bluuebunny/crossref_metadata_2025 huggingface dataset:
Weather data modelling for energy system models using machine learning
Authors: Kies Alexander , Srivastava Nishtha , Zhou Kai , Steinheimer Jan , Stoecker Horst
Published: March 2020

Weather data is essential to model and optimise energy systems, which are based on high shares of renewable generation sources. However, differences between data sources can be significant and often little emphasis is put on energy-related variables such as hub-height wind speeds.

In this work, we use generative adversarial networks (GAN), a class of machine learning systems, to model weather data for large-scale energy system models and optimise energy systems of different scales and sizes.

We show that generating weather data using GAN saves effort as required for processing large amounts of weather data and that it can reliably reproduce results from using weather data produced by numerical models.
The Crustal Structure of the Eastern Marmara Region Using Receiver Function Analysis
Authors: Büyükakpınar Pınar , Aktar Mustafa
Published: March 2020

This study focuses on the crust of the Eastern Marmara in order to understand of how much the structure is influenced by the tectonic history and also by the activity of the NAF. Recent studies have claimed that the crustal thickness varies significantly on the north and south of the NAF, which is assumed to indicate the separation line between Eurasian and Anatolian Plates. The present study aims to reevaluate the claim above, using newly available data and recently developed tools. The methods used during the study are the receiver function analysis and surface wave analysis. The first one is more intensively applied, since the second one only serves to introduce stability constraint in the inversions. Data are obtained from the permanent network of KOERI and from PIRES arrays.  The main result of the study indicates that the receiver functions for the stations close to the fault zone are essentially very different from the rest and should be treated separately. They show signs of complex 3D structures of which two were successfully analyzed by forward modeling (HRTX and ADVT). A dipping shallow layer is seen to satisfy the major part of the azimuthal variation at these two stations. For the stations off the fault on the other hand, the receiver functions show a more stable behavior and are analyzed successfully by classical methods. CCP stacking, H-k estimation, single and joint inversion with surface waves, are used for that purpose. The results obtained from these totally independent approaches are remarkably consistent with each other. It is observed that the crustal thickness does not vary significantly neither in the NS, nor in the SW direction. A deeper Moho can only be expected on two most NE stations where a gradual transition is more likely than a sharp boundary (SILT and KLYT). The structural trends, although not significant, are generally aligned in the EW direction.  In particular, a slower lower crust is observed in the southern stations, which is possibly linked to the mantle upwelling and thermal transient of the Aegean extension. Otherwise neither the velocity, nor the thickness of the crust does not imply any significant variation across the fault zone, as was previously claimed.
Alpha-Mendeleev Rise is a Eurasian aborted volcanic passive continental margin
Authors: Nikishin Anatoly , Cloetingh Sierd , Foulger Gillian , Freiman Sergey , Malyshev Nikolay , Petrov Eugene , Startseva Ksenia , Rodina Elizaveta , Verzhbitsky Vladimir
Published: March 2020

We report interpretations of regional seismic lines and new data of analyses of rocks from Alpha-Mendeleev Rise. A new magmatic province is documented at the bottom of the North Chukchi Basin. Seismic data demonstrate synrift basalt sequences (half-grabens with bright reflectors) and a number of intrusions. The seismic stratigraphic age of the magmatism is ca. 125-100 Ma. Seismic data show evidence of magmatism in the area of De Long High. Basalts have isotopic ages on De Long islands of ca. 130-105 Ma. A huge magmatic province exists in the Barents Sea. Seismic data show a basalt province to the SE from Franz Josef Land. The two-way travel time of the basalt unit is 100 ms. The age of the basalts is ca. 125 Ma from correlation with borehole data. The area is enriched by intrusions of the same age. Similar magmatic provinces are known on Svalbard and the Canadian Archipelago. We recognize half-grabens and/or SDR complexes along the Mendeleev Rise. The dip of SDRs is toward the Podvodnikov and Toll basins. The Mendeleev Rise has an axial line which separates differently dipping SDRs. Half-grabens are filled with clastic rocks and basalts with ages ca. 127-110 Ma (Skolotnev et al. in preparation, and our correlations with seismic data). The Podvodnikov and Toll basins have SDR complexes also. The dipping of the SDRs is toward the axial lines of these basins, and the lines are parallel to the Mendeleev Rise axial line. We propose that intraplate, ca. 125 Ma basalt magmatism started between the Eurasian continent (including the Lomonosov and Alpha-Mendeleev terranes) and the Canada Basin (which formed before 125 Ma). This was followed by concentration of rifting and magmatism along Alpha-Mendeleev Rise and the adjacent Podvodnikov, Nautilus and Toll basins. These processes were aborted at ca. 100 Ma as a result of plate kinematic reorganization. Additional intraplate magmatism took place at 90-80 Ma. We propose that Alpha-Mendeleev Rise is a Eurasian aborted double-sided volcanic passive continental margin with stretched and hyper-extended continental crust intruded by basalts. This work was supported by RFBR grants (18-05-70011 and 18-05-00495).
Shape asymmetry of rogue waves
Authors: Kokorina Anna , Slunyaev Alexey
Published: March 2020

