bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of change for the mineral Exploration - INFACT project
Authors: MacCallum Cathryn , Russill Jon , Kirsch Moritz , Ajjabou Leila , Salam Insiya , Bennet Louis
Published: March 2020

The INFACT project aims to reinvigorate mineral exploration in Europe by engaging society and using new technology and research to improve mineral exploration practice. The consortium is formed of geo- and social scientists working together to achieve a new vision of mineral exploration. As a key part of INFACT, expert stakeholders from across Europe and other jurisdictions such as Australia and Canada have been engaged in a series of online and face to face discussions to determine and address identified challenges to exploration and a way to overcome them. 

Five key environmental and social challenges and barriers to exploration in Europe have been determined by INFACT through a mix of qualitative and quantitative research. These were (i) existing land use, (ii) the cost of mineral exploration, (iii) public perceptions and negative attitudes toward the exploration and mining industry, (iv) sustainability and the environment, and (v) governance and regulatory structures and processes. 

Through a series of workshops and interviews, discussing ways to address these challenges and barriers, a vision for mineral exploration and mining in Europe was created:

Mining in Europe should contribute to local and regional sustainable development, enabling a low carbon economy through environmentally and socially acceptable extraction of critical raw materials(CRM). This will involve:

The European Commission developing and enforcing rigorous and binding legislation with respect to all mineral exploration activities;

Increased investment contribution for exploration of CRM within Europe;

Exploration companies being required to adopt environmental and socially acceptable good practice;

Increased awareness of the importance of mining to support a low carbon economy and improved public trust in the process;

Creation of socio-economic shared value through adoption of multi-stakeholder collaborative planning and visioning; and

Exploration companies achieving and maintaining a Social Licence to Operate;

The work presented will determine a way to ensure socio-environmentally sustainable supply of raw materials and the key steps required to achieve this vision. 
Correcting position error in rainfall estimates using temporal and spatial warping
Authors: Le Coz Camille , Heemink Arnold , Verlaan Martin , ten Veldhuis Marie-claire , van de Giesen Nick
Published: March 2020

An increasing number of satellite-based rainfall estimates, with ever finer resolution, are becoming available. They are particularly valuable in regions with sparse radar and gauge networks. For example, in most of sub-Saharan Africa, the gauge network is not dense enough to represent the high variability of the rainfall during the monsoon season. However, satellite-based estimates can be subject to errors in position and/or timing of the rainfall events, in addition to errors in the intensity.
Many satellite-based estimates use gauge measurements for bias correction. Bias correction methods focus on the intensity errors, and do not correct the position error explicitly. We propose to gauge-adjust the satellite-based estimates with respect to the position and time. We investigate two approaches: spatial and temporal warping. The first one is based on a spatial mapping and correct the spatial position while keeping the time constant. The second uses a temporal mapping and keeps the spatial domain unchanged. The mappings are derived through a fully automatic registration method. That is, only the gauge and satellite-based estimates are needed as inputs. There is no need to manually predefine the rain features.
The spatial and temporal approaches are both applied to a rainfall event during the monsoon season in southern Ghana. The Trans-African Hydro-Meteorological Observatory (TAHMO) gauge network is used to gauge-adjust the IMERG-Late (Integrated Multi-Satellite Retrievals for GPM) satellite-based estimates. The two approaches are evaluated with respect to the timing, the location and the intensity of the rainfall event.
Dilation and flow resistance of granular flows in a rotating drum
Authors: Kaitna Roland , Shuai Li , Taylor-Noonan Alexander , Take William Andrew , McArdell Brian , McElwaine James , Bowmann Elisabeth
Published: March 2020

The flow resistance in granular mass flows can be due to frictional contacts or collisional interactions between particles. For a constant number of particles, the transition from a frictional to a collisional regime is expected to depend on flow velocity and is associated with an increase of volume and a decrease of bulk density, an effect termed dilation. The relation between velocity, dilation and flow resistance is not well understood. Here we present results of steady, non-uniform flows of ceramic beads (d = 4 mm) in a rotating drum, a setup allowing observations and averaging of parameters measured over an extended period of time. We systematically varied flow mass between 12.3 and 49 kg and flow velocity between 0.2 and 1.2 m/s, while continuously measuring basal normal stress and flow depth. Flow resistance was assessed by calculating average bulk shear stress from torque measurements at the axis of the drum as well as from the deviation of the center of mass from the vertical. Additionally, the flows were captured by high-speed video recordings through the transparent side wall. We find bulk densities at the deepest section of the flow decreasing from 1430 kg/m³ at low velocities to 1370 kg/m³ at the highest velocity for the largest flow mass. At the same time flow resistance increased linearly. When the flow mass was reduced, also bulk density decreased, indicating the importance of overburden pressure for dilation. Video recordings revealed that shear is concentrated in depth zones of lower volume fraction. Our results shall contribute to a better understanding of the transition from a frictional to a collisional flow regime and may help to assess the importance of dilation for gravitational mass flows.
Can non-asbestiform amphibole fibers trigger carcinogenesis mechanisms?
Authors: Militello Gaia M. , Gaggero Laura , Sanguineti Elisa , Yus González Adrián , La Maestra Sebastiano
Published: March 2020

Minerals defined as asbestos include only the fibrous varieties (length > 5 µm, diameter < 3 µm and length/diameter ratio > 3:1) and asbestiform (high tensile strength or flexibility) of serpentine and amphibole.

