bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysing geodetic fixed point survey time series to evaluate the long-term activity of DSGSDs in Austria
Authors: Ostermann Marc , Blauensteiner Franz
Published: March 2024

A fixed point in geodesy is a stable survey point that fulfils the following two conditions: The point is known in coordinates from a previous survey (by position and/or height) and the point is permanently marketed (stabilised) in nature. Fixed points serve as reference points for surveys of all kinds. To determine the coordinates of the fixed points in the modern European reference system ETRS89, not only all previously measured GNSS vectors are used, but also all terrestrial observations measured since 1906, i.e. direction, elevation angle and distance measurements (Otter et al., 2017). More than 20.000 individual RTK measurements on these fixed points by using APOS (Austrian Positioning Service) complete the measurement dataset. Approximately 60.000 triangulation points (TPs) form a three-dimensional point network throughout Austria, whereas about 70 % of all TPs have multiple measurements. Fixed points should be stable, but this is not always the case, as fixed points are often influenced in their spatial position by gravitational mass movements, among other factors.We have interpreted the entire elevation model/hill shade of Austria (1-metre resolution, based on ALS-data) and mapped all DSGSDs that manifest themselves geomorphologically in the terrain. This data set was intersected with the fixed points in order to identify those points that lie within a DSGSD. By analysing the results of the individual fixed point survey epochs, conclusions can be drawn about deformation rates of mass movements after excluding possible sources of error and statements can be made retrospectively up to the year in which the particular point was created (Otter et al., 2017).Overall the fixed point measurements of the Federal Office of Metrology and Surveying Austria (BEV) represent a high quality and long term dataset that stands for its own and can support other slope monitoring methods. The interpretation of the dataset concerning slope deformations is not trivial but can deliver information of the range of movements over decades with uncertainties of 0 to 1.5 cm.By combining different data sources (InSAR, ALS, in-situ measurements, fixed points, ...) we can present a preliminary, comprehensive data set on the activity status and often associated deformation rates of DSGSDs in Austria.References:Otter, J.; Imrek, E.; Melzner, S. (2017) Geodätische Grundlagenvermessung als Werkzeug in der Naturgefahrenanalyse in: Wimmer-Frey, I.; Römer, A.; Janda, C. [Hrsg.] Angewandte Geowissenschaften an der GBA. Wien, S. 147–152.  
Revisiting the physical processes controlling the tropical atmospheric circulation changes during the Mid-Piacenzian Warm Period
Authors: Zhang Ke , Sun Yong , Zhang Xu ,   Team of co-authors of this work
Published: March 2024

The Mid-Piacenzian Warm Period (MPWP; 3.0-3.3Ma), a warm geological period about three million years ago, has been deemed as a good past analog for understanding the current and future climate change. Based on 12 climate model outputs from Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), we investigate tropical atmospheric circulation (TAC) changes under the warm MPWP and associated underlying mechanisms by diagnosing both atmospheric static stability and diabatic processes. Our findings underscore the advantage of analyzing atmospheric diabatic processes in elucidating seasonal variations of TAC compared to static stability assessments. Specifically, by diagnosing alterations in diabatic processes, we achieve a quantitative understanding and explanation the following TAC changes (incl. strength and edge) during the MPWP: the weakened (annual, DJF, JJA) Northern Hemisphere and (DJF) Southern Hemisphere Hadley circulation (HC), reduced (annual, DJF) Pacific Walker circulation (PWC) and enhanced (annual, JJA) Southern Hemisphere HC and (JJA) PWC, and westward shifted (annual, DJF, JJA) PWC. We further addressed that the increasing bulk subtropical static stability and/or decreasing vertical shear of subtropical zonal wind - two crucial control factors for changes in subtropical baroclinicity - may promote HC widening, and vice versa.  Consequently, our study of spatial diabatic heating and cooling, corresponding to upward and downward motions within the TAC, respectively, provides a new perspective for understanding the processes controlling seasonal TAC changes in response to surface warming.
Are near-Coastal Sea Levels Accelerating Faster than Global during the Satellite Altimetry Era?
Authors: Jevrejeva Svetlana , Qu Ying , Palanisamy Hindumathi
Published: March 2024

In our study, we analyze the near-coastal sea level acceleration compared with global values during satellite altimetry (1993–2020) and discuss the potential drivers of regional sea level acceleration. We estimate regional sea level acceleration using high-resolution satellite altimetry sea surface height anomalies. Our study reveals a wide range of regional acceleration estimates, varying from −1.2 to 1.2 mm·yr−2, which can be up to 20 times larger or smaller than the global mean sea level acceleration of 0.07 mm·yr−2. Notably, sea level acceleration near the global coastline is calculated at 0.10 ± 0.03 mm·yr−2, exceeding the global mean sea level acceleration by 40%. Regional patterns of sea level acceleration are in good agreement with acceleration patterns calculated from the steric sea level. However, the magnitude of acceleration is only partially explained by the changes in steric sea level, with increasing contributions from the non-steric component.
Impact and risk assessments in coastal areas are informed by current and future sea level rise and acceleration, which demands a better understanding of drivers for regional sea level acceleration.
 
