bluuebunny/crossref_metadata_2025 huggingface dataset:
Melt detection from SMOS enhanced resolution brightness temperatures on the Antarctic and Greenland ice sheets
Authors: Zeiger Pierre , Picard Ghislain , Richaume Philippe , Rodriguez Fernandez Nemesio , Mialon Arnaud
Published: March 2024

The Soil Moisture and Ocean Salinity (SMOS) mission has been providing surface brightness temperatures (TB) at L-band since 2010. These measurements feed geophysical applications over the ice sheets including melt detection. The synergy between SMOS and other sensors operating at higher frequencies such as AMSR2 is furthermore promising to give insights on the percolation of meltwater in the snowpack and the presence of firn aquifers. However, most of the algorithms currently use the SMOS Level 3 (L3) gridded data which suffer from a coarse spatial resolution. To overcome this issue, we developed a new SMOS enhanced resolution TB dataset over Antarctica and Greenland which is further used to detect melt. The resolution enhancement process is based on the radiometer version of the Scatterometer Image Reconstruction (rSIR) algorithm which was previously successfully applied to SSM/I, SSMIS, AMSR and SMAP. Our methodology also takes advantage of the multi-incidence nature of SMOS measurements to use information with the best native resolution, i.e. low-incidence measurements (15-40°). We evaluated the effective spatial resolution to be ~30 km for the new SMOS enhanced TB maps. It is twice finer than the spatial resolution of the conventional SMOS L3 dataset (~60 km). Finally, a state-of-the-art melt detection algorithm was applied to both the enhanced resolution and the conventional L3 datasets. The new product unravels many localized melt patterns that were not detected using the SMOS L3, especially near the grounding lines of Antarctic ice shelves, due to smoothing of the TB between melting and non melting area. We also identify a clear aquifer signature over the ~25 km wide northern George 6 ice shelf in the Antarctic Peninsula thanks to the gain in resolution. The new SMOS enhanced resolution TB and melt products are posted on the same 12.5 km polar stereographic grid and are comparable to AMSR-E and 2 in terms of spatial resolution to facilitate further synergetic use of multi-frequency passive microwave datasets.
Future projection of East Asian Summer Monsoon precipitation under 1.5°C, 2°C, and 3°C global warming levels
Authors: Sun MinAh , Sung Hyun Min , Kim Jisun , Lee Jae-Hee , Shim Sungbo , Byun Young-Hwa
Published: March 2024

The East Asian summer monsoon (EASM) is an influential climate system that contributes to approximately 70% of the annual precipitation in the Asia region. Extensive research has been conducted on monsoon changes in response to future climate. In this study, we analyzed the characteristics of the EASM considering specific global warming level (GWL) using Coupled Model Inter-comparison Project 6 (CMIP6) simulations. The 30 CMIP6 models effectively captured the migration of the monsoon in present-day (PD), showing a pattern correlation coefficient of 0.91, which represents an improvement over values reported in previous studies. Dividing the monsoon period into P1 (first primary peak; 33-41 pentad) and P2 (from P1 to the withdrawal; 42-50 pentad), the frequency and amount of weak to moderate precipitation rates are predominantly higher in P2, while the frequency and amount of moderate to extreme precipitation rates are notably higher in P1. The CMIP6 models project a significant increase in precipitation under a warming climate, accompanied by a longer duration due to earlier onset and delayed termination. Under the three GWLs, the projected precipitation frequency decreases below moderate precipitation rates, while it significantly increases above strong precipitation rates. Additionally, the precipitation tendencies in both P1 and P2 are similar to those of the total period, with significant changes evident at the 3.0 °C GWL. These precipitation changes are associated with an increase in precipitation amount above the 97th percentile and influence the future changes in the EASM under a warmer climate. 
Machine learning implementation for mapping irrigated areas at fine temporal and spatial resolutions in the Limpopo River Basin 
Authors: Kiala Zolo , Matheswaran Karthikeyan , Garcia Andarcia, Mariangel , Dickens Chris
Published: March 2024

Most of the global available freshwater for food production is utilized for irrigation. Irrigation expansion is crucial for agriculture production as it can increase crop yields and be a dependable adaptation measure against climate change. Accurate information on the spatial extent of irrigated areas and their dynamic shifts is therefore essential for efficiently managing already pressured water resources. The multiplicity of remotely sensed data sources and state-of-the-art machine techniques offer new avenues for producing more accurate irrigation maps. This study presents the results from a monthly monitoring framework for fine-scale mapping of irrigated areas in the Limpopo River Basin. The proposed framework uses high to moderate-resolution earth observation data, the extra-tree classifier, and a series of land cover masks in differentiating rain-fed and irrigated areas. We found that the area of irrigated land during the dry season in 2021 varied from 356589 ha to 612738 ha between and September. The overall accuracy of classified maps varied from 98 to 100%.  The proposed framework offers an automatic and replicable cost-effective means of mapping irrigated areas using Google Earth engine, multisource data, and machine learning algorithms. 
Development of monitoring techniques for Urban flood damage
Authors: Lee Ki-Won , Lee Jongseok , Yoon Jooyeong
Published: March 2024