However, there are also prismatic varieties of amphiboles, which despite the same chemical composition, are not classified as asbestos. Their geometric ratio would fall within the concept of fiber, but the minerals are not asbestiform.

Starting from a fairly contradictory context, the goal of this work was to analyze the variables inherent the morphological, but above all, the clastogenic effect determined by exposure of both asbestiform and non-asbestiform amphiboles.

The asbestiform fibers (F3), and the other three samples containing non-asbestiform amphiboles (P1, P2, P3) were tested in A549 cells line. Each sample of fiber was inoculated in A549 cells at a concentration of 100 µg/ml for 48h. Experiments were assayed in triplicate and repeated twice. To evaluate the micronuclei number for each sample the fixed cells were dropped onto clean microscope slides, stained and observed by optical microscopy at 100X.

Obtained results showed a statistically significant increase (P < 0.05) of micronuclei in F3 exposed cells when compared to negative controls. Similar results were reported when A549 cells were exposed with non-asbestiform amphiboles P2. No significant increase of micronucleated cells was observed after exposure of cells line at samples P1 and P3.

Moreover, to investigate the effect long-term triggered after 24h post fiber exposure of the medium inoculated cells were replaced with fresh culture medium and the cultures were grown for 72h. Albeit a prolonged contact of the F3 and P3 fibers resulted in a statistically significant increase (P < 0.01) of the micronuclei, no increase was reported for P2.

These results indicate that the contact of non-asbestiform amphiboles in vitro, can determine a genetic disorder, a necessary step in the cancer development. However, the kinematic of processes and the bearing of results are to be further clarified. For this purpose, the same starting materials are presently tested to determinate the transformation efficiency in no-tumoral cells and will be analyzed the different pathway involved in the etiopathogeneses of diseases trigger by inhalation of fiber.
Changes in braided river morphology driven by flood sequencing
Authors: Fernandez Rocio Luz , Parsons Daniel , McLelland Stuart , Bodewes Bas
Published: March 2020

Sequential observations of channel adjustments in relation to short-term flow variability are required to evaluate the effects of temporal ordering of hydrologic events on channel form. With the increasing hydroclimate variability due to global climate change, fluvial morphology might also exhibit adjustments toward changing equilibria. By combining flume and numerical modelling we examine the mechanism of bed morphology changes of braided rivers to a sequence of low to moderate magnitude flood events. Over 60 runs were performed in a mobile bed flume (10 m x 2.5 m), with constant longitudinal slope (0.015) and mean grain size (0.45 mm) in the Total Environment Simulator at the University of Hull, UK. The outcomes of each run were characterized by a detailed digital elevation model, digital imagery and continuous monitoring of the sediment transported through the flume outlet. Sediment conditions included floods with equilibrium and deficit loads. Rivers were allowed to evolve from an initially flat-bed to a self-organized, steady state. The rate of change and rate of bed load movement against time were indicative of the gradual approach to equilibrium. The Delft3D code in depth-averaged (2-D) mode was used to reproduce different aspects of the braiding process over an up-scaling of the laboratory river. Data analysis allowed us to assess the effect of discharge variation on the braiding dynamics and on the width-to-depth ratio of channels, which although variable in time, fluctuated among defined values. Once in equilibrium, net changes in reach-averaged width and depth values were relatively minor. The adjustment of the river morphology through time was well fitted by an exponential decay expression, and we tested diffusive relationships held within our braided river system for both constant and varying discharge conditions. In long term process-response systems, climatic changes introduce sequences of disruption of equilibria such as those analysed in this study. The results might provide then a useful basis for analysing the similar but more complex long-term dynamics found in natural rivers.

 
Social Acceptance of Small-Scale Hydropower in Austria from 2015 to 2019
Authors: Sposato Robert , Hampl Nina
Published: March 2020

The research presented here is based on an extensive data set of five distinct nationally representative surveys in Austria sampling an average of 1.008 respondents per year. The surveys ran from 2015 to 2019 and were designed to measure respondents’ perceptions and attitudes towards various renewable energy-related issues, including perceptions of and attitudes towards electric vehicles and photovoltaic panels for private consumers but also renewable energy technologies in general and renewable energy production sites, specifically wind turbines, large-scale photovoltaic power plants and small-scale hydropower. Particular attention was paid to the question of local acceptance, or better, support for infrastructure in respondents’ local community. The data presented will thus offer a variety of perspectives. Firstly, longitudinal trends in the acceptance of small-scale hydropower will indicate the relative development of small-scale hydropower in terms of both regional differences but equally with respect to the two other surveyed renewable energy technologies. Comparisons on an aggregate level also offer an in depth and robust multiple regression analysis of the various predictors of social acceptance. Again, comparing these results to the results for both wind and photovoltaic energy technology. From an applied perspective, results are then discussed with respect to their implications for future renewable energy technology scenarios with respect to social acceptance and the role small-scale hydro power can play in these. Equally the rather novel scholarly effort to investigate social acceptance of small-scale hydropower and the potential for comparisons with more extensively studied renewable energy technology forms will offer an interesting ground for debate among academics and practitioners.
Flood recurrence under climate change: a probabilistic flood risk assessment of critical infrastructure in the Danube basin
Authors: Wortmann Michel , Schröter Kai
Published: March 2020

