beatrice , Galy-Lacaux Corinne , Liousse Catherine , Adesina Joseph , Piketh Stuart , Amegah Kofi , Bahino Julien , Yoboué Véronique , Dungall Laouali , Garland Rebecca M , Gasore Jimmy , Madadi Vincent , Rajot Jean-Louis
Published: March 2020

Ambient air pollution is a leading cause of premature mortality across the world, with an estimated 258,000 deaths in Africa (UNICEF/GBD 2017). These estimated impacts have large uncertainties as many major cities in Africa do not have any ground-based air quality monitoring. The lack of data is due in part to the high cost of traditional monitoring equipment and the lack of trained personnel. As part of the “Make Air Quality Great Again” project under the “Make Our Planet Great Again” framework (MOPGA), we propose filling this data gap with low-cost sensors carefully calibrated against reference monitors.

Fifteen real-time affordable multi-pollutant (RAMP) monitors have been deployed in Abidjan, Côte d'Ivoire; Accra, Ghana; Kigali, Rwanda; Nairobi, Kenya; Niamey, Niger; and Zamdela, South Africa (near Johannesburg). The RAMPs use Plantower optical nephelometers to measure fine particulate matter mass (PM2.5) and four Alphasense electrochemical sensors to detect pollutant gases including nitrogen dioxide (NO2) and ozone (O3).

Using a calibration developed in Créteil, France, the deployments thus far reveal morning and evening spikes in combustion-related air pollution. The median hourly NO2 in Accra and Nairobi for September-October 2019 was about 11 ppb; a similar value was observed across November-December 2019 in Zamdela. However, a previous long-term deployment of the RAMPs in Rwanda showed that, for robust data quality, low-cost sensors must be collocated with traditional reference monitors to develop localized calibration models. Hence, we acquired regulatory-grade PM2.5, NO2, and O3 monitors for Abidjan and Accra. We also collocated RAMPs with existing reference monitors in Zamdela, Kigali, Abidjan, and Lamto (a rural site in Côte d'Ivoire). In this talk, we will present results on spatio-temporal variability of collocation-based sensor calibrations across these different cities, source identification, and challenges and plans for future expansion.
The impact of thermokarst lakes on streamflow generation in Central Yakutia (Russia): data assessment and modelling
Authors: Makarieva Olga , Nesterova Nataliia , Fedorov Alexander , Shikhov Andrey
Published: March 2020

Central Yakutian Plain (Russia) is situated in Eastern Siberia in the Lena River basin and is characterized by severe continental climate, continuous permafrost and flat relief. The combination of semi-arid climate, gentle topography and ice-rich permafrost provides favorable conditions for the development of thermokarst lakes. Poorly developed river drainage system and the distribution of thermokarst lakes within the river basins form the areas with internal drainage which contribute runoff to river network only in wet conditions. The results of such environment are the special hydrological regime of the region which is characterized by extreme seasonal and annual variability of streamflow.

In this project we study the hydrological processes in four rivers of Central Yakutia with the basin area from 1270 to 8290 km2 and available long-term streamflow data. Thermokarst lakes take up to 5-10 % of the area of those basins. Annual precipitation of this area is about 240 mm, while average annual streamflow varies from 1 to 15 mm depending on the river basin. Due to climate warming the number and area of thermokarst lakes in Central Yakutia is increasing (Kravsova, Tarasenko, 2011). The aim of the project is to investigate the impact of thermokarst lakes on hydrological regime and provide some reasonable projections of its changes in the future. Previous study (Lebedeva, 2018) has shown that the results of streamflow simulations in this region based on standard hydrological modeling approach were not satisfactory.

We used remote sensing data (Landsat images) to assess the seasonal and annual variation of thermokarst lakes area and their contributing area and combined that data with hydrological modelling of runoff formation processes. The hydrological model Hydrograph (Vinogradov et al., 2011) was applied in this study. The model contains the algorithms of heat and moisture dynamics in the upper part of soil profile which allow its use in the permafrost conditions. New part of the model algorithm was developed which considers the variations of thermokarst area depending on meteorological conditions, evaporation from open water areas and the dynamic of surface runoff retention depth. These model improvements allowed for the satisfactory results in streamflow simulations for historical period and future projections. In general, with the future development of thermokarst lakes in Central Yakutia one may expect the decrease of annual streamflow and its higher variation from one year to another.

