bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetotellurics in the Eger Rift: An overview of subsurface imaging of different tectonic features
Authors: Weckmann Ute , Platz Anna , Aleid Basel , Willkommen Gregor , Mair Johannes , Klanica Radek , Kovacikova Svetlana , Rulff Paula
Published: March 2021

The Bohemian Massif represents the easternmost part of the geodynamically active European Cenozoic Rift System. This region hosts the contact between three tectonic units of the Variscan Belt, the NE-SW trending Eger Rift and the NNW-SSE striking Marianské Lázne fault. It is characterised by ongoing magmatic processes in the intra-continental lithospheric mantle, repeated earthquake swarms, extensive CO2 degassing in mineral springs and mofettes and the presence of Quaternary volcanoes. While the ICDP drilling programme utilizes information gathered within shallow boreholes in the region, we applied the Magnetotelluric (MT) method to obtain site characterizations in the vicinity of the proposed drill sites. The electrical conductivity has proven to be an important parameter to image the above-mentioned tectonic from the lower crust to the shallow subsurface as well as on a regional and a local scale. Here, we present 2D and 3D inversion models of different MT and Radio-MT (RMT) experiments to study e.g. the Hartouŝov mofette fields, the Quaternary scoria cones, the regional faults and their interplay. Thereby the experiments were designed that we can use lower frequency data from MT to support shallow 3D inversions of e.g. the scoria cones in the regions. The most prominent large-scale conductivity features map channels from the lower crust to the surface possibly forming pathways for fluids into the region of earthquake swarms, mofette fields and know spas. However, the locations of the scoria cones seem to be bound to regional fault zones.
Complete Enclosure of Stunted Trees to Study Greenhouse Gas Fluxes in Birch-Invaded Peatland
Authors: Barrop William , Anderson Russell , Andersen Roxane , Toet Sylvia
Published: March 2021

Ombrotrophic, naturally open peatlands are increasingly susceptible to invasion by scrub and trees due to human disturbance, N deposition and climate change. There is limited research on the effect these trees have on ecosystem functions and their removal can be costly, making decisions over best management practice challenging. The adverse growing conditions associated with many of these peatlands can result in stunted tree growth meaning that complete enclosure of a tree remains a practical possibility. In this study we aim to quantify the CH4 and CO2 fluxes from whole trees growing on a disturbed peatland and assess their significance relative to the fluxes between the vegetated peat surface and atmosphere. We also aim to identify if the establishment of trees impacts CH4 and CO2 fluxes from the vegetated peat surface, as compared to adjacent uninvaded peatland.

We have developed a removable chamber capable of enclosing whole trees of up to 3 metres high, making it suitable for use on juvenile or stunted trees. Being able to enclose an entire tree removes potential errors caused by estimating whole tree fluxes by upscaling measurements from a subsample of tree surfaces. The chamber is constructed with a transparent membrane and removable cover so that light and dark measurements can be taken. We use the chamber to take CH4 and CO2 flux measurements on a site with approximately 20-year-old silver birch trees (Betula pendula) of an average height of 2-3 metres. Flux measurements have been taken from the trees and ground collars at different times of year. We have also studied diurnal variation.

Our initial results have shown that the trees on our site are emitters of CH4, although this emission is small in comparison to that produced by the rest of the habitat. The vegetated peat surface in the wooded area had lower CH4 emission but reduced CO2 uptake as compared to the open area. The diurnal study on one tree indicates that methane emissions increase at night. A further diurnal study is planned to explore this further. This study extends the limit on the size of vegetation that can be sampled by a manually operated flux chamber.
Composition and concentrations of aerosol precursor gases in the sub-Arctic boreal forest
Authors: Jokinen Tuija , Lehtipalo Katrianne , Neitola Kimmo , Sarnela Nina , Laitinen Totti , Kulmala Markku , Petäjä Tuukka , Sipilä Mikko
Published: March 2021

One way to form aerosol particles is the condensation of oxidized atmospheric trace gases, such as sulfuric acid (SA) into small molecular clusters. After growing to larger particles by condensation of low volatile gases, they can affect the planets climate directly by scattering light and indirectly by acting as cloud condensation nuclei. Observations of low-volatility aerosol precursor gases have been reported around the world but long-term measurement series and Arctic data sets showing seasonal variation are close to non-existent. In here, we present ~7 months of aerosol precursor gas measurements performed with the nitrate based chemical ionization mass spectrometer (CI-APi-TOF). We deployed our measurements ~250 km above the Arctic Circle at the Finnish sub-Arctic field station, SMEAR I in Värriö. We report concentration measurements of the most common new particle formation related compounds; sulfuric acid, methanesulfonic acid (MSA), iodic acid (IA) and highly oxygenated organic compounds, HOMs. At this remote measurement site, surrounded by a strict nature preserve, that gets occasional pollution from a Russian city of Murmansk, SA is originated both from anthropogenic and biological sources and has a clear diurnal cycle but no significant seasonal variation, while MSA as an oxidation product of purely biogenic sources is showing a more distinct seasonal cycle. Iodic acid concentrations are the most stable throughout the measurement period, showing almost identical peak concentrations for spring, summer and autumn. HOMs are abundant during the summer months and due to their high correlation with ambient air temperature, we suggest that most of HOMs are products of monoterpene oxidation. New particle formation events at SMEAR I happen under relatively low temperatures, low relative humidity, high ozone concentration, high SA concentration in the morning and high MSA concentrations in the afternoon. The role of HOMs in aerosol formation will be discussed. All together, these are the first long term measurements of aerosol forming precursor from the sub-arctic region helping us to understand atmospheric chemical processes and aerosol formation in the rapidly changing Arctic.

