bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of Freeze-Thaw Processes in Soils and Grouting Materials
Authors: Hesse Jan Christopher , Kupfernagel Jan-Henrik , Schedel Markus , Welsch Bastian , Müller Lutz , Sass Ingo
Published: March 2021

Freezing and thawing in the subsurface is often related to complex technical handling of possible influences on the engineered structures (e.g. permafrost or geothermal heat pumps). Freeze-thaw processes in the vicinity of borehole heat exchangers can significantly impair the system. However, for groundwater protection and thermal efficiency, the hydraulic and thermal integrity of such systems must be permanently ensured for the complete operation time. Detailed knowledge on freeze-thaw processes in porous media, such as soils or geotechnical grouts, and the driven parameters, is still pending. Freezing in porous media does not occur as a sudden transition from pure liquid water to the ice phase, but rather within a freezing interval strongly depending on various boundary conditions such as soil type or pore water chemistry. As the content of frozen and unfrozen water has a strong impact on material properties, it is essential to have suitable information about the different factors influencing freezing processes as well as the thermo-hydraulic-mechanical (THM) effects on porous media due to phase change. Thus, a THM laboratory experiment was developed and built to gain more knowledge on freeze-thaw processes and their effects on soil and grouting materials. The experiment consists of a modified triaxial test, enabling for controlled temperature and hydraulic flow conditions, that is combined with an ultrasonic measurement device to determine the unfrozen water content.

In this contribution, results of the THM experiment are presented, whereas the following parameters were investigated: The freezing interval using P-wave velocity, freezing pressure as well as axial and radial volume expansion due to ice formation as well as the influence of hydraulic flow on the ice formation. First, benchmark experiments were conducted on well-characterized solid rock samples to avoid any influence of a variable sample pore structure during the experiments. Further experiments focused on the investigation of soil samples of different texture classes. For upscaling to real scale applications, the experimental findings will be implemented in numerical models.
Impact of Climate Change on Coastal Meadows: a Mesocosm Approach
Authors: Bergamo Thaisa , Ward Raymond , Joyce Christopher , Sepp Kalev
Published: March 2021

Coastal meadows supply a wide range of ecosystem services, including high carbon storage, high plant species richness and a wide variety of habitat types, which supports breeding and migratory bird populations. However, global change (climate change, pollution and environmental degradation) poses several threats to the stability and ecosystem services supplied by coastal meadows. Specifically within the Baltic Sea, recent estimates foresee various degrees of sea level rise along the Estonian coast and salinity is expected to decrease in the eastern Baltic and increase in the west. In order to assess the effects of climate change in coastal wetlands, an investigation of the influence of changes in water level and salinity on coastal wetland plant communities was undertaken. Future scenarios of Estonian coastal wetlands were evaluated using a three-year mesocosm experiment simulating altered environmental conditions. The response of three plant communities (Open Pioneer, Lower Shore and Upper Shore) were assessed in terms of changes in species composition through time. The experiment included 45 mesocosms, 15 per community with 5 treatments (3 replicates per treatment) with control, altered water level and salinity. Exploratory analysis, ANOVA and NMDS, were used to assess changes in the plant communities throughout the duration of the project. Preliminary results show that Open Pioneer is more sensitive to decreased salinity. A decrease in percentage cover of species adapted to high salinity concentration (e.g. Spergularia marina) was observed. On the other hand, Lower Shore didn’t show any clear changes with the treatments. In order to obtain deeper insights, further analysis are needed to reveal complex community shifts under altered physical conditions.
Hydrological functioning of irrigated maize crops in southwest France using Eddy Covariance measurements and a land surface model
Authors: Dare-Idowu Oluwakemi , Jarlan Lionel , Brut Aurore , Le-Dantec Valerie , Rivalland Vincent , Ceshia Eric , Boone Aaron
Published: March 2021

This study aims to analyze the main components of the energy and hydric budgets of irrigated maize in southwestern France. To this objective, the ISBA-A-gs (Interactions between Soil, Biosphere, and Atmosphere) is run over six maize growing seasons. As a preliminary step, the ability of the ISBA-A-gs model to predict the different terms of the energy and water budgets is assessed thanks to a large database of in situ measurements by comparing the single budget version of the model with the new Multiple Energy Balance version solving an energy budget separately for the soil and the vegetation. The in situ data set acquired at the Lamasquere site (43.48o N, 1.249o E) includes half-hourly measurements of sensible (H) and latent heat fluxes (LE) estimated by an Eddy Covariance system. Measurements also include net radiation (Rn), ground heat flux (G), plant transpiration with sap flow sensors, meteorological variables, and 15-days measurements of vegetation characteristics. The seasonal dynamics of the turbulent fluxes were properly reproduced by both configurations of the model with an R² ranging from 0.66 to 0.89, and a root mean square error lower than 48 W m-2. Statistical metrics showed that H was better predicted by MEB with R² of 0.80 in comparison to ISBA-Ags (0.73). However, the difference between the RMSE of ISBA-Ags and MEB during the well-developed stage of the plants for both H and LE does not exceed 8 W m-2. This implies that MEB only has a significant added value over ISBA-Ags when the soil and the canopy are not fully coupled, and over a heterogeneous field. Furthermore, this study made a comparison between the sap flow measurements and the transpiration simulated by ISBA-A-gs and MEB. A good dynamics was reproduced by ISBA-A-gs and MEB, although, MEB (R²= 0.91) provided a slightly more realistic estimation of the vegetation transpiration. Consequently, this study investigated the dynamics of the water budget during the growing maize seasons. Results indicated that drainage is almost null on the site, while the observed values of cumulative evapotranspiration that was higher than the water inputs are related to a shallow ground table that provides supplement water to the crop. This work provides insight into the modeling of water and energy exchanges over maize crops and opens perspectives for better water management of the crop in the future.
Societal cost-benefit analyses based on quantified drought risks to assess Dutch Delta Program investments
Authors: Mens Marjolein , Rhee, van Gigi , Schasfoort Femke , Kielen Neeltje
Published: March 2021

