bluuebunny/crossref_metadata_2025 huggingface dataset:
Compiling and correlating paleostress fields across Central Europe - A paleostress chart for northern Bavaria and adjacent areas
Authors: Duschl Florian , Stephan Tobias , Köhler Saskia , Köhn Daniel , Stollhofen Harald , Drews Michael
Published: March 2021

Detailed knowledge on the temporal and spatial distribution of faults and fractures not only reveals the geodynamic and tectonic evolution of the lithosphere. It is also of increasing importance with regard to economic, social, and environmental challenges such as nuclear waste disposal, gas storage, geothermal energy, natural hazards, and mineral resource exploration. In this context reliable data on both timing and kinematics of deformation and their regional impact on faulting and fracture formation provide crucial information to evaluate exploration, storage, and production risks, which in turn stresses the need for comprehensive data on paleostress fields and their influence on deformation, fault reactivation, fluid activity, and hydrothermal mineralization.

In this study we present a first comprehensive approach to compile and visualize information on the crustal paleostress field of Central Europe with a focus on northern Bavaria and adjacent areas. The compilation includes published structural data from kinematic paleostress analyses (e.g. fault-slip analysis, tectonic stylolites) and geo- and thermochronological ages of fracture mineralization and fault activity, respectively. The present compilation comprises structural records from more than 40 studies and age information from more than 100 geo-thermochronological studies. All structural data are categorized according to its tectonic stress regime and quality-ranked for reliability and comparability. The consequent linkage of structural data with thermochronological data wherever possible allows to correlate local paleostress fields and deformation patterns with regional to global tectonic events. As one result, the “Paleostress Chart for Northern Bavaria and adjacent Areas” visualizes the temporal and spatial evolution of several regions in Central Europe together with known tectonic phases, sedimentary unconformities and the plate kinematic framework since the Carboniferous.

This compilation may therefore help to better understand the timing and the spatio-temporal evolution of crustal stress patterns for tectonic events across Central Europe in the context of plate tectonics. 

We aim to supplement and improve existing paleostress models on both, regional, and temporal scale by compiling published and original data. In the long term the database is intended as a continuing compilation where data from all across Central Europe are supposed to be included and refined subsequently.
Analysis of GNSS data along the Southern Gas Corridor and estimate of the expected slowly-cumulating tectonic displacements
Authors: Rossi Giuliana , Caputo Riccardo , Zuliani David , Fabris Paolo , Maggini Massimiliano , Karvelis Panagiotis
Published: March 2021

Coseismic surface displacements, soil liquefaction effects, and induced landslides are among the most critical issues to be accounted for evaluating the exposure and vulnerability of pipelines. However, tectonic plates and crustal blocks are in an almost continuous relative movement, most pronounced in the narrow zones between tectonic plates, where we observe differential velocities from a few mm to some cm per year. Hence, even without the occurrence of strong earthquakes, a pipeline crossing active tectonic plate boundaries must cope during its lifetime, with remarkable differential motions along its length, due to the interseismic elastic strain-accumulation within the upper crust. Such movements, leading to permanent ground deformation, can distress the pipe and cause operation interruptions, while the anchor points can result in local stress concentrations.

Here, we analyze the Southern Gas Corridor’s final part, a route highlighted in the European Energy Security and Energy Union Strategies. This route, which will be occupied by the TransAdriatic pipeline, crosses one of the world’s most seismically active zones. Our study aims to identify areas where critical differential motions could be expected along the route over the nominal 50-years pipeline-lifespan. We analyzed the available GNSS data and interpolated the sparsely available velocity vectors to have regular information along the pipeline path in two ways. In the first, we considered the region as a continuum; in the second, we applied an original blocky approach. We subdivided the path into segments, characterized by a relatively homogenous deformational behavior, or a specific tectonic setting, independently upon the neighboring ones. We compared the results of the two methods with the input observation. We calculated the maximum displacement that would cumulate in the next 50 years and the differential displacements that could cause possible critical bending to the pipeline structure. The approach followed in this research could be applied to other infrastructures to identify the segments prone to localized deformation because of interseismic tectonic loading.

The work was done within the Trans Adriatic Pipeline Seismological Investigation RfP Seismic Hazard Assessment Evaluation for E.ON New Build & Technology GmbH. We thank Dario Slejko and the other project partners for valuable information, data, advice, and fruitful discussions. For our GIS-based strain velocity system, we used Quantum GIS (QGIS), a user-friendly Open Source Geographic Information System (GIS) licensed under the GNU General Public License (https://hub.qgis.org/). For the interpolation, we used the function TriScatteredInterp from MATLAB® library (MATLAB R2011a).
Neanderthal landscapes and subsistence strategies during late Quaternary glacial-interglacial periods: insights from the avian assemblages of Grotta del Cavallo (Apulia, Southern Italy)
Authors: Carrera Lisa , Scarponi Daniele , Martini Fabio , Sarti Lucia , Pavia Marco
Published: March 2021

