bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantile regression forests for post-processing ECWMF ensemble precipitation forecasts: hyperparameter optimization and comparison to EMOS
Authors: van der Kooij Eva , Squintu Antonello , Whan Kirien , Schmeits Maurice
Published: February 2023

Ensemble forecasts are important due to their ability to characterize forecast uncertainty, which is fundamental when forecasting extreme weather. Ensemble forecasts are however often biased and underdispersed and thus need to be post-processed.A common approach for this is the use of ensemble model output statistics (EMOS), where a parametric distribution is fitted with a limited number of predictors. With recent advances in computer science and increased amounts of data available, machine learning techniques, like random forests, are becoming more popular for high dimensional regression problems. In this research, we explore the use of the quantile regression forest (QRF), a random forest adapted for conditional quantile estimation, applied to medium range gridded probabilistic precipitation forecasts. QRFs are non-parametric and allow for a larger number of predictors, which means they can possibly consider more dependencies that might otherwise not be captured with a simple EMOS.A QRF takes several hyperparameters that influence the way the decision trees in the forest are constructed. We explore the minimum number of samples needed in a leaf to split it (minimum node size) and the number of predictors explored in each split (mtry). A hyperparameter space is constructed by setting ranges for both minimum node size and mtry, and the optimal hyperparameter set is determined by performing a cross validated grid search. Here, each model is assessed based on the continuous ranked probability skill score (CRPSS). For comparison, EMOS is applied with a zero-adjusted gamma (ZAGA) distribution, using a limited number of predictors that are physically correlated to precipitation. Both methods are verified on a separate testing data set and evaluated using several scores, including CRPSS and Brier skills score (BSS).We consider 4 years (November 2018 – October 2022) of archived operational ECMWF-IFS ensemble forecasts for the Netherlands. The data is split into November 2018 – October 2021 for training and cross-validation, and October 2021 – October 2022 for testing, separating data for season, initialization time and lead-time. Forecasts are post-processed up to +10 days. Ensemble statistics on 60+ forecast variables are used as predictors. Spatially and temporally aggregated, gauge-adjusted radar observations are used as predictand. The raw ensemble is considered as the benchmark.The results of this research will determine what method will be used to post-process the ensemble precipitation forecasts in the context of the early warning center (EWC) of the Royal Netherlands Meteorological Institute. The most suitable method could differ between shorter and longer lead times.
Hydrogeological, physicochemical, and thermal conditions as drivers of faunal diversity in an urban groundwater ecosystem
Authors: Becher Julia , Gardt Konstantin , Meyer Laura , Griebler Christian , Hermann Martina , Bayer Peter
Published: February 2023

Shallow urban groundwater is habitat of microorganisms as well as invertebrate fauna. Both communities are assumed to be strongly influenced by multiple stressors, such as increased groundwater temperatures and enhanced local hydraulic fluctuations, acting in the urban subsurface. To date, ecological studies mainly focused on natural and arable environments, with little attention to biodiversity and the role of anthropogenic factors in urban groundwater habitats. Our project targets the subterranean regime of the city of Halle (Saale) as an ideal benchmark to explore spatial and temporal dynamics of subsurface biodiversity on the urban scale. The unique hydrogeological setting of Halle, which covers a broad range of different aquifer types, with characteristic subsurface urban warming, allows for the evaluation of selected abiotic factors related to hydraulics, hydrochemistry and temperature trends. We expect new insight into the individual and concerted role of these factors on groundwater microorganisms and fauna.First data were collected within a field campaign in June/July 2022. Physico-chemical parameters in groundwater were recorded with a multiparameter probe at each sampling point. Hydrochemical analysis including major anions and dissolved organic carbon (DOC) was conducted with the water samples from the wells and freshly pumped groundwater. Groundwater animals were collected from the bottom of the wells with a net sampler. Animals were sorted and counted at the level of higher taxonomic groups (e.g. amphipods, copepods, isopods, ostracods, oligochaetes, nematodes, and mites). In the presentation, first results on the hydrogeology, hydrochemistry, microbiology and faunal diversity of the urban center and surroundings of Halle are introduced. We show major spatial trends and how faunal abundance and diversity relates to direct urban temperature effects and zones of anoxic conditions. Moreover, research activities planned for the near future will be discussed.
The 2021 Cumbre Vieja eruption (La Palma, Canary Islands): new perspectives on the geochemistry of lavas and noble gases isotopes trapped in fluid inclusions
Authors: Sandoval-Velasquez Andres , Rizzo Andrea Luca , Casetta Federico , Ntaflos Theodoros , Aiuppa Alessandro , Alonso Mar , Padron Eleazar , Pankhurst Matt , Mundl-Petermeier Andrea , Perez Nemesio M
Published: February 2023