The frequency and extent of damage from urban flooding are increasing more and more due to rapid urbanization and climate change. The Dorimcheon Stream drainage Basin, a tributary of the Han River in Seoul, is one of the areas prone to frequent flooding during the flood season. When heavy rain occurs and the water level of the Han River rises, the water that was discharged into Dorimcheon through the Storm Sewer System cannot be drained and rather flowed back. In order to manage urban flooding that occurs in the Dorimcheon Stream drainage Basin, it is necessary to measure the water level at the confluence, the water level at the urban storm drain system and at roads in the flood monitoring area. There are many water level observation stations in the Han River, so anyone can easily check water level changes in real time. However, in the Dorimcheon stream basin, it is necessary to install other monitoring devices to monitor changes in water levels in storm drains or roads. In this study, an IOT-based water level gauge which is capable of real-time monitoring for storm drains and roads were researched and developed to monitor urban flooding in order to contribute to quick decision-making during urban flood forecasting and warning. It is expected that the developed monitoring device will be installed at a number of points, and use analysis of the acquired data, it will be possible to manage damage from urban flooding more scientifically and effectively. Keywords : Urban flood, Water level gauge, real-time monitoring Acknowledgement : This work was supported by Korea Environment Industry & Technology Institute(KEITI) through R&D Program for Innovative Flood Protection Technologies against Climate Crisis Project, funded by Korea Ministry of Environment(MOE)(2022003470002)
Causes, consequences and implications of the 2023 Lake Rasac GLOF, Cordillera Huayhuash, Peru
Authors: Emmer Adam , Vilca Oscar , Salazar Checa Cesar , Li Sihan , Cook Simon , Pummer Elena , Hrebrina Jan , Haeberli Wilfried
Published: March 2024

Glacierized Peruvian mountain ranges are experiencing accelerated glacier ice loss, including the second highest mountain range – Cordillera Huayhuash – which has lost about 40% of its glacier area (deglaciated area of approximately 34 km2) since the 1970s. The exposure of a new land is associated with various processes including the formation and evolution of glacial lakes, changing stability conditions of mountain slopes, and rapid mass movements. In this study, we integrate the analysis of meteorological data, remotely sensed images and field observations in order to document the most recent large mass movement-induced glacial lake outburst flood (GLOF) from moraine-dammed Lake Rasac (February 2023). We found that the triggering mass movement (the failure of Rasac arête ridge with an estimated volume of 1.1 to 1.5 ∙ 106 m3) occurred from the frozen rock zone with cold, deep-reaching permafrost and was preceded by several small magnitude precursory events. The stability reduction of the frozen rocks in the detachment zone most likely relates to deep warming, but not to critical conditions of warm permafrost with unfrozen water. Further, we describe the surprisingly short-distanced process chain (attenuated by the Lake Gochacotan located 3.5 km downstream from the detachment zone) and analyze the transport of large boulders with the use of hydrodynamic modelling, revealing that flow velocities > 5 m/s must have been reached in case of translational motion and > 10 m/s in case of rotational motion of the largest transported boulders (diameter > 3.5 m). This study helps us to understand (i) mechanisms, amplification and attenuation elements in GLOF process chains; and (ii) altering frequency-magnitude relationships of extreme processes in rapidly changing high mountain environments on regional scale (both large magnitude rockfalls and GLOFs). Considering the recent Peru-wide GLOF inventory published in 2022, this event corroborates the assumption of increasing frequency of large mass movement-induced GLOFs originating from warming permafrost in recent decades. 
Achieving net zero greenhouse gas emissions critical to limit climate tipping risks
Authors: Högner Annika (Ernest) , Möller Tessa , Schleussner Carl-Friedrich , Bien Samuel , Kitzmann Niklas H. , Lamboll Robin D. , Rogelj Joeri , Donges Jonathan F. , Rockström Johan , Wunderling Nico
Published: March 2024