Grotta del Cavallo, a well-known Paleolithic site in Southern Italy (Nardò, Apulia), preserves one of the most important Italian Middle Paleolithic sequences. Its stratigraphic succession records the presence of Neanderthals from Marine Isotope Stage (MIS) 7 to 3, providing substantial insights on their lifeways. Here we present the taxonomic and taphonomic analysis of the bird assemblages associated to Neanderthal occupation. The rich avifaunal assemblages allowed paleoenvironmental and paleoclimatic reconstructions, noticeably improving the reconstruction of the landscape that was exploited by Neanderthals throughout the last glacial-interglacial cycles. Based on the bird taxa identified in the assemblages, Grotta del Cavallo was mainly surrounded by extensive grasslands and shrublands, with scattered open woodland and rocky outcrops, during MIS 7, 6 and 3. The coastal plain, that is currently underwater due to Holocene relative sea-level rise, hosted wetlands in the cooler periods, when it was exposed. In the cool-temperate climatic phase attributed to MIS 3, bird taxa of water and wet environments proportionally increased, as well as coverage-based rarefied richness values. This is possibly due to the expansion of wetland areas, linked to more humid conditions, or to the shorter distance of the wetland settings from the cave, compared to MIS 6 (glacial period). A consequent higher heterogeneity of the landscape is retained to drive the increased richness. The sampling effort allowed to retrieve bird taxa that provided significant paleoclimatic insights, such as Branta leucopsis, an arctic breeder, and other species currently spread at higher altitudes, that reinforce previously obtained geochemical derived inference of climate conditions cooler than the present ones. The bird assemblages also provided the first occurrence ever of Larus genei, the first Italian occurrence of Emberiza calandra, the oldest Italian occurrence of Podiceps nigricollis, and the occurrence of Sylvia communis (a species rarely retrieved in the fossil record). Ordination analyses of the bird dataset detected the drivers of taphonomic degradation and the agents responsible for the accumulation of the avian bones: modifications are mainly due to physical sin- and post-depositional processes, whereas accumulation is mainly attributed to short-range physical processes of sediment accumulation, feeding activities of nocturnal raptors and, to a lesser extent, human activities. In detail, traces found on a few bones suggest that Neanderthals introduced some of the birds in the cave with alimentary purposes, providing the earliest Italian evidence of bird exploitation ever.
A new coupled model to shed light on sea-ice--ocean interactions
Authors: Boutin Guillaume , Ólason Einar , Rampal Pierre , Lique Camille , Talandier Claude , Brodeau Laurent
Published: March 2021

Sea ice is a key component of the earth’s climate system as it modulates air-sea interactions in polar regions. These interactions strongly depend on openings in the sea ice cover, which are associated with fine-scale sea ice deformations. Visco-plastic sea ice rheologies used in most numerical models struggle at representing these fine-scale sea ice dynamics without going to very costly horizontal resolutions (~1km). A solution is to use damage propagation sea ice models, which were shown to reproduce well sea ice deformations with little dependency on the mesh resolution. 

Here we present results from the first ocean--sea-ice coupled model using a rheology with damage propagation. The ocean component is the NEMO-OPA model. The sea ice component is neXtSIM, introducing the newly developed Brittle Bingham-Maxwell rheology. Results show that sea ice dynamics are very well represented from large scales (sea ice drift) to small-scales (sea ice deformation). Sea ice properties relevant for climate, i.e volume and area, also show a remarkable match with satellite observations. This coupled framework opens new opportunities to quantify the impact of small-scale sea ice dynamics on ice-ocean interactions.
Seismic structure of the Cheb Basin from high resolution surveying – data quality assessment and first results
Authors: Banasiak Natalia , Bleibinhaus Florian
Published: March 2021

In this study we present data and preliminary results from several shallow high-resolution seismic surveys in the Cheb Basin, CR, a small intracontinental basin in the North-West Bohemian Massif, located at the Western end of the Cenozoic Eger Rift. The area is well known for its intense earthquake activity, with the largest instrumentally recorded magnitude of ML=4.6. Macroseismic reports of local seismicity date back to the early 19th century, with magnitudes possibly above 5. Quaternary volcanoes, CO2-rich moffettes, and the swarm-like occurrence of the earthquakes suggest they are being triggered by crustal fluids. In contrast, most focal mechanisms show a dominant strike-slip component, indicative of tectonics. Investigating the role of fluids in triggering those earthquakes is one of the objectives of an ongoing ICDP program.

We expect high-resolution images of the basin structure to provide additional constraints regarding the importance of tectonic faulting. To that end, we surveyed several up to 3-km-long reflection and refraction profiles in the basin center across the putative Počátky-Plesná Fault, and at its edge, across the basin-bounding Mariánské Lázně Fault. The up to 350-m-thick basin sediments are mostly of Miocene and Quaternary origin, overlying Paleozoic Variscan units and post-Variscan granites. The main reflectors are around 200-400 ms. The data were collected with a 500-m-long split-spread of single geophones at 2 m spacing, and the raw shots are dominated by ground roll. In this presentation, we will show an overview of the field campaigns and present first results.
Predictability of seawater DMS during the North Atlantic Aerosol and Marine Ecosystem Study (NAAMES)
Authors: Bell Thomas , Porter Jack , Wang Wei-Lei , Lawler Michael , Hoyle Faith , Chase Alison , Boss Emmanuel , Karp-Boss Lee , Kramer Sasha , Siegel David , Graff Jason , Behrenfeld Michael , Saltzman Eric
Published: March 2021