Direct numerical simulations of the directional sea surface gravity waves are carried out within the framework of the primitive potential equations of hydrodynamics using the High Order Spectral Method. The data obtained for conditions of deep water, the JONSWAP spectrum, and various wave intensities are processed and the results are discussed. The statistical and spectral characteristics of the waves evolve over a long period. The particular asymmetry of the profiles of rogue waves is highlighted. We show that besides the conventional crest-to-trough asymmetry of nonlinear Stokes waves, the extreme events are characterized by a specific combination of the troughs adjacent to the large crest, so that the trough behind the crest is typically deeper than the preceding trough. Surprisingly, the extreme wave crest-to-trough asymmetry and the discrimination between the extreme wave troughs exhibit the tendency to grow when the angle spectrum broadens. This effect contradicts the expectation based on the Benjamin – Feir Index that broad-banded waves should behave similar to linear waves, and hence the asymmetries should diminish.

                                                                 

The research is supported by the RSF grant No. 19-12-00253.

 

A. Kokorina, A. Slunyaev, The effect of wave nonlinearity on the rogue wave lifetimes and shapes. Proc. 14th Int. MEDCOAST Congress on Coastal and Marine Sciences, Engineering, Management and Conservation (Ed. E. Ozhan), Vol. 2, 711-721 (2019).
Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data
Authors: Gido Nureldin , Amin Hadi , Bagherbandi Mohammad , Nilfouroushan Faramarz
Published: March 2020

Monitoring environmental hazards, due to natural and anthropogenic causes, is one of the important issues, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, e.g. the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this aspect. GRACE missions are dedicated to model the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects Synthetic Aperture Radar (SAR) data which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure, form compaction and consequently land subsidence occurs which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, i.e. Heglig, Bamboo, Neem, Diffra and Unity-area oil fields. Then we correlate the results with the available oil wells production data for the period of 2003-2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Due to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS change and extracted oil and water volumes. The trend of GWS changes due to water and oil depletion ranged from -18.5 to -6.2 mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using Persistent Scatterer Interferometry (PSI) method shows high rate of subsidence i.e. -24.5, -23.8, -14.2 and -6 mm/year over Heglig, Neem, Diffra and Unity-area oil fields respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.
Fluid flow through rock fractures undergoing chemical interactions: A look at pressure solution from an experimental perspective
Authors: Milsch Harald , Cheng Chaojie
Published: March 2020

Fluid transport within the Earth’s crust is predominantly controlled by planar void space like fractures and crack networks. Characterizing the time dependent hydro-mechanical properties of these rock-structural elements therefore is of paramount importance for natural geosystem understanding and geotechnical applications alike.

In this contribution we outline the protocol and results of a long term flow-through experiment of more than 4 months conducted with one single-fractured, pure quartz, and centimeter-sized Fontainebleau sandstone sample displaying very low matrix permeability.

The cylindrical sample was axially split to generate one single and rough tensile fracture and the obtained sample halves were manually offset in axial direction by 200 µm resulting in geometric mismatch of the two fracture faces yielding asperity contacts and high contact stresses upon loading.

The experiment was conducted at constant temperature (333 K) and pore fluid pressure (1 MPa), three different confining pressure levels (2, 18, and 30 MPa), and with two different fluids (deionized water and 0.3 mM SiO2 solution).

The sample was continuously flown through and the experimental procedure consisted of several successive stages during which confining pressure and fluid type were systematically varied in time intervals of several weeks each.

The experiment yielded results of continuous sample and fracture permeability measurements, the derivation of time dependent changes in hydraulic fracture aperture, a complete ICP-OES chemical analysis of Si concentrations in the effluent in one day time intervals, and a full before/after microstructural investigation of mechanical aperture, contact area ratio, as well as asperity and free fracture face morphology.

Overall, this experiment yields evidenced insights into the low-temperature dynamics of fracture permeability when, concurrently, chemical interactions between fluid and rock are taking place. Moreover, the investigations emphasize the role of pressure solution (creep) in this context as opposed to, e.g., free face dissolution or subcritical crack growth. Finally, conclusions are drawn on the rate-limiting sub-process of pressure solution with possible implications for fluid history matching in quartz-rich fractured rock masses.
Combination of GNSS and VLBI data for consistent estimation of Earth Orientation Parameters
Authors: Lengert Lisa , Hellmers Hendrik , Flohrer Claudia , Thaller Daniela , Kehm Alexander
Published: March 2020

We present the current activities of the Federal Agency for Cartography and Geodesy (BKG) towards a combined processing of VLBI and GNSS data.  The main goal of the combined analyses of the two different space-geodetic techniques is the improvement of the consistency between the techniques through common parameters, as Earth Orientation Parameters (EOPs), but also station coordinates and tropospheric parameters through local ties and atmospheric ties, respectively.