Under current emission trajectories, at least temporarily overshooting the Paris global warming limit of 1.5 °C above pre-industrial levels is a distinct possibility. Permanently exceeding this limit would substantially increase the risks of triggering several climate tipping elements with associated high-end impacts on human societies and the Earth system. It is essential to assess this risk under emission pathways that temporarily overshoot 1.5 °C. Here, we investigate the tipping risks associated with a number of policy-relevant future emission scenarios, using a stylised Earth system model that comprises four interconnected core tipping elements. Assessing tipping risks in the year 2300, we find a non-linear increase for overshoots that exceed 1.8 °C peak temperature or persist above 1.5 °C beyond the end of the 21st century. Scenarios following current policies or pledges lead to high tipping risk of 30% (median) and more, with uncertainty from climate sensitivity and carbon-cycle feedbacks translating to large uncertainties in tipping risk (45% and more) for these scenarios. Further, we show that on multi-century timescales achieving and maintaining at least net-zero greenhouse gas emissions is paramount to minimise tipping risks. Our results underscore that stringent emission reductions in the current decade in line with the Paris Agreement 1.5 °C limit are critical for planetary stability.
Near vent seismicity at the Tour Eiffel vent site, Lucky Strike hydrothermal field, Mid-Atlantic Ridge
Authors: Bohidar Soumya , Crawford Wayne , Cannat Mathilde
Published: March 2024

Intense discharge of high temperature fluids through focused vents at black smoker hydrothermal fields creates local entrainment of cold seawater into the shallow sub-seafloor. This secondary hydrothermal circulation generates lower temperature diffuse vents that surround the black smokers, carry a large part of the total hydrothermal heat flux, and facilitate mineral precipitation in the substratum. Pontbriand and Sohn (2014) constrained this secondary circulation beneath the Trans-Atlantic Geotraverse (TAG), by characterizing shallow microearthquakes which were located by a small ~200 m aperture short-period Ocean Bottom Seismometer (OBS) network. These microearthquakes were proposed to have been triggered by reaction-driven cracking in response to anhydrite precipitation from heated seawater in the secondary circulation system.To detect possible shallow microearthquakes associated with the secondary circulation at the Tour Eiffel (TE) vent site, a small-scale ~150 m aperture 4 hydrophones network was deployed in 2016 as part of the EMSO-Azores observatory. TE is the largest vent site of the Lucky Strike hydrothermal field. It has a massive ~15 m high sulfide edifice, bearing several black smokers and surrounded by diffuse flow areas. The total heat flux, including both discrete and diffuse venting, from the TE vent site is estimated to be at least 20 MW, with more than 95% of the heat coming from diffuse venting.The first one year of data (September 2016 - September 2017) recorded by the hydrophone network includes shallow near vents events, whale songs and earthquakes originated outside the network. We therefore developed criteria based on waveform characteristics, number of phases, frequency spectra and synthetic waveform modelling to select only the shallow microearthquakes. We detected only 740 shallow microearthquakes, yielding a seismicity rate of only ~3 events/day and an average local magnitude of -2.48. The number of shallow events, and their magnitudes, are much smaller than those documented beneath the TAG hydrothermal mound (~ 243 events/day with average local magnitude = -0.95). The small number of shallow microearthquakes detected near TE over the one-year survey suggests that heating of entrained seawater and anhydrite precipitation are less prevalent than at TAG. This hypothesis is supported by time-series analysis of diffuse fluid samples, which mostly show no chemical evidence for anhydrite precipitation. It is also consistent with the TE vent site being smaller and having a lower estimated heat flux compared to the TAG mound (~1 GW).
Effects of temperature fluctuations on tidally-influenced coastal unconfined aquifers
Authors: Pu Li , Yu Xiayang , Xin Pei
Published: March 2024

Temperature has been found to play an important role in controlling groundwater flow and salinity distribution in coastal aquifers. However, previous studies focused on the effects of fixed temperature. In nature, both land surface temperature and seawater temperature fluctuate seasonally. The yearly fluctuation ranges of land surface and seawater temperatures can commonly reach 30°C. These surface temperature signals could propagate into coastal aquifers and change the temperature distribution in coastal aquifers. This may further induce seasonal variations in groundwater flow and solute transport processes. This research aims to investigate the effects of seasonal fluctuation in land surface and seawater temperatures on salinity distribution and water exchange in coastal unconfined aquifers subject to semi-diurnal tide. A numerical model, SUTRA-MS, is used to simulate the variably saturated and density-dependent groundwater flow coupled with salt and heat transport. Salt mass stored in the aquifer and water fluxes across the aquifer-ocean interface are used to evaluate the effects. Sensitivity analyses of fluctuation amplitude of temperature and tidal amplitude are also conducted. Finally, we discuss the implications of these results for nearshore biogeochemical processes and for accurate assessment of submarine groundwater discharge.
Quantifying the resistance of protective mixed-forest against natural hazards in the Pyrenees
Authors: Gómez García Paula , Madrigal-González Jaime , Arriaga Francisco , Robredo José Carlos , Tejedor Ernesto , Ballesteros-Cánovas Juan Antonio
Published: March 2024

