bluuebunny/crossref_metadata_2025 huggingface dataset:
Parameters controlling mid-Holocene highstand in Glacial Isostatic Adjustment modelling
Authors: Li Tanghua , Chua Stephen , Khan Nicole , Wu Patrick , Horton Benjamin
Published: March 2021

Holocene relative sea-level (RSL) records from regions distal from ice sheets (far-field) are commonly characterized by a mid-Holocene highstand, when RSL reached higher than present levels. The magnitude and timing of the mid-Holocene highstand varies spatially due to hydro-isostatic processes including ocean syphoning and continental levering. While there are open questions regarding the timing, magnitude and source of ice-equivalent sea level in the middle to late Holocene.

Here, we compare Glacial Isostatic Adjustment (GIA) model predictions to a standardized database of sea-level index points (SLIPs) from Southeast Asia where we have near-complete Holocene records. The database has more than 130 SLIPs that span the time period from ~9.5 ka BP to present. We investigate the sensitivity of mid-Holocene RSL predictions to GIA parameters, including the lateral lithospheric thickness variation, mantle viscosity (both 1D and 3D), and deglaciation history from different ice sheets (e.g., Laurentide, Fennoscandia, Antarctica).

We compute gravitationally self-consistent RSL histories for the GIA model with time dependent coastlines and rotational feedback using the Coupled Laplace-Finite Element Method. The preliminary results show that the timing of the highstand is mainly controlled by the deglaciation history (ice-equivalent sea level), while the magnitude is dominated by Earth parameters (e.g., lithospheric thickness, mantle viscosity). We further investigate whether there is meltwater input during middle to late Holocene and whether the RSL records from Southeast Asia can reveal the meltwater source, like Antarctica.
Multidisciplinary analyses for mapping and evaluating kinematics and stress/strain field at active faults and fissures at NE Rift, Mt Etna (Italy)
Authors: Falsaperla Susanna , Tibaldi Alessandro , Corti Noemi , De Beni Emanuela , Bonali Fabio L. , Langer Horst , Neri Marco , Cantarero Massimo , Reitano Danilo , Fallati Luca
Published: March 2021

Strategies for disaster risk reduction in volcanic areas are mostly driven by multidisciplinary analyses, which offer effective and complementary information on complex geomorphological and volcano-tectonic environments. For example, quantification of the offset at active faults and fissures is of paramount importance to shed light on the kinematics of zones prone to deformation and/or seismic activity. This provides key information for the assessment of seismic hazard, but also for the identification of conditions that may favor magma uprising and opening of eruptive fissures.

Here we present the results of a study encompassing detailed geological, structural and seismological observations focusing on part of the NE Rift at Etna volcano (Italy). The area is situated at an elevation ranging between 2700 and 1900 m a.s.l. where harsh meteorological conditions and difficult logistics render classical field work a troublesome issue. In order to bypass these difficulties, high-resolution (2.8 cm) UAV survey has been recently completed. The survey highlights the presence of 250 extension fractures, 20 normal fault segments, and 54 eruptive fissures. The study allows us to quantify the kinematics at extensional fractures and normal faults, obtaining an extension rate of 1.9 cm/yr for the last 406 yr. With a total of 432 structural data collected by UAV along with SfM photogrammetry, this work also demonstrates the suitability of the application of such surveys for the monitoring of hazardous zone.
Detection and monitoring of hydrothermal alteration by Principal Component Analysis applied on UAS derived optical data, Vulcano Island - Italy
Authors: Müller Daniel , Bredemeyer Stefan , Zorn Edgar , De Paolo Erica , Walter Thomas
Published: March 2021

Modern UAS (unmanned aircraft system), light weight sensor systems and new processing routines allow us to gather optical data of volcanoes at a high resolution. However, due to the typically poor colorization, our ability to investigate and interpret such data is limited. Further, the information stored in the red, green and blue channel (RGB) is correlated. This makes any analysis a 3 dimensional task. Principal Component Analysis (PCA) helps us to overcome these problems by decorrelating the original band information and generating a variance representation of the original data. Therefore PCA is a suitable tool to detect optical anomalies, as might be caused by volcanic degassing and associated processes.

Applied in a case study at La Fossa Cone (Vulcano Island - Italy), the PCA showed a high efficiency for the detection and pixel based extraction of areas subject to hydrothermal alteration and sulfur deposition. We observed a broad alteration zone surrounding the active fumarole field, but also heterogeneities within, indicating a segmentation. Systematic variations in color and density distribution of sulfur deposits have implications for structural controls on the degassing system.

Combining the efficiency of PCA with the high resolution of UAS derived data, this methodology has a high potential to be employed in the spatio-temporal monitoring of volcanic hydrothermal systems and processes at surface.

