bluuebunny/crossref_metadata_2025 huggingface dataset:
Cloud Droplet Number Concentration: Satellite Retrievals Improved by Advanced Atmospheric Modelling
Authors: Siméon Alexandre , Gonzalez Jessenia , Sourdeval Odran
Published: March 2024

The cloud droplet number concentration (CDNC) is one of the most important microphysical properties of liquid clouds for understanding and quantifying the effective radiative forcing by aerosol-cloud interactions (ERFaci). Indeed, CDNC is linked to the relevant processes of the cloud formation and evolution. CDNC is closely related to the chemical composition of the condensation nucleation nuclei and the cloud droplet size distribution. Nevertheless, this key parameter remains poorly known. CDNC is not yet operationally provided from current standard satellite retrievals. Our approach relies on an innovative determination of CDNC from satellite observations in combination with atmospheric cloud-resolving modelling. We introduce our new, community-based tool: the Satellite Simulator and Sandbox for Cloud Observation and Modelling (S3COM). Briefly, S3COM aims to simulate realistic satellite observations and cloud products from model outputs, to quantify the sensitivity of radiative quantities to cloud parameters, and to assist the development of retrieval algorithms using output fields from high-resolution models. We use realistic cloud situations (stratocumulus, cumulus, marine and continental clouds) obtained from the ICOsahedral Nonhydrostatic Large Eddy Model (ICON-LEM) to simulate top of atmosphere radiances with the Radiative Transfer for TOVS (RTTOV), from visible to infrared, observed by the Moderate Resolution Imaging Spectroradiometer (MODIS). Performance of MODIS-type algorithms coupled with ICON-LEM simulations is described and characterization of error sources is given. Results on CDNC retrievals for warm liquid water stratocumulus clouds are presented and discussed for the study case of the 02 May 2013.
Space-Domain Forward Modeling-Based Inversion Algorithm for Two-Dimensional Controlled Source Electromagnetic Method
Authors: Chauhan Iktesh , Dehiya Rahul
Published: March 2024

Conventionally, two-dimensional (2D) modelling of controlled-source electromagnetic (CSEM) data is executed in the wavenumber domain to efficiently overcome the complexity arising due to the 3D nature of the source. However, the wavenumber domain approach is challenging to implement as it requires inverse Fourier transform to get a response in the space domain. To address this complexity, a new algorithm in which the governing Helmholtz equation is solved in the space domain is developed. To perform an efficient space domain 2D CSEM modelling, we develop a strategy that requires a small number of grids to discretize space in the strike direction. We achieve this goal by devising a set of boundary conditions on the plane perpendicular to the strike direction that passes through the source position. The even and odd characteristics of the electric and magnetic fields are exploited to derive these boundary conditions for different source types. Furthermore, it is observed using benchmarking experiments that less than ten grids are sufficient in the strike direction to obtain an accurate response, even for a reasonably complex 2D resistivity model. Additionally, inverse modeling based on the Gauss-Newton optimization method, which uses the proposed modeling scheme for both forward and adjoint calculations, is developed. Numerical inversion experiments using both synthetic and real-field data reaffirm the robustness and versatility of the designed algorithm. The inversion studies agree with the benchmark analysis of forward responses, indicating that a minimal number of grids (approximately eight) are sufficient to discretize space along the strike direction. Hence, the system matrix of the proposed algorithm typically will have roughly eight times more non-zero elements than a single wavenumber domain simulation with the same discretization of the plane perpendicular to the strike direction. However, one needs tens of wavenumber domain simulations to get the response in the space domain. Consequently, the proposed algorithm provides a simple and efficient alternative to wavenumber domain simulation of 2D CSEM data and inversion.
Imaging hydrothermal alteration with electrical resistivity tomography in La Soufrière de Guadeloupe volcano
Authors: Mendieta Aida , Rosas-Carbajal Marina , Bajou Raphaël , Baud Patrick , Deroussi Sébastien , Esposti Ongaro Tomaso , Komorowski Jean-Christophe , Kushnir Alexandra R.L. , Villeneuve Marlène , Heap Michael J.
Published: March 2024

Hydrothermal alteration plays a major role in volcanic instability. Improving techniques that allow us to better understand the timescales of alteration in active volcanoes is thus paramount. Since the reactivation of the fumarolic field at the top of the dome of La Soufrière de Guadeloupe (Guadeloupe, France) in 1992 and the expansion of its surface area in recent years, the area of study is subjected to prolonged variable alteration that has promoted past flank collapses and can also influence permeability and thus shallow depth overpressurization. During a field campaign in May 2022 we performed 25 electrical resistivity tomography (ERT) profiles in the summit of La Soufrière, next to active fumaroles and acid boiling ponds. These ERT profiles were inverted using the open-source code pyGIMLi. Thanks to the ERT profiles we are able to roughly map the altered areas to a depth of about 20 m in this zone of La Soufrière. Some of the byproducts of alteration that have been identified in La Soufrière are clays, sulfates and pyrite. Thus, we infer that the low electrical resistivity zones (1500 Ωm) corresponds to unaltered rock. Low electrical resistivity anomalies are observed north of the Breislack fault, near the fumaroles. The explored north-most region is characterized by higher values of electrical resistivity. We take into account ground temperature and spatial variability to interpret the electrical conductivity anomalies and we use this first high-resolution resistivity model to plan a repetition of our experiment. This time-lapse experiment will allow us to estimate the evolution of hydrothermal alteration in the volcano’s summit over a 2-year period in the context of the current ongoing multiparameter unrest.
Forming rocky exoplanets around K-dwarf stars
Authors: Hatalova Petra , Brasser Ramon , Mamonova Elena , Werner Stephanie
Published: March 2024

