bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma parameters inside the cometopause of comet 67P-Churyumov/Gerasimenko
Authors: Williamson Hayley , Stenberg Wieser Gabriella , Nilsson Hans , Moeslinger Anja , Wieser Martin , Canu-Blot Romain
Published: February 2023

Inside the cometopause of comet 67P/Churyumov-Gerasimenko, where cometary ions dominate the ionosphere, is a region of great interest for studying the mass loading of the solar wind. The Rosetta Ion Composition Analyzer (ICA) observed both cometary and solar wind ions in this region during Rosetta’s two year mission orbiting comet 67P. Analysis of this data is complicated by instrumental and spacecraft effects on low energy cometary ion data, which comprises the bulk of the plasma. Recent work has been able to correct the ICA ion distributions for these effects and retrieve low energy ion Maxwellian temperatures and velocities, showing both a cold (< 1 eV) newly ionized plasma and higher energy, warmer pickup ions. Here, we present the varying cometary and solar wind ion temperatures inside the cometopause, with discussion of the causes for the changes in velocity and temperature throughout the time periods studied. In particular, pickup ion distributions vary significantly, from distributions similar to the newly ionized plasma at higher energies to one that decays exponentially with energy. Further, we calculate thermal and dynamic pressures of the cometary and solar wind ions using the retrieved temperatures and velocities, allowing us to analyze the pressure balance between the different plasma components. 
The Dynamics of the India-Eurasia Collision: A Suite of Faulted Viscous Continuum Models Constrained by New High-Resolution Sentinel-1 InSAR and GNSS Velocities
Authors: Fang Jin , Houseman Greg , Wright Tim , Evans Lynn , Craig Tim , Elliott John , Hooper Andy
Published: February 2023

Block versus continuum description of lithospheric deformation in the India-Eurasia collision zone has been hotly debated over many decades. Here we apply the adapted two-dimensional (2-D) Thin Viscous Shell (TVS) approach explicitly accounting for displacement on major faults in Tibet (Altyn Tagh, Haiyuan, Kunlun, Xianshuihe, Sagaing, and Main Pamir Thrust Faults) and investigate the impact of lateral variations in depth-averaged lithospheric strength. We present a suite of dynamic models to explain the key observations from new high-resolution Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) as well as Global Navigation Satellite System (GNSS) velocities. Comparisons between calculated and observed velocity and strain rate fields indicate: (a) internal buoyancy forces from Gravitational Potential Energy (GPE) acting on a relatively weak region of high topography (~2,000 m) contribute to dilatation of high plateau and contraction on the margins; (b) a weak central Tibet (~1021 Pa s relative to far-field depth-averaged effective viscosity of 1022 to 1023 Pa s) yields the observed long-wavelength eastward velocity variation away from major faults; (c) slip resistance on faults produces strain localization and clockwise rotation around the Eastern Himalayan Syntaxis (EHS). We discuss the tectonic implications for rheology of the lithosphere, distribution of geodetic strain, and partitioning of active faulting and seismicity in light of our best-fit geodynamic solutions.
MAX-DOAS measurements of AOT, NO2 and HCHO in Kinshasa (DR Congo): comparisons with TROPOMI and GEOS-CHEM
Authors: Merlaud Alexis , Yombo Phaka Rodriguez , Pinardi Gaia , Mbungu Tsumbu Jean-Pierre , Bopili Mbotia Lepiba Richard , Lomami Djibi Bunenimio , Friedrich Martina , De Smedt Isabelle , Stavrakou Jenny , Muller Jean-François , Hendrick François , Mahieu Emmanuel , Van Roozendael Michel
Published: February 2023

African megacities suffer from air pollution and the problem is expected to worsen in the near-future, with the ongoing explosive demographic growth in these areas. The sources of pollutants in Africa are different from those found in Europe. Agricultural burnings and charcoal-based cooking largely contribute to the NO2 and HCHO burdens. However, many large African cities, such as the City of Kinshasa, capital of the Democratic Republic of Congo, do not have local pollution monitoring capabilities. In these polluted places, space-based measurements are often the only source of data available regarding air quality. Together with the validation of TROPOMI in a poorly sampled area, this context motivated ground-based DOAS observations in Kinshasa since 2017. We first operated a single-axis instrument, which we upgraded as a MAX-DOAS instrument in December 2019.  We describe the observation site in Kinshasa, the MAX-DOAS instrument, and the retrievals which use the algorithmic tools developed within the FRM4DOAS project. We compare the MAX-DOAS database (2019-2023) of ground-based observations of aerosol optical thickness (AOT), NO2 and HCHO with MODIS and TROPOMI, and with simulations using the GEOS-CHEM Chemistry and Transport Model. Such comparisons enable to assess the quality of the satellite products and model performances around Kinshasa. The ground and satellite-based observations have different sensitivities to the trace gas profiles. Combining the observations and model datasets sheds light on the true atmospheric state above Kinshasa. Another objective of this work is to constrain emission inventories in central Africa. 
Examination of the effects of extreme weather events on solar power systems
Authors: Fejes Lilian , Czira Tamás , Pongrácz Rita , Molnár Szabolcs , Talamon Attila
Published: February 2023

