bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving early-age performance of alkali-activated slag paste backfill with calcium salts at low temperature
Authors: Wang Zhuoran , Gu Xiaozhong , Jiang Haiqiang
Published: March 2024

The hydration of alkali-activated slag (AAS) is highly sensitive to the curing temperature, especially at early ages. In low temperature environment, cemented paste backfill made of AAS (AAS-CPB) exhibits notably reduced early-age uniaxial compressive strength (UCS), attributable to the inhibitory effect of low temperature on slag hydration. This study aims to improve the performance of AAS-CPB at low temperatures by incorporating chemical additives. The results shows that calcium salts, specifically CaCl2, CaSO4, and Ca(COOCH3)2, can increase the early-age UCS of AAS-CPB by up to 1050%, depending on the specific anion involved. Overall, CaCl2 provides the greatest enhancement in the UCS. However, the presence of these salts result in strength degradation at later ages. A pronounced exponential relationship is evident between UCS and ultrasonic pulse velocity. The change of conductivity and moisture content are valuable indicators of hydration process at low temperatures. C(N)-A-S-H, hydrotalcite and portlandite are the primary hydration products. Anions play a decisive role in the morphology, precipitation and quantity of C(N)-A-S-H. The slag hydration degree and UCS basically exhibit a consistent trend. 
The decrease of salinity in lakes on the Tibetan Plateau between 2000 and 2019 based on remote sensing model inversions
Authors: Zhu Liping , Liu Chong , Ju Jianting
Published: March 2024

Salinity is an essential factor of lake water environments and aquatic systems. It is also sensitive to climatic changes and human activities based on concentration variations of solved minerals. However, there are few consecutively temporal studies on lake salinity variations on the Tibetan Plateau because the harsh environmental conditions make it difficult to carry out in-situ observations for several lakes. In this study, we constructed a remote sensing retrieval model for lake salinity based on 87 in-situ lake investigations; moreover, interannual lake salinity and associated variations from 152 lakes larger than 50 km2 were analyzed on the Tibetan Plateau. A significant decreasing trend in lake salinity was observed between 2000 and 2019 (p < 0.01). The spatial variation of lake salinity was negatively correlated with lake area changes, and the optical characteristics of salt mineral solutions were generally positively correlated with mineral concentration based on the absorption coefficients of ionic solutions. The decreasing trend of lake salinity was not directly affected by the precipitation, but was potentially dominated by the expanding lake water volume. This study improves the understanding of regional water environmental changes and management efficacy of water resources.
Why cannot ions form outflow for electron-only reconnection in kinetic turbulence?
Authors: Zhang Meng , Zhou Meng , Yi Yongyuan , Song Liangjin , Pang Ye , Xiao Hui
Published: March 2024

Electron-only magnetic reconnection, in which ions do not couple, has recently been observed in the turbulent magnetosheath and magnetotail and is associated with magnetic flux rope coalescence. This paper reproduces the electron-only reconnection that in turbulent plasma environments via 2.5D particle-in-cell simulations. By statistical analysis and study of individual ion trajectories. We have discovered the reason why Electron-only magnetic reconnection ions cannot form an out flow in turbulence. Due to the weak magnetization effect of ions in turbulence, it is difficult for ions to enter the magnetic reconnection structure from the inflow region (only about 10% in our study). Due to the large cyclotron radius of ions in turbulence compared with the reconnection structure, it is difficult for the reconnected ions to be effectively deflected by the normal magnetic field to form an outflow. The ions are mainly affected by various electric fields generated by magnetic island motion in turbulence. We compared the results with standard magnetic reconnection and performed an energy analysis.
Improving the representation of snow over sea-ice in the SI3 model
Authors: Brivoal Theo , Guemas Virginie , Rousset Clement , Vancoppenolle Martin
Published: March 2024

Snow plays a crucial role in the formation and sustainability of sea ice. Due to its thermal properties, snow acts as an insulating layer, shielding the ice from the air above. This insulation reduces the heat transfer between the sea-ice and the atmosphere. Due to its reflective properties, the snow cover also strongly contributes to albedo over ice-covered region, which gives it a significant role in the Earth's climate system.
Current state-of-art climate models use over-simple representations of the snow cover. The snow cover is often represented with a one-layer scheme, assuming a constant density, no wet or dry metamorphism or assuming that no liquid water is stored in the snow. Here, we present the integration of a more advanced snow scheme (ISBA-ES) into the sea-ice model SI3, which serves as the sea-ice component for upcoming versions of the CNRM climate model (CNRM-CM). We compare 1D simulations over the Arctic using this new scheme with observational data and simulations utilizing the previous SI3 snow scheme. Overall, the snow simulated by the ISBA-ES scheme is realistic. We also present a sensitivity analysis of the snow and sea-ice in the SI3 model, exploring various options in the ISBA-ES scheme. Our findings reveal a strong sensitivity of both the snow and the sea-ice to the representation of liquid water in snow and the parameterization employed for calculating snowfall density.
CAS-ESM2 successfully reproduces historical atmospheric CO2 in a coupled carbon-climate simulation
Authors: Zhu Jiawen , He Juanxiong , Ji Duoying , Li Yangchun , Zhang He , Zhang Minghua , Zeng Xiaodong , Fei Kece , Jin Jiangbo
Published: March 2024