Surface ocean dimethylsulfide (DMS) was measured during four shipboard field campaigns conducted during the North Atlantic Aerosol and Marine Ecosystem Study (NAAMES).  Variations in surface seawater DMS are discussed in relation to biological and physical observations. The interplay of biomass and physics influences DMS concentrations at regional/seasonal scales and at smaller spatial and shorter temporal scales. Observations are compared with the best-available climatological predictions of seawater DMS, including output from an empirical algorithm and a neural network model. The input terms common to the algorithm and neural network approaches are biological (chlorophyll) and physical (mixed layer depth, photosynthetically active radiation, seawater temperature). DMS concentrations tend to be under-predicted and the episodic occurrence of higher DMS concentrations is poorly predicted. The choice of climatological seawater DMS product makes a substantial impact on the estimated DMS flux into the North Atlantic atmosphere. These results suggest that additional input terms are needed to improve the predictive capability of current state-of-the-art approaches to estimating seawater DMS.
Enhanced paleo-wildfire occurrences caused by marine organic carbon burial during the Late Devonian Frasnian–Famennian mass extinction
Authors: Lu Man , Lu YueHan , Ikejiri Takehitio , Carroll Richard
Published: March 2021

The Frasnian–Famennian (F–F) boundary is characterized by worldwide depositions of organic-rich strata, a series of marine anoxia events and one of the biggest five mass extinction events of the Phanerozoic. Due to the enhanced burial of organic matter, a coeval positive carbon isotope (δ13C) excursion occurred around the F–F boundary, raising questions about carbon cycle feedbacks during the mass extinction. In this study, we test the hypothesis that enhanced burial organic carbon during the F–F mass extinction led to the rise of paleo-wildfire occurrences. Here, we reconstructed paleo-wildfire changes across the F–F boundary via analyzing fossil charcoal (inertinites) and pyrogenic polycyclic aromatic hydrocarbons (PAHs) from an Upper Devonian Chattanooga Shale in the southern Appalachian Basin. Our data show low abundances of inertinites and pyrogenic PAHs before the F–F transition and an increasing trend during the F–F transition, followed by a sustained enhancement through the entire Famennian interval. The changes in paleo-wildfire proxies suggest a rise of wildfires starting from the F–F transition. Furthermore, we quantified the amount of organic carbon burial required to drive the observed δ13C excursion using a forward box model. The modeling results show an increased carbon burial rate after the onset of the F–F transition and peaking during its termination. The comparison of the carbon burial rate and wildfire proxies indicates that widespread organic carbon burial during the F–F transition might cause elevated atmospheric oxygen levels and hence increased occurrences of wildfires. In addition, chemical index alteration index and plant biomarkers suggest a drying climate initiated during the F–F transition, implying that the enhanced carbon burial probably result in the climate change and amplify the wildfire occurrences.
Comparing traditional geomechanical and remote sensing techniques for rock mass characterization 
Authors: Caccia Angela , Palma Biagio , Parise Mario
Published: March 2021

Analysis of the stability conditions of rock masses starts from detailed geo-structural surveys based on a systematic and quantitative description of the systems of discontinuities. Traditionally, these surveys are performed by implementing the classical geomechanical systems, available in the scientific literature since several decades, through the use of simple tools such as the geological compass to measure dip and dip direction directly on the discontinuity systems, and to fully describe their more significant physical characteristics (length, spacing, roughness, persistence, aperture, filling, termination, etc.). In several cases, this can be difficult because the discontinuities, or even the rock face, cannot be easily accessible. To have a complete survey, very often the involvement of geologists climbers is required, but in many situations this work is not easy to carry out, and in any case it does not cover the whole rock front.

Today, to solve these problems, traditional geomechanical surveying is implemented by innovative remote techniques using, individually or in combination, instruments such as terrestrial laser scanners and unmanned aerial vehicles to build a point cloud.

This latter permits to extract very accurate data on discontinuities for stability analyses, based on areal and non-point observations. In addition, the point cloud allows to map sub-vertical walls in their entirety in much shorter times than traditional surveying.

At this regard, two rock slopes were detected in the Sorrento Peninsula (Campania, southern Italy) with techniques that include traditional mapping, dictated by the guidelines of the International Society for Rock Mechanics, and the remote survey, through laser scanning and drone photogrammetry. The data obtained were processed automatically and manually through the Dips, CloudCompare and Discontinuity Set Extractor softwares.

In the present contribution we highlight the limits and advantages of the main data collection and the processing techniques, and provide an evaluation of the software packages currently available for the analysis and evaluation of discontinuities, in order to obtain a better characterization of the rock mass.
Compound Drought-Flood Events in Fragile Contexts: Examples from the Horn of Africa
Authors: Matano Alessia , Van Loon Anne , de Ruiter Marleen , Koehler Johanna , de Moel Hans , Ward Philip
Published: March 2021

Humanitarian crises often result from a combination of multiple physical and societal processes, rather than independently from a single driver. The combination of processes leads to “compound events”, whose socio-economic impacts could be larger than those expected by analysing each driver individually. In recent years, the Horn of Africa has been increasingly exposed to compound events. Frequent extreme wet and dry conditions often compound with its fragile context characterized by internal ethnic conflicts, unstable governments, and high levels of poverty, resulting in impacts usually larger than anticipated. An improved understanding of the drivers and their interactions can help to reduce future risks associated with compound events.