Adaptive policy-making on drought risk management requires integrated assessment of uncertain future developments, policy actions and combinations of those. Preferably, such an assessment is based on quantified drought risks, defined as the integral of drought probability and economic consequences for all relevant sectors impacted by drought. The investment costs of proposed policy measures and strategies (various measures combined) can then be compared with the expected risk reduction.

We developed a method and assessment instrument to explore drought risk in the Netherlands, now and in the future, as well as in response to policy actions. By quantifying the amount of risk reduction in euro’s/year, we were able to assess costs and benefits of the investments proposed by various stakeholders.  The method has been applied in support of the Netherlands drought risk management strategy as part of the National Delta Program which has to prepare the Netherlands for climate change. Drought risks were quantified by carrying out simulations with the National Water Model and coupled impact modules for five water users: agriculture, shipping, drinking water, industry water, and nature areas. A qualitative approach was taken for the drought effects on nature areas.

With the approach taken, we were able to assess costs and benefits of the investment strategy proposed by various stakeholders. The risk reduction of a measure differs per scenario, per year and per combination of measures, while the annual costs are the same. Results showed that the strategy was cost-effective under a scenario with ongoing climate change, in which the combined probability of precipitation deficits and low river flows increases. The method also provided insight into the most opportune time to implement the measures, considering uncertainty about future climate change. This provided relevant input for adaptive policy planning on the national scale.
Machine Learning (Neuronal Net, Random Forest, and C5.0 single decision tree) based on pXRF data as a tool to date sediment layers of the Nile Delta
Authors: Seeliger Martin , Altmeyer Marina , Ginau Andreas , Schiestl Robert , Wunderlich Jürgen
Published: March 2021

This paper presents the application of machine-learning techniques on pXRF data to establish a chronology for sediment cores around Tell Buto (Tell el-Fara´in) in the northwestern Nile Delta. As modern laboratories for dating techniques like OSL or 14C are rare in Egypt and sample export is restricted, we are facing a lack of opportunities to create a robust chronology, which is indispensable in modern Geoarchaeology.

Therefore, we present a new approach to transfer archaeological age information gained at the excavation at Buto to corings of the wider Buto area. Sediments of archaeological outcrops and pits with known age are measured using pXRF to create a geochemical “fingerprint” for several historic eras. Afterwards, these “fingerprints” are transferred to corings of the surrounding areas using machine-learning algorithms.

This paper presents 1) the application of three different machine-learning approaches (Neuronal Net, Random Forest, and C5.0 decision tree) to check if archaeological age information can be transferred to sediments far off the settlement mounds using pXRF data, 2) the comparison of all approaches and the evaluation if the easily anticipated decision tree and Random Forest show similar results as the “black-box system” Neuronal Net, and finally, 3) a case study that provides the results of Altmeyer et al. (in review) for Kom el-Gir, a further settlement mound little north of Buto, with a chronostratigraphic framework based on this approach.

Reference:

Altmeyer, M., Seeliger, M., Ginau, A., Schiestl, R. & J. Wunderlich (in review):  Reconstruction of former channel systems in the northwestern Nile Delta (Egypt) based on corings and electrical resistivity tomography (ERT). (Submitted to E & G Quaternary Science Journal).
Exploring parameter uncertainty in a model of the Antarctic Ice Sheet
Authors: Phipps Steven , Roberts Jason , King Matt
Published: March 2021

Physical processes within ice sheet models are sometimes described by simplified schemes known as parameterisations. The values of the parameters within these schemes can be poorly constrained by theory or observation. Uncertainty in the parameter values translates into uncertainty in the outputs of the models. Proper quantification of the uncertainty in model predictions therefore requires a systematic approach for sampling parameter space. We demonstrate a simple and efficient approach to identify regions of multi-dimensional parameter space that are consistent with observations. Using the Parallel Ice Sheet Model to simulate the present-day state of the Antarctic Ice Sheet, we find that co-dependencies between parameters preclude the identification of a single optimal set of parameter values. Approaches such as large ensemble modelling are therefore required in order to generate model predictions, such as projections of future global sea level rise, that incorporate proper quantification of the uncertainty arising from the parameterisation of physical processes.
Same soil - different climate: crop model inter-comparison with lysimeter data of translocated monoliths
Authors: Groh Jannis , Gerke Horst H. ,   crop-soil modelling initiative
Published: March 2021