Consistent information on fluvial flood risks in large river basins is typically sparse. This is especially true for the Danube River basin covering up to 14 countries and creating a patchwork of flood risk information across a populous and flood-prone region. As climatic changes have shown to increase flooding in the future, consistent basin-scale assessments prove vital to the insurance industry as well as municipal and infrastructural planning. The Future Danube Model (FDM) was designed to fill this gap complying to both insurance industry and climate science standards. That is, allowing for a reasonably detailed model scale (based on a 25m digital elevation model), stochastic sampling to create a large number of extreme events and flood event footprints (10k years), a thorough calibration and validation as well as the use of an ensemble of climate model output to drive the model under scenario conditions. The model is here used to assess the impact on critical infrastructure across the basin. Results indicate a marked increase in flood risk has already occurred when comparing the current climate period (2006-2035) to the reference period (1970-1999). Further increases are projected under a moderate and a business as usual scenario for the next climate period (2020-2049) and the end of the century (2070-2099). In large parts of the basin, the historical 100-year flood level, often used as a critical protection level for infrastructure, is projected to be equalled or exceeded every 50–10 years, while areas with a 100-year flood risk are projected to increase by 6-19%.
Giant aerosols increase precipitation in marine cumulus and stratocumulus clouds
Authors: Dziekan Piotr , Jensen Jorgen , Grabowski Wojciech , Pawłowska Hanna
Published: March 2020

Sea-salt aerosols with radii exceeding 1 μm have been observed over the oceans. Cloud droplets formed on these giant aerosols can quickly grow to drizzle sizes through condensation of water vapor. Therefore giant aerosols, although not numerous, have been speculated to increase the amount of precipitation produced in clouds. Testing this hypothesis in LES simulations has been difficult, because Eulerian microphysics models are not well suited to model growth of droplets on giant aerosols. On the contrary, Lagrangian microphysics models, which are an emerging alternative to the Eulerian bin microphysics models, can model giant aerosols in a straightforward manner.

LES simulations performed using the University of Warsaw Lagrangian Cloud Model (UWLCM) will be presented. In UWLCM, the Lagrangian super-droplet microphysics model is used. We will assess how giant aerosols affect precipitation formation in marine cumulus (setup based on the RICO campaign) and stratocumulus clouds (setup based on the research flight 2 of the DYCOMS campaign). It will be discussed how the impact of giant aerosols changes with the concentrations of giant and regular aerosols. The results are of importance also for cloud seeding experiments, in which giant sea-salt aerosols can be released into a cloud.
Fast and efficient MPM solver for strain localization problems
Authors: Guerin Antoine , Wyser Emmanuel , Podladchikov Yury , Jaboyedoff Michel
Published: March 2020

Strain localization problems, i.e., shearbandings, have received a lot of interest, especially when strain softening is disregarded from the elasto-plastic consistution relationship. Indeed, reproducing correctly oriented shear bands without softening allows to overcome the mesh-depenency problem. Our work focuses on a Material Point Method (MPM) implementation of strain localization to i) study the behavior of shear bands in order to ii) assess the capabilities of this quite recent numerical method.

To study strain localization and shear banding, we developped an efficient numercial Material Point Method (MPM) solver in Matlab, based on the Update Stress Last (USL) scheme enriched with the Generalized Interpolation Material Point (GIMP) variant, which fixes a major flaw of any MPM solver: the cell-crossing error due to discontinuous gradient of the basis functions. This home-made solver allows us to study strain localizations in either a fixed or continuously deforming continuum. The algorithm solves explicitly momentum equations in an updated lagrangian manner similarly to an explicit FEM solver. We therefore investigate the compression of an elasto-plastic domain under pure shear condition, thus reproducing the geometrical settings and pure shear conditions used in Duretz et al. (2018). Strain softening is disregarded since we do not want any mesh dependence within the solver. A Mohr-Coulomb yield criterion was selected and plasticity was computed by a return mapping algorithm, i.e., we did not use consistent tangent operator. Localization is triggered by a weaker circular inculsion in the center of the domain..