Th results of the study will be presented. The study was funded by RFBR, project number 19-35-50030.
Diversity and strength of ice-related dimethyl sulfide sources in the Arctic
Authors: Levasseur Maurice , Lizotte Martine , Galindo Virginie , Gourdal Margaux , Gosselin Michel
Published: March 2020

Biogenic sources of sulfur are important precursors of aerosols in the Arctic during the summer months. Recent studies show that peaks in ultrafine particle formation events often coincide with hotspots of dimethyl sulfide (DMS) emissions from the marginal ice zone. During the last 10 years, we explored the diversity of DMS sources associated with the ice and at the marginal ice zone in the Canadian Arctic, and assessed how the projected changes in sea ice extent, thickness, and other properties could strengthen or weaken these emissions. Results from four Arctic expeditions presenting DMS concentrations and dynamics in snow, sea ice, melt ponds, under-ice water, and at the ice edge will be shown and discussed in the context of ongoing and future changes in the cryosphere. The analysis of the pooled dataset points toward an increase in DMS emissions in a warmer Arctic with a potential cooling feedback on climate.
Global assessment of 15 satellite- and model-based soil moisture products for operational drought monitoring
Authors: Sheffield Justin , Beck Hylke , Pan Ming , Miralles Diego , Reichle Rolf , Dorigo Wouter , Wagner Wolfgang , Wood Eric
Published: March 2020

Accurate and timely information about soil moisture is critical for drought monitoring, irrigation scheduling, and prediction of agricultural yields. We comprehensively assessed the temporal dynamics of 15 state-of-the-art (sub-)daily global surface soil moisture products, including five based on satellite retrievals, five based on "open-loop'' models (i.e., without data assimilation), and five based on models that assimilate satellite observations. As reference, we used in-situ soil moisture measurements at approximately 5-cm depth from 949 probes globally. Among the three single-sensor satellite products (AMSR2, SMAPL3, and SMOS), the L-band-based SMAPL3 performed best overall by a significant margin. Among the two multi-sensor satellite products (ESACCI and TC), TC achieved superior performance and outperformed SMAPL3 as well. The performance ranking of the five open-loop models (GLDAS, HBV-ERA5, HBV-IMERG, HBV-MSWEP, and VIC-PGF) is consistent with previous precipitation dataset evaluations, with HBV forced with MSWEP precipitation achieving the best performance not just among the open-loop models, but among all 15~products. Overall, the open-loop models performed better than the satellit products, reflecting the precipitation data quality in the conterminous US where most soil moisture probes are situated. The five models that assimilate satellite observations (GLEAM, HBV-ERA5+SMAPL3, HBV-IMERG+SMAPL3, HBV-MSWEP+SMAPL3, and SMAPL4) generally outperformed the open-loop models and exhibited a smaller spread in performance. Data assimilation yielded significantly improved performance when using less accurate precipitation (IMERG), but slightly degraded performance when using more accurate precipitation (MSWEP), demonstrating the value of data assimilation in poorly gauged regions.
Comparing the impacts of climate modes of variability on coastal aquifers of Portugal and California
Authors: Malmgren Katherine , Neves Maria da Conceição , Gorge Tina
Published: March 2020

Understanding the impact of climate variability on aquifer systems is important to improve future projections of groundwater availability, particularly in the context of increasing water scarcity. Coastal aquifers in Mediterranean regions are particularly sensitive to inter-annual and seasonal water storage fluctuations linked to climate forcing and climate-induced pumping. This comparative study examines the implications of climate variability modes on groundwater levels in coastal aquifers of California and Portugal. Piezometric levels in selected aquifers in Portugal (Leirosa-Monte Real and Campina de Faro) and California (Coastal Basins aquifers), spanning a period from 1988 to 2018, are analyzed using wavelet transform methods and principal component analysis. The methods expose not only the impact of the individual climate modes (AMO, PDO, ENSO, PNA in California and NAO, EA and SCAND in Portugal) but also the existence of complex transitive couplings among modes. Together, the climate modes are responsible for most (80%) of the inter-annual variability in groundwater storage in both Portugal and California coastal aquifers. However, our most important result is the recognition that transitive couplings greatly affect the hydrological responses both in Portugal and California. Coupled phases are linked to extreme piezometric levels and are associated with shifts in mode-interaction patterns. The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL.
Investigating the variability of renewable sources for energy management
Authors: Vatsikouridis Ioannis , Karkanis Konstantinos , Iliopoulou Theano , Dimitriadis Panayiotis , Koutsoyiannis Demetris , Mamassis Nikolaos
Published: March 2020

