bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructing Technosols: Prediction of soil hydraulic properties for binary mixtures – concept and application
Authors: Nehls Thomas , Willaredt Moreen , Andre Peters
Published: March 2024

Constructed Technosols are important for substituting natural soil material, such as peat and geogenic material, for use in urban green infrastructure. One characteristic of Technosols important to their role in urban green infrastructure, specifically with respect to urban water management, is their soil hydraulic properties (SHPs), depending on the composition of the constructed Technosols (e.g. their components and their mixing ratio). The diversity of possible components and the infinite number of mixing ratios practically prohibit the experimental identification of the composition needed to achieve suitable soil hydrological functions.In this study, we propose a compositional model for predicting the water retention curves (WRCs) of any binary mixture based on the measured WRCs of its two pure components only (basic scheme) or with one additional mixture (extended scheme). The unsaturated hydraulic conductivity curves (HCCs) are predicted based on the modelled WRCs. The compositional model is developed from existing methods for estimating the porosity of binary mixtures. The model was tested on four data sets of measured WRCs of different binary mixtures. The distribution of water and air in 50 cm high soil columns filled with these mixtures was predicted under hydrostatic conditions in order to assess their suitability for typical urban applications.The difference between the maxima of the pore size distributions ΔPSDmax (m) of the components indicates the applicability of the compositional approach. For binary mixtures with small ΔPSDmax, the water content deviations between the predicted and the measured WRCs range from 0.004 to 0.039 cm3 cm−3. For mixtures with a large ΔPSDmax, the compositional model is not applicable. The prediction of the soil hydraulic properties of any mixing ratio facilitates the simulation of flow and transport processes in constructed Technosols before they are produced (e.g. for specific urban water management purposes).The study has been published under https://doi.org/10.5194/hess-27-3125-2023, 2023.
Assessing different IPCC Tier Approaches for estimating Methane Emissions in Vietnamese Rice Agriculture
Authors: Nguyen Chien , Vo Thi Bach Thuong , Bui Phuong Loan , Mai Van Trinh , Nguyen Tanh , Butterbach-Bahl Klaus , Sander Bjoern Ole , Wassmann Reiner , Kiese Ralf , Kraus David
Published: March 2024

The IPCC provides three distinct protocols (Tier 1-3) that can be used for reporting on greenhouse gas (GHG) emissions under the UNFCCC. While Tier 1 and 2 use relatively straightforward methods based on global and region-specific emission factors, Tier 3 is more complex and uses process models for emission estimation. Although Tier 3 is considered to have higher accuracy potential, its complexity requires expert knowledge and extensive input data, which is often not available, hindering widespread adoption.This study critically evaluates all three Tier approaches for CH4 emissions from rice production in Vietnam, using the ecosystem process model LandscapeDNDC for the Tier 3 approach. As a first step, we evaluate all three approaches based on a comprehensive dataset covering 73 cropping seasons from 36 sites across Vietnam. On this basis, we show the extent to which Tier 3 performs better when considering commonly available information, and which information is most important to outperform simpler methods. As a second step, we present national CH4 emission inventories for each approach and show under which circumstances the approaches differ the most. We also present a web-based tool that improves the accessibility of Tier 3 applications for users who are not familiar with the application of a particular complex process model.Our findings aim to provide valuable insights into the effectiveness of UNFCCC reporting approaches, particularly the under-researched Tier 3.
3D interaction of tectonics with surface processes explains fault network evolution of the Dead Sea Fault
Authors: Brune Sascha , Heckenbach Esther L. , Glerum Anne C. , Granot Roi , Hamiel Yariv , Sobolev Stephan V. , Neuharth Derek
Published: March 2024

Releasing and restraining bends are complementary features of continental strike-slip faults. The Dead Sea Basin of the strike-slip Dead Sea Fault is a classical example of a releasing bend with an asymmetric, deep basin structure. However, the intrinsic relationship to its northern counterpart, the restraining bend that created the Lebanese mountains, remains unclear.Here, we present 3D coupled geodynamic and landscape evolution models that include both the releasing and the restraining bend in a single framework. These simulations demonstrate that the structural basin asymmetry is a consequence of strain localization processes, while sediments control the basin depth. Local extension emerges due to strength heterogeneities and a misalignment of faults and the overall stress field in an area where regional tectonics are dominated by strike-slip motion. Furthermore, we reveal a crustal thinning and thickening pattern that intensifies with surface process efficiency. Along-strike deformation is linked through coupled crustal flow driven by gravitational potential energy which is opposed by deposition at the releasing bend and enhanced by erosion around the restraining bend. Due to the generic nature of our models, our results provide templates for the evolution of fault bends worldwide.
The September 2023 flood in Derna, Libya: an extreme weather event or man-made disaster?
Authors: Dente Elad , Armon Moshe , Shmilovitz Yuval
Published: March 2024