 
Effects of three floating treatment wetland arrangements on the flow field of a channel
Authors: Yamasaki Taís , Janzen Johannes
Published: March 2021

Floating treatment wetlands (FTWs) constitute a nature-based solution that promotes water, stormwater and wastewater treatment by using vegetation growing hydroponically on top of a floating mat. One of the advantages of FTWs is not requiring land space to install them, since FTWs are put directly on the water body's surface. Consequently, FTWs can have the potential to affect the flow field, inducing preferential paths and short-circuit, for instance, which may be controlled by how the FTWs are arranged on the water surface. This study aims to numerically simulate the flow field for three FTW arrangements displayed in a channel reach, in order to assess the hydrodynamic differences between each arrangement. In Arrangement 1, three FTWs in series will be installed at the channel center. Arrangement 2 will be formed by three FTWs in series, each one spanning the channel width. Finally, Arrangement 3 will be formed by two FTWs displayed at each margin of the channel. The total FTW volume will remain constant for all arrangements. The simulations will be performed in Computational Fluid Dynamics (CFD), using a validated FTW model from laboratory experiments.
A methodical approach to analyze the effect of river morphology and hydrology on fish fauna in the inner-Alpine space
Authors: Schmölz Katja , Felber Agnes , Mark Wolfgang , Thaler Melanie , Wieser Josef , Persiano Simone , Bertoldi Giacomo , Tasser Erich
Published: March 2021

River ecosystems are diverse and dynamic habitats which are strongly influenced by direct and indirect consequences of human interventions. Several initiatives have been started all over Europe to fulfill the European guidelines for the protection of the local water bodies, but a standardized procedure fulfilling all relevant aspects and parameters of the Water Framework Directive (WFD) does not exists. To evaluate water quality, the WFD predefines biotic and abiotic parameters, such as morphology, hydrology, water chemistry as well as biological quality components, including fish fauna. In this context, we propose a new methodological approach based on salmonid fish populations to assess river quality. Our approach is based on European standardization of the Austrian and Italian methods and it has been tested in the context of an international fish project in 81 stream sections in the European Alps, having homogeneous morphological characteristics. The assessment procedure is composed of a set of 11 indicators, which were selected to evaluate longitudinal and lateral morphological and hydrological conditions: stream passability, reproduction sites, riverine dynamic, shoreline, shoreline vegetation, structure, substrate and degree of hydrological disturbance, a descent speed indicator as well as discharge conditions of hydropeaking. The indicators were then combined to 3 indices, namely: morphology index (IM), hydrology index (IH) and hydromorphology index (IHM), to create a holistic picture of the total stream conditions. The indicator and index definition, the compilation and practical testing of the data entry form in the field, as well as the calculation of the values, were carried out jointly by a team of experts. The combination of that created a new hydromorphology index (IHM) for Alpine streams. The application of the proposed method was shown in 31 river streams in South Tyrol (Italy) and Tyrol (Austria) covering a wide range of different anthropogenic changes and pressure degree, which enabled the trial of the methodology and the refinement of the indicators and indices. The outcomes of our study lead to interesting insights regarding applicability, strengths and weaknesses of the proposed approach.
The World Heritage Naracoorte Caves beyond 500 ka: U-Pb dating and charcoal analysis from speleothems with implications for Pleistocene vertebrate fossil deposits
Authors: Weij Rieneke , Woodhead Jon , Reed Liz , Sniderman Kale , Hellstrom John , Drysdale Russell
Published: March 2021

Under the current rapid global warming, studying how environments responded to past climate change becomes increasingly important to better understand what impact climate variability has on regional flora and fauna. Our new multi-proxy study to the World Heritage Naracoorte Caves in southern Australia provides a unique window into the past climate as they are heavily decorated with speleothems but also contain in-fill deposits rich in Pleistocene vertebrate fossils including the extinct Australian megafauna. Until now, these speleothems have been dated using U-Th series and the fossil-bearing sediments with Optical Stimulated Luminescence and Electro Spin Resonance techniques, but only up to ca. 500 ka. We have U-Pb dated speleothems from the Naracoorte Caves for the first time and extended the record beyond 500 ka. We combined precise chronology with analyses of pollen and charcoal within the speleothems which allows us to better understand how southern Australia’s climate and its vegetation changed during the Quaternary. It also provides a unique insight into the timing and extent of cave opening with important potential for much older vertebrate fossil deposits than previously thought.
Enhancing WRF Model Forecasts by Assimilating High-Resolution GPS-Derived Water-Vapor Maps combined with METEOSAT-11 Data 
Authors: Reuveni Yuval , Leontiev Anton , Rostkier-Edelstein Dorita
Published: March 2021

Improving the accuracy of numerical weather predictions still poses a challenging task. The lack of sufficiently detailed spatio-temporal real-time in-situ measurements constitutes a crucial gap concerning the adequate representation of atmospheric moisture fields, such as water vapor, which are critical for improving weather predictions accuracy. Information on total vertically integrated water vapor (IWV), extracted from global positioning systems (GPS) tropospheric path delays, can enhance various atmospheric models at global, regional, and local scales. Currently, numerous existing atmospheric numerical models predict IWV. Nevertheless, they do not provide accurate estimations compared with in-situ measurements such as radiosondes. In this work, we demonstrate a novel approach for assimilating 2D IWV regional maps estimations, extracted from GPS tropospheric path delays combined with METEOSAT satellite imagery data, to enhance Weather Research and Forecast (WRF) model predictions accuracy above the Eastern Mediterranean area. Unlike previous studies, which assimilated IWV point measurements, here, we assimilate quasi-continuous 2D GPS IWV maps, augmented by METEOSAT-11 data, over Israel and its surroundings. Using the suggested approach, our results show a decrease of more than 30% in the root mean square error (RMSE) of WRF forecasts after assimilation relative to the standalone WRF when verified against in-situ radiosonde measurements near the Mediterranean coast. Furthermore, substantial improvements along the Jordan Rift Valley and Dead Sea Valley areas are achieved when compared to 2D IWV regional maps. Improvements in these areas suggest the importance of the assimilated high resolution IWV maps, in particular when assimilation and initialization times coincide with the Mediterranean Sea Breeze propagation from the coastline to highland stations.
Assessment and Improvement of Noah-MP over the Tibetan grasslands in growing season
Authors: Sun Shuang , Zheng Donghai , Liu Shaomin , Xu Ziwei , Xu Tongren , Zheng Hui , Yang Xiaofan
Published: March 2021