 

 
Scaling seismic fault thickness from the laboratory to the field
Authors: Ferrand Thomas P. , Nielsen Stefan , Labrousse Loïc , Schubnel Alexandre
Published: March 2021

Pseudotachylytes originate from the solidification of frictional melt, which transiently forms and lubricates the fault plane during an earthquake. Here we observe how the pseudotachylyte thickness a scales with the relative displacement D both at the laboratory and field scales, for measured slip varying from microns to meters, over six orders of magnitude. Considering all the data jointly, a bend appears in the scaling relationship when slip and thickness reach ∼1 mm and 100 µm, respectively, i.e. MW > 1. This bend can be attributed to the melt thickness reaching a steady‐state value due to melting dynamics under shear heating, as is suggested by the solution of a Stefan problem with a migrating boundary. Each increment of fault is heating up due to fast shearing near the rupture tip and starting cooling by thermal diffusion upon rupture. The building and sustainability of a connected melt layer depends on this energy balance. For plurimillimetric thicknesses (a > 1 mm), melt thickness growth reflects in first approximation the rate of shear heating which appears to decay in D−1/2 to D−1, likely due to melt lubrication controlled by melt + solid suspension viscosity and mobility. The pseudotachylyte thickness scales with moment M0 and magnitude MW; therefore, thickness alone may be used to estimate magnitude on fossil faults in the field in the absence of displacement markers within a reasonable error margin.
Wet in the Anthropocene – a report of exceptionally stable hydrological conditions in a small bog over the last 1500 years
Authors: Marcisz Katarzyna , Kołaczek Piotr , Gałka Mariusz , Diaconu Andrei-Cosmin , Lamentowicz Mariusz
Published: March 2021

Over the last few hundred years peatlands worldwide are experiencing substantial drying that is lowering their carbon storage potential. However, our high-resolution reconstruction of hydrological changes in a small Sphagnum-dominated peatland show that we can still observe healthy bogs in the fragmented landscape of Europe (Marcisz et al., 2020). We investigated last 1500 years history of a bog located in a young glacial landscape in Central Eastern Europe (NE Poland) using a multi-proxy approach and high-resolution dating. Our reconstruction showed a rare case of hydrological stability in the peatland that did not experience any dry shift over the last 1500 years, allowing for an undisturbed growth of Sphagnum, stable microbial communities, and high peat accumulation rates. High water tables (>12 cm depth to water table) influenced high resilience of the bog which was not affected by disturbances (deforestations, grazing or farming). Our palaeoecological data suggest that nature conservation practices which target high water tables are essential to maintain peatlands as a sink and not as a source of carbon in the future, supporting an earlier study that concluded a ca. 11-12 cm water table depth as a target number for peatland protection (Lamentowicz et al., 2019).

References:

Lamentowicz, M., Gałka, M., Marcisz, K., Słowiński, M., Kajukało-Drygalska, K., Druguet Dayras, M., Jassey, V.E.J., 2019. Unveiling tipping points in long-term ecological records from Sphagnum-dominated peatlands. Biology Letters 15, 20190043.

Marcisz, K., Kołaczek, P., Gałka, M., Diaconu, A.-C., Lamentowicz, M., 2020. Exceptional hydrological stability of a Sphagnum-dominated peatland over the late Holocene. Quaternary Science Reviews 231, 106180.
Solar Orbiter/Radio and Plasma Wave observations during the first Venus flyby
Authors: Edberg Niklas J. T. , Hadid Lina , Maksimovic Milan , Bale Stuart D. , Chust Thomas , Khotyaintsev Yuri , Krasnoselskikh Volodya , Kretzschmar Matthieu , Lorfèvre Eric , Plettemeier Dirk , Souček Jan , Steller Manfred , Štverák Štěpán , Trávníček Pavel , Vaivads Andris , Vecchio Antonio , Horbury Tim ,   RPW team & MAG team
Published: March 2021