The combination of GNSS data with VLBI 24-hour sessions and VLBI Intensive sessions is studied in detail w.r.t. EOPs to exploit he combination benefit to its maximum extend. We analyse the impact of the combination on the technique-specific parameters (e.g. dUT1), but also on common parameters (e.g. LOD, polar motion, station coordinates). When using GNSS data in combination with VLBI Intensive sessions, we can demonstrate an accuracy improvement of the dUT1 time series.

We also study the combination of troposphere parameters, focusing first on the validation of the technique-specific troposphere parameters at VLBI-GNSS co-located sites and on the modelling of the corresponding atmospheric ties.

BKGs primary interest is the combination of GNSS and VLBI data on the observation level. However, the current combination efforts are based on the normal equation level using technique-specific SINEX files as a starting point.
National scale climate change impact assessment – investigating long-term variations in the climate change signal for groundwater levels across geologies and aquifers
Authors: Karlsson Ida Bjørnholt , Eisenbruchner Luc Taliesin , Kidmose Jacob , Højberg Anker Lajer
Published: March 2020

The effect of climate change on groundwater system is still not extensively understood. Studies often focuses on changes in recharge to the groundwater system but rarely investigate the resulting impacts on hydraulic head levels especially the spatial distribution of the change across larger domains.

Only few countries in the world have access to a detailed national hydrological model, and fewer still have done nationwide climate change assessments. This study applies a combination of the newest updated national hydrological model for the entire Denmark (the DK-model 2019, http://dk.vandmodel.dk/in-english/) and 20 climate model projections from the Euro-Cordex project (Jacob et al., 2014) for the RCP4.5 and the RCP8.5 emission scenario (4 and 16 runs respectively). The climate dataset are bias-corrected for the Danish area using double Gamma distribution-based scaling for temperature and precipitation (Pasten-Zapata et al., 2019).

This large dataset is used to evaluate the distribution of the magnitude and direction of changes with special focus on the phreatic surface and the main water-bearing groundwater layers for drinking water consumption in Denmark. The spatial variations in the near-surface impact signal across the entire country is also analyzed, as different Quaternary geology is represented from sandy layers in the west to moraine clay tills in the east and marine sand and clay to the north. The climate dataset is a successive time series from 1970ties to the end of the century and thus also enables an analysis of long-term changes in the state of the groundwater system and aquifers. 

 

 

Jacob, D., Petersen, J., Eggert, B., Alias, A., Christensen, O. B., Bouwer, L. M., Braun, A., Colette, A., Déqué, M., Georgievski, G., Georgopoulou, E., Gobiet, A., Menut, L., Nikulin, G., Haensler, A., Hempelmann, N., Jones, C., Keuler, K., Kovats, S., Kröner, N., Kotlarski, S., Kriegsmann, A., Martin, E., van Meijgaard, E., Moseley, C., Pfeifer, S., Preuschmann, S., Radermacher, C., Radtke, K., Rechid, D., Rounsevell, M., Samuelsson, P., Somot, S., Soussana, J.-F., Teichmann, C., Valentini, R., Vautard, R., Weber, B., and Yiou, P.: EURO-CORDEX: new high-resolution climate change projections for European impact research, Regional Environmental Change, 14, 563-578, 10.1007/s10113-013-0499-2, 2014.

Pasten-Zapata, E., Sonnenborg, T. O., and Refsgaard, J. C.: Climate change: Sources of uncertainty in precipitation and temperature projections for Denmark, Geological Survey of Denmark and Greenland Bulletin 43, e2019430102-2019430101-e2019430102-2019430106, https://doi.org/10.34194/GEUSB-201943-01-02 2019.

 
Integration of bedrock, seismic tomographic and plate kinematic constraints to test models of the India-Asia collision
Authors: Parsons Andrew , Hosseini Kasra , Palin Richard , Sigloch Karin
Published: March 2020

The India-Asia collision is one of the most well-studied orogenic events on Earth; it recorded the terminal stages of the central Tethys ocean basins and offers invaluable insight into the geological processes associated with continental collision. In this study, we integrate bedrock datasets, observations of subducted slabs in the mantle, and plate kinematic constraints, to constrain models for the India-Asia collision and the central Tethys oceans.

Previously proposed models for the India-Asia collision differ in terms of subduction zone configurations and paleogeographic reconstructions of Greater India, which represents to northern passive margin of India prior to collision. Five distinct subduction zone configurations have been proposed previously, which differ in the number of active trenches (one or two trenches) in the central Neotethys Ocean and differ in the respective timing, duration, location and migration of those trenches. Three distinct paleogeographic reconstructions of Greater India have been proposed previously, which differ in size and structure. Here, we consider the validity of these subduction zone configurations and Greater India reconstructions with respect to the bedrock record, plate kinematics and the deep mantle structure of subducted slabs beneath the Indian hemisphere.