How multiple close-in super-Earths form around stars with masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the search for extraterrestrial life. We aimed to reproduce the currently known population of close-in super-Earths observed around K-dwarf stars and their system characteristics. Additionally, we investigated whether the planetary systems that we formed allow us to decide which initial conditions are the most favorable. We performed 48 high-resolution N-body simulations of planet formation via planetesimal accretion using the existing GENGA software running on GPUs. In the simulations we varied the initial protoplanetary disk mass and the solid and gas surface density proﬁles. Each simulation began with 12000 bodies with radii of between 200 and 2000 km around two different stars, with masses of 0.6 and 0.8 MSun. Most simulations ran for 20 Myr, with several simulations extended to 40 or 100 Myr. The mass distributions for the planets with masses between 2 and 12 MEarth show a strong preference for planets with masses Mp < 6 MEarth and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetary systems and produce mostly long-term angular-momentum-deﬁcit-stable, nonresonant systems, but we required an initial disk mass of 15 MEarth or higher and a gas surface density value at 1 AU of 1500 g cm-2 or higher. Our simulations also produced many low-mass planets with Mp < 2 MEarth, which are not yet found in the observed population, probably due to the observational biases. Earth-mass planets form quickly (usually within a few million years), mostly before the gas disk dispersal. The ﬁnal systems contain only a small number of planets with masses Mp > 10 MEarth, which could possibly accrete substantial amounts of gas, and these formed after the gas had mostly dissipated.
Global economic impact of weather variability on the rich and the poor
Authors: Quante Lennart , Willner Sven , Otto Christian , Levermann Anders
Published: March 2024

The distribution of temperature and precipitation has been shown to impact economic productivity all around the world.These heterogeneous patterns change under future warming and impact consumers not only locally but also remotely through supply chains. Due to the possibility of a non-linear economic response, these effects are difficult to quantify and have been subject to limited empirical assessment focusing on direct impacts of weather extremes.Here we show in numerical simulations of weather-induced production disruptions (of more than 7000 profit-maximising producers and utility-optimising consumers with more than 1,8 million supply linkages) that, under present-day climatic conditions, consumption loss risks resulting from production disruptions propagating through the economic network are larger for lower than for higher income groups within countries. Comparison between countries shows that risks are larger for medium-income countries than for low and high-income countries, which emerges from differing trade dependencies as well as heterogeneous exposure and response.Projecting observed econometric relations of weather variability and economic productivity until 2040, we find an amplification of loss risks due to near-term climate change in most regions. This amplification increases with income for middle and high-income countries, while it is homogeneous across income groups in low-income countries. Global warming thus poses an increasing challenge to consumers through supply chains around the globe which needs to be addressed by fostering resilience. To avoid further harm to productivity and consumer welfare the climate has to be stabilised. 
Multiproxy analyses for a network of firn cores covering the last 40 years from coastal Adélie Land 
Authors: Tcheng Titouan , Fourré Elise , Baubant Léa , Lassalle-Bernard Coralie , Jacob Roxanne , Parrenin Frédéric , Jossoud Olivier , Prié Frédéric , Minster Bénédicte , Agosta Cécile , Leroy-Dos-Santos Christophe , Casado Mathieu , Bouchet Marie , Favier Vincent , Magand Olivier , Lemeur Emmanuel , Picard Ghislain , Cauquoin Alexandre , Werner Martin , Landais Amaelle ,   ASUMA RAID team
Published: March 2024

Water stable isotopes signals recorded in snow, firn and ice cores were successfully used to investigate past temperatures on glacial/interglacial scales (Jouzel and Masson-Delmotte 2010, Dansgaard, 1964). However, as evidenced by Goursaud et al. (2018) in coastal Adélie Land, many uncertainties hampered the interpretation of water isotope records at sub-annual to decadal resolution as a proxy of past temperature variations only (Goursaud et al. 2018). Condensation, sublimation and/or redistribution of snow triggered by strong katabatic winds as well as precipitation intermittencies, origin of moist air masses bringing precipitation and diffusion within firn lessen the representativity of a single isotopic profile to reconstruct past temperature in this region (Grazioli et al. 2017, Khale et al. 2018, Picard et al. 2019, Casado et al. 2020, Hirsch et al. 2023). In order to mitigate the non-representativity of a single isotopic profile, a solution consists in averaging several records to increase signal to noise ratios. However, to do so, it is necessary to provide a good correspondence between the different cores of interest.In this study, we make good use of water stable isotopes and major chemistry records from 9 firn core (20 to 40m deep) drilled at 3 sites (so called D47, Stop5 and Stop0) during the ASUMA campaign. These sites display a high mean accumulation rate of about 250 mm.weq/year and a wide range of environmental conditions with elevation ranging from 1550m to 2460m, distance from coast ranging from 103km to 423km and different katabatic winds influence. In particular, we use the Paleochrono probabilistic model with water stable isotopes signal and major chemistry records coupled with beta-gamma and RADAR data to obtain the best correspondence between the different cores. We then quantify to what extent the stacking of several cores enable to increase the signal to noise ratio at the different sites and can provide a faithful record to document variations of the temperature and/or atmospheric water cycle over the last decades in this region.
Vegetation Submergence Effects on Bedload Transport Rate
Authors: Lu Yesheng , Cheng Nian-Sheng , Wei Maoxing , Ancey Christophe
Published: March 2024