The Tibetan grasslands has very strong land-air interactions and plays an important role in the regional climate system of the Tibetan Plateau and understanding of land-air interactions in the Tibetan grasslands is significantly important for the sustainable development of it under the climate change. In this paper, we assessed the Noah-MP by conducting ensemble experiments for analyzing the sensitive physical processes, and selected the optimal combinations of parameterization options at four alpine meadow sites in the Tibetan grassland ecosystems. Measurements collected from four study sites over the Tibetan grassland ecosystems in the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) are used. The results showed that the dynamic vegetation (Dveg), the canopy stomatal resistance (Crs), the runoff and the groundwater (Run) and the surface exchange coefficient (Sfc) physical processes are the most sensitive control physical processes for energy and water fluxes in the Tibetan grassland ecosystems. Importantly, the optimal combination of parameterization options in Noah-MP overestimates the sensible heat flux (H) and underestimates soil moisture (θ) obviously. After finding the problems in the simulations outputed by the optimal combination of parameterization options, two groups of improved experiments were conducted to find out the reason. We found that the improved calculation of the surface exchange coefficient can alleviate the overestimation H, and the improved method of soil parameters considering the soil organic carbon (SOC) and an exponential form of root vertical distribution for each soil layers can effectively solve the underestimation of θ at all four sites.
Surface-groundwater interactions in karst: overview, concept and mapping
Authors: Ravbar Natasa , Mayaud Cyril , Blatnik Matej , Petrič Metka
Published: March 2021

Under special meteorological and hydrological circumstances, shallow karst areas and karst poljes may experience surface water overflow. As a result, surface- groundwater interaction occurs usually creating intermittent lakes. Although human settlements and activities have traditionally adapted to these natural conditions, extensive temporary floods are classified among the most common natural disasters in karst. On the other hand, intermittent lakes are considered as natural reservoirs of excess recharge and good flood regulators in the lower parts of river basins. Due to specific ecohydrological processes and environmental conditions, these areas host unique wetland ecosystems with high levels of biodiversity and provide various ecosystem services, such as ecological productivity, photosynthesis and carbon storage. Given the dynamic nature of hydrological processes in karst aquifers, a distinctive feature of the phenomena described is its high variability of occurrence and duration. Therefore, the identification, characterization as well as the determination of the spatial dimension of flood levels is a challenging task. Focusing on the Slovenian karst, a literature review and analysis of topographical and hydrological data of the selected study areas was conducted. The hydrological analyses were based on long-term monitoring data from Slovenian Environmental Agency and partly on the authors' own database of field measurements and knowledge of the areas concerned. Consequently, the conceptual framework and the key criterion for the determination and recording of areas subject to temporary flooding were developed. A systematic survey reveals the significance of the extent, duration and frequency of flooding. Evaluation results are useful to designers of various water policies and management mechanisms for flood mitigation and protection of special habitats. Observing trends in the spatial and temporal dynamics of flood levels is also valuable for understanding how and to what extent karst aquifers are vulnerable to environmental changes. Finally, the analyses also enable prediction of the effects of these changes on other parts of the environment (e.g., hydrophilic habitats).
Uncertainty analysis of solar/geomagnetic activity impact on terrestrial variables, based on the information theory 
Authors: Mares Ileana , Mares Constantin , Dobrica Venera , Demetrescu Crisan
Published: March 2021

The present study aims at investigating uncertainty of external factors, namely the solar/geomagnetic forcing on the terrestrial variables as the Danube discharge and the atmospheric indices at the large scale. Our analysis was performed separately for each season, for two time periods, 1901-2000 and 1948-2000.

The relationship between terrestrial variables and external factors was achieved by applying the information theory elements as synergy, redundancy, total correlation and transfer entropy. 

The results differ depending on the time of year and the analysed variables.

