bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating the impact on water fluxes and physiological development of the combination of contrasted root wheat cultivars from isotopic analysis
Authors: le Gall Samuel , van Duschoten Dagmar , Lattacher Adrian , Giraud Mona , Harings Moritz , Deseano Diaz Paulina , Sircan Ahmet , Poll Christian , Lobet Guillaume , Javaux Mathieu , Rothfuss Youri
Published: March 2024

Farmers are increasingly adopting practices that add more biodiversity to agro-ecosystems for improving crop yield level and stability. These practices include co-croping, that is the cultivation of different phenotypes (or cultivars) in the same field. However, we are missing clear criteria for the selection of the cultivars as well as a quantified assessment of the effect of the combination on water use and partitioning.In our study, we proposed to focus on the association of two wheat cultivars having contrasted root systems. We further aimed at evaluating the effect of such an association on water flow by monitoring root water uptake vertical patterns from isotopic analyses.In a control environment, we ran experiments on soil columns (silty-clay) (diam=11cm, height=80cm) each planted with two wheat cultivars (“shallow-rooted” vs “deep-rooted”) until ear emergence. Six different modalities were tested, i.e., 3 crop types (2 shallow-rooted individuals / 2 deep-rooted individuals / combination of 1 shallow-rooted individual and 1 deep-rooted individual) x 2 treatments (well-watered conditions or water stress). We repeated the experiment six times to test all the different modalities mentioned above in triplicate. Profiles of root water uptake (RWU) relative fractions were statistically evaluated (with a Bayesian mixture model) at cm to dm vertical resolution from soil water and transpiration flux isotope data non-destructively using gas-permeable membranes and gas chambers coupled to a laser spectrometer. Plants were also monitored physiologically during the experiment (e.g., leaf area, chlorophyll content, root architecture by magnetic resonance imaging) and destructively (e.g., above-ground and below-ground biomass, root area, stomatal density).We will present our observations on how the RWU profile are affected by soil water status, wheat phenotype and associated plant identity. Surprisingly, the deep-rooted phenotype individuals - which uptake more water than the shallow-rooted individuals at soil depth between 40cm and 80cm under water deficit condition - are also the most physiologically sensitive (reduction in leaf area, significant change in shoot/root biomass ratio) at the first reproductive stages. On the field scale, this could have later a negative impact on the yield of the deep-rooted phenotype monoculture, but this should be moderate in co-cropping situations, where the sensitivity of the whole is lower.
An operational framework for improving the resilience of inland waterways and floodplains to the impacts of flood-induced dike breach hazard
Authors: Dewals Benjamin , Hardy Joris , Mastricci Davide , Schmitz Vincent , Melitsiotis Alexis , Pirotton Michel , Erpicum Sébastien , Archambeau Pierre
Published: March 2024

Early warning is critical to enhance the resilience of communities and infrastructures towards a wide range of natural and human-caused hazards. As a part of a broader initiative aiming at improving the resilience of waterways to multi-hazards risk (earthquake, fog, wind, low flow …), we present here components of an operational hazard assessment tool focusing on the impact of dike breaching. The system is developed and showcased on a study site located in Belgium, involving major waterways such as a stretch of river Meuse, a parallel navigation channel and tributaries.The modelling strategy builds on three steps. Step one is a machine-learning-based hydrological model which provides quick estimates of flow rate at the upstream ends of the domain. The model was trained based on observed flow rates and precipitation data at rain gauges distributed across the catchments.Step 2 consists in a detailed hydrodynamic modelling reproducing the flow in the navigation channels and simulating breach development, flow through the breach, as well as in the floodplains. This approach is accurate and detailed; but too slow for rea-time prediction, i.e., operational use. Therefore, Step 3 consists in combining a quick and efficient simplified dike breach model to estimate breach hydrograph and produce inundation maps in the floodplains by spatial interpolation in a collection of pre-computed results of the detailed hydrodynamic model (Step 2).The model structure will be detailed, and results will be presented and discussed.This research is co-funded by the European Union’s Horizon Europe Innovation Actions under grant agreement No. 101069941 (PLOTO project: https://ploto-project.eu/). 
Controls on high precision zircon U-Pb age spectra in magmatic systems
Authors: Nathwani Chetan , Tavazzani Lorenzo , Szymanowski Dawid , Virmond Adrianna , Markovic Sava , Chelle-Michou Cyril
Published: March 2024