Here, we conducted a retrospective analysis of the humanitarian crises that occurred in Kenya and Ethiopia in 2017-2018. In this period, a severe drought that occurred over the span of around 18/24 months, was followed by extensive flooding during the 2018 March-May rainy season. The impacts and their related drivers were explored, first through a review of the literature, and then through a survey and semi-structured interviews with several stakeholders from national agencies, civil societies, and NGOs. The approach resulted in a participatory co-creation of causal loop diagrams used as qualitative mental maps of the perceived drivers and interactions. These were then used as a basis for the semi-quantitative analysis of driver-interactions, modelling the impacts of immediate and long-term effects of the compound events.

The analysis disentangles the spatial-temporal feedback of drought and flood events, and their interconnections with societal forces. We found both negative and positive feedback on the food security level of the Kenyan and Ethiopian population. For instance, the flood initially exacerbated food insecurity caused by the long drought, but in the long term, it helped alleviate related water shortages. The results show the importance of taking drought response actions that first do not increase the risk related to subsequent floods (e.g., encouraging the allocation of people in lowland areas), but also that can boost the positive impacts of above-average rainfall on drought effects. Moreover, we investigated potential early warning signs and explored the impacts of several measures, identifying windows of opportunity for interventions.
Dendrochronological potential of the Azorean endemic gymnosperm Juniperus brevifolia (Seub.) Antoine
Authors: C Pavão Diogo , Jevšenak Jernej , Camarinho Ricardo , Rodrigues Armindo , Borges Silva Lurdes , B Elias Rui , Silva Luís
Published: March 2021

Tree-ring interannual pattern variation is crucial in dendrochronology, allowing the identification of possible limiting factors on growth. Thus, trees exposed to sub-tropical or tropical climates without a marked seasonality, may show a low degree of interannual variation, impeding a straightforward dendroclimatological approach. Meanwhile, subtropical regions, and areas in transitional climates such as the Azores archipelago, are widely unexplored in terms of dendroclimatology, providing opportunities to work with endemic trees, including the dominant Azorean tree Juniperus brevifolia (Seub.) Antoine. To evaluate the dendrochronological potential of J. brevifolia, we analyzed wood anatomy and tree-ring patterns, cross-dating capabilities, and correlation with climate parameters. We sampled 48 individual trees from 2 natural populations (São Miguel and Terceira islands) using an increment borer. In addition, a Trephor tool was used to obtain wood microcores for micro-anatomical analysis. Tree-ring widths were measured with CooRecorder (Cybis) and cross-dated with the PAST-5 software (SCIEM). After detrending, master chronologies were built and correlated with aggregated daily temperature and precipitation data using the dendroTools R package. Microcores were prepared following standard protocols to obtain high resolution images. Our results showed the transition from latewood to earlywood marked by thick-walled fibers, . However, there were also unclear ring transitions or partially indistinct ring boundaries and wedging rings, complicating the cross-dating process. Our preliminary climate-growth correlations indicated significant positive correlations with precipitation at the end of the growing season. Our results suggest an acceptable dendrochronological potential for Juniperus brevifolia, which could be further used in distribution modelling or in recent climatic reconstructions, for which more samples will have to be analyzed.
Rapid extreme meteorological events detected by daily regional GRACE solutions
Authors: Ramillien Guillaume , Seoane Lucia , Darrozes José
Published: March 2021

We investigate the possibility to use the Low-Earth Orbiter mission well known as GRACE to detect sudden regional variations of water mass storage caused by heavy precipitation and flooding episodes caused by the passage of tropical hurricanes of categories 4-5 (from day to a week). For this purpose, daily water mass solutions are produced from along-track GRACE geopotential anomalies to catch the signatures of these intense meteorological events. These geopotential variations are derived from accurate inter-satellite K-Band Range Rate (KBRR) measurements made along the 5-second orbits by imposing the total energy conservation to the twin GRACE vehicles. The determination of these surface sources is made over a regional network of juxtaposed triangular tiles of quasi-constant areas, and they are refreshed by a Kalman filtering for integrating progressively daily geopotential observations. These latter data have been previously reduced from known gravitational effects of atmosphere and oceanic masses (including periodic tides) for isolating the continental hydrology contribution. Our estimates of regional hydrological impacts are also compared to the ones obtained by synthesis of daily degree-40 Stokes coefficients provided by ITSG, Graz.
Modern pollen distributions and their relationship with environmental gradient in Southern Morocco
Authors: Tadoumant Sokaina , Bouimetarhan Ilham , Koelling Martin , Baqloul Asmae , Bouchaou Lhoussaine
Published: March 2021