Spatiotemporal analysis of the background seismicity in Northern Algeria
Authors: Varini Elisa , Benali Amel , Jalilian Abdollah , Idrissou Sara , Peresan Antonella
Published: March 2024

This work has a twofold objective: to analyze for the first time the background seismicity of Northern Algeria and its vicinity and to apply a variety of statistical methods to identify its spatiotemporal features (Benali et al., Axioms, 2023).The earthquake catalog of Northern Algeria and its vicinity includes events from 1950 to 2021 within the region between latitudes 32° and 38° and longitudes -2° and 10°. Based on the investigation of the frequency-magnitude for the overall catalog, the magnitude threshold for completeness is set at 3.7, so that the analyzed dataset includes 1561 earthquakes. The considered area comprises the largest and the most damaging earthquakes ever recorded in the Mediterranean region: the M7.3 earthquake at El Asnam in 1980, the M6.9 earthquake at Boumerdes in 2003, and the M6.7 earthquake at El Asnam in 1954.The dataset is declustered by applying different methods, namely: the Gardner and Knopoff, Gruenthal, Uhrhammer, Reasenberg, Nearest Neighbour, and Stochastic Declustering methods. Each method identifies a different declustered catalog, that is a different subset of the earthquake catalog that represents the background seismicity, which is usually expected to be a realisation of a homogeneous Poisson process over time. A variety of statistical methods is applied to assess whether the background seismicity identified by each declustering method has the spatiotemporal properties typical of such a Poisson process. The main statistical tools of the analysis are the coefficient of variation, the Allan factor, the Markov-modulated Poisson process (also named switched Poisson process with multiple states), the Morisita index, and the L-function.Summing up our findings, all declustering methods reduce the time of correlation structures in the background seismicity at small timescales, but temporal correlation still remains at intermediate and higher timescale ranges. In particular, Gruenthal and Stochastic Declustering methods turn out the most effective in removing the time clustering structures from this catalog. The spatial clustering structure is also significantly reduced, but it is not eliminated from the declustered catalogs, due to the natural clustering of seismicity along active fault systems.
Spatial variation of tropical cyclone rainfall trends in Mainland Southeast Asia
Authors: Chen Aifang , Lu Haiyan
Published: March 2024

Tropical cyclones (TCs) and the associated rainfall (TCR) have received increasing attention because of their catastrophic damages. Due to the differences in TC characteristics and TCR in different ocean basins, the changes in TCR would be complicated for areas receiving TC landfalling from multi-basins. Therefore, separating TCR and TC characteristics from the formation basins can offer more insights for accurately evaluating TCR in the landfalling areas. Here, we selected the TC-prone Mainland Southeast Asia (MSEA) to investigate changes in TCR regarding TC characteristics from the surrounding formation basins from 1983 to 2020. Results show that the interannual variability of the total TCs influencingMSEA (MSEA-ALL-TC) characteristics, including number, total duration, maximum intensity, and accumulated cyclone energy, was dominated by the TCs originating from the Western North Pacific (WNP-TC). However, the total TCR was controlled by the TCs originating from the WNP and the South China Sea (SCS-TC), whose influence on TCR was concentrated in the eastern MSEA. TCR associated with TCs originating from the Bay of Bengal was relatively small and concentrated in the western MSEA. For the whole MSEA, the total TCR contributed up to 47% of the annual extreme rainfall amount. Annual TCR presented significant decreasing trends in the southeast MSEA while increasing trends exist in the northeast. These contrasting trends are attributed to the reduced tendency of WNP-TC track density and the increased SCS-TC rainfall rate. The spatial pattern of the TC track changes is associated with the poleward migration of TC tracks in the WNP. We also found that the SCS-TC induced a higher rainfall rate than the other two basins. The TC characteristics of number, total duration, maximum intensity, and accumulated cyclone energy were significantly correlated with TCR in each formation basin, with the highest correlation of the total duration. This study improves our understanding of the influence of changes in TC characteristics on TCR in the TC multi-source region.
Impacts of urban development on the local weather: A comprehensive analysis from 1970 to 2020 in Madrid.
Authors: Carbone Juan , Sánchez Beatriz , Román-Cascón Carlos , Martilli Alberto , Royé Dominic , Yagüe Carlos
Published: March 2024

The proportion of the world’s population living in cities has increased from 37% to 56% over the last 50 years, and it is expected to continue rising further to 60% by 2030 (UN, 2022). As an essential effect of this evolution, urban land cover has expanded rapidly. In the case of Madrid, the increase in urban fraction during the period from 1970 to 2020 has been 20%. It is well known that urbanization reduces the vegetated cover and modifies surfaces properties altering the surface-atmosphere interactions and the different terms of the Surface Energy Balnace (SEB) compared to nearby rural areas. Therefore, analyzing the influence of these changes in urban land cover contributes to understand the potential risks that urban residents might face considering the urban grown and the expected temperatures increases, as this has adverse impacts on human health, livelihoods, and key urban infrastructure.The aim of the present study is to examine the consequence of Madrid's urban growth on the near-surface air temperature and on the SEB. We conduct a modeling study using WRF-ARW with the multilayer urban parameterization BEP-BEM, in which the land use and the land cover have been modified according to urban expansion in Madrid and its surroundings from 1970 to 2020. Two scenarios of common meteorological conditions of special interest are selected for this study: a period of intense heatwave during the summer season and a short period of strongly stable atmospheric conditions in winter, both observed in 2020. The results show that in areas where the urban fraction become greater an increase in near-surface air temperature is found for both simulated periods, especially during the night, pointing out that the cooling rate decreases in urban areas. The growing of urban land cover over time also modifies the SEB and turbulent transport in Madrid and surroundings, leading to an increase in temperatures, specially for the minima ones.
Wind and wave co-location in the Celtic Sea, UK
Authors: Neill Simon
Published: March 2024

