bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth and Lateral Propagation of Fault-related folds in the Shiwalik of Kumaon Himalaya: Mechanism and Geomorphic signatures
Authors: Ansari Mohd Azhar , N. Malik Javed , Dhali Mitthu
Published: March 2024

The Kumaon Himalaya is one of the most seismically dynamic regions of the Central Seismic Gap (CSG), falling into Seismic Zone V along the Himalayan arc. The 21 km long NW-SE trending Kaladungi Anticline in Kumaon Himalaya is the topographic manifestation of an actively growing fault-bend fold formed in the hanging wall of the kaladungi fault (KF). It, a splay of the Himalayan Frontal thrust system, provides an excellent model of forward and lateral propagation of fault and associated folding in laterally opposite directions along the strike of the fault. It nucleates and extends in the northwest and southeast direction resulting in the diversion of the Dabka and Baur rivers respectively, leaving behind the signature of paleo-wind gaps through which these rivers streamed earlier during the recent past. The lateral propagation of Kaladungi Anticline resulted in the diversion of the Dabka River for about 10-12 km from east to west and this is justified by the existence of four Dabka River wind gaps DWG1, DWG2, DWG3 and DWG4. Similarly, the Baur River shifted for about 5-6 km from west to east leaving signatures of two Baur wind gaps BWG1 and BWG2. The existence of more than one windgap formed by the same river, however, is a strong validation of lateral propagation of fault and related folding. 
Potential of synthetic aperture radar wide swath acquisitions to map sea state variability of European seas
Authors: Maillard Lisa , Grouazel Antoine , Nouguier Frédéric , Accensi Mickael , Marquart Robin , Delouis Jean-Marc , Mouche Alexis
Published: March 2024

Copernicus Sentinel-1 Synthetic Aperture Radar (SAR) mission systematically acquires data in Interferometric Wide swath mode over European land and water. This study investigates the potential of this data processed into Level-1 (L1) Single Look Complex (SLC) to compute meaningful image cross-spectra over the ocean to retrieve ocean surface waves parameters. First, each L1 SLC is processed relative to a "tile'', a prescribed spatial division of the burst (a unitary acquisition sequence of Sentinel-1 TOPS mode) and SAR image cross-spectra are defined within the burst and between two adjacent bursts. Then, using a neural network approach based on SAR image cross-spectra and on the WaveWatch III® wave model, an algorithm is proposed to provide estimates of significant wave height, fractions of wave height due to wind sea, and mean wave period. As obtained, the algorithm yields to promising performances when validated against in situ and satellite data.
Unraveling the climate evolution on Mars and Earth with AI-driven surface mapping and explainable AI
Authors: Fanara Lida , Su Shu , Martynchuk Oleksii , Hauber Ernst , Schlegel Anastasia , Ludwig Jakob , Melching David , Hänsch Ronny , Gwinner Klaus
Published: March 2024

Our research leverages state-of-the-art deep learning techniques to automate surface mapping and continuous monitoring on planetary bodies. We are also developing tools to analyze the model uncertainty and decision-making in AI models with evaluation in our surface mapping projects and beyond.We focus on one of the solar system's most dynamic Earth-analog environment on terrestrial planets - Mars' northern polar region, a repository of the planet's climatic history within its extensive ice-layered dome. We detect small blocks [1] and their sources yielding a reliable method for monitoring mass wasting activity with valuable present-day erosion rate results [2].In parallel, we investigate and map polygonal patterns on both Earth and Mars to assess the global distribution of polygons and their potential as indicator for climate conditions and changes. On Earth, polygons are indicators of the volume of ground ice and provide insights into permafrost vulnerability to climate change. On Mars, similar young landforms could be linked to geologically recent freeze-thaw cycles. This would be conflicting with the current environment and would have implications for the recent hydrologic past of the planet. The distribution of polygonal ground on Mars can provide valuable information on the role of liquid water in the recent past by shedding light on the formation mechanism.We use AI models for automated surface mapping because they achieve highly complex decision-making. However, they are usually treated as Black-Box systems. To tackle this problem, we are developing software tools for analyzing model uncertainty and decision-making within an application-independent framework. Typical questions are why did the model produce exactly this response and how certain is it about the correctness of its results?References: [1] Martynchuk O. et al., 2024. EGU 2024. [2] Su S. et al., AGU 2023.
Framework for identifying large-scale Nature-Based Solutions for drought mitigation: regional application in Flanders 
Authors: De Trift Lien , Yimer Estifanos Addisu
Published: March 2024