Following the assumption that slabs sink vertically through the mantle, the positions and geometries of subducted slabs determined from seismic tomography constrain the locations and kinematics of paleo-subduction zones. Integrating this with bedrock constraints allows us to constrain post-Triassic subduction zone configurations for the central Tethys oceans. Our analysis demonstrates that the Neotethys Ocean was consumed by at least two subduction zones since the Jurassic. At the onset of the India-Asia collision at 59±1 Ma, one subduction zone was active along the southern Asian continental margin at ~20°N. At that time, a second may have been active at subequatorial latitudes, but support for this from a bedrock perspective is lacking. This subduction zone configuration allows for three reconstructions for Greater India: The (1) minimum-area; (2) enlarged-area; and (3) Greater India Basin reconstructions. We integrate these reconstructions and subduction zone configurations in a plate kinematic framework to test their validity for the India-Asia collision.

Our findings show that no single model is entirely satisfactory and each invokes assumptions that challenge accepted concepts. These include our understanding of suture zones, subduction-erosion processes, and the limits of continental subduction. We explore these challenges and their implications for our understanding of the India-Asia collision and continental collisions in general.
Flood exposure and vulnerability estimation methods for residential and commercial assets in Europe
Authors: Paprotny Dominik , Kreibich Heidi , Morales-Nápoles Oswaldo , Wagenaar Dennis , Castellarin Attilio , Carisi Francesca , Bertin Xavier , Terefenko Paweł , Merz Bruno , Schröter Kai
Published: March 2020

Floods affect many types of tangible assets in Europe. Here, we present novel methods of estimating exposure and vulnerability of four important categories of assets: (1) residential buildings, (2) household contents, (3) non-residential buildings, (4) machinery and equipment. One set of models was developed for “residential” assets (1+2) and another one for “commercial” assets (3+4) within the activities of EIT Climate-KIC “SaferPLACES” project. All methods are applicable within Europe using only openly-available datasets at the level of individual buildings. Residential exposure is calculated through combination of estimated useful flood space of buildings and average national replacement costs of buildings and household contents. We devised a method for estimating building height using OpenStreetMap and pan-European raster datasets and transforming it into floor space area. Combining economic and demographic data, we calculated replacement costs of residential assets per m2 of floor space in 30 European countries, covering years 2000–2017. Regarding commercial assets, we created a method to disaggregate economic statistics to obtain detailed building-level estimates of replacement costs of non-residential buildings and machinery/equipment. Finally, we developed two Bayesian Network-based, probabilistic, multivariate models to estimate relative losses to residential and commercial assets. Those combine post-disaster survey data from Germany with information on flood hazard and vulnerability; data from events in the Netherlands and Italy are also used in the residential damage model. The exposure and damage models were tested for a case study of the 2010 coastal flood in France, which is a challenge especially for the damage models built on the basis of fluvial and pluvial floods. Using water depths from hydrodynamic modelling of the event, we found that the models underestimated both residential and commercial losses in the two French departments most affected by the 2010 event, but shown a very close alignment for average losses recorded in the whole affected area. Good performance of the models was achieved in all investigated subcategories (residential buildings’ structure, household contents, agricultural establishments, companies in services & industry). Our models were compared with alternative damage models and exposure estimates, showing the best accuracy in most aspects analyzed.
Reducing uncertainty in emission estimates using perturbed emissions ensembles and novel observations: A focus on Beijing
Authors: Yuan Le , Carruthers David , Hood Christina , Jones Roderic L. , Popoola Olalekan A.M. , Stocker Jenny , Archibald Alexander T.
Published: March 2020

The time lag between the occurrence of emissions and the compilation of an inventory is inevitable. When an emissions inventory is used to simulate air quality, uncertainties in the emissions are propagated into uncertainties in the modelled pollutant concentrations. Such uncertainties can be particularly high in regions undergoing rapid emission changes. Beijing, for instance, has implemented a series of pollution control measures over the past several years and various studies have confirmed significant decreases in the emissions of pollutants such as CO and NOX. Hence, it is crucial to quantify and constrain the uncertainties in existing emission estimates for this region.

We sample the uncertainties in an emissions inventory for Beijing using a high-resolution advanced Gaussian dispersion model with perturbed emissions ensembles (PEEs), and constrain these uncertainties using a comprehensive set of in situ observations, including vertically resolved measurements made from a tower in central Beijing using low-cost sensors. We first construct a PEE by varying key emission parameters including source sectors, vertical and diurnal profiles within their uncertainty ranges estimated through expert elicitation. By removing the baseline contribution to the concentrations, we are able to evaluate the performance of the PEE in simulating the local signal. Based on knowledge gained from the initial PEE, we design a second PEE with optimised uncertainty ranges with which we constrain the uncertainties in the base emission estimates.