Storm Daniel, the deadliest recorded Mediterranean tropical-like (medicane) storm, led to severe floods in large parts of the eastern-central Mediterranean, including Greece and northern Libya. Extreme rainfall, reaching more than 400 mm day-1, triggered a flash flood in Wadi Derna (Libya)– an ephemeral river with a drainage area of 575 km2 that crosses the city of Derna at its outlet to the Mediterranean Sea. Historical measures to mitigate flood risks included dam construction in the Wadi Dernah basin since the 1970s. However, during Storm Daniel, at least two of the dams were breached, resulting in a devastating flood that inundated much of the city of Derna, with over 4,000 casualties, 8,000 missing persons, and the displacement of tens of thousands. The devastating event was the focus of media coverage for a long time, but questions regarding the role of dams and their collapse remain open, and are relevant for other dammed regions as well: How extreme was the storm? How extreme the flood would have been if the dams had not been breached? What would the outcomes of the flood look like if dams were not built in the first place?To analyze the characteristics of the storm over Wadi Derna, the catchment’s hydrological response, and the impact of the flood on the city of Derna, we integrate various datasets and models. Satellite-based precipitation estimations (IMERG) were used to quantify spatiotemporal storm properties and the catchment-scale rainfall, which were fed into the KINEROS2 hydrological model to quantify surface runoff upstream of the collapsed dams. The modeled flood hydrograph is then fed into a 2D hydraulic model (HEC-RAS) to test three end-member scenarios: (a) dam filling, overflow, and collapse, (b) dam overflow but no collapse, and (c) no dams exist in the wadi. This combination of methods reveals that the peak discharge during the flood was ~1,400 m3 s-1, just below the expected maximum extreme flood for this region. In the dam-collapse scenario, the populated flooded area is 40% larger than the no-dam scenario. These results emphasize the anthropogenic influence of damming natural streams on flood impacts. Given the high variability of precipitation in arid and semi-arid areas and the projected increase in extreme precipitation intensity with climate change, the Wadi Derna flood should serve as a warning sign for other populated areas downstream of a man-made dam in similar environments.
Influence of different land cover types on land surface temperature - case study of the Lucknow city in India
Authors: Szrek Aleksandra
Published: March 2024

With the increase of urbanization, the urban heat island phenomenon is becoming more noticeable and concerning. This effect occurs when the temperatures are higher in urbanized areas than in suburban and rural areas. The aim of this study is to analyze the influence of different land cover types on the land surface temperature (LST) and the surface urban heat island (SUHI) effect. The study was conducted on imagery acquired in September by Landsat 8 OLI TIRS satellite. The selected area was the city of Lucknow (India) and its surroundings. The climate is subtropical, seasons are clearly distinguishable - winters are cold, summers are hot and dry. Land cover types were determined using supervised classification and Normalized Difference Vegetation Index. Land surface temperature was calculated. The influence of different land cover on LST and SUHI phenomenon was analyzed by using visual analysis, comparing average temperatures of land cover classes, creating temperature profile and calculating Urban Thermal Field Variance Index to analyze the intensity of SUHI.The type of land cover affects land surface temperature therefore has an impact on the SUHI phenomenon. Build-up areas show much higher land surface temperature than non-urban, vegetated areas. The spatial distribution of these forms of land cover, i.e. the cumulative built-up area forming the city and the green areas around the city, combined with the with their characteristic surface temperatures, result in an surface urban heat island effect. Average temperatures of non-natural surfaces are around 5°C higher than average temperatures of natural surfaces. UTFVI indicates that the intensity of SUHI phenomenon is the highest in build-up and bare soil land cover classes, and the lowest for vegetation and water areas. The intensity also varies within a single class, in urban areas UTVI is higher in the center and decreases toward the vegetation class. The LST values and temperature profile indicates that the higher temperature of non-natural land cover forms affects not only the increased temperature of the surface on which they are located but also the areas in the close neighborhood. Temperature within the same land cover class of agricultural areas and meadows areas is higher when measured in the vicinity of the urban class.
Assessing the Spatiotemporal Variability and Complementarity of Renewable Energy Resources across Europe
Authors: Bibi Amna , Marzeion Ben , Shafeeque Muhammad , Lohmann Gerald
Published: March 2024