Droughts are classified as the most expensive climate disasters as they leave long-term and chronic impacts on the ecosystem, agriculture, and human society. The frequency, intensity, and duration of drought events have shown a historical increase and are projected to escalate globally, continentally, and regionally in the future. Nature-based solutions (NBS) are highlighted as effective solutions to cope with the future impacts of these events. Until now, there has been a lack of a comprehensive suitability mapping framework that considers drought-specific criteria. To address this gap, a novel framework is introduced, targeting the identification of suitable areas for two drought-mitigating NBS types—detention basins and managed aquifer recharge—on a regional scale. This new framework incorporates diverse criteria to specifically address drought conditions. For example, by incorporating climate change scenarios for both surface and groundwater, it identifies suitable and sustainable locations capable of managing extreme drought events. Executed through Boolean logic at a regional scale in Flanders (Belgium), the framework's strict approach yields significant potential areas for detention basins (298.7 km²) and managed aquifer recharge (867.5 km²). Incorporating multi-criteria decision-making (MCDM) with the same criteria introduces a higher degree of flexibility for decision-makers. This approach shows a notable expansion across Flanders, varying with the level of suitability. The results underscore the highly suitable potential for detention basins (2840.2 km²) and managed aquifer recharge (2538,7 km²), emphasizing the adaptability and scalability of the framework for addressing drought in the region.
Groundwater Prediction in the Thames Basin, London, Using Temporal Fusion Transformer Models 
Authors: Ali Ali , Ahmed Ashraf , Abbod Maysam
Published: March 2024

Addressing Thames Basin aquifer complex dynamics in England, this study uses a Temporal Fusion Transformer (TFT) for groundwater level prediction. Our research combines extensive hydrological data with advanced machine learning suited to Thames Basin, where a complex network of rivers and streams substantially affects groundwater dynamics. Unlike previous studies, this research focuses on long-term forecasting with deep learning, offering a long prediction horizon. To rigorously examine the model performance and robustness on new, unseen data, we applied the walk-forward validation method and other matrices such as RMSE and R2 coupled with the Holdout technique. Our approach contrasts traditional Long-Short Term Memory (LSTM), Attention-based LSTM, and TFT, focusing on the basin’s aquifers, Chalk, Oolitic Limestone, and Lower Greensand. Whilst both LSTM models were optimised using the Bayesian technique, TFT was applied for its inherent capability in complex time series. Our methodology processed historical groundwater and rainfall data from 2001-2023, accounting for the potential lag in aquifer response to the proximity of the river system. The dataset served as training, validation, and holdout for each model, focusing on capturing the dynamic temporal fluctuation. The results clearly showed the superiority of the TFT model in all aquifer types compared to other models across all horizons 7, 30, and 60 days. In the 60 days, the best results were observed in the Chalk aquifer with RMSE of 0.04 and R2 of 0.97 in holdout validation. However, in Limestone and Lower greensand aquifers, the TFT showed RMSEs of 0.12 and 0.016 and R2s of 0.65 and 0.32, respectively. Traditional LSTM models demonstrated limited predictive power, with negative values in all aquifers, while Attention-based LSTM slightly improved the efficacy. This study highlights the potential of sophisticated machine learning in managing complex aquifers and predicting water tables.
Can AI be enabled to dynamical downscaling? Training Deep Generative Models to downscale ERA5 to high-resolution COSMO-CLM dynamical reanalyses over Italy 
Authors: Tomasi Elena , Franch Gabriele , Cristoforetti Marco
Published: March 2024

Downscaling techniques are one of the most prominent applications of Deep Learning (DL) in Earth System Modeling. A robust DL downscaling model can generate high-resolution fields from coarse-scale numerical model simulations, saving the timely and resourceful applications of regional/local models. Moreover, specific DL models can generate uncertainty information and provide ensemble-like pool scenarios, hardly achievable using traditional numerical simulations due to their high computational requirements. In this work, we present the application of deep generative models, namely a Generative Adversarial Network (GAN) and a Latent Diffusion model (LDCast, Leinonen et al., 2023), to perform the downscaling of ERA5 (Hersbach et al., 2018) data over Italy up to a resolution of 2km. The target high-resolution data used for training consists in the Italian high-resolution dynamical reanalyses obtained with COSMO-CLM (Raffa et al., 2021). The goal of the study is to show that recent advancements in generative modeling can learn to provide comparable results with numerical dynamical downscaling models, such as the COSMO-CLM model, given the same input data (i.e., ERA5 data), preserving the realism of fine-scale features and flow characteristics. The training and testing database is composed of hourly data from 2000 to 2020 (~184000 timestamps), and the target variables of the study are 2-m temperature and horizontal wind components. A selection of predictand variables from ERA5 is used as input to the DL models (e.g., 850hPa temperature, specific humidity, and wind). The generative models are compared with reference baselines, both DL-based (e.g., UNET) and statistical methods. Preliminary results are presented, highlighting the improvements introduced with this architecture with respect to the baselines. The results are evaluated by different quantitative verification scores: RMSE, predicted spectra, frequency distributions, and spatial distribution of errors. 
Multiscale experimental investigation of crystal plasticity and grain boundary sliding in rock salt using digital image correlation
Authors: Li Xinjie , Dimanov Alexandre , Bornert Michel , Hallais Simon , Gharbi Hakim
Published: March 2024