We conducted a series of laboratory experiments to investigate the impact of vegetation on bedload transport rates depending on submergence. In the experiments, we used aluminum rods to simulate rigid vegetation, with vegetation submergence ratios (i.e., the ratio of water depth to vegetation height) ranging from 1 to 2. The bedload transport rates were measured by collecting sediment at the end of the vegetated area. The findings indicate that, with a constant bulk-averaged flow velocity, bedload transport rates decrease as the submergence ratio increases. This decrease is attributed to changes in the flow velocity distribution resulting from the flow resistance exerted by submerged vegetation. Indeed, water flows more easily through the top of the vegetation, and concurrently water velocity decreases significantly in the bottom region occupied by the vegetation. Building upon the phenomenological theory of turbulence, we propose a hydraulic radius-based method for estimating bed shear stress by incorporating the submergence ratio effect. This model enables the application of Cheng’s (2002) bedload formula, originally developed for bare beds, to predict bedload transport rates in both emergent and submerged vegetated flows. The present model, calibrated with a single parameter from experimental data, exhibited an average relative error of about 400% when validated with using experimental data (275 data in all) from our study and the relevant literature.
Flood Mapping Using High-Resolution Topography and Crowdsourced Data with the Geomorphic HAND Approach in Rural Plains
Authors: Sabeh Hassan , Tournoud Marie-George , Chahinian Nanée , Abdallah Chadi , Moussa Roger , Hdeib Rouya
Published: March 2024

Flood mapping is essential for risk management and emergency response. The most common approach is hydraulic modelling, a method that is still challenging and demanding in terms of data and computation. Low complexity models are an increasingly adopted alternative that are capable of achieving good results while using minimal data input and low calculation time. Yet, the reliability and effectiveness of such approaches remain unclear in flat and engineered plains. In this study we aim to optimize flood hazard mapping based on the Height Above Nearest Drainage (HAND) geomorphic approach by utilizing a high-resolution digital elevation model (15 cm) with crowdsourced data. The approach is tested on the Ostouane river basin (144 km2) in Lebanon, and validated using crowdsourced data of the January 2019 flood, which was the most intense flood within the past decade. The workflow begins by developing a database of spatial and topographic information, including the digital elevation model, bathymetry, land use and crowdsourced flood depths. Five scenarios representing different terrain configurations with varying levels of hydro-conditioning and feature inclusion (e.g. bathymetry, canals and levees) are simulated. The model’s thresholding is then optimized by integrating rating curves produced by 1D HEC-RAS hydraulic model to assess and correct HAND based synthetic rating curves (SRC). Results shows that extensive hydro-conditioning is necessary to improve the inundation extents within the floodplains. Correcting synthetic rating curves is essential to overcome errors produced by terrain conditioning. Overall, the model is able to yield high accuracy of flood extent when ensuring hydrologic connectivity between the river and floodplain and within the floodplain itself. Our findings indicate that leveraging high-resolution topography and crowdsourced inputs can enhance the accuracy of flood mapping results. However, achieving this precision necessitates a meticulous optimization procedure.
Ammonium nitrate and biomass burning pollution in the UTLS: First results from GLORIA airborne measurements of Asian Monsoon outflow during the PHILEAS campaign 2023
Authors: Johansson Sören , Wetzel Gerald , Höpfner Michael , Braesicke Peter , Friedl-Vallon Felix , Glatthor Norbert , Kleinert Anne , Neubert Tom , Preusse Peter , Riese Martin , Sinnhuber Björn-Martin , Ungermann Jörn , Versick Stefan ,   the GLORIA team
Published: March 2024