From this analysis resulted that the two external forcings can be considered together as predictors for certain cases, while for others they are very redundant, therefore the one that produces the lowest uncertainty connection was selected.
Differences in regular and storm time ionospheric variability at magnetically conjugated locations of the Northern and Southern Hemisphere 
Authors: Buresova Dalia , Habarulema John Bosco , Araujo-Pradere Eduardo , Tshisaphungo Mpho , Watermann Jurgen , Lastovicka Jan
Published: March 2021

The paper is focused on differences/similarities in regular daily ionospheric variability and in the ionospheric response to CME- and CIR/CHSS-related magnetic disturbances above magnetically conjugated ionospheric stations located at Northern and Southern Hemisphere. We analysed variability of critical frequency foF2 and the F2 layer peak height hmF2 obtained for European-African sector for initial, main and recovery phases of magnetic storms of different intensity, which occurred within the last two solar cycles. We also used exclusively GPS-based detection methods, specifically information on TEC, TEC deviations in space and time from a background reference (dTEC), and the Rate of TEC change in time (ROT), all inferred from GPS receiver networks in Europe and Africa to compare behavior of Large Scale Traveling Ionospheric Disturbances (LSTIDs) at both hemispheres. We conclude that hemispheric conjugacy of LSTID is highly probable during both CME- and CIR/CHSS-related storms while interhemispheric circulation rather unlikely but still occurring during some periods.
Biomass burning in the southern hemisphere UTLS: GLORIA trace gas observations during SouthTRAC 2019 to evaluate the CAMS model 
Authors: Johansson Sören , Höpfner Michael , Friedl-Vallon Felix , Glatthor Norbert , Ungermann Jörn , Wetzel Gerald
Published: March 2021

We present trace gas measurements obtained by the airborne imaging limb sounder GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) that has been operated onboard the German HALO (High Altitude and Long Range) research aircraft above the South Atlantic during the SouthTRAC campaign between September and November 2019. We show retrieval results as two-dimensional trace-gas distributions derived from GLORIA observations in the UTLS (Upper Troposphere Lower Stratosphere) region above South America and the Atlantic Ocean. Targeted gases are, amongst others, O3, HNO3, PAN, C2H6, and HCOOH. Using trajectories from the HYSPLIT model, measured pollution trace gas plumes are linked to possible regions of origin. Emission sources are connected to large scale biomass burning events in central Africa, South America and Australia. In our contribution, we compare these GLORIA measurements with results of the CAMS (Copernicus Atmosphere Monitoring Service) reanalysis model. We show that there are very delicate structures of pollutant trace gas distributions in the South Atlantic UTLS, and that CAMS generally is able to reproduce measured distributions of pollutants. Quantitatively, PAN volume mixing ratios are captured quite well by the model, which however underestimates the concentrations of C2H6 and in particular of HCOOH. Furthermore, biomass burning emissions from the beginning of the intensive Australian fires in November 2019, which are measured by GLORIA in thin filaments are not reproduced by the model.
The Vertical Coseismic Deformation Field of the Samos-Izmir Earthquake (Mw6.9)
Authors: Erkoç Muharrem Hilmi , Özarpacı Seda , Özdemir Alpay , Eskiköy Figen , Ayruk Efe Turan , Farimaz İlay , Doğan Uğur , Ergintav Semih
Published: March 2021

The Samos-Izmir Earthquake (Mw=6.9) of October 30, 2020 is among the strongest earthquakes that occurred in recent years throughout the Eastern Aegean. The epicenter of this earthquake was 14 km away from Samos Island and 25 km away from Gümüldür-İzmir region. The local tsunami with the wave heights reaching ~2m was triggered by the mainshock. The most affected areas were Sigacik and Akarca in Tukey (Yalciner et. al.,2020) and Vathy Town (NE Samos Island) in Greece (Triantafyllou et. al.,2020).

In this study, we present an estimation of co-seismic deformations using an indirect approach based on GNSS, InSAR and Tide Gauge data. GNSS time series were used from 25 continuous GNSS stations data obtained from TUSAGA-Aktif in Turkey and NOANET in Greek, and the campaign GNSS measurement for 10 GNSS sites located at the western Turkey coast has been carried out after the earthquake. Moreover, InSAR deformation analyses have been performed using Sentinel-1 data. In addition, relative sea level changes have been analyzed in KOS, PLOMARI, and MENTES tide gauge stations.

The vertical components of GPS stations have shown 10 cm uplift in Samos Island and 10 cm subsidence in the coast of Turkey. The results of the geodetic (GNSS, InSAR) analysis are consistent with each other. The rise time estimated here may correspond to the time elapsed shortly before the generation of tsunami waves reached up to 6 meters that propagated rapidly and caused significant damage around the source region. Also, it has been seen that whereas relative sea level in KOS and PLOMARI tide gauge stations are affected by the local tsunami, but relative sea level changes could not be observed in the MENTES station.
3D Modelling of the Northern Upper Rhine Graben Crystalline Basement by Joint Inversion of Gravity and Magnetic Data
Authors: Frey Matthis , Weinert Sebastian , Bär Kristian , van der Vaart Jeroen , Dezayes Chrystel , Calcagno Philippe , Sass Ingo
Published: March 2021