Atmospheric carbon dioxide (CO2) concentration is increasing rapidly since the Industrial Revolution, which has led to unequivocal global warming and crucial environmental change. It is extremely important to investigate interactions among atmospheric CO2, physical climate system and carbon cycle in underlying surface for a better understanding the Earth system. Earth system models are widely used to investigate these interactions by a coupled carbon-climate simulation. The Chinese Academy of Sciences Earth System Model version 2 (CAS-ESM2) has successfully fixed a two-way coupling of atmospheric CO2 with climate and carbon cycle in land and ocean. Using CAS-ESM2, we conducted a coupled carbon-climate simulation by following the CMIP6 proposal of historical emission-driven experiment. This study examines the modeled CO2 by a comparison to observed CO2 in sites Mauna Loa and Barrow, the Greenhouse Gases Observing Satellite (GOSAT) CO2 product. The compared results show that CAS-ESM2 agrees very well with observations in reproducing the increasing trend of annual CO2 during the period 1850−2014 and in capturing the seasonal cycle of CO2 in the two baseline sites, as well as over northern high latitudes. These agreements illustrate a good ability of CAS-ESM2 in simulating carbon-climate interactions, even though uncertainties remain in the processes. This study reports an important stage of the development of CAS-ESM with the carbon and climate coupled, and this coupling will provide significant scientific supports for climate research and China’s goal of carbon neutrality.
Comparison between the gravity wave stress parameterized in a climate model and simulated by the high-resolution non-hydrostatic global model ICON
Authors: Toghraei Iman , Lott François , Köhler Laura , Stephan Claudia , Alexander Joan
Published: March 2024

We compare the parameterization schemes that represent gravity waves in the Atmospheric Component of the IPSL Climate Model (LMDZ6A) and the high-resolution ICOsahedral Nonhydrostatic Weather and Climate Model (ICON). Our focus lies in assessing the capabilities of the gravity wave drag schemes to predict zonal momentum fluxes derived from ICON. The parameterization is run offline using ICON meteorological fields coarse grained to a healpix grid with size representative of an ESM grid (around 100km x 100km). We then examine the temporal mean, horizontal mean, and zonal mean gravity wave stresses predicted by the parameterizations and compare them to the zonal momentum fluxes associated with the ICON subgrid scale fields (e.g. the motions that are filtered out during the coarse-graining). The investigation reveals that in the stratosphere, the parameterizations have some skill at predicting zonal momentum fluxes of ICON, and this without prior tuning. More specifically, the parameterized gravity wave stresses due to mountains, convection and fronts align reasonably well with the zonal momentum fluxes from ICON in the stratosphere, each scheme consistently playing a dominant role where it should (frontal waves dominating in the midlatitude storm tracks, convective waves in the tropics, and mountain waves over orography). This permits physical interpretations of the origin of the gravity waves predicted by ICON, but raises challenges when extending this comparison to the troposphere. There, the agreement between the parameterized stress and the ICON subgrid scale stress is much weaker, which is likely attributable to the fact that in the troposphere subgrid scale forced motions like convective cells produce stresses much larger than the gravity wave stresses.
On-site inspection in monitoring of water flow for the calibration of hydraulic models and the statistical analysis of the hydraulic output. Case study: The river Nileas in North Euboea Greece, before and after the storm Elias in September 2023
Authors: Moraiti Konstantina , Sigourou Stavroula , Kougia Matina , Sargentis G.-Fivos , Koutsoyiannis Demetris
Published: March 2024

North Euboea features elevated topography, expansive wild forests, and numerous small rivers with rainfall patterns similar to the Greek average. Since 2017 a severe disease has affected plane trees (Platanus orientalis), crucial for stabilizing water flow along riverbanks. A devasting wildfire in August 2021 (52,900 hectares burnt areas), further impacted the region significantly. These events induced substantial alterations to the landscape, changing the dynamic of waterflow in watersheds. Our research aims to comprehend, through statistical reasoning, the modifications in water flow and evaluate the collective repercussions on water management. For this purpose, systematic on-site inspections were conducted in April 2023 to map a substream/subriver of the Nileas River and to use water depth for the calibration of the 2D hydraulic model. Also, in September 2023, a devastating storm (“Elias”) caused a dramatic effect in riverbanksdue to the severity of the flood event, and so,in November 2023, we conducted a second systematic on-site inspection to comprehensively assess the situation after the flood event. Hence, a comparative study of Nileas River (before and after the storm) is presented in this study, by emphasizing, through statistical analyses, on the impacts of the landscape changes thoroughlyand to the understanding of the dynamic alterations in the region's watersheds.
Exploring Temperature-Shear Strength Dynamics: A Spatial Modelling Approach for Clay Landslide Susceptibility in Italy
Authors: Loche Marco , Scaringi Gianvito
Published: March 2024