      Terrestrial signals in marine sediment archives are frequently used for paleoclimate reconstructions. A little is known about the origin of terrestrial components such as pollen and spores, organic and inorganic elements in the sedimentary archives. The aims of this study is to investigate the geographic distribution pattern of pollen and spores in southern Morocco in relation to environmental gradients, and different transport mechanisms in order to link temporal variations in marine sediment cores to environmental changes in southern Morocco. Pollen taxa of Argania spinosa, Cichorioideae, Poaceae and Cyperaceae exhibit high percentages and concentrations in the semi-arid Souss Massa basin and the relatively humid Tensift basin accompanied with higher values of Fe/Ca and Ti/Al. Moreover, the simulation between distribution of Olea/Phillyrea and Ti/Al ratio suggests that Olea/Phillyrea are mainly dispersed by wind transport. However, Artemisia and Quercus distributions are limited to the south of High Atlas and the northern Anti Atlas. Chenopodiaceae, Caryophyllaceae , and Amaranthaceae (CCA) show a maximum percentages in littoral sites especially of Souss and Draa basins according to the important production of pollen quantities, the  high values of CCA from north to south of study area are indicated the starts of Saharan-type climate with increasing values of Acacia, Ziziphus, Asphodelus and Tamarix taxa may indicate plants adaptation to droughts, and/or a dominant aeolian transport. The South of Morocco which is known by higher wind inflows and low rainfall during the year occurring as occasional events during the winter, we conclude that pollen are primarily transported by the NE trade winds and occasionally with rivers in the basins.
Long-term mass balance and firn modelling for Abramov glacier, Pamir Alay
Authors: Kronenberg Marlene , Machguth Horst , van Pelt Ward , Hoelzle Martin
Published: March 2021

The application of a coupled energy balance-subsurface model allows studying the mass balance evolution of mountain glaciers and thereby assessing the role of subsurface processes in the accumulation area. Such model simulations are scarce for glaciers in High Mountain Asia where meteorological and glaciological calibration data are poorly available. Uncertainties in mass balance estimates are therefore high and questions regarding changes in accumulation and ablation regimes remain open.

Here, we run a distributed energy balance model coupled to a multi-layer snow model for Abramov glacier (Pamir Alay, 39.60°N 71.55° E) over the time period 1968 to present. A unique set of meteorological and glaciological data measured from 1968-99 is used to forceand calibrate the coupled model. The modelling period is extended to present using gridded precipitation data and recent measurements from an automatic weather station installed in 2012. We use repeated firn profiles from the 1970s and 2018 to evaluate modelled evolution of snow and firn conditions.

Preliminary modelling results show that the mass balance of Abramov glacier has been predominantly negative since 1969. However, also periods with increasing mass balance trends have been found since then. For the period of historical measurements (1968-98), our results suggest an increase of net accumulation in the accumulation area. This result points towards a steepening of the mass balance gradient, which may cause increased dynamics.
Saturn´s Stratospheric Hazes From HST Ultraviolet Imaging
Authors: Sanz Requena José Francisco , Pérez Hoyos Santiago , Sánchez-Lavega Agustín , Melin Henrik , Fletcher Leigh , Irwin Patrick
Published: March 2021

We present a study on Saturn's stratospheric hazes using archived images from the Hubble Space Telescope Advanced Camera for Surveys. These observations were taken from 2005 to 2014, including the Great Storm during the years 2010 and 2011. For our research we used ultraviolet images from the Solar Blind Channel camera equipped with the F115LP and F125LP filters. At these wavelengths, the reflected spectrum is fundamentally Rayleigh-scattered, with substantial contributions from hydrocarbon absorptions and additional scattering by the aerosols in the hazes above the tropopause. The goal of this work is to analyze temporal and latitudinal changes in the characteristics of the stratospheric haze, gases and particles, analyzing the absolute reflectivity and its limb darkening. Such behavior can be reproduced using the empirical Minnaert's law. This provides nadir-viewing reflectivity and limb darkening coefficient as a function of latitude and time. This is a first approach that helps to qualitatively identify the changes occurring in the aerosol layer during this period of time, which include the massive Great White Spot of 2010. In order to quantify such aerosol changes, we use the radiative transfer code and retrieval suite NEMESIS (Non-Linear Optimal Estimator for Multivariat Spectral AnalySIS) to reproduce the observed reflectivity.  Here we will focus on the detected variations of the vertical distribution of the stratospheric particles, their integrated optical thickness and size distribution and will correlate them with the seasonal changes taken place in the atmosphere of the planet.
Causal discovery in climate research: Overview and recent progress
Authors: Runge Jakob , Gerhardus Andreas
Published: March 2021

Discovering causal dependencies from observational time series datasets is a major problem in better understanding the complex dynamical system Earth. Recent methodological advances have addressed major challenges such as high-dimensionality and nonlinearity (PCMCI, Runge et al. Sci. Adv. 2019), as well as instantaneous causal links (PCMCI+, Runge UAI, 2020) and hidden variables (LPCMCI, Gerhardus and Runge, 2020), but many more remain. In this presentation I will give an overview of challenges and methods and present a recent approach, Ensemble-PCMCI, to analyze ensembles of climate time series. An example for this are initialized ensemble forecasts. Since the individual samples can then be created from several time series instead of different time steps from a single time series, such cases allow to relax the assumption of stationarity and hence to analyze whether and how the underlying causal relationships change over time. We compare Ensemble-PCMCI to other methods and discuss preliminary applications.