The crystalline basement of the Upper Rhine Graben presents an attractive target for deep geothermal projects due to its favourable temperatures and its high potential as a fractured and faulted reservoir system. It is already exploited at several sites, e.g. Soultz-sous-Forêts or Landau, and further projects are currently planned or under development. The crystalline units are furthermore the main source of radiogenic heat production and thus, together with the shallow Moho depth and convective heat transport along large fault zones, significantly contributing to the crustal temperature field. For these reasons, we developed the most detailed 3D geological model of the basement in the northern Upper Rhine Graben to date within the Interreg NWE DGE-ROLLOUT and Hesse 3D 2.0 projects. Due to the small number of very deep boreholes as well as seismic profiles reaching the basement beneath the locally more than 5 km thick sedimentary cover, we additionally used high-resolution magnetic and gravity datasets. In contrast to common deterministic modelling approaches, we performed a stochastic joint inversion of the geophysical data by applying a Monte Carlo Markov Chain algorithm. This method generates a large set of random but valid models, which enables a statistical evaluation of the results, e.g. concerning the model uncertainties. For a realistic attribution of the model, we used existing petrophysical databases of the region and measured the magnetic susceptibility of more than 430 rock samples. As a result of the inversion, high-resolution voxel models of the density and susceptibility distribution were generated, allowing conclusions about the composition and structure of the crystalline crust, which leads to a reduction of uncertainties and risks associated with deep geothermal drillings in the northern Upper Rhine Graben. Furthermore, our model will serve as a basis for realistic simulations of heat transport processes in the fractured basement and a meaningful assessment of the deep geothermal potential in the future.
Statistical relations between in-situ measured Bz component and thermospheric density variations
Authors: Kroisz Sofia , Drescher Lukas , Temmer Manuela , Krauss Sandro , Süsser-Rechberger Barbara , Mayer-Gürr Torsten
Published: March 2021

Through advanced statistical investigation and evaluation of solar wind plasma and magnetic field data, we investigate the statistical relation between the magnetic field Bz component, measured at L1, and Earth’s thermospheric neutral density. We will present preliminary results of the time series analyzes using in-situ plasma and magnetic field measurements from different spacecraft in near Earth space (e.g., ACE, Wind, DSCOVR) and relate those to derived thermospheric densities from various satellites (e.g., GRACE, CHAMP). The long and short term variations and dependencies in the solar wind data are related to variations in the neutral density of the thermosphere and geomagnetic indices. Special focus is put on the specific signatures that stem from coronal mass ejections and stream or corotating interaction regions.  The results are used to develop a novel short-term forecasting model called SODA (Satellite Orbit DecAy). This is a joint study between TU Graz and University of Graz funded by the FFG Austria (project “SWEETS”).
Testing non-linear amplification factors used in ground motion models
Authors: Loviknes Karina , Schorlemmer Danijel , Cotton Fabrice , Reddy Kotha Sreeram
Published: March 2021

Non-linear site effects are mainly expected for strong ground motions and sites with soft soils and more recent ground-motion models (GMM) have started to include such effects. Observations in this range are, however, sparse, and most non-linear site amplification models are therefore partly or fully based on numerical simulations. We develop a framework for testing of non-linear site amplification models using data from the comprehensive Kiban-Kyoshin network in Japan. The test is reproducible, following the vision of the Collaboratory for the Study of Earthquake Predictability (CSEP), and takes advantage of new large datasets to evaluate whether or not non-linear site effects predicted by site-amplification models are supported by empirical data. The site amplification models are tested using residuals between the observations and predictions from a GMM based only on magnitude and distance. When the GMM is derived without any site term, the site-specific variability extracted from the residuals is expected to capture the site response of a site. The non-linear site amplification models are tested against a linear amplification model on individual well-recording stations. Finally, the result is compared to building codes where non-linearity is included. The test shows that for most of the sites selected as having sufficient records, the non-linear site-amplification models do not score better than the linear amplification model. This suggests that including non-linear site amplification in GMMs and building codes may not yet be justified, at least not in the range of ground motions considered in the test (peak ground acceleration < 0.2 g).
Variability of the circulation in the western North Atlantic and its impact on deep-water oxygen concentrations in the St. Lawrence Estuary on the western continental shelf: evidence from observations
Authors: Jutras Mathilde , Dufour Carolina , Mucci Alfonso , Cyr Frédéric , Gilbert Denis
Published: March 2021

Oxygen concentrations in the deep waters of the Lower St. Lawrence Estuary, in eastern Canada, have decreased by 50% over the past century, reaching hypoxic levels. To study the causes of this deoxygenation, we applied a mixing model (an extended multi-parameter analysis - eOMP) to data collected in the St. Lawrence Estuary since the 1970s and from the late 1990s to 2018. This method accounts for diapycnal mixing and can distinguish between the physical and biogeochemical causes of deoxygenation. The eOMP reveals that, in recent years, most of the deoxygenation of deep waters of the St. Lawrence Estuary is due to a change in the circulation pattern in the western North Atlantic. Since 2008, the Slope Sea and the deep waters of the St. Lawrence Estuary are fed by an increasing amount of oxygen-poor North Atlantic Central Waters (NACW), transported by the Gulf Stream, at the expense of oxygen-rich Labrador Current Waters (LCW). The oxygenation level of the St. Lawrence Estuary therefore reflects what is happening in the western North Atlantic. In contrast, the eOMP shows that, from the 1970s to the late 1990s, biogeochemical changes such as local eutrophication and variations in oxygen consumption rates in the North Atlantic dominated the deoxygenation. 

