bluuebunny/crossref_metadata_2025 huggingface dataset:
How do climate models represent wind resources in Southern Africa and predict their future changes?
Authors: Tang Chao , Morel Béatrice
Published: March 2024

As intermittent meteorological resources become increasingly vital in our energy system, it is crucial to better understand how a changing climate may affect weather variability and, in turn, influence future wind energy production. This study evaluates the performance of climate models in reproducing wind resources over Southern Africa (SA), and in assessing potential impacts of climate change. An ensemble of climate simulations is evaluated over SA, which includes simulations from three Regional Climate Models (RCM; i.e., CCLM4, RegCM4, and REMO2009) that participated in the Coordinated Regional Downscaling Experiment program over Africa (CORDEX-Africa) at a horizontal resolution of approximately 25 km, and the coarser-resolution ones from their four driving General Circulation Models (GCMs; i.e., HadGEM2-ES, MPI-ESM-LR, MPI-ESM-MR, and NorESM1-M) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The simulated wind is first compared to the reference datasets, derived from ground-based measurements and reanalyses, during 2000-2023 at 3-hour intervals, covering both surface and hub-height (100 m) levels. The performances of both RCMs and GCMs are quantified and compared in terms of their representation of wind resource characteristics, including the mean wind speed and its spatio-temporal variability at hourly-to-annual timescales. Then wind energy potential and capacity factors are also derived for the wind resource assessment in SA, where direct observational data is limited. Finally, the potential impact of climate change on the 100-meter wind energy potential in SA is assessed based on this ensemble of climate projections, up to 2099, under the RCP2.6 and RCP8.5 scenarios. This study helps to understand the performance difference between regional and global models in simulating wind resources and provides insight into how changing climate conditions might affect wind energy production over the long term in SA.
Stratigraphic and tectonic setting of the Rus Formation at Jebel Hafeet, UAE.
Authors: Decarlis Alessandro , Hennhöfer Dominik , Arboit Francesco , Ceriani Andrea
Published: March 2024

The Rus Formation consists of a succession of carbonate rocks deposited in the Southeastern Arabian foreland system during the Paleocene-Ypresian. Throughout the UAE, the Rus Formation is commonly restricted to the subsurface of the Abu Dhabi Emirate territory, with the exception near the western front of the Hajar Mountains close to Al Ain city. At this location, the Rus Formation is exposed and forms the core of the Jebel Hafeet km-scale anticline fold. This large-scale exposure allowed us to study its stratigraphic and tectonic evolution from deposition to the present-day tectonic framework. Lithostratigraphic and facies analyses of the outcropping portion of the Rus Formation at Jebel Hafeet identified a succession of approximately 150 m of limestones and dolostones characterized by three main depositional facies:platform facies, characterized by thick to massive carbonate beds with abundant shallow-water bioclasts;
ramp facies, showing evidence for syn-depositional instability, with mass flows and collapse structures;
ramp-basin facies, characterized by thin beds with marked downlapping geometries.
Thus, the studied succession forms a complete platform-to-foreland basin transition that is well-exposed along the hinge of the fold structure. The base of the Rus Formation is concealed beneath the widespread quaternary cover, whereas the top of the Rus consists of unconformable stratigraphic contact with the Dammam Formation.During the Early Cenozoic, the depositional environment of the Rus Formation was probably subjected to far-field stress due to the migration of the foreland depocenter in response to the obduction of the ophiolite slabs onto the Arabian continental margin successions. Structural analyses of deformation features such as faults and folds and geochronological/geochemical analysis of the correlated calcite veins (U-Pb on calcite) within the Rus Formation revealed that compressive tectonics generated the main folding event and drove subsequent exhumation from c. 20 to 2 Ma. Thus, these new data suggest that the deformation and uplift of Jebel Hafeet succession occurred in the context of post-Oligocene tectonics simultaneously with the Zagros collision but were likely developed along a strike-slip system accommodating the push of the Eastern Makran Belt.
Situation-Dependent Localization for All-Sky Satellite Observations
Authors: Necker Tobias , Honda Takumi , Griewank Philipp , Miyoshi Takemasa , Weissmann Martin
Published: March 2024

This study aims to improve the localization and assimilation of satellite observations in the visible and infrared spectral ranges to enhance predictions of clouds and convective processes. Understanding correlation structures between satellite observations and atmospheric state variables is crucial for successful data assimilation. We focus on examining vertical ensemble-based correlations from Himawari-8 channels (VIS0.64 or IR7.35) and tackle the challenge of vertical observation-space localization. Traditional distance-based localization methods are often suboptimal due to the multi-layered origin of observed radiation. We present empirical optimal localization (EOL) functions derived from a 1000-member ensemble convective-scale simulation to address this issue. Our research highlights the need for channel-specific and variable-specific localization strategies, emphasized by our analysis of two summer case studies that exhibit substantial situational variability in correlation structures, especially in the visible spectral range. Further, we explore various predictors for formulating dynamic, situation-specific vertical localization strategies, offering insights into their effectiveness and potential for advancing convective-scale satellite data assimilation.
Analogue and numerical modelling of rock deformation due to subsurface compressed gas storage 
Authors: Johnson James , Kiss Daniel , van Noort Reinier , Yarushina Viktoriya
Published: March 2024