Current climate change is characterised by a growing number of extreme weather events and their impacts, which can have a significant impact on energy production, transmission and supply systems, with the potential for severe damage to assets and permanent or intermittent supply disruptions. In order to identify the likely regional climate impacts on specific elements of solar power generation systems, a complex analysis of the expected changes, the sensitivity of infrastructure and the possibilities to adapt to these changes is needed.Accordingly, one of the objectives of the research is to identify and characterize the climatological information and impacts that may pose a risk to solar energy generation facilities in the context of climate change. We investigate the role and significance of extreme weather events and their long-term projected changes for solar power systems in climate impact assessments. The changes of relevant meteorological events due to climate change and their impact on solar energy systems will be evaluated for Hungary based on data from regional climate model simulations available in EURO-CORDEX.
CTX in-flight calibration and data dissemination
Authors: Walter Sebastian H. G. , Munteanu Robert R. C. , Aye Michael
Published: February 2023

The Context Camera (CTX) on board NASA's Mars Reconnaissance Orbiter (MRO) has been in orbit since 2006 and has so far delivered more than 130,000 images. The images are one of the most popular data sets for planetary geologists because the data cover almost the entire planet and have good radiometric resolution, allowing very detailed interpretation of surface features. Since the beginning of the mission, the images have exhibited a darkening effect from the centre of the images towards the edges, creating visible seam lines when multiple images are stitched together. Due to the symmetric decrease in reflectance plots averaged over all lines, this problem is often referred to as "frowning" (see Figure 1 left). Since the standard calibration routines of the Integrated Software for Imagers and Spectrometers (ISIS) only include flatfield files for the first year of the mission, there are no quick and easy standard methods to correct for these artefacts. In this work, we provide an extended in-flight radiometric calibration and the resulting flatfield files that can be used directly in the ISIS environment (see correction example in Figure 1 right). The files are updated regularly and are permanently available in this repository: https://dx.doi.org/10.17169/refubium-37236 .Figure 1: left: CTX image N05_064260_1638 with standard ISIS calibration applied (top) and curve plot of all averaged lines (bottom); right: after additional in-flight calibration the image (top) shows less darkening to the borders and the downward trent in the plot has been removed.In addition, we are in the process of updating our "integrated Mars analysis and research system" (iMars) to include the full set of CTX images, which will be readily processed and made available for download in GIS-compatible formats. As with the previous system, users can select the footprints and visualise the data directly in the map view. Special tools for switching between images with multiple coverage provide an excellent infrastructure for analysing surface changes and seasonal or interannual variations.  We have made a complete overhaul of the graphical interface, which is accessible under https://maps.planet.fu-berlin.de/ctx . This work is supported by the German Space Agency (DLR Bonn), grant 50 OO 2204, on behalf of the German Federal Ministry for Economic Affairs and Energy. We thank the HPC Service of Freie Universität Berlin for computing time.
A Simplified Conceptual Model Using Global Open-Source Datasets to Provide Continental and Global Scale Fluvial Flood Risk.
Authors: Ramsamy Laura , Brennan James , Burke Claire , Reveley Graham , Woodhouse Sally
Published: February 2023

Hydraulic modelling is used to accurately model extreme flood events but comes with high computational costs, significant data requirements, and long simulation times. Increasing computational resources and higher-resolution data with more spatial coverage means that global-scale flood risk modelling capabilities are constantly evolving. Taking a nested approach, we used the HAND-SRC methodology to develop flood risk data at a continent-scale level and identify areas that would benefit from hydraulic modelling at a more granular level.Height Above Nearest Drainage (HAND) is a simplified method used for flood zoning and identifying areas at risk of flooding using a Digital Elevation Model (DEM), and drainage network – which can be derived from the DEM. The HAND-SRC method uses channel geometry estimates, obtained from the DEM, and the Manning’s equation, to develop synthetic rating curves (SRC) which allow the conversion of flood discharges to a water height. The flood height can then be combined with a HAND model to produce a flood map. Existing applications of HAND SRC include Central and Eastern Canada (Scriven et al. 2021), and rivers in Texas and North Carolina (Zheng et al. 2018), using national datasets. We applied the HAND-SRC methodology using Python and open-source global datasets, to create continental-scale flood risk maps for Europe and the US.  The use of open-source global datasets and Python means the method has the potential to be applied anywhere globally.  
How do moisture changes influence root-derived methane cycling in wetland soils?
Authors: Malhotra Avni , Määttä Tiia , Hertel Nadja , Sriskandarajah Nijanthini , Schiedung Marcus , Wüst-Galley Chloé , Abiven Samuel , Heller Sandra , Leifeld Jens , Schmidt Michael , Tumber-Dávila Shersingh
Published: February 2023