Europe's energy transition towards renewable sources is imperative for achieving sustainability and mitigating climate change. However, the intermittency of solar and wind power necessitates a detailed evaluation of their combined potential. This study analyzes the spatiotemporal distribution and variability of solar and wind power resources across Europe from 1979-2022, using ERA5 reanalysis data.Empirical Orthogonal Function (EOF) analysis is used to characterize the spatiotemporal patterns of variability in irradiance and wind speed up to multidecadal timescales. Also, the variance of the estimates of the capacity factor (CF, i.e., electricity generation normalized to the installed capacity) is compared with EOF patterns.Results show that the leading three modes of EOF represent the most variance in spatial distribution of irradiance and wind speed over Europe, with significant interannual and interdecadal fluctuations influencing spatiotemporal distribution. The temporal variance for offshore and onshore wind exhibits larger spatial heterogeneity. The spatial heterogeneity of the variance of solar CF is lower than that of wind power CF, but its amplitude is much higher in most regions. There is a negative linear correlation between the variance and mean of CF for both solar and wind power.Southern Europe shows the lowest intermittency in solar power, while eastern and northern Europe exhibit a lower intermittency of onshore wind. Offshore wind potential is high over the Norwegian and Mediterranean Seas. We also identify areas of maximum complementary between solar and wind power resources, attempting to use large-scale datasets and established knowledge of patterns of climate variability to fulfill local-scale renewable energy requirements best. Future research will focus on developing advanced hybrid models to integrate diverse renewable energy sources, exploring their synergistic potentials.
Using Ensemble Ocean Currents for Drift Predictions
Authors: Dagestad Knut-Frode , Rohrs Johannes , Idzanovic Martina , Rikardsen Edel , Hope Gaute
Published: March 2024

Predicting the drift of objects and substances in the ocean is relevant for several important applications, such as assisting search and rescue and oil cleanup operations, and for understanding and analysing the drift and distribution of plastics or fish eggs and larvae in the ocean.The largest uncertainty of such simulations is normally due to currents obtained from ocean models, in particular for the short-term applications such as oil spill accidents and search and rescue operations. Assimilation of observations help make the ocean models more precise, but unfortunately only a limited amount of observations with high spatial resolution are available.Trajectory models compensate for the imprecise forcing data by adding horizontal diffusivity, providing a spatial spread to encompass the most likely drift. However, a more realistic spread can be obtained by running an ensemble ocean model, where current fields are perturbed in a more physically sound way.In this study, we are analysing a set of ocean surface drifters released in the Fram Strait and Barents Sea, within the domain of an 24 member ensemble setup of ROMS with 2.5km pixel size, run operationally by MET Norway.We explore and demonstrate methods to combine the ensemble current fields to improve the predictability of the drifter trajectories. Also, we demonstrate a method for further improvement of future predictability for situations where a recent part of the drift trajectory is known, e.g. for an object with GPS tracking that has lost connection.
Occurrence of multi-layer clouds and ice-crystal seeding in the Arctic observed by Radar and radiosondes
Authors: Achtert Peggy , Seelig Torsten , Tesche Matthias , Wallentin Gabriella , Hoose Corinna
Published: March 2024

While prior research on Arctic clouds has predominantly focused on single-layer clouds, the presence of multi-layer clouds in the Arctic holds significance. In such complex atmospheric systems, upper-level clouds can exert influence on the phase of lower clouds. A notable scenario occurs when ice crystals descend from higher altitudes into supercooled liquid water clouds, triggering the formation of mixed-phase clouds.Our project is dedicated to investigating the occurrence of multi-layer clouds and their seeding, employing a combination of radiosonde and cloud radar observations. We will share findings from various locations, including research stations in Ny Alesund and the ARM North Slope of Alaska site, as well as insights from research cruises in the Arctic. Data from several research cruises were utilized in this study, namely MOSAiC (2019/20), Arctic Ocean 2018, and the ACSE 2014 campaign.In addition, for the MOSAiC campaign, we employ back trajectories from various cloud levels and clear sky regions above the clouds to gain deeper insights into the occurrence and formation of multi-layer clouds. Our focus extends to different seasons, particularly emphasizing the Arctic melt and freeze-up periods.
High-Resolution Tsunami Simulations including Land Use-Dependent Variable Friction Along Puerto Rico's Coast
Authors: Sánchez-Linares Carlos , Macías Sánchez Jorge , Porras Hernán , Huérfano Víctor
Published: March 2024