Crop model inter-comparisons have mostly been carried out to test the predictive ability under the past range of climatic conditions and for soils of the same site. Unknown is, however, the ability of individual crop models to predict effects of changes in climatic conditions on soil ecosystems beyond the range of site-specific variability. The objective of this study was to test the predictive ability of agro ecosystem models using weighable lysimeter data for the same soil under changed climatic conditions and to compare the simulated crop growth and soil-ecosystem response to climate change between these models. To achieve the objective, data were analyzed from the network of TERENO SOILCan lysimeters for a soil-ecosystem at the original site (Dedelow) and data from the lysimeters containing Dedelow soil monoliths that were transferred to Bad Lauchstädt and Selhausen. For Bad Lauchstädt, this transfer was to a drier and a warmer and for Selhausen to a warmer and wetter site as compared to the original location of the soils at Dedelow. Data time series from the cropped arable soil lysimeters included drier and wetter years and a site-specific crop rotation under comparable management conditions. Identical soil properties and crop growth and boundary conditions were provided for all models after a calibration for the original site at Dedelow, predictions were made for sites Selhausen and Bad Lauchstädt using boundary conditions from those sites. The overall simulation performance of the models was separated in a crop-related part, ecosystem productivity (grain yield, biomass, leaf area index) and in an environmental part, ecosystem fluxes (evapotranspiration, net drainage, soil moisture). When moving soil to a drier region, the crop models’ agronomic and environmental part were well predicted, when moving to wetter regions, only the environmental part of the models seemed to be well predicted. The results suggest considering climate change scenarios, more attention to soil properties and testing of model performance for conditions beyond the calibrated range and site-specific variability will help improving the models.
Analysis of a short-duration severe precipitation event in a small ungauged basin through a semi-distributed hydrological model
Authors: Sarchani Sofia , Tsanis Ioannis
Published: March 2021

A cyclone passed over Western Crete in October 17, 2006 and caused a heavy precipitation event producing a flash flood in a small agricultural basin. The only rain gauge in the studied basin recorded daily rainfall of 196.2 mm with a time-step of 15 minutes while 117 mm was recorded in 4 hours. Simulation of the flow hydrograph was performed with the semi-distributed hydrological model HBV-light and the calibration with the post-flood field data from witnesses that indicated the time to peak flow and the maximum water depth of the passing flood wave. The warming-up period of the model was sixteen days and the previous observed rainfall was 21 mm which was recorded on October 12th. Potential evaporation was estimated through the Blaney-Criddle method. The basin was divided into various elevation zones representing three vegetation classes. The parameters regarding the soil moisture routine were applied per vegetation class. Sensitivity analysis, performed by changing one parameter at a time shows that the parameters concerning the response and routing routine affected mostly the peak hydrograph. Initial results for the peak hydrograph were compared with the one validated with HEC-HMS model and produced a very good Nash-Sutcliffe coefficient. There is on-going research of the effect of HBV-light parameters and further results will appear on the poster.
Tuning standalone setup of Limfjord with CMEMS boundary conditions
Authors: Frishfelds Vilnis , Murawski Jens , She Jun
Published: March 2021

Coastal zones experience huge variability due to combined influence of processes in ocean, atmosphere and land. At the same time, coastal areas are important for economic, social and environmental interests such as shipping, aquaculture and mussel fisheries. Nissum Broad and Lem Vig situated in Limfjord constitute one of the finest Flatoyster environments in Europe. The FORCOAST project of Limfjord area as part of Horizon 2020 research and innovation program is dealing with Copernicus-based downstream information services incorporating CMEMS products, local monitoring data and advanced modelling. Within the FORCOAST project, downstram application for the coastal areas and estuaries of the Limfjord are developed. In this study, the Limfjord domain in about 185m horizontal resolution with wet boundaries at Baltic Sea and the North Sea is considered. Sea level and inflows in Limfjord are largely dependent on boundary conditions at North sea and Baltic sea. Therefore, a tuning of boundary conditions of standalone setup is performed by linear scaling of boundary values. The applied ocean model is the HBM model (HIROMB-BOOS Model) which is also well suited for seemless nesting at various scales enabling to model the transition from the basin-scales to coastal- and estuary-scales. Therefore, the results of standalone setup are compared with two-way nested CMEMS Baltic Monitoring Forecasting Centre set-up with included Limfjord domain. The results show that both tuned standalone setup and nested setups are able to provide high quality sea level forecast for storm surge warning, temperature, salinity and currents. The model is able to handle the shallow thermoclines in summer as well as the strong tidal and wind driven transport through narrow straits in autumn and winter. Tuning of standalone setup enables to reach comparable performance in sea level and thermodynamics as of two-way nested setup at much lower computational cost.
Kleptoplastic foraminifera: a trophic strategy of life 
Authors: Courtial Julia , Metzger Edouard , Lothier Jérémy , Choquel Constance , Limami Anis M. , Cukier Caroline , Geslin Emmanuelle
Published: March 2021