We collected samples from the lava flows from the Cumbre Vieja 2021 eruption, the 1677 San Antonio eruption and picrites from the 3 Ma old Taburiente calderaand in La Palma (Canary Islands) with the aim to investigate the geochemistry of the lavas and their He and CO2 isotopic composition in fluid inclusions. The above information is crucial to better understand the evolution in time of the volcanic system and the nature of the local mantle source.Our results suggest that during the Cumbre Vieja eruption there was a systematic increase in the volatile concentrations (particularly He and CO2) between late September and early October. The above is accompanied by an increase of the whole rock Mg#, CaO/Al2O3 and the Nb/La ratios from 50.5 to 58.7, from 0.78 to 0.87, and from 0.88 to 1.01, respectively (we also observed that these variations coincide with the occurrence of deeper earthquakes; 30-40 km; D’Auria et al., 2022), which likely indicate the intrusion of a more primitive less-degassed magma rising from the asthenosphere at the end of September. Regarding the mineral chemistry, the composition of olivine and pyroxene do not show any noticeable heterogeneity in all analyzed samples. The 3He/4He ratios are homogeneous over time and exhibit MORB-like signatures between 7 and 7.5 Ra. In comparison the whole rock composition and the 3He/4He ratios of the San Antonio lavas are very similar to the lavas erupted in late October-early November 2021, whereas the picritic lavas from the Taburiente caldera show higher 3He/4He ratios equal to 9.4±0.1 Ra that are comparable with the signatures measured in the Dos Aguas cold spring (Pérez et al., 1994; Padrón et al., 2022) indicating plume origin.In conclusion, the He isotopic differences between lavas form northern and southern La Palma could be advocated to the small-scale heterogeneities in the mantle, and/or a plumbing system responsible for the lower 3He/4He of the 2021 Cubre Vieja magmas.  Moreover, considering the more radiogenic helium ratios reported in mantle xenoliths from La Palma (6.5 - 7.2Ra; Sandoval Velasquez et al., 2022) we propose that the isotopic signatures observed at Cumbre Vieja and San Antonio are likely the result of a mixing between a plume component (highlighted by the 3He/4He in the picrites and the Dos Aguas Spring of the Taburiente caldera) and a more radiogenic reservoir located in the shallower lithospheric mantle.
Development of bio-based, biodegradable geotextiles for the revegetation of stabilized landslide-prone areas
Authors: Hofmann-Lanter Helene , Prambauer Martina , Czerski Dorota
Published: February 2023

High-tensile steel nets have established themselves as a solution for stabilising landslide-prone areas. To return an engineered slope as much as possible back to a natural look, thoughts of revegetation should always accompany such stabilisation projects. Different factors play a role in natural revegetation, such as the inclination and orientation of said slope and the erosion potential through water percolation. Sometimes it is necessary to help revegetation when a combination of unfavourable factors is present. This can be achieved by adding a geotextile.When vegetation might take several years to grow, a long-term geotextile is required, which does not degrade in the first years. In such a long-term geotextile, 3D mats out of polypropylene were quite successful. Unfortunately, when it comes to its degradation, sometimes after decades, microplastics are released into the environment. This added an essential aspect to the constantly growing need for substituting petrol-based polymers with nature-based materials. This work highlights the different trials with materials to obtain a controlled degradation of the geotextile material into non-hazardous components. By applying biobased, biodegradable polymers for such applications, the need for material recollection is eliminated, and plastic waste’s impact on the environment is significantly reduced. In this work, biopolymer blend fibres were produced and evaluated in terms of mechanical properties and biodegradability. The blends were based on bio-polyester blends, and the properties were tailored by adjusting the composition of the blend fibres to resemble the existing polypropylene product. The degradation rate of the blend fibres was observed by artificial weathering and hydrolytic degradation tests. As a result, a relation between material structure, fibre strength and durability period was obtained and a complete 3D mat could be produced. Once the material was thoroughly tested in the laboratory, a first small-scale field test was set up in 2020, followed last summer with a large-scale 1:1 field test in southern Switzerland, where careful monitoring assesses the stability of the material as well as the stability of the soil beneath it. The development of the material in the laboratory as well as the first results from the large-scale field test will be presented.
Dust orientation measurements
Authors: Tsekeri Alexandra , Amiridis Vasillis , Metallinos Spyros , Paschou Peristera , Siomos Nikos , Tsikoudi Ioanna , Kouklaki Dimitra , Marinou Eleni
Published: February 2023

Abstract. Dust orientation is an ongoing investigation in recent years (Ulanowski et al., 2007). Its potential proof will be a paradigm shift for dust remote sensing, invalidating the currently used simplifications of randomly-oriented particles. Vertically-resolved measurements of dust orientation can be acquired with the new polarization lidar “WALL-E”, designed to target the off-diagonal elements of the backscatter matrix which are non-zero only when the particles are oriented (Tsekeri et al., 2021). Herein, we present first measurements of oriented dust particles acquired during the ESA Aeolus Cal/Val Campaign “ASKOS” at Cabo Verde (June and September 2022). Acknowledgments: This research was supported by D-TECT (Grant Agreement 725698) funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program and PANGEA4CalVal (Grant Agreement 101079201) funded by European Union’s Horizon Widera 2021 Access program.  References:Tsekeri, A., et al.: Polarization lidar for detecting dust orientation: system design and calibration, Atmos. Meas. Tech., 14, 7453–7474, 2021.Ulanowski, Z., et al.: Alignment of atmospheric mineral dust due to electric field, Atmos. Chem. Phys., 7, 6161–6173, 2007.
Compound effects of extreme spring temperature fluctuations on vegetation phenology
Authors: Liu Guohua , Migliavacca Mirco , Reimers Christian , Bastos Ana , Linscheid Nora , Reichstein Markus , Winkler Alexander J.
Published: February 2023