Our study shows the applicability of perturbed emissions ensembles and high-resolution, three-dimensional observations in systematically sampling and constraining emission uncertainties. This method has wide implications for air quality modelling, particularly in regions with rapid emission changes or for studies in which emissions inventories are out-dated.
Declining silica availability – a challenge in the North Atlantic region?
Authors: Makareviciute-Fichtner Kriste , Matthiessen Birte , Lotze Heike K. , Sommer Ulrich
Published: March 2020

Understanding how changes in limiting nutrient availability affect life in the oceans requires interdisciplinary efforts. Here we illustrate this with an example of silicon, one of the most common elements on land which bioavailable form, silicic acid (Si(OH)4), is a limiting nutrient for silicifying primary producers, such as diatoms.

 Silicic acid concentrations in the pelagic polar and subpolar North Atlantic have declined by 1-2 μM during spring pre-bloom conditions over the past 25 years. Many coastal areas of the North Atlantic region also face decreased relative availability of silicon due to increased riverine supply of nitrogen and phosphorus and stable or declining loads of silicon. Both declining silicic acid concentrations and declining silicon to nitrogen (Si:N) ratios limit the growth of diatoms, which are major primary producers contributing up to a quarter of global primary production.

To assess the effects of declining silicon availability on phytoplankton communities we conducted a mesocosm experiment manipulating Si:N ratios and copepod grazing pressure on phytoplankton communities from the Baltic Sea. Declining Si:N ratio affected not only diatom abundance and relative biomass but also their species composition and overall plankton diversity. Our results illustrate the importance of silicon in structuring community composition at the base of temperate marine food webs. Changes in silicic acid concentrations and Si:N ratios, therefore, may have far-reaching consequences on oceanic primary production and planktonic food webs.

The decline in silicon concentrations in polar and subpolar North Atlantic waters is attributed to natural multi-decadal variability but is likely amplified by reduced ocean mixing due to increased water temperatures, illustrating the need of international efforts to curb global climate change. The decline in Si:N ratios in coastal oceans also highlights the need for further reduction of nutrient pollution and improved river basin management. This may require interdisciplinary and international approaches to manage anthropogenic perturbations of the silicon cycle.
The North Atlantic Oscillation and related topics
Authors: Greatbatch Richard
Published: March 2020

We start with the severe European winter of 1962/63, a winter when the North Atlantic Oscillation (NAO) index was strongly negative with persistent easterly wind anomalies across northern Europe and the British Isles. We then note that the NAO is a manifestation of synoptic Rossby wave breaking. The positive feedback with which synoptic eddies act to maintain the atmospheric jet stream against friction turns out to also be the mechanism by which the equatorial deep jets in the ocean are maintained against dissipation. We were fortunate to be able to demonstrate this in both a simple model set-up that supports deep jets and directly from mooring data on, and on either side of, the equator at 23 W in the Atlantic Ocean. The deep jets offer some potential for prediction over the neighbouring African continent on interannual time scales. This then leads to a brief discussion of the importance of the tropics for prediction on both seasonal and decadal time scales and longer, linking back to the winter of 1962/63.  The models we use for prediction not only contain surprisingly large biases but also require the parameterization of unresolved processes and some brief discussion will be given on the representation of mesoscale eddies in ocean models, such as are used in prediction systems and for making future climate projections.

 

 
Estimation of wave-induced contribution to Sentinel-1 Doppler shift observations
Authors: Moiseev Artem , Johnsen Harald , Johannessen Johnny
Published: March 2020

The Doppler Centroid Anomaly (DCA) registered by microwave Synthetic Aperture Radar (SAR) contains information about ocean surface motion in the radar line-of-sight direction. The recorded signal is associated with the motion induced by the total wavefield (i.e., both wind waves and swell) and underlying ocean surface currents. Hence, accurate estimates of the wave-induced contribution to the observed DCA is required in order to obtain reliable information about underlying ocean surface current. In this study, we develop an empirical geophysical model function for the estimation of the wave-induced DCA. The study is based on two months of Sentinel-1 SAR Wave mode (WV) DCA observations collocated with wind field at 10m height from the ECMWF model and sea state information from the WAVEWATCH III model.

Analysis of two months of observations acquired over land showed that thanks to the novel Sentinel-1 DCA calibration, the uncertainty in the data does not exceed 3Hz (corresponding to a radial velocity of 0.21/014 m/s in the near/far range. The relationship between the DCA and the near-surface wind is in agreement with previously reported findings under the assumption of fully developed seas; the DCA is about 24% of the range wind speed at 23° incidence angle and decreasing (up to 50%) with increasing incidence angle from 23° to 36°. However, the difference between upwind (i.e., the wind blows towards antenna) and downwind (i.e., wind blows away from the antenna) configurations is inconsistent from study to study. Reliable information about the wave field indeed helps to describe the spread in the DCA, especially at low and moderate wind speeds, and when the ocean surface is dominated by the remotely generated swell.