In the context of the global environmental crisis and the urgent need for energy transition and efficient energy storage solutions, salt caverns have gained attention as promising reservoirs for hydrogen. However, current literature predominantly focuses on deriving macroscopic constitutive relations, lacking crucial insights into the underlying physical mechanisms of deformation and damage active at various microscopic scales. This study addresses this gap by undertaking qualitative and quantitative investigations into the micro-mechanisms of rock salt, employing advanced micro-scale observation techniques. Natural rock salt from diverse mines and re-synthetic salts, produced through the cold compaction of grinded natural halite powder, are used to encompass a wide range of microstructural morphologies. Initial microstructure characterization involves SEM, EBSD, and CT, followed by classic uniaxial compressive tests coupled to optical microscopy monitoring. High-resolution images of the sample surface are continuously captured during testing, allowing for 2D full field measurements by subsequent application of digital image correlation techniques : the analysis of relative displacements of markers randomly distributed on the sample surface enables the retrieval of surface displacement fields and the calculation of the corresponding local strain fields over statistically representative domains. Segmentation of digital images and quantitative identification, specifically focusing on crystal slip plasticity and grain boundary sliding using an in-house computation program, reveal the complex local interactions of different micro-mechanisms. The estimation of the relative contributions of these mechanisms to global deformation all along the loading path, along with an analysis of the impact of salt grain size, provides insights into physically grounded micromechanical constitutive relations. These findings are essential for the safety assessment of industrial applications involving rock salt caverns with respect to short-term mechanical loading conditions relevant to daily hydrogen filling and withdrawal.
Structure, morphology and seismicity of the frontal part of a propagating fold-and thrust belt: The Holocene 123-km-long Kur Fault, Greater Caucasus, Azerbaijan 
Authors: Tibaldi Alessandro , Bonali Fabio , Pasquaré Mariotto Federico , Oppizzi Paolo , Tsereteli Nino , Havenith Hans , Babayev Gulam , Pánek Tomáš
Published: March 2024

We present the main features of the frontal structure, known as Kur Fault, of the Plio-Quaternary Kura fold-and-thrust belt in the Greater Caucasus (Azerbaijan). The Kur Fault has been analysed thanks to geological-structural and geomorphological surveys of its whole length, integrated by a relocation of instrumental seismicity, data on historical seismicity, new focal mechanism solutions, and ambient vibration measurements across the fault trace. The in-depth study of the frontal structure can: i) provide insights into the shallow propagation of a regional reverse fault, ii) contribute to a better understanding of the earlier stage of development of a young continent-continent collision, and iii) have implications for seismic hazard assessment because the area is seismically active and hosts the most important infrastructure for energy production in the country. The results show that the fault deforms the surface for a total length of 123 km. The shallow expression is given by four main scarp segments, with a right-stepping arrangement, which have different structural significance; they are represented by an alternation of fault-propagation folds, folds with offset frontal limbs, and shallow faulting. Analyses of the age of deformed deposits and landforms suggest activity from Mid-Late Miocene times to the Holocene. The fault attitude and its reverse kinematics are coherent with the Holocene and present-day state of stress, characterised by a N-S to NNE-SSW horizontal s1, suggesting the capability for seismic reactivation. Earthquake focal mechanism solutions indicate from pure reverse motions to transpressional kinematics in the area. Calculation of potential Mw indicates values in the range 7.5-7.9 if we consider its entire fault length, 6.1-7.2 if we consider the single segments.     
The Land-Atmosphere Feedback Initiative
Authors: Wulfmeyer Volker ,   The LAFI Team
Published: March 2024

The quality of weather forecasts, seasonal simulations, and climate projections depends critically on the adequate representation of land-atmosphere (L-A) feedbacks. These feedbacks are the result of a highly complex network of processes and variables related to the exchange of momentum, energy, and mass. Significant challenges persist in understanding processes and feedbacks, which this initiative will address.The Land-Atmosphere Feedback Initiative (LAFI) is an interdisciplinary consortium of researchers from atmospheric, agricultural, and soil sciences as well as from bio-geophysics, hydrology, and neuroinformatics proposing a novel combination of advanced research methods. The overarching goal of LAFI is to understand and quantify L-A feedbacks via unique synergistic observations and model simulations from the micro-gamma (» 2 m) to the meso-gamma (» 2 km) scales across diurnal to seasonal time scales.LAFI consists of a network of closely intertwined projects addressing six research challenges formulated as objectives and hypotheses on 1) alternative similarity theories, 2) the impact of land-surface heterogeneity, 3) partitioning evapotranspiration, 4) understanding entrainment, 5) synergistic characterization of L-A feedback, and 6) droughts or heatwaves potentially investigated by ad-hoc field observations. Collaboration across the twelve projects will be fostered by three Cross Cutting Working Groups on Deep Learning, Sensor Synergy and Upscaling, as well as the LAFI Multi-model Experiment. In this presentation, an overview of the LAFI research approach is given with particularly emphasis of the synergy of observations and modeling efforts substantiated by first results from the Land-Atmosphere Feedback Observatory (LAFO) at the University of Hohenheim in Stuttgart, Germany.
Poleward shift of the subtropical highs drives Patagonian ice fields mass loss
Authors: Noël Brice , van den Broeke Michiel , Lhermitte Stef , Wouters Bert , Fettweis Xavier
Published: March 2024

