bluuebunny/crossref_metadata_2025 huggingface dataset:
The interannual and decadal sea level variabilities over the Indo-Pacific Oceans in the Reanalysis and CMIP6 Historical Simulations and Projections
Authors: Maya Ponni , Álvarez Antolínez José Antonio , Js Deepa , Gnanaseelan Chellappan
Published: March 2024

In climatological research, understanding past and accurately simulating future sea level variability is paramount due to the considerable risk that sea level changes pose to low-lying regions, coupled with their significant influence on the occurrence and severity of extreme meteorological events  . This research insights are vital in evaluating the potential impact on renewable energy sources, particularly offshore wind, wave, and tidal energy, where changes in sea level can significantly alter the efficiency and viability of these energy converters. This study comprehensively analyses sea level variability on interannual and decadal scales in the Indo-Pacific region, integrating data from the Ocean Reanalysis System 5 (ORAS5), CMIP6 historical simulations spanning from 1850-2014, and future projections under the CMIP6 future intermediate emission scenario (rcp245/ssp245) for the period 2015 to 2100. Our investigation spans key areas such as the Northwest Central Pacific Ocean (NWCPO), the Eastern Equatorial Pacific Ocean (EEPO), and the Thermocline Ridge of the Indian Ocean (TRIO), among others.We report findings on interannual and decadal Sea Level Anomaly (SLA) variability, especially highlighting the TRIO region and various Pacific Ocean zones such as the SWPO, NWCPO, EEPO, and NWNPO. Our study identifies a substantial increase in interannual variability in the NWNPO. We also observe consistent sea-level variability patterns across these regions, extending into future projections under moderate emission scenarios.We find that the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole, and the Pacific Decadal Oscillation are key drivers of these variabilities. Our study reveals a strong connection between sea levels in the Equatorial Pacific and the Niño 3.4 index, suggesting its potential as a sea level-based indicator for El Niño and La Niña events.Our research highlights the critical role of atmospheric forcing in driving sea level variability. We link high sea-level variability regions to significant wind stress curl anomalies, with distinct differences between hemispheres. We explore the mechanics of equatorial variability, emphasizing the role of equatorial Kelvin waves and local and remote Rossby waves in different oceanic regions.Our study concludes that most CMIP6 models, despite large model uncertainty, predict an increase in sea level variability for the upcoming century, particularly in the Pacific Ocean, emphasizing the need for heightened attention to this dynamic region in the context of global climate change .
Impact of sediment transport on newly constructed embankments and flooding in the Nakkhu River, Kathmandu, Nepal
Authors: Thapa Saraswati , Sinclair Hugh D. , Creed Maggie J. , Mudd Simon M. , Attal Mikael , Borthwick Alistair G. L. , Ghimire Bhola N.
Published: March 2024

In Nepal, urbanization has significantly accelerated since 2017 due to the conversion of numerous rural administrative units into urban ones by the government. This trend is particularly pronounced in the Kathmandu Valley where development is taking place on a large scale, including the building of four smart satellite cities, an outer ring road and river corridor roads flanked by green belts. The result is increased urban sprawl, river channelization, and floodplain encroachment, accompanied by sand and gravel mining activities. Many embankments have been constructed for flood protection along the rivers in the Kathmandu valley, including the Nakkhu River. However, the increasing number of settlements in low-lying floodplain areas and associated infrastructure damage caused by overtopping, breaching, or seepage of embankments, raise questions about the long-term sustainability of embankments as a solution to prevent future floods.Using numerical simulations in a coupled hydrodynamic and landscape evolution model, CAESAR-Lisflood, we investigate how such embankments affect sediment transport, channel geometry, conveyance capacity, and flood inundation along the Nakkhu River. Each simulation is based on a high-resolution digital elevation model (2 m pixels, acquired in 2019-2020). Input sediment grain sizes are derived from field measurements, and we drive the model for different flood scenarios using maximum daily discharge data provided from the Department of Hydrology and Meteorology, Nepal.The results suggest that changes in channel geometry caused by sedimentation increase flood risk downstream, particularly where embankments have been built to replicate sinuous channel courses. Inundation area is significantly higher in a scenario that includes sediment transport compared to a flood event modelled without sediment. It is recommended that sediment transport analysis be undertaken in the routine design of embankments and planned developments for river floodplains to minimize flood risk. Our study indicates that the construction of embankments alone may not provide sustainable long-term protection against future floods in rivers carrying high sediment loads.Keywords: River embankment; Sediment transport; River morphology; Flood modelling; Nepal
Subaqueous bedform morphology and migration in a mountainous macrotidal estuary
Authors: Liu Ruiqing , Cheng Heqin , Teng Lizhi , Ren Zhongda , Chen Jinfeng , Yang Qian , Fan Heshan
Published: March 2024