We present measurements from the Radio and Plasma Wave (RPW) instrument suite onboard the Solar Orbiter mission during the first Venus encounter. RPW consists of several units and is capable of measuring both the electric and magnetic field fluctuations with three electric antennas and a search-coil magnetometer: The Low Frequency Receiver (LFR) cover the range from DC up to 10kHz when measuring the electric and magnetic waveform and spectra; the Thermal Noise and High Frequency Receiver (TNR-HFR) determines the electric power spectra and magnetic power spectra from 4kHz-20MHz, and 4kHz to 500kHz, respectively, to determine properties of the electron population; the Time Domain Sampler (TDS) measures and digitizes onboard the electric and magnetic field waveforms from 100 Hz to 250 kHz. The BIAS subunit measures DC and LF electric fields as well as the spacecraft potential, which gives a high cadence measure of the local plasma density when calibrated to the low-cadence tracking of the plasma peak from the TNR. Solar Orbiter approached Venus from the induced magnetotail and had its closest approach at an altitude of 7500 km over the north pole of Venus on 27 Dec 2020. The RPW instruments observed a tail region that extended several 10’s of Venus radii downstream of the planet. The induced magnetosphere was characterized to be a highly dynamic environment as Solar Orbiter traversed the downstream tail and magnetosheath before it crossed the Bow Shock outbound at ~12:40 UT. Polarized whistler waves, high frequency electrostatic waves, narrow-banded emissions, possible electron double layers were observed. The fine structure of the bow shock could also be investigated in detail. Solar Orbiter could hence enhance the knowledge of the structure of the solar wind-Venus interaction.
Is the thermal stability of soil organic matter related to its biogeochemical stability in cultivated Arenosols of the groundnut basin of Senegal?
Authors: Malou Oscar Pascal , Chevallier Tiphaine , Sebag David , Moulin Patricia , Badiane Ndour Ndèye Yacine , Rakotondrazafy Nancy , Thiam Abou , Chapuis-Lardy Lydie
Published: March 2021

Soil carbon (C), now more than ever, attracts the interest of the scientific community for its importance in combating climate change and achieving food security. As a result, its key role in agricultural soil fertility and in anthropogenic greenhouse gas emissions mitigation is high on international agendas. A key issue regarding the linkage between food security and carbon storage concerns the mineralization or the stability of soil organic matter (SOM). Rock-Eval® analysis was used to examine the thermal stability of SOM and these results were presented in details at the EGU General Assembly in 2020 (EGU2020-11229). Several indicators are used to further appreciate the quantity and quality of SOM: particle size fractionation (POM-C), determination of permanganate oxidizable carbon (POX-C) and carbon mineralization kinetics (Min-C). The results of both approaches are crossed and presented here. Soils were sampled from two soil layers (0-10 et 10-30 cm) in agricultural plots representative organic inputs practices in local agricultural systems (No input, +Millet residues, +Manure and +Organic wastes). Total soil organic carbon (SOC) concentrations ranged from 1.8 to 18.5 g C.kg-1 soil (mean ± standard deviation: 5.6 ± 0.4 g C.kg-1 soil) in the surface layer (0-10 cm) and from 1.5 to 11.3 g C.kg-1 soil (mean ± standard deviation: 3.3 ± 0.2 g C.kg-1 soil) in 10-30 cm deep layer. The soil organic matter in these Arenosols while positively affected by organic inputs is dominated by thermally labile forms. The POM-C fractions represent respectively 45 % and 24 % of the COS in the 0-10 cm and 10-30 cm soil layers respectively. Permanganate oxidizable carbon (POX-C) and mineralizable C (Min-C) averaged 254 ± 14 mg C.kg-1 soil and 10.7 ± 1.2 mg C-CO2 kg-1 soil in the 0-10 cm layer. Our results show that in different situations, the labile pools POM-C, POX-C and Min-C are linked to the active thermal pools A1 (highly labile pool), A2 (labile pool), A3 (resistant pool) and even A4 (refractory pool). The A3 and A4 pools, which are known to be relatively stable in more clayey soils, are in fact quickly mineralized in the sandy soils of this region. This intense mineralization of SOM promotes the recycling of nutrients which is excellent for productivity of these agrosystems, but not for mitigation of climate change in the long term.

keywords: Sahel ; Arenosols ; Thermal stability ; Biogeochemical stability ; Rock-Eval analysis, POM-C ; POX-C ; Min-C.
Application of equilibrium theory on alluvial channel-form adjustment in a large river heavily loaded with sediment
Authors: Huang He Qing , Zhang Min , Su Teng , Yu Guoan
Published: March 2021

Taking the width/depth ratio of an alluvial channel as an independent variable, a variational analysis of basic flow relationships shows that flow is able to achieve stationary equilibrium by adjusting channel geometry when the condition of maximum flow efficiency (MFE) is satisfied. To examine if this theory of self-adjusting channel morphodynamics can be practically applied to large river systems heavily loaded with sediment, this study examines the degree of correspondence between theoretically determined equilibrium channel geometries and actual measurements along the lower Yellow River. Using the Meyer-Peter and Müller bedload relation modified on the basis of MFE theory and relations of flow continuity and resistance we present a detailed investigation of the potential physical causes and main factors resulting in the correspondence. 
Precision Mid-Infrared Frequency Comb Spectroscopy using a Cross-Dispersed Spectrometer
Authors: Bailey D. Michelle , Zhao Gang , Fleisher Adam J.
Published: March 2021

