bluuebunny/crossref_metadata_2025 huggingface dataset:
Accurate Quantification of Seamount Volcanism in Abyssal  Sediments Using Gaussian Process Regression
Authors: Zhao Yanghui , Riel Bryan
Published: March 2021

Seamounts are isolated, underwater volcanoes with more than 100 m in relief. This kind of volcanism arises from the lithosphere or asthenosphere through fractional melt and is a direct manifestation of the tectonic-magmatic activity of the interior of the earth. While previous studies have quantified the global distribution of seamounts by their physical properties (e.g., height, semimajor axis, angle, etc.), these studies usually (1) assume an elliptical cone to model seamount shape, and (2) neglect the sediment coverage on the seamount, which results in significant uncertainties when comparing properties of seamounts near the continents covered with thick sediments to those in the open ocean covered with thin sediments.

We apply a large-scale Gaussian Process regression to recover the seamount topography covered by sediments for an accurate distribution of volcanism in the South China Sea basin (with an average thickness of 1.5 km sediments) and the entire Pacific Ocean (with < 300 m thick sediments). Specifically, we first use Tophat filtering to isolate short-spatial-wavelength seamount topography above long-wavelength seafloor. Subsequently, we apply Gaussian Process regression to learn the seamount structure above the seafloor in order to extrapolate the structure beneath the sediment. Lastly, we compute the seamount volume above the sedimentary basement (i.e., top boundary of the oceanic crust) and compare it to the volume above the seafloor. Our results show that for the South China Sea, there is a significant increase in estimated seamount volume above the basement as compared to above the seafloor. For the Pacific Ocean, due to the thin sediment coverage, we observe negligible differences between the two volume estimates. Thus, analysis of seamount properties in marginal basins in the West Pacific with thick sediment coverage can lead to significant underestimation of volcanism intensity if sub-seafloor topography is not accounted for. For these marginal basins, without massive hotspots or apparent evidence of mantle plumes, normal plate tectonic processes are likely responsible for the intensive oceanic volcanism.
Ecosystem services provided by groundwater dependent wetlands in Irish karst 
Authors: Delle Grazie Fabio Massimo , Gill Laurence
Published: March 2021

Turloughs, the focus of this study, are ephemeral lakes and they are mostly groundwater dependent. They are present mostly in Ireland and have been compared hydrologically to polje for the period inundation and lacustrine deposits. They are flooded for some periods across the year (typically in the winter) but usually dry up in summer months. Turloughs are protected under the Water Framework Directive (WFD, Directive 2000/60/EC) and the EU Habitats Directive (92/43/EEC). Ecosystem services can be defined as the conditions and processes through which natural ecosystems sustain and fulfil human life. These can be classified as provisioning, regulating, and cultural and examples of them are water and raw materials production, flood risk attenuation, carbon sequestration. The determination of the ecosystem services can help analyse different scenarios linked to pressures like road drainage schemes, water supply and wastewater disposal.

 

Seven turloughs (Blackrock, Lough Coy, Lough Aleenaun, Lough Gealain, Caranavoodaun, Skealoghan, Coolcam) have been selected from a previous study and samples of waters were collected monthly to determine carbon and nutrients. Carbon and nutrients were also determined on soil samples taken from the turlough catchment. The overwhelming majority of wetlands act as long-term sinks for CO2. To determine whether this is the case for some of the turloughs in the study, greenhouse gases from soils and water were monitored and balances were worked out. Ecosystem services were quantified through various models which had to be adapted to the special conditions present in the turloughs.

 

The seven turloughs have different hydrological characteristics. Hydrology is the main driver of vegetation distribution therefore ommunities are distributed in zones arranged along the flooding gradient. Aquatic invertebrates also show a succession of communities through the hydroperiod.

 

The seven turloughs studied provide a variety of hydrological characteristics, habitat, soil and vegetation and offer different ecosystem services. Each ecosystem service was quantified using appropriate models. Almost all the turloughs are at risk from anthropic activities and potentially from climate change. Important ecosystem services for these turloughs are flood mitigation, nutrient retention, carbon sequestration, habitat preservation and recreational activities.
On the update of flood hazard and risk maps in the Po River District: results obtained for flood damage modelling
Authors: Molinari Daniela , Ballio Francesco ,   Flood damage group - Po River District's updating maps project
Published: March 2021