Anoxic wetland soils are the biggest natural source of methane (CH4) globally. Climate-driven changes to soil moisture regimes are expected to alter wetland CH4 production, consumption, and transport in a variety of different ways. At the same time, moisture changes also influence plants and their traits, especially belowground. Wetland plants provide key carbon substrates for methanogenesis, and transport CH4 to the atmosphere but also oxygen into the soils, which can promote CH4 consumption. We tested hypotheses on these complex abiotic and biotic interactions to understand how belowground plant traits influence net CH4 emissions in wetlands. Specifically, we address the following questions 1) which root traits are most important for wetland CH4 processes? 2) how does water table manipulation influence the link between root biomass and CH4? 3) how does soil moisture influence the amount of root-derived carbon emitted as CH4? First, using a literature review, we developed a conceptual framework describing root traits that would be most related to CH4 processes, highlighting trait categories regulating CH4 substrate provision and transport. Second, using a field manipulation in an experimental rice system, we found that root biomass and CH4 emissions are positively linked, but only under low moisture conditions. Lastly, in a lab incubation, we found that the amount of root-derived C-CH4 increases with increased fresh root litter, in water saturated peat soils. Overall, our studies identify root traits and their moisture interactions that should be considered in wetland CH4 measurements and models.
Miniaturized wave measurement drifter for undersatellite calibration and validation network
Authors: Charron Lucas , Mironov Alexey
Published: February 2023

As the number of satellite missions observing the ocean increases, reliable and cost-efficient tools are needed to accurately calibrate and validate the expanding network of space sensors. Traditionally, sea surface buoys have been used to measure various oceanic and atmospheric parameters; however, when it comes to subsatellite data related to processes occurring in the upper ocean layer, the use of traditional buoys is not always straightforward. The properties of different sensing bands, acquisition rates, sensor time and spatial resolution must be taken into account to properly match satellite remote signals with in-situ buoy measurements. This necessitates the creation of specialized sensors dedicated to measuring sea surface parameters, such as directional wave spectrum, sea surface current, and temperature, that have the most significant impact on remote sensing signal formation.The Miniaturized Electronics Lagrangian Oceanographic Drifter (MELODI) program has developed a specialized electronic platform that enables the rapid construction of miniaturized, cost-effective sea surface drifters for subsatellite calibration/validation tasks. The hardware can be configured with different set of onboard sensors, data preprocessing/compression modules, and satellite-enabled communication systems to allow for the real-time collection and transmission of data. Preference is given to the extensive use of environmental-friendly and biodegradable materials, as well as to the implementation of an industrial fabrication process to reduce the time and costs of mass buoy production.Our study addresses the specificity of measurements obtained from small-scale platforms, such as directional wave spectrum distortions due to intrinsic noise, reduction of wind impact on the buoy drift, oceanographic data preprocessing and compression for IOT small satellite messaging, etc. We present the first results of an in-situ validation campaign (7 day long) for a buoy created specifically for cal/val of the Surface Water and Ocean Topography (SWOT) mission. This miniaturized drifter (~15 cm in diameter) has onboard accelerometers, gyroscopes, magnetometer, GPS sensors and is dedicated to the systematical measurement of significant wave height, directional wave spectrum and sea surface current. The satellite-based communications allow real-time reporting every 15 min, with an expected autonomy of 2 months up to 1 year depending on the configuration and reporting frequency.We expect that the present results,  electronic platform, and proposed algorithmic and technical solutions will allow enabling the development and implementation of a more robust network of observational drifting buoys for calibration and validation of ocean monitoring satellite missions. The work was supported by the project “Development of marine services using space data and IOT technologies by Kinéis” funded by IFREMER and Kinéis.
Indicator Kriging approach for the assessment of groundwater nitrate pollution in the Salento aquifer (Southern Italy)
Authors: Fiorese Gaetano Daniele , Alfio Maria Rosaria , Balacco Gabriella
Published: February 2023

Groundwater, being the largest distributed freshwater supply, plays a central role in sustaining ecosystems and enabling human adaptation to climate change. The strategic importance of freshwater for global water and food security will intensify as the frequency of extreme weather events such as floods and droughts events. Many aquifers are severely stressed due to unsustainable management of the water resource that compromises its quantity and quality.Today, nitrate pollution is the most common form of groundwater contamination worldwide. Many Mediterranean regions present worrying concentrations of nitrate in groundwater and are consequently one of the most polluted territories across the world. Nitrate monitoring is fundamental since excessive concentrations in water resources may affect the quality of crops and causes several human health disorders. For this purpose, this study aimed to deal with the evolution in space and time of nitrate concentrations in the coastal karst aquifer of Salento (Puglia, Southern Italy), whose water demand for drinking and irrigation purposes relies on groundwater. The intrinsic vulnerability of this territory is critical due to its complex geomorphological and structural characteristics, the presence of saltwater beneath freshwater, intensive exploitation, and climate change.Several different chemical surveys from 1995 to 2021 were organized into two-time datasets to focus on the spatio-temporal evolution of nitrate concentrations. The geostatistical Indicator Kriging (IK) method was used for this purpose. This is a spatial interpolation technique aimed at estimating the conditional cumulative distribution function of a variable at an unsampled location. Indicator Kriging analyses were performed for a direct estimation of the local conditional probabilities of nitrate concentrations for the two reference periods using sampled available wells. Probability maps representing the spatial distribution of water quality have been obtained as result. Results highlight a critical situation in terms of nitrate pollution, as most of the territory has experienced an increase over the past 25 years, progressively affecting large areas.
Bedmap3: new data and gridded products of Antarctic ice thickness, surface and bed topography
Authors: Fremand Alice , Pritchard Hamish , Fretwell Peter , Bodart Julien
Published: February 2023