Abstract: The subaqueous bedforms in mountainous macrotidal estuaries, distinguished by their large tidal range and strong tidal and river flow dynamics, exhibit complex interactions among hydrodynamics, sediment transport, and bedform morphology, setting them apart from river and marine bedforms. However, there is currently a lack of research on the development characteristics and mechanisms of bedforms in such estuaries. To address this gap, field observations were conducted in the Minjiang Estuary of the East China Sea in December 2021 and August 2023, utilizing multibeam echosounders, shallow seismic profilers, and Acoustic Doppler Current Profilers (ADCP). Field measurements, including bedform morphology, surface sediment grain size, and hydrodynamics, were collected during both flood and ebb seasons. The study aims to explore the development characteristics and evolutionary patterns of bedforms in mountainous macrotidal estuaries, using the Minjiang Estuary as a representative case. The results indicate that the surface sediments in the subaqueous delta plain to the delta front channel of the Minjiang Estuary are predominantly composed of gravelly sand, with a median grain size ranging from 12.77 to 724.51 µm. Large compound bedforms are prevalent, with wavelengths ranging from 7.23 to 233 m and heights from 0.1 to 11.42 m. Bedform size is positively correlated with sediment grain size in the respective regions, and bedform morphology is related to sediment composition and water depth. Bedforms in different regions of the Minjiang Estuary exhibit varying degrees of symmetry, with asymmetry being more common, occasionally interspersed with cosinusoidal bedforms exhibiting better symmetry, which correlates with the strength of regional tidal dynamics. This study is of significant importance for understanding and simulating estuarine hydrodynamics and sediment transport.Keywords: Mountainous Macrotidal Estuary, Minjiang Estuary, Bedform Morphology, Subaqueous Bedforms, Tidal Currents
What impacts the soil moisture dynamics in the near-natural beech forest?
Authors: Azekenova Alina , Feger Karl-Heinz , Julich Stefan
Published: March 2024

Soil moisture in forested regions displays considerable spatial and temporal variability within the soil-plant interaction. The high frequency of drying and wetting cycles exacerbates the uncertainty in this already complex relationship. Recent studies in forest hydrology have frequently postulated that soil physical properties and precipitation partitioning induce soil water content (SWC) variability. However, in-situ evidence for this linkage is scarce. To support the notion of SWC patterns corresponding to these two elements, a transect-based method was utilised. It clarifies the variation in soil moisture on a small scale and facilitates the identification of specific patterns with the distance from the tree stem. An intensive monitoring of SWC (52 profiles) and precipitation, including throughfall and stemflow, has been carried out in the near-natural beech forest in north-eastern Germany since 2022. It covers three study sites that are stocked over a terminal moraine and are classified as wet, intermediate and dry on the basis of the soil moisture gradient. The result stipulates increase of the SWC away from the stem during drying cycles at the dry study site. However, this appears to be the reverse for the wet site. During the wetting phase, soil moisture at intermediate and dry sites exhibited homogeneous variation, although the wet site experienced an increase in soil moisture by stem distance. Therefore, uncovering the distance from stem, root density distribution and canopy structure as possible controlling factors.  It is concluded, that within soil-plant interaction both soil physics and precipitation define the patterns of soil moisture variation during wetting cycles. Conversely, soil retention characteristics mainly anticipate water fluxes in the soil during drying periods.
EISCAT_3D – Volumetric Phased-Array Incoherent Scatter Radar in the European Arctic
Authors: Ulich Thomas , Häggström Ingemar , Steuwer Axel , Tjulin Anders , Enell Carl-Fredrik , Mihalikova Maria ,   EISCAT Staff
Published: March 2024

The EISCAT Scientific Association is currently building the most advanced 3-dimensional imaging radar for atmospheric, ionospheric and near-Earth space investigations. The fully steerable, tri-static, phased-array incoherent scatter radar is located in Skibotn (inland from Tromsø, Norway), Karesuvanto (Finland, north of Kiruna), and Kaiseniemi (Sweden, west of Kiruna). The transmit-receive array at Skibotn consists of about 10,000 aerials and ten 91-aerial outrigger receivers in the immediate vicinity. The receive-only arrays of Kaiseniemi and Karesuvanto consist of about 5,000 aerials each. Construction of the facility began after the project kick-off in September 2017. During 2024, EISCAT_3D will gradually begin operations, starting with a seven-element test system and expanding from that. EISCAT_3D will replace the EISCAT mainland radars, i.e. the mono-static, 930-MHz UHF radar at Tromsø and the tri-static, 224-MHz radar at Tromsø with additional receivers at Sodankylä (Finland) and Kiruna (Sweden). The EISCAT Svalbard Radar (ESR) and the Ionospheric Heating facility at Tromsø will not be affected by EISCAT_3D becoming operational. Here we give an status update of the new facility. EISCAT_3D is a European Strategy Forum for Research Infrastructures (ESFRI) Landmark in the Environment domain.
High and dry: model development to improve simulations of large-scale hydrological droughts in the Alps  
Authors: Janzing Joren , Wanders Niko , Brunner Manuela
Published: March 2024