The CDOP model is used as a baseline for estimating the wind-wave-induced Doppler shift. Retraining of the CDOP model for the Sentinel-1 SAR observations (CDOP-S) yielded a significantly better fit. Then, we extended the GMF with parameters of the wavefield (significant wave height, mean wave period and direction) in the moment of SAR acquisition. Combining information about near-surface wind and ocean surface wave fields also considerably improves the accuracy of the wave-induced Doppler shift estimates. In turn,  the accuracy of the ocean surface current retrievals are improved as demonstrated by the promising agreement with the near-surface ocean surface current climatology based on multiyear drifter observations.
Seaward Dipping Reflectors Sequences (SDRs) mapping in the field of the Mendeleev Rise
Authors: Rodina Elizaveta , Nikishin Anatoly , Startseva Ksenia , Petrov Eugene
Published: March 2020

The report focuses on the strata of the Mendeleev Rise and adjacent Podvodnikov Basin, Makarov Basin, Toll Basin, and North Chukchi Basin together with Lomonosov Ridge and Chukchi Plateau. Eleven 2-D seismic profiles with a total length of 7540 km were interpreted. The uplifts within the study area are represented by asymmetric raised blocks of the crust with strongly rugged by half-graben structures. We found semi-continuous, from moderate to bright high-amplitude gently dipping reflectors similar to SDRs inside some half-grabens. The SDRs complexes distribute only in half-grabens. A few wedges with several kilometers thick can be distinguished here. The lower boundary of SDRs does not clearly trace. The relationship with underlying complexes is uncertain.  SDRs top is bright enough and interpreted as an angular unconformity, that is progressively onlapped by overlying sediments. Top of SDRs probably coincides with rift-postrift boundary age of 110-100 Ma.  We traced the distribution and direction of SDRs and made a map. SDRs dip from the central axis of Mendeleev Ridge in opposite directions – toward to Toll and Podvodnikov basins. In the central part of Podvodnikov and Toll basins are recognized small raised blocks of continental crust to which anti-directional SDRs converge. The nature of this rises can be explained by tectonic uplift. Thus, SDRs complexes dip symmetrically in two directions from the Mendeleev Rise. Two-directional SDRs also occur in conjugate Podvodnikov and Toll basins. They dip from the Mendeleev Rise and from the Lomonosov Terrace and the Chukchi Plateau, respectively. The SDRs occur on the hyperextension continental crust complex and accompany magmatism on volcanic passive margin (VPM). We propose that the Mendeleev Rise was formed as two-directional VPM, and the Lomonosov Terrace and the Chukchi Plateau also was formed as one-directional VPM. The Mendeleev Rise was formed simultaneously with Podvodnikov, Toll and North Chukchi basins ca. 125-100 Ma because of extensional tectonics. We also assume that the Makarov Basin (with obvious half-graben structures) could form simultaneously with the Nautilus Basin. This work was supported by RFBR grants (18-05-70011 and 18-05-00495).
Assessment of different worst-case flood scenarios for Planinsko Polje (Slovenia)
Authors: Mayaud Cyril , Gabrovšek Franci , Blatnik Matej , Kogovšek Blaž , Petrič Metka , Ravbar Nataša
Published: March 2020

Planinsko Polje is a typical example of structural polje located in South Slovenia that encounters regular flooding. The floods can occur several time per year and create a more than 10 km2 large temporary lake. Even if the polje surroundings are densely populated, local people have known since centuries the average level reached by the majority of the floods and avoided constructing below it. However, the occurrence of severe events with maximum water levels far above common values is still possible. While such floods are unusual, they can last for months and drastically affect the life in the polje vicinity. As recent climatic projections expect an increase of extreme meteorological events in a near future, a resulting increase of severe floods in Planinsko Polje might be foreseen. This work aims to investigate the circumstances under which extreme flooding is occurring in Planinsko Polje. The method combines an analysis of historical flood records with a detailed description of five particular high-water events that happened during the last ten years. Then, different worst-case flood scenarios are proposed and tested with a discretized numerical model. The significance of maximum water levels and flood duration arising from modelling results is discussed in light with historical records of extreme floods. Results show that very-high flooding in Planinsko Polje is the consequence of a simultaneous reduction of the ponor drainage capacity with a combination of extreme meteorological events occurring within the polje recharge areas, while the aquifer downstream is already saturated with water. The method has practical applications for people living near Planinsko Polje and can be generalized to other poljes around the world.
Large Eddy Simulation Coupling Model For Small-scale Air-sea Interaction
Authors: Sun Danyi , Li Shuang
Published: March 2020