Preliminary results demonstrates the suitability of the MPM solver to reproduce the correct shearbanding behavior under compression, for both static and dynamic meshes. The higher the resolution, the more accurate are the shear bands. Naturally, this implies future implementations of the solver in a GPU-accelerated environment to increase the numerical resolution.
Comparison of spatio-temporal evolution of extreme precipitation events between two high-resolution models in a northern Europe case study
Authors: Thomassen Emma D. , Kendon Elisabeth , Sørup Hjalte J. D. , Chan Steven , Langen Peter L. , Christensen Ole B. , Arnbjerg-Nielsen Karsten
Published: March 2020

Convection Permitting Models (CPM) are believed to improve the representation of precipitation extremes at sub-daily scale compared to coarser spatial scale Regional Climate Models (RCM). This study seeks to compare how the spatio-temporal characteristics of precipitation extremes differ between a 2.2km CPM and a 12km RCM from the UK Met Office with a pan-European domain.

Storm data have been re-gridded to a common 12km grid and all events in the period from 1999-2008 are tracked with the DYMECS tracking algorithm. A peak-over-threshold method is used to sample extreme events within a northern European case area. Maximum intensity and maximum area of extremes are sampled based on the maximum intensity and maximum size reached within their lifetime. Evolution in size and intensity, track patterns, and seasonal occurrence of extreme events are compared between the two models.

For the top 1000 extreme events with the highest maximum intensities, the two models show disagreement in movement direction and spatial and temporal occurrence. While the CPM data are dominated by south-north moving events occurring in summer over central Europe, the RCM data are dominated by west-east moving events occurring over UK and more uniformly distribution over the year. The CPM and RCM however show good agreement in these variables for extreme events instead selected based on largest spatial area. A comparison with the COSMO REA6 reanalysis model continuously nudged towards observations indicates a similar spatial and seasonal distribution of extreme events sampled by maximum intensity as in the CPM. Analysis of the evolution of storms over their lifetime shows on average higher intensities and spatial areas of the most intense storms in the RCM data compared to the most intense storms in the CPM data. Sampling of maximum intensity extreme events in each of the four seasons show larger disagreement between the two models in the evolution in intensity and size in autumn (SON) and winter (DJF) than in spring (MAM) and summer (JJA).
Multi-model data assimilation techniques for flood forecasts
Authors: Matthews Gwyneth , Cloke Hannah , Dance Sarah , Prudhomme Christel
Published: March 2020

Floods are the most common and disastrous natural hazards and due to climate change and socio-economic growth they are becoming more dangerous. Early warning systems are one of the best ways to decrease the effect of floods by increasing preparedness. The European Flood Awareness System (EFAS), part of the European Commission's Copernicus Emergency Management Service, provides medium-range ensemble flood forecasts for the whole of Europe but only calibrates its forecasts locally at river gauge stations where sufficiently long and reliable observations are available. These corrections do not consider the natural relationships that occur between points up and downstream. In this PhD project, data assimilation techniques will be used, in post-processing, to combine the available gauge observations with the forecasts. Using a weighting matrix, the influence of the observations will be extended along the river channel network, taking account of the ensemble and observation uncertainty. EFAS uses meteorological forcings from four numerical weather prediction (NWP) systems, so a multi-model approach will need to be developed.  This requires new data assimilation theory and hydrological process knowledge to ensure consistent updates. Delocalising calibrations will improve the accuracy of forecasts at unobserved locations allowing end-users to make more informed decisions to mitigate flood damage.
Using and acquiring time-series data with the EMSO ERIC DataLab
Authors: Bardaji Raul , Piera Jaume , Dañobeitia Juanjo , Rodero Ivan
Published: March 2020

In marine sciences, the way in which many research groups work is changing as scientists use published data to complement their field campaign data online, thanks to the large increase in the number of open access observations. Many institutions are making great efforts to provide the data following FAIR principles (findability, accessibility, interoperability, and reusability) and are bringing together interdisciplinary teams of data scientists and data engineers.

There are different platforms for downloading marine and oceanographic data and many libraries to analyze data. However, the reality is that scientists continue to have difficulty finding the data they need. On many occasions, data platforms provide information about the metadata, but they do not show any underlying graph of the data that can be downloaded. Sometimes, scientists cannot download only the data parameters of interest and have to download huge amounts of data with other not useful parameters for their studies. On other occasions, the platform allows to download the data parameters of interest but offers the time-series data as many files, and it is the scientist who has to join the pieces of data into a single dataset to be analyzed correctly. EMSO ERIC is developing a data service that helps reduce the burden of scientists to search and acquire data as much as possible.

 

We present the EMSO ERIC DataLab web application, which provides users with capabilities to preview harmonized data from the EMSO ERIC observatories, perform some basic data analyses, create or modify datasets, and download them. Use case scenarios of the DataLab include the creation of a NetCDF file with time-series information across EMSO ERIC observatories.