Hydrological droughts are often not limited to a single river basin but affect several basins simultaneously. The co-occurrence of droughts in different basins is influenced by meteorological processes, catchment characteristics and surface processes such as soil moisture and snow cover, the latter of which is particularly important in mountain regions.Large-scale hydrological models are a useful tool to study the drivers of large-scale droughts and to understand their evolution in a changing climate. In recent years, these models have moved towards increasingly high spatial resolutions, making them more applicable in regions with complex heterogenous mountain topography. However, large-scale hydrological models often have simplified representations of snow and glacier processes.Here, we set up the PCR-GLOBWB 2.0 global hydrological model, which represents snow cover by using a temperature index model with a constant degree-day factor and which has no explicit representation of glaciers, at a resolution of 30 arcseconds (approximately 1 km) over the Alps. We adapted the model to make it more suitable for mountain regions. Specifically, we (1)  improved the snow module and compare different implementations of temperature-index models and (2) implemented a new dynamic glacier module. In the new model set-up, we calibrated snow water equivalent and glacier elevation changes against observations and reanalysis products and evaluated the model over the Alps, with specific emphasis on the representation of spatial patterns in hydrological extremes. With this new set-up, we are able to tackle model issues related to excess snow accumulation and improve discharge simulations, particularly in glacierized catchments. We apply this new model set-up to the larger Alpine region to study the drivers of large-scale hydrological droughts.
Development of Polar Lows in Future Climate Scenarios over the Barents Sea
Authors: Lin Ting , Rutgersson Anna , Wu Lichuan
Published: March 2024

Polar lows (PLs) are intense mesoscale cyclones that form over polar oceans during colder months. Characterized by high wind speeds and heavy precipitation, they profoundly impact coastal communities, shipping, and offshore activities. Amid the substantial environmental changes in polar regions due to global warming, PLs are expected to undergo noteworthy transformations. In this study, we investigate the response of PL development in the Barents Sea to climate warming based on two representative PLs. Sensitivity experiments were conducted including the PLs in the present climate and the PLs in a pseudo-global warming scenario projected by the late 21st century for SSP 2-4.5 and SSP 3-7.0 scenarios from CMIP6. In both warming climate scenarios, there is an anticipated decrease in PL intensity, in terms of the maximum surface wind speed and minimum sea level pressure. Despite the foreseen increase in latent heat release in the future climate, contributing to the enhancement of PL intensity, other primary factors such as decreased baroclinic instability, heightened atmospheric static stability, and reduced overall surface heat fluxes play pivotal roles in the overall decrease in PL intensity in the Barents Sea under warming conditions. The augmentation of surface latent heat flux, however, results in increased precipitation associated with PLs by enhancing the latent heat release. Furthermore, the regional steering flow shifts in the warming climate can influence the trajectory of PLs during their development.
Quantifying health-related climate metrics of extreme temperature disasters: An international analysis over five decades
Authors: Lindersson Sara , Messori Gabriele
Published: March 2024

Understanding the relationship between extreme temperature events and health outcomes necessitates integration of hazard and impact data. International databases of societal impacts from disasters serve as an important data source for empirical cross-country analyses. Yet, detailed and precise estimations of the hazard magnitude of these impact records are often lacking. Physical metrics play a pivotal role in, for instance, statistical analyses and exposure assessments.In bridging this gap, our work leverages recent advancements in geocoding of disaster records alongside high-resolution meteorological datasets to construct an inventory of a diverse range of health-related climate metrics. Our global analysis spans over 200 records of extreme temperature disasters from the past fifty years. By doing so, we unveil insights into the properties of these disastrous heat- and cold-waves. We furthermore explore differences across space, time, metrics, and data sources. This work highlights the potential of utilizing this integrated approach to extract meaningful information from historical disaster records in global databases, aiding climate resilience and public health strategies.
The sea ice component of MUSE, the unstructured-mesh global ocean model of CMCC
Authors: Cocetta Francesco , Zampieri Lorenzo , Iovino Doroteaciro
Published: March 2024

The rapidly evolving sea ice cover requires novel modeling approaches and mathematical techniques to accurately simulate the sea ice dynamics, thermodynamics, and its interactions with the atmosphere and ocean at varying spatiotemporal resolutions. In this context, the CMCC is developing the Multiscale Unstructured model for Simulating the Earth’s water environment (MUSE), a novel global ocean-sea ice model on unstructured meshes.MUSE employs a finite-element numerical discretization on unstructured meshes, aiming at offering flexibility in simulating the global ocean for various applications, ranging from physical process understanding to operational sea ice predictions. The ongoing implementation of the sea ice component utilizes the traditional continuous sea ice formulation and the 2+1 split assumption, meaning that the sea ice dynamics and advection are solved for horizontal motions while the thermodynamics and radiative processes are parameterized at the subgrid scale.   MUSE employs a modified elastic-viscous-plastic (mEVP) solver for the sea ice dynamics and a Flux Corrected Transport (FCT) advection scheme, alongside the state-of-the-art column physics package "Icepack" maintained by the CICE consortium.Here, we describe the global implementation of the sea ice component in MUSE and its coupling with the ocean. We present the resulting representation of vertical thermodynamic processes and horizontal dynamics of sea ice.
Baroclinic stability at low latitudes: Explaining subtropical jet variability in observations
Authors: Lachmy Orli , Peles Oren
Published: March 2024