The integration of renewable energy sources in modern society has been given priority as these sources are regarded environmentally friendly. However, the variability of natural energy sources, combined with that of energy consumption, demands a different management of the energy system. In this work, we investigate the uncertainty of all variables combined, in order to take this variability into account in energy management.

Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.
Toward a unified model for sediment transport from terrestrial source to abyssal-plain sink
Authors: Shobe Charles M. , Braun Jean , Yuan Xiaoping , Campforts Benjamin , Guillocheau François , Robin Cécile
Published: March 2020

Marine stratigraphy contains time-resolved information about the erosion of continents and its tectonic and climatic drivers. Quantitatively inverting marine stratigraphy for long-term terrestrial erosion histories requires numerical models that encompass the entire source-to-sink (S2S) system. Because inversion schemes require many model realizations to constrain free parameters against a misfit function, S2S models must be efficient (both in terms of allowing large time steps and scaling well for large problems) and have only a few parameters. Accordingly, most previous S2S models have treated seafloor evolution as a diffusion problem where sediment flux depends linearly on local topographic gradient. Such approaches have shown success in shallow marine settings like the continental shelf. However, they are less likely to apply to deeper marine environments where large deposits are observed and where nonlocal sediment transport processes (e.g., turbidity currents or marine debris flows) dominate sediment fluxes.

We present a unified modeling approach for coupling terrestrial and marine erosion, sediment transport, and deposition from the continent to the abyssal plain. Our model is based on the erosion-deposition family of models, where sediment flux is tracked across the landscape and seascape. Above sea level, erosion and deposition depend on river discharge, local slope, and sediment flux. Below sea level, local slope and sediment flux drive topographic change. The equations governing the terrestrial and marine domains take the same basic form such that a single semi-implicit numerical solution based on Gauss-Seidel iteration can be used across the whole S2S system. The solution scheme is near O(N) complexity in that the number of iterations required typically does not increase significantly with increasing grid resolution. The S2S model contains only five total parameters. We show preliminary analytical and numerical results and sensitivity analyses, and discuss the applicability of the model for the efficient inversion of deep marine stratigraphic data.
Changes of hydrological regime in the mountain catchments of the Crimean Peninsula
Authors: Zemlianskova Anastasiia , Makarieva Olga , Nesterova Nataliia , Arkhipov Danil
Published: March 2020

Crimean water resources are unevenly distributed and mainly generated at the slopes of the Crimean Mountains affecting water supply of population and industry of the peninsula. The study of water resources has been limited for the last 30 years due to political situation and little quantitative information is available about climate change impact on hydrological regime of Crimean rivers. The aim of the study was the assessment of current flow characteristics for three rivers originating from the Crimean Mountains (the Derekoyka River at Yalta; 49.7 km2, the Demerdjy River at Alyshta, 53 km2; the Kokkozka River at Golybinka, 83.6 km2) and their comparison to the historical period (1960-1990) data. The study area is characterized by a Mediterranean climate and has a pronounced high-altitude zoning. Main vegetation type is the oak forests and shrubs. The highest elevation of the slopes reaches 1500 m.

Due to the lack of hydrological data for the last 30 years, the assessment of current flow characteristics was conducted based on hydrological modelling and observed meteorological data. The hydrological model Hydrograph was used in the study. The model was successfully used for the simulations of streamflow in similar climate for the basins of the Black Sea coast of Russia (Makarieva et al., 2018; 2019). The model was parametrized based on the data on typical landscapes of the studied area. The verification of streamflow and water balance simulation results was conducted for the historical period (1960-1990). The model was used to produce streamflow hydrographs for the period of 1991-2018 based on meteorological data. The changes of hydrological regime of Crimean rivers was assessed in comparison with historical period. The results of the study will be presented.
A new joint IAG-IASPEI sub-commission for Seismogeodesy
Authors: Nocquet Jean-Mathieu , Nishimura Takuya , Bruni Sara , Zerbini Susanna , Ozener Haluk
Published: March 2020

Thanks to both technological evolution and analysis improvement in the past decades, space geodesy can now monitor crustal movements of a few millimeters over time opening new prospects for the study of earthquakes. However, fully exploiting the potential of geodetic measurements is subject to their further integration with seismological analysis and requires the development of a multidisciplinary approach. The new joint IAG-IASPEI sub-commission on Seismogeodesy aims to facilitate the cooperation between the geodetic and the seismological communities in order to improve our current understanding of the different processes leading to earthquakes.