The European Floods Directive (2007/60/EC) requires that Member States develop flood hazard and risk maps, to be used as the information basis for the development of Flood Risk Management Plans, and to update them every 6 years. To support such a process, the Po River District Authority signed in May 2020 an agreement with 20 Italian Universities and the Italian National Research Council (CNR) with the aim of transferring the state of the art about hydrology (including climate change), hydraulics and damage modelling into the production of the new maps, to be delivered by December 2021. This contribution describes the activities done so far by the damage modelling group, composed by 8 Universities and CNR. The objective of the group is to provide an Information System able to perform a quantitative estimation of flood damage, overcoming the limitations of present maps where the evaluation of risk remains highly qualitative and subjective. Proper damage assessment tools were identified for all the five categories of exposed elements included in the Directive: population, infrastructures, economic activities, environmental and cultural heritage, and na-tech sites. These tools are thought to address specific requirements: (i) being valid/applicable for the whole area of the District, (ii) being based on standardised and institutional data, available at national level, (iii) being calibrated (and possibly validated) in the Italian context. A dedicated Geographical Information System is currently under development to support technicians in the application of proposed tools and in the visualisation and processing of damage assessment results.  The work done so far suggests that a quantitative estimation of damage is not yet possible for all the categories, rather three different levels of damage knowledge can be reached depending on the category and available data: quantitative, qualitative or descriptive (the latter being based on a deep investigation of historical data). Therefore, in order to get a total damage figure, the need arises of (i) comparing damage data with different metrics and (ii) comparing and weighting damage to different exposed categories, whose values may depend on objectives at stakes. A participatory process with final users will be then set up in the next year, to guarantee the usability and applicability of developed tools.
Impact of the Galileo constellation on GNSS Tropospheric Tomography
Authors: Adavi Zohreh , Weber Robert
Published: March 2021

GNSS Tomography is a promising tool to reconstruct the wet refractivity field (Nw) related to water vapor due to the continuous pass of GNSS rays through the atmosphere. To improve observation geometry compared to a sole GPS/ Glonass system scenario, applying further multi-GNSS observations in GNSS Tomography has become an essential research point in the recent decade. Therefore, the aim of this presentation is to investigate the impact of different constellations to solve the ill-posed inverse problem to retrieve a wet refractivity field by focusing on Galileo's effect on the accuracy of the estimated refractivity. Regarding this, the designed models loosely constrained due to provide an optimum situation for assessing the influence of Galileo constellation in the tomography solution. Test computations are based on data from a regional RTK-GNSS network close to Vienna operated by the Austrian power-supply company EVN (EnergieVersorgung Niederösterreich) and mostly located in the west part of Austria. The span DoYs 233-246 in August 2019 was chosen as a period of interest due to the high precipitation during that time. Consequently, we have considered the following processing schemes: 1- GPS+ Glonass (GR), 2- GPS+ Galileo (GE), and 3- GPS + Glonass + Galileo (GRE) to generate the reconstructed Nw field by means of the in-house Tomography software TOMTRP. Furthermore, as the Slant Tropospheric Delays (SWDs) and corresponding residuals are used as input data for GNSS tomography, so the impact of the mentioned schemes to estimate SWDs has been investigated here. Finally, in order to analyze the efficiency of the three schemes, the reconstructed refractivity profiles are compared to radiosonde profiles available in that area.
Proposed methodology for the assessment of groundwater chemical and quantitative status in the Republic of Belarus (in accordance with the principles of the EU Water Framework Directive)
Authors: Vasniova Olga , Biarozka Olga , Scheidleder Andreas , Humer Franko
Published: March 2021

Since 2018, the “European Union Water Initiative Plus for Eastern Partnership (EaP) Countries (EUWI+)” has been providing significant assistance in the development of a number of pilot projects focused on the phased implementation of the main provisions of the EU Water Framework Directive (WFD) related to groundwater monitoring in the Republic of Belarus. The implementation began with the identification (delineation) of groundwater bodies, their characterization, assessment and improvement of groundwater monitoring networks and several groundwater investigations in order to collect the necessary data to assess groundwater risk and status. Just recently, transboundary cooperation with Ukraine, resulted in the identification of common transboundary groundwater corridors and the proposal of a monitoring network for transboundary groundwater.

The next logical step in the implementation of the WFD is the assessment of the quantitative and qualitative groundwater status, which confirms whether the environmental objectives of the WFD for groundwater have been achieved. Thus, in 2020, a draft methodology for assessing the groundwater status in the Republic of Belarus in accordance with the principles of the WFD was developed.

The elaborated draft methodology defines criteria for the assessment of groundwater quantitative and qualitative status (“good” and “poor”) and the assessment of the risk (“at risk” and “not at risk”) whether the environmental objectives of the WFD cannot be achieved. The criteria consider all relevant and related national legislation and legal provisions which are in force and the assessments follow step-by-step implementation procedures.

A preliminary testing of the proposed methodology and a list of open issues that need to be solved complete the work.