Foraminifera are single-celled organisms, and part of protists. They are present in all types of environments, though most foraminifera are marine benthic and are found from the deep ocean to the intertidal zone. Thus, foraminifera are subjected to various environmental stresses, (natural or anthropogenic). Because of their rapid response to stresses and their strong resistance, foraminifera are studied as paleo-environmental indicators. However, little is currently known about their biology, and specifically their metabolism and physiology. Some foraminifera species are notably known to retain, in their cytoplasm, chloroplasts from diatom preys. This phenomenon is called kleptoplasty. It has been shown that kleptoplasts remain intact and photosynthetically functional from a few days to several weeks, depending of the foraminiferal species and abiotic factors as light. In order to better understand this life strategy and the advantages provided to foraminifera by kleptoplasty in a coastal mudflat environment, we study metabolism of kleptoplastic and non-kleptoplastic species.

The “Mudsurv” (Mudflat survey, OSUNA) project initiated in 2016 a monitoring of the foraminiferal fauna and sediment geochemistry of Bourgneuf Bay (French Atlantic Coast). The main foraminiferal species observed were: Ammonia sp. T6, Elphidium oceanense and a kleptoplastic specie, Haynesina germanica. We therefore set up a monthly monitoring of respiration and photosynthesis of those kleptoplast and non-kleptoplast foraminifera species. The oxygen production or consumption is measured by microelectrodes in light and darkness. Preliminary results suggest a seasonality of photosynthesis in kleptoplast foraminifera. A second approach, using gas chromatography-mass spectrometry (GC-MS)-based experiments, provided us with the first’s foraminifera metabolomes highlighting kleptoplast species metabolic specificities.
Land-use impacts of variable renewable energy in Brazil
Authors: Turkovska Olga , Schmidt Johannes
Published: March 2021

Brazil has seen more than a ten-fold increase in wind power capacity in the last decade and in the past few years, the development of solar PV increased as well. However, little is known about the impacts of variable renewable generation (VRES) in Brazil compared to other world regions, although Brazilian wind power infrastructure is concentrated in the least protected ecosystems that are prone to degradation, desertification and species extinction.  Even less is known about solar PV. This study focuses on land-use impacts of past VRES generation development in Brazilian federal states, which cover most of the country's VRES installed capacity. We assessed and compared their spatial installation patterns associated land-use and land cover change in the period before installation until 2019, using a detailed wind turbine and solar PV location database in combination with a high-resolution land-use and land cover map. Also, we explored which drivers contributed to the existing allocation of VRES in Brazil. We found that 62% of the studied wind park area was covered by native vegetation and coastal sands. Overall, 3.2% of the total wind park area was converted from native vegetation to anthropogenic use. Wind parks installed mainly on native vegetation, on average, underwent higher land-use change compared to other wind parks. Similar to wind power, solar PV in some regions e.g., Bahia, occupied mostly native vegetation land, however being installed in closer proximity to anthropogenic land activities than wind power.
A multi-century spring precipitation history for northern Iran derived from tree-ring δ18O 
Authors: Foroozan Zeynab , Grießinger Jussi , Pourtahmasi Kambiz , Bräuning Achim
Published: March 2021

Knowledge about the long-term hydroclimatic variability is essential to analyze the historic course and recent impact of climate change, especially in semi-arid and arid regions of the world. In this study, we present the first tree-ring δ18O chronology for the semi-arid parts of northern Iran based on juniper trees. We were able to reconstruct past hydroclimatic variability for the past 500 years. The highly significant correlation between tree-ring δ18O and spring precipitation indicates the primary influence of spring moisture availability on δ18O variations. The thereof derived precipitation reconstruction reveals short and long-term variability of precipitation intensity, duration, and frequency of dry/wet events. During the past 500 years, the driest period occurred in the 16th century, whereas the 18th century was comparably wet. A gradual decline in the reconstructed spring precipitation is evident since the beginning of the 19th century, culminating in the continuing drought of the 20th century. An analysis of dry/wet years indicated that over the last three centuries, the occurrence of years with a relatively dry spring is increasing. In contrast, more humid spring conditions are decreasing. However, the overall frequency of the occurrence of extreme events increased over the past five centuries. In addition, past hydrological disasters recorded in Persian history were well represented in our reconstruction. Correlations between our reconstructed precipitation record and large-scale circulation systems revealed no significant influence of large-scale climatic drivers on spring precipitation variations in north Iran, which therefore seem to be mostly controlled by a regional climate forcing.
Progress in modeling streamer and leader discharges­­­
Authors: Ebert Ute , Bouwman Dennis , Francisco Hani , Guo Baohong , Li Xiaoran , Malla Hemaditya , Martinez Andy , Teunissen Jannis
Published: March 2021

We present recent progress in pulsed discharge modeling in Amsterdam that is motivated by high voltage and plasma engineering and by lightning.