U–Pb and U–Th geochronology of zircon in igneous rocks provides key information about the age, longevity, and assembly rates of magma reservoirs. Historically, the available analytical resolution limited these insights to an averaged “age” of a magmatic system. With dramatic improvements in analytical techniques over the last two decades, it has become possible to resolve extended records of zircon crystallisation within a single igneous sample, which can extend prior to its eruption or subsurface solidification by as much as a million years. In some magmatic systems these age spectra mirror those produced in zircon solubility models, reflecting monotonous cooling of a magma reservoir, whilst in others they may take other shapes indicative of a more complex interplay of processes [1,2]. Isolating the effect of these processes can be challenging since many analytical and geological factors also play a role. Such geological processes may include magma recharge or truncation of zircon crystallization by melt extraction.In this study, we compiled high-precision zircon U-Pb dates from volcanic, plutonic and porphyry copper systems. We use the Wasserstein metric as a dissimilarity measure to compare distributions between all compiled age spectra. Dimensionality reduction of the resulting dissimilarity matrix reveals that plutonic systems have contrasting age spectra to volcanic and porphyry copper systems. Plutonic systems typically exhibit age spectra skewed towards older ages whereas volcanic and porphyry systems are skewed towards younger ages.We adopt a bootstrap modelling approach to explain these differences, which allows the modelling of the effects of the number of sampled zircons, analytical uncertainties, magmatic recharge, mixed age domains and a truncation of crystallisation. The effects of multiple magmatic recharge events combined with truncation by volcanic eruption/dyke formation appear to be the most likely explanation for the young skew of volcanic and porphyry copper age spectra. Truncation of zircon crystallization alone appears to be incapable of explaining the full difference. Recognising the contrasting zircon age spectra between volcanic and plutonic systems is critical to improve eruption age estimation and interpretations of zircon compositions in petrological studies.[1] Keller, C.B., et al., GPL, 2018. 31–35.[2] Tavazzani, L., et al., EPSL, 2023. 623, 118432.
Improving real-time GNSS precise point positioning convergence with open ECMWF HRES forecast data
Authors: Wu Peida , Lou Yidong , Zhang Weixing
Published: March 2024

High-accuracy tropospheric delay correction is the key of Real-Time (RT) GNSS PPP of fast convergence. In daily RT PPP apllicaitons, the empirical tropospheric models, such as GPT, GPT2 and GPT3, are commonly-used for the correction, and the correction accracy is no ideal (3-5 cm). Besides the empirical model, the forecast numerical weather model also can be used for the correction, and the correction accracy depends on the model resolution and forecast duration. In year 2022, ECMWF released the high-resolution forecasts (HRES) numerical weather model data, wich can be one good alternative of the empirical model for better correction, considering its global coverage and high-resolution. In this contribution, we evaluated the HRES derived ZTD accuracy by taking the GNSS ZTD as reference and compared with GPT3 at global distributed stations. The accuracy of HRES ZTD will be higher than that of the GPT3 model. We also analyzed the RT PPP performance by adopting the HRES ZTD and GPT3 ZTD as a priori constraint. The HRES ZTD will accelerate the RT-PPP convergence.
Recalibrating DWD’s operational climate predictions: towards a user-oriented seamless climate service
Authors: Pasternack Alexander , Mannig Birgit , Paxian Andreas , Hoff Amelie , Pankatz Klaus , Lorenz Philip , Früh Barbara
Published: March 2024

The German Meteorological Service's (Deutscher Wetterdienst DWD) climate predictions website  (www.dwd.de/climatepredictions) offers a centralized platform for accessing post-processed climate predictions, including subseasonal forecasts from ECMWF's IFS and seasonal and decadal predictions from the German climate prediction system. The website design was developed in collaboration with various sectors to ensure uniformity across all time frames, and users can view maps, tables, and time series of ensemble mean and probabilistic predictions in combination with their skill. The available data covers weekly, 3-month, 1-year, and 5-year temperature means, precipitation sums and soil moisture for the world, Europe, Germany, and particular German regions. To achieve high spatial resolution, the DWD used the statistical downscaling method EPISODES. Moreover, within the BMBF project KIMoDIs (AI-based monitoring, data management and information system for coupled forecasting and early warning of low groundwater levels and salinisation) the DWD provides climate prediction data of further hydrological variables (e.g. relative humidity) with corresponding prediction skill on a regional scale.However, all predictions on these time scales can suffer from inherent systematic errors, which can impact their usefulness. To address these issues, the recalibration method DeFoReSt was applied to decadal predictions, using a combination of 3rd order polynomials in lead and start time, along with a boosting model selection approach. This approach addresses lead-time dependent systematic errors, such as drift, as well as inaccuracies in representing long-term changes and variability.This study highlights the improved accuracy of the recalibration approach on decadal predictions due to an increased polynomial order compared to the original approach, and its different impact on global and regional scales. It also explores the feasibility of transferring this approach to predictions with shorter time horizons of the provided variables.
Internal structure inference of lunar lave tubes with the MCMC approach
Authors: Wang Wenrui , Jiang Xingda
Published: March 2024

For decades searching for the safe habitation site on the moon have piqued the interest of researchers. Safe habitats should be resilient under different hazards including radiation, temperature fluctuation, and meteorite impacts. The natural tunnels on the Moon called “lava tubes” are considered as good candidates for permanent human shelters. Their hard basaltic roof may provide increased safety from different hazards, and their width can be as large as ~1-2 km, promising the underground storage with little construction effort.
Lying beneath the surface, the lava tubes cannot be detected by surface imagery or altimetry, although close association with known rilles, skylights, or rimless pits may add credibility to a potential candidate. However, linear lower magnitude of gravity data indicates the subsurface density deficits and provide another piece of evidence supporting the existence of lava tubes. In this work, we try to find the average Bouguer gravity profiles across the lava tubes from GRAIL mission, for the physical properties of their subsurface density anomalies.
Traditional inversion methods based on gradient theory usually leads to the best model with minimum-misfit objective function. However, the results are easily influenced by the initial model and a variety of weighting factors. In this study, we adopt the popular Markov Chain Monte Carlo (MCMC) statistical method to detect possible subsurface density deficits. Different weighting factors are set as hyper-parameters and are quantitatively evaluated for density anomaly influence. Uncertainty analysis is carried out to infer the most likely lave tubes.
Comparison of different methods to produce local climate zone maps using the LczExplore tool
Authors: Bocher Erwan , Gousseff Matthieu , Jérémy Bernard , Le Saux Wiederhold Elisabeth , Alglave Baptiste , Kerjouan Emmanuelle
Published: March 2024