Storage of compressed gases in lined rock caverns (LRC) has been proposed in order to buffer the peaks of energy intake/output for industrial/renewable systems. LRCs consist of a thin (1-2 cm) steel liner to ensure gas tightness, surrounded by a concrete layer (0.5-2 m) to transmit stresses to the host rock which acts as a pressure vessel. Advantages of storage in such underground LRCs when compared to storage in tanks on the surface or on the seabed include (1) increased safety, and potentially (2) increased storage capacity.Pilot studies exploring the feasibility for LRC storage have been carried out showing the potential for the technology (e.g. Grängesberg, Sweden​; Skallen, Sweden; ANGAS, Japan). All three test facilities demonstrated that it is possible to reach a gas pressure that is at least 20 times larger than the lithostatic pressure without compromising the integrity of the LRC. While these pilot tests are valuable for demonstrating the potential of the LRC technology, it is not possible to extrapolate safe operating conditions for future scenarios (e.g. shallower depths, different rock types). As a result, widespread adoption of LRC storage is hindered by uncertainty. Our focus is operating pressure, which scales roughly with storage capacity, and thus has a direct impact on LRC profitability.In this study we will present results of analogue and numerical models. We focus on brittle deformation in the host rock due to the load exerted by a pressurized cavity. Our specific goal is to determine the extent of safely acceptable brittle deformation, and to identify useful indicators of storage integrity to be monitored during initial pressurization tests and continuous operation. Our analogue modelling of this system identifies key parameters that influence the potential success of these projects including (1) proximity to surface, (2) strength of the host rock, (3) mechanical anisotropy, (4) injection rate and amount, and (5) type of liner(s) applied. For the analogue modelling we use gelatin to represent a shallow competent host rock (e.g. granite, gneiss). A hole placed centrally on one side of the cell allows for the injection of compressed air. Utilizing a balloon placed within the hole, the compressed air acts on the liner until the stress applied by the forced air results in visible strain (i.e. fracturing). For the numerical modelling we use a 2D, visco-elasto-plastic, finite difference, hydro-mechanical code utilizing a pseudo-transient solver running on GPUs. The main goal is to cross-validate the results of the two independent methods, and to provide a straightforward way to extrapolate from laboratory simulation to real world conditions.
Local biophysical impacts of idealized land-cover and land management changes on climate extremes in the semi-arid West African Savannas
Authors: Sy Souleymane , Bliefernicht Jan , Arnault Joel , Olsesegun Christiana , Fersch Benjamin , Spangenberg Ines , Guug Samuel , Yahaya Seydou Abdel Nassirou , Oussou Francis , Waongo Moussa , Sawadogo Windmanagda , Rummler Thomas , Neidl Frank , Laux Patrick , Quesada Benjamin , Kunstmann Harlad
Published: March 2024

The West African savannas region is currently undergoing extensive agricultural intensification due to rapid population growth. Those anthropogenic land cover changes (LCC) can have significant impacts at regional and seasonal scales but also on extreme weather events to which human, natural and economical systems are highly vulnerable. However, the effects of LCC on extreme events remain either largely unexplored at regional/local scale and/or without consensus. To address this issue, we investigate the biophysical impacts of idealized land use and land management changes (LCLMCs) scenarios on climate extremes in the semi-arid West African Savannas region. This analysis is conducted using high-resolution land-cover change experiments (at 3 km) covering the period from 2011 to 2023. These experiments utilize the fully coupled WRF-Hydro system, which incorporates surface and subsurface lateral flow while describing the vegetation dynamically. The local effects of idealized LCLMCs scenarios are derived through a comparison of multiple land-use and afforestation scenario-based simulations, reflecting a specific LCC transition, occurring over the Sudan Savanna of Burkina Faso and Ghana.Analyzing 20 extreme weather indices, we find, on average, that LCC robustly lessens regional extreme rainfall by 8% for the number of wet days (R1mm) and by 7% for the heavy rainfall (R10mm) more than mean rainfall conditions (up to 2 times more). LCC can impact regional rainfall extremes 4 times more than temperature extremes on average and intensifies dry days. Afforestation options, such as the conversion of grassland to evergreen broadleaf forest or evergreen needleleaf forest, tend to mitigate the biophysical LCC-induced warming effect and lower the associated occurrence of temperature extreme events. Conversely, opposite effects can be observed under savannas-based afforestation options, likely due to their associated large sensible heat fluxes compared to grassland and cropland. The study investigates the underlying biophysical drivers behind these opposing effects.We stress here that fully coupled modeling frameworks incorporating all aspects of land-use change and local positive feedback between the terrestrial hydrological system and the overlying atmosphere are needed to better evaluate land-based mitigation and adaptation strategies.
The impact of land use on the adsorption of fluoroquinolone antibiotics: a study on bulk soils and organic matter pools
Authors: Vancsik Anna , Szabó Lili , Bauer László , Király Csilla , Pirger Zsolt , Kondor Attila Csaba , Jakab Gergely , Szalai Zoltán
Published: March 2024