Advances in optical technology have led to the commercialization and widespread use of broadband optical frequency combs for multiplexed measurements of trace-gas species. Increasingly available in the mid-infrared spectral region, these devices can be leveraged to interrogate the molecular fingerprint region where many fundamental rovibrational transitions occur. Here we present a cross-dispersed spectrometer employing a virtually imaged phased array etalon and ruled diffraction grating coupled with a difference frequency generation comb centered near 4.5 µm. The spectrometer achieves sub-GHz spectral resolution with a 30 cm-1 instantaneous bandwidth. Laboratory results for nitrous oxide isotopic abundance retrieval will be presented. Challenges relating to characterizing the instrument lineshape function, constructing a frequency axis traceable to the comb, and accurate spectral modelling will be addressed and progress towards incorporating a more compact laser frequency comb source into the system will be discussed.
Modelling climate change impacts on glaciers and water resources in China  using OGGM and FUSE
Authors: Goldberg Dan , Kinnear Louis , Kobierska-Baffie Florian , Addor Nans , He Helen , Zha Qianyu , Reyniers Nele , Maussion Fabien
Published: March 2021

Hundreds of millions of people depend strongly on hydrological inputs in the mountainous regions of China and central Asia. Glacier runoff is a major contributor to this hydrological forcing, yet many glaciers in the region have undergone mass loss in recent years and this mass loss is expected to continue or increase in response to climatological change. As such it is important to assess the large-scale response of High Mountain Asia glaciers to climate change , and its effects on hydrology. We present here preliminary modelling investigations of glacier change and hydrological impacts in response to high-resolution climate model projections over the 21st century as a component of the project SWARM (Impacts Assessment to Support WAter Resources Management and Climate Change Adaptation for China). Our model chain consists of i) Open Global Glacier Model (OGGM), which allows for high-resolution glacier flowline modelling of multiple glaciers, and ii) the Framework for Understanding Structural Errors (FUSE) a modular framework for snow and hydrology modelling, which we used to assemble and run three hydrological models over the whole of China. Both FUSE and OGGM are forced by an ensemble of bias-corrected CORDEX-East Asia regional climate models (in turn forced by CMIP5 general circulation models), and outputs of OGGM are provided to FUSE. We discuss our application of OGGM to 80,000 glaciers in Chinese river catchments; our efforts to calibrate the mass balance model using an expanded set of geodetic mass balance constraints; and finally the projections of glacier, snow and streamflow changes in the 21st century. In particular, we discuss the robustness and uncertainties in the projections as sampled by our multi-model ensemble.
Sea-state contributions to sea-level variability in the European Seas
Authors: Bonaduce Antonio , Staneva Joanna , Grayek Sebastian , Bidlot Jean-Raymond , Breivik Øyvind
Published: March 2021

The contribution of sea-state-induced processes to sea-level variability is investigated through ocean-wave coupled simulations. These experiments are performed with a high-resolution configuration of the Geestacht COAstal model SysTem (GCOAST), implemented in the Northeast Atlantic, the North Sea and the Baltic Sea which are considered as connected basins. The GCOAST system accounts for wave-ocean interactions and the ocean circulation relies on the NEMO (Nucleus for European Modelling of the Ocean) ocean model, while ocean-wave simulations are performed using the spectral wave model WAM. The objective is to demonstrate the contribution of wave-induced processes to sea level at different temporal and spatial scales of variability. When comparing the ocean-wave coupled experiment with in situ data, a significant reduction of the errors (up to 40% in the North Sea) is observed, compared with the reference. Spectral analysis shows that the reduction of the errors is mainly due to an improved representation of sea-level variability at temporal scales up to 12 h. Investigating the representation of sea-level extremes in the experiments, significant contributions (> 20%) due to wave-induced processes are observed both over continental shelf areas and in the Atlantic, associated with different patterns of variability. Sensitivity experiments to the impact of the different wave-induced processes show a major impact of wave-modified surface stress over the shelf areas in the North Sea and in the Baltic Sea. In the Atlantic, the signature of wave-induced processes is driven by the interaction of wave-modified momentum flux and turbulent mixing, and it shows its impact to the occurrence of mesoscale features of the ocean circulation. Wave-induced energy fluxes also have a role (10%) in the modulation of surge at the shelf break.
Deep learning-based downscaling of seasonal forecasts over the Iberian Peninsula
Authors: Gómez-Gonzalez Carlos Alberto , Palma Garcia Lluís , Lledó Llorenç , Marcos Raul , Gonzalez-Reviriego Nube , Carella Giulia , Soret Miravet Albert
Published: March 2021

Seasonal climate predictions can forecast the climate variability up to several months ahead and support a wide range of societal activities. The coarse spatial resolution of seasonal forecasts needs to be refined to the regional/local scale for specific applications. Statistical downscaling aims at learning empirical links between the large-scale and local-scale climate, i.e., a mapping from a low-resolution gridded variable to a higher-resolution grid.

Statistical downscaling of gridded climate variables is a task closely related to that of super-resolution in computer vision, and unsurprisingly, several deep learning-based approaches have been explored by the climate community in recent years. In this study, we downscale the SEAS5 ECMWF seasonal forecast of temperature over the Iberian Peninsula using deep convolutional networks in supervised and generative adversarial training frameworks. Additionally, we apply the traditional analog method for statistical downscaling, which assumes that similar atmospheric configurations (e.g., the predictors) lead to similar meteorological outcomes in a K-Nearest Neighbors fashion. 