The Patagonian ice fields have been rapidly losing mass in the last decades, but little is known about the driving processes. Here we use state-of-the-art regional climate models to reconstruct the contemporary climate and glacier surface mass balance (SMB), i.e., the difference between snowfall accumulation and meltwater runoff, in the Southern Andes at 5 km spatial resolution for the period 1940-2022. Model outputs are further statistically downscaled to a 500 m grid that resolves SMB processes in high spatial detail. Our high-resolution SMB products show good agreement with both in-situ observations and GRACE/GRACE-FO satellite mass change measurements, when combined to solid ice discharge. We link recent glacier mass loss to an ongoing poleward shift of the subtropical highs that warms the ocean and atmosphere nearby Patagonian ice fields, in turn enhancing meltwater runoff.
Addressing Water Challenges in Southern Spain: A Comprehensive Assessment and Sustainable Management Approach
Authors: Baccour Safa , Berbel Julio , Gutierrez Carlos , Diaz-Cano Esther
Published: March 2024

Increasing climate-related water stress and growing water demand are challenging the goal of achieving food and water security in many basins around the world.. Addressing the problem requires the integration of sectoral policies based on interdisciplinary knowledge and sustainable management strategies. This study presents the development of an innovative and dynamic optimization framework that integrates a detailed representation of hydrological and technological constraints while accounting for the feedback between sectors (agriculture, urban, industrial, golf, and livestock). The hydroeconomic model has been applied in Axarquía (Spain) as a case study to evaluate the performance of water allocation and management among several users, determine the cost of water scarcity, and design sustainable water management interventions under future climate conditions. The policy analysis offers insights into the effects of alternative management strategies regarding cost of water supply from different water sources (including surface water diversion, groundwater pumping, non-conventional water production, and reservoirs). Our results highlight the potential of policy options for increasing water availability and suggest the most cost-effective and feasible options. The findings provide efficient water allocation plans between competing sectors, emphasizing the importance of using non-conventional water resources, such as desalinated water and wastewater, which help to save limited conventional resources and play an increasingly important role in meeting rising water demands. These critical results could help decision-makers to bring about efficient water allocation planning among sectors and advance resilience and adaptation to climate water stress. Axarquía’s issues and challenges light a path to relevance for other river basins internationally.
Site monitoring and activity detection of wind turbines with Planet and Sentinel-2 satellite data
Authors: Gärtner Philipp , Wehner Claudius , Siegismund Jan , Albert Johannes , Zschache Johannes
Published: March 2024

The ongoing energy transition presents us with the challenge of finding sustainable and efficient ways to generate renewable energy. In this context, wind energy plays a decisive role and contributes significantly to increasing the share of renewable energies in the energy mix. Strategic energy planning, effective repowering, decommissioning and the seamless integration of wind energy into the power grid require accurate location information of existing wind turbines. In this work, we present a) the precise, automated, Germany-wide identification and localization of wind turbines using high-resolution planetary data and b) an innovative approach to detect wind turbine activity using Sentinel-2 data. The detection of wind turbine activity is based on the different blade positions, including their shadow position, which is caused by slightly offset recording times of the spectral bands. The change is highlighted and classified using a Convolutional Neural Network. The presentation also discusses possible limitations and peculiarities of the methods used and emphasizes the relevance of remote sensing-based monitoring for the wind energy industry and environmental monitoring.
A novel in-situ cloud and aerosol imaging polarimeter for atmospheric research - Bridging the gap between satellite data and in-situ measurements
Authors: Schnaiter Martin , Hamel Adrian , Wagner Shawn , Järvinen Emma
Published: March 2024

The new-generation of satellites will revolutionize Earth observation with advanced sensors, including polarimetric observation capabilities like EUMETSAT's Metop-SG. Equipped with instruments like the Multi-Viewing Multi-Channel Multi-Polarisation Imaging (3MI), these satellites will offer unprecedented insights into the aerosol and cloud components of Earth's atmosphere. However, the indirect nature of satellite observations requires validation through in-situ measurements. In response, we are developing an in-situ cloud and aerosol imaging polarimeter, designed for operation in cloud chambers, at mountain-top stations as well as aboard research aircraft. This innovative approach aims to bridge the gap between satellite data and in-situ measurements, enhancing validation studies and ensuring the accuracy of next-generation satellite observations in climate change research.Our polarimeter features an innovative design, highlighting a high-resolution camera chip combined with a wide-angle lens for capturing laser light scattered by cloud and aerosol particles at a high angular resolution of better than 0.05° and for a wide backscattering angular range from about 101° to 169°. A directed laser beam is imaged over several meters at a specific observation angle in an open path arrangement. Light scattered from particles transforms into a line on the camera chip, with each pixel corresponding uniquely to a different scattering angle. The optical design incorporates an adjustable polarization filter set-up within the imaging system, enabling seamless measurement of the full Stokes polarization vector of the angular light scattering function. This advanced imaging polarimeter concept offers high accuracy in measuring cloud drop size distribution, as well as linear and circular polarization and depolarization ratios. Notably, our in-situ polarimeter is "active," utilizing a polarized laser beam, distinguishing it from the "passive" approach of satellite polarimeters relying on sunlight.The presentation will delve into the detailed concept of this innovative polarimeter, offering insights into its optomechanical design. Results from comprehensive optical simulations will showcase the expected measurement capabilities, concluding with findings from initial laboratory tests of the prototype instrument.
Petrological and geochemical characterization of the Golja Ignimbrite (Main Ethiopian Rift)
Authors: Langone Federica , Franceschini Zara , Avanzinelli Riccardo , Braschi Eleonora , Forni Francesca , Cioni Raffaello
Published: March 2024