The proposed methodological approach is a first attempt and needs to be thoroughly tested with available groundwater monitoring data in the coming months, both for groundwater bodies with dense monitoring networks and groundwater bodies with limited groundwater monitoring, Finally, the approach needs to be intensively discussed at national level before being implemented into national legislation.
The role of biochar particle size and hydrophobicity in improving soil hydraulic properties
Authors: Edeh Ifeoma , Mašek Ondřej
Published: March 2021

The physical properties of biochar have been shown to dramatically influence its performance as a soil amendment. Biochar particle size is one of key parameters, as it controls its specific surface area, shape, and pore distribution. Therefore, this study assessed the role of biochar particle size and hydrophobicity in controlling soil water movement and retention. Softwood pellet biochar in five particle size ranges (>2 mm, 2 – 0.5 mm, 0.5 – 0.25 mm, 0.25 – 0.063mm and <0.063 mm) was used for the experiment. These particle sizes were tested on 2 soil types (sandy loam and loamy sand) at four different application rates (1, 2, 4 and 8%).  Our results showed that biochar hydrophobicity increased with decreasing biochar particle size, leading to a reduction in its water retention capacity. The effect of biochar on soil hydraulic properties varied with different rate of application and particle sizes. With increasing rate of application, water retention increased while hydraulic conductivity decreased. Water content at field capacity, permanent wilting point, and the available water content increased with increasing biochar particle size. The soil hydraulic conductivity increased with decreasing particle sizes apart from biochar particles <0.063mm which showed a significant (p≤0.05) decrease compared to the larger particle sizes. The results clearly showed that both biochar intra-porosity and inter-porosity are important factors affecting soil hydraulic properties. Biochar interpores affected mainly hydraulic conductivity, both interpores and intrapores controlled soil water retention properties. Our results suggest that for a more effective increase in soil water retention in sandy loam and loamy sand, the use of hydrophilic biochar with high intra-porosity is recommended.
Quaternary sediment sources, sinks and transport pathways in the Black Sea-Caspian Sea region
Authors: Költringer Chiara , Stevens Thomas , Lindner Martin , Baykal Yunus , Kurbanov Redzhep
Published: March 2021

The Black Sea-Caspian Sea region is a vast and geomorphologically variable area where sea level changes, large rivers and their migration, and numerous interacting climate systems and aeolian regimes lead to a highly dynamic and complex situation of sediment supply and reworking. The area is blanketed by extensive loessic and sandy aeolian deposits, extending from northern Iran, through the Caucasus piedmont, Caspian lowland, and into the Crimea and East European Plain, as well as marine, fluvial and alluvial sediments. While loess deposits are especially extensive adjacent to major rivers such as the Volga, Don and Dnieper, the provenance, transport and nature of loess in this complex and highly dynamic environment remains poorly known.

Both, the Black Sea and the Caspian Sea experienced several transgressive and regressive phases during the Pleistocene, with temporary connections occurring over the Manych passage and resulting in the formation of marine terraces over a wide area, which are dry at present. The sea levels of the Caspian and Black seas and long-range north to south sediment transport are heavily influenced by the great rivers draining the previously glaciated East European Plain, the Volga, Don and Dnieper. In addition, the Black Sea and Caspian Sea are surrounded by mountain ranges, with the Carpathians in the west, the North Anatolian Mountains south of the Black Sea, the Crimea-Caucasus orogen and the Alborz mountains extending from northeast of the Black Sea to south of the Caspian Sea, all of which may act as sediment source regions. Furthermore, more distal orogens lying to the east, such as the Ural, Altai, Pamir and Kopet-Dag, and their palaeo-drainage systems, also represent potential sediment source areas for the Caspian Sea basin. The Karakum desert lying to the east of the south Caspian combines the potential of being a sediment sink for material from these mountains, as well as a secondary source for the Caspian Sea and the large loess area in northern Iran.
Here we apply U-Pb dating of detrital zircons to constrain the major sediment generating regions in this large area, transport pathways, and to further address the implications for sediment generation and cycling. In addition to loess, we aim to constrain the sediment transport pathways both for fluvial, marine and aeolian systems more generally, and to reconstruct the network of sediment routing in the Black Sea-Caspian Sea region. Our results reveal great spatial variability in zircon provenance and indicate the contribution of multiple source regions and transport pathways for most analysed samples and sites. Rivers have the strongest control on sediment erosion and distribution and are also in control of aeolian deposits, while not much sediment mixing seems to occur within the sea basins.
The importance of green roofs in an urban Water-Energy-Food-Ecosystem nexus context
Authors: Cristiano Elena , Deidda Roberto , Viola Francesco
Published: March 2021