The deep learning-based algorithms are trained on the UERRA gridded temperature  dataset and several ERA5 reanalysis predictor variables. Finally, we evaluate the accuracy of our deep learning-based downscaling of SEAS5 temperature and compare it to the analog downscaling and a bicubic interpolation, as the simplest baseline method.
High-resolution weather simulation for sub-Saharan Africa on the World Community Grid
Authors: Le Coz Camille , Yu Qidi , Treinish Lloyd A. , Alvarez Manuel Garcia , Cryan Ashley , van de Giesen Nick
Published: March 2021

Rainfall in Africa is difficult to estimate accurately due to the large spatial variability. Most of the monsoon rainfall is generated by convective rainstorms that can be very localized, sometimes covering less than 100 km2. The goal of the African Rainfall Project is to run the Weather and Research Forecast (WRF) model for sub-Saharan Africa at a convection-permitting resolution in order to better represent such rainfall events. The resolution will be 1km, which is finer than most studies over Africa, which typically use resolutions of 3km or more. Running WRF for such a large area at such a high resolution is computationally expensive, which is where IBM’s World Community Grid comes in. The World Community Grid (WCG) is part of the Social Corporate Responsibility of IBM that crowdsources unused computing power from volunteers devices and donates it to scientific projects.

The simulation was adapted to the WCG by dividing the simulation of one year over sub-Saharan Africa in many smaller simulations of 48h over 52 by 52 km domains. These simulations are small enough to be calculated on a single computer of a volunteer at the required resolution. In total, 35609 overlapping domains are covering the whole of sub-Saharan Africa. During the post-processing phase, the smaller simulations are merged back together to obtain one consistent simulation over the whole continent.

Our main focus is rainfall, as this is the variable with the highest socio-economic impact in Africa. However, the outputs of the simulations include other variables such as the 2m-temperature, the 10m-wind speed and direction. These variables are outputted every 15min. At the end of this project, we will have over 3 billion files for a total of 0.5 PB. The data will be reorganized so that the different variables can be stored, searched and retrieved efficiently. After the reorganization, the data will be made publicly available.

The first validation step will be to examine the impact of dividing sub-Saharan Africa into many smaller domains. This will be done by comparing the simulation from this project to one large simulation. This simulation is obtained by running WRF at a 1km resolution on a large domain (500km by 1000km) for a shorter period, using Cartesius, the Dutch national computer. The second validation step will be to compare the simulations with satellite data and with in-situ measurements from the TAHMO network (www.tahmo.org).
Comparing landslide proximity to roads in national and event landslide inventories
Authors: Heijenk Renée A. , Malamud Bruce D. , Taylor Faith E. , Wood Joanne L.
Published: March 2021

Road influence on landslides is an often-used variable in landslide susceptibility models. However, in many studies, there is limited detail explaining the processes and interactions between roads and landslides; instead a constant road buffer or standard function is used. Here, we present a spatial statistical analysis of landslide proximity to roads across a range of geographic settings and landslide inventory types. We examine the proximity of landslide centroids to roads at regional to national scales using twelve landslide inventories; with a variety of inventory types (6 triggered event, 6 multi-temporal), mapping methods (2 field based, 6 remote sensing, and 4 a combination of the two), and country of origin (6 high and 6 low human development index). Each inventory contains between ≈270 to 81,000 landslides (nLandslides) and covers areas of ≈80 km2 to 385,000 km2.

We have developed a pyQGIS tool that calculates the distance between each landslide centroid and road vectors within the same drainage basin; this make sure no distances are calculated between landslides and roads that are on opposite sides of ridges and therefore do not influence each other. For each landslide inventory, we calculate the distance to the closest road for each landslide. We then compare this distribution that of a set of randomly generated points (number of random points is calculated for each landslide inventory using the equation nLandslides*100) to roads, to test whether landslide occurrence is influenced by road presence.

For ten of the twelve inventories, the results show no strong preference of landslides to occur closer to roads than the random points; the exceptions being landslide inventories that we believe have a bias towards roads due to the mapping remit (e.g. highway agencies). For some of the ten inventories showing no robust relationship with roads, we believe this is related to the location of the roads on the slope (e.g. at the toe, mid-slope or on the ridge), but it is not readily explainable in others. Based on our results, we suggest that a more nuanced use of road proximity within landslide susceptibility models should be adopted, and further research to understand the interactions between landslides and proximity to roads at the regional to national scale.
The future of ski resorts in the Swiss Alps: using DMDU to identify tipping points
Authors: Ashraf Vaghefi Saeid , Muccione Veruska , van Ginkel Kees C.H. , Haasnoot Marjolijn
Published: March 2021