Urban climate conditions under global or regional change are a major stake for city planners and policy makers.Members of the different involved communities need a common way to describe urban territory, a way that urban planners and policy makers can easily comprehend and that at the same time can be validated by specialists of the different science relevant fields : climatology, meteorology, building energy, environment and social sciences...Local Climate Zones (LCZ) have proven their usefulness as an easy to use and scientifically founded concept.Several methods aim at classifying a territory into LCZ, and a few workflow even allow an automatic classification. These methods produce maps which are often similar, but may show some differences, due to input data or implemented algorithm.Outside these technical considerations, to assess the impact of urban planning scenarios, one may also want to compare maps before and after the planned urban renovation projects.Therefore, the need for automation of LCZ map comparison asks for an easy to use tool.The `lczexplore` package is a free open-source package that allows to easily import, visualize, group and compare LCZ maps, even if they do not use the same spatial units / resolution. These LCZ maps can come from vector layers or raster layers. Five steps are usually performed by the tool:1. The LCZ classifications (or any other qualitative variables) are imported from a file (geojson or shapefile format)2. Each LCZ classification can then be visualized3. Some LCZ levels may be grouped in broader categories4. A pair of LCZ classifications (or qualitative variable maps) can then be compared:- a map of agreement/disagreement is produced,- the general agreement and a pseudo-kappa indicator of agreement are computed,- the summed surface of each LCZ type is computed for each classification,- a confusion matrix shows how the levels of one LCZ classification break up into the levels of the other5. Influence of the level of confidence on the agreement between classifications is performed (sensitivity analysis)To illustrate the use of LczExplore, we propose a study case where three different maps are compared :- one created within the WUDAPT project, an approach using remote sensor data and machine-learning algorithm- a second created using the GeoClimate software and geographical data provided by an institutionnal actor (the French National Geographical Institute)- a third created using the GeoClimate software and crowdsourced geographical data (from OpenStreetMap).The use of lczexplore package allows to easily visualize how the different map agree or differ, and gives insight on how methods can be complementary to each other, and how input data or algorithms could be improved in the future.
Assessing Antarctic Ice Sheet dynamics under temporary overshoot and long-term temperature stabilization scenarios  
Authors: Spezia Emma , Lacroix Fabrice Kenneth Michel , Visnjevic Vjeran , Wirths Christian , Hermant Antoine , Frölicher Thomas , Sutter Johannes
Published: March 2024

Current projections of Antarctic Ice Sheet dynamics during the next centuries are subject to large uncertainties both reflecting the ice sheet model setup as well as the climate pathways taken into consideration. Assessing both we present model projections of the Antarctic Ice Sheet’s response to a range of temporary temperature overshoot and stabilization scenarios until the year 2500 accounting for various ice sheet sensitivities. We employ the ice sheet model PISM at continental scale forced by Earth system model data tailored to specific global temperature scenarios via an adaptive greenhouse gas emissions approach. These scenarios reflect both emission pathways which result in a transient temperature overshoot during the 21st and 22nd century as well as stabilization of global temperatures without overshoot. We contrast these simulations with the well- known CMIP6 scenarios to illustrate the diverse potential pathways of Antarctic Ice Sheet dynamics under uncertain future climate trajectories. 
Vulnerability assessment of Arctic coastal communities to the effects of coastal erosion and permafrost warming.
Authors: Tanguy Rodrigue , Bartsch Annett , Nitze Ingmar , Irrgang Anna , Petzold Pia , Widhalm Barbara , von Baeckmann Clemens , Boike Julia , Martin Julia , Efimova Aleksandra , Vieira Gonçalo , Heim Birgit , Wieczorek Mareike , Grosse Guido , Ehrich Dorothee
Published: March 2024