The modern society is facing new environmental and socio-economic challenges: population is growing fast, and it is projected to continue with this trend, reaching 9.8 billion of people by 2050, with 2/3 of them living in cities. Moreover, climate changes are leading to an increase of hot and dry periods and of short but intense rainfall events, forcing policy makers to rethink to the water management system. For these reasons, it is important to integrate in the urban planning, sustainable solutions that can help dealing with these new challenges. In this context, green roofs are powerful and flexible tools, that can play a fundamental role in the creation and development of smart and resilient cities. So far, green roofs have been generally investigated focusing on one single field at the time, following a so called “silo approach”. This approach, however, does not allow to highlight the interconnections and feedback between the different sectors, limiting the understanding of the potential of this tool. An integrated water-energy-food-ecosystem nexus approach is hence required to fully explore all the potential benefits of a large-scale installation of this tool. This work presents a review of green roofs’ benefits, following an integrated water-energy-food-ecosystem approach, with the aim to identify the potential positive impacts for the development of sustainable and resilient cities. Green roofs present multiple benefits for the urban environment, which are in line with the Development Goals proposed in the Sustainable Agenda 2030 (SDGs). Green roofs can, for example, mitigate pluvial floods, adapting to climate changes (SDG13: Climate Action) and contrasting the urbanization (SDG11: Sustainable Cities and Communities). The installation of these tools on the rooftops guarantee thermal insulation for the building, reducing the energy consumption for heating and cooling systems (SDG7: Affordable and Clean Energy). Thanks to the potential applicability of urban agriculture on its surface, green roofs can reduce the population food demand (SDG2: Zero Hunger), especially in poor countries, where many people have limited or no access to food. Moreover, the harvested rainwater, if properly stored and treated, can be reused for several domestic purposes, reducing the pressure on the water supply system and consequently increasing the availability of clean water (SDG6: Clean Water and Sanitation).The installation of vegetation in urban areas partially aims to restore the natural conditions, increasing the biodiversity and attracting different species of insects and small vertebrates, which are fundamental to guarantee maintenance of the ecosystem (SDG15: Life on Land). Moreover, the installation of this tool in an urban environment contributes to improve the mental and physical well-being of citizens (SDG3: Good Health and Well-being), which is particularly relevant in relation to the health crisis caused by the COVID-19 pandemic.
Relative impacts of climate change and anthropogenic forcing on karst spring discharge forecasting of a Mediterranean catchment
Authors: Sivelle Vianney , Jourde Hervé , Bittner Daniel , Mazzilli Naomi , Tramblay Yves
Published: March 2021

The Mediterranean region is identified as a climate change hotspot, where future scenarios indicate an increase of temperature associated with a decrease of precipitation. Providing future scenarios of water resource availability considering both climate and anthropogenic changes on karst catchments remains a major challenge for hydrological sciences. The study concerns the Oeillal spring, which is one outlet of the karst catchment associated with the Fonfroide-Monredon massif (southern France), mainly composed by Jurassic limestones. We assess the relative effects of climate changes and anthropogenic forcing on the karst spring discharge by coupling 12 climate model simulations (GCM/RCM) under two emission scenarios (RCP 4.5 and RCP 8.5) with 3 hydrological models and considering 4 scenarios of groundwater abstraction for drinking water supply (no abstraction, present-day abstraction, +50 % abstraction and +100 % abstraction at horizon 2100).  We find that climate change has a major effect on the future evolution of the Oeillal spring’s discharge and that groundwater abstraction constitutes a secondary but non-negligible factor, which increases the occurrence of dry up of the Oeillal spring.
Data-driven stochastic model for cross-interacting processes with different time scales
Authors: Gavrilov Andrey , Seleznev Aleksei , Mukhin Dmitry , Feigin Alexander
Published: March 2021

The problem of modeling interaction between processes with different time scales is very important in geoscience. In this report, we propose a new form of empirical evolution operator model based on the analysis of multiple time series representing processes with different time scales. We assume that the time series are given on the same time interval.

To construct the model, we extend the previously developed general form of nonlinear stochastic model based on artificial neural networks and designed for the case of time series with constant sampling interval [1]. This sampling interval is related to the main time scale of the process under consideration, which is described by the deterministic component of the model, while the faster time scales are modeled by its stochastic component, possibly depending on the system’s state. This model also includes slower processes in the form of weak time-dependence, as well as external forcing. The structure of the model is optimized using Bayesian approach [1]. The model has proven its efficiency in a number of applications [2-4].

The idea of modeling time series with different time scales is to formulate the above-described model individually for each time scale, and then to include the parameterized influence of the other time scales in it. Particularly, the influence of “slower” time series is included in the form of parameter trends, and the influence of “faster” time series is included by time-averaging their statistics. The algorithm and first results of comparison between the new model and the model without cross-interactions will be discussed.

The work was supported by the Russian Science Foundation (Grant No. 20-62-46056).

1. Gavrilov, A., Loskutov, E., & Mukhin, D. (2017). Bayesian optimization of empirical model with state-dependent stochastic forcing. Chaos, Solitons & Fractals, 104, 327–337. http://doi.org/10.1016/j.chaos.2017.08.032

2. Mukhin, D., Kondrashov, D., Loskutov, E., Gavrilov, A., Feigin, A., & Ghil, M. (2015). Predicting Critical Transitions in ENSO models. Part II: Spatially Dependent Models. Journal of Climate, 28(5), 1962–1976. http://doi.org/10.1175/JCLI-D-14-00240.1

3. Gavrilov, A., Seleznev, A., Mukhin, D., Loskutov, E., Feigin, A., & Kurths, J. (2019). Linear dynamical modes as new variables for data-driven ENSO forecast. Climate Dynamics, 52(3–4), 2199–2216. http://doi.org/10.1007/s00382-018-4255-7