This study integrates high-resolution tsunami simulations with land use-dependent variable friction across the entire coastal region of Puerto Rico. By using the Tsunami-HySEA model, developed by the EDANYA Research group at the University of Malaga, this research transcends traditional practices, exploring the interplay between terrain characteristics and tsunami dynamics through the incorporation of variable friction. The execution of high-resolution simulations covering the entire coast of Puerto Rico represents a computational and scientific challenge unprecedented in prior research, reinforcing the applicability of this study.Computational topo-bathymetric grids are constructed to create a coherent model, smoothing irregularities in topo-bathymetric data. Provided by the Puerto Rico Seismic Network, these data have been processed for optimized numerical simulations. The study employs five sets of nested grids, corresponding to different regions (Northeast, Northwest, East, West, and South) of Puerto Rico, and within each configuration, four nested grids with resolutions ranging from 480 meters to 7.5 meters facilitate simulations with varying levels of detail. This strategy optimizes computational resources and ensures precise results in specific coastal areas. The high-resolution discretization, at 7.5 meter per pixel, spans the entire 1,100 km coastline of Puerto Rico. Additionally, simulations have been conducted for 29 distinct seismic sources, comparing this approach to the traditional constant friction approach with Manning coefficient set at 0.03.The influence of the Manning coefficient is evident in its effects on velocities, momentum flux, and, on the inundation area extension. Understanding the different land uses is crucial for accurately analyzing the effects of a tsunami on the coast and predicting the magnitude of the resulting inundation. The topography, vegetation, and structures built in coastal areas can significantly modulate wave propagation and water depth inland. Identifying these variations in land uses allows for a more precise planning of tsunami mitigation and response measures, as well as a detailed assessment of vulnerable areas.AcknowledgesThis contribution was supported by the Center of Excellence for Exascale in Solid Earth (ChEESE-2P) funded by the European High Performance Computing Joint Undertaking (JU) under grant agreement No 101093038 and by the EU project “A Digital Twin for Geophysical Extremes” (DT-GEO) (No: 101058129). The authors thankfully acknowledges the computer resources at CTE-Power and the technical support provided by Barcelona Supercomputing Center (AECT-2023-3-0017 - Tsunami Hazard Assessment for Puerto Rico. A first study of variable friction coefficient with Tsunami-HySEA)
Comparison of several approximation schemes on the Cubed Sphere
Authors: Croisille Jean-Pierre , Bellet Jean-Baptiste , Brachet Matthieu
Published: March 2024

Approximation, interpolation and quadrature are questions of fundamental importance for atmospheric and oceanic problems at planetary scale. Computation with spherical harmonics on the sphere is an old mathematical topic; it has a particular interest in geosciences, and is still an active field of research. In this poster, we will show numerical comparisons of several approximation schemes, with a special focus on the Cubed Sphere grid. We test hyperinterpolation, weighted least squares, and interpolation on a series of test functions with various smoothness properties. Our last results include the derivation of explicit formulas for optimal quadrature rules on low resolution Cubed Spheres.[1] J.-B. Bellet, M. Brachet, and J.-P. Croisille, Interpolation on the Cubed Sphere with Spherical Harmonics, Numerische Mathematik, 153 (2023), pp. 249-278.[2] J.-B. Bellet and J.-P. Croisille, Least Squares Spherical Harmonics Approximation on the Cubed Sphere, Journal of Computational and Applied Mathematics, 429 (2023),  115213.[3] C. An and H.-N. Wu, Bypassing the quadrature exactness assumption of hyperinterpolation on the sphere, Journal of Complexity, 80 (2024), 101789.
Palaeohydrological reconstruction of the Eastern Mediterranean Sea during the Eemian
Authors: Gao Guohui , Colin Christophe , Siani Giuseppe , Dapoigny Arnaud
Published: March 2024

The Mediterranean Sea's thermohaline circulation, sensitive to global climate changes, influences the Atlantic Meridional Overturning Circulation (AMOC) and the occurrence of sapropel layers in Mediterranean sediments. While sapropel formation is attributed to stagnant deep-water conditions and increased biological production during specific orbital cycles, debates persist concerning the complex interaction between high and low latitude climatic changes, circulation dynamics, and sapropel formation. We have investigated the hydrological dynamics of the eastern Mediterranean Sea during the Eemian using neodymium isotopes on foraminifera and other geochemical proxies. Cores from the southeastern Aegean Sea were compared with data from other Mediterranean regions to reconstruct water circulation patterns. Foraminiferal eNd records permit to identify two distinctive phases in the circulation patterns within the Sapropel S5. Initially, a large influx of freshwater causes water stratification, preventing the formation of deep-water layers and leading to localized signals observed in different cores. Cores located in the southern Mediterranean Sea exhibit prominent neodymium radiogenic signatures influenced by the Nile inputs. Conversely, cores positioned in the northern Mediterranean displays minimal Nile influence due to their more northerly location. During the deposition of the Sapropel S5, slight decreasing of sea levels and winter temperatures favored the formation of deep-water masses in the northern region, increasing basin-wide circulation. This enhanced circulation facilitates the transfer of radiogenic lithogenic Nd from the Nile to the northern part of the Eastern Mediterranean Sea. This change in circulation patterns highlights the influence of climate change on the deep hydrodynamics of the Eastern Mediterranean during the Eemian. Our data indicate for the first time that during the deposition of the sapropel S5, εNd not only exhibited vertical disparities and stratification but also shown noticeable large lateral variations in the Eastern Mediterranean Sea. Our new results highlight the importance of studying several cores in order to unravel the hydrodynamics on a basin scale and to elucidate the complex interactions within the Nd isotopic composition between freshwater input, circulation dynamics and fluvial sediment discharges in the eastern Mediterranean Sea during the last interglacial period.
Regionalisation methods for the designation of areas with groundwater nitrate pollution in Germany
Authors: Brenning Alexander , Suesse Thomas
Published: March 2024