Runge et al., Detecting and quantifying causal associations in large nonlinear time series datasets, Science Advances eeaau4996 (2019).

Runge, J. Discovering contemporaneous and lagged causal relations in autocorrelated nonlinear time series datasets. Proceedings of the 36th Conference on Uncertainty in Artificial Intelligence, UAI 2020, Toronto, Canada, 2019, AUAI Press, 2020

Gerhardus, A. & Runge, J. High-recall causal discovery for autocorrelated time series with latent confounders. Advances in Neural Information Processing Systems, 2020, 33
Decadal-scale assessment of blue and green water resources in the Brahmani river basin, Odisha
Authors: Swain Sushree Swagatika , Mishra Ashok , Chatterjee Chandranath , Sahoo Bhabagrahi
Published: March 2021

Inherent knowledge of the river basin-scale water balance components is essential for long‐term management of water resources planning and food security at a regional scale. This study explains a combined approach using the Soil and Water Assessment Tool (SWAT) followed by the Sequential Uncertainty Fitting program (SUFI‐2) concept to calibrate and validate the hydrologic models of the Brahmani basin based on observed streamflow at a monthly time‐step. The water balance components in terms of blue water flow (surface runoff, return flow, and lateral flow), green water flow (actual evapotranspiration), and green water storage (soil moisture storage) of the study area are assessed at a decadal scale (1979-88, 1989-98, and 1999-2008). The first 7 years of each decade are considered as calibration period (1979-85, 1989-95, and 1999-05) and the remaining years are the validation period (1986-88, 1996-98, and 2006-08). The results of the initial decade (1979-88) showed that there is a balance between blue water flow, green water flow, and green water storage components. There is an increasing trend in blue water flow and green water flow components in the mid-decade (1989-98). However, there is a fluctuation in green water storage. It is decreasing in mid-decade and increasing towards the end decade (1999-2008). The warm and humid climate of the study area is expected to affect the variation of the above components. The vulnerability of water balance components is crucial for maintaining regional-scale water demand and food security. However, the alarming impacts of climate change could adversely affect the above situation. Water availability component analysis at a decadal scale has not been explored widely in the present study area. This study can help the policy-makers to maintain a balance between water demand from different sectors and availability to avoid water scarcity of a river basin in the future. Further, the developed approach for the analysis of blue and green water can be applied in other arid and semi‐arid regions.
Boreal forest carbon exchange and growth recovery after the summer 2018 drought
Authors: Linderson Maj-Lena , Holst Jutta , Edvardsson Johannes , Heliasz Michal , Klemedtsson Leif , Klosterhalfen Anne , Krasnova Alisa , Linderson Hans , Martínez García Eduardo , Mölder Meelis , Peichl Matthias , Sohar Kristina , Soosaar Kaido , Tung Chen Tzu , Vestin Patrik , Weslien Per , Lindroth Anders
Published: March 2021

In summer 2018, Northern Europe experienced an extreme summer drought in combination with unusually high temperatures, which had a substantial impact on agricultural yields as well as on forest growth conditions in various ways. An earlier study, using ICOS RI (Integrated Carbon Observation Research Infrastructure) stations and other forest ecosystem stations in the Nordic region, shows that the drought dramatically decreased NEP in the southern Scandinavian and Baltic region, almost nullifying the carbon sinks in some of the forests [1]. Such severe conditions during a single year could be expected to influence a forest over following several years. Reduced tree storage of carbohydrates leads to a changed carbon allocation pattern in spring that may affect both the woody growth and pests' resistance. It is thus important to reveal the impact of such climatic events over a more extended period.    

This study aims at assessing the carry-over effects of the extreme weather conditions on the carbon and water fluxes and the forest growth to the years after the event. The analysis is based on measurement from the stations shown to be significantly affected by the drought through reduced carbon fluxes in 2018: the spruce forests Hyltemossa and Skogaryd and the mixed forests Norunda, Svartberget, Soontaga and Rumperöd. The ecosystem carbon and water fluxes will, together with tree-ring width data, be used to assess the carbon and water exchange and growth recovery in the years after the extreme 2018 drought (2019 and 2020) by comparisons to earlier normal years and extreme events.