We present Bedmap3, the first comprehensive and openly available compilation of Antarctic Ice Sheet survey datasets, plus the latest gridded mapping products of ice thickness and the surface and bed topography of the whole Antarctic continent and continental shelf. For 60 years, scientists have strived to understand the past, present and future of the ice sheet, a goal that has become ever more urgent as ice loss accelerates. Key to this research has been the mapping of the bed-topography, surface slope and ice-thickness parameters that are crucial for modelling ice flow, and hence for predicting future ice loss and ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR) and data contributions from the international survey community, the Bedmap3 Action Group has now produced substantially updated gridded maps of these parameters and, for the first time, has standardized and made available all underlying geophysical survey data points from all Antarctic ice-thickness survey campaigns since the 1950s. Here, we describe the standardization that makes these and future datasets accessible under the ‘Findable, Accessible, Interoperable and Reusable’ (FAIR) data principles, allowing scientists to re-use these data freely for their own analysis. We also describe the results of our new mapping, and how this changes our view of Antarctica’s hidden landscapes and its potential to dominate future sea level rise.
Heating response patterns of Alpine soils: from a plot-scale to lab experiments.
Authors: Negri Sara , Giannetta Beatrice , Mantero Giulia , Stanchi Silvia , Marzano Raffaella , Garbarino Matteo , Celi Luisella , Bonifacio Eleonora
Published: February 2023

Wildfires play the role of ecosystem shapers in the majority of terrestrial biomes. Nowadays, their regimes are changing as a consequence of land abandonment and climate change. After-fire dynamics are widely studied in North America and Mediterranean environments. However, soils developed in different biomes might not unequivocally respond to fire-induced heating, and forests of the Western Italian Alps are not unfamiliar to fire occurrence.For these reasons, we conducted several experiments (at plot and lab scale) at environmentally realistic conditions to systematically assess the impacts of fire on the physico-chemical properties of soils belonging to the Italian Alpine ecological region.A homogenous pine forest (Pinus sylvestris L.) located in a mountain region near Torino experienced the passage of a severe and large wildfire in fall 2017. The field survey carried out in 2020 revealed that lower organic carbon (OC) contents and higher bulk density (BD) values were associated to a greater fire severity. Abundance of pyrogenic carbon was related to the steepness degree, as a consequence of erosion. In the superficial horizons, the naturally high WR expected from soils developed under a conifer stand was not present.To elucidate mechanisms regulating WR occurrence and evolution, the thermal transformations borne by Alpine soils were investigated at controlled laboratory conditions. Topsoil samples displayed extremely different wettable behaviors upon increasing temperatures (Ts), with or without WR build-up. This occurred mainly in relation to content and composition of organic matter (OM), particle size distribution and abundance of iron (Fe) oxides. Notwithstanding the initial sample hydrophobicity, WR was dramatically lost above 200 °C due to increasing pH values, inducing OM de-sorption from the negatively charged mineral surfaces.In the same T range, the thermal transformation of soil Fe oxides were found to be primarily directed towards oxidative processes (hematite formation). Ts up to 300 °C could have potentially promoted the stabilization of the remaining (non-combusted) OM, with the synthesis of defect-rich Fe oxides and enrichment in condensed and aromatic compounds, and yet OM was highly dispersible at the high pH values resulting from the thermal treatment, such that OC might be weakly retained on mineral phases in an after-fire scenario.
Elevated ammonia emission neutralized alleviation of nitrogen deposition to water pollution in China
Authors: Feng Sijie , Xu Wen , Wang Mengru , Zhao Yuanhong , Strokal Maryna , Kroeze Carolien , Ma Lin , Zhang Fusuo
Published: February 2023