The new Seismogeodesy sub-commission will focus on both observational challenges and theoretical aspects. Particular effort will be dedicated to identifying gaps of knowledge and opportunity for progress. Specifically, the sub-commission will:
* actively encourage the cooperation between all geoscientists studying the plate boundary deformation zones, by promoting the exploitation of synergies between different fields;
*  work to reinforce collocated and integrated geodetic and seismological monitoring of seismically active areas, inland and off-shore by increasing and/or developing infrastructures dedicated to broadband observations from the seismic wave band to the permanent displacement;
* be a reference group for the integration of the most advanced geodetic and seismological techniques by developing consistent methodologies for data reduction, analysis, integration, and interpretation;
* act as a forum for discussion and scientific support for international geoscientists investigating the kinematics and mechanics of the plate boundary deformation zone;
* promote the use of standard procedures for geodetic data acquisition, quality evaluation, and processing, particularly GNSS data and InSAR data;
* promote earthquake geodesy, the study of seismically active regions with large earthquake potential, and geodetic application to early warning system of earthquakes and tsunamis for hazard mitigation;
* promote the role of geodesy in tectonic studies for understanding the seismic cycle, transient and instantaneous deformation, and creeping versus seismic slip on faults.
* facilitate and stimulate the integrated exploitation of large data sets, using Machine Learning and Data Mining
* support the organization of periodic workshops, meetings, summer schools with special emphasis on interdisciplinary research and interpretation and modeling issues
* help to the emergence of a new generation of researchers in Seismogeodesy worldwide

We invite any researcher interested in Seismogeodesy to join us and have a fruitful discussion in front of our poster.  
Assessing the impact of rainfall seasonality anomalies on catchment-scale water resources availability
Authors: Romano Nunzio , Allocca Carolina , Deidda Roberto , Nasta Paolo
Published: March 2020

Water balance components depend on annual rainfall amount and seasonality in Mediterranean catchments. A high percentage of the annual rainfall occurs between late fall and early spring and feeds natural and artificial water reservoirs. This amount of water stored in the mild-rainy season is used to offset rainfall shortages in the hot-dry season (between late spring and early fall). Observed seasonal anomalies in historical records are quite episodic, but an increase of their frequency might exacerbate water stress or water excess if the rainy season shortens or extends its duration, e.g. due to climate change. Hydrological models are useful tools to assess the impact of seasonal anomalies on the water balance components and this study evaluates the sensitivity of water yield, evapotranspiration and groundwater recharge on changes in rainfall seasonality by using the Soil Water Assessment Tool (SWAT) model. The study area is the Upper Alento River Catchment (UARC) in southern Italy where a long time-series of daily rainfall is available from 1920 to 2018. To assess seasonality anomalies, we compare two approaches: a “static” approach based on the Standardized Precipitation Index (SPI), and a “dynamic” approach that identifies the rainy season by considering rainfall magnitude, timing, and duration. The former approach rigidly selects three seasonal features, namely rainy, dry, and transition seasons, the latter being occasionally characterized by similar properties to the rainy or dry periods. The “dynamic” approach, instead, is based on a time-variant duration of the rainy season and enables to corroborate the aforementioned results within a probabilistic framework. A dry seasonal anomaly is characterized by a decrease of 241 mm in annual average rainfall inducing a concurrent decrease of 116 mm in annual average water yield, 60 mm in actual evapotranspiration and 66 mm in groundwater recharge. We show that the Budyko curve is sensitive to the seasonality regime in UARC by questioning the implicit assumption of temporal steady-state between annual average dryness and evaporative index. Although the duration of the rainy season does not exert a major control on water balance, we have been able to identify seasonal-dependent regression equations linking water yield to dryness index over the rainy season.
Automatic detection of volcanic eruptions in Doppler radar observations using a neural network approach
Authors: Hort Matthias , Uhle Daniel , Venegas Fabio , Scharff Lea , Walda Jan , Avard Geoffroy
Published: March 2020