Within the UK, wave power is generally only considered viable along the energetic west coast of Scotland. However, this region has minimal electricity infrastructure, and so it would be challenging to distribute the electricity. One way to further advance wave energy in the UK could be to co-locate less energetic waves sites with offshore wind. This study examines wave power within the Irish Sea, the southern part of which is exposed to the Atlantic Ocean. The spectral wave model SWAN is run for a decade (2012-2021) to quantify the wave energy resource. The high resolution Irish Sea model is nested within an outer model of the North Atlantic, with both models forced by ERA5 wind fields. Monthly mean wave power in the southern part of the Irish Sea (the Celtic Sea) exceeds 30 kW/m during winter months. To investigate the potential for co-location, wave and wind power were compared at a leased floating wind site in the Celtic Sea. Over the simulated decade, r2 ~ 0.5, demonstrating modest potential for co-location of wind and wave energy technologies – considerably less favourable than other sites in the North Atlantic (for example the Canary Islands or the west coast of Scotland) that exhibit greater swell.
Seasonal variation of land subsidence caused by the groundwater abstraction for snow removal in Nagaoka city , Japan
Authors: Yang Yulu , Aichi Masaatsu
Published: March 2024

 This research primarily focuses on predicting and analyzing land subsidence and groundwater level caused by the groundwater abstraction for snow melting during winters in Nagaoka City in Niigata Prefecture , Japan. In this area, significant inconvenience caused by heavy snowfall during winters has led to the adoption of groundwater extraction for snow melting purposes. This countermeasure results in seasonal fluctuations in groundwater levels, contributing to plastic compaction occurrences during winter seasons every year. The uncertainty in modeling land subsidence due to the inability to accurately determine the distribution of subsurface physical property values poses a challenge. Additionally, inadequate data regarding the amount of water extracted for snow melting further complicates the analysis.Combining groundwater level data obtained through Kriging interpolation, we utilized numerical simulations by MODFLOW with subsidence package (IBS) and adjusted model parameters to reproduce the scenarios in this region. The model was calibrated to reproduce groundwater level and subsidence data. By referencing parameters in the existing literatures parameters and experimenting with various scenarios, the model successfully simulated changes in groundwater levels and land subsidence, demonstrating the effectiveness of the model. Moreover, by assigning different permeability coefficients in possible ranges, we determined the maximum extent of snowmelt water's contribution to groundwater replenishment. Through the analysis of various extraction and replenishment schemes, we clarified the main causes of land subsidence and the primary sources contributing to groundwater recovery. We also proposed possible extraction strategies to address the challenge of groundwater extraction under acceptable land subsidence considering the increasing demand for groundwater due to urbanization and possible climate change.
High enrichment of U, Cr, As and V in fish scales from the Namibian shelf of the Benguela Upwelling System.
Authors: Gäng Frederik , Göller Lena , Brüchert Volker , Lahajnar Niko , Pahnke Katharina , Böning Philipp
Published: March 2024

Enrichment patterns of redox- and biosensitive trace elements (TEs) are powerful tools to reconstruct depositional conditions during sedimentation in continental marine sediments. For several TEs (e.g., U, Cr, As and V), the mechanisms that lead to their accumulation in the sediment are not fully understood yet. To complement the discussion, we analyzed several major elements and TEs (P, Ca, Sr, U, V, As and Cr) in fish scales from two short cores (30 cm sediment depth) from the central and southern shelf of the Namibian anoxic-euxinic continental margin (from 67 and 100 m water depth). We found both fresh, young scales in the upper sediments and clearly altered scales, in deeper sections of the cores. The P, Ca and Sr values appear to be good indicators of the changing condition of the respective fish scales, as Ca, Sr and P decrease with the sediment depth from which the fish scales were taken. The lower the Ca, Sr and P values, the more altered the fish scales and the higher the TE enrichment. These more altered fish scales have high values of U (up to 88 ppm), Cr (up to 97 ppm) and V (up to 130 ppm), raising the importance of fish scales as a sink for these elements in shelf sediments, leading to extreme enrichments that are not primarily related to redox conditions. In contrast to the high TE values in altered scales, high values of As (up to 140 ppm) were found in fresh fish scales in core top sections and a decrease with sediment depth. Previous studies showed that high bulk U content in central Namibian shelf sediments is due to high anthropogenic U input by mining activities (in addition to U enrichment during authigenic apatite formation in the sediments). This U-mining activity in the central Namibian hinterland is further reflected in higher U values in the core from the central shelf compared to the core from the southern shelf. The increase of all TEs in scales with increasing sediment depth indicates authigenic enrichment over time within the sediment. Therefore, we suggest that fish scales are an important authigenic sink of several TEs which may be substantial for the element budget calculations in continental margins.
From snow to socio-hydrology: mechanisms behind the 2022 drought in the Alps
Authors: Avanzi Francesco , Munerol Francesca , Milelli Massimo , Gabellani Simone , Massari Christian , Girotto Manuela , Cremonese Edoardo , Galvagno Marta , Bruno Giulia , Morra di Cella Umberto , Rossi Lauro , Altamura Marco , Ferraris Luca
Published: March 2024