This study assesses the escalating vulnerability of Arctic coastal communities due to the combined impacts of coastal erosion and permafrost warming. With the Arctic experiencing heightened temperatures, coastal permafrost areas face increased instability, endangering vital infrastructures. The study focuses on a pan-Arctic evaluation of settlements and infrastructures at risk, enhancing the existing Arctic coastal infrastructure dataset (SACHI) to include road types, airstrips, and artificial water reservoirs.By analyzing coastline change rates from 2000 to 2020, alongside permafrost ground temperature and active layer thickness trends from the ESA Permafrost Climate Change Initiative datasets, the research identifies settlements at risk for the years 2030, 2050, and 2100. The accuracy of the dataset is rigorously evaluated. Results indicate that by 2100, 23% of coastal settlements will face the impacts of coastal erosion. Projections based on linear trends suggest an 8°C increase in coastal permafrost ground temperature and a 0.9-meter growth in active layer thickness by the same year.Crucially, the study reveals that 65% of all infrastructures and settlements will be affected by permafrost warming within the range of 5-15°C, with 35% experiencing active layer thickening between 1-5 meters. This research marks the first regional-scale identification of settlements at risk from coastal erosion along Arctic and permafrost-dominated coasts in the northern hemisphere. The findings emphasize the urgency of adapting to current and future environmental changes to mitigate the deterioration of living conditions in permafrost coastal settlements. Immediate action is imperative to counteract these challenges and ensure the resilience of these vulnerable communities.
Extreme precipitation events in firn core isotopic records: where to find the best drilling site?
Authors: Agosta Cécile , Leroy-Dos Santos Christophe , Fourré Elise , Casado Mathieu , Cauquoin Alexandre , Werner Martin , Landais Amaëlle
Published: March 2024

Extreme precipitation events (EPE), defined as the top 10% of daily precipitation amounts, play a major role in Antarctica surface mass balance as they account for more than 40% of the total annual precipitation across the continent. These EPEs are often associated with high temperatures and have major consequences on the Antarctic surface mass balance. Though, it is key to estimate their recent evolution in terms of frequency and intensity in the context of climate change. As water stable isotopic composition of firn cores is known to record the temperature signal modulated by precipitation intermittency, and to be imprinted as well as by the large-scale atmospheric circulation, we can ask if EPEs could be detected in firn cores thanks to a particular isotopic signature.In this study we construct Virtual Firn Cores (VFC) across Antarctica to investigate how winter EPEs can be misinterpreted as summer maxima in firn cores. We create VFC using (1) temperature, precipitation rate and a linear temperature-d18O relationship from atmospheric regional model MAR, (2) d18O in precipitation from ECHAM6-wiso and (3) d18O in precipitation from LMDZ6-iso, for the period 1979-2022. Additionally to standard VFCs, we generate a second set of VFCs excluding each year the highest winter precipitation event (5-days period). We then run a detection algorithm to find local maxima for both sets of VFCs. We observe some regions with nearly 20% more “summer” detected in standard VFCs compared to VFCs without the winter maximum precipitation event. We argue that firn cores drilled in those regions are more likely to contain isotopic signals that could be used to detect EPEs temporal variability.
Three-Dimensional Hydrodynamic and Microplastic Transport Model for Lentic Systems
Authors: Jagau Lisa , Gilfedder Benjamin , Fleckenstein Jan , Aizinger Vadym
Published: March 2024

Numerical modeling is an efficient tool for quantifying transport and sedimentation patterns of microplastic (MP) particles in lentic systems. To evaluate these patterns based on a specific research area we set up a three-dimensional hydrodynamic and transport model for a reservoir in Germany.We partition the computational domain with an unstructured mesh to optimally capture the geometry of the reservoir and to adapt the mesh resolution. Thereby, shallow areas and those with steep bathymetry gradients are represented at a particularly high resolution. In vertical direction, we use a combination of z- and sigma-layers. To quantify the effects of the grid on the model results, we perform a sensitivity analysis for different horizontal and vertical mesh resolutions.For the hydrodynamic simulations we use the Delft3D Flexible Mesh Suite (Delft3D FM). We calibrate and validate the hydrodynamic model utilizing monthly measured vertical temperature profiles for two different years. For simulating the MP transport, we rely on the sediments and morphology module of Delft3D FM. This module is based on a Eulerian approach which allows us to efficiently simulate large concentrations of MP particles.
Accurate characterization of graphite in ores and black mass using an innovative sample preparation method for automated mineralogy
Authors: Bouzahzah Hassan , Lenoir Laura , pirard Eric , Mermillod-Blondin Raphaël
Published: March 2024

Automated mineralogy systems are widely used for the mineralogical characterization of powder samples for mineral processing purposes. This characterization method requires the mineral powder to be embedded in a resin (polished block (PB) preparation). Very quickly, some problems linked to polished block preparation arose. This particularly involves the mineral settlement in the liquid resin due to differences in mineral size and density. Several authors have suggested solutions to overcome the error results due to the PB preparation method, such as vertical section, the addition of sized graphite, dynamic hardening, and the addition of black carbon (BC) to increase resin viscosity avoiding mineral settlement. Only the BC method resolved all the errors associated with the PB preparation. Indeed, it eliminated the mineral settlement and provided excellent spatial dispersion of particles on the observation surface, ensuring better mineral quantification and liberation/association estimation, except for the graphite-bearing samples. In fact, as graphite shows no contrast with resin under back-scattered electron-based based images, it cannot be characterized by the automated mineralogy systems. few studies have addressed this problem by the addition of carnauba wax or iodoform to contrast resin and graphite. The iodoform was easy to use and provided better contrast compared to carnauba wax. This work presents an innovative polished block preparation method that combines CB and iodoform to prevent both particle settlement and to contrast the resin and graphite which was very challenging. The obtained results are highly satisfying and comparable to those of standard characterization techniques such as XRD and chemical assay. This new preparation method is highly useful for graphite-bearing black mass (obtained from battery recycling) characterization by automated mineralogy systems.
Sampling the diurnal and annual cycles of Earth’s energy imbalance with constellations of satellite-borne radiometers
Authors: Hocking Thomas , Mauritsen Thorsten , Megner Linda
Published: March 2024