4. Mukhin, D., Gavrilov, A., Loskutov, E., Kurths, J., & Feigin, A. (2019). Bayesian Data Analysis for Revealing Causes of the Middle Pleistocene Transition. Scientific Reports, 9(1), 7328. http://doi.org/10.1038/s41598-019-43867-3
Impact of climate change on renewable energy over the Mediterranean and Canary Islands: SOCLIMPACT H2020 project.
Authors: Gutiérrez Claudia , de la Vara Alba , González-Alemán Juan Jesús , Gaertner Miguel Ángel
Published: March 2021

The enhanced vulnerability of insular regions to climate change highlights the importance of undertaking adaptation and mitigation strategies according to the specific singularities of the islands. Islands are highly dependent on energy imports and the transition to a system with higher shares of renewable energies, in order to reduce greenhouse gas emissions in these regions, can also reduce the external energy dependence. In this context, the assessment of the impact of climate change on renewable energy resources during the 21st century is crucial for policymakers and stakeholders, due to the increasing vulnerability of the system to climate variability. The aim of this work is to provide an overview of wind and photovoltaic (PV) resources, their variability and complementarity between them, as well as their future changes, in the Euro-Mediterranean and Canary islands. Due to the limitations in land surface availability in the islands for the installation of renewable energy capacity, the analysis is extended to offshore wind and photovoltaic energy, which may have an important role in the future increases of renewable energy share. Variability is assessed through the analysis of energy droughts (low-productivity periods). In addition, a case study for optimization of wind and solar combination over the Canary islands is performed. In that sense, a sensitivity test is developed to find the optimal combination of PV and wind that reduce energy droughts and the persistence of that conditions at a local scale. To that end, we use climate variables from a series of regional climate simulations derived from Euro-CORDEX and MENA-CORDEX for the RCP2.6 and RCP8.5 emission scenarios and for the periods 2046-2065 and 2081-2100. The obtained results are very dependent on the region analyzed. Whereas an overall decrease is projected in wind resource over the Mediterranean islands for the future, an increase is projected for the Canarian archipelago. Changes in PV productivity are small in any case, as well as variability changes. These results, which are part of the SOCLIMPACT H2020 project, highlight the importance of targeting climate information and give condensed and valuable data to facilitate climate-related policy decision making for decarbonization and Blue Growth in the islands.
Reuse of medieval bricks as important limitation for construction of geomagnetic secular variation curves based on archeomagnetic studies of brick buildings in Poland. 
Authors: Nawrocki Jerzy , Standzikowski Karol , Werner Tomasz , Łanczont Maria , Gancarski Jan , Gil Zdzisław
Published: March 2021

The bricks can be one of the best material for archeomagnetic studies. Their backing technique (i.e. horizontal location in the furnace) allow to determine also the value of inclination of geomagnetic field.  However, reuse of older bricks for the construction of newer objects can limit the utility of this material in archeomagnetic studies. A set of the brick samples from 26 historical buildings in SE Poland was taken for archeomagnetic investigations. As a result of this study, the secular variations of palaeointensity and inclination of the geomagnetic field from 1200 to 1800 AD were defined for this part of Poland. The paleointensity of geomagnetic field  was determined using the IZZI-Thellier-Thellier protocol. The course of the new regional palaeosecular curves is approximately the same as so far obtained in other parts of Europe. Data obtained from four brick buildings, however, do not fit substantially to the reference European curves. The remarkable difference  is a rapid and deeper drop of inclination and significantly higher than expected values of  palaeointensity. These features indicate that bricks used for the construction of these buildings (dated on XVI – XVII centuries) were taken from older brick constructions, most probably from the Gothic time (XIII/XIV c.). We compared our data with the earlier data obtained from brick buildings in N Poland. The regional archeomagnetic curves calculated for these two regions of Poland are completely different in their segments as old as the first half of the 18th century. This fact could be explained by the reuse of medieval bricks during the construction of studied objects from N Poland (dated on the first half of the 18th century) and applied for the construction of reference curve or by later secondary heating of original bricks.

This research was supported by  the National Science Centre of Poland (project no: UMO-2016/23/B/ST10/0129).
Serpentine crack-seal veins: a unique record of fluid conditions during faulting
Authors: Tarling Matthew S. , Smith Steven A.F. , Rooney Jeremy S. , Viti Cecilia , Gordon Keith C.
Published: March 2021