In mountain areas, extreme weather events can trigger hydrogeomorphological processes (HGEs), such as torrential floods, snow avalanches, landslides or rockfalls. To mitigate the risks associated with these natural hazards, ecosystem services based risk reduction (Eco-DRR) approaches can be applied. In an Eco-DRR scheme, vegetation plays an important role, not only in reducing the probability of occurrence, but also in minimizing its impact providing natural barriers that limit the propagation of flow and energy. Understanding how the vegetation resists such events within a given forest stand is relevant for designing better forestry practices and maximizing the protective role of the forest. Here we focus on quantifying the mechanical resistance of trees subjected to HGE processes considering two potential failure modes, namely tree overturning and stem breakage. To this end, we perform pulling tests on 53 trees of two main species (Abies alba Mill. and Fagus sylvatica L.) growing on two plots (Gourzy forest – France and Arañones Forest – Spain) in the Pyrenees. We also collected structural and neighborhood characteristics of trees and forest stands and carried out dendroecological studies on selected trees. Both areas have a similar soil type (sandy soil - dolomites and calcarenites) composed of limestone, marl, clay and sandstone, and are affected by recurrent snow avalanches and rockfalls. Using a structural equation model (SEM) statistical framework, we test whether mechanical capacity is determined by either functional traits (i.e. species, tree growth, diameter and height) or structural traits (i.e. tree density, tree structure and slenderness). Our results suggest that forest competition modifies the mechanical capacity of trees through two pathways involving both functional and structural traits. Overall, functional traits condition the individual stiffness parameter of trees, whereas structural traits are mostly related to changes in elastic modulus. These results shed light on the behavior and plasticity of both species in avalanche and rockfall events, revealing better adaptations depending on certain allometric and structural traits, and providing relevant information for foresight on management strategies of forests with a protective role against natural hazards in the face of climate change.
Estimation of annual grassland yields with Sentinel-2 time series
Authors: Reinermann Sophie , Schucknecht Anne , Gessner Ursula , Asam Sarah , Kiese Ralf , Kuenzer Claudia
Published: March 2024

Grassland ecosystems shape the landscape in large parts of Germany and provide numerous services that are relevant for the carbon cycle, water quality and biodiversity, apart from being the main source of fodder for the dairy and meat industry. Annual yields between grasslands vary strongly because their productivity depends on the management and environmental conditions. Information on grassland yields are not freely and extensively available in Germany but would be relevant for comprehensive assessments of grassland ecosystem services including the impact of extreme events on yields. With satellite remote sensing, grassland productivity and yields can be extensively and multi-temporally estimated. Within our project (SUSALPS, https://www.susalps.de/en/), grassland yields are estimated in a grassland-dominated area in southern Germany using ground-truth measurements of above-ground biomass and Sentinel-2 time series data. Field data was collected on 12 differently used grassland parcels in the region in 2019-2021. We aim to overcome limitations of previous research – caused by the heterogenous nature of grasslands due to varying use intensities in Germany – by including management information and a large gradient of field samples trough multiple measurements throughout the vegetation growth period into the modelling. We tested empirical model based on the field and accompanying Sentinel-2 data (n=74) to estimate grassland biomass. The best model was applied to all available Sentinel-2 scenes in the region in 2019. Random Forest and Artificial Neural Network models showed the highest accuracy (R²cv = 0.7). A novel input feature was the mowing date which is available as 6-year dataset (Reinermann et al. 2022 & 2023). Next, the multi-temporal biomass estimations are aggregated to annual yield estimates to enable spatially discrete and multi-annual yields are estimated and compared (2018-2023). First results show that the inclusion of mowing date information supports the reliable estimation of grassland yields and its assessment on fine spatial scale substantially. In the future, the results are coupled with modelled plant biodiversity information to gain a complementary picture on grassland ecosystem services.
Analysis of some gully control techniques for the conservation of olive cropped landscapes in Southern Spain
Authors: González Garrido Paula , Peña Adolfo , Vanwalleghem Tom , Giráldez Juan Vicente
Published: March 2024

The current evolution of climate in Southern Europe, apparently enhances the frequency and persistence of rainless spells, with interspersed short and intense rainfall events. Both circumstances exacerbate the soil erosion episodes, particularly in the olive cropped landscapes, with the consequent risk of soil productivity loss and the dispersion of pollutants. The most common erosion form, gully erosion, act as preferential ways for the removal and dispersal of runoff and sediments.Although the near-future climate scenarios are uncertain, new and more effective integrated management systems need to adopted to preserve both the food generation potential, and the environment.The purpose of this work is to analyze some techniques for the assessment of the gully erosion, from the photo-interpretation of the sequence of historical photograms, including Machine Learning methods to avoid the subjectivity of the observer, to the acquisition of new multi-spectral images with UAV. The nest step is the selection of the optimal location of the prevention, such as cover crops and vegetative barriers, and control, like check-dams for the interception of runoff and sediments.The final outcome of the proposed techniques is the use of the fill-and spill concept to enhance an intermittent connectivity in the gully networks with the additional advantage of the increased biodiversity in the landscapes.
Identifying financial actors exposed to tipping point risks
Authors: Rocha Juan , Galaz Victor
Published: March 2024