The future of ski resorts in the Swiss Alps is highly uncertain. Being dependent on snow cover conditions, winter sport tourism is highly susceptible to changes in temperature and precipitation. With the observed warming of the European Alps being well above global average warming, snow cover in Switzerland is projected to shrink at a rapid pace. Climate uncertainty originates from greenhouse gas emission trajectories (RCPs) and differences between climate models. Beyond climate uncertainty, the snow conditions are strongly subject to intra-annual variability. Series of unfavorable years have already led to the financial collapse of several low-altitude ski resorts. Such abrupt collapses with a large impact on the regional economy can be referred to as climate change induced socio-economic tipping points. To some degree, tipping points may be avoided by adaptation measures such as artificial snowmaking, although these measures are also subject to physical and economical constraints. In this study, we use a variety of exploratory modeling techniques to identify tipping points in a coupled physical-economic model applied to six representative ski resorts in the Swiss Alps. New high-resolution climate projections (CH2018) are used to represent climate uncertainty. To improve the coverage of the uncertainty space and accounting for the intra-annual variability of the climate models, a resampling technique was used to produce new climate realizations. A snow process model is used to simulate daily snow-cover in each of the ski resorts. The likelihood of survival of each resort is evaluated from the number of days with good snow conditions for skiing compared to the minimum thresholds obtained from the literature. Economically, the good snow days are translated into the total profit of ski resorts per season of operation. Multiple unfavorable years of total profit may lead to a tipping point. We use scenario discovery to identify the conditions under which these tipping points occur, and reflect on their implications for the future of snow tourism in the Swiss Alps.
Wildfire impact on the hydrological conditions of an Alpine slope 
Authors: Corti Monica , Abbate Andrea , Ivanov Vladislav , Papini Monica , Longoni Laura
Published: March 2021

Wildfire events have severe effects over mountain environments, changing dramatically the local terrain hydrogeological conditions and frequently affecting slope stability. Besides burning vegetation, wildfires induce a modification on soil properties that could result in a decreased capacity of infiltration. This leads to an increase of erosion and, potentially, of the related geohazards, such as flash flooding and debris flows, in the vicinity of the affected sites.

Past studies found that this reduced infiltration rate changes over time and the original hydrogeological soil properties are expected to recover in as long as 10 years after the wildfire event, depending on the environmental characteristics and on the soil properties of the site.

Our work aims to investigate the impact of a wildfire on the infiltration conditions of a slope located in the Southern Alps, considering as a case study a wildfire event occurred in Sorico (CO) in December 2018.

The effects of the wildfire on the infiltration rates and the subsequent recovery of the original hydrogeological properties were evaluated over the span of more than two years after the event. Infiltration tests were performed both within the most affected area as well as in the nearest unburnt area. Results were then correlated with precipitation and satellite imagery data in order to retrieve a recovery factor, necessary for the calibration of a simple 1D hydrogeological model.
Deriving plasma parameters of large coronal magnetic loops using J-burst observation from LOFAR
Authors: Zhang Jinge , Reid Hamish
Published: March 2021

Solar type J radio bursts are the signatures of electron beams travelling along closed magnetic loops in the solar corona. Type J bursts provide diagnostics for observing and understanding coronal loops geometry and electron beams dynamics. Due to the observational limitations, large loops around 1 solar radius in height are ill-defined. Whilst J-bursts at meter-wavelengths are well suited for the analysis of coronal loops at these solar altitudes, applying standard empirical solar plasma density distributions have limitations as they are designed for flux tubes extending into the solar wind and do not capture the curvature of such coronal loops.

We analysed over 20 type J bursts observed by the LOw-Frequency ARray (LOFAR) on the 10th of April 2019. Using a reference height, we derived the ambient plasma density models that varied along the ascending leg of coronal loops, and also with solar altitude. By estimating the density scale height, we inferred physical parameters of large coronal magnetic loops, roughly 0.7 to 1.5 solar radii above the photosphere. These coronal loops had temperatures around 2 MK and pressures around  5 dyn cm-2 . We then inferred the minimum magnetic field strength of these closed loops to be around 0.3 G. These large coronal loops' plasma conditions are significantly different to smaller coronal loops and loops that extend out into the solar wind.
Ivermectin transfer through percolation and surface runoff from intact soil mesocosms under rainfall simulation
Authors: Hachgenei Nico , Spadini Lorenzo , Nord Guillaume , Morel Marie-Christine , Lespine Anne , Mora Henri , Courvoisier François , Sutra Jean-François , Duwig Céline
Published: March 2021

Ivermectin (IVM) is one of the few pharmaceutics that are still used in a preventive, systematic manner in extensive cattle breeding in our study region in the Ardèche region (France), amongst others. It is an efficient antiparasitic agent with an extreme acute toxicity for most invertebrates, especially aquatic organisms like daphnia (ng/l), and is also highly toxic to different fish species (µg/l). Due to its strong sorption to soil and sediment and quick photodegradation, early environmental risk assessments (ERA) conclude a low risk for aquatic organisms. More recent studies conclude an inacceptable risk for daphnia and dung organisms. One of the critical parameters between these contradictory conclusions is IVM export from cow dung and transfer towards the streams.

The study region is characterized by a Mediterranean climate with a dry summer and intense convective storm events leading to regular flash flood events that coincide with the cattle treatment seasons in spring and autumn. The study region encompasses the Claduègne catchment which is part of the OHMCV observatory and the OZCAR and eLTER research infrastructures.