Fluoroquinolone antibiotics are widely used in animal husbandry and human medicine and are therefore released into environmental systems in significant quantities. Because of its targeted antibacterial action, it directly disrupts the soil microbial ecosystem and alters soil carbon fixation. In order to maintain soil microbial communities and prevent groundwater pollution, it is essential to know what physicochemical properties a soil must have to be safe for sewage sludge application and irrigation with treated wastewater. To understand the effects of land use on the adsorption properties of Luvisols, three different land use areas (arable land, grassland, and forest) and two organic matter (OM) pools (fast and slow) were investigated. The soils were separated to a > 53 µm fraction related to the fast OM pool and a < 53 µm fraction containing the slow OM pool, to investigate the physicochemical properties that affect adsorption capacity. Ciprofloxacin, norfloxacin, and ofloxacin were chosen for adsorption experiments because they are widely detected in environmental systems. The effect of land use on adsorption was only observed in the slow pool in the ascending order of arable land, grassland, and forest. Principal component analysis showed that OM content and composition influenced adsorption in the slow pool. However, the adsorption of bulk soils and fast pools is primarily controlled by the physical soil properties rather than by soil OM. These findings indicate that the OM composition of the < 53 µm fraction with the slow pool can determine the adsorption of bulk soils. However, in the present study, this did not affect the adsorption of bulk soils because either 1) the ratio of the slow pool was small, but its adsorption capacity was high, as in the forest, or 2) the ratio of the slow pool was large but its adsorption capacity was low due to its OM composition, as in arable land and grassland. Therefore, irrigation with treated wastewater and sludge discharged on agricultural lands is more likely to leach pollutants into groundwater. Consideration should be given to the disposal of sludge in an area with a high aliphatic soil OM content, where the slow pool rate is high.This research was supported by the National Research, Development, and Innovation Office (NKFIH), Hungary (project identification number: 2020–1.1.2-PIACI-KFI-2021-00309; 2021–1.2.4-TÉT-2021-00029, and K-142865). Project no. KDP-1015196 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. This study has also been supported by the Doctoral Excellence Program (DKOP-23) of the Ministry for Culture and Innovation, Hungary, from the source of the National Research, Development and Innovation Fund.
Surface deformation and Source Parameters of 2023 Hatay Earthquake inferred from the InSAR Data Analysis
Authors: Ercan Merve , Kaya Eken Tülay , Zoroğlu Çağkan Serhun , Havazlı Emre , Özener Haluk
Published: March 2024

Abstract Tectonic features of Türkiye are mainly controlled by the relative northward movements of the Arabian and subducting African plates with respect to the Anatolian and Eurasian plates. Resultant extensional and collisional tectonics lead to a westward material extrusion accommodated along the right- and left-lateral strike-slip North Anatolian and East Anatolian Fault Zones (NAFZ and EAFZ), respectively. This lateral motion continues southward along the Dead Sea Fault Zone (DSFZ) at the southeastern of Türkiye. February 20, 2023, Mw 6.3 Hatay Earthquake occurred two weeks after the seismic energy release of the February 6, 2023, Kahramanmaraş earthquakes at the intersection of EAFZ, DSFZ, and the onshore extension of the Cyprus Arc. The N-S trending DSFZ starts from the south of the EAFZ and continues through Syria, Lebanon, and Israel. Although the broken segment in Hatay is not as active as the northern segments of the EAFZ, it has accumulated strain leading to significant seismic activity in the past in this region, i.e., the 1872 M7.2 earthquake occurred on the Karasu Fault. 2023 Kahramanmaraş and Hatay earthquakes caused severe damage in Hatay and the surrounding area. To determine the co-seismic deformation during the February 20, 2023, Hatay Earthquake, we applied the Interferometric Synthetic Aperture Radar (InSAR) technique on the Sentinel-1 data. Ascending and descending track SAR images before and after the Kahramanmaraş and Hatay earthquakes were analyzed using the TopsApp module of the InSAR Scientific Computing Environment (ISCE) software to obtain Interferograms of co-seismic deformation in and around Hatay region. Finally, we investigated source parameters by performing an inversion on geodetic constraints considering the Okada elastic dislocation model.
Ecosystem mapping with remote sensing images and ground observations
Authors: Zermatten Valerie , Castillo-Navarro Javiera , Marcos Diego , Tuia Devis
Published: March 2024