We present trace gas and aerosol measurements obtained by the airborne infrared imaging limb sounder GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) that has been operated onboard HALO (High Altitude and Long Range Research Aircraft) during the PHILEAS campaign (Probing High Latitude Export of air from the Asian Summer Monsoon ; August-September 2023). We measured outflow from the Asian Monsoon above the North Pacific, and the Mediterranean, as well as pollution plumes from biomass burning events in North America. In this contribution, we present retrieval results of ammonia (NH3), solid ammonium nitrate and other pollution trace gases (e.g. PAN) as two-dimensional distributions with high vertical resolution, derived from GLORIA observations in the UTLS (Upper Troposphere Lower Stratosphere).Our GLORIA observations reveal considerable abundances of solid ammonium nitrate, which is connected to the Asian Monsoon, in the lower stratosphere outside the Asian Monsoon Anticyclone. Measurements from a previous airborne campaign within the Asian Monsoon (StratoClim 2017) showed large enhancements of NH3 (precursor of ammonium nitrate), and solid ammonium nitrate in the Asian Monsoon upper troposphere.Further, GLORIA measured UTLS air masses heavily influenced by biomass burning during PHILEAS. Due to the ability of GLORIA to measure pollution trace gases with different atmospheric life times, we are able to estimate the age of individual plumes, based on their chemical composition. As an example, we show measurements from a PHILEAS flight, influenced by aged and fresh pollution.In a first analysis, we compare our measurements with atmospheric models to examine air mass origins. In particular, we use artificial tracers calculated by the ICON-ART (ICOsahedral Nonhydrostatic - Aerosol and Reactive Trace gases), one of the models that was also used in forecast configuration for flight planning.
Evaluation of different methods for detecting 'kalte Dunkelflaute' events with respect to climate change projections
Authors: Biewald Benjamin , Zappa William
Published: March 2024

Weather-driven periods of low electricity production from renewable energy sources (RES) can result in so-called ‘energy droughts’, sometimes known by the German term ‘Dunkelflaute’. When these weather phenomena occur over a large geographical area for extended periods of time, and coincide with periods of high electricity demand due to cold temperatures (‘kalte Dunkelflaute’), these events pose a risk for maintaining resource adequacy in a future power system relying significantly on RES.The most robust way of identifying energy droughts is to use hourly electricity market simulations to capture both the demand- and supply-side effects of different climate years, but these simulations are computationally intensive to perform and Transmission System Operators (TSOs) can typically only consider 30-40 historical climate years in resource adequacy studies. However, as vastly more climate data is becoming available from future climate projections, a robust way to identify ‘kalte Dunkelflauten’ from climate data alone is needed in order to identify challenging years to consider in resource adequacy studies. A variety of approaches for defining and analysing energy droughts can be found in the literature such as those which detect singular events by defining a threshold for renewable energy production (production drought) or how much (net) load is covered by RES (supply drought) (e.g. Raynaud et al., 2018), and those which use statistical methods to assess the risk of an energy drought within a predefined timespan (e.g. Ruhnau & Qvist, 2022). However, there is no clear consensus on which is the best method.In this study we will present an evaluation of different methods to assess the risk of occurrence of such ‘kalte Dunkelflaute’ events, and validate these methods by comparing with results from detailed hourly simulations, with a focus on the Netherlands and Germany. By applying different detection methods to both existing and projected RES capacity, and using both historical and future climate data from a Pan-European Climate Database, we compare past and future risks posed by energy droughts.  As extreme ‘Dunkelflaute’ events are rare but their impact may be severe, comparing different approaches of how to statistically evaluate these events is an important contribution to evaluating resource adequacy, and assessing the resilience of the future energy. ReferencesRaynaud, B. Hingray, B. François & J.D. Creutin (2018). Energy droughts from variable renewable energy sources in European climates. Renewable Energy, 125, 578-589, https://doi.org/10.1016/j.renene.2018.02.130.
Ruhnau & S. Qvist (2022). Storage requirements in a 100% renewable electricity system: extreme events and inter-annual variability. Environmental Research Letters, 17(4), 044018, https://doi.org/10.1088/1748-9326/ac4dc8
Illuminating active fault zones at Campi Flegrei Caldera (Southern Italy) from high-precision earthquake locations
Authors: Scotto di Uccio Francesco , Lomax Anthony , Natale Jacopo , Muzellec Titouan , Festa Gaetano , Nazeri Sahar , Convertito Vincenzo , Bobbio Antonella , Strumia Claudio , Zollo Aldo
Published: March 2024

The Campi Flegrei caldera, located to the west of the city of Naples, is one of the most active and urbanized volcanic areas in the world, also hosting an eruptive episode in historical times. This area periodically experiences notable unrest episodes which include ground deformations and seismic swarms, as in the recent 1982-1984 crisis. During the past decade, the central portion of Campi Flegrei caldera underwent a sustained and continuous ground uplift reaching rates of 15 mm/month, along with an increase in the rate, maximum magnitude and spatial extent of seismicity especially in the last two years, culminated with the occurrence of an Md 4.2 earthquake on 27th September 2023.In this study, we compute high-precision earthquake locations using multi-scale, source-specific station corrections and waveform coherence. We relocated ~8.3 k earthquakes between 2014 and 2023, resulting in hypocentral uncertainties less than ~ 100 meters and thus assessing the spatiotemporal evolution of the earthquakes during the current crisis. We show that the integration of the station corrections and the coherence-driven, cross-correlation weighted stack of the probabilistic locations for nearby events (< 2km) strongly improves the location accuracy for target earthquakes. Relocated hypocentres allow us to clearly show with unprecedented detail the complexity of the kilometric-size fault structures activated in response to the increasing rate of the ground uplift phenomenon. Most of the seismicity is clustered along identifiable segments concentrated in a shallow region around the Solfatara-Pisciarelli area, where epicentres define an ~1x1 km, horseshoe-shaped structure, opened and deepening toward the northeast.  In contrast, the deepest offshore seismicity, between 3-5 km depth, appears to fit and approximate the downward propagation of the previously identified south-western caldera inner ring fault. Relocated seismicity appears coherent with the fracture zones activated during the 1982-84 unrest episode. However new sectors of activity have been identified during the present unrest, including the one at the eastern boundary, which hosted the largest Md 4.2 event caused by a km-size rupture within the shallow (3 km) volcanic sedimentary layer. Given the size of the structures mapped in this study and the source parameters estimated for the main event, these faults can accommodate earthquakes of moment magnitude up to 5.0, both around the Solfatara and the offshore, south of Pozzuoli, significantly increasing the hazard in the area.
Towards the Quantification and Attribution of Anthropogenic CH4 Fluxes based on Airborne Lidar and Passive Measurements over the Lloydminster Oil and Gas fields
Authors: Fruck Christian , Wolff Sebastian , Krautwurst Sven , Kiemle Christoph , Kanzler Leah Marie , Quatrevalet Mathieu , Wirth Martin , Fix Andreas , Borchardt Jakob , Huhs Oke , Ehret Gerhard , Bovensmann Heinrich
Published: March 2024