Ecosystems around the world are showing symptoms of resilience loss. With them there is an increasing risk of critical transitions or regime shifts: large, abrupt and difficult to reverse changes in the function and structure of ecosystems. When regime shifts occur they often impact the flow of benefits that people get from nature, and with them the ability of companies, cities or nations to satisfy human needs. Here we ask who is exposed to ecological regime shift risks, and by being exposed, who has the agency or power to intervene and perhaps avoid tipping points?To answer this question we match companies whose activities imply the use or extraction of natural resources in places vulnerable to regime shifts. First, we use Earth observations to quantify resilience loss in marine systems. We also used temeprature records to quantify the probability of extreme and severe heat wave events in the oceans. Both are conditions that can reduce primary productivity and impact fisheries. Then, we identify vessels that fish in these areas of the world and match their owners and shareholders when available in public databases.For publicly listed companies we reconstruct social networks of companies ownership and investments. The networks serve to identify financial actors exposed to ecological tipping points through several investments or regions of the world. The multilayer network can be centred around companies, shareholders, investors, or countries. Clustering at different levels of aggregation allow us to identify actors with disproportional risk exposure, but also companies, investors or countries who could make a difference in mitigating risk.
Coupling Solid Earth and ice temperature models to estimate geothermal heat flow
Authors: Freienstein Judith , Szwillus Wolfgang , Leduc-Leballeur Marion , Macelloni Giovanni , Ebbing Joerg
Published: March 2024

Geothermal heat flow (GHF) is a key element of Solid Earth-cryosphere interactions. However, polar regions as Antarctica are only sparsely covered with heat flow determinations from boreholes, so one must rely on interpolation or regression models of GHF (e.g. machine learning) from other sources to derive a regional map. Interpolation/regression of GHF in this manner depends strongly on the available sparse boreholes, which can distort the resulting regional map.Additional information can be gained from the SMOS (Soil Moisture and Ocean Salinity) satellite by inferring ice temperature profiles with a Bayesian inversion from remote sensing microwave radiometer data. This retrieval uses geothermal heat flow as a free parameter so that it provides a posterior distribution of the GHF needed to explain the ice temperature profiles.We aim to reconcile geophysical geothermal heat flow models with the ice temperature profiles and improve the estimates of GHF with this coupling.We use stationary thermal modelling where we force the ice temperature and lithospheric temperature model to converge at the base of the ice. Using stochastic inversion, we estimate the thermal parameters in the lithosphere. The posterior distribution of the retrieval as constraint for the GHF is included as prior distribution to the inversion to the stationary thermal modelling so that the GHF with the highest likelihood can be estimated.With our approach, we can evaluate a GHF distribution that both explains the ice temperature and lithospheric temperature models and covers large parts of Antarctica.
Estimating open channel surface flow velocities under low luminosity conditions, using fluorescent quinine-based tracing techniques and UAS imagery
Authors: Zehsaz Soheil , L. M. P. de Lima João , M. G. P. Isidoro Jorge , P. de Lima M. Isabel , Martins Ricardo
Published: March 2024

This study discusses the application of innovative fluorescent quinine-based tracer techniques to estimate surface flow velocities under low luminosity conditions. Quinine is known for its luminescent properties when exposed to ultraviolet A (UVA) light. This research involves fieldwork measurements conducted in open channels with varying hydraulic characteristics. The application of quinine solutions in liquid and solid (ice cubes) states into the water flow allows the recording of the movement of the tracers. This movement is registered by tracking the leading edge of the liquid tracer plume or solid particles over specific time intervals. An Unmanned Aerial System (UAS) equipped with a camera was used to record the movement of the tracers in the channels. To benchmark the performance of the quinine-based tracers, flowmeter-based velocity maps and a thermal tracer technique were employed in the experiments. Results indicated that both liquid and solid quinine solution tracers successfully estimated open channel surface flow velocities under low luminosity conditions. The quinine solid tracer can be used as a dual (fluorescent-thermal) tracer and, despite its smaller volume used in the experiments compared to the liquid tracer, the solid form was easier to track. This was attributed to the conservation of a higher quinine concentration for longer periods of time in the solid tracers, resulting in a higher contrast easier to identify. On the other hand, the liquid tracer faded earlier due to diffusion in the turbulent flow. Nonetheless, the main advantage of using the liquid over the solid tracer was its easier availability for the experiments. This study highlights the applicability and reliability of quinine-based tracers in estimating surface flow velocities, in low luminosity conditions. The use of the UAS in the measurements’ set-up facilitated and enhanced data collection, contributing to the accuracy of the results. The observational approach allowed for capturing the inherent luminescent properties of quinine when exposed to UVA light using minimal tracer quantities.
Fragility assessment of levee based on time-dependent reliability analysis under rapid drawdown
Authors: Cho Sung Eun
Published: March 2024