Serpentine veins are ubiquitous in hydrated and deformed ultramafic rocks, and have previously been used to track fault kinematics and understand the evolution of environmental conditions during vein formation. However, difficulties in unambiguously identifying and mapping serpentine types at sub-micron to mm scales has limited our understanding of vein precipitation kinetics and growth histories. Using recently developed techniques of Raman spectroscopy mapping, combined with scanning- and transmission-electron microscopy, we describe a new type of mineralogically banded serpentine crack-seal vein in six samples from different settings around the world. In all of the studied samples, individual bands comprise a thin layer (~0.4–2 µm) dominated by chrysotile and a much thicker layer (~0.5–30 µm) dominated by polygonal serpentine/lizardite. Existing field and experimental data suggest that disequilibrium conditions immediately following crack opening may favour rapid precipitation of chrysotile along one of the crack margins. Subsequently, diffusional transport of elements favours slower precipitation of polygonal serpentine/lizardite which leads to crack sealing. The similarities in layer thicknesses and mineralogy exhibited by samples collected from extension and shear veins, dilational jogs, foliation surfaces, and the margins of phacoids, suggest that a common set of processes involving crack opening and sealing are active in a range of different structural sites within serpentinite-dominated shear zones, potentially associated with frequent and repetitive stress drops such as those recorded during episodic tremor and slow slip.
Anomalous propagation of medium scale GWs along neutral winds
Authors: Rusz Jan , Chum Jaroslav , Baše Jiří
Published: March 2021

Azimuth of medium scale gravity waves (GWs) propagation in the thermosphere/ionosphere fundamentally depends on the daytime and day of year. Previous studies show that the GWs mostly propagate against the predominant direction of neutral winds in the ionosphere. However, several cases of propagation along the wind direction have also been identified, specifically around the equinoxes. The analysis is based on remote observation of the ionosphere using multi–frequency and multipoint continuous Doppler sounding. The network consists of at least three spatially separated sounding paths (transmitter-receiver pairs) at three frequencies, situated in the western part of the Czech Republic. The apparent horizontal velocity and azimuth of GWs are derived from the time shifts observed for different measuring paths. The HWM14 neutral wind model is used for comparison of neutral winds with the observed phase speeds of GWs. Cases of anomalous propagation of GWs along the direction of neutral winds are analyzed. It is shown that the observed GW periods can be substantially shorter than the intrinsic periods in the wind-rest frame owing to Doppler shift.
Benefit of poroelasticity for geothermal research
Authors: Kretz Bianca , Freeden Willi , Michel Volker
Published: March 2021

For geothermal purposes (heat and electricity generation) it is necessary to have an aquifer from which the contained hot water can be lifted by drilling. The exchange of the hot water against some cooled off water has an effect on the surrounding material and displacement of the material has an influence on the pore pressure and the water. Poroelasticity can model these influencing effects by partial differential equations.

We want to apply poroelasticity in geothermal research by so-called multiscale modelling. Scaling functions and wavelets are constructed with the help of the fundamental solutions. A related method has been previously used for the Laplace, the Helmholtz and the d'Alembert equation (cf. [2],[4],[5]) as well as for the Cauchy-Navier equation, where the latter requires a tensor-valued ansatz (cf. [3]). We pursue this concept to develop such an approach for poroelasticity, where a fundamental solution tensor is known (cf. [1]).

The aim of this multiscale modelling is to convolve the constructed scaling functions with the data of the displacement $u$ and the pressure $p$. With this, we have the opportunity to visualize structures in the data that cannot be seen in the whole data. Especially, the difference of the convolution of two consecutive scaling functions is expected to reveal detail structures.

For the theoretical part, we can show that the scaling functions fulfill the property of an approximate identity. Furthermore, with numerical results we want to show the decomposition.

References

[1] M. Augustin: A method of fundamental solutions in poroelasticity to model the stress field in geothermal reservoirs, PhD Thesis, University of Kaiserslautern, 2015, Birkhäuser, New York, 2015.

[2] C. Blick, Multiscale potential methods in geothermal research: decorrelation reflected post-processing and locally based inversion, PhD Thesis, Geomathematics Group, Department of Mathematics, University of Kaiserslautern, 2015.

[3] C. Blick, S. Eberle, Multiscale density decorrelation by Cauchy-Navier wavelets, Int. J. Geomath. 10, 2019, article 24.

[4] C. Blick, W. Freeden, H. Nutz: Feature extraction of geological signatures by multiscale gravimetry. Int. J. Geomath. 8: 57-83, 2017.

[5] W. Freeden, C. Blick: Signal decorrelation by means of multiscale methods, World of Mining, 65(5):304--317, 2013.
Impact of low-degree gravity field estimation in the SLR data processing of spherical satellites at AIUB
Authors: Geisser Linda , Meyer Ulrich , Arnold Daniel , Jäggi Adrian , Thaller Daniela
Published: March 2021