Natural ecosystem maps are a fundamental tool for describing natural habitats. They are used when analysing ecological networks, for studying ecological connectivity, for conservation planning or for the management of ecosystem services. While remote sensing information is commonly employed for mapping land cover, accurate ecosystem maps require going beyond the classification of the physical surface of the land and attempting to distinguish different communities of living beings. New research directions for ecosystem classification leverage species observations created by citizen scientists on social media or crowd-sourcing platforms, profiting from their extensive spatial and temporal coverage and their low acquisition cost.In this work, we make complimentary use of crowd-sourced data with remote sensing imagery to produce ecosystem maps in alpine areas. Our study area covers the state of Valais, a territory of about 5, 000km2 in southwestern Switzerland. We retrieve nearly 3 million species observations from the Global Biodiversity Information Facility (GBIF) database that includes governmental, crowd-sourced and scientific observations. We combine the species data with high-resolution aerial remote sensing imagery provided by the Swiss Federal Office of Topography swisstopo. As reference ecosystem maps, we follow the European Nature Information System (EUNIS) at a 100m scale. To solve the task of classifying ecosystems, we propose a multi-modal data fusion approach based on a multi-modal transformer architecture. Such a model can handle redundant and complementary information coming from different data sources and provide an explicit and interpretable decision through the visualisation of its attention scores. Through our preliminary experiments, we observed that the unequal distribution of samples between the classes and also the sampling biases negatively impacted the performance of our approach. We are working towards a more informative inclusion of species observation and a more balanced learning of each ecosystem type.
CarboKitten.jl, an Open Source simulator for Carbonate Platform formation in Julia
Authors: Hidding Johan , Liu Xianyi , Burgess Peter , Jarochowska Emilia
Published: March 2024

Carbonate Platforms form an important source of information on the past evolution of species as well as the climate conditions they lived in. However, stratigraphic records are often considered unreliable tracers of evolution, since they contain many gaps.These gaps are often on a time scale too short to measure, but may significantly affect further studies of biodiversity and climate change. This is why we use forward modelling to estimate the statistics of gap distributions under a wide variety of environmental parameters. Forward modelling can be used to test hypotheses at time scales that are not available for experimentation. The dominant driver for generating different stratigraphic architectures is the input sea-level curve, balancing periodic (Milankovich), stochastic and subsidence only effects. Added to that are varying degrees self-organisation, sediment transport and subarial erosion.The basis of our model is sediment production following the model by Bosscher and Schlager (1992), with biological self-organisation modeled after the cellular automaton approach (CarboCAT) by Burgess (2013) and a sediment transport model inspired on Warrlich (2000).CarboKitten is fully Open Source, written in Julia, aiming for performance, modularity and ease of use. We will show preliminary results produced by CarboKitten and also explain how they are generated.
3-dimensional winds and impacts of the typhoon observed in the MLT region using the Chinese multistatic meteor radar network
Authors: Zeng Jie , Stober Gunter , Yi Wen , Xue Xianghui , Dou Xiankang
Published: March 2024

We present the first continuous observations of the three-dimensional winds in the mesosphere and lower thermosphere (MLT) of the northern hemisphere midlatitudes using the composite data from the first multistatic meteor radar network in China. Our continuous observations started in 2022. In the summer of 2023, typhoon Doksuri passed through China and resulted in intense rainfalls. To reveal the impact of the typhoon on the MLT region, we focus on the variability in the three-dimensional wind fields. The horizontal winds are retrieved using an improved Volume Velocity Processing (VVP) with coordinate transformation and non-linear constraints to minimize errors, and the vertical winds are retrieved from the horizontal divergence with magnitudes of less than 1m/s. We found that on the day when the typhoon passed through our meteor radar network, the horizontal winds strengthened southwest and contained small-scale waves, and the vertical winds showed no significant change.
Vertical Land Motion Detection Using Satellite Altimetry Data at the Hadera Tide Gauge Station
Authors: Murshan Milaa , Devaraju Balaji , Balasubramanian Nagarajan , Dikshit Onkar
Published: March 2024

Vertical Land Motion (VLM) estimation involves various methods such as Global Navigation Satellite Systems (GNSS), Very Long Baseline Interferometry (VLBI), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and Satellite Laser Ranging (SLR). However, satellite altimetry presents an alternative approach for estimating VLM independently. This study compares altimetry-based VLM estimates with those obtained from Tide Gauge (TG) devices. The VLM is determined by calculating the difference between the linear trends of sea-level time series derived from altimetry-based data Instantaneous Sea Surface Height (ISSH) and TG data. Additionally, VLM can be estimated by comparing the linear trends of altimetry-based Sea Level Anomalies (SLA) and TG SLA time series. To estimate VLM, absolute ISSH measurements from satellite altimetry, unaffected by the Earth's crust, are contrasted with relative sea level measurements recorded by TG stations with respect to a fixed land point. By differentiating and aligning temporal pairs of TG and altimetry data, only the linear trend remains, representing the vertical displacement of the TG station relative to the reference surface. Removing satellite altimetry instrumentation drifts enables the extraction of VLM from the difference in linear trends. The VLM estimate obtained for the Hadera TG station, covering 1992-2016, shows a positive trend of 0.24 ± 0.07 mm/year. This finding aligns with GNSS-based VLM estimations at the same station, indicating land uplifting in the region. Consequently, the study suggests that there is no immediate concern about the rise of sea level. These findings enhance our understanding of regional geodetic processes and their implications for assessing sea level changes. By providing valuable information on VLM estimation, this research contributes to our knowledge of vertical displacement on land and its significance for future studies.
Model Calibration and discharge simulations during extreme drought events for the Rhine River Basin using WRF-Hydro.
Authors: Campoverde MSc. Andrea , Ehret PD. Dr.Uwe , Ludwig Dr.Patrick , Pinto Prof. Dr. Joaquim
Published: March 2024