Over the past few decades, human activities associated with energy and food production (e.g., industrial, traffic, agricultural, and waste disposal sources) have substantially increased emissions of reactive nitrogen (Nr) to the atmosphere which leads to excessive atmospheric nitrogen (N) deposition on land and rivers. Part of the deposited N on land is also transported to rivers (defined as indirect N deposition). China is a global hotspot of N deposition and has implemented strict atmospheric policies in the last decade. Yet, the responses of N deposition (including direct and indirect N deposition) to these policies and inputs into the river are not well known. We couple a global chemistry transport model with the native 0.5°×0.625° horizontal resolution with a water quality model to simulate direct and indirect N deposition from human activities on rivers in 33 Chinese sub-basins in 2011 and 2019. Compared with 2011, the fluxes of direct N deposition on both rivers and land changed from 10.9 to 10.8 Tg N yr-1 (including deposition of reduced nitrogen (NHx) changed 4.6 to 5.9 Tg N yr-1 and deposition of oxidized nitrogen (NOy) changed 6.3 to 4.9 Tg N yr-1) among the sub-basins in 2019. The results indicate that the strict air policies since 2013 released by the Chinese government significantly decreased NOy. However, the amounts of direct and indirect N deposition on water on average only declined by 2% across all sub-basins, mostly due to the increases in dry ammonia deposition. Agriculture was estimated as the largest source, contributing 30% and 37% to the total N deposition in 2011 and 2019. Thus, agricultural ammonia emission control is essential to reduce N deposition-induced water pollution. This integrated air-water model can assess the impacts of N deposition on water quality, providing insights to develop the pollution control policy for both air and water in sub-basins.
Plant and soil biodiversity is essential for supporting highly multifunctional forests during Mediterranean rewilding
Authors: Zhou Guiyao , Lucas-Borja Manuel Esteban , Liu Shengen , Delgado-Baquerizo Manuel
Published: February 2023

The multidimensional dynamics of biodiversity and ecosystem function during the rewilding of Mediterranean forests remain poorly understood, limiting our capacity to predict how future restoration efforts may help mitigating climate change. Here, we investigated the changes in multiple dimensions of biodiversity and ecosystem services in a 120-year forest succession after harvest to identify potential trade-offs in multiple dimensions of ecosystem function, and further assess the link between above and belowground biodiversity and function. We found a positive influence of successional age on multiple dimensions of biodiversity and function, but also some important trade-offs. Two ecosystem axes of function explained nearly 75.4% functional variation during ecosystem rewilding. However, while the first axis increased with successional age promoting plant productivity and element stocks, the second axis followed a hump-shaped relationship with age supporting important reductions in nutrient availability and pathogen control in old forests. Our study further revealed that a significant positive relationship between plant and soil biodiversity with multiple elements of multifunctionality as forests develop. Moreover, the influence of plant and soil biodiversity were especially important to support a high number of function working at high levels of functioning. Our work provides new insights on the patterns and functional trade-offs in the multidimensional rewilding of forests, and further highlight the importance of biodiversity for long-term Mediterranean rewilding.
Use of UAVs for geological risk management and analysis: The case study of the mud volcano of Villaggio Santa Barbara, Caltanissetta (Sicily).
Authors: De Guidi Giorgio , Brighenti Fabio , Carnemolla Francesco , Giuffrida Salvatore , Messina Danilo , Monaco Carmelo
Published: February 2023

Deformation effects on surface due to active geological processes are several (e.g., uplift, subsidence and shear discontinuities), these are strictly related to the source parameters and to the geomechanical properties of the surrounding rocks. In the last 20 years, remote sensing represents a key tool for the evaluation and monitoring of the natural hazards. Disasters occur when hazard and vulnerability match.
The risk is proportional to the magnitude of the hazards and the vulnerability of the involved population. Among the deformation monitoring systems, photogrammetry technique from Unmanned Aerial Vehicles (UAVs) is spreading thanks to the high efficiency in data acquisition (time span, resource, and operators), low cost and the capability to acquire high-resolution images. The use of UAVs in contexts of natural hazard presents three main steps for risk assessment: pre-post event data acquisition, emergency support and monitoring. The mud volcano of Santa Barbara (Municipality of Caltanissetta, Sicily, Italy) represents a potentially dangerous site. On 11th August 2008 a paroxysmal event caused serious damage to infrastructures for a range of about 2 km. The main clues of mud volcano paroxysmal events are the uplift and the development of structural features with dimensions ranging from centimetre to decimetre. Here we present a methodology for monitoring of deformation processes that may be precursors of the mud volcano unrest period. This methodology is based on: i) the data collection, ii) the Structure from Motion (SfM) processing chain and iii) the M3C2-PM algorithm for the comparison between point clouds and uncertainty analysis with a statistical approach. This methodology is useful to detect hazard precursors by monitoring of deformation processes with centimetre precision and a temporal frequency of 1 - 2 months. Precision maps and the M3C2-PM algorithm are used to determine surface variations. The statistical analysis allows us to verify i) the uncertainty between the different surveys ii) the spatial variability of the accuracy; iii) the quality of the georeferencing of the surveys based on the number of GCPs (ground control points).
Phase transition induced stresses and their implications for deep earthquakes
Authors: Thielmann Marcel , Aharonov Einat , Yamato Philippe , Duretz Thibault
Published: February 2023