The Astronomical Institute of the University of Bern (AIUB) collaborates with the Federal Agency for Cartography and Geodesy (BKG) in Germany to develop new procedures to generate products for the International Laser Ranging Service (ILRS). In this framework the SLR processing of the standard ILRS weekly solutions of spherical geodetic satellites at AIUB, where the orbits are determined in 7-day arcs together with station coordinates and other geodetic parameters, is extended from LAGEOS-1/2 and the Etalon-1/2 satellites to also include the LARES satellite orbiting the Earth at much lower altitude. Since a lower orbit experiences a more variable enviroment, e.g. it is more sensitive to time-variable Earth's gravity field, the orbit parametrization has to be adapted and also the low degree spherical harmonic coefficients of Earth's gravity field have to be co-estimated. The impact of the gravity field estimation is studied by validating the quality of other geodetic parameters such as geocenter coordinates, Earth Rotation Parameters (ERPs) and station coordinates. The analysis of the influence of LARES on the SLR solution shows that a good datum definition is important.
Unravelling sediment connectivity during an extreme event in an Alpine catchment
Authors: Scorpio Vittoria , Cavalli Marco , Comiti Francesco , Steger Stefan
Published: March 2021

This work presents the results of the basin-scale analysis of sediment connectivity between hillslopes and the main channel during an extreme event in a mountain catchment. The Stolla basin (South Tyrol, Italy) was affected by a high-magnitude event in August 2017, during which the channel experienced widening and bed level changes and more than 600 debris flows, and landslides occurred in the basin.

Hillslope and channel processes were mapped and characterized by using geomorphological analysis of orthophotos and pre- and post-event Digital Terrain Models (DTMs). Mass wasting process connectivity was derived by combining field survey evidence and GIS analysis. The coupling between the debris flows and landslides and the main channel was also evaluated by applying the Index of sediment connectivity (IC) by Cavalli et al. (2013). Binary logistic regression and the receiver operating characteristic curve was used to define thresholds that allow to discriminate connected from disconnected debris flows and landslides, based on IC values with respect to the main channel of the Stolla stream.

First results indicate that the Stolla’s post-event channel width was up to five times the pre-event width. Channel widening occurred mainly through bank erosions, removals of riparian vegetation and over bank depositions.  Widening appeared to be accompanied by channel bed aggradation up to 1 m or incision up to -2 m. Depending on the morphological characteristics of the channel and of the valley, sediments were eroded from the banks, from the bed or were delivered by connected debris flows, landslides, and toe erosion processes. Statistical analyses indicate a high efficiency of the logistic regression model and the associated threshold to separate connected from disconnected debris flows and landslides using the IC as a predictor variable.
Carbon Monitor Gridded Dataset (CMGD), a near-real-time high resolution gridded CO2 emission estimates dataset
Authors: Dou Xinyu , Liu Zhu
Published: March 2021

The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO2) emissions. This research first presented near-real-time high-spatial-resolution(0.1°*0.1°) and high-temporal-resolution(daily) gridded estimates of CO2 emissions for different sectors named Carbon Monitor Gridded Dataset(CMGD). This dataset responds to the growing and urgent need for high-quality, fine-grained CO2 emission estimates to support global emissions monitoring on the refined spatial scale. CMGD is derived from our Carbon Monitor, a near-real-time daily dataset of global CO2 emission from fossil fuel and cement production, including detailed information in 6 sectors and main countries. Based on EDGAR v5.0 gridded CO2 emissions map and other geospatial proxies, we finally constructed CMGD with a high spatial resolution of 0.1 degree. Here, we provided the total emissions of specific countries and analyzed the countries with larger emissions (including the EU). Furthermore, we analyzed the daily emission changes of several typical cities around the world and provided insights on the contributions of various sectors. Through CMGD, we can get a much faster and more fine-grained overview, including timelines that show where and how emissions decreases have corresponded to lockdown measures at the finer spatial scales. The fine-grain and timeliness of CMGD emissions estimates will facilitate more local and adaptive management of CO2 emissions during both the pandemic recovery and the ongoing energy transition.
Assessment of a meteorological mesoscale model’s capability to simulate intra-urban thermal variability in a tropical city
Authors: Sanchez Beatriz , Roth Matthias , Simón-Moral Andrés , Martilli Alberto , Velasco Erik
Published: March 2021

Large spatial differences in canopy-layer air temperature are found across the city as a consequence of distinct urban morphologies and anthropogenic activities throughout the urban landscape. Model-based studies investigating the spatial and temporal variability of air temperature are commonly employed to assess heat mitigation strategies in cities. It is therefore important that models are capable to accurately predict air temperature variability across the city to account for the local climate context. This study explores the sensitivity of the Weather Research and Forecasting (WRF) model coupled with a multi-layer urban scheme (BEP-BEM) to simulate intra-urban variations of 2-m air temperature during different synoptic conditions in a tropical city, Singapore. An accurate representation of the real heterogeneous urban morphology of Singapore is implemented in the model. Two one-month long simulations are conducted for distinct synoptic weather conditions: (a) a relatively wet period during the SW monsoon and (b) a very dry period during the NE monsoon. The performance of the model is firstly evaluated against micrometeorological data collected by a tall eddy covariance flux tower in a representative low-rise residential neighbourhood. Overall good performance is obtained for wind speed and direction, turbulence parameters and surface energy balance components, in particular during dry conditions. Some difficulties are found in predicting intermittent cloud cover, which results in an overestimation of net radiation increasing model errors during the wetter period. Hence the comparison of 2-m air temperatures against observations results in slightly higher errors during the latter period (RMSE<2.3°C) compared to the dry period (RMSE<1.6°C) using data from nine locations with different urban morphologies. Notable underestimation (overestimation) is obtained for the nighttime temperature at the most densely built-up (rural) area. A significant logarithmic relation between minimum nocturnal temperature and average aspect ratio is nevertheless obtained for both observations and simulations. Further analysis during clear sky conditions in both periods reveals that the spatial distribution of the diurnal temperature range computed at the urban locations varies according to synoptic conditions. The present research demonstrates the capability of the model to predict the intra-urban variability across distinct urban morphologies, however, it fails to accurately capture absolute differences in air temperature.
A transient backward erosion piping model based on laminar flow transport equations
Authors: Wewer Manuel , Aguilar-López Juan Pablo , Kok Matthijs , Bogaard Thom
Published: March 2021