[1] Lindroth, A., et al. (2020): Effects of drought and meteorological forcing on carbon and water fluxes in Nordic forests during the dry summer of 2018 Phil. Trans. R. Soc. B37520190516 https://doi.org/10.1098/rstb.2019.0516
Stable isotopes of oxygen to characterize a Metalimnetic Oxygen Minimum: insights from a 48 hours field campaign at Rappbode Reservoir, Germany
Authors: Dordoni Marlene , Rinke Karsten , Seewald Michael , Schmidmeier Jakob , Barth Johannes A.C.
Published: March 2021

The appearance of a Metalimnetic Oxygen Minimum (MOM) has been recorded in many natural lakes and reservoirs. However, its isotopic characterization with oxygen and carbon stable isotopes have not yet been fully constrained. The purpose of this work is to apply stable isotopes of carbon and oxygen to characterize photosynthetic and respiratory activities in the Rappbode Reservoir, Germany. Here we present the results of a 48 hours intensive sampling in July 2020. We provide preliminary data of dissolved oxygen (DO) concentration and saturation profiles, together with dissolved inorganic carbon (DIC). This includes data of oxygen (δ18ODO) and carbon (δ13CDIC) stable isotopes with particular focus on the metalimnion. Our profiles identified minor differences from day to day, such as an additional respiration-like peak above the MOM. Samples from within the MOM were characterized by the lowest oxygen content and saturation (7.05 mg L-1 and 75 %, respectively) and the highest δ18ODO (up to +30.1‰). These samples also showed the lowest δ13CDIC values (down to -12.8‰). Surface layers (between 0 and 9 meters) and the deepest water sample (65 meters) did not follow the expected depth profiles for δ18ODO and δ13CDIC. Surface layers were likely influenced by equilibration with the atmosphere that was enhanced by windy conditions. On the other hand, samples from 65 meters depth could have been perturbed by the presence of organic material from sediments. Moreover, oxygen and carbon stable isotopes patterns were able to show that the MOM can migrate within the water column up to 5 meters within 12 hours. These findings offer an interesting basis to establish mass balances of oxygen and carbon turnover in water bodies.
Retrieval of tropospheric BrO columns from TROPOMI and their validation using MAX-DOAS measurements in Ny-Ålesund
Authors: Seo Sora , Richter Andreas , Blechschmidt Anne-M. , Bougoudis Ilias , Wittrock Folkard , Bösch Tim , Burrows John P.
Published: March 2021

Bromine compounds play an important role in atmospheric chemistry with respect to ozone chemistry and the resulting oxidation capacity. Large amounts of reactive bromine can be released by an autocatalytic heterogeneous mechanism called “bromine explosion”, and plumes of enhanced bromine monoxide (BrO) have been observed over polar sea ice regions by satellite measurements in spring. These enhancements of BrO columns result from increases in stratospheric or tropospheric bromine columns or both. As nadir-viewing UV-visible spectrometers have limited vertical resolution, it is not straight-forward to separate total BrO columns into tropospheric and stratospheric partial columns using satellite data.

In this study, an algorithm for tropospheric BrO retrieval from satellite measurements including TROPOMI, which provides much improved spatial resolution, was developed. The retrieval algorithm is based on the Differential Optical Absorption Spectroscopy (DOAS) technique and three different stratospheric correction methods were tested based on: output from a 3D atmospheric chemistry model, a climatology of stratospheric BrO profiles, and an empirical multiple linear regression model to separate the tropospheric partial column from the total column.

Retrieved tropospheric BrO columns from satellite measurements were compared with ground-based MAX-DOAS BrO observations at the NDACC station in Ny-Ålesund. The comparisons between ground-based and satellite measurements of tropospheric BrO show good agreement in both time-series and scatter plots, demonstrating the satellite retrieval algorithm is valid and applicable to study bromine release in the tropospheric layer. In particular, TROPOMI shows improved validation results for short distance collection compared to previous satellite data, which suggests the applicability of high-resolution satellite data on small-scale bromine explosion events observed during the MOSAiC campaign.
Quantifying the spatial and temporal influence of infrastructure on seasonal snow melt timing and its influence on vegetation productivity and early season surface water cover in the Prudhoe Bay Oilfields
Authors: Bergstedt Helena , Jones Benjamin , Walker Donald , Pierce Jana , Bartsch Annett , Pointner Georg
Published: March 2021

Increased industrial development in the Arctic has led to a rapid expansion of infrastructure in the region. Past research shows that infrastructure in the form of roads, pipelines and various building types impacts the surrounding landscape directly and indirectly by changing vegetation patterns, locally increasing ground temperatures, changing the local hydrology, introducing road dust into the natural environment, and affecting the distribution and timing of seasonal snow cover. Localized impacts of infrastructure on snow distribution and snow melt timing and duration feedbacks into the coupled Arctic system causing a series of cascading effects that remain poorly understood.  In this study, we quantify spatial and temporal patterns of snow-off dates in the Prudhoe Bay Oilfields (PBO), North Slope, Alaska using multispectral remote sensing data from the Sentinel-2 constellation. The Sentinel-2 satellite constellation provides good spatial and temporal coverage of Arctic regions with adequate spatial resolution to quantify and monitor infrastructure impacts on the natural environment in polar regions. We derive the Normalized Difference Snow Index (NDSI) to quantify the presences and absences of snow on a pixel-by-pixel basis between 2015 and 2020. Additional indices, like the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Water Index (NDWI) were derived to understand linkages between patterns in vegetation and surface hydrology, respectively, to patterns in snow-off dates that are influenced by the presence and type of infrastructure on a regional basis at PBO. Newly available infrastructure data sets derived from Sentinel-1 and 2 data were employed to quantify differences in snow melt patterns in relation to distance to roads and other types of infrastructure. Near-surface ground temperature measurements from multiple transects oriented in a perpendicular direction from the road up to 100 m provided ground-truth observations for snow-off timing derived from the remote sensing analysis. Our results from the regional remote sensing analysis show a relationship between snow-off date and distance to different types of infrastructure that vary by their use and traffic load during the snowmelt period as well as their orientation relative to the prevailing wind direction. Results from field data observations indicate that the early onset of snowmelt near heavily traveled infrastructure corridors impacts near-surface soil freezing degree days, vegetation productivity, and waterbody surface cover.
A roadmap for high-resolution satellite soil moisture applications
Authors: Peng Jian , Albergel Clement , Balenzano Anna , Brocca Luca , Cartus Olive , Cosh Michael H. , Crow Wade T. , Dabrowska-Zielinska Katarzyna , Dadson Simon , Davidson Malcolm W.J. , de Rosnay Patricia , Dorigo Wouter , Gruber Alexander , Hagemann Stefan , Hirschi Martin , Kerr Yann H. , Lovergine Francesco , Mahecha Miguel D. , Marzahn Philip , Mattia Francesco ,   rest of the team
Published: March 2021