The subtropical jet is characterized by a strong vertical shear and is usually located far equatorward of the maximum surface westerlies. In some cases, strong westerlies develop below the subtropical jet, indicating that momentum flux convergence by baroclinic eddies contributes to the jet driving. In this work we examine this variability of the subtropical jet in light of baroclinic instability theory. According to linear baroclinic instability theory, the vertical scale of eddy fluxes decreases toward the equator, making the eddies effectively stable at low latitudes. This stabilizing effect enables the subtropical jet to be maintained by angular momentum advection from the tropics, without the development of baroclinic eddies and surface westerlies below the jet. The dimensionless Charney number is used as an indication for the degree of baroclinic stability at low latitudes. This number incorporates the stabilizing effect at low latitudes, in contrast with the commonly used measure for baroclinicity – the Eady growth rate. It is found that the Charney number performs better than the Eady growth rate in estimating the lowest latitude of baroclinic growth and explaining subtropical jet variability. 
Temperature “Memory” and Natural Rock Fracture at Earth’s Surface
Authors: Eppes Martha-Cary , David Christian , Heap Mike , Baud Patrick , Bonami Thomas , Dahlquist Maxwell , Keanini Russell , Lacroix Cyril , Rasmussen Monica , Rinehart Alex , El Alaoui Youness , Windenberger Adrien
Published: March 2024

Rock physics theory and experimental data suggest that fracture growth in rock proceeds not only as a function of synchronous stress and environmental conditions but also as a function of past fracture growth in response to those conditions. ‘Stress memory’ or ‘fatigue-limit’ fracture mechanics phenomena such as the Kaiser effect epitomize this idea. Many questions exist, however, as to if and how these phenomena impact the growth of fractures under natural environmental conditions. For example, to what extent does the orientation of past experienced stresses manifest in a rock’s response to stresses of the same magnitude?Here we test for a memory of intergranular thermal stresses in two natural granite boulders of the same lithology for which we have 1 and 3 years of known temperature history, respectively. We hypothesize that cores extracted from the exterior portions of the boulders – that have necessarily experienced more and larger temperature fluctuations – will have more ‘memory’ of peak temperatures than those cores extracted from the boulder centers. In turn, we hypothesize that outer cores will crack less in response to temperature cycling than inner cores. For the first boulder, we measured P-wave velocities and connected porosities before and after 4 different oven heat treatments – heating up to 40, 45, 50 and 65 °C at a rate of at 20 °C/hr and cooling at an ambient rate over several cycles each. For two transects of cores extracted from the natural upward facing surface down, and the natural west-facing surface inward, we found that porosities increased after each subsequent heat treatment, but by larger amounts with distance away from the outer rock surface, as hypothesized. P-wave velocities, however, both increased and decreased with different heating cycles and positions. Therefore, for the second boulder, we extracted a top-down transect of 5 cores and, using a special-made rig, found that the samples exhibit significant P-wave velocity directional anisotropy. We subjected these cores to the same heat treatments as those of the first boulder, but this time orienting the samples identically in the oven with respect to their original positions in the boulder. Preliminary data show similar results as the first boulder, with the outermost core cracking the least (as interpreted from porosity changes) relative to the inner cores. Ongoing work will examine changes in P-wave velocity in different directions relative to measured anisotropy as a function of heat treatment cycles. This work has important implications for understanding if and how, with ongoing global warming, Earth’s rocks will respond to ‘new’ temperatures. 
Electrooxidation for the removal of Sulfamethoxazole using graphite electrodes
Authors: Joshy Anju , Goel Sudha
Published: March 2024

Sulfamethoxazole is a sulfonamide class antibiotic commonly used to cure infections caused by bacteria in humans and animals. Sulfamethoxazole is considered a contaminant of emerging concern and is one of the most frequently found antibiotics in the environment. It has proven to be highly stable and persistent in the environmental matrices, with a half-life of more than 100 days in an aqueous environment under specific environmental conditions. This causes a severe threat to human and environmental health. The presence of residue of sulfamethoxazole in water matrices shows hazardous effects on aquatic life, affecting the physiological behaviour and reproductive capacity of aquatic organisms. Sulfamethoxazole also showed potential negative impacts on the microbial communities. The persistence of these compounds for an extended period in the environment leads to the formation of antibiotic-resistant genes in bacteria, which can affect the proper functioning of the ecosystem. In this current study, the effectiveness of the electrooxidation process on the removal of sulfamethoxazole using graphite electrodes was investigated. The effect of different parameters like the electrolysis time, current density, initial concentration of sulfamethoxazole, electrolyte concentration (NaCl or Na2SO4), and initial pH of the sample solution were evaluated. Out of the various parameters, it was found that current density (1-10 mA/cm2), electrolyte concentration (100- 500 mg/ L), and the electrolysis time (0-1h) are the key parameters that determine the efficiency of the electrooxidation treatment process. It was found that for the current density value of 10 mA/ cm2, within 45 min of electrolysis time, nearly 99% of the sulfamethoxazole degradation occurred. The possible sulfamethoxazole degradation mechanisms and resulting by-products were analyzed using the Liquid chromatography-mass spectroscopy (LC-MS). Degradation kinetics were also evaluated for the electrooxidation treatment process. The results from the current study showed that electrooxidation could be a favourable treatment technique for the removal of sulfamethoxazole from water matrices.
Crop modelling with AquaCrop during climate change in the Ancash region of the Peruvian Andes
Authors: McGuire Patrick C. , Singarayer Joy S. , Wade Andrew J. , Rodda Harvey J.E. , Branch Nicholas P. , Joseph Mattam Dionisa , Araujo-Ferreira Francisco , Capoen Eric , Everhart Alden A. , Florencio Christian , Gonzalez Fernando , Herrera Alexander , Lane Kevin , Meddens Frank M. , Santos Shupingahua Diana , Timaná Martín E. , Walsh Douglas
Published: March 2024