Recent drought events, leading to low water levels, have significantly affected navigation through the Rhine River and the transportation of goods. It has become imperative to analyze the conditions in which these events occurs to establish actions to prevent monetary losses. The main focus of this study is to test how well the hydrological model WRF-Hydro can capture extremely low water levels in the Rhine River basin. Using the meteorological reanalysis dataset ERA5 as forcing data for the model, we simulate the streamflow from January 2016 to December 2018, which includes the recent drought event in the Summer of 2018. Within the model, the calibration of various parameters allows the evaluation of the streamflow from WRF-Hydro to be contrasted with the daily observed values. The parameters influencing the amount of water routed across the basin are generally constant throughout the domain. Land use cover and terrain slope were used to create spatially distributed parameter values, avoiding the calibration process of testing a range of values and, therefore, reducing computational time. These promising results enables us to analyze recent and future drought events under different climate conditions.
Policy matrices – A tool for reviewing the effectiveness of risk management policies across scales and disciplines. 
Authors: Durrant Louis , Teller Jacques , Santangelo Angela , Baldassarre Benedetta
Published: March 2024

Policies are a deliberate system that defines action and guides short-term decisions in pursuing a goal. Policy is a fundamental instrument of governance which is extensively used worldwide. However, not all policies are created equally. Contemporary literature is littered with examples of policy failures, and a large research emphasis is dedicated to co-creating ‘good’ policy. This challenge of developing good policy is exacerbated when we consider the rapidly evolving risks related to climate change. The evolving risks can make it difficult to define valid policy goals over the longer term. Furthermore, stakeholders are increasingly needed across policy and practice to overcome siloed working and co-create transdisciplinary risk management policies, considering both long-term strategic objectives and short- to medium-term operational solutions. Risk management policy instruments are relevant across spatial scales and engage with policies from other disciplines (urban planning, heritage conservation, environmental management). The article presents an innovative tool called the policy matrix to address challenges faced by policy experts. The policy matrix capitalises upon the co-creative research of the Organigraphs technique defined by Durrant et al. (2021) to co-create disaster risk management governance maps.  The article compares two policy matrices developed as part of a Horizon 2020-funded project called SHELTER. In its simplest form, a policy matrix arranges risk management policy instruments around an issue depending on their scale of implementation and disciplinary lens. This allows stakeholders to see all the policy instruments considered relevant to some specific issues. It can further provide stakeholders a robust platform to critique those policies.  By way of example, providing them with a tool to clearly “measure” the links between these policies, to identify policy gaps in thematic/operationalisation, or, from a practical perspective, to provide a tool for experts to review the level of participation in the design of these policies or the effectiveness of these policies in practice. 
Drivers of intra‐seasonal δ13C signal in tree‐rings of Pinus sylvestris as indicated by compound‐specific and laser ablation isotope analysis
Authors: Rinne-Garmston Katja , Tang Yu , Sahlstedt Elina , Adamczyk Bartosz , Saurer Matthias , Salmon Yann , del Rosario Domínguez Carrasco Maria , Hölttä Teemu , Lehmann Marco , Mo Lan , Young Giles
Published: March 2024

Carbon isotope composition of tree‐ring (δ13CRing) is a commonly used proxy for environmental change and ecophysiology. δ13CRing reconstructions are based on a solid knowledge of isotope fractionations during formation of primary photosynthates (δ13CP), such as sucrose. However, δ13CRing is not merely a record of δ13CP. Isotope fractionation processes, which are not yet fully understood, modify δ13CP during sucrose transport. We traced, how the environmental intra‐seasonal δ13CP signal changes from leaves to phloem, tree‐ring and roots, for 7 year old Pinus sylvestris, using δ13C analysis ofindividual carbohydrates, δ13CRing laser ablation, leaf gas exchange and enzyme activity measurements. The intra‐seasonal δ13CP dynamics was clearly reflected by δ13CRing, suggesting negligible impact of reserve use on δ13CRing. However, δ13CP became increasingly 13C‐enriched during down‐stem transport, probably due to post‐photosynthetic fractionations such as sink organ catabolism. In contrast, δ13C of water‐soluble carbohydrates, analysed for the same extracts, did not reflect the same isotope dynamics and fractionations as δ13CP, but recorded intra‐seasonal δ13CP variability. The impact of environmental signals on δ13CRing, and the 0.5 and 1.7‰ depletion in photosynthates compared ring organic matter and tree‐ring cellulose, respectively, are useful pieces of information for studies exploiting δ13CRing.
Capturing the Variability of the Nocturnal Boundary Layer through Localized Perturbation Modeling
Authors: Kaiser Amandine , Vercauteren Nikki , Krumscheid Sebastian
Published: March 2024