Our study delves into the intricate relationship between the 2021-2022 snow deficit in the Italian Alps and subsequent socio-hydrologic repercussions during the ensuing summer drought across the Po river basin, thus elucidating socio-hydrologic response from headwaters to lowlands in an era of change. Starting from early 2022, a high-pressure ridge led to a -88% anomaly in peak Snow Water Equivalent (SWE), which was compounded by episodes of intraseasonal snowmelt and earlier melt-out dates. As a result of this low SWE, a further -10% in summer precipitation, and +1.9°C summer temperature anomaly, terrestrial water storage measured through GRACE hit its all-time low. Meanwhile, we observed an intensification of both anomalies in SWE and in streamflow compared to other recent droughts. Municipal emergency water-use restrictions were issued in correspondence to the peak in snowmelt deficit, rather than the peak in precipitation deficit, with a spatial signature that clearly points to missed snowmelt as a key contributing factor in the escalation of this emergency. This archetypal event, along with the multi-decadal decline in terrestrial water storage, highlights the contributing role of snowmelt deficit in driving socio-hydrologic impacts of droughts in Alpine regions in the context of a warming climate. 
Surface Ocean Cooling in the Eocene North Atlantic Coincides With Declining Atmospheric CO2
Authors: Inglis Gordon , Bhatia Rehemat , Evans David , Zhu Jiang , Muller Wolfgang , Mattey David , Thornalley David , Stockey Richard , Wade Bridget
Published: March 2024

The Eocene (56–34 million years ago) is characterized by declining sea surface temperatures (SSTs) in the low latitudes (∼4°C) and high southern latitudes (∼8–11°C), in accord with decreasing CO2 estimates. However, in the mid-to-high northern latitudes there is no evidence for surface water cooling, suggesting thermal decoupling between northern and southern hemispheres and additional non-CO2 controls. To explore this further, we present a multi-proxy (Mg/Ca, δ18O, TEX86) SST record from Bass River in the western North Atlantic. Our compiled multi-proxy SST record confirms a net decline in SSTs (∼4°C) between the early Eocene Climatic Optimum (53.3–49.1 Ma) and mid-Eocene (∼44–41 Ma). However, from the mid-Eocene onwards, east-west North Atlantic temperature gradients exhibit different trends. This is attributed to inception of Northern Component Water during the early-middle Eocene transition and incursion of warmer waters into the eastern North Atlantic, but additional data sets are required to test this further. We also demonstrate that the onset of long-term Eocene cooling in the western North Atlantic (∼49–48 Ma) occurs synchronously in other ocean basins (e.g., N. Atlantic vs. SW Pacific) and across different latitudinal bands, implying that CO2 was likely responsible for the onset of long-term Eocene cooling.
Energy Transfer between Mesoscale Eddies and Near-inertial Waves from Surface Drifter Observations
Authors: Chen Zhiwu
Published: March 2024

Hourly satellite-tracked surface drifter data are utilized to study energy transfer from eddies to Near-Inertial Waves (NIWs). Spatial velocity gradients are computed from two consecutive velocity estimates derived from the same drifter, providing variable spatial resolutions of (1 km). The eddy-to-NIW energy transfer can be positive or negative, with the positive transfer (forward energy cascade) dominant. The global integrated energy transfer rate (ε) is 0.025 TW, with the anticyclonic eddy contribution dominant over the cyclonic eddy contribution. Given that the global near-inertial wind work (W) is 0.2 TW, the eddy-to-NIW energy transfer efficiency (ε/W) is about 13%, which is one order of magnitude larger than that in low resolution simulations. This result may still underestimate the Eulerian energy transfer by a factor of 2. To our knowledge, this is the first time that this energy transfer is calculated from global drifter observations, providing a baseline for comparison in future studies.
Stochastic Modeling of SLR Observations and its Impact on the Parameter Estimation
Authors: Geisser Linda , Meyer Ulrich , Arnold Daniel , Jäggi Adrian
Published: March 2024