The Earth’s energy imbalance (EEI), i.e. the difference between incoming solar radiation and outgoing reflected and emitted radiation, is the one quantity that ultimately controls the evolution of our climate system. Despite its importance, the exact magnitude of the energy imbalance is not well known, and because it is a small net difference of about 1 Wm−2 between two large fluxes (approximately 340 Wm−2), it is difficult to measure directly. There has recently been a renewed interest in applying wide-field-of-view radiometers onboard satellites to measure the outgoing radiation, and hence deduce the global annual mean energy imbalance.Here we investigate how to sample with a limited number of satellite orbits, in order to correctly determine the global annual mean imbalance. Using observational and model data, we have investigated the importance of the local and global diurnal cycles, as they are observed by a satellite, in the determination of the EEI. We simulate satellites in polar (90° inclination), sun-synchronous (98°) and precessing orbits (73°, 82°), as well as constellations of these types of satellite orbits. We present the results of ongoing work concerning different orbits, and how they affect the estimated global annual mean EEI.
Far Ultraviolet atomic emissions at comet 67P: What have we learned? 
Authors: Galand Marina
Published: March 2024

Auroral emissions have been observed throughout the Solar System. They are the photo-manifestation of the interaction of energetic, extra-atmospheric particles (typically electrons or ions) with an atmosphere. As the source of energy comes from the space environment (e.g., solar wind or magnetosphere if applicable), the auroral emissions are a tracer of plasma bombardments in an atmosphere. They are also a fingerprint of plasma source and atmospheric species. They are an invaluable, remote-sensing probe of plasma interaction in the Solar System.Through a multi-instrument analysis of gas, particle and spectroscopic dataset from Rosetta, we have established that the atomic emissions observed in the coma of comet 67P at large heliocentric distances (> 2 astronomical units) are of auroral origin [Galand et al., Nature Astronomy, https://doi.org/10.1038/s41550-020-1171-7, 2020; Stephenson et al.., A&A, https://doi.org/10.1051/0004-6361/202039155, 2021]. We will discuss the source of the energetic particles responsible for the Far UltraViolet (FUV) emissions and will highlight the relevance of observing some of them from Earth. We will contrast these emissions with those observed at comets in the soft X-rays and extreme ultraviolet and with the FUV emissions observed at Earth, Mars and Ganymede.
Microphysical Modeling of Water Isotopic Composition in the Asian Summer Monsoon
Authors: Clouser Benjamin , KleinStern Carly , Singer Clare , Sarkozy Laszlo , Khaykin Sergey , Lykov Alexey , Viciani Silvia , Bianchini Giovanni , D'Amato Francesco , Homeyer Cameron , Legras Bernard , Wienhold Frank , Moyer Elisabeth
Published: March 2024

The summertime Asian Monsoon (AM) is the single most important contributor to water vapor in the UTLS and overworld stratosphere. Much of that water comes from sublimating ice, but the life cycle of the condensate lofted by overshooting convection is not well understood. We report here on insights into that life cycle derived from the first in-situ measurements of water vapor isotopic composition over the Asian Monsoon. The Chicago Water Isotope Spectrometer (ChiWIS) flew on high-altitude aircraft in the monsoon center during the StratoClim (2017) campaign out of Nepal, and in monsoon outflow during ACCLIP (2022) out of South Korea. Both campaigns sampled a broad range of convective and post-convective conditions, letting us trace how convective ice sublimates, reforms, and leaves behind characteristic isotopic signatures. We use isotopic models, along with TRACZILLA backtrajectories and convective interactions derived from cloud-top products, to follow the evolving isotopic composition along flight paths in both campaigns. Results support the wide diversity of isotopic enhancement seen in both campaigns and show how temperature cycles downstream of convective events modify environmental isotopic compositions.
Investigating Early Warning Signals in Climate Simulations using Complex Networks
Authors: Moinat Laure , Kasparian Jérôme , Brunetti Maura
Published: March 2024