Numerical weather prediction and climate models encounter challenges in accurately representing flow regimes in the stably stratified atmospheric boundary layer and the transitions between them. This leads to an inadequate depiction of regime occupation statistics and, therefore, to biases in forecasts of near-surface temperature. To explore inherent uncertainties in modeling regime transitions, the response of the near-surface temperature inversion to transient small-scale phenomena is analyzed based on a stochastic modeling approach. A sensitivity analysis is conducted by augmenting a single-column model for the atmospheric boundary layer with deterministic perturbations accounting for small-scale fluctuations in the wind and temperature dynamics and with a stochastic stability function to account for turbulent bursts. The model is a tool to systematically investigate what types of unsteady flow features may trigger abrupt transitions in the mean boundary layer state. Previous research showed that incorporating enhanced mixing, a common practice in numerical weather prediction models, blurs the two regime characteristics of the stably stratified atmospheric boundary layer. Simulating intermittent turbulence through a stochastic stability function is shown to provide a potential workaround for this issue. Including key uncertainty in models could lead to a better statistical representation of the regimes in long-term climate simulation. 
Valorization of agricultural residues through its transformation into sustainable filters for water treatment
Authors: Sánchez-Martín Águeda M. , Pérez Dalí Sara , Undabeytia López Tomás , Marquez Moreno Jorge , Dieguez-Alonso Alba , Behrendt Frank , Almuiña-Villar Germán , De la Rosa José María
Published: March 2024

Finding a sustainable solution to the increasing amount of organic waste generated, and reducing air, soil and water pollution are two most pressing environmental issues today. In both problems, agriculture plays a crucial role. Within this context, this study aims to valorize abundant agricultural waste via its transformation into activated carbon (AC), useful for the removal of emerging organic contaminants (EOCs) in water.Thus, rice husk (RH) and almond shell (AS) were characterized, pyrolyzed and tested as feedstock for ACs to be used as water filters. In addition, chemical (with KOH) and physical activation (with water vapor) of the pyrolyzed materials were performed.The elemental composition and physical properties were suitable in both cases (alkaline pH, high water retention capacity, Carbon content and Iodine index). The specific surface area (SSA-BET) increased significantly to values 600 m2 gr-1 on the ACs produced from physically activated and pyrolyzed RH.Furthermore, adsorption tests of anti-inflammatory and antibiotic compounds in water showed that ACs produced from RH were able to adsorb up to 100 % of the these persistent EOPs, performing similarly to commercial AC. Acknowledgements:This study received financial support in the framework of the Project RICERES4CHANGE (grant TED2021-130964B-I00), by the Spanish Agency of Research (MCIN/AEI/10.13039/501100011033) and the European Union (Next Generation EU/PRTR funding).A.M. Sánchez-Martín thanks The Spanish Ministry of Science and Innovation (MICIN) for her contract as Technical Support Personnel (PTA2021-020000-I). M. Arenas is thanked for this technical and analytical support.
Water level regimes, forest composition, and forest functioning in floodplain forests in southeastern Brazil
Authors: Meyer Oliveira Aline , Gianasi Fernanda , Vieira Pompeu Patrícia , Manoel dos Santos Rubens , van Meerveld Ilja
Published: March 2024

Floodplain forests are unique ecosystems at the interface between rivers and terrestrial environments. They provide important ecosystem services, such as biodiversity conservation and flood control. However, they are also one of the most threatened ecosystems. Vegetation composition in floodplain forests depends on the flood regime, but there is a lack of knowledge on the relation between the water level regime and forest composition and functioning for the seasonally dry tropics. As a result, it is unclear how these forests will be impacted by climate change.In the WatForFun (“Water level regime and forest functioning in floodplain forests”) project, we brought together an interdisciplinary team of hydrologists and ecologists to better understand the relation between flood dynamics (e.g., flood frequency and duration) and tree species composition, phylogenetic diversity, functional diversity and taxonomic diversity. Fieldwork was conducted in six seasonally flooded forests in the state of Minas Gerais in southeastern Brazil. Three floodplains are located in the Rio Grande basin (Capivari, Jacaré, and Aiuruoca), and another three in the São Francisco basin (Jequitaí, Verde Grande, and Carinhanha). The floodplains encompass a gradient in climate, from humid subtropical to seasonal dry tropical. For each floodplain, we identified five geomorphological eco-units based on the vegetation composition: marginal levee, lower terrace, upper terrace, lower plain, and higher plain. We surveyed the vegetation at each site and installed groundwater wells and surface water level loggers to monitor the water level regime. We sampled xylem water, soil water, groundwater, surface water and precipitation to identify the sources for tree water uptake based on the stable isotopes of hydrogen and oxygen.The eco-units differ from each other with regards to vegetation composition, phylogenetic and taxonomic diversity, and in terms of flood duration and flood frequency. The terraces remained flooded for longer periods of time than the other eco-units. The flood duration for the levees differed for the two basins. The xylem water was more depleted during the wet season than during the dry season, suggesting that trees change water uptake strategies depending on water availability. These findings help us to better understand the relation between floods and vegetation composition and to predict the impacts of climate change on vegetation composition and diversity.  
Reconstructing South Pacific Convergence Zone precipitation over the past 60 ka using plant wax biomarkers
Authors: Peaple Mark , Inglis Gordan , Langdon Pete , Joshi Manoj , Skinner Daniel , Mattews Adrian , Osborn Timothy , Roberts William , Sear David
Published: March 2024