Recent climate change has led to extreme floods surpassing levee design criteria, posing a threat to safety. Consequently, there is a demand for the development of technologies capable of handling such severe floods. In this study, a method assessing failure probabilities, represented by fragility curves, was developed for the levee slope under rapid drawdown. The time-dependent probabilistic stability assessment of the levee slope due to a water level drop was explored. Integrating seepage analysis results from finite element analysis with slope stability analysis, Monte Carlo simulations were conducted to scrutinize the time-dependent behavior of the levee slope under rapid drawdown conditions. The probability of failure was calculated to develop fragility curves for the levee slope. The developed fragility curves were significantly influenced by the drawdown rate. Since the drawdown rate is determined through hydraulic analysis based on flood scenarios, the stability of the water-side slope of the embankment due to a water level drop will be greatly affected by climate change. The fragility curves obtained using the proposed methods are valuable for risk assessment, offering information to evaluate the performance of the levee under various water level drawdown conditions.
Orbital-scale climate and environmental responses of the Western Sahel to shifts in Cenozoic boundary conditions
Authors: Lupien Rachel , Uno Kevin , de Menocal Peter
Published: March 2024

Nearly 100 million people live in and depend on the Sahel for agriculture and natural resources. The region is sensitive to natural climate and environment variations caused by the seasonal movement of the tropical rainbelt. In the paleoclimate record, insolation plays a clear role on West African Monsoon strength, but responses to other forcings like temperature, greenhouse gases, ice volume, and land surface cover are unclear due to the lack of highly resolved, terrestrial records that span major global and regional shifts through time. Here we present leaf wax precipitation and vegetation records from five targeted study windows throughout the last 25 million years, derived from long-chain n-alkane hydrogen (δDwax) and carbon (δ13Cwax) isotopes, respectively, in a sediment core from ODP Site 959 in the Gulf of Guinea, where westerly winds and major river systems transport Western Sahel-sourced material. Analyses of trend and variability document a range of rainfall and vegetation responses to orbital forcings in different boundary conditions in the Oligocene, Miocene, Pliocene, and Pleistocene. We find that both the climate and environment was more variable in times of higher CO2 and global temperatures, suggesting an increase in ecosystem instability moving forward into the future. Because of the high resolution and temporal coverage of these new biomarker isotope records, we can examine relationships between precipitation and vegetation fluctuations, even prior to C4-expansion when there was a strong correlation despite minimal variation in δ13Cwax in a C3 world. Further, we find a drying trend throughout the record, demonstrating that vegetation on long timescales was decoupled from hydroclimate and was like driven by global CO2, advancing our understanding of climate and ecosystem relationships across the Cenozoic.
Spatiotemporal variation in hyporheic nutrient concentrations and interstitial water quality in relation to land use and sediment dynamics
Authors: Hoess Rebecca , Geist Juergen
Published: March 2024

The hyporheic zone at the surface water-groundwater interface is an important compartment of stream ecosystems. It is a hotspot of aquatic biodiversity and key to functional processes, especially in relation to nutrient cycling and retention as well as the self-cleaning ability of streams. The core objective of this study was to understand the complex and heterogeneous role of hyporheic exchange on nutrient cycling and transport over different spatial and temporal scales in relation to anthropogenic land use and sediment dynamics. We assessed sediment dynamics, redox potentials and interstitial habitat quality in conjunction with ion-and nutrient concentrations in the open water and the interstitial zone across a range of silicate stream systems of varying intensities of catchment use and under different discharge conditions. Snow melt events were highly important for the mobilization of fine sediments and stream bed cleaning. In contrast, strong rain events caused high additional fine sediment deposition rates. Fine sediment inputs from small catchment elements like fish ponds strongly depended on pond management. Spatial patterns in hyporheic nutrient concentrations differed from surface water nutrient concentrations, and hyporheic exchange flow varied for different compounds. Intensively and extensively used streams varied strongly in surface water nutrient concentrations while differences in interstitial ion concentrations were much lower. Waterborne denitrification was mostly found in intensively used catchments with elevated fine sediment deposition rates and in fish ponds. Increased fine sediment deposition on the stream bed resulting from excessive erosion input and resulting colmation were regularly observed in intensively used catchments. They can impair the exchange of surface water with the interstitial zone, in turn affecting hyporheic processes. Such knowledge on the potential impact of hyporheic processes on surface water nutrient dynamics along land use gradients is needed to guide future management of catchments and waterbodies to reduce anthropogenic pressures on aquatic ecosystems.
Assessing the deforestation embodied in the European Union consumption and trade of forest risk commodities. 
Authors: Migliavacca Mirco , Bras Teresa , Rougieux Paul , Patani Selene , Bausano Giovanni , Achard Frederic , Avitabile Valerio , Beuchle Rene , Bourgoin Clement , Cescatti Alessandro , Ceccherini Guido , Colditz Rene , De Laurentiis Valeria , Orza Vasco , Vancutsem Christelle , Mubareka Sarah
Published: March 2024