We perform streamer simulations with adaptive mesh refinement in 2D and 3D using PIC particle models and fluid models, where we now can include complex electrode shapes and dielectric boundaries. For the longer time evolution, we also have added Ohmic heating, gas expansion, and the relevant ­­­plasma chemistry for air and methane-air mixtures.

Results relevant for lightning physics include

Validation and verification of streamer propagation models (with S. Dijcks and S. Nijdam for the experimental counterpart)

Simulations of streamer branching and comparison with experiments

Parameter studies for long non-branching streamers that can accelerate or decelerate, and vary largely in velocity, radius and inner electron density, depending on the electric field

Different stagnation behavior of positive and negative streamers in low electric fields

Positive streamers in air that can continue to propagate as isolated patches of positive charge, without a conducting channel behind the streamer head

Repetitive discharges, heating, and plasma-chemistry
Constraining the Eurasian biogenic boreal carbon-cycle with satellite-SIF
Authors: Schreiner Lena , Grossmann Katja , Butz André , Vardag Sanam N. , Schömann Eva-Marie
Published: March 2021

The Eurasian boreal ecosystem acts as a major terrestrial carbon sink in the northern hemisphere. Under changing climatic conditions, it is crucial to monitor biogenic carbon fluxes in this area. The Siberian in-situ CO2 data are, however, sparse in spatial coverage and limit model-validation there. Satellite observations of CO2 and Sun-Induced Fluorescence (SIF) can provide essential information to constrain the Eurasian boreal biogenic carbon-cycle and further, to improve carbon cycle inverse models.

In this study, we investigate the Eurasian boreal carbon cycle with satellite observations of the Orbiting Carbon Observatory 2 (OCO-2) and the Greenhouse gase Observing SATellite (GOSAT). We compare the observed carbon cycle dynamics to model data such as provided by CarbonTracker (CT2019, CT-NRT.v2020-1) and find differences in the ppm range. Various sensitivity studies with respect to region selection, sampling biases and model choices are used to consolidate the robustness of the detected pattern. Using SIF and FLUXCOM GPP data, we will show first attempts to attribute the model-measurement differences to uncertainties in biogenic carbon fluxes.
Evaluation of high-resolution meteorological global data products using flux tower observations across Brazil
Authors: Brown Jamie , Rosolem Rafael , Woods Ross , Rocha Humberto , Roberti Debora
Published: March 2021

In the past decade, the scientific community has seen an increase in the number of global hydrometeorological products. This has been possible with efforts to push global hydrological and land surface modelling to hyper-resolution applications. As the resolution of these datasets increase, so does the need to compare their estimates against local in-situ measurements. This is particularly important for Brazil, whose large continental scale domain results in a wide range of climate and biomes. In this study, high-resolution (0.1-0.25 deg) global and regional meteorological datasets are compared against flux tower observations at 11 sites across Brazil (for periods between 1999-2010), covering Brazil’s main land cover types (tropical rainforest, woodland savanna, various croplands, and tropical dry forests) to assess the quality of four global reanalysis products [ERA5-Land, GLDAS2.0, GLDAS2.1, and MSWEPv2.2] and one regional gridded dataset developed from local interpolation of meteorological variables across the country [Brazilian National  Meteorological Database (referred here as Xavier)]. Whilst the only measured variable for MSWEP was precipitation, all other gridded datasets also included surface meteorological variables such as air temperature, wind speed, pressure, downward shortwave and longwave radiation, and specific humidity. Data products were evaluated for their ability to reproduce the daily and monthly meteorological observations at flux towers. A ranking system for data products was developed based on the mean squared error. To identify the possible causes for these errors further analysis was undertaken to determine the contributions of correlation, bias, and variation to the MSE. Results show that, for precipitation, MSWEP outperforms the other datasets at daily scales but at a monthly scale XAVIER performs best. For all other variables, ERA5-Land achieved the best ranking (smallest) errors at the daily scale and averaged the best rank for all variables at the monthly scale. GLDAS2.0 performed least well at both temporal scales, however the newer version (GLDAS2.1) was an improvement of its older version for almost every variable. Xavier wind speed and GLDAS2.0 solar radiation outperformed the other datasets at a monthly scale. The largest contribution to the MSE at the daily scale for all datasets and variables was the correlation contribution whilst at the monthly scale it was the bias contribution. ERA5-Land is recommended when using multiple hydro-meteorological variables to force land-surface models within Brazil.
EPOS-Norway Portal
Authors: Michalek Jan , Atakan Kuvvet , Rønnevik Christian , Indrøy Helga , Ottemøller Lars , Natvik Øyvind , Langeland Tor , Lampe Ove Daae , Fonnes Gro , Cook Jeremy , Christensen Jon Magnus , Baadshaug Ulf , Kierulf Halfdan Pascal , Grøtan Bjørn-Ove , Olesen Odleiv , Dehls John , Maupin Valerie
Published: March 2021

The European Plate Observing System (EPOS) is a European project about building a pan-European infrastructure for accessing solid Earth science data, governed now by EPOS ERIC (European Research Infrastructure Consortium). The EPOS-Norway project (EPOS-N; RCN-Infrastructure Programme - Project no. 245763) is a Norwegian project funded by National Research Council. The aim of the Norwegian EPOS e‑infrastructure is to integrate data from the seismological and geodetic networks, as well as the data from the geological and geophysical data repositories. Among the six EPOS-N project partners, four institutions are providing data – University of Bergen (UIB), - Norwegian Mapping Authority (NMA), Geological Survey of Norway (NGU) and NORSAR.