Hydroclimate in the tropical South Pacific is dominated by the South Pacific Convergence Zone (SPCZ), a region of low-level atmospheric convergence responsible for providing fresh water to 11 million people. The SPCZ is known to change in orientation and intensity in response to interannual climate phenomena, including El Niño Southern Oscillation (ENSO) and the interdecadal Pacific Oscillation (IPO), principally through modulation of trade wind strength (i.e., Walker circulation strength), and the resultant moisture inflow. Understanding how the orientation and intensity of the SPCZ changed under past climate states is important to predict future SPCZ changes, currently poorly represented in existing GCM’s. However, our knowledge of the dynamics of the SPCZ beyond the last 1000 years is limited by a lack of proxy archives and a large spread in climate model ensembles. We present a 60 ka plant wax record of paleoprecipitation collected from a peat sediment core from the island of Nuku Hiva, French Polynesia, located in the northeastern margin of the SPCZ. We demonstrate that Nuku Hiva was drier during the last glacial maximum (LGM) and wetter during the early Holocene compared to modern conditions. This indicates that the SPCZ was located further to the south during the LGM and further to the north during the early Holocene. We find a strong correlation between our SPCZ precipitation record and foraminifera based reconstructions of western Pacific warm pool thermocline depth. Given that both modern western Pacific thermocline depth and Nuku Hiva precipitation are influenced by easterly trade wind speed, we deduce that trade wind speeds were likely lower during the LGM and higher during the early Holocene, highlighting the long term dependence of SPCZ orientation on Walker circulation strength. This study, will help constrain future predictions of SPCZ precipitation change.
Spatiotemporal variability of turbulent fluxes over snow in mountain regions 
Authors: Engbers Rainette , González-Herrero Sergi , Wever Nander , Gerber Franziska , Lehning Michael
Published: March 2024

Turbulent exchange of heat and moisture plays an important role in snow cover dynamics in mountain regions and governs the boundary layer dynamics. While these processes are subject to great spatiotemporal variability, particularly in complex terrain, virtually all measurements of heat, moisture and momentum fluxes are point observations. To quantify the spatial variability, and assess the representativeness of the observations, numerical modelling of the atmosphere and surface is a useful tool. Still, there is substantial uncertainty in the accuracy of how surface models capture this spatial variability, particularly in complex terrain with large spatial variability on small scales. These uncertainties can be partially attributed to (1) the use of Monin-Obukhov similarity theory (MOST) which has limitations in complex terrain due to the role of advection and (2) the errors in representing near-surface atmospheric gradients in the simulations. In this study, we analyse sources of errors in representing energy exchange over snow in mountain regions and look specifically at the spatiotemporal variability during different meteorological events in the region of Davos, Switzerland. To verify common modelling approaches with observations, we use model predictions of turbulent fluxes from CRYOWRF, the atmospheric model WRF coupled to the surface model SNOWPACK. The fluxes at different resolutions are compared to turbulent fluxes measured using the Eddy Covariance method (EC) and calculated with MOST. This model validation is done for different meteorological events representative of the local climate. Preliminary results indicate that the fluxes are highly spatially variable, being an order of magnitude higher on the leeside than on the windward side of a mountain ridge. This indicates that local heat fluxes are not representative of the whole mountain area, which has implications for the calculation of snow melt, sublimation and accumulation across mountainous terrain. The resolution of the model also plays a large role in representing the fluxes as the modelled fluxes differ greatly depending on the resolution. Our results quantify to what extent snow-atmosphere interactions and their spatial variability are correctly represented in state-of-the-art numerical weather and snow models. 