The Plio-Pleistocene volcanism of the Main Ethiopian Rift (Ethiopia) is characterized by a bimodal distribution with abundant mafic and felsic compositions and rare intermediate magmas, a feature commonly known as the Daly Gap. The Quaternary activity is characterized by large explosive eruptions associated with caldera collapses that define a regional paroxysm of silicic and basaltic volcanism. The genesis of the evolved compositions and their relationship with the basalts still represents a matter of debate, with interpretations ranging from pure fractional crystallization to more complex scenarios involving magma mixing and crustal melting. Here, we present the first volcanological, petrological and geochemical characterization of a pyroclastic sequence, located in the Central Main Ethiopian Rift, the Golja Ignimbrite (GI). GI is a crystal-poor (
New insights into the relationship between mass eruption rate and volcanic column 
Authors: Aubry Thomas , Engwell Samantha , Bonadonna Costanza , Mastin Larry , Carazzo Guillaume , Van Eaton Alexa , Jessop David , Grainger Roy , Scollo Simona , Taylor Isabelle , Jellinek Mark , Schmidt Anja , Biass Sebastien , Gouhier Mathieu
Published: March 2024

Understanding the relationship between the mass eruption rate (MER) and volcanic column height is essential for both real-time volcanic hazard management and reconstruction of past explosive eruptions. Using 134 eruptive events from the new Independent Volcanic Eruption Source Parameter Archive (IVESPA, v1.0), we constrain bespoke empirical MER-height relationships for four measures of column height: spreading level, sulfur dioxide height, and two measures of top height, from direct observations and as reconstructed from deposits. These relationships show significant differences, and we discuss implications for their applications in ash dispersion forecasting and modelling volcanic climate impacts. The roles of atmospheric stratification, wind, and humidity remain challenging to detect across the wide range of eruptive conditions spanned in IVESPA, ultimately resulting in empirical relationships outperforming analytical scaling relationships and the Geneva 1-dimensional (1D) volcanic plume model accounting for atmospheric conditions. However, when excluding the IVESPA events with the highest uncertainties, the 1D model progressively outperforms the empirical MER-height relationship. Our findings highlight persisting challenges in constraining the MER-height relation and reinforce the need for improved eruption source parameter databases documenting uncertainties, as well as improved physics-based models.
Perspective on ice age Terminations from absolute chronologies provided by global speleothem records
Authors: Kaushal Nikita , Stoll Heather , Pérez-Mejías Carlos
Published: March 2024

Glacial Terminations represent the largest amplitude climate changes of the last several million years.  Over ~ 10 ky timescale, large northern hemisphere ice sheets retreat and sea level rises, and atmospheric CO2 and global temperatures make a full transition from glacial to interglacial levels.  Several possible orbital-insolation triggers have been described to initiate and sustain glacial Terminations, and feedbacks between ice sheet retreat, ocean circulation and ocean carbon storage are invoked to explain the unstoppable progression. Because of the availability of radiocarbon dating, the most recent termination (TI) has been extensively characterized. Yet, it is widely discussed whether this sequence of feedbacks and millennial events, and rate of warming is recurrent over previous Terminations or is unique.  Beyond the limit of radiocarbon dating, the chronologies of climate records from ice and marine cores are often developed by tuning to orbital parameters which limits their use in understanding climate dynamics, particularly the response to orbital forcing.Speleothems provide absolute age control and high-resolution proxy measurements. This archive therefore provides unique records of climate change across Terminations, and additionally may provide the opportunity to tune ice and marine core archives.  However, speleothem climate signals are encoded in a number of proxies. Unlike proxies in other archives like ice or marine cores, the climatic interpretation of a given proxy can vary quite significantly among different regions.In this study, wesynthesize the available speleothem records providing climate information for Terminations: TII, TIII, TIV and TV.
present the records based on the aspect of climate encoded in the available records.
examine the effects of different ice volume corrections on the final climate proxy record.
evaluate whether there are leads and lags in the manifestation of Terminations across different aspects of the climate systems and different regions.
we speculate on suitable tuning targets among marine and ice core proxies, and discuss what model outputs maybe most suitable for comparison.
Apparent Aging and Rejuvenation of Terrestrial Organic Carbon Along the River-Estuary-Coastal Ocean Continuum
Authors: Yu Meng , Eglinton Timothy , Hou Pengfei , Haghipour Negar , Zhang Hailong , Wang Zicheng , Zhao Meixun
Published: March 2024