Deforestation and forest degradation, particularly in the tropics, are recognised as important drivers of global warming and biodiversity loss. Forest loss can be driven by several factors, including the expansion of agriculture and pastureland to produce commodities and agroforestry. 

On 29 June 2023, the European Union (EU) Regulation on deforestation-free products came into force, promoting the consumption of 'deforestation-free' products with the aim of reducing the EU's impact on global deforestation and forest degradation, as well as greenhouse gas emissions and biodiversity loss. 

The Regulation states that products related to cattle, timber, cocoa, soy, palm oil, coffee and rubber must be produced on land that is free from deforestation, after 31 December 2020.  

In this contribution, we combine the use of statistics on agricultural and wood production, trade flow data, earth observation on land use change and deforestation, with physically based land footprint and a land use balance models to calculate the impacts embodied in EU bilateral trade and consumption of the selected forest risk commodities. Specifically, we evaluated the impact in terms of land area of forest biomass stocks displaced for the production and consumption of the commodities listed in the Deforestation Free Product Regulation.  

Our evaluation reveals that, in relative terms, the EU significantly contributes to the impacts linked to the production of cocoa and coffee. Soy, cattle, and palm oil emerge as the overall major contributors to deforestation embodied in the EU consumption and are globally responsible for most forest biomass loss. 
Health impacts of long-range transported air pollution in South America: compound events, cascading hazards and the Pantanal 2020 fire crisis.
Authors: Monteiro dos Santos Djacinto , M. de Oliveira Aline , S. F. Duarte Ediclê , A. Rodrigues Julia , S. Menezes Lucas , Albuquerque Ronaldo , de O. Roque Fabio , F. Peres Leonardo , J. Hoelzemann Judith , Libonati Renata
Published: March 2024

Human-induced climate changes have increased the frequency of simultaneous hot–dry events. In 2020, the occurrence of compound droughts and heat waves (CDHW) conditions in the Pantanal (the largest continuous tropical wetland located in central-western Brazil) exacerbated fire risk, leading to unusual amounts of burned area (BA). Despite the well-documented local impacts on the ecosystem and economy, besides regional effects that included black sky episodes in South and Southeastern Brazil, the number of studies investigating the long-range impacts associated with Pantanal fires is still limited, compared to Amazon and Cerrado biomes. Here, we analyzed the long-range transport of smoke from the Pantanal during the 2020 mega fires to the São Paulo state (SPS) and the cascading impacts on air quality and human health statewide, integrating observational, satellite-based, and reanalysis data and atmospheric dispersion models. Three main episodes of transport of smoke-related to peaks of fire events in the Pantanal were identified through air mass trajectories simulated with HYSPLIT, leading to a substantial enhancement in PM2.5 levels over SPS, surpassing World Health Organization guidelines by over 70%-600% in different regions of the state. The EURAD-modeled PM2.5 concentrations during the fire episode aligned with those observed from air quality monitoring stations. Model results highlighted the key role of the South American Low-Level Jet (SALLJ) in the redistribution of smoke plumes in South America, as previously observed in central Brazil and the Amazon basin. Two smoke-induced air pollution episodes coincided with heat waves observed in the SPS, contributing to worsening air quality and amplifying health risks. Thus, the period between October 1st and October 14th was marked by excess mortality of 2,150 (2,095 - 2,206) over 14 days, representing a 21% (17-24%) mortality increase. The impact on mortality was higher in the northwestern SPS, regions more affected by the transported smoke. Our findings reinforce the need to implement public policies associated with fire control and management in the Pantanal, considering the country's large-scale interactions among different regions and biomes, besides adaptation strategies to concurrent and cascading extreme events expected to increase under any future global warming scenarios.
Numerical modelling of the Wilson Cycle: effects of orogenic inheritance on the formation of rifted continental margins
Authors: Li Kai , Brune Sascha , Erdős Zoltán , Glerum Anne
Published: March 2024