Further analyses suggest that the variability in the LCW:NACW ratio in the Slope Waters is mainly controlled by the Scotian Shelf-break Current, an extension of the Labrador Current, and not by the position or strength of the Gulf Stream, as often suggested. When the Labrador Current is strong, little of the southward flowing Labrador Current waters follow the coast all the way to the Scotian Shelf, and most of these waters are deviated east towards the North Atlantic. The opposite is true when the Labrador Current is weak. We will present some analysis of LCW trajectories in different conditions and discuss their potential drivers, based on a high resolution model. Overall, our results highlight the primary role of the Labrador Current in determining (i) the oxygen concentration and other water properties on the western North Atlantic continental shelf and slope, and (ii) the advection of fresh Labrador Current Water into the subpolar North Atlantic, with possible implications on the thermohaline and gyre circulation.
Regional Climate Model Inter-Comparison for Antarctica within a Data Science Framework
Authors: Carter Jeremy , Leeson Amber , Orr Andrew , Kittel Christoph , van Wessem Melchior
Published: March 2021

Understanding the surface climatology of the Antarctic ice sheet is essential if we are to adequately predict its response to future climate change. This includes both primary impacts such as increased ice melting and secondary impacts such as ice shelf collapse events. Given its size, and inhospitable environment, weather stations on Antarctica are sparse. Thus, we rely on regional climate models to 1) develop our understanding of how the climate of Antarctica varies in both time and space and 2) provide data to use as context for remote sensing studies and forcing for dynamical process models. Given that there are a number of different regional climate models available that explicitly simulate Antarctic climate, understanding inter- and intra model variability is important.

Here, inter- and intra-model variability in Antarctic-wide regional climate model output is assessed for: snowfall; rainfall; snowmelt and near-surface air temperature within a cloud-based virtual lab framework. State-of-the-art regional climate model runs from the Antarctic-CORDEX project using the RACMO, MAR and MetUM models are used, together with the ERA5 and ERA-Interim reanalyses products. Multiple simulations using the same model and domain boundary but run at either different spatial resolutions or with different driving data are used. Traditional analysis techniques are exploited and the question of potential added value from more modern and involved methods such as the use of Gaussian Processes is investigated. The advantages of using a virtual lab in a cloud based environment for increasing transparency and reproducibility, are demonstrated, with a view to ultimately make the code and methods used widely available for other research groups.
Projected changes in frequency of compound events of strong wind and low temperature in EURO-CORDEX climate models
Authors: Plavcová Eva , Lhotka Ondřej , Stryhal Jan
Published: March 2021

Compound events of weather extremes considerably affect various sectors of human society and natural environment and therefore it is essential to understand projected changes of their characteristics in the future climate. We focus on the combination of low temperature and high wind velocity, because their compound effect strongly influences human thermal comfort in cold weather, as characterized by the wind chill factor. In our study, we analyse frequency of this extreme events and projected changes of their characteristics in simulations of RCMs from the EURO-CORDEX project. We investigate a set of 9 simulations of 3 different RCMs driven by 3 different global climate models which allow us to analyse the influence of driving data on the RCM’s outputs. We focus on the Central European domain defined between 48–52°N and 10–19°E. The frequency of the compound events from historical simulations over 1970-2100 are compared to the projected frequencies under the RCP4.5 and RCP8.5 emission scenarios for the end of the 21st century (2070-2100). Since local climate is relatively tightly linked to a large-scale atmospheric circulation over Europe in winter, we also evaluate links of the compound events to the atmospheric circulation.
Optical readout design for a MEMS semi-absolute pendulum gravimeter
Authors: Utting Phoebe , Hammond Giles , Prasad Abhinav , Middlemiss Richard
Published: March 2021

Gravimetry has many useful applications from volcanology to oil exploration; being a method able to infer density variations beneath the ground. Therefore, it can be used to provide insight into subsurface processes such as those related to the hydrothermal and magmatic systems of volcanoes. Existing gravimeters are costly and heavy, but this is changing with the utilisation of a technology most notably used in mobile phone accelerometers: MEMS –(Microelectromechanical-systems). Glasgow University has already developed a relative MEMS gravimeter and is currently collaborating with multiple European institutions to make a gravity sensor network around Mt Etna - NEWTON-g. A second generation of the MEMS sensor is now being designed and fabricated in the form of a semi-absolute pendulum gravimeter. Gravity data for geodetic and geophysical use were provided by pendulum measurements from the 18th to the 20th century. However, scientists and engineers reached the limit of fabrication tolerances and readout accuracy approximately 100 years ago. With nanofabrication and modern electronics techniques, it is now possible to create a competitive pendulum gravimeter again. The pendulum method is used to determine gravity values from the oscillation period of a pendulum with known length. The current design couples two pendulums together. Here, an optical shadow-sensor pendulum readout technique is presented. This employs an LED and split photodiode set-up. This optical readout can provide measurements to sub-nanometre precision, which could enable gravitational sensitivities for useful geophysical surveying. If semi-absolute values of gravity can be measured, then instrumental drift concerns are reduced. Additionally, the need for calibration against commercial absolute gravimeters may not be necessary. This promotes improved accessibility of gravity measurements at an affordable cost.
Microcontinent cleaving and enigmatic proto subduction events (?): The role of transpressional transforms in plate tectonics of the Indian and North Atlantic Oceans
Authors: Longley Luke , Martin Lauren , Satchwell Becky , Tomlinson Liberty , Phethean Jordan
Published: March 2021

Recent advances in knowledge have led to the recognition of continental crust beneath the Comoros islands offshore East Africa and conflicting fracture zone patterns in isolated regions of the Indian ocean. Furthermore, whilst the presence of continental crust within the Davis Straight has been known for some time, its origin remains debated.