The balance between remineralization and sedimentary burial of terrestrial organic carbon (OCterr) in large river-dominated marginal seas influences atmospheric CO2 inventory on a range of timescales. Here we systematically investigate the evolution of OCterr along the river-estuary-coastal ocean continuum for three fluvial systems discharging to the Chinese marginal seas. The 14C-depleted characteristics of bulk OC and molecular components of riverine suspended sediments and marine sediments suggest that the Chinese marginal seas are a significant sink of pre-aged OCterr. Lower plant-wax fatty acid 14C contents suggest selective degradation of labile OC within estuaries, resulting in apparent aging of OCterr, followed by an apparent rejuvenation in OCterr in shelf sediments, the latter likely reflecting inputs from proximal sources that contribute younger OCterr. This selective degradation, aging and rejuvenation of OCterr along the continuum confounds the use of plant wax lipid 14C to constrain lateral transport times, and sheds light on more complex OCterr dynamics in marginal seas.
Exploring the autumn phenology of European beech forests: a comparative analysis of ground-based and satellite observations
Authors: Cesaretti Lorenzo , Ferrara Carlotta , Corona Piermaria , Bajocco Sofia
Published: March 2024

Vegetation phenology is closely linked to the functioning of multiple aspects of forest ecosystems and is regulated by a complex interaction between climatic and environmental factors. In particular, the end of the growing season has proven to be very sensitive to extreme weather events, leading to alterations in the regular physiological behaviour of forests. Autumn phenology represents a little-explored season due to the highly variable response of forests to environmental factors. This work aims to investigate late-season dynamics by comparing ground-based and satellite observations in European beech forests. The objectives of this research are: (i) quantify the temporal discrepancy between phenology obtained from ground-based observations (PEP725 stations) and satellite-derived data (MODIS EVI time series); (ii) assess the influence of the main biophysical factors, i.e. latitude, elevation, total annual precipitation and mean annual temperature, on the mismatch. The results identified key end-of-season metrics, distinguishing different stages during the season that were affected differently by biophysical factors, such as temperature and precipitations. This study highlights the complexity of late-season phenology, emphasizing the crucial role of remotely sensed phenometric analysis compared to ground-based observations, revealing a fundamental contribution to understanding of late-season phenology in the context of climate change.
Fine root longevity and biomass production in boreal peatlands
Authors: Minkkinen Kari , Laiho Raija , Salomäki Jaana
Published: March 2024

Drainage for forestry alters the carbon (C) dynamics and stocks of peatlands. After drainage soil C stocks usually decrease, because of increased soil organic matter (SOM) decomposition, while the C stocks in vegetation (trees) increase, because of increased primary production. However, sometimes also the soil C stocks have been reported to have increased after drainage, despite of increased SOM decay. This observation can only be explained by the increased above- and belowground litter production.  Above ground litterfall can be easily measured with litter collectors, and there is a rather good understanding of its dynamics and magnitude in forested peatlands. However, the rate of below ground litter input through the growth and death of fine roots, has remained uncertain, because of methodological challenges. One laborous but plausible method to estimate belowground litter input is the minirhitzotron-method, in which the lifetime, i.e., longevity (and its complement: turnover) of roots is measured with repeated photographing of roots through a transparent tube inserted into the ground. With the measurements of in situ root biomass, the root production rate can then be calculated as turnover rate × biomass.We measured the longevity and biomass of fine roots (d
Advancing Physical Interpretability of Arctic Sea Ice Dynamics through Automatic Feature Selection
Authors: Bianchi Luca , Sangiorgio Matteo , Materia Stefano , Iovino Doroteaciro , Castelletti Andrea
Published: March 2024

Modelling Arctic sea ice dynamics has proven to be a successful application for machine learning, leveraging its ability to generate accurate and computationally efficient forecasts. Nevertheless, prevailing limitations lie in the need for physical interpretability and the inability to unveil the dynamics and interdependencies between relevant ice-related variables and their drivers. In this study, we provide a two-step framework designed to combine the high accuracy and computational efficiency characteristics of machine learning while ensuring high interpretability.The first step of our framework entails time series clustering to identify subregions that are homogeneous with respect to the spatiotemporal variability in the considered variable and obtain the barycentric time series of each cluster. We then use an advanced feature selection algorithm, the Wrapper for Quasi Equally Informative Subset Selection, that identifies neural predictors, specifically Extreme Learning Machines, to forecast the future evolution of sea ice. It then provides the most relevant set of inputs necessary for accurately describing the evolution for each cluster.Our investigation focuses on the monthly evolution of sea ice thickness and uses data from the Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS). Other PIOMAS variables (i.e., sea ice concentration, snow depth, sea surface temperature, and sea surface salinity) as well as observed discharge from five major Arctic rivers (i.e., Ob, Yenisey, and Lena in Asia, Mackenzie and Yukon in North America, provided by the Arctic Great Rivers Observatory discharge dataset) are considered as potential driving factors. Our results indicate the pivotal role of past sea ice thickness values, since the forthcoming state of sea ice seems to be influenced by both the current situation and historical trends and periodicity. Sea surface salinity in the open Arctic Ocean is highly persistent, and therefore is not used by the algorithm to explain the sea ice evolution. On the other hand, the Arctic rivers’ flows are more representative of the processes occurring in the clusters along the coast. Finally, the interaction between sea surface temperature and snow depth controls the interplay between ice formation and melting, and therefore plays a significant role in shaping the sea ice evolution in the short term.Our framework aims to advance our comprehension of the complex physical processes governing sea ice thickness evolution in the Arctic region. Moreover, its effectiveness in uncovering sea ice related processes is expected to further improve with the inclusion of additional input variables and, possibly, of a longer data record.
Sub-Monthly Mass Change Signal in Greenland from GRACE-FO Laser Interferometry Data
Authors: Jenny Barbara , Jepsen Marcus , Simonsen Sebastian Bjerregaard , Forsberg René , Jensen Tim Enzlberger
Published: March 2024