The DataLab has been developed using engineering best practices and trend technologies for big data management, including specialized Python libraries for web environments and oceanographic data analysis, such as Plotly, Dash, Flask, and the Module for Ocean Observatory Data Analysis (MOODA).
Radial Evolution of Inverted Heliospheric Magnetic Field Between 0.3 and 1 AU
Authors: Macneil Allan , Owens Mathew , Wicks Robert , Lockwood Mike , Lang Matthew , Bentley Sarah
Published: March 2020

Local inversions, or ‘switchbacks’, in the heliospheric magnetic field (HMF) have recently been identified as prominent features in the inner heliosphere through observations by Parker Solar Probe. These inversions coincide with spikes in radial velocity, and have been interpreted as possibly being the result of jets originating in the corona. While magnetic inversions with similar properties to these jets have also been observed by Helios around its perihelion of ~0.3 AU, inversions with a range of properties and scales have long been studied at distances of 1 AU and beyond. The processes which form the inversions seen outside of 0.3 AU, and whether they are a result of solar wind formation in the solar corona or the transport of solar wind through the heliosphere, are not clear. We present a statistical study on the occurrence of inverted heliospheric magnetic field using Helios 1 observations spanning heliocentric distances 0.3—1 AU. The evolution of inversion occurrence allows us to identify probable locations in the heliosphere where inversions may be produced. Based on these results, we make suggestions as to which processes are most likely responsible for inverted HMF observed between 0.3 and 1 AU.
Satellite-Based Analysis of Fire Events and Transport of Emissions in the Arctic
Authors: Sundström Anu-Maija , Karppinen Tomi , Arola Antti , Sogacheva Larisa , Lindqvist Hannakaisa , de Leeuw Gerrit , Tamminen Johanna
Published: March 2020

Climate change is proceeding fastest in the Arctic region. During past years Arctic summers have been warmer and drier elevating the risk for extensive forest fire episodes. In fact, satellite observations show, that during past two summers (2018, 2019) an increase is seen in the number of fires occurring above the Arctic Circle, especially in Siberia. While human-induced emissions of long-lived greenhouse gases are the main driving factor of global warming, short-lived climate forcers or pollutants emitted from the forest fires are also playing an important role especially in the Arctic. Absorbing aerosols can cause direct arctic warming locally. They can also alter radiative balance when depositing onto snow/ice and decreasing the surface albedo, resulting in subsequent warming. Aerosol-cloud interaction feedbacks can also enhance warming. Forest fire emissions also affect local air quality and photochemical processes in the atmosphere. For example, CO contributes to the formation of tropospheric ozone and affects the abundance of greenhouse gases such as methane and CO2.

This study focuses on analyzing fire episodes in the Arctic for the past 10 years, as well as investigating the transport of forest fire CO and smoke aerosols to the Arctic. Smoke plumes and their transport are analyzed using Absorbing Aerosol Index (AAI) from several satellite instruments: GOME-2 onboard Metop A and B, OMI onboard Aura, and TROPOMI onboard Copernicus Sentinel-5P satellite. Observations of CO are obtained from IASI (Metop A and B) as well as from TROPOMI, while the fire observations are obtained from MODIS instruments onboard Aqua and Terra, as well as from VIIRS onboard Suomi NPP.  In addition, observations e.g. from a space-borne lidar, CALIPSO, is used to obtain vertical distribution of smoke and to estimate plume heights.
3D P-wave velocity model of Ireland's crust from controlled source tomography
Authors: Subašić Senad , Rezaeifar Meysam , Piana Agostinetti Nicola , Lebedev Sergei , Bean Christopher
Published: March 2020

We present a 3D P-wave velocity model of the crust and uppermost mantle below Ireland. In the absence of local earthquakes, we used quarry and mining blasts recorded on permanent stations in the Irish National Seismic Network (INSN) and during various temporary deployments. We compiled a database of 1,100 events and around 20,000 P-wave arrivals, with each event associated with a known quarry. The source location uncertainty is therefore minimal. Both source and receiver locations are fixed in time and we used repeating events to estimate the travel time uncertainty for each source-receiver combination. We created a starting 1D velocity model from previously available data, and then used VELEST to calculate a preliminary minimum 1D velocity model. The 1D velocity model enabled us to remove outliers from the data set, and to calculate the final minimum 1D model used as the initial model in the 3D tomographic inversion. The resulting 3D P-wave velocity model will shed new light on the 3D crustal structure of Ireland.
Identifying compound meteorological drivers of extreme wheat yield loss using Lasso regression
Authors: Sauter Christoph , Deidda Cristina , Rahimi Leila , Rivoire Pauline , Tschumi Elisabeth , Vogel Johannes , van der Wiel Karin , Zscheischler Jakob
Published: March 2020