Here, using gravity lineament analysis, plate kinematic modelling, seismic reflection interpretations, and 3D crustal thickness inversions (constrained by a new composite sedimentary thickness dataset), we investigate the origin of microcontinents and proto-subduction events in the Western Somali Basin, Indian Ocean, and the Labrador Sea. We find the role of plate motion changes, which induce transpression along active transform faults, play a critical role in the cleaving of the Comoros microcontinent and inducing previously poorly understood plate convergence and missing crustal sections along the Chain and Owen ridges. Furthermore, the temporal and spatial patterns of thrust and normal faulting in the Davis Straight indicates an analogous mechanism emplaced continental crust in this region, suggesting a generic and predictable mechanism may be applicable to the production of this type of microcontinent around the globe. The Davis Straight proto microcontinent (i.e., incompletely rifted microcontinent) began development during the 53 Ma spreading axis reorientation and ceased separation at 33 Ma, when the basin became extinct. We postulate that the extinction of ocean spreading in the Labrador Sea, and possibly also the Western Somali Basin, may have been influenced by increasing transpression across long-offset fracture zones and suggest further study of this phenomenon.
AMOC Evolution at 47°N in the Last Decades in Observations and a High-Resolution Ocean Model
Authors: Wett Simon , Rhein Monika , Biastoch Arne , Böning Claus , Getzlaff Klaus
Published: March 2021

The Atlantic Meridional Overturning Circulation (AMOC) plays an important role for the climate system of Europe and the Arctic. It is responsible for the northward transport of warm and saline water in the upper water column and the southward transport of cold and fresh water in the deep.

Since the early 2000s, observations from ship-based measurements and moorings are available which allow estimates of the individual components of the AMOC. However, the spatial resolution of mooring measurements is coarse and ship-based surveys are mostly done only once a year, adding to the uncertainty of these measurements. Earlier observational studies in the subpolar North Atlantic have found decadal trends of individual AMOC components. However, whether the entirety of the AMOC exhibits a trend remains unclear. Due to the observational limitations, most knowledge about the recent AMOC development is based on model simulations. Comparing these model simulations with observations remains an important task to understand the changes in the AMOC strength in the last decades and improve model representations of the AMOC.

We analyze a realization of the high-resolution VIKING20X ocean model from 1980 to 2019 offering a large overlap with the available observations. We compare it to measurements of the NOAC array at 47°N and sections obtained from repeated ship surveys. We aim to merge observations and model simulation to better estimate recent AMOC changes and increase our understanding of the underlying processes.
Spatially varying ductile structures in fold-and-thrust belts: insights from laboratory experiments
Authors: Roy Sreetama , Bose Santanu , Saha Puspendu
Published: March 2021

Fold and thrust belts (FTBs), formed by the collision of two continental plates, accommodate tectonic convergence through folding and faulting of crustal rocks. The effects of distributed deformation although ubiquitous in all fold-and-thrust belts, regionally occurring ductile structures are often interpreted as an outcome of localized deformation. Our study presents 3D laboratory-scale models using a viscous thin sheet as crustal layer to investigate the evolution of distributed ductile strain in FTBs. Here, we tested the role of mechanical coupling at the basal decollement (i.e., weak versus strong) on the nature of ductile strain variations within a deforming tectonic wedge. Convergence velocity has been kept constant in all experiments to avoid the influence of rate-dependence on viscous rheology. Our results reveal that the mode of wedge growth with changing basal coupling is crucial for varying strain pattern towards the hinterland. Weak decollement models yield a zone of constriction towards the central part of the hinterland, explaining the occurrence of isolated patches of L-tectonites and cross-folds in FTBs; while strong decollement condition allows the gravity-driven flow to be dominant over horizontal shortening, leading to rotation of earlier structures and formation of orogen-parallel recumbent folds, particularly towards the hinterland. The deformation towards the frontal part of the tectonic wedge, irrespective of coupling strength in both models is similar, forming a characteristic pattern of pervasive, hinterland dipping ductile fabrics. We correlate our findings to infer that spatio-temporal variations in basal coupling are responsible for the development of variably occurring ductile structures in FTBs.
Mapping the Bubble Trap Feeding Eruptions of Strokkur Geyser, Iceland
Authors: Eibl Eva P. S. , Müller Daniel , Walter Thomas R. , Allahbakhshi Masoud , Jousset Philippe , Hersir Gylfi P. , Dahm Torsten
Published: March 2021

Geysers are characterized by regular eruptions of hot water fountains. Their internal system consists of a heat source at depth, an often complex crack system and a conduit linking it to the surface. The conduit and crack system is filled with water, steam and gases similar to a volcano. Bubble traps are sometimes and rarely mapped and alternative heat-driven models for geyser eruptions exist.