GRACE and GRACE-FO have proven valuable for monitoring the health of ice sheets by showing seasonal mass changes along with the decadal trends of mass loss. Two years stand out in the Greenland ice sheet mass loss record with record melt: 2012 and 2019. On the West coast of Greenland, the ice mass fluctuations act on remarkably short time scales during these events, as evident at Ilulissat isbræ, which nearly doubled its ice speed in just one week. Here, we study if these sub-monthly ice mass change variations can be measured using GRACE-FO line-of-sight measurements.It has been shown several times that using dynamic orbits and Laser Ranging Interferometer (LRI) data, one can calculate residual Line-of-sight gravity signals. This method was primarily used to study hydrological signals such as storm surges or heavy rainfall. In this study, we focus on ice mass changes in Greenland, and we compare these GRACE-FO measurements to the expectation based on the monthly gravity field and the signal from mass change based on IceSat2 data for 2019-2021.
Petrogenesis and tectonic implications of the late Triassic gabbro in southern East Kunlun Orogenic Belt, northern Tibetan Plateau
Authors: Zhang Bin , Dong Yunpeng , Sun Shengsi , He Dengfeng
Published: March 2024

        The East Kunlun orogenic belt represents a typical accretionary orogenic belt and has undergone an evolutionary process from the Proto-Tethys to the Paleo-Tethys oceans. The Late Triassic period witnessed the East Kunlun transitioning into the post-collisional extensional tectonic setting. However, there is ongoing debate regarding the dynamic mechanism responsible for the post-collisional extension. This study conducts the lithological, geochronological, and geochemical characteristics of the Yeniugou gabbros to shed light on the dynamic mechanism. Zircon geochronology suggests that the gabbros formed in the Late Triassic, ca. 207–209 Ma. Furthermore, the positive εHf (t) values (0.1–5.7), the relatively high values of Mg# (42.2–59.4), as well as the elevated contents of the compatible element (V, Cr, Co, Ni), suggest a mantle source with the contributions from asthenospheric mantle constituents. Additionally, gabbros are enriched in LREE and LILEs (Rb, Ba, Th, U, Sr), and depleted in HFSEs (i.e., Nb, Ta, Ti, Zr), suggesting the incorporation of arc-related enrichment components. The higher values of La/Sm, Th/Yb, Th/La, and lower values of Ba/Th, Ba/La, and Lu/Hf indicate that the enriched components are derived from the melting of the terrigenous sediment. The higher Zr/Y ratios, Nb contents, moderate Zr, Y contents, and the positive correlation between clinopyroxene Alz and TiO2, imply that these rocks were formed within an extensional tectonic setting, where upwelling of asthenospheric mantle caused partial melting of metamorphosed lithospheric mantle. Our new investigations support the interpretation that E-KOB experienced the thickening lithospheric delamination during the Late Triassic.
A time-dependent non-asymptotic statistical analysis of extreme precipitation events
Authors: Pesce Matteo , Dallan Eleonora , Marra Francesco , Borga Marco
Published: March 2024