Early Warning Signals (EWS) are indicators that can be used to anticipate tipping points i.e. abrupt changes in dynamical systems. Detecting EWS is a crucial part of climate science, especially in the context of climate change. Several methods are used to identify tipping points using time series of climate state variables (e.g. temperature, precipitation, etc), but few consider spatial correlations [1]. Spatial detection could identify the starting location of a transition process from a state to another and be directly applied to satellite observations. We consider different state variables on a numerical grid as a complex network, where grid points displaying correlation are connected and the temporal evolution of this network is studied. We seek for network properties that can be used as EWS when approaching the state transition. The network is generated and analysed using the pyUnicorn package [2], and compared to classical statistical methods. The networks are constructed using two methods: Pearson correlation coefficient and mutual information, allowing us to compare a linear and a causal approach. Multiple network indicators such as the degree of correlation, the average path length, and the area weighted connectivity are compared. To test the method robustness, we look at the network dependencies in terms of the time window, the interval over which the forcing is changed, and the effect of reducing the extent of the network (limited, for example, over polar or equatorial regions). These indicators show tipping points at the global scale, as simulated in a coupled-aquaplanet configuration with the MIT general circulation model, using as forcing parameter the atmospheric CO2 content or the input of solar energy [3] . The application of such indicators as EWS is discussed. [1] van der Mheen et al. Geophysical Research Letters 40, 11  (2013)[2] Donges et al. Chaos 25, 113101 (2015)[3] Brunetti \& Ragon, Physical Review E 107, 054214 (2023)
Enhancing Flood Preparedness: Modeling the Shishper glacier's Glacial Lake Outburst Flooding in Pakistan using Satellite Data and 2D Hydraulic Modeling
Authors: Urban Aleš , Naz Falak , Azadi Hossein , Naeem Babar , Zaidi Arjumand
Published: March 2024

The Shishper Glacier in Pakistan has caused multiple incidents of glacier lake outburst flooding (GLOF), including recent events that occurred in consecutive years. The presence of an ice-dammed lake created by the Shishper Glacier poses significant risks to communities, infrastructure, and people's livelihoods downstream. To decrease the likelihood of GLOFs associated with the Shishper Glacier, it is important to implement an early warning system and effectively manage the water release from the glacial lake. This study used satellite imageries from Landsat and Sentinel 2, and ALOS 30 m DEM, to analyze the areal and volumetric expansion of glacial lake, formed by the blockade of Mochuwar Glacier by terminus of Shishper Glacier at the point of confluence. This terminus extends further downstream and has been the cause of several GLOF events in past. The Shishper Glacier has recently had many surges, the most recent of which occurred in 2022, 2020, 2019 and 2018. In this study, HEC-RAS 2D model was used to reproduce the Shishper glacier lake outburst flooding (GLOF2022) and assess its impacts on the areas located downstream. The findings of the study will contribute to proactive measures that can prevent future disasters and ensure the safety of the vulnerable population and critical infrastructure. 
Lassoing Fish — Linking tropical Fish cloud structures to extratropical fronts
Authors: Mieslinger Theresa , Windmiller Julia , Stevens Bjorn
Published: March 2024

People on Barbados are used to “rope-like” cloud structures passing over the island and their association with more disturbed weather conditions. In more recent literature, such cloud structures are frequently named Fish owing to their fishbone-like appearance on satellite images. Schulz et al., 2021, identified Fish cloud structures in satellite imagery via machine learning and showed that they have a pathway coming from the extratropics and often show a frontal character based on their surface convergence field, both indicative of them being associated with extratropical fronts. Extratropical fronts are known to impact convection in the tropics. A wealth of past studies based on theory, observations and modelling showed the distinct water-vapor structure, precipitation characteristics, as well as radiative-dynamical mechanisms of extratropical intrusions and highlight their importance for tropical moist convection.In our study, we investigate the link between well-studied extratropical fronts and Fish-like cloud appearances. We apply a neural network to identify Fish cloud structures across the global tropics and investigate them with respect to the characteristics of well-studied extratropical fronts. We aim to answer the questions whether all Fish patterns are the visual imprint of extratropical fronts and how their thermodynamical and dynamical properties change as they propagate to lower latitudes.
Differential absorption G-band radar for Arctic clouds and water vapor observations
Authors: Schnitt Sabrina , Mech Mario , Goliasch Jens , Ori Davide , Rose Thomas , Crewell Susanne
Published: March 2024

The Arctic climate is changing at fast pace. The contribution of low-level clouds to Arctic amplification feedback processes remains challenging to quantify as model evaluation requires continuous, high-quality observations in a demanding environment. Advancing the understanding of governing processes in mixed-phase clouds, ubiquitous in the Arctic, calls for temporally high-resolved measurements of cloud and precipitation microphysical properties as well simultaneous quantification of water vapor amount and profiles in all-weather conditions. We present the novel and worldwide unique G-band Radar for Water vapor profiling and Arctic Clouds (GRaWAC) system, suitable to deliver these measurements. GRaWAC is a FMCW G-band radar with Doppler-resolving capabilities and simultaneous dual-frequency operation at 167 and 175GHz. The Differential Absorption Radar technique is applied to the measurements to derive temporally continuous water vapor profiles in cloudy and precipitating conditions, which closes a current gap in observational state-of-the-art instrumentation. We reveal first measurements from a mid-latitudinal ground site and airborne test flights to illustrate GraWAC’s potential for water vapor, cloud and precipitation profiling. Based on instrument simulations, we outline the benefits of such observations at an Arctic ground-based supersite, such as AWIPEV station, Ny-Alesund, Spitsbergen. There, the G-band radar measurements will be embedded in a synergy of remote sensing instruments, including an operational microwave radiometer and a Ka- and W-band cloud radar, respectively. We highlight future applications of these synergistic measurements, and therein especially the multi-frequency radar space, for model evaluation studies targeting an improved representation of mixed-phase clouds in the Arctic.
Apportionment of absorption in complex aerosols in South Africa
Authors: Baldo Clarissa , Language Brigitte , Isolabella Tommaso , Vernocchi Virginia , Massabò Dario , Di Biagio Claudia , Van Zyl Pieter , Piketh Stuart , Formenti Paola
Published: March 2024