Peruvian Andean rural farmers often have precarious livelihoods and already experience less predictable weather conditions than in recent decades. With the goal of investigating hydrological and agricultural resilience in a region with an uncertain climate future (with regard to both temperature and precipitation), we present here the results obtained from using the AquaCrop software to model both crop growth and the consequent harvest yields in the valleys of the Peruvian Andes, including the Rio Santa Valley in the Ancash region. The crop models are presented for 1970-2099 (the historical and the future during climate change), using RCP2.6 & RCP8.5 Regional Climate Models (RCMs) from CORDEX at a spatial resolution of 0.22 degrees. We chose the CORDEX RCM data that was dynamically downscaled from the CMIP5 GCMs instead of the CHELSA statistically-downscaled data, since the downscaling of the CORDEX RCM data produces more locally-heterogeneous climate averages, which are more consistent with the variable topography. The CORDEX RCM model data has subsequently been bias-corrected to monthly CHIRPS precipitation and monthly ECMWF ERA-Interim temperature extremes from 1981-2005 for locations in the Ancash region, including Yungay and Aija. For the various crops that we modelled (maize/corn, potatoes, dry beans, quinoa, wheat), we find significant interannual variability of the dry yields from crop harvest (without irrigation or fertilizers), particularly when the climate is transitioning to a warmer one for those crops that prefer warmer climates. Without the consideration of irrigation or fertilizers, the possibility of high yield interannual variability could make it difficult for the Peruvian Andean farmers to plan ahead, and maintaining a diversity of crops within the Rio Santa Valley and the wider Ancash region could be advantageous for these farmers.
Misconceptions of the marine biological carbon pump in a changing climate: Thinking outside the “export” box
Authors: Landolfi Angela , Frenger Ivy , Kvale Karin , Somes Christopher J. , Oschlies Andreas , Yao Wanxuan , Koeve Wolfgang
Published: March 2024

The marine biological carbon pump (BCP) stores carbon in the ocean interior, isolating it from exchange with the atmosphere and thereby coregulating atmospheric carbon dioxide (CO2). As the BCP commonly is equated with the flux of organic material to the ocean interior, termed “export flux,” a change in export flux is perceived to directly impact atmospheric CO2, and thus climate. Here, we recap how this perception contrasts with current understanding of the BCP, emphasizing the lack of a direct relationship between global export flux and atmospheric CO2. We argue for the use of the storage of carbon of biological origin in the ocean interior as a diagnostic that directly relates to atmospheric CO2, as a way forward to quantify the changes in the BCP in a changing climate. The diagnostic is conveniently applicable to both climate model data and increasingly available observational data. It can explain a seemingly paradoxical response under anthropogenic climate change: Despite a decrease in export flux, the BCP intensifies due to a longer reemergence time of biogenically stored carbon back to the ocean surface and thereby provides a negative feedback to increasing atmospheric CO2. This feedback is notably small compared with anthropogenic CO2 emissions and other carbon-climate feedbacks. A comprehensive view of the BCP's impact on atmospheric CO2, is a prerequisite for assessing the effectiveness of marine CO2 removal approaches mediated by biology.
Advances in the numerical modeling strategy (concept) of a generic nuclear waste repository in crystalline rock
Authors: Guevara Morel Carlos , Thiedau Jan , Maßmann Jobst
Published: March 2024