The CoMet 2.0 Arctic airborne measurement campaign of 2022 targeted a variety of natural as well as anthropogenic sources of CH4, mostly in Canada, such as landfills, coal mines, power plants or fossil fuel exploitation sites. Many anthropogenic emission targets consist of a few strong emitters with small or negligible spatial extension. In these cases, emission plumes can readily be observed by passive imaging spectrometers, through the observed enhancement in column averaged CH4. However, over oil and gas fields such as the Lloydminster area at the Alberta/Saskatchewan border, with numerous individual wells extending over large areas, this is much more difficult since individual plumes are lower in magnitude and may even overlap. In such cases it may not be possible to resolve plumes from individual sources, but the total flux can still be estimated using a budget approach. Nevertheless, limitations arise from spatial and temporal variations in the wind field, regarding proper quantification of the source strengths.In this contribution we present our strategy for source attribution, combining measurements by the airborne CHARM-F greenhouse-gas lidar and the MAMAP2DL imaging spectrometer with emission inventories and inverse modeling. A similar approach has already been successfully applied to CHARM-F data recorded over the Upper Silesian Coal Basin during the CoMet 1.0 campaign. CHARM-F is an Integrated-Path Differential-Absorption (IPDA) lidar that provides vertical column concentrations of CO2 and CH4 up to the flight altitude along the flight track. The advantages of lidar are the insensitivity to illumination conditions and a low intrinsic bias. MAMAP2DL is a passive airborne push broom imaging spectrometer that measures spatially resolved changes in relative column concentrations of CH4 and CO2. During the CoMet 2.0 Arctic campaign in August and September 2022, CHARM-F and MAMAP2DL have been deployed onboard the German research aircraft HALO, alongside a suite of complementary instruments for in-situ measurements of CH4, CO2 and other trace gases. We introduce our methods for data treatment and inverse modelling and show first results from this approach.
Droughts influence changes in human settlement patterns in Africa
Authors: Ceola Serena , Maard Johanna , Di Baldassarre Giuliano
Published: March 2024

Human displacements due to climate and weather extremes are dramatically increasing worldwide, mainly across areas where extreme events interact with high vulnerability and low adaptive capacity, such that they are now recognized as a primary humanitarian challenge of the 21st century. Human mobility from droughts is multifaceted and depends on environmental, political, social, demographic and economic factors. Although droughts cannot be considered as the single trigger, they significantly influence people's decision to move. Yet, the ways in which droughts influence patterns of human settlements have remained poorly understood.Here we explore the relationships between drought occurrences and changes in the spatial distribution of human settlements across 50 African countries for the period 1992–2013. Since long-term yearly data on human displacements are not consistently available for the entire African continent, we employ both country-based and spatially explicit data sets as reliable proxies. We base our continental study on urban population data and nighttime lights, as a proxy for the spatial and temporal distribution of human settlements. For each country, we evaluate annual relative urban population and human distance to rivers. To identify drought years, we extract annual drought occurrences from two indicators, the international disaster database EM-DAT and the standardized precipitation evapotranspiration index (SPEI-12) records. We then compute human displacements as variations in human distribution between adjacent years, which are then associated with drought (or non-drought) years. We finally examine the consistency between drought occurrences and changes in human settlement patterns to identify macroscopic trends at the continental scale.Our results show that drought occurrences across Africa are often associated with (other things being equal) human mobility toward rivers or cities. In particular, we found that human settlements tend to get closer to water bodies or urban areas during drought conditions, as compared to non-drought periods, in 70%–81% of African countries.This large-scale trend clearly highlights that the occurrence of drought events, although not being the single driving factor, significantly influences human mobility. By interpreting this outcome from a broader perspective, which includes consecutive drought-to-flood events, adverse consequences might occur. An increased human presence in urban areas and close to rivers may result into an increased human exposure to floods, and thus leading to a potentially increased flood risk. Therefore, further investigations are foreseen and encouraged to better understand the interplay between human mobility and climate change in order to increase the resilience of vulnerable areas and population to hydrological extreme events and support the development of sustainable and effective planning strategies for the near future.
Effects of topsoil removal on greenhouse gas exchange of fen paludicultures
Authors: Köwitsch Philipp , Tiemeyer Bärbel , Antonazzo Sonia , Dettmann Ullrich
Published: March 2024