The nucleation and rupture processes of deep-focus earthquakes have remained enigmatic ever since their discovery. These earthquakes occur mostly within the mantle transition zone where brittle failure is extremely unlikely due to the elevated pressures at these depths. Hence, other mechanisms have to be invoked to explain the occurrence of these events. To date, two main hypotheses have been put forward to explain deep focus earthquakes: transformational faulting (due to the polymorphic phase change of metastable olivine to either wadsleyite or ringwoodite) and thermal runaway (due to the conversion of deformational work to heat). More recently, it has been proposed that the feedback between those two mechanisms may explain the observed two-stage ruptures of large deep-focus earthquakes.To better understand the potential feedback between transformational faulting and thermal runaway, it is necessary to determine the stresses induced by the phase change due to i) the grain size reduction and corresponding viscosity reduction of the transformed material and ii) the volume reduction of the transformed phase. The former process triggers a stress transfer from the transformed material to the untransformed material, whereas the latter results in elevated stresses around the transformed phase.In this study, we employ numerical models with a viscoelastic compressible rheology to quantify the stress levels and patterns resulting from both processes. To gain a better understanding of the parameters controlling the stress transfer from transforming regions to the surrounding matrix, we employ simplified numerical models where transforming regions are approximated using elliptical inclusions. In a second step, more realistic model geometries are used to additionally study the effect of the morphology of transformed regions on stress levels and heterogeneities.Results show that both processes result in significantly different stress evolution upon a phase transition. Whereas a phase transition affecting only the viscosity of the transformed material results in moderate stress increases which occur on relatively long timescales, a phase transition affecting both viscosity and density results in significantly larger stresses, which also exhibit a significantly faster build-up. In both cases, the attained stress are sufficiently large to activate additional ductile weakening mechanisms that could trigger ductile ruptures. The higher stress levels resulting from the combined effect of a viscosity and density change would likely result in stronger weakening effects and faster occurrence of ductile failure.
Climate projections of frost risk for apple (Malus Domestica) in Slovenia
Authors: Žnidaršič Zala , Sušnik Andreja , Gregorič Gregor , Pogačar Tjaša
Published: February 2023

Due to climate change and increasing temperatures, the phenological development of fruit trees is expected to advance, which already results in higher susceptibility of fruit trees to crop-destroying spring frosts due to phenological stages of bud break or flowering occurring too early in the year. An assessment of the risk of tardive frosts for apple (Malus domestica) in Slovenia was made throughout the 21st century from temperature data of 6 climate model projections, specifically from regionally downscaled projections data of the EURO-CORDEX. The first part of the analysis was based on two phenological models - a classic GDD model and a two-phased BRIN model. In the second part of the analysis the conditional probability of frost occurrence was calculated from the statistical probability of the last day with frost conditions and the budburst event probability, as simulated by the chosen phenological models. The results showed that the probability of frost events occurring after flowering in Slovenian apple varieties increases throughout the 21th century in the case of the RCP4.5, as well as the RCP8.5. We identified the period of 2071–2100 as the period when the majority of Slovenian apple-growing regions will be most prone to frosts, whereas during 2011–2040 and 2041–2070 the probability of frost occurrence might vary. This work was supported by the Slovenian Research Agency, Research Program P4−0085.
Synoptic- to meso-scale circulation connects fluvial and coastal gravel conveyors and directional deposition of coastal landforms in the Dead Sea basin
Authors: Eyal Haggai , Armon Moshe , Enzel Yehouda , G Lensky Nadav
Published: February 2023

Streams convey coarse-clastic sediments towards coasts, where interactions with deltaic and coastal processes determine the resultant landscape morphology. Although extracting hydroclimatic signals from landscapes is a desired goal, many studies rely on interpreting paleoclimatic proxies and the link between depositional/geomorphic processes and the hydroclimate remains vague. This is a consequence of the challenge to link processes that often are studied separately, span across large spatial and temporal scales including synoptic-scale hydroclimatic forcing, stream flows, water body hydrodynamics, fluvial and coastal sediment transport, and sedimentation. Here, we explore this chain of connected processes in the unique setting of the Dead Sea basin, where present-day hydroclimatology is tied closely with geomorphic evolution and sediment transport of streams and coasts that rapidly respond to lake-level fall. We use a five-years-long (2018-2022) rich dataset of (i) high-resolution synoptic-scale circulation patterns, (ii) continuous wind-wave and rain-floods records, and (iii) storm-scale fluvial and coastal sediment transport of varied-mass, ‘smart’ and marked boulders. We show that Mediterranean cyclones approaching the eastern Mediterranean are the main circulation pattern that can provide sufficient rainfall and winds that concurrently activate two perpendicular sediment conveyors: fluvial (floods) and coastal (wind-waves). The synoptic-scale westerlies (>10 m s-1) are orographically funneled inside the Dead Sea rift valley, turning into surface southerlies. They generate 10-30 high-amplitude northward propagating storm waves per winter, with <4 m wave height. Such storms transport cobbles for hundreds of meters alongshore, north of the supplying channel mouths. Towards the decay of the storm wave, the high-altitude synoptic westerlies provide moisture to generate 4-9 flash-floods, delivering unsorted coarse gravels into the basin. These gravels are dispersed alongshore by waves only during subsequent storms. As storm waves dominates and are >five times more frequent than flash-floods, coarse-clastic beach berms and fan-deltas are deposited preferentially north of channel mouths. This depositional architecture, controlled by regional hydroclimate, is identified for both the modern and Late Pleistocene coast and delta environments, implying that the dominance of present-day Mediterranean cyclones has persisted in the region since the Late Pleistocene when Lake Lisan occupied the basin.
Mapping fire susceptibility in Portugal
Authors: Gouveia Célia , Ermitão Tiago , Trigo Isabel F. , Páscoa Patrícia
Published: February 2023