Safe deep geological disposal of heat-generating nuclear waste requires an accurate assessment of barrier integrity. Therefore, the evaluation of the coupled mechanical, hydraulic, thermal and chemical processes, occurring in the host rock due to the nuclear waste storage, excavation among others is needed. For this purpose, numerical modeling is an essential and powerful tool. This contribution focuses on a generic repository system that relies on a Containment Providing Rock Zone (CRZ) in a crystalline rock, which acts as the principal containment barrier according to German law. Using the open-source finite element code OpenGeoSys version 6, a closer look at the CRZ regarding the influence of fractures on the local hydraulics and potentially available rock zone volume for repository emplacement is shown.Since fractures and other type of discontinuities usually characterize crystalline rock, they are expected to influence the hydraulic behavior of the system. Hence, their representation in numerical models becomes non-trivial. Here a comparison between different numerical fracture representations and their impact on the hydraulic regime surrounding the CRZ, is presented.Due to the presence of fractures, it cannot be assumed that a sufficiently large area in which to emplace the waste will be found. As a consequence, multiple smaller CRZs [1], each providing undisturbed rock, have to be defined. Typically, it is only possible to characterize fracture networks statistically, which leads to the use of stochastically generated discrete fracture networks. Using a geometrical characterization of the potentially undisturbed CRZs based on a stochastically generated discrete fracture network, a methodology is proposed to evaluate the feasibility of the multiple CRZs concept.References[1] Thiedau, J., et al.: CHRISTA-II - Analysen zur Integrität von geologischen Barrieren von Endlagersystemen im Kristallin. Ergebnisbericht, Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover, 202
A two-stage river capture event in Corsica and its impact on erosion rates and offshore sedimentation
Authors: Malusa' Marco Giovanni , Resentini Alberto , Wittmann Hella
Published: March 2024

The source-to-sink system of the Golo River, the largest catchment of Corsica (Western Mediterranean) is a well-established test case for inferring erosion rate variations from the sedimentary record in a quiescent tectonic setting. Previous studies have analyzed the onshore part of the source-to-sink system during late Quaternary climatic and sea level variations, and the offshore sink to highlight the main variations in sediment yield during the late Pleistocene and the last glacial cycle. Here we expand the analysis of the river network of Corsica and of the offshore sink back to the Miocene, when the region was still tectonically active. Based on a unique set of geological and in situ 10Be cosmogenic data, we show how the landscape have responded and is still responding to the disequilibrium caused by the late Miocene uplift of Alpine Corsica, and we provide evidence of a two-stage river capture event affecting the river network during the Pliocene. Our data reveal that ~1280 km2 of basin area originally draining towards the Ligurian Sea was abruptly connected in the Pliocene to the Tyrrhenian Sea through headward erosion. River capture led to the formation of a large Pliocene-Quaternary submarine fan offshore the Tyrrhenian coast, associated to an increased sediment yield that was three times greater than the average sediment yield in the same source-to-sink system during the Holocene. Such a major change in sediment flux towards the Tyrrhenian margin was greater magnitude than any subsequent peaks in sediment yield documented during Pleistocene glaciations. In situ 10Be cosmogenic data demonstrate that erosion is focused on previous capture sites even today, which indicates persistence of disequilibrium after millions of years. Our findings suggest that using the sedimentary archive to infer tectonic growth of topography or climate changes is not straightforward and may lead to incorrect interpretation unless river piracy can be safely excluded.
Close-range thermal remote sensing over a cryospheric landform in complex topography – challenges and lessons learnt
Authors: Naegeli Kathrin , Adams Jennifer Susan , Bramati Gabriele , Gärtner-Roer Isabelle , Rietze Nils
Published: March 2024

Close-range remote sensing often fills the gap between in situ measurements and space-based observations. While most platforms are equipped with RGB cameras, there is a growing availability of thermal infrared (TIR) cameras. Both Uncrewed Aerial Vehicles (UAV) surveys in general and TIR remote sensing pose their individual challenges, especially in complex topography. In particular, TIR datasets are far from being ready-to-use upon acquisition, and thorough post-processing is required. However, they offer a great potential to monitor cryospheric landforms and assess their surface energy budget and related dynamics.In this contribution, we present two years of TIR and RGB UAV data in combination with multiple in situ measurements, both for calibration and validation, obtained for a creeping permafrost landform, rock glacier Murtèl in the Engadine, Switzerland. We highlight the challenges evoked by the complex topography in the alpine environment (e.g. irradiance distribution, wind) and shed light on varying correction possibilities (e.g. laboratory-, field-, camera-based) that allow for a more accurate retrieval of land surface temperature over middle-sized landforms, such as a rock glacier.In light of future thermal infrared satellite missions, an appropriate use of close-range remote sensing techniques, including survey protocols for calibration and validation, is urgently needed. This application study contributes to a better across-scale methodological understanding of sensors and methods, as well as the role of close-range remote sensing in complementing in situ and space-based observations, but also illustrates the potential of TIR datasets for cryospheric process understanding and long-term monitoring.
A cloud product for Sentinel-4 to support the Geo-Ring for Air Quality
Authors: Lutz Ronny , Molina Garcia Victor , Argyrouli Athina , Romahn Fabian , Loyola Diego
Published: March 2024