Atmosphere and ocean are two important factors that affect the earth's climate system, and their interaction is an important topic in the study. In view of the lack of turbulence scale analysis in the traditional large-scale air-sea coupling model, this paper uses the Parallelized Large-Eddy Simulation Model (PALM) to explore the effect of Langmuir circulation on air-sea flux and turbulent kinetic energy budget at a small scale, and conducts air-sea coupled simulation for atmospheric boundary layer (ABL) and ocean mixed layer (OML). The results show that the distribution of air-sea flux near the surface is greatly influenced by the Langmuir circulation, thus strengthening the ocean mixing. The pressure term in the turbulent kinetic energy budget of the ocean is greatly affected by the Langmuir circulation near the sea surface and weakens rapidly as the depth deepens. This study shows the application of the small-scale air-sea coupling model in the study of air-sea flux, which has certain significance for the study of small-scale air-sea interaction.
Evaluation of the impact of extreme storm surge and rainfall in coastal areas
Authors: Qiang Yejia , Zhang Limin
Published: March 2020

Under global warming, extreme meteorological events may increase in some regions in terms of both frequency and intensity in the future. Low-lying coastal areas may face the threat both from intensive rainfall and high sea level caused by sea level rise and enhanced storm surge. The Pearl River Delta (PRD) is one of the economic centers of China and is very densely populated. However, PRD is one of the most storm surge-exposed and flood-exposed urban areas in the world. This paper aims to assess the possible impacts of extreme sea level and rainfall on the costal urban areas in PRD. Frequency analysis on historical data of storm surge level and rainfall intensity is conducted, and several scenarios of combination of different magnitudes of the two meteorological events are designed. The trend of observed local sea level and possible land subsidence are also considered. The scenarios are used as inputs for a flood routing model to evaluate the combined impacts of the two meteorological events. Flood maps are produced for each scenario and the infrastructures potentially affected such as buildings and roads can be identified. The results can help identify critical areas prone to hazards under extreme cases and are meaningful for designing hazard prevention measurements.
Direct temporal cascade of temperature variance in eddy-permitting simulations of multidecadal variability
Authors: Hochet Antoine , Huck Thierry , Arzel Olivier , Sevellec Florian , Colin de Verdiere Alain , Mazloff Matthew , Cornuelle Bruce
Published: March 2020

The North Atlantic is characterized by basin-scale multidecadal fluctuations of the sea surface temperature with periods ranging from 20 to 70 years.
One candidate for such a variability is a large-scale baroclinic instability of the North Atlantic Current. Because of the long time scales involved, most of the studies devoted to this problem are based on low resolution numerical models leaving aside the effect of explicit meso-scale eddies.   
How high-frequency motions associated with the meso-scale eddy field affect the basin-scale low-frequency variabiliy is the central question of this study.

This issue is addressed using an idealized configuration of an Ocean General Circulation Model at eddy-permitting resolution (20 km). A new diagnostic allowing the calculation of nonlinear fluxes of temperature variance in frequency space is presented. Using this diagnostic, we show that the primary effect of meso-scale eddies is to damp low frequency  temperature variance and to transfer it to high frequencies.
Lithosphere thermo-chemical heterogeneity in the European-North Atlantic region, Greenland and Anatolia
Authors: Artemieva Irina , Shulgin Alexey
Published: March 2020

We present a new model, EUNA-rho (Shulgin and Artemieva, 2019, JGR), for the density structure of the European and the North Atlantics upper mantle based on 3D tesseroid gravity modeling and a new regional model for the lithosphere thickness in Europe, Greenland, the adjacent off-shore regions (Artemieva, 2019ab, ESR), and Anatolia (Artemieva and Shulgin, 2019, Tectonics). On continent, there is no clear difference in lithosphere mantle (LM) density between the cratonic and Phanerozoic Europe, yet a ca. 300 km wide zone of a high-density LM along the Trans-European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low density mantle, while the correlation between LM density and the depth of sedimentary basins indicates an important role of eclogitization in basin subsidence, with the presence of 10-20% of eclogite in LM beneath the super-deep platform basins and the East Barents shelf. The Barents Sea has a sharp transition in lithosphere thickness from 120-150 km in the west to 175-230 km in the eastern Barents. Highly heterogeneous lithosphere structure of Anatolia is explained by the interplay of subduction systems of different ages. The block with 150 km thick lithosphere in the North Atlantics east of the Aegir paleo-spreading may represent a continental terrane. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) bathymetry, heat flow and mantle density follows half-space cooling model with significant deviations at volcanic provinces. Strong low-density LM anomalies (<-3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100-150o C at the Azores and can be detected seismically, while a <50o C anomaly around Iceland is at the limit of seismic resolution.

References:

Artemieva I.M., 2019. The lithosphere structure of the European continent from thermal isostasy. Earth-Science Reviews, 188, 454-468.     

Artemieva I.M., 2019. Lithosphere thermal thickness and geothermal heat flux in Greenland from a new thermal isostasy method. Earth-Science Reviews, 188, 469-481.