The influence of temperature as a key factor in slope stability, particularly in temperate regions, remains insufficiently explored. This study investigates the thermo-hydro-mechanical (THM) response of expansive soils, focusing on the thermally-induced activity in clay landslides.Establishing a representative thermal variable for broad-scale assessments poses challenges due to material heterogeneities and the intricate nature of THM processes. Our research employs landslide spatial modelling in Italy, concentrating on clay-rich areas with shallow landslides on gentle slopes. Utilizing geo-lithological and geological maps and the Italian National Inventory (IFFI), we apply a Generalized Additive Model (GAM) based on slope units to capture nonlinearities in the temperature-shear strength relationship. A decade-long dataset of Land Surface Temperature (LST) from MODIS, accessible in Google Earth Engine, serves as a key input.The study produces spatial probability maps for clay deposits across Italy, revealing a positive correlation between landslide occurrence and LST on warmer, gentle slopes, especially in Southern Italy. This aligns with the observation that higher temperatures reduce soil and water viscosity, amplifying shear creep rates in clay-rich materials. By elucidating the temperature-slope stability relationship, this study contributes to understanding landslide dynamics in temperate climates, facilitating the development of effective risk recognition strategies.
Fine-scale spatiotemporal characterization of chlorophyll-a in Hong Kong’s coastal waters through the fusion of multisource satellite imagery 
Authors: Jiang Xiaolu , Huang Bo
Published: March 2024

Coastal water quality in Hong Kong faces challenges from nutrient pollution, contaminant discharge, algal blooms, land-derived sedimentation, and climate change effects. To assess water quality in coastal regions, researchers have utilized varying in-situ monitoring data and remote sensing techniques to quantitatively estimate chlorophyll-a concentrations. Despite these efforts, there remains a lack of fine-scale characterization of the spatial and temporal patterns of chlorophyll-a in Hong Kong’s coastal waters, due to the limited resolutions and cloudy covers. Our study seeks to bridge this gap by fusing multisource satellite observations. Existing spatiotemporal image fusion models are primarily designed for land surface reflectance. In this study, we propose using Generative Adversarial Networks (GANs)-based deep learning techniques to improve the fusion of multisource satellite images specifically for watercolor remote sensing. A spatiotemporal fusion deep learning framework based on GANs has been developed to generate daily surface reflectance and temperature at 300 m spatial resolution using data from Sentinel-3 and Himawari-8 satellites. Furthermore, we have devised a random forest-based chlorophyll-a concentration estimation model  that employs the blended high-resolution data derived from multi-source satellite observations and extensive in-situ monitoring data obtained from 76 marine water quality monitoring stations administered by the Hong Kong Environmental Protection Department (HKEPD). These independent in-situ monitoring datasets also serve as valuable resources for evaluating the performance of satellite-derived chlorophyll-a concentrations. Consequently, we conducted a fine-scale mapping of chlorophyll-a distribution in Hong Kong's coastal waters to analyze spatiotemporal characterization of water quality. This approach holds promise for real-time, fine-scale water quality monitoring using high-frequency satellite observations in the future.
Quantitative evaluation of sand body connectivity in shallow water delta front based on extreme learning machine
Authors: Wang Junjie , Zhang Xianguo
Published: March 2024

 In order to better predict the connectivity of sand body in the shallow water delta front, taking the shallow water delta front sand body in the Kong 1st section of the Fenghuadian Oilfield in Huanghua Depression as an example, quantify and optimize the factors that affect the sand body connectivity, and then establish a nonlinear mapping model with the optimized parameters and the connectivity level of sand bodies to quantitatively predict the sand body connectivity by using extreme learning machine, and the predicted results are compared with those of support vector machine to analyze its effectiveness and advantages. Finally, apply the model to the study area to verify its practical application effect. The results show that: 1) Four parameters, including sand-ground ratio, interlayer thickness, interlayer density and permeability, were selected to predict sand body connectivity by using extreme learning machine algorithm, and the accuracy rate reached 92.33%. Extreme learning machine has higher training efficiency than support vector machine algorithm while ensuring prediction accuracy. 2) The extreme learning machine training model was applied to predict the sand body connectivity of ZV2-1 sand layer in the study area, and the dynamic verification coincidence rate is over 92%, which has a good application effect. 3) There are two types of inter-well sand body connectivity modes in the study area: lateral connectivity and internal connectivity. In the lateral connectivity mode, if the two sand bodies are laterally cut and have similar thicknesses, the connectivity is good. In the internal connectivity mode, if the interbeds within the sand body are not developed, the connectivity is good.
Disentangling wave-like atmospheric trends in the northern hemisphere midlatitudes
Authors: van Straaten Chiem , Happé Tamara , D'Andrea Fabio , Coumou Dim
Published: March 2024