The Geo-Ring for Air Quality consists of three geostationary instruments to monitor the air quality and atmospheric composition over large parts of the northern hemisphere with a high temporal cadence. These are the Korean Geostationary Environmental Monitoring Spectrometer (GEMS, launched 2020), the US-American Tropospheric Emissions: Monitoring of Pollution (TEMPO, launched 2023) and the European UVN spectrometer on Sentinel-4 (S4, to be launched 2025). These geostationary instruments can benefit substantially from the knowledge gained by heritage LEO missions like OMI/Aura, GOME-2/MetOP-ABC and TROPOMI/Sentinel-5P and provide a great synergistic potential to combine the global spatial coverage of the LEO missions with the regional high temporal coverage of the GEO missions.Although trace gases and greenhouse gases are the main focus of the Geo-Ring for Air Quality, knowledge about the presence and characteristics of clouds is a pre-requisite for an accurate retrieval of the aforementioned species for air quality. On top of that, clouds by themselves are an important parameter for climatological studies and applications via their importance and impact on the Earth’s radiation budget.In this contribution, we present the operational cloud product developed for Sentinel-4. It is based on the algorithms called OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks), which are already being in operational use for several heritage missions like GOME-2 and TROPOMI. The main retrieval parameters are cloud fraction, cloud mean height, cloud top height, cloud optical thickness and cloud albedo, achieved via two different cloud models: a simplified Lambertian reflector approach (CRB, clouds as reflecting boundaries) and a physically more realistic scattering layer approach (CAL, clouds as layers). As a testing scenario for the Seninel-4 development, the OCRA algorithm has been adapted to the GEMS instrument. We will show application results and also further comparisons of the S5P OCRA/ROCINN cloud product with the GEMS cloud product.
Vertical distribution of organic tracer compounds in atmospheric aerosols: analysis of low-volume samples from meteorological balloon flights
Authors: Jaén Flo Clara , Díez Palet Isabel , Marco Asensio Esther , Grimalt Obrador Joan , Fernández Ramón Pilar , van Drooge Barend
Published: March 2024

The evolution and intensity of air pollution episodes are significantly influenced by atmospheric conditions. In particular, stagnant conditions and thermal inversions often involve precautionary health warnings in populated areas. These conditions restrict the dispersion of pollutants leading to exacerbated air quality in the lower layer of the troposphere. Additionally, photochemical reactions contribute to qualitative and quantitative changes in aerosols, with secondary organic aerosols (SOA) formation processes that are not fully understood. This study aims to investigate the vertical distribution of particle-bound organic compounds and Black Carbon (BC) under both temperature inversions and standard ambient lapse rates.Total suspended particles were simultaneously collected on filters at two different heights (1 m and 400 m) with tethered balloons equipped with low-volume air pumps and BC monitors for periods of 3-hours. Sampling campaigns were performed in industrial, sub-urban and rural background sites in different seasons during 2021 and 2022. Furthermore, sampling was conducted at two different elevations within the city of Barcelona.Particle-bound organic molecular compounds were analyzed in the low-volume samples (
Exploring the Impacts of Antibiotics in Manure on Soil Nitrogen Dynamics and Plant Growth in Grasslands
Authors: Yang Zhongchen , van Groenigen Jan Willem , Berendsen Bjorn J.A. , van de Schans Milou G.M. , De Deyn Gerlinde B.
Published: March 2024

Animal manure often contains antibiotic residues due to the prevalent use of these compounds in animal husbandry. After manure application, these residues could potentially affect soil microorganisms and plant growth, yet their impacts on soil nitrogen (N) dynamics in grasslands remain largely unexplored. We hypothesized that applying manure containing antibiotics would shift soil N dynamics by affecting plant morphology and certain N-cycling microbial guilds such as symbiotic N-fixing bacteria. To test this, we conducted a 64-day greenhouse experiment using field soil and including four plant treatments (no plants, ryegrass monoculture, clover monoculture, and a ryegrass-clover mixture) and three fertilizer treatments (antibiotic-free manure, manure containing oxytetracycline, and manure containing sulfadiazine). We measured nitrous oxide (N2O) emissions, N content in the shoot and root biomass, and antibiotic uptake in plant shoots, and used the δ15N technique to estimate symbiotic N fixation of clover. We also sampled soils at the end of the experiment to measure plant-available N pools (ammonia and nitrate) and the abundance of symbiotic N-fixing bacteria (by nifH gene). Our results showed that antibiotics in manure did not significantly alter soil N2O emissions, soil N pools, or plant aboveground N in any plant community. Both compounds were barely been taken up in plant shoots. However, both antibiotics significantly reduced root biomass in clover monocultures. Despite this root growth inhibition, N fixation (both aboveground and belowground) in clover monoculture was unaffected by both antibiotics. Interestingly, analysis of variance suggested that antibiotics in manure could lead to a higher abundance of nifH gene in soil than that of antibiotic-free manure in clover monoculture. In summary, although overall soil N dynamics were not impacted by antibiotics in manure, root growth inhibition in clover monoculture suggests varying grassland species susceptibilities to antibiotic stress. Our results also suggest that clover may adapt to antibiotic stress by modifying plant-microbe interactions. This study calls for further research on long-term environmental impacts of antibiotic residues in grasslands.
Sea surface temperatures across the low-latitude Indo-Pacific Ocean during the Holocene, Last Interglacial and Marine Isotope Stage
Authors: Hollstein Martina , Prange Matthias , Jonkers Lukas , Mohtadi Mahyar
Published: March 2024