Compound weather events may lead to extreme impacts that can affect many aspects of society including agriculture. The identification of the underlying mechanisms that cause extreme impacts, such as crop failure, is of crucial importance to improve their understanding and forecasting. Here we investigate whether key meteorological drivers of extreme yield loss can be identified using Least Absolute Shrinkage and Selection Operator (Lasso) in a model environment. 
We use yearly wheat yields as simulated by the APSIM crop model driven by 1600 years of daily weather data from a global climate model (EC-Earth v2.3) under present-day conditions for the Northern Hemisphere. We define extreme yield loss as years with yield below the 5th percentile. We apply logistic Lasso regression to predict whether weather conditions during the growing season lead to crop failure. Lasso selects the most relevant variables from a large set of predictors that best explain the target variable via regularization. Our input variables include monthly averaged values of maximum temperature, vapour pressure deficit and precipitation as well as established extreme event indicators such as maximum and minimum temperature during the growing season, diurnal temperature range, total number of frost days, and maximum five-day precipitation sum.
We obtain good model performance in Central Europe and the American Corn Belt, while yield losses in Asian and African regions are less accurately predicted. Model performance and mean wheat yield strongly correlate, i.e. model performance is highest in regions with relatively large mean yield. Based on the selected predictors, we identify regions where crop loss is predominantly influenced by a single variable and regions where it is driven by the interplay of several variables, i.e. compound events. Especially in the Midwest and Eastern regions of the USA, several variables are required to correctly predict yield losses. This illustrates the importance of accounting for the interplay of various weather conditions over the course of the growing season to be able to determine crop yield losses more precisely.
We conclude that the Lasso regression is a useful tool to detect the compound drivers of extreme impacts, which can be applied for other impact variables such as fires or floods. As the detected relationships are of purely correlative nature, more detailed analyses are required to establish the causal structure between drivers and impacts. Furthermore, using the same model environment, the robustness of the identified relationships will be tested in a climate change context.
Characterising landslide processes using limited data: case study on East Sikkim, India
Authors: Heijenk Renée , Malamud Bruce , Dashwood Claire , Wood Joanne , Arnhardt Christian , Reeves Helen
Published: March 2020

Landslide domains are a useful tool for characterising and subdividing a region into homogenous units reflecting the style of landsliding, which is controlled by the environmental characteristics (e.g. geology, relief). Landslide domains can provide a framework for the application of landslide knowledge obtained from a data-rich area across areas within the domain that are less data rich but have similar environmental characteristics. We have constructed landslide domains for East Sikkim using a landslide inventory, geology, relief and expert-based knowledge of landslide processes in the region. First, we catalogued landslide processes in East Sikkim using peer-reviewed literature, supplementing this with the mapping of over 450 translational landslides and debris flows in Google Earth through visual analysis utilising process knowledge from the catalogue. Several dozens of old landslides were mapped with stereographic analysis of four Cartosat-1 stereo pairs (90 km2) captured in March and December of 2011. Morphometric maps were constructed from Aster GDEM. Finally, the driving environmental characteristics for each process have been determined via statistical analyses to inform expert-driven construction of the landslide domains. We find that landslide domains explain landslide processes in East Sikkim well, but they may be limited by the amount of data that is available. The construction of landslide domains is flexible and can be applied to many different areas. Future work includes the testing of large-scale regions and inclusion into susceptibility models, where we hope that they will facilitate the construction of more accurate and representative susceptibility maps.
Leka Ophiolite Complex as analogy to the serpentinization-carbonation system on Mars
Authors: Bultel Benjamin , Krzesińska Agata M. , Loizeau Damien , Lantz Cateline , Poulet François , Austrheim Håkon O. , Harrington Elise M. , Viennet Jean-Christophe , Dypvik Henning , Werner Stephanie C.
Published: March 2020

Jezero Crater is the landing site of the Mars2020 NASA rover. The crater in its early history hosted a paleolake with at least two deltas remaining. The Jezero lake belongs to a larger system - the Nili Fossae region – which exposes a mineralogical assemblage interpreted as a serpentinization/carbonation system [1].  While the main alteration minerals in Jezero are identified, little is known about the accessory minerals. The latter could reveal critical information about the conditions of serpentinization/carbonation [2; 3]. Moreover, several aspects are yet to be solved: Are the carbonates resulting of primary alteration or reworked origin [4]? Is the mineralogical assemblage modified after deposition in the lake (weathering)? What is the nature of the protolith that could contains up to 30% of olivine [5]?

The Nili Fossae-Jezero system has its potential analogue in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Leka Island, Norway, (PTAL collection, https://www.ptal.eu), which records complex weathering of serpentinite formed from mafic to ultramafic rock [6].

We perform petrological and mineralogical analyses on thin sections to characterize the weathering products in Leka samples, and combine with Near Infrared Spectroscopy measurements. We study the significance of the mineralogical assemblages including solid solution composition and nature of accessory minerals. The consequence for habitability potential might be important. Indeed, the amount of H2/CH4 production in mafic or ultramafic system vary significantly [2; 7]. This could represent crucial information that could guide future in-situ operations but could also help for a better interpretation of the remote sensing data.

 

References:

Brown, A. J., et al. EPSL297.1-2 (2010): 174-182.

Klein, F., et al. Lithos178 (2013): 55-69.

Gysi, A. P., & A. Stefánsson. GCA75.17 (2011): 4728-4751.

Horgan, B., et al. Second International Mars Sample Return. Vol. 2071. 2018.

Ody, A., et al. JGR: Planets118.2 (2013): 234-262.

Bjerga, A., et al. Lithos227 (2015): 21-36.