In this contribution, we present the EPOS-Norway Portal as an online, open access, interactive tool, allowing visual analysis of multidimensional data. It supports maps and 2D plots with linked visualizations. Currently access is provided to more than 300 datasets (18 web services, 288 map layers and 14 static datasets) from four subdomains of Earth science in Norway. New datasets are planned to be integrated in the future. EPOS-N Portal can access remote datasets via web services like FDSNWS for seismological data and OGC services for geological and geophysical data (e.g. WMS). Standalone datasets are available through preloaded data files. Users can also simply add another WMS server or upload their own dataset for visualization and comparison with other datasets. This portal provides unique way (first of its kind in Norway) for exploration of various geoscientific datasets in one common interface. One of the key aspects is quick simultaneous visual inspection of data from various disciplines and test of scientific or geohazard related hypothesis. One of such examples can be spatio-temporal correlation of earthquakes (1980 until now) with existing critical infrastructures (e.g. pipelines), geological structures, submarine landslides or unstable slopes.  

The EPOS-N Portal is implemented by adapting Enlighten-web, a server-client program developed by NORCE. Enlighten-web facilitates interactive visual analysis of large multidimensional data sets, and supports interactive mapping of millions of points. The Enlighten-web client runs inside a web browser. An important element in the Enlighten-web functionality is brushing and linking, which is useful for exploring complex data sets to discover correlations and interesting properties hidden in the data. The views are linked to each other, so that highlighting a subset in one view automatically leads to the corresponding subsets being highlighted in all other linked views.
A peek into Jupiter’s normal modes from Juno gravity data
Authors: Durante Daniele , Iess Luciano
Published: March 2021

As of April 2021, Juno is close to complete its nominal mission, awaiting to enter its extended mission. Thanks to the extremely accurate Doppler data (having an accuracy as low as 10 micron/s at an integration time of 60 s) acquired during close perijove passes in the last 4 years, Juno provided an unprecedented view of Jupiter’s gravity field, which is crucial to determine its interior structure. In order to recover the gravity field of the planet, the orbits of Juno have to be reconstructed to a very high accuracy. The latest gravity field reconstruction showed hints to a non-static and/or non-axially symmetric field, possibly related to several different phenomena, such as normal modes, localized atmospheric or deeply-rooted dynamics. These tiny phenomena produces a residual signal at a level of few tens of micron/s in Juno Doppler data. To confidently study these tiny unconventional phenomena, the dynamical model of Juno’s spacecraft have been accurately characterized and possible error sources investigated and ruled out.

The focus of this study is Jupiter’s normal modes. Our main goal is to assess whether the residuals signatures can be explained by the gravitational disturbances induced by normal modes inside the planet, assuming reasonable physical constraints. Ground-based observations of Jupiter’ normal modes can be used as a guide.
Ultra-high resolution assessment of potential impacts of vegetation shadows on satellite-derived spectral signals from small thermokarst lakes in the boreal forest-tundra transition zone (subarctic Canada)
Authors: Freitas Pedro , Vieira Gonçalo , Mora Carla , Canário João , Folhas Diogo , Vincent Warwick F.
Published: March 2021

Warming of the circumpolar north is accelerating permafrost thaw, with implications for landscapes, hydrology, ecosystems and the global carbon cycle. In subarctic Canada, abrupt permafrost thaw is creating widespread thermokarst lakes. Little attention has been given to small waterbodies with area less than 10,000 m2, yet these are biogeochemically more active than larger lakes. Additionally, the landscapes where they develop show intense shrubification and terrestrialization processes, with increases in area and height of shrub and tree communities. Tall vegetation that is colonizing waterbody margins can cast shadows that impact productivity, thermal regime and the water spectral signal, which in satellite data generates pixels with mixed signatures between sunlit and shaded surfaces. We undertook UAV surveys using optical and multispectral sensors at long-term monitoring sites of the Center for Northern Studies (CEN) in subarctic Canada, from the sporadic (SAS/KWAK) to the discontinuous (BGR) permafrost zones in the boreal forest-tundra transition zone. This ultra-high spatial resolution data enabled spectral characterization and 3D reconstruction of the study areas. Ultra-high resolution digital surface models were produced to model shadowing at satellite overpass time (WorldView, PlanetScope and Sentinel-2). We then analyzed the impacts of surrounding vegetation and cast shadows on lake surface spectral reflectance derived from satellite imagery. Ultra-high resolution UAV data allows generating accurate shadow models and can be used to improve the assessment of errors and accuracy of satellite data analysis. Particularly, we identify different spectral signal impacts of cast shadows according to lake color, which highlight the need for special attention of this issue onto lakes with more turbidity.