South Africa, with its industrialised economy, faces unique air pollution challenges. Our study investigates aerosol composition and absorption in the Highveld region. Understanding aerosol absorption is critical as it affects climate, air quality, and public health. Aerosol absorption in the lower atmosphere affects the evolution of the boundary layer and the dispersion of pollutants, which in turn affects air quality and public health. Aerosol filter samples (PM10 fractions) were collected from residential, traffic, and industrial sites during the dry season. Chemical analyses, including X-ray fluorescence, thermo-optical analysis, and ion chromatography, were carried out to determine elemental species, carbonaceous species, and water-soluble ions, respectively. Based on this, a mass closure calculation was performed to define the contribution of five major aerosol components. The calculated aerosol mass concentrations were in good agreement with the measurements (Normalised Mean Bias, NMB < 7%). No significant variation in PM10 concentration was observed between site types. Mineral dust appeared to be the main contributor to PM10, varying from about 48%-60% at different sites, followed by organic matter (OM, 22%-35%), secondary inorganic aerosols (SIA, 9%-12%), elemental carbon (EC, 4%-7%), and sea salt (ss, 1%-2%).Aerosol spectral absorption was obtained from multi-wavelength absorbance analysis (MWAA) measurements at 375, 407, 532, 635, and 850 nm. High absorption was measured in the following order: industrial> residential> traffic sites. The estimated absorption Ångström exponent (AAE) varied from 0.8 to 2 at different sites, indicating the contribution of several sources. At 850 nm absorption correlates well with EC as expected (r = 0.85). The obtained mass absorption efficiency (8 m2/g) is in line with expectations. Specific tracers were used to determine the contribution of the main absorbing aerosol components - black carbon (BC), brown organic carbon (BrC) from incomplete biomass combustion, and mineral dust - using correlations between estimated mass and measured absorption. Preliminary results indicate that although BC is the major contributor to absorption, accounting for 30%-60% absorption at 375 nm, followed by BrC 10%-50%, the contribution of the less absorbing but more abundant mineral dust is not negligible and can range from 2% to 50% in different samples. These results underline the complexity of aerosols in the region and their high absorption properties, and the need for a comprehensive understanding of its various components to accurately assess its impact.
Understanding snow meltwater fractional contributions to streamflow in a subarctic catchment
Authors: Ala-aho Pertti , Noor Kashif , Welker Jeffrey M. , Mustonen Kaisa-Riikka , Klöve Björn , Marttila Hannu
Published: March 2024

Snow plays an important role in the Northern water cycle providing temporary water storage, and resulting in high flows during spring snowmelt. Snow is experiencing rapid changes due to global warming, and process-based understanding of how snowmelt interacts with the environment is becoming ever more important. Stable isotopes of 18O and 2H are recognized as reliable tracers for determining water sources and tracing their movement within a catchment. The Isotope-Based Hydrograph Separation (IHS) is used to determine the mix of water sources in streams. However, when determining the snowmelts contribution to streamflow using IHS, uncertainties arise due to the lack of a clear and consistent snow sampling approach do define the isotope signal of snowmelt water for IHS calculations. To tackle these uncertainties, we did intensive sampling of snowfall, snowpack, and snow meltwater 18O isotopes at the Pallas catchment in Northern Finland. Our examination of different snow sampling strategies revealed potential biases in the IHS analysis. By employing samples directly from the snowmelt water 18O isotope value as an endmember in IHS, we determined the fractional contribution from streamflow was 59.6% (with a ±2% uncertainty). Yet, using alternate average weighted isotope values from either snowfall or mid-winter snowpack resulted in underestimations of snowmelt fraction by 17.8% and 22.6% respectively. In the absence of snowmelt samples, samples collected from the snowpack during high snowmelt period resulted in smaller biases (4.2 % lower snowmelt fractions). Our findings underline the importance of selecting the right snow sampling method for IHS, or any other ecohydrological analysis using stable water isotope tracers.
 A two-dimensional model for the dynamics of sand patches
Authors: Rambert Camille , Narteau Clément , Nield Joanna , Wiggs Giles , Delorme Pauline , Baddock Matthew , Claudin Philippe
Published: March 2024

Sand patches are one of the early stages of aeolian bedforms. They form onnon-erodible surfaces in both desert and coastal environments. Their initiation is associated with thechange of saltation transport law on rigid and granular beds [1]. Here wepresent a two-dimensional model that couples these surface-dependenttransport laws with the feedback of the bed elevation on the wind flow.Analysing the spatio-temporal evolution of an initial very flat sandpatch, we emphasise the central role of the input flux as well as thelengthscale over which occurs the transition between the two transportlaws. We also show that, for adjusted parameters of the model, we are ableto reproduce the growth and the propagation of these small metre-scalebedforms over time, in quantitative comparison with field measurements.[1] P. Delorme, J.M. Nield, G.F.S. Wiggs, M.C. Baddock, N.R. Bristow, J.Best, K.T. Christensen and P. Claudin, Field evidence for the initiationof isolated aeolian sand patches, Geophys. Res. Lett. 50 , e2022GL101553(2023).
Convection-Permitting Climate Models: Present and Future Insights on daily and sub-daily Extreme Precipitation in Norway
Authors: Xie Kun , Li Lu , Sobolowski Stefan , Chen Hua , Xu Chong-Yu
Published: March 2024