Summertime trend analysis reveals that regions in the NH midlatitudes experience a marked set of changes in surface temperature, sea level pressure, and upper-atmosphere streamfunction. Among these changes are deeper Atlantic lows, extreme Western European temperatures, and stronger highs over Western Russia. As these regional signatures tend to lie outside the range of CMIP6 model simulations they might constitute a joined dynamic response that is missed by the models. Here, we examine to what degree the regional signatures cohere as one increasingly prevalent circumglobal wave, or to what degree they reflect distinct regional processes. For this we use both ERA-5 reanalysis data and a selection of CMIP6 climate model simulations. In the process, we try to better understand the mismatch between observations and climate models.
Quantifying Uncertainty in Surrogate-based Bayesian Inference
Authors: Guthke Anneli , Reiser Philipp , Bürkner Paul-Christian
Published: March 2024

Proper sensitivity and uncertainty analysis for complex Earth and environmental systems models may become computationally prohibitive. Surrogate models can be an alternative to enable such analyses: they are cheap-to-run statistical approximations to the simulation results of the original expensive model. Several approaches to surrogate modelling exist, all with their own challenges and uncertainties. It is crucial to correctly propagate the uncertainties related to surrogate modelling to predictions, inference and derived quantities in order to draw the right conclusions from using the surrogate model.While the uncertainty in surrogate model parameters due to limited training data (expensive simulation runs) is often accounted for, what is typically ignored is the approximation error due to the surrogate’s structure (bias in reproducing the original model predictions). Reasons are that such a full uncertainty analysis is computationally costly even for surrogates (or limited to oversimplified analytic cases), and that a comprehensive framework for uncertainty propagation with surrogate models was missing.With this contribution, we propose a fully Bayesian approach to surrogate modelling, uncertainty propagation, parameter inference, and uncertainty validation. We illustrate the utility of our approach with two synthetic case studies of parameter inference and validate our inferred posterior distributions by simulation-based calibration. For Bayesian inference, the correct propagation of surrogate uncertainty is especially relevant, because failing to account for it may lead to biased and/or overconfident parameter estimates and will spoil further interpretation in the physics’ context or application of the expensive simulation model.Consistent and comprehensive uncertainty propagation in surrogate models enables more reliable approximation of expensive simulations and will therefore be useful in various fields of applications, such as surface or subsurface hydrology, fluid dynamics, or soil hydraulics.
Deciphering the Multiscale Association between Indian Precipitation-Arctic Teleconnections Using Wavelet Analysis. 
Authors: kulkarni sujata , Agarwal Ankit
Published: March 2024

The warming of the Arctic region is a significant global concern, and its repercussions extend far beyond polar and mid-latitudes. Rapid changes in sea ice have the potential to significantly impact atmospheric circulation, leading to variations in precipitation patterns across India at different spatial and temporal scales. The present study attempts to characterize the influence of Arctic Sea ice on the monthly precipitation over meteorologically homogeneous regions in India. To consider the regional variability of sea ice, the Arctic region is divided into the Pacific Arctic sector (PAS) and the Atlantic Arctic sector (AAS). The monthly precipitation in India and Arctic Sea ice concentration (SIC) at a monthly scale were decomposed using Maximum overlapping discrete wavelet transform (MODWT). The correlation between precipitation and SIC was analyzed to understand the multiscale association between SIC in the Arctic and precipitation in India. Our results indicate that the Pacific and the Atlantic Arctic sectors exert distinct influences on India. Alterations in sea ice, especially in the Atlantic Arctic sector, profoundly impact Indian precipitation. Notably, the Pacific Arctic sector does not exhibit any influence on the Northeast region across various time scales. The results enhance our nuanced comprehension of the intricate interplays between the climates of India and the Arctic, playing a pivotal role in advancing our ability to predict global climate.
Clouds and precipitation in the initial phase of marine cold air outbreaks as observed by airborne remote sensing
Authors: Schirmacher Imke , Schnitt Sabrina , Klingebiel Marcus , Maherndl Nina , Kirbus Benjamin , Crewell Susanne
Published: March 2024