Strong spring temperature anomalies can have major impacts on the phenological development of vegetation throughout the season. In particular, an unusually warm spring can lead to premature plant development, while late-spring frost events can damage plants and result in reduced growth. However, the effects of early-spring warming and late-spring frost events on the seasonal development of vegetation, as well as their compound effect, still need to be investigated. Here, we apply a data-driven phenological model that accounts for meteorological memory to assess the effects of early-spring warming and late-spring frost events on key metrics of the phenological cycle, including the timing of spring green-up, peak greenness and autumn green-down for various vegetation types using ground-based observations of vegetation greenness (PhenoCam network). We find that early-spring warming leads to an advancement of all key metrics, i.e.,spring green-up, peak greenness and autumn green-down. Late-spring frost events, on the other hand, delay the entire seasonal cycle of vegetation development. The compound effect of both reveals that early-spring warming can compensate for the adverse impacts of late-spring frost events. Our study suggests that large fluctuations in spring temperature and compound events, which could increase in intensity and frequency in a warming climate, need to be considered when predicting the vegetation phenology under climate change.
Increase in Lightning and Upper Tropospheric Water Vapour Over the Arctic Circle
Authors: Guha Anirban , Saha Joydeb , Price Colin
Published: February 2023

Sea ice in the Arctic grows during each hemisphere’s winter and it retreats in the summer. The highly reflective white surface of sea ice reflects solar energy, cooling the planet. When it melts, the darker ocean absorbs more heat, reinforcing the cycle of melting sea ice. Sea ice plays a critical role in regulating Earth’s climate, and it influences global weather patterns and ocean circulations. One essential feedback in the Arctic is the rise in upper tropospheric water vapor (UTWV) or the specific humidity (SH) that acts as an intense greenhouse gas trapping in additional heat released from the Earth's surface.   While temperature change is driven by increasing greenhouse gases, the interannual variability in sea ice can be explained by changes in the UTWV (ASO) at 400mb in the Arctic. Where is this increase in UTWV (400mb) coming from in the Arctic?  Thunderstorm activity appears to be increasing in the Arctic in the last decades, and could be a source of the increasing UTWV, and hence the decrease in Arctic sea ice.
Comparing tree ring chronology and soil water model for a hydric hemiboreal forest
Authors: Kalvans Andis , Dauškane Iluta
Published: February 2023

Air temperature and hence potential evapotranspiration trends are clearly positive worldwide, while precipitation trends are unclear largely due to large inherent variability. Apparently, because of climate change increasing evapotranspiration is likely to lead to depletion of soil water reserves in many ecosystems, but ecosystem feedbacks can have a nonlinear impact of the water regime. For example, in a hemi boreal forest at a hydric setting, higher evapotranspiration due to higher temperatures can lead to improved soil aeration, facilitating the rejuvenation of woody vegetation and further increase of transpiration. Process-based soil water models can be used to investigate such phenomena. However, the models need to be validated. Long time series of the forest soil water regime are sparce. Instead, the tree-ring width data (chronology) can be used as a proxy for growing conditions in the past, as the soil water regime has the firs order controlling factor. We are constructing a Hydrus-1D soil-water model for three hydric forest sample plots in Latvia using the e-obs data set for model forcing. The model results then are compared to the local tree-ring chronology, particularly examining pointer years as extreme cases for evaluating hydrological situation. The model will provide opportunity for scenario investigation of the interactions between climate and soil water regime in hemiboreal forest ecosystem. This work was supported by ERDF postdoctoral research project “Groundwater and soil water regime under climate change” (No. 1.1.1.2/VIAA/3/19/524).
Correlation Analysis of GNSS Data Quality Indicators and Position Time Series using Machine-Learning Algorithms
Authors: Bamahry Fikri , Legrand Juliette , Bruyninx Carine , Pottiaux Eric , Fabian Andras
Published: February 2023