Bultel, B. (Doctoral dissertation, Lyon). (2016).
Permafrost thaw increases methylmercury formation in sub-arctic Fennoscandia
Authors: Tarbier Brittany , Jonsson Sofi , Baptista-Salazar Carluvy , Sannel A. Britta K. , Hugelius Gustaf
Published: March 2020

With ongoing climate change, temperatures in the northern latitudes are increasing more than twice as fast as the global mean. This causes thawing of permafrost and the release of carbon and contaminants, including mercury (Hg), which have thus far been immobilized in the frozen soil. The potential release of Hg, and microbial transformation of mobilized inorganic Hg to monomethylmercury (MeHg), presents a risk to ecosystems and human health. MeHg is a neurotoxic substance that is readily taken up and biomagnified in aquatic food webs to dangerous concentrations. Arctic communities are particularly vulnerable to Hg pollution as a result of a diet that often includes high trophic level fish and marine mammals. Despite the ecological and societal consequences of elevated Hg levels and the potential for increased Hg conversion to MeHg in post-thaw wetland environments, much of the Hg cycle in the high North is poorly understood.

While global and northern latitude Hg budgets have been estimated, the effect of permafrost thaw on MeHg formation has not yet been fully investigated. Here, we compared concentrations of total Hg (HgT) and MeHg in intact permafrost samples from palsas and peat plateaus with samples from recently thawed collapse fens and from peatlands unaffected by permafrost dynamics in order to investigate whether permafrost thaw impacts net MeHg formation in peatlands. Our study includes five subarctic permafrost peatland sites located in northern Sweden and Norway. Concentrations of HgT and MeHg in the soil cores ranges from 1.1 to 210 and 0.005 to 28 ng g-1 dry weight, respectively, with higher concentrations in the upper soil horizons. No differences were observed in average HgT and MeHg concentrations between the five sites, including both coastal and inland locations. Interestingly, we observe higher concentrations of MeHg and MeHg:HgT ratios in the collapse fens as compared to the permafrost cores, showing increased net methylation of Hg upon permafrost thaw.
Constraints on the Rheology of the Earth's Deep Mantle from Decadal Observations of the Earth's Figure Axis and Rotation Pole
Authors: Couhert Alexandre , Bizouard Christian , Mercier Flavien , Chanard Kristel , Greff Marianne , Exertier Pierre
Published: March 2020

The over four decades long record of Satellite Laser Ranging (SLR) observations to a variety of historical geodetic spherical satellites makes it possible to directly observe the long-term (seasonal to decadal time scales) displacement of the Earth’s mean axis of maximum inertia, namely its principal figure axis, with respect to the crust, through the determination of the degree-2 order-1 geopotential coefficients over the 34-year period 1984—2017.

On the other hand, the pole coordinate time series (mainly from GPS and VLBI data), yield the motion of the rotation pole with even a greater accuracy.

The time-dependent nature of the response of the Earth’s mantle to external forces, where it behaves either elastically on short time scales (seconds) or like a viscous fluid over geological time scales (millions of years), is poorly constrained at decadal periods. Here we propose to relate oscillations of the figure axis to those of the Earth’s rotation pole (through the Euler-Liouville equations) to study the mass-related excitation of polar motion and provide global constraints on the rheological properties of the deep Earth.
Water exchange in a coastal archipelago in the northern Baltic Sea
Authors: Miettunen Elina , Tuomi Laura , Myrberg Kai
Published: March 2020

The Archipelago Sea, situated in the northern Baltic Sea, consists of over 40 000 small islands and islets. It is a vulnerable area and suffers from continuous nutrient loading from the catchment and also from the background loading from the surrounding open sea areas. We studied water exchange in this complex coastal archipelago by simulating the water age and currents with a 3D hydrodynamic model COHERENS. The Archipelago Sea model setup has a horizontal resolution of c. 460 m and its boundary conditions are from a model setup that covers the whole Baltic Sea with a resolution of 3.7 km. The current fields produced with the hydrodynamic model were used to simulate the transport patterns of passive tracers through the archipelago with a Lagrangian particle model OpenDrift.

The mean water age was up to three months in the outer archipelago and up to seven months in the narrowest waterways in the inner archipelago. The effect of rivers on the water age was seen mostly only in the inner archipelago. The transport of passive tracer particles from the open sea areas, across the Archipelago Sea, mostly took place through the outer archipelago. The transport of particles from the outer archipelago towards the inner parts of the archipelago was very sensitive to the geometry and number of islands i.e. density of islands in the area. The prevailing wind direction in the area is from SW, this not being optimal for transport from the outer archipelago to the middle archipelago. For example, with the tracer particles from the southern open sea boundary, most transport to the middle archipelago was seen with SE winds. Transport further to the inner archipelago was limited only to few cases. The results show that the inner archipelago areas are relatively sheltered from transport from the open sea areas and the environmental problems there are in a high extent from local origin.
Observation of high-resolution fetch-limited wave growth using CFOSAT near-nadir measurements
Authors: Mironov Alexey , Chapron Bertrand
Published: March 2020

CFOSAT is the joint space mission of the French (CNES) and Chinese (CNSA) space agencies dedicated to the observation of ocean surface wind and waves. Two main on-board payloads, the Ku-band near-nadir wave scatterometer SWIM and dual-polarization Ku-band wind scatterometer SCAT for the first time provide regular synchronized surface wind vector and sea state observations on a global scale. 
 