During Arctic marine cold air outbreaks (MCAOs), cold and dry air flows from the central Arctic southward over the open ocean. There, cloud streets form that transform to cellular convection downstream under extreme surface heat fluxes. MCAOs strongly affect the Arctic water cycle through large-scale air mass transformations and can lead to extreme weather conditions at mid-latitudes. The description of air mass transformations is still challenging partly because previous observations do not resolve fine scales and lack information about cloud microphysical properties. Therefore, we focus on the crucial initial phase of development within the first 170 km over open water of two MCAO events with different strengths observed during the HALO-(AC)3campaign. Both times the POLAR 5 and 6 aircraft flew several legs along the same track perpendicular to the cloud streets crossing the sea ice edge several times to allow a quasi-Lagrangian perspective. Based on high-resolution remote sensing and in-situ measurements, the development of the boundary layer, formation of clouds, onset of precipitation, and riming are studied. We establish a novel approach based on radar reflectivity measurements only to detect roll circulation that forms cloud streets.For the event with the stonger contrast between surface and 850 hPa potential temperature (MCAO index), cloud tops are higher, more liquid-topped clouds exist, the liquid layer at cloud top is wider, and the liquid water path, mean radar reflectivity, amount of rime mass, precipitation rate and occurrence are larger compared to the weaker event. However, the width of the roll circulation is similar for both MCAO events. All parameters, moreover, evolve with distance over open water, as the boundary layer deepens and cloud top heights rise. Cloud streets form after traveling 15 km over open water. After 20 km, cloud cover increases to just below 100 % and after around 30 km, precipitation forms. We find that maxima in the rime mass have the same horizontal scale as the roll circulation. The presentation will highlight how cloud macro- and microphysical parameters vary with distance over open water and explain the differences between both MCAO events.
Observational investigation of Hall effect in asymmetric magnetic reconnection 
Authors: Zhang Yongcun
Published: March 2024

Using MMS observation, we do a series of studies to investigate Hall effect in multiple reconnection cases at dayside magnetopause. The studies show the following interesting results. First, the hexapolar Hall magnetic field was observed in collisionless magnetic reconnection for the first time. And the associated electric field and electron dynamic display the different features from previous study. Second, it was found that the middle polar of hexapolar Hall magnetic field can play the role of guide field. Thus, hexapolar Hall magnetic field can make antiparallel reconnection to bear the features of guide field reconnection. Furthermore, the coexistence of hexapolar Hall magnetic field and magnetic flux rope provides the first evidence that the Hall effect in quasi-antiparallel magnetic reconnection can generate the core field inside a magnetic flux rope. Finally, for three reconnection events at the magnetopause, the quadrupolar Hall magnetic fields in them display their respective properties on the intensity asymmetry and the distributing location. The analyses indicate that the different density asymmetry inside the Hall region, but not the asymptotic density asymmetry, is an exact indicator that explains the different observed Hall patterns. This series of studies offer a new insight into the role of Hall effect in collisionless magnetic reconnection, and how the Hall effect works with the evolution of asymmetry during reconnection. 
Integration of satellite and ground-based analyses in the assessment of Pinus nigra Arnold forest fires
Authors: Niccoli Francesco , Altieri Simona , Kabala Jerzy Piotr , Battipaglia Giovanna
Published: March 2024

The Mediterranean basin is exposed to a growing risk of forest fires due to recent climate changes, which are increasing their frequency and intensity. Forest fires can profoundly alter the ecological functions of Mediterranean forests, affecting hydrological regulation, resource supply, soil stability and biodiversity conservation. They also cause physiological dysfunction and tree mortality, significantly reducing the ability of forests to absorb CO2 and mitigate climate change. The study of fire effects is therefore essential for planning effective post-fire management practices and strategies for future fire regimes. Current technological advances allow the integration of ground surveys with satellite analysis, providing a comprehensive approach to fire studies and accurate assessments of ecological effects and post-fire dynamics.In this context, our research focused on analysing the impacts of a forest fire that occurred in July 2017 in a Pinus nigra Arnold forest on Mt. Cairo in central Italy. We integrated satellite analysis to identify fire-affected areas with forest surveys and tree-ring analysis to assess impacts on tree growth, water use efficiency and post-fire CO2 uptake.Our results highlight the importance of using remote sensing to accurately identify fire-affected areas and accurately plan ground-based activities. While remote sensing is key to providing an overview of fire size and distribution, it is equally important to integrate this data with detailed field surveys. In particular, the use of dendrochronology and stable isotopes in tree rings allowed us to assess post-fire tree growth and changes in water use. Our analyses showed that defoliated trees experienced a significant reduction in growth and change in water use due to severe canopy damage. We also found a significant reduction in the ability of damaged trees to absorb CO2 from the atmosphere, highlighting serious implications for the ecosystem service of carbon sequestration.In conclusion, our study shows that the combination of satellite and ground analysis provides a comprehensive understanding of the effects of forest fires, which can significantly contribute to the recovery and restoration goals of fire-affected areas.
Influence of structural geology on rock slope failure in a paraglacial environment: insights from the Southern Swiss Alps
Authors: De Pedrini Alessandro , Manconi Andrea , Ambrosi Christian , Agliardi Federico , Zangerl Christian
Published: March 2024