The designation of nitrate-polluted areas for groundwater protection based on national directives implementing the EU Nitrates Directive (91/676/EEC) in Germany requires the use of geostatistical or deterministic regionalization methods. The objective of this study was to assess the applicability and propose a suitable methodology for a possible national-scale area designation based on an in-depth problem analysis and empirical as well as theoretical model assessments, which identified shortcomings, uncertainties and possible biases in the methods used until now.Suitable methods must not only be able to identify exceedance regions – as opposed to simply regionalizing nitrate concentration; they also need to take into account spatial heterogeneity and adequately represent distributional characteristics across a variety of hydrogeological settings. This requires the incorporation of ancillary information in the form of quantitative and categorical spatial predictors representing hydrogeological and general environmental conditions, but not emissions estimates in the present regulatory setting.Kriging with external drift, geostatistical regression-kriging methods and conditional geostatistical simulations offer an established methodological toolbox that fulfils these requirements and enables transparent decision-making. These models consist of linear, potentially nonlinear spatial trend components and geostatistical interpolation components, which can be further differentiated based on hydrogeological regions to account for heterogeneity. An unbiased estimate of the total exceedance area with nitrate levels >50 mg/l can be obtained from these models and accounted for in the decision-making process. An empirical comparison highlights possible biases in the size of exceedance areas obtained with traditional approaches that ignore local prediction uncertainty and focus on spatial prediction of nitrate concentration. Potentials and challenges of combining geostatistical techniques with nonlinear machine-learning models in a regulatory context are discussed.
A multi frequency altimetry snow depth product over the Arctic sea ice
Authors: Carret Alice , Fleury Sara , Di Bella Alessandro , Landy Jack , Lawrence Isobel , Laforge Antoine , Kurtz Nathan , Garnier Florent
Published: March 2024

Since more than 10 years, CryoSat-2 (CS2) has observed and monitored the Arctic Ocean, providing unprecedented spatial and temporal coverage. Satellite altimetry enables to measure sea ice thickness, one essential variable to understand the sea ice dynamics. Numerous sea-ice products developed by the community showed the skills of CS2 to retrieve sea-ice thickness. Nevertheless, several questions remain to better quantify the quality of the measurements. One of them is to better assess the snow depth, a key parameter to obtain the sea ice thickness. In 2018, ICESat-2 mission was launched carrying a LIDAR altimeter. We took advantage of the difference of penetration in the snow layer of laser and Ku-Band altimetry to compute a snow depth product covering the ICESat-2 period. This product is then validated and compared to in situ datasets, reanalysis, models and other snow depth products from satellite missions such as SARAL. Results are quite good concerning the comparison to in situ datasets giving us confidence in the product reliability. In July 2020, the orbit of CryoSat-2 was raised, as part of the CRYO2ICE project, to coincide in space and time to tracks from NASA high resolution altimeter ICESat-2 over the Arctic ocean. This is a unique opportunity to benefit from along-track colocalised data. We present here a methodology to compare ICESat-2 and CryoSat-2 along coincident tracks and compare the resulting snow depth product to gridded products. The lack of in situ measurements is one of the main limitations to analyze the along-track product contribution. Finally we focus on the advantages of combining laser and Ku-band altimetry to lower the uncertainties. The snow depth uncertainties of our product are about 6 cm on average. This ESA-supported study should help prepare the Copernicus CRISTAL mission, which will include a Ka/Ku dual-frequency altimeter for the first time.
Improving snowpack simulation at slope-scale resolution with machine learning and geostatistical downscaling of observed and forecasted weather data.
Authors: Raparelli Edoardo , Tuccella Paolo
Published: March 2024

The snowpack plays a fundamental role in regulating the global climate thanks to its high albedo and thermal insulation properties, and for many regions of the world it also has very local and important impacts. Indeed, the snow is an important water reservoir, storing the water in solid state during cold months, and releasing it in liquid state during warmer months. But the snow is also the necessary condition for the development of rural places which base their economy on winter sports. However, a certain risk is always associated with snow when it deposits on the ground, since the snow can slide down, creating avalanches which may cause several damages to the local flora, fauna, buildings and infrastructures. Typically, the conditions that allow the occurrence of snow avalanches span from the point scale to the slope scale, and depend on the snowpack properties. Kilometer-resolution numerical models are not able to reproduce the slope-scale variability of the snowpack properties because of the complex interaction between the atmospheric flows and the topography at finer scale. To address this limitation, we apply several algorithms to downscale 1 km horizontal resolution WRF atmospheric simulations to 500 m horizontal resolution in order to force the snow cover model Alpine3D with more representative weather data. Additionally, we train a fully convolutional neural network to downscale 10 km resolution IMERG precipitation data to 1 km horizontal resolution, further downscaled to 500 m. Furthermore, 2m temperature point observations are interpolated at 500 m resolution using geostatistical techniques. Finally, we force Alpine3D with a combination of forecasted and observed data, obtaining improved simulation results compared to using only forecasted weather data. This implies that the use of a combination of simulated and observed weather data is particularly promising for the estimation of the snowpack properties at slope-scale resolution in regions characterized by complex topography, providing more reliable information for risk mitigation, and sustainable development of snow-prone areas.
Quantifying the human-induced climate change impact on heat-related mortality events in Europe with Extreme Event Attribution Methods 
Authors: Beck Thessa M , Gudmundsson Lukas , Schumacher Dominik L , Seneviratne Sonia I , Achebak Hicham , Ballester Joan
Published: March 2024