Southern Europe is considered a fire-prone region, and fire events occur here every summer. In this context, large fires have hit Portugal over the last 20 years, due to frequent hot and dry summer conditions, and also to high fuel availability in ecosystems. Moreover, climate change in the Mediterranean basin is expected to increase the severity of fire weather conditions and therefore to increase the occurrence of extreme fire seasons.
Recent catastrophic fire seasons have led to the implementation of a set of policies during the months before the fire-season, aiming at fire prevention and suppression, which can in turn increase the combat efficiency of fires during the fire season. Therefore, this work intends to contribute to fire prevention by identifying regions with a high likelihood to burn.
A Principal Components Analysis (PCA) was applied to several climatological, ecological, and biophysical variables, related to fire weather, fuel availability, and elevation covering the period from 2001 to 2021. Results allowed to assess the areas where large fires were more likely to occur in 2022. The central and southernmost regions of Portugal showed a stronger signal in the PCA, indicating a likely high susceptibility to future fire events. The association of fuel accumulation since the last fire event with elevation and favourable fire weather conditions explains most of the variability of the first six PCs. These results were compared with the fires that occurred in 2022, and a match between larger burned areas and high signals in the PCA was found, highlighting the usefulness of this methodology.
This study was supported by FCT (Fundação para a Ciência e Tecnologia, Portugal) through national funds (PIDDAC) – UIDB/50019/2020, and under the projects FlorestaLimpa (PCIF/MOG/0161/2019).
Unveiling the turbulence scale couplings in fluctuating time series during EUREC4A
Authors: Gauvrit Edouard , Bouin Marie-Noelle , Delouis Jean-Marc , Boulanger François
Published: February 2023

Inside the Marine Atmospheric Boundary Layer (MABL) turbulence drives a large amount of physical processes through a dynamical coupling. Understanding this coupling is a key issue in weather and climate modeling, but an adapted statistical representation is still lacking. A strong limitation comes from the non-Gaussianities existing inside the MABL. We seek an approach to describe statistically the couplings across scales, which is poorly measured by the power spectrum. Recent developments in data science provide new tools as the Wavelet Scattering Transform (WST), which gives a low-variance statistical description of non-Gaussian processes and offers to go beyond the power spectrum representation.We proposes to apply WST technique on turbulent moments recorded during the EUREC4A campaign in trade-wind cloud regimes. Using WST analysis on both fluctuating time series and realistic Large-Eddy Simulations (LES), we study how the different scales in turbulent flows interact between each other in the MABL. Are the turbulent flows organised or purely random in the MABL ? Do the couplings change for different cloud organisations ? Do the models show evidence of such scale couplings ?In this presentation, we first look at the expected WST coefficients law for turbulent flows in the inertial subrange. Second, we present what are the WST coefficients for the measured turbulent moments and how they evolve for different cloud organizations.
Hydrogen storage pilot: geological characterisation of an onshore aquifer structure in Fife, Scotland
Authors: Adie Kate , Heinemann Niklas , Papageorgiou Giorgos , Wilkinson Mark , Haszeldine Stuart , Thompson Colin , West Courtney
Published: February 2023

Energy storage technologies are required to support the rapid development and integration of intermittent renewable energy sources into energy systems. Large-scale hydrogen storage in porous formations presents the opportunity to balance seasonal variation in energy demand. This reservoir modelling study aims to establish dynamic capacity estimates for seasonal hydrogen storage. This study investigates a shallow (<1km) sandstone reservoir, of an onshore anticlinal structure in east Fife, Scotland. This storage evaluation supports the geographically proximal H100 pilot rollout of 100% hydrogen for domestic use in 300 volunteer homes (https://www.sgn.co.uk/H100Fife). The target reservoir comprises a partially explored Carboniferous aquifer, thus this study also addresses the challenge of establishing a workflow for the appraisal of storage sites with limited data availability. We aim to maintain low investment costs for this currently immature technology. A static 3D geological model was constructed in reservoir modelling software, PETREL (Schlumberger), informed by data obtained from legacy seismic surveys and from deep boreholes acquired in a hydrocarbon exploration campaign in the 1980s. A sedimentological study was undertaken on the well-known local and regional Carboniferous sedimentology from subsurface information and coastal exposures to characterise reservoir heterogeneity internally – a necessary step to address the large data gaps between sparsely available data points. The reservoir is conceptualised as a 60-70m channelised fluvial sand, with unreactive quartz-arkose mineralogy, interbedded with thin mudstone horizons. The top seal is characterised by silts and mudrock, comprising a widespread maximum flooding surface. Seismic and borehole data has enabled a 3D base case model of stratigraphy and structure. Combined reservoir and structure forms a finite element model exported to CMG’s GEM, used to assess dynamic capacity estimates. Our key research questions are: does the target reservoir exhibit sufficient capacity to support seasonal hydrogen storage based on scenarios informed by industrial experience; what are the cushion gas requirements and associated costs; and what are the key risks and uncertainties influencing capacity estimates. We plan a base case scenario using the most probable geological reservoir and will investigate sensitivity variations around the geology. Benefits from this study include: i) development of a workflow for the hydrogen characterisation of storage reservoirs and the management of risk, whilst minimising initial investment costs, ii) evaluation of cushion gas requirements in a layered reservoir with only a few degrees of dip. Our preliminary results of injection and production will be discussed.
Analysis of a 23-years Long Eddy-covariance Fluxes Dataset from a Mixed Deciduous Forest in Germany
Authors: Klosterhalfen Anne , Fellert Dietmar , Koebsch Franziska , Kreilein Heinrich , Markwitz Christian , Mund Martina , Peksa Marek , Tiedemann Frank , Tunsch Edgar , Knohl Alexander
Published: February 2023