The onset and development of large rock slope failures in alpine environments are influenced by a combination of multiple factors, including lithology, inherited structural features on different scales, and the morpho-climatic history of the region. In the Southern Swiss Alps, seven large rock slope failure accumulations can be recognized along the five valleys north of Bellinzona, (Riviera, Leventina and Blenio in Canton Ticino, Calanca and Mesolcina in Canton Graubünden).  The region exposes a predominance of crystalline rocks as orthogneiss and paragneiss with similar mechanical characteristics, an aspect that limits the lithological control on the rock slope failures. In addition, the availability of detailed geochronological documentation of both glacial retreat following the Last Glacial Maximum LGM and the major slope collapses motivated the search for a potential correlation, which, however, has not been found (De Pedrini et al. 2023). For this reason, slope failures in this region are potentially controlled by the peculiar structural setting. In this work, we aim at investigating the impact of structural geology on style of activity and timing of the rock avalanches and deep rockslides of the region. We rely on a catalog of the instabilities (Ambrosi and Czerski, 2016 and De Pedrini et al. 2023) and lineament mapping based on the visual interpretation on 0.5 to 2 m resolution hillshade (swissALTI3D multidirectional Hillshade, Federal Office of Topography swisstopo) and stereo-photogrammetry of aerial strips (Image strips swisstopo, Federal Office of Topography swisstopo). The manual tracing of lineaments is compared with an automatic lineaments tracing performed on surface models of Switzerland in the form of a classified point cloud (swissSURFACE3D, Federal Office of Topography swisstopo). Knowledge on structural lineaments and site-specific field surveys allow us to identify the proper structural setting for each large rock slope failure (already collapsed, active or dormant), and to study structural patterns that may promote slope response after deglaciation at regional scale.The results of this analysis, aimed at the definition of the influence of glacial retreat plus the influence of structural geology, could provide an additional instrument to the comprehension of the paraglacial slope response in crystalline rocks and could thus represent an added value for long-term hazard assessment.
Exploring the Reciprocity Behavior Distributions in Space for Hydrogeological Parameters
Authors: Hsu Zi-Jun , Lin Hong-Ru , Wen Jet-Chau
Published: March 2024

Past studies of hydrogeological parameters of aquifers have not using drawdown data from multiple sets of sequential pumping tests (SPT) at the same site to characterize the interaction of hydrogeological parameters (such as transmittance, T and storage coefficient, S) distribution field. Therefore, the purpose of this study was to use the same site (well site at the northeast corner of Yunlin University of Science and Technology, Douliu City, Yunlin County) collected for many years (20xx，20xx..year, five groups in total) of SPT drawdown data. First, the interaction between the drawdown water levels from the same observation well and five sets of pumping tests was analyzed. Afterwards, this study used the numerical method of (hydraulic tomography, HT) to analyze the leakage data of five groups of SPTs., reverse calculation the distribution of T and S of five groups of SPT and a spatial comparison was performed, comparing the interaction between 5 sets of T and S distribution fields, discuss in different time and space background, interaction of distribution field of local hydrogeological parameters.
Different responses of cereals to interacting climatic indicators in Northern Europe.
Authors: Tootoonchi Faranak , Vico Giulia
Published: March 2024

Precipitation and temperature interactively impact crop yields. Climate change is expected to be detrimental in most regions because of excessive temperatures and reduced water availability for crops. Nevertheless, at higher latitudes, warming might be an opportunity, unless excessive or co-occurring with other damaging conditions. To effectively evaluate the prospects of future staple crop production in Nordic conditions, we need to examine the past response of cereals to climatic indicators, not only averaged over the growing season but also at different physiologically relevant developmental stages. Moreover, we need to consider the legacy impacts of conditions during pre-growing period. Using county-level staple crop yield and meteorological data for 1965-2020 across Sweden, we systematically explored the role of various climate indicators on cereal yields (winter and spring wheat, spring barley and oats) in a Northern Europe context. For all crops, precipitation and average temperature over the entire growing season were the most relevant to explain yields. Combinations of higher precipitation totals and average temperature increased the yield for winter wheat. The same combination, as well as combinations of lower precipitation and lower average temperature, increased yield for spring barley. Increasing length of the longest dry period up to 3 weeks, combined with intermediate temperatures, increased yield for spring wheat and oats. Crops also responded to combinations of precipitation and temperature indicators during the post-flowering period for winter wheat and oats, and pre-flowering for spring barley, placing models with indicators in these periods as the second best models, based on the Akaike Information Criterion. For spring wheat, aridity index, i.e., a proxy of water availability prior to sowing, ranked as the second best explanatory indicator. Considering current future projections, both precipitation totals and temperature averages are likely to increase in Sweden. These changes in climatic conditions can lead to increasing opportunities for cultivation of spring crops such as oats with high resilience toward water logging, or promote a shift from spring sown-crops to autumn-sown crops such as winter wheat with more resilience toward unfavorable climatic conditions, even beyond currently cultivated latitudes.
Elemental fluxes into 3.0-billion-year-old marine environments: evidence from trace elements and Nd isotopes in banded iron formations from the Murchison Greenstone Belt, South Africa
Authors: Krayer Johanna , Viehmann Sebastian , Mayer Alina , Schulz Toni , Koeberl Christian , Hofmann Axel , Jodder Jaganmoy , Willbold Matthias , Weyer Stefan
Published: March 2024