Current agricultural practices on peatlands require drainage, leading to substantial emissions of the greenhouse gases (GHGs) carbon dioxide (CO2) and nitrous oxide (N2O). Paludiculture is an option to mitigate these adverse environmental impacts while maintaining productive land use. Whereas the GHG exchange of paludiculture on rewetted bog peat, i.e., Sphagnum farming, is relatively well examined, data on GHG emissions from fen paludicultures remain scarce. Considering that typical fen paludiculture species are aerenchymous plants, the release of methane (CH4) is a crucial aspect when optimizing the GHG balance of such systems. One potential method to reduce CH4 emissions upon rewetting involves removing the topsoil, but retaining a nutrient-rich topsoil might foster the biomass growth.In this project, Typha angustifolia, Typha latifolia, and Phragmites australis are grown at a fen peatland formerly used as grassland. Water levels are maintained at the surface or slightly above it. In parts of the newly created polder surrounded by a peat dam, approximately 10 cm of topsoil had been removed before planting. In order to separate the effects of topsoil removal and water level, four smaller sub-polders were installed. Here, the water levels can be adjusted independently from the main polder. Greenhouse gas exchange is measured for all three species with and without topsoil removal. Additionally, a reference grassland site close by and a site on the dam are included in the measurements. Using manual transparent and non-transparent chambers and a portable analyser for both CH4 and CO2, GHG measurements are carried out every two to four weeks on a campaign basis. N2O is measured using non-transparent chambers and gas chromatographic analysis. Here, we present GHG balances of the first three years after planting the paludicultures.Challenges in water management during the initial year after planting caused an infestation with Juncus effusus, especially at the Phragmites australis sites. However, despite suboptimal water levels in the first year, all paludiculture species were a net CO2 sink, irrespective of topsoil treatment. During this period, fluctuating water levels led to very low CH4 emissions, whereas N2O emissions played a more significant role in the GHG balance. Even under more stable hydrological conditions in the second year, CH4 emissions remained rather low, leading to a GHG sink for almost all paludiculture species, even including the first harvest year. Therefore, the current results of our study do not indicate topsoil removal to be necessary as a significant optimization strategy concerning CH4 emissions in fen paludiculture.
Monitoring groundwater dynamics in a mountain ridge using seismic interferometry: Influence of topography, local subsurface structure and meteorological conditions.
Authors: Illien Luc , Kuehn Jannik , Andermann Christoff , Hovius Niels
Published: March 2024

Groundwater storage monitoring is now one of the most promising application of seismic interferometry techniques. In steep mountain environments, where drilling wells is particularly challenging, the use of seismic stations to retrieve relative seismic velocity changes could fundamentally advance our understanding of groundwater dynamics. However, very few studies have looked at seismic velocity variations at the scale of a single steep topography unit. Here, we estimate velocity variations from six stations covering a distance of 3.5 km on a single mountain ridge in the county of Hualien, Taiwan. One station was placed at the top of a ridge (900m elevation), two at the mid-slope of the topography and two others at the bottom (200m elevation), near the river banks. The aim is twofold: Determining how homogenous these velocity changes are and understanding the possible impact of topography on groundwater variations in a mountainous setting. Results from auto-correlations and cross-correlations are compared with meteorological data and other geophysical analysis. We identify the average hydrological dynamics of the ridge unit and connect the residual velocity changes to local site characteristics and upstream weather conditions.
The influence of anthropogenic topographic changes on geomorphological processes in the city of Rome (Italy)
Authors: Delchiaro Michele , Vergari Francesca , Esposito Carlo , Del Monte Maurizio
Published: March 2024

The urban landscape of the city of Rome exhibits a discernible urban-rural gradient, characterized by a diminishing anthropic impact from the central historic city to the outskirts and peri-urban zones, marked by increased open spaces and green areas. In the Aeterna Urbs, the Anthropocene epoch has seen significant urbanization and infrastructure development, frequently leading to profound alterations or complete obliteration of natural landscapes. The distinctive anthropogenic changes observed in Rome, characterized by their unique features, are not confined to the city; they are also evident in other contexts, underscoring commonalities and interconnections in how human activity shapes the landscape. In this regard, the city of Rome stands as an exemplar, offering a unique opportunity to delve into the human-induced changes and their impact on the natural geomorphological processes. However, despite their critical importance in understanding human-landscape interactions and the associated geomorphological risks, the role of human activity as a morphogenetic agent along the urban-rural gradient remains inadequately understood. This study addresses the tricky understanding of human-induced geomorphic changes, particularly on erosion, transport, and sedimentation processes, which pose threats to ecosystem functioning and impede efficient land use. The Malagrotta extraction area in Rome, Italy, characterized by a mining landscape of ridge removal, hillslope terracing and valley filling, offers a unique opportunity to assess the impact of topographical alterations on the geomorphic system. The investigation employs the widely accepted functional relationship between drainage area (A in m2) and slope (S in m/m) to delineate local process domains and facilitate the interpretation of process interactions. The slope-area function is applied to the same watershed across different periods using digital elevation models, offering insights into the evolving geomorphic dynamics influenced by human activities.
Ground Deformation Monitoring Using InSAR and Hydrological Time Series and Least-Squares Wavelet Software: A Case Study in Catania, Italy
Authors: Ghaderpour Ebrahim , Scarascia Mugnozza Gabriele
Published: March 2024