Numerous Extreme Event Attribution (EEA) studies have consistently shown that human-induced climate change has increased the likelihood of extreme heat events. The increasing relevance of these studies in the context of climate litigation underscores the demand for the quantification of climate change impacts. Heat, as the primary contributor to weather-related mortality on the European continent, has caused more than 61,000 heat-related deaths in Europe during the 2022 summer. We carry out this proof-of-concept study in which we apply Extreme Event Attribution methods combined with epidemiological models to quantify how anthropogenic warming has influenced extreme heat-related mortality events in Europe. In contrast to most health impact studies, we utilize open-access mortality data from Eurostat, which is available in near-real time.Because of the complex, non-linear relationship between temperature and mortality, we conduct separate Extreme Event Attribution analyses for (i) temperature extremes and (ii) associated heat-related mortality events in 232 distinct administrative regions spanning over 35 European countries. Our findings reveal that the probability of the maximum weekly values observed in 2022 has increased 12-fold [95th CI 3.51-147.15] for temperature and tripled [95th CI 1.02-18.63] for mortality compared to the pre-industrial baseline. Notably, we identify significant geographical disparities, e.g. in Spain the mortality risk is even 30 times higher [95th CI 3.33 – 1218.14] due to anthropogenic warming.We find a statistically significant trend in 70% [90%] of the regions at the 0.95 [0.90] significance level, and across all age and sex groups, except for women aged 65 years or less, indicating that anthropogenic warming affects almost the entire European population.This study establishes a foundation for subsequent analyses, not only for heat-related mortality events observed on different temporal and spatial scales but also for enabling an examination of other weather events and associated health impacts. By combining climate sciences and techniques with epidemiology and health data, it is possible to calculate the contribution of climate change to changes in health risks and mortality burdens by sociodemographic categories, such as sex, age, socioeconomic level, or comorbidities, especially in vulnerable groups. This transdisciplinary work has to potential to provide key information for climate-related health lawsuits and opens the door to inter- and transdisciplinary perspectives on how to integrate geoscience and epidemiology insights in litigation.
Influence of Subtropical Jets on the Equatorial Spectrum: implications for future changes in Kelvin waves and MJO variance
Authors: Bartana Hagar , Garfinkel Chaim , Schwartz Chen , Shamir Ofer , Rao Jian
Published: March 2024

Projected changes of tropical Convectively Coupled Equatorial Waves (CCEWs)  due to increased greenhouse gases, and the dynamical mechanism that forces those changes, are investigated in 13 state-of-the-art models from phase 6 of the Coupled Model Intercomparison Project (CMIP6).   The equatorial wave spectrum in the historical simulation from most of these models quantitatively (and even quantitatively) resembles that observed, a remarkable improvement from CMIP5. Most models project a future increase in power spectra for the Madden-Julian Oscillation  (MJO), while nearly all project a robust increase for Kelvin Waves (KW). In contrast, the power spectrum weakens for most other wavenumber-frequency combinations, including higher wavenumber Equatorial Rossby waves (ER). In addition to strengthening, KW also shift toward higher phase speeds (or equivalent depths). These changes are even more pronounced in models with smaller biases in their historical simulations.

The qualitatively different projected response of the different CCEWs (e.g., KW strengthening vs. ER weakening) suggest that dynamical forcings have an important role in the physical mechanism of the changes. This hypothesis is tested using targeted simulations of the Model of an Idealised Moist Atmosphere (MiMA) in which we impose perturbations in upper-troposphere zonal winds mimicking projected end-of-century changes in wind. These simulations demonstrate that future changes in KW and the MJO strongly depend on changes in the South Pacific subtropical jet. A similar dependence is also evident in the CMIP6 models. However, the winds in the south Pacific subtropical jets in the historical simulation of these CMIP6  models  are highly biased, and models with a stronger change in the jet tend to project a stronger intensification of both the MJO and KW. It is therefore necessary to account for this bias in the subtropical winds in order to provide more reliable projections of the KW and the MJO.
Vegetation responses in East Asia to rapid climate changes: comparisons among the Younger Dryas event, the 8.2ka event, and the 4.2ka event
Authors: Li Huan , Chen Chunzhu , Zhao Wenwei , Zhao Yan
Published: March 2024