This research is funded by the Portuguese Foundation for Science and Technology (FCT) under the project THAWPOND (PROPOLAR), by the Centre of Geographical Studies (FCT I.P. UIDB/00295/2020 and UIDP/00295/2020), with additional support from ArcticNet (NCE), Sentinel North (CFREF) and CEN and is a contribution to T-MOSAiC. PF is funded by FCT (SFRH/BD/145278/2019).
Detectability of biosignatures on LHS 1140 b
Authors: Wunderlich Fabian , Scheucher Markus , Grenfell John Lee , Schreier Franz , Sousa-Silva Clara , Godolt Mareike , Rauer Heike
Published: March 2021

Rocky extrasolar planets orbiting M dwarfs are prime targets in the search for habitable surface conditions and biosignatures with near-future telescopes like the James Webb Space Telescope (JWST) and the Extremely Large Telescope (ELT). Even for the closest known targets the capabilities to characterize Earth-like or CO2-dominated atmospheres with JWST or ELT might still be limited to a few molecules such as CO2 or CH4. Hence it would be difficult to draw conclusions on the surface conditions and potential habitability of these planets. In clear H2-He atmospheres the molecular features in transmission spectra could be much larger and hence potential biosignatures might be detectable.

In this study, we investigate the detectability of the potential biosignatures NH3, PH3, CH3Cl, and N2O, assuming different H2-He atmospheres for the habitable zone super-Earth LHS 1140 b. Recent observations of the atmosphere of LHS 1140 b suggest that the planet might hold a clear H2-dominated atmosphere and might show an absorption feature around 1.4 µm due to H2O or CH4 absorption. Here we use the coupled convective-climate-photochemistry model 1D-TERRA to simulate H2 atmospheres of LHS 1140 b with different amounts of CH4 and assuming that the planet has an ocean and a biosphere.

The destruction of the potential biosignatures NH3, PH3, CH3Cl, and N2O shows a weak dependence on the concentrations of CH4. For weak abundances of CH4 only 5 to 10 transits are required to detect these molecules with JWST or ELT. However, for CH4 surface mixing ratios of a few percent only NH3 and N2O might be detectable with less than 10 transits. A scenario with large abundances of CH4 is consistent with the spectral feature at 1.4 µm and such an atmosphere might allow habitable surface temperatures. If this spectral feature at 1.4 µm originates from H2O absorption, the planet is likely not habitable at the surface.
Laboratory evaluation of water vapour concentration dependence of commercial water vapour isotope cavity ring-down spectrometers for continuous onsite atmospheric measurements in the Amazon rainforest
Authors: Komiya Shujiro , Kondo Fumiyoshi , Moossen Heiko , Seifert Thomas , Schultz Uwe , Geilmann Heike , Walter David , Lavric Jost
Published: March 2021

Commercially available laser-based spectrometers permit continuous field measurements of water vapour (H2O) stable isotope compositions, yet continuous observations in the Amazon, a region that significantly influences atmospheric hydrological cycles on regional to global scales, are largely missing. In order to achieve accurate on-site observations in such conditions, these instruments will require regular on-site calibration, including for H2O concentration dependence ([H2O]-dependence) of isotopic accuracy.

With the aim of conducting accurate continuous δ18O and δ2H on-site observation in the Amazon rainforest, we conducted a laboratory experiment to investigate the performance and determine the optimal [H2O]-dependence calibration strategy for two commercial cavity-ring down (CRDS) analysers (L1102i and L2130i models, Picarro, Inc., USA), coupled to our custom-built automated calibration unit. We particularly focused on the rarely investigated performance of the instruments at atmospheric H2O contents above 35,000 ppm, a value regularly reached at our site.

The later analyser model (L2130i) had better precision and accuracy of δ18O and δ2H measurements with a less pronounced [H2O]-dependence compared to the older L1102i. The [H2O]-dependence calibration uncertainties did not significantly change with calibration intervals from 28 h up to 196 h, suggesting that one [H2O]-dependence calibration per week for the L2130i and L1102i analysers is enough. This study shows that with both CRDS analysers, correctly calibrated, we should be able to discriminate natural diel, seasonal and interannual signals of stable water vapour isotopes in a tropical rainforest environment.