Satellite Laser Ranging (SLR) observations are provided by a global station network of the International Laser Ranging Service (ILRS). Since almost all SLR stations are unique in terms of utilized equipment, e.g., laser system, photo-detector or timing devices, their measurement performances may slightly differ. Furthermore, the tracked satellites have various properties, e.g., material composition (number and type of retro-reflectors or mantel material), diameter, area-to-mass ratio, altitude or inclination, which have an impact on the measurement precision and the requirements on the background force modeling. A reliable estimation of geodetic parameters solely based on SLR can only be performed by combining SLR observations to several spherical satellites provided by the entire ILRS network. To take the quality of each individual SLR measurement into account, several stochastic models, e.g., static or time-variable station- and/or satellitespecific weights, are introduced and their impact on the parameter estimation is studied.
Uncertainty based amplification factors benchmarked by large ensembles of inundation simulations
Authors: Løvholt Finn , Briseid Storrøsten Erlend , Glimsdal Sylfest , Norderhaug Drøsdal Ida , Gibbons Steven J. , Magni Valentina , Romano Fabrizio , Lorito Stefano , Volpe Manuela , Brizuela Beatriz
Published: March 2024

Tsunami maximum inundation heights (MIH) are normally estimated by modelling the hydrodynamics of the overland flow over a limited area using high resolution long wave models. However, in situations where there one need to simulate inundation over large areas, we demand methods that are less resource intensive. The method of amplification factors represents one such simplified and resource efficient method. It is based on precomputed factors using linear shallow water models modelled over bathymetric transects to estimate the ratio of the offshore maximum surface elevation to that at the shoreline. It has been shown previously that we can get a relatively good estimate of the median value of the MIH at given coastline location using amplification factors. Yet, as this method is associated with considerably higher epistemic uncertainty than e.g. solving the nonlinear shallow water equations (due to the additional simplifications), there is need to include a measure of its uncertainty and bias. The main sources of uncertainty include among others the misfit of the method (towards data or more accurate methods) and local spatial variability of the inundation. Here, we present results from recent advancements of the amplification factor method emphasising a much more elaborate uncertainty analysis than employed previously. To this end, we use a unique set of synthetic data from several hundreds of thousands of massive scale nonlinear shallow simulations as a benchmark for estimating uncertainty concerned the amplification factors. The simulation dataset comprises ensembles of about 50 000 scenarios each for six different sites and includes sensitivity studies related to the Manning friction. When analysing the entire ensembles, we have revised the previous mathematical model for the uncertainty treatment (Glimsdal et al., 2019, PAGEOPH) by normalising the ensemble scenario outputs with the median MIH from each simulation. We further measure the bias of the amplification factor method by measuring its offset towards median MIH output from the shallow water simulations. The model provides input to the probabilistic tsunami hazard (PTHA) map for Italy, and we present related results of the amplification factor uncertainty analysis here. We will also discuss further and advocate the use of the method, both for long term hazard (PTHA) and for rapid post assessment following an event, e.g. through the ARISTOTLE framework. This work is supported by the European Union’s Horizon Europe Research and Innovation Program under grant agreement No 101058129 (DT-GEO, https://dtgeo.eu/). Computational resources were made available through PRACE grant number 2020225386, TsuHazAP.
Inequality and driving factors in regional level energy-related CO2 emissions at a residential sector of Iran
Authors: Ata Behnam , Pakrooh Parisa , Pénzes János
Published: March 2024

An increasing amount of CO2 emissions from the household sector of Iran led us to analyze the inequality and understand the possible driving forces behind the CO2 emissions. The household sector in Iran contributes one of the largest sectors of CO2 emissions. The study of inequality provides information to policy‐makers to point policies in the right direction. By considering the differences in the socio‐economic factors of provinces, the study aims to analyze the inequality in CO2 emissions and different kinds of energy consumption, including oil, gas and electricity, for the household sector of Iran’s provinces between 2000 and 2019. Also, Household panel data of 28 provinces of Iran are employed by using both static and dynamic panel models for the years 2001 to 2019. This study investigates the relationship between CO2 emissions and the efficient factors in three major groups including energy, climate, and household socio-economic factors. the Theil index and Kaya factor, as a simple and common method, were considered to evaluate the inequality in both CO2 emissions and energy consumption, and determine the driving factor behind CO2 emissions. According to the results, inequality in oil and natural gas consumption were increasing, electricity was almost constant; however, CO2 emissions experienced a decreasing trend for the study period. The results of the Kaya factor indicate that the second factor, energy efficiency, with a 0.21 value was the main driving factor of inequalities in CO2 emissions. The empirical result of the static method showed a positive dependence of household CO2 emissions on Heating Degree Days (HDD), Cooling Degree Days (CDD), precipitation level, oil consumption, gas consumption, household income, size of household, and also building stocks. Also, removing the energy subsidy for fossil fuels due to substantial subsidy in fossil fuels in Iran or implementing a re-pricing energy policy can be a beneficial way to control carbon emissions from households within the provinces of the country.Behnam Ata is funded by the Stipendium Hungaricum scholarship under the joint executive program between Hungary and Iran.The study was elaborated under the research project TKP2021‐NKTA‐32 . 
Integrating machine learning with analytical surface energy balance model improved terrestrial evaporation through biophysical regulation
Authors: Bai Yun , Mallick Kanishka , Hu Tian , Zhang Sha , Yang Shanshan , Ahmadi Arman
Published: March 2024