Using a multidisciplinary, dense and close network of video cameras, seismometers, water pressure sensors and a tiltmeter we studied pool geyser Strokkur in June 2018. These multidisciplinary observations and particle-motion based tremor locations enabled us to derive a schematic cross section describing the driving mechanisms and the fluid dynamic processes within the bubble trap, crack system and conduit. We imaged a bubble trap at 23.7+-4.4 m depth, 13 to 23 m west of the conduit. We divide the eruptive cycle into eruption, refilling of the conduit, gas accumulation in the bubble trap and a trail of bubbles from the bubble trap into the conduit where they collapse at depth and have gained novel insights in understanding the gas accumulation, migration and collapse in such hot geyser systems in different phases of the eruptive cycle.

The dataset of this experiment can be accessed here:

- Eibl, E. P. S., Müller, D., Allahbakhshi, M., Walter, T. R., Jousset, P., Hersir, G. P., Dahm, T., (2020) ' Multidisciplinary dataset at the Strokkur Geyser, Iceland, allows to study internal processes and to image a bubble trap.' GFZ Data Services. DOI: 10.5880/GFZ.2.1.2020.007

- Eibl, E. P. S.; Walter, T.; Jousset, P.; Dahm, T.; Allahbakhshi, M.; Müller, D.; Hersir, G.P. (2020): 1 year seismological experiment at Strokkur in 2017/18. GFZ Data Services. Other/Seismic Network. DOI:10.14470/2Y7562610816
The MINETRAIN project: Lifelong Learning opportunities for mining industry related professionals in real-life underground mining conditions; Dealing with the aftermath of two innovative pilot courses
Authors: Barakos George , Luolavirta Kirsi , Joutsenvaara Jari , Luukkanen Saija , Puputti Hannah Julia , Mischo Helmut
Published: March 2021

Being at the phase of entering the new digital era, the mining industry is constantly facing challenges utilizing the introduction of data-oriented and multi-criteria decision-making concepts, demand for real-time solutions and need for experienced staff. Hence, lifelong updating of knowledge and skills of mining experts has become increasingly important and recognized worldwide as a challenge for developing a sustainable mining sector. It is also well acknowledged that an interdisciplinary understanding of mining professionals over the integrated mine value chain is expected to optimize the efficiency of operations and in turn, enhance the feasibility of mining projects.  Given also the nature of the vast majority of mining activities, practical know-how is of great importance. There are, however, very few opportunities around the world for hands-on training in real mining conditions, and even less so at actual mine sites.

Hence, the idea of transforming abandoned or closing mines into training facilities is becoming more and more attractive among mining industry professionals, academics and researchers. Nevertheless, the theory is far from practice, and such an endeavour is by no means easy. In this concept, the Pyhäsalmi Cu-Zn Mine, in northern Finland is shortly to cease its operations. New activities are being investigated for the post-usage of the mine site. This in mind, Callio has been established as an umbrella organization to offer opportunities for business, development and research projects in the existing unique mine environment. Accordingly, the MINETRAIN project was launched in 2018 to investigate the possibility of utilization of the Pyhäsalmi Mine site for the education of mining experts and students. As a training and educational facility, the Pyhäsalmi mine will provide a globally unique environment, with training possibilities covering topics over the entire Mine Life Cycle; from exploration to mine closure.

To test the feasibility of Pyhäsalmi mine as an educational and training site, two pilot training courses have been developed during the last two years in the context of MINETRAIN, namely Mine Life Cycle and Digital Life of a Mine. The participation was tremendous, and the feedback received from the trainees has been highly positive; the obtained worldwide attraction strongly implies a great interest among mining professionals in practical education. Hence, in this paper, the challenges faced and the lessons learnt from the organization of these pilot courses are discussed with respect to the viable transition of Pyhäsalmi mine to an educational and training underground facility.
Estimating Area Coverage and Volume of Hot Lava by Integrating Multiple Satellite Remote Sensing Techniques
Authors: Bhagwat Ninad , Zhou Xiaobing , Miao Jiaqing
Published: March 2021

Monitoring the regions that are prone to natural hazards is essential in disaster management, since early warnings can be issued. Airborne and space-borne remote sensing techniques are cost-effective in accomplishing the task. Estimating the area and volume of erupted lava can help researchers understand the volcanic processes and impact on land use and land cover. In this study, we developed a new algorithm to estimate areal coverage and volume of exposed hot lava by integrating the space-borne Interferometric Synthetic Aperture Radar (InSAR), thermal infrared, and Normalized Vegetation Distribution Index (NDVI) techniques. We applied this algorithm to the eruption of the East Rift Zone (ERZ) of the Kilauea volcano took place between May and August 2018 and estimated the areal coverage and volume of lava erupted. We compared the results of InSAR to those derived from airborne Light Detection and Ranging (LiDAR), and found that although air-borne LiDAR provides data with higher resolution and accuracy, InSAR is almost as good as LiDAR in monitoring deformed areas and has larger spatial and temporal coverage.