The EUREF Permanent GNSS Network Central Bureau (EPN CB, www.epncb.eu [1]) monitors the quality of the daily GNSS observations of the EPN stations covering the period 1996-today. The associated data quality indicators (the number of observed versus expected observations in dual frequency, the lowest elevation cut-off observed, the number of missing epochs, the number of satellites, the number of maximum observations, and the number of cycle slips) are used to assess EPN stations' performance and as input for outlier detection in the daily position time series of the 400+ GNSS reference stations in Europe. Due to the increasing number of GNSS stations, the development of an automated algorithm to identify coordinate outliers caused by degraded GNSS data quality would allow to reduce the effort of human interpretation of the data quality indicators. We investigate the correlations between daily GNSS data quality metrics and daily position estimates to achieve this.This study assesses several machine-learning classification algorithms to find a suitable data-driven model based on the correlation between degraded GNSS data quality metrics and quality degradation in position time series. Based on this investigation, the Random Forest algorithm proved to be the most precise algorithm, with an Area Under the Receiver Operating Characteristic Curve (AUC) equal to 0.95, and a correct classification of almost 90% of the test dataset. The GNSS data quality indicators ‘maximum observations‘ and ‘cycle slips’ are also shown as the most important parameters driving this model, which is in accordance with the data quality criteria for GNSS stations that IGS has determined [2]. Our model will be implemented in our EPN CB operation routine to develop a new monitoring system that can detect quality degradation on the GNSS station that will enable to improve the reliability of the EPN reference frame product by detecting position outliers due to degraded GNSS data quality. Here, we will present the current development of this automated algorithm, the challenges we faced, and the preliminary results of this work.References:[1] C. Bruyninx, J. Legrand , D. Mesmaker, A. Moyaert, A. Fabian (2022): EUREF Permanent Network Central Bureau (EPN CB) Information System, https://doi.org/10.24414/ROB-EUREF-EPNCB[2] IGS (2019) Questions about the data quality graphs. https://kb.igs.org/hc/en-us/articles/204229743-Questions-about-the-data-quality-graphs
Effect of phlogopite on the strength of mica-quartz assemblage and underlying chemical processes
Authors: Alaoui Lalla Khadija , Airaghi Laura , Stünitz Holger , Raimbourg Hugues , Précigout Jacques
Published: February 2023

While mineral plasticity is often seen as the most important process to deform rocks in the deep, viscous realm, but an increasing number of studies is highlighting the contribution of mineral reactions and chemical processes to bulk strain. This issue is especially acute at the brittle-viscous transition, where plasticity is hampered by the low temperature conditions. In this work, we studied the deformation processes operating in mica+quartz assemblages, representative of greenschist to amphibolite-facies mylonites, with a special focus on the respective contributions of plasticity and dissolution-precipitation processes.Assemblages made of phlogopite (Phl) and quartz (Qz) were experimentally deformed in simple shear (Griggs-type apparatus) at 800°C, 10kbar, shear strain rate ~10-5 s-1 and 0.1 wt. % added H2O.  For well-constrained grain sizes (63μm < Phl < 125μm, 10μm < Qz < 20μm), we varied the phase proportions of phlogopite (10, 20, 30, 50, 70 and 100% vol. Phl).Mechanical results indicate at first order a decrease in strength as the proportion of mica is increased. Samples for 10% vol. Phl deform at differential stresses of ∼1200 and at 20% Phl at ~900MPa, while 100% vol. Phl sample deform for differential stresses as low as ~300MPa. However, the weakest behavior is observed for 30% vol. of mica. The strength of the latter sample lies well out of the iso-strain/iso-stress curves, pointing to the fact that the assemblage does not behave as a simple mechanical mixture of the two end-member mineral phases.In all samples, an important grain size reduction is noticeable for mica flakes. Grain size reduction is also present for quartz grains, especially with decreasing proportion of mica in the assembly. Most of the strain is accommodated by quartz as an interconnected network in Phl-poor samples, while in Phl-rich samples, phlogopite grains are interconnected. In quartz, a weak intragrain deformation is observed for most samples with no evidence for dynamic recrystallization Quartz is largely reworked as attested by trace element variations, with the reworked quartz proportion decreasing with increasing abundance of phlogopite Only the 10% vol. Phl sample is characterized by incipient polygonal subgrains between parent quartz grains (Qz1). Quartz is reworked mainly by dissolution-precipitation, with newly formed product (Qz2) surrounding original, inherited quartz grains. Qz2 is characterized by a large microporosity, and is enriched in aluminum compared to Qz1. The contribution of dissolution-precipitation seems to be maximal in the weakest sample (30% vol. Phl). Therefore, our study shows that dissolution precipitation processes are instrumental to weaken the two-phase material and that bulk strength strongly deviates from composite flow laws in case of a purely mechanical mixing.
Seasonal forecasts for Germany: Enhancing the predictive capability of global SEAS5 ensemble forecasts using bias correction
Authors: Weber Jan Niklas , Lorenz Christof , Portele Tanja , Kunstmann Harald
Published: February 2023