Global evaporation modeling faces challenges in understanding the combined biophysical controls imposed by aerodynamic and canopy-surface conductance, particularly in water-scarce environments. We addressed this by integrating a machine learning (ML) model estimating surface relative humidity (RH0) into an analytical model (Surface Temperature Initiated Closure - STIC), creating a hybrid model called HSTIC. This approach significantly enhanced the accuracy of modeling water stress and conductance regulation. Our results, based on the FLUXNET2015 dataset, showed that ML-RH0 markedly improved the precision of surface water stress variations. HSTIC performed well in reproducing latent and sensible heat fluxes on both half-hourly/hourly and daily scales. Notably, HSTIC surpassed the analytical STIC model, particularly in dry conditions, owing to its more precise simulation of canopy-surface conductance (gSurf) response to water stress. Our findings suggest that HSTIC gSurf can effectively capture physiological trait variations across ecosystems, reflecting the eco-evolutionary optimality of plants. This provides a fresh perspective for process-based models in simulating terrestrial evaporation.
Circulation, mixing and heat transport in a Greenland fjord
Authors: Vries Anneke , Meire Lorenz , Mortensen John , Schulz Kirstin , van de Berg Willem Jan , van den Broeke Michiel
Published: March 2024

Greenland's glacial fjords transport heat and freshwater between the shelf and the outlet glaciers of the Greenland Ice Sheet. Therefore they are crucial to understand ice-ocean interaction in the Norhern Hemisphere. Despite increasing attention from the research community, much of the seasonal variability of fjord circulation remains unknown, especially in the non-summer months. This study presents current velocity and water mass data for a full year in Nuup Kangerlua. We provide insights into the dynamics of this South West Greenland fjord, focusing on winter and the upper layer currents. We show that in winter fjord circulation remains active, including a large cross fjord component that has not been observed before. There is a disconnect between the mouth and the inner part of the fjord, causing heat to be stored in the inner fjord. The stored heat could potentially act as reservoir of melt energy for glaciers in winter.
The influence of nitrogen and iron biogeochemical cycles on the production and export of dissolved organic matter in headwater catchments
Authors: Dupas Rémi , Lambert Thibault , Durand Patrick
Published: March 2024

Dissolved organic carbon (DOC) in surface waters originates mainly from riparian soils, where several processes affect the mobilisation/immobilisation of organic compounds. Among these processes, iron reduction is thought to be of primary importance for DOC mobilisation and export to surface waters. However, this process can be inhibited by the presence of nitrate due to its higher redox potential than Fe(III), making microbial nitrate reduction thermodynamically favourable compared to iron reduction. In agricultural catchments, the groundwater is typically enriched in nitrate. Thus, rising water tables in riparian areas during the (winter) wet season may inhibit iron reduction and the subsequent DOC mobilisation in soil and surface water. In this study, we tested this hypothesis in a well-monitored agricultural catchment belonging to the OZCAR network, the so-called Kervidy-Naizin catchment (5 km²). We installed 21 zero-tension lysimeters in the riparian zone of the catchment along three transects to sample soil solution in organic-rich top soil horizons (15 cm below the soil surface), at weekly to fortnightly intervals (oct 2022 – jun 2023). We analysed DOC, nitrate, Fe(II) concentrations as well as dissolved organic matter (DOM) composition through its optical properties (3D fluorescence coupled with PARAFAC modelling) to obtain information about DOM sources and dynamics across the hydrological cycle. We found that DOC concentrations were positively correlated with Fe(II) concentrations both spatially and temporally. In contrast nitrate concentrations were negatively related to Fe(II) in the soil solutions during the winter period. These observations support the hypothesis that nitrate is an inhibitor of iron reduction and subsequent DOC mobilisation. Data on the optical properties of DOM show that the DOC mobilised by this process contains large proportions of organic molecules of microbial origin, probably derived from the processing of soil organic matter. In addition, the mobilisation of high amounts of DOC unrelated to iron reduction in some zero-tension lysimeters suggests that other controls, such as wet-dry cycles, may be equally important for sustaining organic compounds in soil solutions and surface waters.
Turbulence intermittency effects on initiation threshold of sediment motion in natural waters 
Authors: Li Renzhi , Wang Yaping , Gao Shu
Published: March 2024

The initiation threshold of sediment motion, a key component in quantifying sediment transport, has potential link to intermittent turbulence bursts. Here, we elaborated in situ experiments on coastal sea bottom covered with cohesive sediments, to extract intermittency parameters. For the first time, waiting time between turbulence bursts was utilized to capture the occurrence of sediment initiation events. A relationship found between waiting time and shear stress reveals the different intermittency feature of sediment flux time series before and after reaching the threshold, which can be used to determine the initiation threshold of sediment motion. Multi-site results demonstrate the limitations of traditional empirical formulae for fine-grained sediments, where cohesiveness becomes more pronounced as grain size decreases and the deviation can reach 600%. The empirical formula was modified using grain size, and the modified calculations were in good agreement with observed values, which will greatly assist in sediment transport and geomorphology model predictions.
A monthly and daily 0.25° groundwater storage dataset in the Yangtze River Basin by assimilating GRACE/GRACE-FO data into the W3RA hydrological model
Authors: Wan Xuewen , Chao Nengfang , Yin Wenjie
Published: March 2024