The key question concerning the risk for aquatic organisms is to what extent and in which conditions IVM is mobilized and transferred from cow dung to soil and river via surface runoff and percolation in this environment prone to rapid flow processes. We approach this question on the scale of 60*30*22 (L*W*D) cm3 intact soil mesocosms, for which we developed an adapted field sampling and laboratory experimentation case. Soil mescosms are collected in the Claduègne catchment. IVM is applied in form of spiked cow dung at realistic environmental concentrations before simulating several rainfall events, representative of this Mediterranean region. Runoff and drainage water are sampled for major anions (including Br- tracer), non-particulate organic carbon and IVM concentrations on a high temporal frequency in order to gain an insight on the intra- and inter-event dynamics of water and IVM transfer. Tested parameters include dung ageing, soils types, initial soil humidity and consecutive rainfall events.

The first results highlight the importance of runoff for the overall export of IVM on the event scale. Concerning the water flux, initial humidity is found to determine the runoff / drainage partitioning as well as the rapidity of percolation through the occurrence of preferential flow. In this context, hydrophobicity seems to play an important role.
The potential of TanDEM-X repeat acquisitions to monitor elevation and mass changes of Arctic and Antarctic glaciers
Authors: Sommer Christian , Seehaus Thorsten , Sochor Lukas , Malz Philipp , Braun Matthias
Published: March 2021

The large ice caps and glaciers of the northern and southern polar regions have the potential to contribute significantly to global sea-level rise, yet measurements of glacier mass changes in those regions are scarce and difficult due to harsh conditions and the size of Arctic and Antarctic glacier areas. Acquisitions of the synthetic aperture radar satellite mission TanDEM-X provide valuable insights into glacier dynamics in those regions as the X-band radar is independent from clouds and illumination and can resolve elevation changes of large glacierized areas as well as individual glaciers. We use specifically generated and coregistered digital elevation models (DEM) from repeated TanDEM-X data takes to derive glacier elevation changes between 2010 and 2020.

For the Arctic regions, we already calculated elevation changes for the Russian Arctic archipelagos from TanDEM-X acquisitions (2000-2017). Currently, we are preparing similar TanDEM-X DEM differences for Arctic glaciers outside the Greenland ice sheet (Svalbard, Iceland, Alaska, Canadian Arctic, Scandinavia and North Asia). In contrast to the wide and smooth areas of the East and West Antarctic ice sheets, the steep topography of the Antarctic Peninsula strongly limits the application of altimeter data for accurately quantifying glacier mass changes. Therefore, we computed glacier mass changes along the Antarctic Peninsula by means of TanDEM-X data.

Additionally, measurements of the IceSAT2 laser altimeter will be integrated in the analysis to improve the estimation of radar signal penetration into snow and firn and thereby reduce the elevation change and mass balance uncertainties.
Rainfall estimates from opportunistic sensors in Germany across spatio-temporal scales – Geostatistical interpolation framework
Authors: Eisele Micha , Graf Maximilian , El Hachem Abbas , Seidel Jochen , Chwala Christian , Kunstmann Harald , Bárdossy András
Published: March 2021

Precipitation - highly variable in space and time - is the most important input for many hydrological models. As these models become more and more detailed in space and time, high-resolution input data are required. Especially for modeling and prediction in fast reacting catchments, such as urban catchment areas, a higher space-time resolution is needed than the current ground measurement networks operated by national weather services usually provide. With the increasing number and availability of opportunistic sensors such as commercial microwave links (CMLs) and personal weather stations (PWS) in recent years, new opportunities for measuring meteorological data are emerging.

We developed a geostatistical interpolation framework which allows a combination of different opportunistic sensors and their specific features and geometric properties, e.g. point and line information. In this framework, a combined kriging approach is introduced, taking into account not only the point information of a reliable primary network, e.g., from national weather services, but also the higher uncertainty of the PWS- and CML-based precipitation. The path-averaged information of the CMLs is included through a block kriging-type approach.

The methodology was applied for two 7-months periods in Germany using an hourly temporal and a 1x1 km spatial resolution. By incorporating CMLs and PWS, the Pearson correlation could be increased from 0.56 to 0.73 compared to using only primary network for interpolation. The resulting precipitation maps also provided good agreement compared to gauge adjusted radar products.
DInSAR monitoring of glacier dynamics in Cordillera Blanca and Vilcabamba
Authors: Riveros Lizana Christian , Espinoza Villar Raul , Jara Infantes Harrison , Torres Lazaro Juan Carlos
Published: March 2021

The effects of climate change are causing atypical changes dynamics of tropical glaciers. Conventional methods and optical images were ineffective in measuring these changes periodically due to the complexity of remote mountainous regions and cloud cover. In this research, a Differential Interferometric Synthetic Aperture Radar (DInSAR) analysis has gone performed with Sentinel-1 data from February 2019 to March 2020 in the Cordillera Blanca and Vilcabamba for Mapping displacement and subsidence. The measurements were compared with surface temperature and precipitation, providing zonal statistics to identify and assess regions associated with Glacial Lake Outburst Floods (GLOFs) hazards and enhanced understanding of the glacier dynamics in response to changing climatic conditions.
Potential of VLBI observations to satellites for precise orbit determination
Authors: Mammadaliyev Nicat , Schreiner Patrick , Glaser Susanne , Neumayer Karl Hans , Koenig Rolf , Heinkelmann Robert , Schuh Harald
Published: March 2021

Besides the natural extra-galactic radio sources, observing an artificial Earth-orbiting radio source with the Very Long Baseline Interferometry (VLBI) permits to extend the geodetic and geodynamic applications of this highly accurate interferometric technique. Furthermore, combining aforementioned observations provides a promising method to determine the satellite orbit and delivers the new type of observations such as group delay and delay rate which might be employed to validate the orbit independent of other space geodetic techniques.