Banded Iron Formations (BIFs) are authigenic, marine sediments directly reflecting the chemical composition of ancient seawater. BIFs serve as prime geochemical archives for the reconstruction of Precambrian marine environments. However, due to the scarcity of well preserved Archean rocks, atmospheric and hydrospheric environmental conditions within this time frame are still incompletely understood. In particular, elemental fluxes derived from continental weathering and submarine hydrothermal fluxes that affected ancient seawater chemistry are cornerstones for our understanding of the evolution of marine habitats through time. Here we present major- and trace element concentrations in combination with Nd isotopic compositions of 13 samples of Mesoarchean Algoma-type greenschist-facies BIFs from the ca 3.0 Ga old Murchison Greenstone Belt, South Africa. Individual Fe- and Si-rich layers are monitored for sample purity based on their chemical composition. Neodymium isotope compositions, in combination with trace element contents of BIF samples with varying amounts of clastic detritus, are further used to reconstruct the Murchison depositional environment and identify the origin of dissolved and detrital components entering the ancient ocean around 3.0 Ga ago.Eight samples with low immobile element concentrations display typical shale-normalized Archean seawater-like rare earth and yttrium (REYSN) patterns with positive LaSN, EuCN, and GdSN anomalies, super-chondritic Y/Ho ratios, and an enrichment of heavy REYSN over light REYSN, implying an open marine-dominated depositional setting with contributions from submarine high-temperature, hydrothermal systems. A Sm-Nd regression line yields an age of 2.98 ± 0.19 Ga that overlaps with the proposed depositional age, suggesting negligible post-depositional alteration on the REY composition of the pure BIF layers. In contrast, higher concentrations of immobile elements (e.g., Zr) and/or non-seawater-like REYSN patterns are characteristic for the remaining five BIF samples, indicating elevated detrital input or post-depositional alteration. A regression line of the impure BIF layers yields an age of 2.49 ± 0.15 Ga, reflecting a potential post-depositional overprinting event such as the 2.6 Ga old Limpopo orogeny. The Nd isotopic compositions of pure and impure BIF samples cover a wide range of ca. two epsilon units suggesting a mixture of weathered mafic and felsic sources for the dissolved and suspended fluxes into the Murchison ocean.
AMOC tipping under Climate Change in the Community Earth System Model
Authors: van Westen René , Dijkstra Henk
Published: March 2024

Recent quasi-equilibrium simulations with the Community Earth System Model (CESM) have shown that the Atlantic Meridional Overturning Circulation (AMOC) in a pre-industrial climate is a multi-stable system (van Westen & Dijkstra, 2023). By slowly increasing the surface freshwater forcing strength over the North Atlantic Ocean, the AMOC tips from a northward overturning state (strength of 17 Sv) to a fully  collapsed state (strength of 0 Sv). When reversing the freshwater forcing, the AMOC recovers at  smaller values of this forcing compared to the collapse, giving rise to hysteresis behaviour. Here we analyse AMOC tipping under climate change using the same CESM version. From the hysteresis experiment, we branch off simulations under fixed freshwater forcing values to find the statistical steady states. We follow these states under climate change up to 2100 (historical forcing followed by SSP5-8.5) and then run the simulation into equilibrium under constant year 2100 conditions. We find an AMOC tipping event during the 21st century and we compare this event to the one from the pre-industrial quasi-equilibrium simulation. The rate of AMOC changes and the AMOC-related impacts are comparable to the quasi-equilibrium simulation. However, the initial AMOC weakening and the collapsed AMOC state are very different under climate change. Temperature changes primarily drive the initial AMOC weakening and the collapsed state has a very weak (strength of 1 Sv) and shallow (< 1000 m) northward overturning circulation in the Atlantic Ocean. The results indicate that the strong northward overturning statistical steady states disappear under climate change and that only the collapsed AMOC state exists under a high-end emission scenario.
Reconciling ocean mass changes from 20 years of GRACE and GRACE Follow On observations
Authors: Ludwigsen Carsten Bjerre , Andersen Ole Baltazar , Watson Christopher , King Matt
Published: March 2024