Dynamic and accurate assessment of terrestrial water and groundwater is crucial for water resources management, agriculture and ecological environment protection. While the GRACE/GRACE-FO satellites have proven effective in monitoring large-scale terrestrial water storage anomaly (TWSA) and groundwater storage anomaly (GWSA), this study aims to enhance their spatial and temporal resolution for detecting the small-scale TWSA and GWSA in the Yangtze River Basin (YRB).
The main objectives and contents are as follows: 1) The daily/0.25° TWSA and GWSA are modeled using the W3RA hydrological model, incorporating factors such as rainfall, temperature, wind speed, and radiation; 2) The spatial correlation errors of GRACE/GRACE-FO data from 2002 to 2022 are considered, the uncertainties in the GRACE data over the YRB are obtained by the JPL; 3) The monthly and daily/0.25° TWSA and GWSA during 2002-2022 in the YRB is derived by accounting for the spatial correlation errors in the assimilation of GRACE/GRACE-FO into W3RA through the Ensemble Kalman Filter (EnKF) method; 4) Utilizing the results to quantify the spatiotemporal distribution of water resources in the YRB, the GRACE/GRACE-FO data signal serves as a valuable supplement to the model data. 5) The monthly and daily/0.25° GWSA will be further compared with in-situ well data to validate their accuracy. Furthermore, a quantitative analysis of the temporal and spatial evolution characteristics of GWSA in the YRB will be conducted.This study will provide valuable data and technical references for the dynamic monitoring of a small-scale TWSA and GWSA in the YRB and applications worldwide.
High vulnerability yet strong resilience of China's lakes to drought
Authors: Ma Siyu , Garcia-Garcia Almudena , Li Xueying , Peng Jian
Published: March 2024

Lakes play a crucial role in the global hydrological cycle and biogeochemical cycle. In China, lakes are an important part of water resources, providing 40.6% of drinking water. In recent years, droughts in the middle and lower reaches of the Yangtze River in China have led to a significant shrinkage of important freshwater lakes, such as Dongting Lake and Poyang Lake, posing a threat to local water security. However, there has been limited research on the extent to which thousands of lakes across China are affected by droughts. This study used remote sensing product of lake area to comprehensively investigate the impact of drought on the area of 4,702 lakes (natural lakes and reservoirs) in China from 1985 to 2018, covering the three stages of response, shrinkage, and recovery. The results indicate that lakes in China are highly vulnerable to drought. The average response probability of lakes is 72.8%, which typically occurs within six months to two years after the onset of drought. The shrinking area of the lake is 12.7% of the original area, and the shrinking process takes an average of 14 months. Lakes also show a strong resilience to drought, with 95.7% of lakes more likely to experience an increase in area following drought-induced shrinkage. However, only 49.4% of lakes are more likely to grow beyond their pre-shrinkage levels. Compared to natural lakes, artificial reservoirs exhibit a higher response probability by 4.6%, a larger shrinkage area percentage by 1.2%, and a higher recovery probability by 2.9%. Consequently, artificial reservoirs exhibit greater vulnerability and resilience to drought, reflecting the impact of human activities. Furthermore, the spatial distribution of vulnerability and resilience is inconsistent. In Northeast China, including the Songhua and Liaohe river basins, and the Mongolian endorheic basin, lakes exhibit higher vulnerability but lower resilience. Therefore, this region is considered a hotspot where the impact of drought on lake area is particularly severe. This study is expected to provide a basis for the implementation of sustainable water resource management and effective drought mitigation measures in China.
Innovative surface reflectance retrieval from UV satellites
Authors: Hedelt Pascal , Heue Klaus-Peter , Lutz Ronny , Romahn Fabian , Loyola Diego
Published: March 2024