For an optimized use of water resources for irrigation or power generation, knowledge of their expected availability in the coming months is essential. This particular sub-seasonal to seasonal time horizon is covered by seasonal forecasting systems like SEAS5 from the European Centre for Medium-Range Weather Forecasts (ECMWF), which could provide crucial information for an improved and more timely water management. In this study, we evaluate the skill of precipitation and temperature forecasts from SEAS5 for Germany. The performance of forecasts without any post-processing or bias-correction remains below the climatology from the second lead month. To increase the performance, we apply a post-processing approach for Bias Correction and Spatial Disaggregation (BCSD) to a) increase the spatial resolution and b) reduce biases compared to our chosen reference ERA5-Land. By means of several quality parameters such as the Continuous Ranked Probability Skill Score (CRPSS) and the Brier Skill Score (BSS), it is shown that the corrected SEAS5 seasonal forecasts at monthly resolution deliver a significantly increased performance compared to purely climatological forecasts and raw SEAS5 forecasts, especially in the first forecast month. Special focus is put on climatic extremes, since especially here the seasonal forecasts have the potential to provide highly valuable information that are, by definition, absent, e.g., in climatological forecasts. This is clearly evident for compound events, which show increased predictability up to five months in advance. Months with normal conditions perform rather poorly, whereas abnormally warm or dry months are well forecasted up to and including the sixth lead month. Temperature variables perform particularly well, while precipitation forecasts show lower skill. Forecasts of the Standardized Precipitation Evapotranspiration Index (SPEI, a widely used indicator for droughts and, hence, limited water availability) show higher skill than pure precipitation forecasts. We further assess the performance of post-processed SEAS5 forecasts in terms of the Potential Economic Value (PEV), which allows for the quantification of economic savings due to forecast-based actions. Depending on a well-chosen cost-loss-ratio of particular actions, seasonal forecasts from SEAS5 show a promising skill for timely decision making in the water management and related sectors. In our presentation, we hence demonstrate the skill of post-processed seasonal forecasts from SEAS5 over Germany and provide a benchmark for other forecasting products and post-processing routines.
Priming effects decrease with quantity of cover crop residues – implications for net soil carbon sequestration
Authors: Liang Zhi , Rasmussen Jim , Poeplau Christopher , Elsgaard Lars
Published: February 2023

Recent meta-analyses suggest a global potential of cover crops to increase soil organic carbon (SOC), thus contributing to climate change mitigation. However, some studies also found that cover cropping did not affect or even reduced SOC, thus it is uncertain how this effect is controlled. Here we aimed at comprehensively evaluating the potential and mechanisms of carbon (C) sequestration from cover crops in a Danish long-term crop rotation field experiment (LTE) initiated in 1997. We quantified SOC to 1-m depth, and also operationally divided soil organic matter into fractions of particulate organic matter (POM) and mineral associated organic matter (MAOM) to investigate the C saturation status of soils. Moreover, we performed a mescosm study with topsoils where the fate of varying doses (0.1-1.6 mg C g-1 soil) of 14C-labeled cover crop residues (fodder radish, FR; Raphanus sativus L.) and SOC priming were traced in two texturally similar soils having the same long-term management, but different SOC contents (2.0 vs. 2.6% SOC). Our LTE results showed that cover cropping for up two decades had negligible effect on SOC contents in POM and MAOM fractions in the topsoil and in the subsoil. However, the mesocosm study showed considerable net C increases (20-25% of added) when the cover crop C input exceeded 0.3 and 0.6 mg C g-1 in soils with 2.0 and 2.6% SOC, respectively. This was due a combination of new SOC formation and priming effects shifting from positive to negative. Collectively the LTE and mesocosm study suggests that buildup of SOC stock was not essentially constrained by soil C saturation, but rather by the low productivity and C input from cover crops. Our study suggests that agricultural management practices should be adopted (e.g., species choice and sowing time) to achieve a cover crop C input that exceeds a certain threshold to ensure effective C sequestration.
Estimating the efficiency of open ocean alkalinization
Authors: Steinfeldt Reiner , Rhein Monika
Published: February 2023

The efficiency of open ocean alkalinization is estimated for four regions in the Atlantic: the subpolar North Atlantic, the northern subtropics, the equatorial region and the Southern Ocean. Therefore, a simple one-dimensional model is applied. First, observational based surface values of temperature, salinity, alkalinity, mixed layer depth (MLD), air-sea gas exchange velocity and pCO2 for each region are derived from the ARMOR3D data set (Guinehut et al., 2012) and the surface pCO2 data product by Landschützer et al. (2020). The model is run for 26 years, using the data from 1994 to 2019. Alkalinity is added to the mixed layer, which leads to enhanced oceanic carbon uptake, depending on the change in pCO2 and the gas transfer velocity. When the mixed layer shallows, parts of the added substances remain in the deeper layer of the model (below the mixed layer). They can either be exported, or can be entrained into the mixed layer again when it deepens. In this way, the efficiency of alkalinization (mole of absorbed CO2 per mole of added alkalinity) for the four regions and varying model parameters (alkalinity, pCO2, gas transfer velocity, mixed layer depth, fraction of exported carbon/alkalinity) is computed. In addition, the cases with permanent and monthly alkalinity supply (repeated every year) are investigated.Guinehut, S., A.-L. Dhomps, G.Larnicol and P.-Y. Le Traon (2012). High resolution 3-d temperature and salinity fields derived from in-situ and satellite observations, Ocean Sci., 8, 845–857, https://doi.org/10.5194/os-8-845-2012.Landschützer, P., N. Gruber and D.C.E. Bakker (2020). An observation-based global monthly gridded sea surface pCO2 and air-sea CO2 flux product from 1982 onward and its monthly climatology (NCEI Accession 0160558). Version 6.6. NOAA National Centers for Environmental Information. Dataset. [2021-27-09]
Multiproxy constraints on recovery processes during the hyperthermal Toarcian Oceanic Anoxic Event
Authors: Fantasia Alicia , Adatte Thierry , Spangenberg Jorge E. , Mattioli Emanuela , Regelous Marcel , Salazar Christian , Millot Romain , Bodin Stéphane , Letulle Thomas , Rogov Mikhail , Suan Guillaume
Published: February 2023