Backward erosion piping (BEP) has been proven to be one of the main failure mechanisms of water-retaining structures worldwide. Dikes, which are often built on sandy aquifers, are particularly vulnerable to this special type of internal erosion. In this research, we propose a numerical solution that combines a 2D Darcy groundwater solution with Exner’s 1D sediment transport mass conservation equation. The inclusion of criteria for incipient particle motion, as well as the linkage of the bedload transport rate to the pipe progression, enables us to build a stable time-dependent piping model. As an estimate of sediment transport, we tested four different empirical transport equations for laminar flow. The model performance was evaluated based on the results of a real-scale dike failure experiment. Through this, we were able to demonstrate the applicability of existing sediment transport equations to the description of particle motion during piping erosion. The proposed transient piping model not only predicts the pipe progression in time, it also allows for an identification of pore pressure transitions due to the erosion process. The main finding of the study is that from the four different modeling approaches for laminar flow, it is recommended to follow the approach of Yalin et al. (1963, 1979) to simulate backward erosion piping in dikes.
Training a convolutional neural network to conserve mass in data assimilation
Authors: Ruckstuhl Yvonne , Janjic Tijana , Rasp Stephan
Published: March 2021

In previous work, it was shown that preservation of physical properties  in the data assimilation framework can significantly reduce forecast errors. Proposed data assimilation methods, such as the quadratic programming ensemble (QPEns) that can impose such constraints on the calculation of the analysis, are computationally more expensive, severely limiting their application to high dimensional prediction systems as found in earth sciences. We therefore propose to use a convolutional neural network (CNN) trained on the difference between the analysis produced by a standard ensemble Kalman Filter (EnKF) and the QPEns to correct any violations of imposed constraints. On this poster, we focus on conservation of mass and show in an idealized setup that the hybrid of a CNN and the EnKF is capable of reducing analysis and background errors to the same level as the QPEns. 
Integrated modeling of water and heat fluxes in the Seine hydrosystem, France
Authors: Kilic Deniz , Rivière Agnès , Flipo Nicolas , Ducharne Agnès , Peylin Philippe , Goblet Patrick
Published: March 2021

Given the current climate and anthropogenic evolution, water management becomes one of the greatest challenges of the 21st century. Number of studies have analyzed observed hydrologic trends and their connections with the changing climate. Impacts include changes in runoff, river discharge and groundwater recharge. Water quality is also impacted, through its many facets including the water temperature. Despite the important progress made in climate modelling, the impact of the predicted global warming on hydrological processes remains uncertain; particularly, in large hydrosystems. The Seine River basin has a surface of 78,650 km², it includes the Seine River and its 50 tributaries, it is populated by 30% of France inhabitants. The Seine River basin crosses 14 departments and 4 regions, including the Paris metropolitan area. Climate change poses a vulnerability due to its potential political, social, and economic consequences in the Seine basin. The agricultural activities and number industries depend on water resources or are located on the river sides. Our ability to adapt water resource management strategies to the climate change depends on our ability to understand and estimate the actual evolution of water resource. 

The terrestrial water budget is now considered as a single continuum. This integrated conceptualisation needs to simulate the spatial and temporal dynamics of water exchanges between the surface and groundwater. Here we propose to improve the representation of the surface water budget with the goal to decrease the uncertainty of the whole water budget of the Seine hydrosystem. We used the process-based physical land surface model ORCHIDEE (tag 2.2) to estimate surface water budget and heat balance for the period 1980-2018. This application takes advantage of high resolution land-use and albedo maps from ESA-CCI database, and various soil map databases. The model was satisfactorily able to reproduce the discharges of each sub-catchment, the actual evapotranspiration fluxes and LAI. With these results, we are able to estimate the the partitioning of the surface water balance of each catchment of the Seine basin. These results have wide ranging implications such as the estimation of energy balance in the basin, the estimation of spatialisation of the aquifer recharge, and the feedback between aquifers and the surface.