Investigations of past biotic responses to rapid climate shifts are useful for developing biological scenarios that may result from future climate change. Vegetation responses to the Younger Dryas (YD) cold climatic reversal, the 8.2 ka cooling event, and the 4.2 ka event are of considerable interest. In this paper, we conduct model simulations of vegetation responses to these rapid climate changes over East Asia, and compare them with pollen-based vegetation records. Our aims were to investigate the vegetation responses to rapid climate changes with different magnitudes and to analyze dominant impact factors on vegetation in East Asia. Our results reveal that all major Plant Functional Types responded to the climate changes, but the magnitude, timing, and impact of their responses varied, with most changes in vegetation composition rather than vegetation type succession. In addition, it was found that after the abrupt cooling events the vegetation did not always recover to the state simulated before the perturbation, suggesting that different vegetation compositions may occur under similar climate conditions. Notably, there was a latitudinal gradient in the magnitude of these cold events in East Asia and in the resulting vegetation response, indicating a more pronounced vegetation responses to the severe cooling in the north and weaker responses to less cooling in the south. Changes in temperature exerted a major influence on the vegetation dynamics in the most high latitude regions, and changes in both temperature and precipitation were responsible for the vegetation changes at mid-to-high-latitudes. Vegetation compositions show a long-lasting effect of abrupt climate changes through eco-physiological and ecosystem demographic processes.
Investigating the Molecular-Scale Mechanism of Deposition Ice Nucleation on Silver Iodide Surfaces
Authors: Roudsari Golnaz , Lbadaoui-Darvas Mária , Welti André , Nenes Athanasios , Laaksonen Ari
Published: March 2024

Heterogeneous ice nucleation is a ubiquitous process in the natural and built environment. Deposition ice nucleation, according to the traditional view,, occurs in a subsaturated water vapor environment without the presence of supercooled water on the solid, ice-forming surface. This process is notably significant among the various ice formation mechanisms in high-altitude cirrus and mixed-phase clouds. Despite its significance, our understanding of the microscopic mechanism of deposition ice nucleation remains quite limited. This study introduces an adsorption-based mechanism for deposition ice nucleation through results from a combination of atomistic simulations, experiments and theoretical modeling.Silver iodide (AgI) particles prove highly efficient as ice-nucleating particles (INPs), commonly employed in rain seeding, and stand as one of the most potent laboratory surrogates for ice nucleation. In this study, AgI is used as a substrate for the simulations. The study involves a combination of grand canonical Monte Carlo and molecular dynamics (GCMC/MD) techniques to investigate deposition ice nucleation on AgI. We find that water initially adsorbs in clusters which merge and grow over time to form layers of supercooled water. Ice nucleation on silver iodide requires at minimum the adsorption of 4 molecular layers of water. Guided by the simulations we propose the following fundamental freezing steps: 1) Water molecules adsorb on the surface, forming nanodroplets. 2) The supercooled water nanodroplets merge into a continuous multilayer when they grow to about 3 molecular layers thick. 3) The layer continues to grow until the critical thickness for freezing is reached. 4) The critical ice cluster continues to grow.
Scale selection of mixed Rossby-gravity waves through wave-mean flow interactions
Authors: Mahó Sándor István , Žagar Nedjeljka , Vasylkevych Sergiy
Published: March 2024

Mixed Rossby-gravity (MRG) waves contribute significantly to tropical variability in the upper troposphere and the stratosphere. Studies based on reanalysis data suggest that the scale of MRG waves in the two regions is different, with the troposphere dominated by synoptic-scale MRG waves, while the MRG waves in the stratosphere have planetary scales. Using the recently discovered excitation mechanism of the MRG waves by wave-mean flow interactions, we investigate whether this mechanism can explain the different scale selection in the troposphere and the stratosphere.We carry out high-accuracy numerical simulations with a spherical shallow water model (TIGAR) that includes the MRG wave as a subset of prognostic variables. This framework allows to identify wave-mean flow interactions as the main driver of MRG scale selection in comparison with excitation driven by external forcing and wave-wave interactions. Simulations with idealized background zonal wind field and profiles derived from ERA5 reanalysis from 1 and 200 hPa show that the jet position is a decisive factor for the MRG scale selection. Particularly, when the jet is located closer to the equator, as in boreal winter in the troposphere, synoptic-scale MRG waves are excited. In the case of jets embedded well in extratropics (40-50°), such as in the upper stratosphere, wave-mean flow interactions generate MRG waves with planetary scales. These results explain the MRG scale selection in the upper troposphere and the stratosphere by a single mechanism and highlight the importance of representing accurately wave-mean flow interactions in climate models.
Spatiotemporal Changes in Lake Water Extents in the Lakes Region (Türkiye) and the Role of Climateand Land Cover Parameters
Authors: Sağır Çağdaş , Peker Emin Atabey , Yılmaz Koray Kamil , Süzen Mehmet Lütfi
Published: March 2024