Convection-permitting climate models (CPMs) have demonstrated enhanced capability in capturing extreme precipitation compared to convection-parameterization models. Despite this, a comprehensive understanding of their added values in daily or sub-daily extremes, especially at local scale, remains limited. In this study, we conduct a thorough comparison of daily and sub-daily extreme precipitation from HCLIM3 and HCLIM12 across Norway, divided into eight regions, using gridded and in-suit observations. Our main focus is to investigate the added values of HCLIM3 compared to HCLIM12 for precipitation extreme indices at daily and sub-daily time-steps on both local and regional scales. We find that the HCLIM3 better captures the maximum 1-day precipitation (Rx1d) at most of the regions except south-western region. Notably, the performance of HCLIM3 in capturing Rx1d shows a notable coastal-inland division, overestimating along the coastal areas and underestimating in the inland regions. In general, HCLIM3 better matches observations than HCLIM12 for daily and sub-daily precipitation extreme indices at regional scale in Norway. However, at the local scale, neither HCLIM3 nor HCLIM12 can capture the temporal evolution of Rx1h during 10 years, except one station near Oslo (eastern region), where only HCLIM3 fits the observations. In general, HCLIM3 performs better than HCLIM12 on Rx1d and Rx1h in Norway with the mean of bias distribution closer to zero, although it varies a bit among regions (for example, HCLIM3 performs worse in the south-western region). In addition, the seasonality of Rx1h can be also better captured by HCLIM3 at both regional and local scales, while HCLIM12 tends to underestimate hourly extremes. In a future warming climate, HCLIM3 with higher Clausius-Clapeyron (CC) scaling, exhibits a higher increase than HCLIM12 in the Rx1h and Rx1d over most regions of Norway except southern and south-west regions. Under global warming, short-duration extreme events with greater CC scaling have a higher increase rate than long-lasting events. This study highlights the importance of more realistic convection-permitting regional climate predictions and projections in providing reliable insights into the characteristics of precipitation extremes and their future changes across Norway's eight regions. Such information is crucial for effective adaptation management to mitigate severe hydro-meteorological hazards, especially for the local extremes.
Could tree species be a key factor on soil carbon balance in temperate forest?
Authors: Bonnefoy-Claudet Clément , Thevenot Mathieu , Lévêque Jean , Cognard Elodie , Santoni Anne-Lise , Cacot Jean , Mathieu Olivier
Published: March 2024

Soils play a key role in regulating atmospheric concentrations of greenhouse gases notably by their action on organic carbon dynamics (storage vs. release). Forests occupy 31% of the continental surface and store around 40% of the continental organic carbon, half of it in soils. Ongoing climate change could alter the balance of this stock, and the effect of temperature on soil carbon fluxes remains an important question. In this study, we use the Q10 parameter (i.e. increase in CO2 emission for a 10°C rise in temperature) to estimate the temperature sensitivity of soil organic matter in four forest tree species (beech, spruce, douglas fir and silver fir). In addition, soil organic carbon stocks were estimated and compared with Q10 values and forestry data (volume, basal area, density and dead wood).The mont Beuvray site (Morvan Regional Park, France), a mid-mountain area of around 1,000 ha with a quite homogeneous geology and pedology, was selected. On this site, Beech forests correspond to historical land use, while softwood forests have been gradually introduced over the past 70 years. Thus, 48 soil samples (0-20 cm) were collected (12 per tree species) and the main physicochemical characteristics were determined (bulk density, stone content, pH, organic carbon and total nitrogen contents, water-extractable organic carbon). The Q10 was calculated for a temperature range of 5 to 25°C in the laboratory using a Respicond X (Nordgren Innovations AB, Sweden).Results show that soil organic carbon and water-extractable organic carbon contents are higher in silver fir and beech stand soils than in Douglas fir stand soils. For soil organic carbon stocks, the average values are slightly higher for beech and silver fir than for Douglas fir and spruce, but there is no statistical difference between the four tree species.  Q10 values range from 2.3 to 3.0, with a statistical higher value for beech (2.8 ± 0.1) than for the other softwood species (2.6 ± 0.1). This last result suggests that, for similar initial soil conditions, CO2 emissions from soil in beech stands would increase more strongly with temperature than in other species.In conclusion, several decades after the introduction of softwood species, we did not measure in the top soil (0-20 cm) significant difference in carbon stocks. However, CO2 emissions and Q10 values are different and related to forest species. Hence, beech stand soils, corresponding to the historical land cover, could see their CO2 flux increase as they are the most sensitive to temperature. Conversely, silver fir stands, with their lower sensitivity to temperature, could be of interest in mitigating emissions. These results need to be confirmed by field data on soil respiration and compared with above-ground forest biomass and stand health.