Extreme and rapid climatic and environmental perturbations have punctuated Earth history. The causes and consequences of these past global-change events are relatively well constrained, but how the system can naturally recover through feedbacks remain largely unconstrained. The Toarcian in the Early Jurassic is an ideal time interval to understand the response of Earth system to rapid climate change. Indeed, it was marked by one of the most extreme hyperthermal events of the Phanerozoic accompanied by major environmental changes, named the Toarcian Oceanic Anoxic Event (T-OAE, ca. 183 Ma). Most studies have focused on the triggering mechanisms and the palaeoenvironmental response, whereas the recovery phase has been less studied. Increased chemical weathering of silicate rocks and burial of organic carbon are the two primary natural mechanisms generally proposed as negative feedbacks controlling the recovery. However, to date, the response of these feedbacks, their efficiency, and their timing are still uncertain, hampering an accurate view of the carbon cycle-climate dynamics. This study aims to tackle this lack of empirical data by providing a multi-proxy dataset combining sedimentological observations, mineralogical and geochemical analyses. Four worldwide distributed sites have been selected for this study: Fontaneilles in France (Grand Causses Basin), Vilyui in Siberia (Siberian Basin), Agua de la Falda in Chile (Andean Basin), and Ait Athmane in Morocco (High Atlas Basin). Our high-resolution carbon isotope records allow us to correlate the studied sites to trace the global carbon cycle dynamics in the aftermath of the Toarcian event. Lithium isotope ratios are used to trace global weathering rates and to understand processes that control the long-term carbon cycle. Our results indicate that higher silicate weathering rates during the Toarcian hyperthermal likely helped the climate system recover and return to cooler climatic conditions. High mercury and tellurium concentrations recorded after the T-OAE interval suggest that protracted Karoo-Ferrar volcanic activity may have played a role in the recovery.
Subsurface temperature anomaly observed by Argo floats during the 2022 Mediterranean Marine heatwave
Authors: Gallo Antonella , Pirro Annunziata , Martellucci Riccardo , Kubin Elisabeth , Mauri Elena , Notarstefano Giulio , Pacciaroni Massimo , Bussani Antonio , Menna Milena
Published: February 2023

Marine Heatwaves are periods of persistent anomalously warm ocean temperatures, which can have significant impacts on ecosystems as well as coastal communities and economies. Their magnitude and frequency have increased over the last couple of decades as shown by surface satellite observations, but our understanding of the structure of their depth is still limited. The present work investigates the temperature anomaly of the 2022 Marine Heatwave in the Mediterranean Sea down to 2000 m depth using in-situ Argo floats observations. The Ocean Heat Content anomaly of 2022, estimated with respect to a float-derived climatology relative to the period 2001-2020, was used to define the regions most affected by warming in different layers. In these areas (North-Western Med, Central Ionian Sea, Southern Adriatic) float profiles were divided in three categories, based on the heat vertical penetration: category 1 (shallow, 0-150 m), category 2 (intermediate, 150-800 m), category 3 (deep, > 800 m). Profiles from category 1 showed near-zero or slightly negative temperature anomaly in a thin layer between 50 m and 150 m of depth, while displaying a warming below the intermediate layer. Profiles characterized by larger heat vertical penetration (categories 2 and 3) were mainly located within mesoscale or sub-basin scale structures and showed the largest positive temperature anomaly in the surface layer and in the thermocline. All profile categories exhibited a warming between 200 and 800 m depth. This study highlights the impact of Marine Heatwaves on the Mediterranean subsurface layers and the influence of ocean circulation on their characteristics, opening the way to describe their consequences on the deep ecosystems. 
Future proglacial lake evolution and outburst flood hazard in south Iceland
Authors: Wells Greta H. , Sæmundsson Þorsteinn , Guðmundsson Snævarr , Pálsson Finnur , Magnússon Eyjólfur , Hermanns Reginald L. , Aðalgeirsdóttir Guðfinna
Published: February 2023

Arctic regions are warming at more than double the global average rate with significant impacts on glaciers and hydrologic systems. Iceland is on the front line of this rapid climate change, with a predicted loss of ~20% of its current ice cap volume by 2100. Much of this meltwater is stored in proglacial lakes at outlet glaciers, which are at risk of draining in glacial lake outburst floods (GLOFs). Most contemporary outburst floods in Iceland have been triggered by subglacial eruptions and geothermal activity; however, GLOFs resulting from mass movement events into lakes are an emerging—yet understudied—hazard. Many of Iceland’s proglacial lakes form in overdeepened basins, storing large volumes of meltwater; expanding lake extent creates more surface area for mass movements to enter; and retreating glaciers remove support from valley walls, increasing rockfall and landslide risk. Several large rockfalls have fallen onto glaciers in the past decades; however, these events may enter lakes as glacier retreat progresses and lakes expand.We investigate this emerging hazard by predicting proglacial lake evolution and assessing GLOF risk under a future warming climate at three sites in south Iceland. This presentation focuses on the proglacial lake at Fjallsjökull, an outlet glacier of the Vatnajökull ice cap. We present lake volume changes since 1980, derived from bathymetric surveys and mapped lake surface areas. We then estimate future lake volume and extent changes from the present until 2100 based on: 1) local topography derived from bathymetric mapping, ArcticDEM, and subglacial topography from radio-echo sounding surveys; and 2) projected glacier retreat under different climate warming scenarios. Next, we identify potential hazards from mass movement events entering the lake at its current and future extents based on field mapping and remote sensing imagery. Finally, we discuss implications of a glacial outburst flood on downstream communities, infrastructure, and tourism, laying the foundation for future work on hazard assessment and flood modeling. This site is an excellent pilot study for this emerging hazard in Iceland and has significant potential for application to other Icelandic and Arctic glacial lakes.
Major shifts in sediment provenance revealed by a Pleistocene drill core record from the Eastern Alps (Austria)
Authors: Schmalfuss Clemens , Firla Gustav , Neuhuber Stephanie , Lüthgens Christopher , Schaller Sebastian , Schuster Bennet , Fiebig Markus
Published: February 2023