The impacts of global climate change extend to population dynamics, food security, agricultural activities, and water demand, thus presenting complex and urgent challenges associated particularly with the water resources. Türkiye's Lakes Region is situated in the Mediterranean region, which is recognized as a climate change hotspot and further stressed by ever-increasing water demand arising from rapid population growth. Due to the convergence of these factors, the lakes in the Lakes Region face significant challenges with the phenomenon of shrinking lakes.This study examines the spatio-temporal changes in lake waters in Türkiye's Lakes Region, consisting of sixteen lakes. Using Landsat 5, 8, 9, and Sentinel-2 satellite images, the surface area changes were analyzed via NDWI in the Google Earth Engine environment from April 1984 to April 2023. To assess hydrological/hydrogeological conditions accurately, water volume calculations were performed in lakes having in-situ bathymetry and water level measurements. We analyzed MODIS Terra Land Cover dataset and climatic variables such as precipitation, and evaporation-transpiration to understand the degree of anthropogenic and climatic drivers effecting the study lakes.Our results indicated that, for large lakes such as Burdur, Beyşehir and Eğirdir, the period of influence of climatic parameters is close to two years. The effect period varies based on lake bathymetry, size, and hydrodynamic characteristics of the recharge basin. Lake water losses were primarily attributed to climatic factors, with clear links to climatic parameters until 2016. After 2016, a shift of precipitation to the summer season significantly impacted the hydrological system, intensifying the shrinking in the lakes. We conclude that the dominant driver for the shrinking lakes is the climatic effects and the anthropogenic effects for the whole-time interval has been found negligible. Of the lakes considered in this study, only Lake Akşehir should be excluded from this assessment. Lake Akşehir was found to be the only lake where human impact was clearly predominant.
Can we quantify the impact of the modeler on the model?
Authors: De Vos Leon Frederik , Mahajan Karan , Rüther Nils
Published: March 2024

Hydrological and hydraulic models are historically different disciplines and work on different scales.   The recent increase in computational resources allows for the two models to be combined into one model having one holistic approach. This removes the bottleneck of the data linkage between the two disciplines.In this study, we apply the two-dimensional module of the open-source software openTELEMAC-MASCARET with the included SCS-CN method on an ungauged catchment in central Germany with an area of around 58 km². The catchment is part of the Main River tributary. We describe the excessive data preprocessing of the building and land use data, and the topography to sufficiently represent the small-scale stream geometry. This preprocessing is subjective in selecting different thresholds, such as the degree of mesh refinement in the streams and the foreland, or a minimum size for buildings to be represented in the model. Additionally, the SCS-CN method is highly sensitive to the model results, as small changes in the CN-values already significantly alter the total volume of water in the model. We collect the different sources of subjectivity and uncertainty and rank them based on the impact on the model results. The results will lead to a better view of the potential of combined hydrological-hydraulic models.
Developing a replicable and cost-effective solution for monitoring algal concentrations in lake Lugano to facilitate timely decision-making
Authors: Strigaro Daniele , Capelli Camilla , Cannata Massimiliano
Published: March 2024

Monitoring water resources is a key aspect to better understand the effects of human activities, as well as the impacts of climate change, and to appropriately react through adequate mitigation measures. In Switzerland, during the last few summers, Lake Lugano exhibited favorable environmental conditions for the proliferation of algae, primarily due to the high availability of nutrients, which is also linked to the increase in water temperature. In some cases, these algal blooms involve the proliferation of cyanobacteria, which can be dangerous to human health. This phenomenon was particularly significant last summer, leading to the prohibition of lake access for swimming throughout the season in many locations. 

For these reasons, a prototype early warning monitoring system has been implemented and tested using an open approach. Essentially, the system, based on a fluorimeter, collects real-time data and, based on specific thresholds, can send notifications to administrative personnel to monitor water quality status. This allows for timely water sample collection and analysis to monitor the presence of harmful species. The system is built on the same technology developed during the INTERREG project SIMILE, where a monitoring platform was developed and installed in the middle of Lake Lugano. This platform not only monitors algal pigments but also tracks temperature, dissolved oxygen concentration, and pH at different depths. 

This system has shown promising preliminary results, ensuring data continuity and timely notifications. In this presentation, we aim to showcase the technologies used on the server side and the node side, sharing our findings and experiences in developing such a system based as much as possible on open-source components. The system is fully replicable, and during this year, we are planning to further develop it by installing an updated solution in another locations on the lake. In fact, it is gaining interest, especially among the numerous lidos along the lake's shores. Of course, valuable additional work is needed to increase awareness among the population regarding the behavior to adopt when the lake exhibits specific conditions to limit potential health issues.