Immediate detection of volcanic eruptions is essential when trying to mitigate the impact on the health of people living in the vicinity of a volcano or the impact on infrastructure and aviation. Eruption detection is most often done by either visual observation or the analysis of acoustic data. While visual observation is often difficult due to environmental conditions, infrasound data usually provide the onset of an event. Doppler radar data, admittedly not available for a lot of volcanoes, however, provide information on the dynamics of the eruption and the amount of material released. Eruptions can be easily detected in the data by visual analysis and here we present a neural network approach for the automatic detection of eruptions in Doppler radar data. We use data recorded at Colima volcano in Mexico in 2014/2015 and a data set recorded at Turrialba volcano between 2017 and 2019. In a first step we picked eruptions, rain and typical noise in both data sets, which were the used for training two networks (training data set) and testing the performance of the network using a separate test data set. The accuracy for classifying the different type of signals was between 95 and 98% for both data sets, which we consider quite successful. In case of the Turriabla data set eruptions were picked based on observations of OVSICORI data. When classifying the complete data set we have from Turriabla using the trained network, an additional 40 eruptions were found, which were not in the OVSICORI catalogue.

In most cases data from the instruments are transmitted to an observatory by radio, so the amount of data available is an issue. We therefore tested by what amount the data could be reduced to still be able to successfully detect an eruption. We also kept the network as small as possible to ideally run it on a small computer (e.g. a Rasberry Pi architecture) for eruption detection on site, so only the information that an eruption is detected needs to be transmitted.
Innovating surface and in-mine seismic exploration solutions
Authors: Malehmir Alireza , Dynesius Lars , Marsden Paul , Buske Stefan , Pacheco Nelson , Markovic-Juhlin Magdalena , Brodic Bojan , Donoso George , Pertuz Tatiana , de Kunder Richard , Sito Lukasz , Juhlin Christopher
Published: March 2020

Mineral exploration industry needs to push its technological advancement towards finding the so-called critical raw materials. These materials are fundamental for our green technologies and help accelerate the energy transition towards decarbonisation. While in-mine and near-mine exploration will be more convenient in the short term, providing fresh raw materials and mines in greenfield or brownfield areas must not be forgotten in the longer term. As the chase for mineral deposits becomes deeper, seismic methods play a greater role for exploring at depth. Through a series of experiments conducted within the EU-funded Smart Exploration project, we have innovated a number of hardware and methodological solutions for in-mine as well as brownfield seismic exploration. Along with these, legacy data have also been recovered, reprocessed and their values for mineral exploration illustrated. The legacy data examples are from the Ludvika Mines (Nordic Iron Ore AB) of central Sweden and Neves-Corvo (Somincor-Lundin Mining) of southern Portugal.

In particular, through the development of a GPS-time system, we have managed to acquire a globally unique semi3D in-mine and surface seismic dataset at the world-class Neves-Corvo mine. This helped to utilize four exploration tunnels at 600 m depth and two receiver lines on the surface allowing over 1000 recorders to be synchronized for down-tunnel exploration. A broadband electromagnetic-based seismic source (7 kN or 1.5t), developed also in the project, was used as the seismic source.

In central Sweden, at an iron-oxide mining site of Nordic Iron Ore company, 2D seismic profiles helped to suggest potential resources in the down-dip continuation of the known deposits but also in their footwall. A follow-up and more recent survey employed over 1250 seismic recorders and a 32t vibrator to acquire a sparse 2 by 2 km seismic dataset. The data show great quality and allow to image lateral extent of the deposits and crosscutting reflections that may be important factors for mine planning and understanding structural evolution of the deposits. The broadband seismic source was also tested at the site along the existing 2D profiles with raw data already showing a number of reflections interpreted to be from the mineralization. This survey further illustrates that the seismic source functions well and has a great potential for hard rock seismic applications. 

Acknowledgements: This work was supported by the Smart ExplorationTM project. Smart Exploration has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 775971.