In this study, we present the 23-years long dataset (2000-2022) provided by the flux tower site (DE-Hai) in the National Park Hainich, Thuringia, in Central Germany. Next to eddy-covariance flux measurements comprehensive datasets of meteorological and environmental conditions (e.g., soil respiration, leaf area index) were obtained over the last two decades. These long-term datasets represent the land-atmosphere interactions and their feedback with average and several extreme meteorological conditions, and thus provide the opportunity to investigate the resilience of this old-growth deciduous forest against extreme events.The diel, daily and annual cycles of net ecosystem CO2 exchange, latent and sensible heat fluxes are presented. Further ecosystem functions, such as Bowen ratio and water use efficiency, are analyzed. Footprint analysis revealed that the fluxes originated for > 95% from the mixed deciduous forest and that the main source region is located within 0.5-1 km around the tower. However, the source area differs slightly between day- and nighttime. The deciduous forest was a large and persistent net carbon sink, with an annual net ecosystem exchange between -339 and -670 g C m-2. Environmental drivers of the ecosystem flux exchange were identified based on statistical analysis. A large uncertainty was introduced to flux estimates due to the applied post-processing methods (e.g., gap-filling), and strong impacts of recent drought events were observed for the flux exchange during and after the events. Moreover, the interrelationship between tree growth estimates based on circumferences of individual trees and eddy-covariance fluxes on ecosystem-level were investigated. Discrepancies between the carbon sink estimates on tree- and ecosystem-level are discussed.
The Effect of Spatial and Cross-Profile Data on Morphodynamic Modelling
Authors: Siedersleben Jakob , Jocham Stefan , Klar Robert , Aufleger Markus
Published: February 2023

Morphodynamic modelling relies on different types of riverbed surveys. Surveys are essential as the basis of the evaluation of temporal river bed development, mesh creation, and model calibration. Spatial data, for example, obtained by topo-bathymetric airborne laser scanning (ALB) or sonar surveys results in a dense point cloud, providing detailed information on the river bathymetry. However, data gaps can occur due to restrictions in data acquisition (e.g. high water turbidity or water depth for ALB, low water for boat-mounted sonar). In contrast, cross-profiles contain only limited information on the bathymetry strongly dependent on the cross-profile and point spacing.To assess the effect of the two survey data types on river bed development and morphodynamic predictions, the temporal evolution of a river stretch in the upper Danube at Donauwörth was analysed. The study area contains homogeneous river sections and sections with complex river geometry due to scours, bridge foundations, and river mouths.  Spatial sonar and ALB surveys were conducted from 2013 to 2020 and give detailed documentation of the river bed development. Cross-profiles with a cross-profile spacing of 200 m were derived from the spatial data. The spatial and cross-profile datasets show continuous river bed erosion. However, in this case, cross-profile data overestimate the overall erosion compared to spatial data. The geometry of homogeneous river stretches is depicted very similarly in the two datasets. For cross-profile data two cases exist for reaches with more complex river bed geometry: (i) The geometry lies in between two cross-profiles and it is missed entirely. (ii) The geometry is covered by a cross-profile and the resulting geometry is smeared in between the cross-profiles due to the interpolation process. Both possibilities result in an unsatisfactory depiction of the riverbed geometry.To analyse the effect of morphological developments two morphodynamic models based either on the spatial or cross-profile datasets were set up. The models were calibrated against the datasets from 2013 to 2020 by adjusting the Strickler value for river sections with a length of 200 m. The Strickler values differ over the entire river stretch and not only in sections where complex river bed geometry occurs, meaning that the calibration errors propagate through the entire study area. Consequently, the deviations in calibration outcomes affect the model predictions, which simulate 7 years. In this case, the general shape of the predicted riverbed is similar, but due to the overestimation of riverbed erosion by cross-profile data, the morphodynamic model overestimates the erosion compared to the spatial data. However, the obtained error is for river reaches with low local variability within an acceptable range. If a project demands a highly accurate depiction of the river bed and the river geometry is known for having complex features, the use of spatial data is strongly advised.