 
Cascading effects of shrub encroachment in sub-alpine grasslands from a trait-based perspective
Authors: Laorden-Camacho Lucía , Tello-García Elena , Grigulis Karl , Colace Marie-Pascale , Gallet Christiane , Peintner Ursula , Tappeiner Ulrike , Leitinger Georg , Lavorel Sandra
Published: March 2024

In the context of climate change, shrub encroachment is expected to advance in temperature-sensitive ecosystems such as arctic and alpine grasslands. In mountain regions, shrub encroachment is further triggered by grassland management changes (i.e., land abandonment or extensification). Shrub encroachment is expected to significantly impact ecosystem properties and functions like carbon stocks in both aboveground and belowground compartments, nutrient concentrations, and to slow down biogeochemical cycles. While studies of shrub encroachment processes and their effects on plant and soil functioning have increased our understanding of underpinning processes, there is still a lack of integrated studies and knowledge gaps on the interaction between plant-soil changes and their cascading effects. Our study focuses on understanding these effects on plant community traits and soil properties, and whether these changes are linear. We took herbaceous, shrub and soil samples along gradients of encroachment in sub-alpine grassland communities at two sites in the Alps: Lautaret (France) and the Stubai Valley (Austria). We used a trait-based approach to analyze hypothesized nonlinear functional changes in communities, using community-weighted means (CWM) to scale herbaceous and shrub functional traits and plant allometries. Structural equation models (SEM) support our hypothesis that changing CWM with increasing shrub biomass flows on to changes in soil properties. Dwarf shrub encroachment leads to more conservative and less nutrient-rich plant communities, resulting in an accumulation of recalcitrant organic matter and nutrient-poor soils. Nevertheless, contrary to our expectations, decreased nitrogen in plant communities along the encroachment gradient did not lead to decreased soil available nitrogen. Our results generally suggest it is possible to characterize shrub encroached ecosystems in the Alps using well-studied traits of the global plant economic spectrum, like nitrogen content or dry matter content. With these findings, we are confident that well-researched trait-based models are also applicable for dwarf shrubs, allowing to scale-up from plant traits to the delivery of ecosystem services. This research provides a novel understanding of shrub encroached ecosystems and is a first step in understanding the patterns and mechanisms underpinning their provision of ecosystem services.
Imaging deep subducted lithosphere beneath the Indian Ocean with seismic source array recordings
Authors: Thomas Christine , Heyn Björn Holger
Published: March 2024

The D" region, located just above the core-mantle boundary (CMB), is a geologically interesting region that has been imaged using both tomographic and reflection techniques. However, reflection studies often rely on array analysis techniques, and the lack of suitable seismic arrays in the oceans has left large areas of D" unmapped. One notable area, that is currently sparsely sampled, is beneath the Indian Ocean, where ancient subducted lithosphere has been imaged near the CMB in global tomography studies. We take advantage of the long-running history of five GEOSCOPE stations located in the western Indian Ocean and Antarctica, to investigate the possibility of using source arrays to detect P-wave reflections from the discontinuity above the D" layer. Despite restricting the selected earthquakes around Indonesia to a 120 km depth range and implementing several source normalization techniques, source-array stacks (i.e., source vespagrams) were difficult to interpret. We infer that this complication arises from differing earthquake depths, violating the plane wave assumption made when constructing these stacks. Therefore, we extend our method to a source-array scatter imaging method, which we call source migration, that does not rely on travel-times calculated for a plane wave. Using this technique in conjunction with source normalization, we found clear evidence for a D" P-wave reflector at four of the six GEOSCOPE stations considered in the study. The depth of the reflector for our imaged region varies between 190 km above the CMB beneath the Great Australian Bight and 220 to 270 km beneath the Indian Ocean west of Australia. Our determined depth in the northern portion of our study area is consistent with previous studies of D" depths using S-waves. We suggest that our D" reflections are the result of the previously imaged subducted lithosphere in the region and find that this lithosphere likely thins to the southeast. Additionally, our work more broadly indicates that the long-running history of single global seismic stations combined with source array techniques may be utilized to compliment and extend previous work imaging D" using conventional receiver-array techniques.
Identification of Two-Step Non-linear Interactions via Zonally Symmetric Waves during Major Sudden Stratospheric Warmings
Authors: Mitra Gourav , Guharay Amitava , Conte Fede , Chau Jorge
Published: March 2024

This study delved into atmospheric tides and their dynamics during two major boreal sudden stratospheric warmings (SSWs). Using meteor radar wind data, our investigation unveiled compelling indications of non-linear interactions between the semidiurnal solar tide and the quasi-20-day wave (Q20dw) in the high latitude mesosphere and lower thermosphere (MLT) during SSWs. Additionally, the diagnosis of zonal wavenumbers indicated potential non-linear interaction between the dominant semidiurnal migrating tide (SW2) and the zonally symmetric 20-day wave (20dw0) component, generating secondary waves. The study emphasized the significance of the non-linear interaction between the zonal wavenumber 2 component of the stationary planetary wave (SPW2) and the westward propagating 20-day wave (20dwW2) in the stratosphere, crucial in producing the 20dw0. The meteor radar wind spectra suggested that the excited 20dw0 possibly engages in non-linear interactions with SW2, further generating secondary waves in the MLT. Therefore, this study presents the observational evidence of a two-step non-linear interaction associated with zonally symmetric planetary waves during major SSWs.