The Indo-Pacific Warm Pool (IPWP) holds the largest warm water body on Earth. With sea surface temperatures (SST) above 28°C, it promotes deep atmospheric convection in the rising limb of the Hadley and Walker circulation cells, and is a major source of heat and moisture to the global atmosphere with far-reaching climate impacts. Spatiotemporal changes in SST influence the location and strength of atmospheric convection and thus the atmospheric circulation. Despite its importance for the global climate, long-term SST variability across the IPWP is not well understood yet. Compilations of proxy-based reconstructions of SST during previous interglacials combined with climate models provide ideal means to study the SST variability in response to varying astronomical forcing. Hitherto, global compilations of interglacial SST anomalies and data-model comparisons have mostly focused on the Holocene and the Last Interglacial (LIG) period. The available studies reveal a striking mismatch between proxy-derived and modelled SST anomalies across low latitudes. However, the data coverage across the low-latitude Indo-Pacific is poor with little to no data from the IPWP. Here, we compare a proxy network of SST anomalies from the low-latitude Indo-Pacific during Holocene, LIG and MIS 11 time slices to the output of CESM 1.2 climate model simulations. We find large discrepancies between the proxy network and CESM output, concerning the magnitude and pattern of SST change including zonal gradients across the tropical Pacific. For instance, proxy data indicate highest SSTs during the LIG, with a slight warming as compared to the preindustrial reference period, while CESM indicates lowest SSTs during the LIG. By performing individual forcing experiments with CESM, we disentangle the roles of astronomical forcing, greenhouse gas concentration and vegetation cover in shaping interglacial tropical SST patterns. In particular, we find that an expanded Northern Hemisphere vegetation cover during interglacials mitigates model-data discrepancies in IPWP temperatures. 
Regional hotspots of Hengduan plant endemism inferring local speciation in response to connectivity
Authors: Yuan Zili
Published: March 2024

The Hengduan Mountains (HDM) is one of the most biologically diverse mountain ranges on the planet, with exceptionally high levels of endemism. We expect that the geological and climate changes of the regions shaped endemism though dispersal and speciation processes by modulating landscape connectivity. Here, we characterise the plant endemism in the HDM, by mapping the distribution of 3,165 endemic species, representing approximately 25% of the total plant species richness. We show that endemic richness is highest along the southern front of the HDM, and especially concentrated along the Shangri-la Plateau and the three-river parallel region at elevations between 2,700 and 4,200 meters a.s.l. We demonstrate a geographically differentiated effect of connectivity on endemic richness and composition. In the endemic hotspot, we find a negative connectivity-diversity relationship, while we find a positive connectivity diversity relationship in the northern and southern HDM. Our result suggests a dominant role of isolation-induced allopatric speciation. Low connectivity may facilitate allopatric speciation in shaping distinct lineage in central HDM; while in the north of HDM, similar cold habitats in high elevation where habitats are more connected than the southern part, have likely facilitated species migration during the Quaternary glaciation. Thus, the degree of connectivity varied within HDM depending on their topographical configuration. Geographic contrasts in diversity further match endemic composition, which suggest the effect of geological history in shaping the diversity and composition of this exceptional flora. Overall, we conclude that landscape connectivity is a key driver of endemic plant speciation in HDM, explaining richness patterns that cannot be explained by temperature and other classic predictors.
­Drivers of Indo-Pacific upper ocean heat and freshwater variability using a synthesis of coral proxies and ocean models 
Authors: Murty Sujata , Ummenhofer Caroline , Wang Shouyi , Gruenburg Laura , Biastoch Arne , Böning Claus
Published: March 2024

The Maritime Continent provides pathways for heat and freshwater transport from the Pacific to the Indian Ocean, serving as an important oceanic teleconnection for Indo-Pacific climate. Yet, the short length of robust observational datasets limits examination of past Maritime Continent and Indo-Pacific Warm Pool variability and the resulting implications for Indo-Pacific climate. Coral proxy records allow insights into variability on seasonal to multi-decadal timescales prior to the period of satellite and in situ observations. Here, we synthesize published coral δ18O records, in situ observations, and simulated ocean variability (salinity, temperature, thermocline depth, heat content) from the Nucleus for European Modeling of the Oceans (NEMO) ocean model simulations to explore drivers of seasonal to multi-decadal variability across the Indo-Pacific Warm Pool (western Pacific, Maritime Continent and central Indian Ocean). This proxy-model synthesis allows for examination of thermohaline vertical variability along key oceanic pathways. We identify the role of key climate modes, including the Interdecadal Pacific Oscillation, in driving upper ocean Indo-Pacific variability. The proof-of-concept provided by these results suggest that the paleoproxy records capture important features of regional hydrography and the associated variability in upper ocean heat and freshwater budgets. Such proxy-model comparison at a broader spatial scale is critical for understanding the drivers of variability related to changes in Indo-Pacific oceanic teleconnections over recent centuries and provides important context for projecting future changes in the region.