The total mass change of the Earth's land surface precisely offsets the combined changes in the atmosphere and oceans, resulting in a net-zero change for the entire system (land+ocean+atmosphere).Closing the ocean mass budget is crucial for understanding current and future sea-level changes. Recent efforts to reconcile ocean mass observations from GRACE and GRACE-Follow On satellites (hereafter unitedly referred to as ‘GRACE’) with both steric-corrected altimetry and and land/ice to ocean estimates have revealed a discrepancy in the mass budget (Wang et al, 2022; Barnoud et al, 2022). This finding indicates a concerning misalignment in our global observation system or understanding of earth mass transport.This study uses GRACE-independent estimates/models of land surface mass changes to validate 20 years of GRACE observations. By calculating the monthly Gravitational, Rotational, and Deformational (GRD) response to 20 years of land mass changes, we reconstruct the global, regional, and seasonal ocean mass changes observed by GRACE from 2003 to 2022.Over the 20-year period, the ocean mass reconstruction aligns well with the GRACE observations. However, a significant deviation emerges after 2020, with the reconstruction showing a larger ocean mass change than GRACE. We demonstrate that this deviation is likely caused by an underestimation of Western Africa precipitation in the ERA5 reanalysis, commonly used by hydrological models to estimate changes in land water storage. Land mass observations from GRACE further confirmvthis underestimation and shows great alignment between models and observations when excluding sub-Saharan Africa.Our results show a global agreement between GRACE and GRD-induced ocean mass changes, suggesting that the misalignment between GRACE and steric-corrected altimetry is likely due to errors in the ARGO observing system. A reported 'salinity-drift' is the primary source of error, and together with an error in the wet path delay originating from drift in the radiometer of the Jason-3 satellite explains most of the post-2016 difference between GRACE and steric-corrected altimetry is identified. The remaining differences likely originate from GIA and/or Argo-biases.
Exploring the Hidden Exchanges: Groundwater-Surface Water Interactions in a Critical Zone Observatory
Authors: Klaus Julian , Blöschl Günter , Bonanno Enrico , Glaser Barbara , Gourdol Laurent , Hissler Christophe , Hopp Luisa , Pfister Laurent , Smettem Keith
Published: March 2024

The exchange between groundwater (GW) and surface water (SW) plays a crucial role for streamflow generation and the biogeochemical cycles within landscapes. However, accurately observing and predicting this exchange remains challenging due to the spatial heterogeneity and temporally dynamic fluxes of groundwater within the stream corridor. This presentation offers new insights into the characteristics of GW-SW interactions and hydrological processes within the hillslope-riparian-stream continuum, employing a combined experimental and modeling approach. The research builds on a comprehensive, long-term dataset obtained through baseline monitoring in the Weierbach Experimental Catchment (WEC) in Luxembourg that is a 45-hectare forested catchment. In addition to baseline monitoring, our approach involved (i) a network of 43 wells and piezometers along a selected stream reach for continuous monitoring and tracer experiments, (ii) a network of 13 wells along the riparian-hillslope interface, and (iii) ground-based thermal infrared imagery to observe spatiotemporal dynamics of surface saturation along the stream corridor. An integrated surface-subsurface hydrologic model served as a hypothesis-testing tool to examine whether surface saturation is predominantly driven by groundwater inflow or precipitation and how the relevance of the processes – surface ponding from precipitation or subsurface exfiltration – change in space and time.We coupled the hydrological model with a hydraulic mixing-cell approach that enabled deciphering the contributions from different water sources to SW. The well network and associated artificial tracer experiments provided valuable insights into the direction of GW-SW exchange, revealing directional variability at scales of a few meters. Additionally, wells at the riparian-hillslope interface demonstrated a strong non-linearity of GW contributions to SW, influenced by GW table fluctuations. The observed and simulated surface saturation aligned well, suggesting that GW exfiltration primarily controls surface saturation in the stream corridor. Furthermore, the mixing-cell simulations revealed that subsurface water exfiltration is the dominant source for riparian surface water and intermittent streamflow, with distinct differences between stream water and riparian surface saturation. Overall, the combination of experimental techniques, hydrologic modeling, and well networks clearly improved our understanding of GW-SW interactions and revealed previously hidden exchanges in the WEC.
Diurnal Variability of Global Precipitation: Insights from Hourly Satellite and Reanalysis Datasets
Authors: Pradhan Rajani Kumar , Markonis Yannis , Marra Francesco
Published: March 2024

Accurate estimation of precipitation at the global scale is of utmost importance. Even though satellite and reanalysis products are capable of providing high spatial-temporal resolution estimations at the global level, their uncertainties vary with regional characteristics, scales, and so on. The uncertainties among the estimates, in general, are much higher at the sub-daily scale compared to daily, monthly and annual scales. Therefore, quantifying these sub-daily estimations is of specific importance. In this context, this study seeks to explore the diurnal cycle of precipitation using all the currently available space-borne and reanalysis-based precipitation products with at least hourly resolution (IMERG, GSMaP, CMORPH, PERSIANN, ERA5) at the quasi-global scale (60◦N - 60◦S). The diurnal variability of precipitation is estimated using three parameters, namely, the precipitation amount, frequency, and intensity, all remapped at a common resolution of 0.25◦ and 1 h. All the estimates well represent the spatio-temporal variation across the globe. Nevertheless, considerable uncertainties exist in the estimates regarding the peak precipitation hour, as well as the diurnal mean precipitation amount, frequency, and intensity. In terms of diurnal mean precipitation, PERSIANN shows the lowest estimates compared to the other datasets, with the largest difference observed over the ocean rather than over land. As for diurnal frequency, ERA5 exhibits the highest disparity among the estimates, with a frequency twice as high as that of the other estimates. Furthermore, as expected being based on model reanalysis, ERA5 shows an early diurnal peak and the highest variability compared to the other datasets. Moreover, among the satellite estimates, IMERG, GSMaP, and CMORPH exhibit a similar pattern with a late afternoon peak over land and an early morning peak over the ocean.