The valley network of the Austrian Eastern Alps was shaped by a complex interplay of tectonic, fluvial, glacial, and karst processes. The sedimentary infill of a glacially overdeepened structure in the Bad Aussee basin provides an excellent opportunity to reconstruct the regional landscape evolution. A drill core, which is investigated as a part of the ICDP (International Continental Scientific Drilling Program) project DOVE (Drilling Overdeepened Alpine Valleys), recovered 880 m of Pleistocene sediments. This unique record shows a succession of subglacial, (glacio-)fluvial and lacustrine deposits.In this study, we complement sedimentological and geochemical analyses of the drill core material with data obtained from nearby outcrops to investigate the provenance of the basin infill. Petrographic analyses show that metamorphic rocks such as mica schists and gneisses, likely derived from the central Alpine crystalline units to the south of the Enns valley, make up the majority of the gravel fraction over large sections of the succession. As today’s catchment of the river Traun, which drains the Bad Aussee basin, is largely composed of carbonate rocks, major changes in the regional drainage network during the Pleistocene glacial-interglacial cycles can be assumed. Currently ongoing geochronological investigations using a combination of luminescence and cosmogenic nuclide burial dating will help constrain the timing of sediment deposition and improve our understanding of the regional Quaternary topographic evolution.
Application of the wave telescope to Vlasiator simulations using multi-scale spacecraft configurations
Authors: Schulz Leonard , Plaschke Ferdinand , Glassmeier Karl-Heinz , Motschmann Uwe , Narita Yasuhito , Palmroth Minna , Roberts Owen , Turc Lucile
Published: February 2023

The wave telescope is a multi-spacecraft method that uses multi-point magnetic field data to estimate a spectrum in k-space, allowing for the detection of waves as well as turbulence. So far, the wave telescope has been applied to the Cluster and MMS four-spacecraft missions around Earth. In the future, it can be used for multi-scale plasma missions incorporating larger numbers of spacecraft. Such are the accepted Helioswarm mission as well as the proposed Plasma Observatory. Due to the more complicated nature of the wave telescope analysis of multi-scale spacecraft configurations, there is a need to study such systems beforehand using as-realistic-as-possible artificial data. Such an artificial 2D or 3D dataset can be provided by Vlasiator, a Hybrid-Vlasov global magnetospheric simulation treating electrons as a fluid and protons being described by distribution functions. We apply the wave telescope to spacecraft configurations both different in number and position and determine the quality of detection of foreshock plasma waves simulated by Vlasiator.
A dimensionless parameter to predict spontaneous convective aggregation onset in a idealized stochastic-diffusive model of radiative-convective equilibrium
Authors: Tompkins Adrian , Biagioli Giovanni
Published: February 2023

Cloud resolving models run to equilibrium in idealized simulations of radiative-convective equilibrium often show the deep convection spontaneously transitioning from random organization to a state where convection in aggregated into clusters.  This results in a drier mean state and aggregation could be important for climate sensitivity, and is missing in classical parameterization schemes.  However, the onset and nature of the equilibrium, and the sensitivity to lower boundary conditions, differs dramatically between models that use different representations of moist physics and diffusion parameterizations, and varying dynamical cores.  In order to shed light on this, we develop a highly idealized, spatially explicit, stochastic reactive-diffusive model for the column relative humidity in the tropics.The model is run to equilibrium and it is found that, depending on the model parameter settings and experimental framework, it can produce equilibrium states where the convection remains random, or states where the convection is highly aggregated. Many results of the full-physics models are reproduced, such as their sensitivity to model resolution and domain size, with aggregation more likely using coarse grid sizes and larger domains. The simple model thus allows to explain these sensitivities of the full physics models, with convective nearest-neighbor distances constrained to decrease with smaller domains or higher resolution, which reduces the spatial heterogeneity of column humidity and makes aggregation less likely.  Expanding on these arguments, we use dimensional analysis to combine the model parameters that describe how sensitive convection is to humidity, the subsidence drying rate, and the spreading of humidity by advection and diffusion processes, along with the domain size and resolution.  Using large ensembles of over 1000 simulations, we demonstrate that aggregation occurs at a precise critical value of the resulting dimensionless parameter, which will refer to as the aggregation number.   We suggest that the aggregation number could prove useful to diagnose the differences between full physics models of the atmosphere. 
Effect of afforestation on the organic carbon stock of soils
Authors: Bidló András , Csorba Mátyás , Balázs Pál , Végh Péter , Horváth Adrienn
Published: February 2023