Shulgin A. and Artemieva I.M., 2019. Thermochemical heterogeneity and density of continental and oceanic upper mantle in the European‐North Atlantic region. Journal of Geophysical Research: Solid Earth, 124, 1-33, doi: 10.1029/2018JB017025 (open access)       

Artemieva I.M. and Shulgin A., 2019. Geodynamics of Anatolia: Lithosphere thermal structure and thickness. Tectonics, 38, 1-23, doi: 10.1029/2019TC005594
Implementation of runoff attenuation features into a landscape evolution model for the assessment of the impact on catchment sediment dynamics
Authors: Pearson Eleanor , Carrivick Jonathan , Lamb Rob
Published: March 2020

Runoff attenuation features such as bunds and leaky barriers are increasingly incorporated into catchment flood management schemes. However, with any structure resulting in a barrier to flow, sediment dynamics are also affected, which will in turn affect the feature’s hydraulic effectiveness over time. The geomorphological impact of these features is often overlooked. This work looks at using the CAESAR-Lisflood landscape evolution model to assess how to implement runoff attenuation features into a catchment and evaluate their corresponding impact on sediment dynamics and subsequent change to water storage efficacy. The simulations were based on a small catchment, situated south of the Yorkshire Dales, UK, where the land is primarily used for grazing livestock. Features were implemented through the editing of the underlying topography allowing features to be fully erodible and scenarios were created based on feature shape, size and quantity. Of the features implemented, there was no unified response to the flood event simulated. Generally, many of the features themselves were affected by erosion, reducing their ability to hold water over time. Fewer features experienced deposition upstream compared to those experiencing erosion, which may suggest scour as opposed to sedimentation as a management issue that would need to be monitored. Nonetheless, the model scenarios run permitted an optimal design and layout of runoff attenuation features within the catchment to be established.
Influence of environmental parameters on bacterial lipids in soils from the French Alps: implications for paleo-reconstructions
Authors: Véquaud Pierre , Derenne Sylvie , Collin Sylvie , Anquetil Christelle , Poulenard Jérôme , Sabatier Pierre , Huguet Arnaud
Published: March 2020

Microorganisms can modify the composition of their lipid membrane in response to variations in environmental parameters. This is the case for bacterial lipids such as glycerol dialkyl tetraethers (GDGT) and 3-hydroxy fatty acids (3-OH FAs), both used for temperature and pH reconstructions in terrestrial paleoenvironmental studies. However, a major concern with these proxies is that their structure may be influenced by other environmental parameters than temperature or pH. The present study aimed at identifying and quantifying the influence of environmental parameters such as soil moisture, vegetation types and soil types on bacterial GDGTs and 3-OH FAs. These lipids were analyzed in 49 soil samples collected between 200 m and 3,000 m altitude in the French Alps. The soils cover a wide range of temperature (0 °C to 15 °C) and pH (3 to 8) and are representative of the diversity of soils and vegetation encountered along the investigated altitudinal transects. Using this new well-documented and unique dataset, the GDGT-pH correlation was confirmed, but the one between 3-OH FAs and pH was lower than in previous studies. For the temperature, correlations were lower than in previous studies for the GDGTs and absent for the 3-OH FAs. These observations could be explained thanks to different statistical analyses. Redundancy analysis (RDA) showed that pH is the main driver of the variability of 3-OH FAs and GDGTs, explaining 20.5 % and 56 % of the distribution of these bacterial lipids, respectively, followed by the altitude (8 % influence on the distribution of 3-OH FAs, and 11 % on GDGTs) and granulometry (5 % impact on 3-OH FAs and 7.5 % on GDGTs). Taken together, these results highlight the major influence of the vegetation cover and soil types on the distribution of bacterial lipids. Indeed, we quantified and explained for the first time the impact of the different environmental factors (temperature, vegetation, soil type…) on the distribution of bacterial lipids. This novel comprehension of the impacts of environmental parameters will allow to refine the use of proxies based on these compounds. These results pave the way for new types of applications of GDGTs and 3-OH FAs as environmental proxies in paleosoils, peat or lacustrine sediments.
Hydrometeor classification in convective clouds using cloud profiler data
Authors: Minářová Jana , Sokol Zbyněk
Published: March 2020

In this contribution, we investigate hydrometeors and their distribution in thunderclouds. We classify 5 kinds of hydrometeors using data of a Ka-band cloud profiler (35 GHz) situated at the weather station Milešovka in Central Europe. The classification of hydrometeors is based on calculated vertical air velocity, terminal velocity of a target, minimum and maximum terminal velocity of hydrometeor classes, and Linear Depolarization Ratio within three temperature intervals. We performed the classification for convective events that were observed at the station in 2018 and 2019 and were related to lightning in the vicinity of the station.

Results suggest that there is a link between lightning flashes observed close to the weather station (based on EUCLID data) and the presence of graupel, ice, snow, and hail. These are the hydrometeors (graupel and ice in particular) that are considered to play major role in thundercloud electrification by the collision of hydrometeors.