 
Evaluation of surface runoff model hypothesis by multi-objective calibration using discharge and sediment data
Authors: de Lavenne Alban , Lindström Göran , Strömqvist Johan , Pers Charlotta , Bartosova Alena , Arheimer Berit
Published: March 2021

Conceptual hydrological models can move towards process-oriented modelling when addressing broader issues than flow modelling alone. For instance, water quality modelling generally requires understanding of pathways and travel times. However, conceptual modelling often relies on a calibration procedure of discharge at the outlet, which aggregates all processes at the catchment scale. As the number of parameters increases, such an approach can lead to model over-parametrisation issues. In this study we tested if adding a second kind of observation, specifically sediment data, can help distinguish surface runoff from total discharge. This new constraint relies on a hypothesis that in stream sediment concentrations are strongly influenced by surface runoff (through erosion and remobilisation). We tested our hypothesis by applying a multi-objective calibration (simulation performance on discharge and suspended sediment) to the World-Wide HYPE hydrological model (WWH) and we used this framework to evaluate new surface flow modelling routines. We gathered data for 111 catchments spread over the USA where both discharge and sediment observation were available at a daily step at locations suitable for WWH. 

Results show that in comparison to a single-objective calibration on discharge this multi-objective calibration enables a significant improvement on the simulation performance of suspended sediments without a significant impact on the performance of discharge. This illustrates the benefits of multi-objective calibration rather than using two calibrations made one after the other. In addition, this evaluation framework highlights the advantage of a new process description for surface runoff in the WWH model that relates soil moisture conditions to surface runoff ratio. The new surface runoff routine resulted in similar discharge performances as the original one but with fewer parameters, which reduce equifinality and can prevent inadequate model complexity in data-poor areas. 
Holocene reconstruction of plant communities and impacts of human activity from sedaDNA in the Austrian Alps.
Authors: Zetter Scarlett , Garcés Pastor Sandra , Lammers Youri , Tribsch Andreas , Brown Antony G. , Coissac Eric , Lavergne Sébastian , Heintzman Peter D. , Alsos Inger G.
Published: March 2021

The Alps contain highly biodiverse ecosystems including a large number endemic flora. As a result of climate change and anthropogenic activities, such ecosystems are at risk from upward vegetation displacement and species loss. Extensive archaeological research in the Eastern Alps has documented human settlement from ~5500 years ago driven by salt and copper mining; which has caused significant impact on the ecosystems through mining, deforestation, and pastoral farming. To elucidate the effects of climate change and anthropogenic activities on plant biodiversity, multi-proxy reconstructions have been carried out throughout the Western Alps . Despite this research, the palaeoecological history of the Eastern Alps is relatively understudied. Consequently, we are limited in our understanding of how climate change and human impact have affected past biodiversity and the formation of the contemporary vegetation in this region. Here, we focus on the Austrian sub-alpine lake, Großer Winterleitensee located at the Easternmost margin of the Alps; only locally glaciated during the Pleistocene. We applied sedimentary ancient DNA (sedaDNA) metabarcoding to reconstruct Holocene plant community dynamics within the lake catchment. These data, in conjunction with local temperature reconstructions, sediment elemental composition, magnetic susceptibility, and loss-on-ignition analyses, allowed us to identify key intervals of plant diversity change. Two such intervals begin at samples dated ~5500 cal. yr BP and ~2200 cal. yr BP, coinciding with Neolithic and Iron Age settlement phases in the area. Palaeoecological reconstructions of plant biodiversity and their responses to climate change and anthropogenic pressures may be able to provide essential information for future conservation purposes.

 

 

 
Projecting thermal stratification and hypolimnetic oxygen conditions by coupling paleolimnological and 1D lake model approaches
Authors: Jenny Jean-Philippe , Itier Olivia , Frossard Victor , Etienne David , Guillard Jean
Published: March 2021

Climate change raises many questions about the future of lakes’ thermal regime and hypolimnetic oxygen conditions. One dimensional models have been widely implemented over that last years 1–3, but most of these models are calibrated against very few years of limnological records, potentially limiting the robustness in long-term reconstructions and preventing inclusion of future scenarios. To analysis the variability and the effects of climate change on thermal regime and oxygen conditions of deep hard-water lakes, we relayed on paleolimnological records and 1D thermal lake model calibrated against time series of limnological data collected by the French Observatoire des LAcs (OLA). Continuous sediment records on four peri-alpine lakes (Lake Geneva, Lake Annecy, Lake Bourget and Lake Aiguebelette) were analysed using micro-XRF Mn-Fe ratio as proxy to infer near-annual trends of oxygen conditions for the past 300 years4. Past hypoxia dynamics were further inferred from varved records preserved in sediment cores5. General Lake Model (GLM), i.e. a 1-D modelling tool, has been constrained by climate data derived from meteorological observations and CMIP6 simulations in order to reconstruct and forcast stratification regims for the next century. Our paleolimnological results show that fluctuations in hypoxic volumes since the 1950s were great and that these fluctuations were essentially driven by climatic factors, legitimating the use of thermal model approaches for future projections of hypolimnetic oxygen conditions. In this line, thermal regime simulations based on GLM forecast an intensification in thermal stratification and an increase in volumes of water warmer than 9°C over the period 1850-2100 with potential consequence for hypolimnetic oxygen conditions and ecological habitats. Coupling model and paleolimnological approaches seem a promising way to examine the evolution of lakes in the past, and to realistically anticipate the future of lakes for the next decades.