Since 1922, the territorial proportion of forests has increased from 12% to 22% due to large-scale afforestation in Hungary. These planted forests bind huge amounts of carbon dioxide from the atmosphere. The sequestered carbon is partly stored in the above-ground biomass of forests in the form of organic matter. At the same time, a similar amount of carbon can be found underground. The research aims to assess the effect of afforestation on the amount of organic carbon stored in the soil (SOC).During our investigations, we collected samples from 3 study areas from the Hungarian Great Plain. We compared the soil of the poplar and acacia forests in the sample areas with the grassland soils located directly next to these plantations. By the natural conditions, the pH of forest (7.75 and 8.29 pH(H2O)) and grassland (8.01 and 8.45 pH(H2O)) samples was weakly alkaline/alkaline. We measured a lower pH value in case of forests, which clearly shows the leaching effect in the forest soils. The average humus content of the tested soil samples was 0.94%. The lowest measured value was 0.09%, while the highest was 4.21% which clearly showed that dry sandy soils have a low organic matter content.The soil and the litter cover contain 7 to 37 tons SOC/ha. The differences between the studied areas were very large. The carbon stock of the soils was higher in forest stands in every case. This shows that in long term the afforestation increases the amount of carbon stored in soils compared to grasslands.This article was made in frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. 
Multifractal analysis of Cn2 scitillometer data and consequences for evapotranspiration estimates in urban areas
Authors: Zhu Sitian , Gires Auguste , Maksimovic Cedo , Tchiguirinskaia Ioulia , Schertzer Daniel
Published: February 2023

The cooling impact of green roofs is highlighted in the context of urbanisation and urban heat island (UHI) effect. And it is usually described and quantified by evapotranspiration (ET) processes. Understanding ET process is the key to optimize cooling effect. ET estimation can be achieved either directly (weighing lysimeters) or indirectly (e.g., Penman-Monteith equation). Micro-meteorological approaches have been developed in recent years. Among which scintillometer can evaluate ET by its measurement parameter Cn2 (which corresponds to the fluctuations of air refractive index n ) in combination with surface energy balance (SEB) and Monin-Obukhov similarity theory (MOST) . Hence, Cn2 improvement in Cn2 data would result in better ET estimation. But it is often overlooked and very little research has focused on it. In this project, the research area lies on the top of the Carnot and Bienvenüe buildings in Ecole des Ponts Paristech. Covering an area of ​​1 ha, it is a wavy and vegetated large green roof, known as the Blue Green Wave (BGW). Data from a large aperture scintillometer (LAS) with 10-minute time step during December 2019 and January 2020 on BGW is used in this study. Three estimates of Cn2(Cn2_UCn2, Cn2_PUCn2 and Cn2_Var) were analysed with structure function and universal multifractal model (UM). Such framework has been widely use to characterize geophysical fields extremely variable across wide range of space-time scales. There are two relevant parameters in an UM model, the mean codimension of intermittency C1≥0and multifractality index 0≤α≤2. α=0, indicates monofractal; α=2, indicates log-normal model. Data in UM framework is analysed by Trace Moment (TM) method and Double Trace Moment (DTM) method. All of estimates demonstrated scale invariance, which could be used for upscaling and downscaling. Cn2_Var performed well even during measurement malfunction, but UM analysis showed it was contradictory to the hypothesis of lognormality. It implies the way it calculates Cn2_Var need some revisions and an assessment of the scintillometer could be achieved by analysing Cn2. This research provides a complete grasp of the properties of Cn2 and sets the stage for its future application in precise ET estimates. 
The composition of asbestos bodies in human lungs
Authors: Bardelli Fabrizio , Pacella Alessandro , Giacobbe Carlotta , Di Benedetto Francesco , Montegrossi Giordano , Borelli Violetta , Ballirano Paolo
Published: February 2023

The asbestos bodies (AB) form in the lungs as the result of an in vivo biomineralization process started by the alveolar macrophages in the attempt to isolate asbestos and become the actual interface between asbestos and the host organism. The AB are believed to be mainly composed of the Fe-proteins and mucopolyssaccharides. However, the presence of hydroxyapatite and Fe-oxy(hydro)oxides, other than ferrihydrite (the mineral core of ferritin), has also been proposed. We performed synchrotron X-ray diffraction (XRD) and absorption (XAS) measurements to unravel the Fe form in the AB and to check the crystallinity of the inner fiber. XRD results revealed the presence of goethite and that the inner fiber (crocidolite) maintained a high degree of crystallinity despite the prolonged stay in the lungs (>10y). XAS results, on the other hand, revealed the co-existence of ferrihydrite and goethite. The results are discussed in terms of the higher toxicity of goethite with respect to ferrihydrite.