This contribution presents the main findings of a recently published review on high-resolution satellite soil moisture applications (https://doi.org/10.1016/j.rse.2020.112162). The scientific community has made significant progress in estimating soil moisture from satellite-based Earth observation data, particularly in operationalizing coarse-resolution (25-50 km) soil moisture products. This presentation summarizes existing applications of satellite-derived soil moisture products and identifies gaps between the characteristics of currently available soil moisture products and the application requirements from various disciplines. This presentation also discusses the efforts devoted to the generation of high-resolution soil moisture products from satellite Synthetic Aperture Radar (SAR) data such as Sentinel-1 C-band backscatter observations and through downscaling of existing coarse-resolution microwave soil moisture products. Open issues and future opportunities of soil moisture remote sensing are discussed, providing guidance for the further development of operational soil moisture products and for bridging the gap between the soil moisture user and supplier communities.

The published review is:

Peng, J., Albergel, C., Balenzano, A., Brocca, L., Cartus, O., Cosh, M.H., Crow, W.T., Dabrowska-Zielinska, K., Dadson, S., Davidson, M.W.J., de Rosnay, P., Dorigo, W., Gruber, A., Hagemann, S., Hirschi, M., Kerr, Y.H., Lovergine, F., Mahecha, M.D., Marzahn, P., Mattia, F., Musial, J.P., Preuschmann, S., Reichle, R.H., Satalino, G., Silgram, M., van Bodegom, P.M., Verhoest, N.E.C., Wagner, W., Walker, J.P., Wegmüller, U., & Loew, A. (2021). A roadmap for high-resolution satellite soil moisture applications – confronting product characteristics with user requirements. Remote Sensing of Environment, 252, 112162
Randomness in the amount of rain in LES with Lagrangian microphysics
Authors: Zmijewski Piotr , Dziekan Piotr , Pawlowska Hanna
Published: March 2021

Lagrangian, particle-based models are an emerging method for detailed modeling of cloud microphysics. In these models, a relatively small number of "super-droplets" is used to represent all hydrometeors. Each super-droplet represents vast number of hydrometeors that have the same properties. The most popular method for solving collision-coalescence in these particle-based models is the all-or-nothing algorithm. In this algorithm, collision-coalescence of droplets within a spatial cell is modeled with a stochastic process. The number of trials is proportional to the number of super-droplets, which is significantly lower than the number of hydrometeors. Therefore the variance of the number of hydrometeors with a given size is higher in the super-droplet algorithm than it would be if every droplet was modeled separately. The increase of this variability depends on the number of super-droplets. We use the University of Warsaw Lagrangian Cloud Model (UWLCM) to analyse how the randomness in the collision-coalescence algorithm affects the amount of precipitation in large eddy simulations of warm clouds.
Super-resolution in Structural Geological Models.
Authors: Qazi Mustaeen Ur Rehman , Wellmann Florian
Published: March 2021

Structural geological models are often calculated on a specific spatial resolution – for example in the form of grid representations, or when surfaces are extracted from implicit fields. However, the structural inventory in these models is limited by the underlying mathematical formulations. It is therefore logical that, above a certain resolution, no additional information is added to the representation.

We evaluate here if Deep Neural Networks can be trained to obtain a high-resolution representation based on a low-resolution structural model, at different levels of resolution. More specifically, we test the use of state-of-the-art Generative Adversarial Networks (GAN’s) for image superresolution in the context of 2-D geological model sections. These techniques aim to learn the hidden structure or information in high resolution image data set and then reproduce highly detailed and super resolved image from its low resolution counterpart. We propose the use of Generative Adversarial Networks GANS for super resolution of geological images and 2D geological models represented as images. In this work a generative adversarial network called SRGAN has been used which uses a perceptual loss function consisting of an adversarial loss, mean squared error loss and content loss for photo realistic image super resolution. First results are promising, but challenges remain due to the different interpretation of color in images for which these GAN’s are typically used, whereas we are mostly interested in structures.