In this research, the potential of the interferometric satellite tracking for the Precise Orbit Determination (POD) has been explored based on simulated observations for different scenarios with various VLBI networks, satellite orbits (eccentric low Earth orbits or circular medium Earth orbits) and error sources. POD of the Earth-orbiting satellites is studied on the basis of daily VLBI sessions where satellite observations are scheduled together with the quasar observation for regionally or globally distributed legacy as well as next generation VLBI station networks. In order to simulate VLBI to satellite observations, the influence of the most prominent random error sources in VLBI as well as mismodelling of different force models acting on the satellite are utilized. This study indicates that POD is feasible with VLBI observations and the accuracy mainly depends on the observation geometry.
Inferring ecosystem-level rates of gross primary productivity, respiration, and evapotranspiration with automatic light-dark measurement chambers
Authors: Larsen Klaus Steenberg , Pullens Johannes Wilhelmus Maria , Avila Linsey , Bruun Sander , Chen Ji , Christiansen Jesper Riis , Ibrom Andreas , Larsen Poul , Lærke Poul Erik , Jørgensen Preben , Tariq Azeem
Published: March 2021

In experimental ecosystem ecology, plot sizes are most often too small to apply eddy flux techniques and estimation of ecosystem gas exchange rates relies on various chamber measurement technologies. Furthermore, drained areas often results in increased growth of trees which complicates application of eddy flux measurements on small plots.

We combined ECO2FluX ecosystem-level automatic chambers (prenart.dk) with an LI-8100/LI-8150 multiplexer systems (licor.com) in a range of Danish and Norwegian ecosystems experiments spanning agriculture, grassland/heathlands and peatland ecosystems. The automatic closed, none-steady state chambers each cover an area of 3,117 cm2 (63 cm diameter), are 80 cm tall (volume: 250L), and are capable of switching automatically between transparent and darkened mode, enabling separation of light-sensitive and light-indifferent processes in the ecosystems covered. For CO2 fluxes, net exchange (NEE) was estimated as the flux in transparent mode, ecosystem respiration (RE) in darkened mode, while Gross Ecosystem Productivity (GPP) was estimated as NEE – RE.

Chambers were set up to measure gas concentrations every second using enclosure times of 4-5 minutes, first in light mode and 10-30 minutes later in dark mode, with 3-48 repetitions per day. The longest time series spans 5 years of measurements and contain >60,000 point measurements.

In this presentation, we will present an analysis of the ability of the light-dark chamber data to infer ecosystem-level rates of gross primary productivity, respiration, net CO2 exchange, and evapotranspiration. In the two Norwegian peatland sites, flux measurements may be compared directly with eddy flux measurements. We also compare the rates of the direct estimates of GPP from the light-dark chamber measurements to estimates inferred from using the light (NEE) measurements only followed by applying methodologies normally used for eddy flux measurements. This comparison may help constrain potential biases in both the closed chamber and eddy flux techniques. Finally, we investigate the ability of using such closed chambers to estimate ecosystem evapotranspiration rates at the plot scale. Such application may be useful for estimating the effects on evapotranspiration in field-scale experiments manipulating the ecosystem water balance either directly or indirectly.
The role of Stokes drift in the dispersal of North Atlantic surface marine debris
Authors: Bosi Sofia , Broström Göran , Roquet Fabien
Published: March 2021

Understanding the physical mechanisms behind the transport and accumulation of floating objects in the ocean is crucial in order to efficiently tackle the issue of marine pollution. The main sinks of marine plastic are the coast and the bottom sediment. This study focuses on the former, investigating the timescales of dispersal from the ocean surface and onto coastal accumulation areas through a process called "beaching" in the presence of Stokes drift. Previous literature have found that the Stokes drift can reach the same magnitude as the Eulerian current speed and that it has a long-term effect on the trajectories of floating objects. Two virtual particle simulations are carried out and then compared, one with and one without Stokes drift, named SD and REF respectively. Eulerian velocity and Stokes drift data from global reanalysis datasets are used for particle advection. Particles in the SD model are found to beach at a yearly rate that is almost double the rate observed in the Eulerian model. The main coastal attractors are consistent with the direction of large-scale atmospheric circulation (Westerlies and Trade Winds). Long-term predictions carried out with the aid of adjacency matrices found that the concentration of particles in the subtropical accumulation zone after 100 years is 10 times lower in the presence of Stokes drift. The results confirm the need to accurately represent the Stokes drift in particle models attempting to predict the behaviour of marine debris, in order to avoid overestimation of its residence time in the ocean and guide policies towards prevention and removal more effectively.