Studying water level fluctuation is crucial for water resource management and infrastructures. Groundwater level variations are due to recharge and/or discharge of water from aquifer because of anthropogenic activities or natural processes, e.g., rainfalls, irrigations, etc. Such variations may have a direct impact on ground deformation in the form land subsidence, land uplift, or landslide. Persistent Scatterers Interferometric Synthetic Aperture Radar (PS-InSAR) is an advanced satellite remote sensing technique which allows an effective monitoring of ground movement. In this work, PS-InSAR time series as well as precipitation and hydrological time series in a region in Catania, Italy are utilized, and their possible interconnections are investigated in the time-frequency domain using the tools in the least-squares wavelet software. It is shown how water level (surface water and groundwater) variations may have an impact on ground deformation.
Kinematics of Intra-Plate Strike-Slip Earthquakes in an Oblique Convergent Setting  : Insights from the Eastern Himalayan and Indo-Burman Plate Boundary Systems
Authors: Chaudhuri Dibyajyoti , Banerjee Rupak , Mahanti Sankha Subhra , Kumar Ajay , Mitra Supriyo
Published: March 2024

North-East India comprises a part of the eastern extremity of the Alpine-Himalayan Belt and is one of the most rapidly deforming regions owing to its unique geological setup. The tectonics of this region is dominated by oblique convergence between two nearly perpendicular plates and results in a zone of distributed deformation. This region is associated with a large number of intra-plate strike-slip and oblique-slip (thrust) earthquakes which are not related to any of the plate boundaries. In this study we model the source mechanisms of five recent strong-to-moderate earthquakes (5.5≥Mw≤6.0) using teleseismic P and SH waveforms inversion and use source directivity and back-projection of the high-frequency energy from multiple teleseismic arrays for the largest event, to isolate the fault plane from the auxiliary plane. We then combine these mechanisms with results from previous studies of earthquake source and GPS geodetic velocity vectors and the GPS-derived strain field to build a kinematic model for this region. The depth distribution of the earthquakes reveals that they occur in the lower crust of the underthrusting Indian Plate. The oblique-thrust and thrust events are the result of compressive stresses in the inner arc of the flexed Indian Plate. The oblique convergence of the Indian Plate with respect to Tibet and the slab pull force from the subduction of the Indian Plate beneath Burma combined together are responsible for the strike-slip earthquakes. The region north of the Dauki Fault in the vicinity of the Kopili Fault Zone deforms through dextral strike-slip faulting and anti-clockwise rotation of blocks along NW-SE trending transverse structures. The transitional crust of the Bengal Basin has several NE-SW trending paleorifts which manifest sinistral strike-slip motion and clockwise rotation. The GPS velocity vectors and the strain field indicate that throughout most of the region north of the Dauki Fault there is a strong coupling between the surface deformation and the earthquake faulting whereas towards the south in some areas the coupling is weaker. The strike-slip events in the Indo-Burman Ranges probably occur due to a complex interplay between the trench-normal slab pull forces and lateral shear forces set up by the strike parallel components of the interplate coupling resistance and the mantle drag forces.
Meeting clean air targets could reduce the burden of hypertension among women of reproductive age in India
Authors: Singh Taruna , Dey Sagnik , Roy Ambuj , Ghosh Santu , Chaudhary Ekta
Published: March 2024

Objective: Air pollution is a prominent cardiovascular risk factor globally and poses a significant concern in low- and middle-income countries. This study shows the association between hypertension among women of reproductive age (WRA, 15–49 years) and exposure to PM2.5, a key pollutant. The aim of this study is to bridge the gap in epidemiological evidence, particularly within the context of India's hypertensive demographic. Aligned with Sustainable Development Goal (SDG) 3 which promotes good health and well being.Materials and Methodology: Utilizing data from the National Family Health Survey-5 (NFHS-5) and satellite-driven PM2.5 exposure, we examined the links between hypertension and PM2.5 constituents. Logistic regression, adjusted for socioeconomic indicators, including age, smoking, residence, education, and cooking fuel. Multiplicative interactions explored the moderating effects of variables such as smoking,BMI, and residence on PM2.5.Results: The adjusted odds ratio for hypertension increased by 1.05 (95% CI: 1.04–1.06) per 10 μg/m³ rise in ambient PM2.5, derived from satellite and MERRA-2 reanalysis (OR 1.04, 95% CI: 1.01-1.09). Notably, smokers exhibited a higher risk (OR 1.11, 95% CI: 1.10–1.16) compared to non-smokers (OR 1.05, 95% CI: 1.04–1.06). The economically vulnerable showed increased susceptibility (OR 1.07, 95% CI: 1.06–1.08). Dust and black carbon displayed stronger associations with hypertension (ORs 1.27 and 1.21, respectively). District-scale analysis suggested a potential 2.42% reduction if districts meet NCAP air quality targets, and a 4.21% reduction in prevalence of hypertension if WHO guidelines are met.Conclusion: Addressing SDG 3, the study emphasizes a positive association between PM2.5 exposure and hypertension in WRA, shedding light on critical health challenges in developing countries. Dust and black carbon emerge as key contributors, emphasizing the need for targeted interventions. Achieving air quality targets and stricter adherence to WHO guidelines could substantially reduce hypertension prevalence, showcasing the study's relevance to global health and well-being goals. From the perspective of the Indian Hypertension Control Initiative, emphasizing the potential impact of policy interventions in mitigating cardiovascular risks associated with air pollution in India.
Simulation of Regional Secondary Organic Aerosol Formation From Monocyclic Aromatic Hydrocarbons using a Near-Explicit Chemical Mechanism Constrained by Chamber Experiments 
Authors: Li Jingyi , Lu Hutao , Huang Qi , Ying Qi , Qin Momei , Hu Jianlin
Published: March 2024