After the first year of the mission, SWIM innovative wave scatterometer conception proved to be suitable for space-born directional wave spectra measurements. The overall performance of the instrument and the quality of inverted data are close to the planned specifications. Moreover, in particular cases, precise wave parameters can be estimated even in limited coastal seas with varying wave and wind conditions.
 
In this work, we will show examples of high-resolution directional wave spectrum fetch evolution as observed by CFOSAT mission. The present analysis was performed for areas with fetch-determined conditions, during periods when waves were generated by strong coastal winds. The dataset includes spectra starting from young wind waves (~20 km fetch distance) to mature almost developed sea state (>450 km fetch). The unique multi-beam configuration of SWIM provides multiple estimates of wave spectral parameters all over the sensor footprint along the satellite track. This allows the capturing of the very fine details of spectral variability with distance from the coast. It will be shown, the observed deviation of direction and wavelength of the measured spectral peak from a wave growth fetch law can be attributed to time-varying or topography-induced coastal wind field inhomogeneities. In some cases, this can be explained by local surface current configuration. The obtained results can be directly compared with third party remote sensing observations, numerical model outputs, classical wave fetch-growth laws, and existing empirical parametrizations. 
Going from stable creep to aseismic slow slip events in the ductile realm
Authors: Thielmann Marcel , Duretz Thibault
Published: March 2020

The accommodation of motion on faults spans a large spectrum of slip modes, ranging from stable creep to earthquakes. While seismic slip modes certainly have the largest impact on the surface due to the induced ground shaking, it has been recognized that slow aseismic slip modes relax most of the accumulated stresses on a fault. It has also been suggested that aseismic slip controls seismic events, thus making this kind of slip mode key for earthquake prediction.

Despite the importance of aseismic slow slip, its underlying physical mechanisms are still unclear. Commonly, slow slip events are modeled in terms of frictional failure, employing a rate-and-state model of fault friction, often also invoking fluids that alter frictional properties on the fault. However, at larger depths, frictional processes become increasingly difficult to activate due to the increase in ambient pressure and ductile processes are more likely to dominate deformation.

Here we therefore investigate deep aseismic slip processes governed by ductile deformation mechanisms using 2D numerical models, where we employ a composite viscoelastic rheology combined with grain size reduction and shear heating as weakening processes. We show that the collaborative action of these two weakening mechanisms is sufficient to create the entire spectrum of aseismic slip, ranging from stable creep to long-term slow slip events. The results show that ductile deformation does not necessarily result in stable slip and induces slip modes with considerably larger velocities than the far-field plate velocities. Moreover, the propagation of ductile ruptures induces large stresses in front of the rupture tip which may also trigger short-term seismic events.
Historical and future climates over the Upper and Middle Reaches of the Yellow River Basin revealed by a regional climate model in CORDEX
Authors: Wang Xuejia , Chen Deliang , Pang Guojin , Yang Meixue
Published: March 2020

Despite the importance of the Yellow River to China, regional climate change over the middle reach of the Yellow River Basin (YRB) is much less assessed than other regions. This work focuses on historical and future spatiotemporal changes in mean and extreme temperature and precipitation over the upper and middle reaches of the YRB. The future mean and extreme climates for near-term (2021−2040), mid-term (2041−2060), and far-term (2081−2100) in relation to the historical (1976−2005) period are investigated based on the latest REgional MOdel (REMO). REMO driven by three CMIP5 GCMs under historical and future (RCP 2.6 and 8.5) forcings, following the Coordinated Regional Climate Downscaling Experiment (CORDEX) protocol for the East Asia domain at a spatial resolution of 0.22°, are provided by the Climate Service Center Germany (GERICS). The results show that REMO reproduces the historical mean climate state and six selected climate extreme indices reasonably well, although cold and wet biases still exist. For the far-term, mean temperature rise in winter is most remarkable, with an average of 5.9 °C under RCP8.5. As expected, future temperatures of the warmest day and the coldest night would increase and the number of frost days (FD) would decline considerably. Further, high altitude region would experience a higher mean temperature increase than low altitude region, which is likely caused by the snow-albedo feedback. The decline in FD would increase with elevation, especially under a higher emission. A substantial precipitation increase (32%) would occur in winter under RCP8.5 for the far-term period. Precipitation projections in summer and autumn vary spatially, decrease under RCP2.6 whereas increase under RCP8.5 in the whole YRB for the far-term period. Meanwhile, interannual variability of mean precipitation is expected to increase over most parts of the YRB. Future precipitation extremes, such as the daily intensity and maximum five-day precipitation are projected to increase, and the number of consecutive dry days would decline by the end of the 21st century under the RCP8.5 scenario. The results highlight that the pronounced warming in the high-altitude region together with more intense rainfall extremes could lead to increased future flood risk in the middle and lower reaches of the YRB if the high GHGs emission pathway will be followed.