Time-dependent precipitation frequency analyses were often hampered by the availability of relatively short data records, which result in large uncertainty in the estimation of extremes. The recently developed non-asymptotic statistical methods, based on fitting ordinary events rather than extreme events only, represent a potential solution to the problem of data scarcity and are finding wide application in literature under assumptions of stationarity. Recent studies investigated the use of non-asymptotic methods under non-stationary conditions (e.g., Vidrio-Sahagún and He, 2022) and advocated their use over other methods for non-stationary frequency analysis of extreme precipitation. In this study we formalize a non-stationary time-dependent approach for the statistical analysis of multi-duration precipitation extremes using simplified metastatistical extreme value (SMEV) approach. The study focuses on a catchment in the Eastern Italian Alps, where trends in extreme precipitation where reported (Dallan et al., 2022) and which was impacted by the exceptional Vaia event in 2018. We provide an estimation of extreme return levels of precipitation in six stations in the neighborhood of the catchment and compare them with precipitation maxima observed during Vaia storm. The results show that using a non-stationary left-censored Weibull distribution, with both scale and shape parameters linearly dependent on time, allows to properly describe the observed trends of intense precipitation for different durations. Our results suggest that the probability of observing events like Vaia increased over the past decades, leading to the need for updating local adaptation measures. References:Dallan, E., Borga, M., Zaramella, M., & Marra, F. (2022). Enhanced summer convection explains observed trends in extreme subdaily precipitation in the eastern Italian Alps. Geophysical Research Letters, 49(5), e2021GL096727.Vidrio-Sahagún, C. T., & He, J. (2022). Hydrological frequency analysis under nonstationarity using the Metastatistical approach and its simplified version. Advances in Water Resources, 166, 104244.
Cloud thermodynamic phase from spectral and multi-angle polarimetric imaging with specMACS
Authors: Weber Anna , Pörtge Veronika , Zinner Tobias , Mayer Bernhard
Published: March 2024

We present a method to retrieve cloud thermodynamic phase from multi-angle polarimetric and spectral imaging. Spectral absorption differences between water and ice in the near infrared are commonly used to discriminate between liquid, mixed, and ice clouds. For example, the spectral slope between 1500 and 1700 nm increases with decreasing liquid cloud fraction. These methods are very sensitive to small amounts of ice in liquid clouds. On the other hand, the polarization signal of clouds shows different features depending on the cloud thermodynamic phase. The cloudbow is formed by single scattering on liquid cloud droplets. Observation of the cloudbow indicates the presence of liquid water while its absence indicates pure ice clouds. In addition the slope of the Q component of the Stokes vector for scattering angles in the range of 60 to 100 degree depends on the partitioning between liquid and ice phase. The polarimetric method is much more sensitive to small amounts of liquid water compared to the spectral method and represents cloud thermodynamic phase at cloud top. In addition, polarization is dominated by single scattering and thus does not suffer from 3D radiative effects. Both methods are applied to data of the airborne hyperspectral and polarized imaging system specMACS measured during the HALO-(AC)3 campaign. specMACS provides wide-field and high spatial resolution data with a horizontal resolution down to a few 10m. By a combination of the spectral and multi-angle polarimetric observations we will retrieve cloud thermodynamic phase partitioning of single layer mixed-phase clouds and investigate spatial and temporal scales of phase transitions in low-level arctic mixed-phase clouds.
Precipitation impacting upper-ocean currents: an analysis using a km-scale Earth System model
Authors: Segura Hans , Peinado Angel , Bastin Swantje , Winkler Marius , Schevchenko Rodomyra , Dragaud Ian , Patruri Divya
Published: March 2024

In this study, we assess the impact of precipitation on the ocean current acceleration using an Earth System model resolving deep convection and ocean eddies using a horizontal grid spacing of 5 km. Punctual studies using observations show that precipitation events with intensities higher than 24 mm d^-1 could impact the upper-ocean dynamics. Basically, the increase in buoyance flux equals half buoyancy resulting in the absorption of shortwave radiation (200 W m-2) under clear sky conditions. Due to the spatial sparse of observational sites, there is still the question of whether this number holds only in specific locations. With a grid spacing of 5 km, the simulation shows that precipitation events in the tropical Atlantic with a mean intensity greater than 20 mm d-1 impact tremendously in the stratification due to salinity in the upper ocean with two consequences. First, the mixed layer depth shallows, even in cases with strong wind forcing. Second, the momentum trapped in this shallow layer accelerates the surface currents. This is also accompanied by an increase in the turbulent kinetic energy in the mixed layer depth. These results point to the fact that precipitation, in particular in the deep tropics, could impact the upper ocean dynamic.
The study on Digital Twins in Managing Water-Energy-Food Sectors in South Africa 
Authors: Ardakanian Atiyeh , Saeed Nagham , Moyo Hloniphani , Mudzielwana Rabelani
Published: March 2024

The study on Digital Twins (DT) in South Africa emphasizes DT's role in enhancing the efficiency of management and governance within the Water-Energy-Food nexus. By integrating data across energy, agriculture, and water sectors, DT provides a more cohesive and informed approach to decision-making where various stakeholders with multiple interests are involved. This integration enables streamlined governance processes and optimal resource utilization. Currently, governance in South Africa's water, energy, and food sectors is characterized by a mix of state and private involvement. The energy sector is overseen by the Department of Mineral Resources and Energy and includes state-owned entities, alongside private independent power producers and regulatory bodies. In agriculture, the Department of Agriculture, Land Reform and Rural Development plays a key role, with additional input from various agricultural bodies and NGOs. Water rights are state-owned, managed by the Department of Water and Sanitation, and regulated through licenses, with local management by water boards and municipalities. The land is a mix of private and state ownership, with a focus on agricultural development and reform. By understanding the priorities and influences of different groups, anticipating conflicts, and fostering cooperation, through DTs, we can ensure that initiatives for environmental conservation are more widely successful. 