The formation of secondary organic aerosols (SOA) is inextricably linked to the photo-oxidation of aromatic hydrocarbons. However, models still exhibit biases in representing the mass and chemical composition of SOA. We implemented a box model coupled with a near-explicit photochemical mechanism, the Master Chemical Mechanism (MCMv3.3.1) to simulate a series of chamber studies and access model biases in simulating SOA from representative aromatic hydrocarbons. The box model underpredicted SOA yields of toluene and xylenes by 4.7–100%, which could be improved by adjusting the saturation vapor pressure (SVP) of their oxidation products. After updating the SVP values, the mass concentration of TX SOA in the Yangtze River Delta region during summer was doubled, and there was also an approximated 3% enhancement in the total SOA. In comparison to a lumped mechanism used for simulating TX SOA, MCM predicted similar mass concentrations but exhibited different volatility distributions and oxidation states.
Anthropogenic Influences on the Extremely Dry and Hot Summer of 2020 in Southern China and Projected Changes in the Likelihood of the Event 
Authors: Wang Kaixi , Zheng Zhiyuan
Published: March 2024

During summer 2020, Southern China experienced an extremely dry and hot summer, which was identified as one of the top ten domestic weather and climate extreme events in 2020 by China Meteorological Administration. Summer mean precipitation, surface air temperature (TAS), and number of hot days (NHD) were about 25% dryer, 1.5℃ warmer, and 11 days larger than the 1981–2010 normal. These are the 4th largest precipitation deficit, the highest TAS, and the 2nd highest NHD in the 1961–2020 record. The large-scale circulation anomalies over the West Pacific increased the likelihood of these extremely event. Anthropogenic influences on this event were investigated using 525-member ensembles of the atmosphere-only HadGEM3-GA6 model and the multi-model ensembles from the Coupled Model Intercomparison Project Phase 6 (CMIP6). Anthropogenic forcings doubled (increased by 11%) the probability of precipitation deficits, and increased occurrence more than  times for both TAS anomaly (1.25 probability higher) and NHD anomaly (300% probability higher) in HadGEM-GA6 (CMIP6). That means that the 2020-like TAS and NHD anomalies would not occur without anthropogenic forcings, and there is weak evidence that human influences decrease rainfall over Southern China. However, the precipitation deficit increased the likelihood of exceeding the observed thresholds for both TAS and NHD by about 17 (4) and 9 (11) times in HadGEM3-GA6 (CMIP6), respectively. Under SSP2-4.5 and SSP5-8.5 scenarios in the future, 2020-like hot but wet extreme events increase in magnitude and frequency, while the frequency of dry events declines.
Stress-induced ramiform karstic conduits along a bedding plane: insights from a coupled hydro-mechanical-chemical (HMC) model
Authors: Jiang Chuanyin , Wang Xiaoguang , Jourde Hervé
Published: March 2024

Bedding plane partitions are an important geological medium to guide cave passages during the early stages of karstification in limestone formations. However, how stress load affects karst genesis processes along the large rough fractures remains poorly understood. Here, we develop a novel coupled hydro-mechanical-chemical (HMC) model to improve the understanding of this complicated process. This model considers a two-way mechanical-chemical coupling where dissolution perturbs the contact-stress distribution, in return impacting the fracture dissolutional enlargement. A non-linear correlation between the local fracture stiffness and contact stress is further incorporated. We study a two-dimensional horizontal fracture surface embedded in a three-dimensional rock block subjected to vertical stress loading. Simulation results show that dissolution causes local stress reduction (mechanical weakening), simultaneously accompanied by stress concentration at its fringe. The competition between dissolution-induced aperture enlargement and compaction-induced closure significantly retards the dissolution evolution. Without mechanical effect, linear dissolution fingering exhibits. As the applied stress increases, the secondary karstic conduits become more pronounced and a ramiform dissolution fingering featuring branching and winding is induced. Our results also provide important implications for understanding other engineering applications such as geothermal development and carbonate acidification.