The knowledge of the surface reflectance is essential for the retrieval of atmospheric trace-gases from satellites. It is required in the conversion of the observed trace gas slant column to the total vertical column by means of a so-called air-mass factor. Although there exists climatological databases based on UV satellite data (e.g. OMI, GOME-2), these have a low spatial resolution and are not appropriate for current and future UV satellite missions like Sentinel-5p/TROPOMI or MTG-S/UVN (Sentinel-4) due their significantly higher spatial and spectral resolution. Current climatologies which are used in operational retrievals provide the Lambertian Equivalent Reflection (LER, e.g. OMI, GOME-2, TROPOMI, see [1,2,3]) and Directional-LER (DLER, e.g. GOME-2, TROPOMI see [3,4]) for selected wavelength in the UV-VIS range and are based on the so-called minimum LER approach, i.e. determine the minimum surface reflectance in the measurement timeframe.We present here a new technique called GE_LER (Geometry-dependent Effective Lambertian Equivalent Reflectivity) based on Machine Learning, which retrieves the DLER from UV satellites in a wavelength range as opposed to the single wavelength approaches of existing climatologies. In this way, dedicated surface reflectivities for specific trace gas retrieval wavelength ranges can be determined. We train a Neural Network with simulated UV spectra, which have been calculated with (V)LIDORT (see [5]). This radiative transfer model is also used for the generation of Air Mass Factors in the operational TROPOMI trace gas retrieval. In this way we reduce the influence of using different radiative transfer models with respect to trace gas retrievals.First results of our GE_LER retrieval for several trace-gases based on TROPOMI data will be shown. References[1] Kleipool (2010), OMI/Aura Surface Reflectance Climatology L3 Global Gridded 0.5 degree x 0.5 degree V3, Greenbelt, MD, USA, Goddard Earth Sciences Data and Information Services Center (GES DISC),, 10.5067/Aura/OMI/DATA3006[2] Tilstra et al. (2017), Surface reflectivity climatologies from UV to NIR determined from Earth observations by GOME-2 and SCIAMACHY, J. Geophys. Res. Atmos. 122, 4084-4111, doi:10.1002/2016JD025940[3] Tilstra et al. (2021), Directionally dependent Lambertian-equivalent reflectivity (DLER) of the Earth's surface measured by the GOME-2 satellite instruments, Atmos. Meas. Tech. 14, 4219-4238, doi:10.5194/amt-14-4219-2021[4] Tilstra et al. (2023), A directional surface reflectance climatology determined from TROPOMI observations, Atmos. Meas. Tech. Discuss. [preprint], doi:10.5194/amt-2023-222, in review[4] Spurr et al. (2008), LIDORT and VLIDORT: Linearized pseudo-spherical scalar and vector discrete ordinate radiative transfer models for use in remote sensing retrieval problems. Light Scattering Reviews, Volume 3, ed. A. Kokhanovsky, Springer
Regionalized nitrogen balances of Switzerland
Authors: Gilgen Anina , Baumgartner Simon , Spiess Ernst , Liebisch Frank
Published: March 2024

For the agri-environmental monitoring of Switzerland, nitrogen balances on farm level for all Swiss farms were calculated and aggregated in order to obtain regionalized nitrogen balances. This monitoring attempts to incorporate as much existing data as possible to minimize multiple data collections from farmers. Data from the agricultural policy information system of Switzerland was used as basis for the calculation. This database contains information on livestock numbers, the crops grown, and the direct payments received for each farm. This information was supported with different data sources from federal offices, cantons, agricultural associations, and research institutions. Balances were calculated as a soil-surface balance according to the OECD method, which includes N input via organic and mineral fertilizers, biological N-fixation, atmospheric N-deposition, and seedlings as well as N outputs via plant yields.The regional balances showed a high variability, resulting in an average N surplus of around 105 kg N per hectare of utilized agricultural area in cantons with highly intensive livestock farming and around 16 kg N in cantons with more extensive farming practices, i.e. in mountain regions. On national scale, highest N input occurred via organic fertilizers, whereas mineral fertilizers and biological N-fixation account for around 15% of the total input each.Our approach of calculating N balances on farm level for the whole Swiss farming system has some limitations, which are mainly due to missing or incomplete data sources.  As an example, the use of mineral fertilizers had to be estimated by application data of a rather small sample of farms (~300 farms). Nevertheless, the obtained results show that this methodology is a promising tool to gain a regional overview of the environmental status of Swiss farms. Over the years, this approach will be refined and new data (e.g. additional administrative data, satellite data) can be incorporated in order to better estimate the N balances of Swiss farms.
Human pressure on global land ecosystems and biodiversity increases notably from 1990-2020 - Development of a spatially explicit Biodiversity Pressure Index (BPI)
Authors: Ramm Katharina , Brown Calum , Arneth Almut , Rounsevell Mark
Published: March 2024

The loss of biodiversity from human activities on land is a widely-recognized, worldwide problem. Since the advent of the industrial revolution the loss of plant and animal species has increased dramatically, with 25% of species now at risk of extinction. Conventions and targets to protect biodiversity have been implemented, but with limited success. The Aichi targets for 2020, for example, were almost all missed, with worsening trends for 12 out of the 20 targets. One reason for this failure is the ineffective application of broad-scale measures that are not tailored to the underlying causes of biodiversity loss. Knowledge on the spatial and temporal distribution of anthropogenic drivers of biodiversity loss would therefore enable targeted interventions that address location-specific stressors and thus would be better-adapted measures to protect biodiversity.The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) has identified five main drivers of anthropogenic origin as the causes of biodiversity loss: land use, natural resource extraction, climate change, pollution, and invasive alien species. However, when seeking to quantify impacts on biodiversity, these drivers are still usually treated separately. We develop a Biodiversity Pressure Index (BPI) by quantifying and mapping data for nine indicators of the five drivers into a single, annually changing index with a spatial resolution of 0.1° at global scale covering the period 1990-2020. We find that large areas (approximately 86%, including Antarctica, Greenland) are under major human pressure and that almost all areas have experienced an increase (about 96% of land) in pressure over the past thirty years. Industrialised regions had high pressure levels already in 1990 and continue to do so in 2020, whereas regions with rapid economic growth setting in after 2000 where low in pressure in 1990, but show high pressure levels today. Whilst areas impacted by human activities are increasing, areas of wilderness are decreasing to a point that in 2020, only 0.02% of the terrestrial land are entirely free from human influence. (Sub-) tropical wetlands and temperate grasslands are the biomes with the highest pressures today. And whilst land use is still one of the main factors, climate change - especially increasing temperature - is one of the major recent and future threats to biodiversity.