The Wilson Cycle describes the repeated opening and closure of oceanic basins from continental rifting to continent-continent collision. The correlation between ancient orogenic belts and young rift systems highlights the significance of orogenic inheritance in shaping the complexities of rifted margins. Orogenic belts can be classified as either pure shear double-vergent or simple shear single-vergent orogens based on their rheological properties and lithospheric deformation mechanisms during lithospheric shortening. Therefore, their resulting pre-rift conditions differ significantly by providing varying inherited structure. The actual inversion from orogen to rift remains poorly understood. For instance, how does inheritance from orogenic processes affect the evolution and final architecture of rifted margins? To investigate this, a numerical forward model was applied that integrates geodynamic thermo-mechanical and landscape evolution software. The simulations include continental collision, post-orogenic collapse and continental rifting, and breakup, through velocity boundary conditions that vary from compression to extension over time. The two end-member orogens are generated by the adjustment of crustal rheology and erosion efficiency. For comparative analysis, we also simulate the extension of laterally homogeneous lithosphere without orogenic inheritance.Results show that collision in cold and strong continental crust generally produces single-vergent orogens. The double-vergent orogen is formed in weak and hot continental crust with low erosional efficiency. However, a transition in the orogenic dynamics occurs under high erosional efficiency, leading to the development of single-vergent orogens for weak and hot crust. The double-vergent orogen features a wide zone of shortening (~350 km) with a large number of conjugate thrust faults. These faults all tend to reactivate as normal-faults during the subsequent phase of rifting and breakup generally occurs around an inherited, overthickened crustal root. These orogens produce largely symmetric rifts. In contrast, the single-vergent orogen is asymmetric with most shortening accommodated along one dominant interface during the orogenic stage. During rifting, this subduction interface is fully reactivated, accommodating most of the extension and determining the crustal breakup location. These orogens produce an asymmetric rift. In conclusion, orogenic inheritance controls the localization of deformation along pre-existing structural weaknesses and reactivation mechanisms, resulting in complex rifted margins.
Development of a full waveform inversion method for acoustic waves in the presence of wind: application to synthetic and realistic cases 
Authors: Gerier Solene , Martin Roland , Garcia Raphael
Published: March 2024

Inferring a model of the wind, pressure, velocity in the atmosphere is an inverse problem, for which the state of the art methods use the travel times of acoustic waves.We aim to solve such an inverse problem by adding more information and using a full waveform (in this case pressure variation) as infrasound observation.In particular, we place our study in the context of an inversion of infrasound due to an explosion (or quake) in a domain, without gravity, without attenuation but with the wind as a non isotropic parameter. The addition of wind is important because wind can have an significant impact on the waveform (like the wave guide). To this end, we adapted the adjoint method developed in seismology to a fluid in movement : sensitivity kernels have been computed in the case of acoustics waves in the presence of wind (linearised Navier-Stokes equations).The sensitivity kernels play the role of a gradient in an optimization framework that recovers the variation of atmospheric parameters (density, wind, pressure, speed).Sensitivity kernels have been studied on simple and more realistic cases in 1d and 2d.We validated the sensitivity kernels acquired by the adjoint method by comparing them with those obtained by auto-differentiation. Discontinuities near the source and receivers are observed in the sensitivity kernels. We studied the influence of source frequency on the kernels and on these discontinuities.These encouraging results on sensitivity kernels led us to test initial synthetic inversion in 1d and 2d.We proposed an analysis of the efficiency of the inversion depending on the choice of parametrization, conjugate gradient method and regularization term.
FIELD VNIR-SWIR SPECTRORADIOMETRY FOR CLASSIFICATION OF MATERIALS IN THE VALDEFOREZ DEPOSIT (SPAIN) ACCORDING TO THE Li CONTENTS.
Authors: García Romero Emilia , Barrios Santos , Valls David , Suárez Mercedes
Published: March 2024

The Li mineralization of Valdeflórez (Cáceres province, Spain) is related to an extensive metasomatism of Ordovician metasedimentary rocks due to the circulation of B- and Li-rich magmatic hydrothermal fluids associated probably with a granite dome (Torres-Ruiz, et al., 1996). Li-rich micas mainly, and other Li-rich minerals like amblygonite-montebrasite, appear as consequence of this hydrothermal alteration. The aim of this study is to evaluate the use of the VNIR-SWIR spectroradiometry to the materials classification according to the Li content during the exploitation mining works and to the mining prospection in similar areas. The results of a study conducted by VNIR-SWIR portable spectroradiometry on 335 samples coming from representative cores of the mineralized area are shown. Complementary, a mineralogical study by XRD and chemical analysis by ICP were performed. Visible and infrared wavelength ranges were studied separately, and a classification of the high-resolution spectra was done to compare with the chemical and mineralogical composition of the samples. The spectra were classified into six groups according to their morphology in the near and short-wave IR range, and these groups correspond to a different mineralogy of major components, as logical.  However, there is not a clear relation among these groups and the Li-content because Li is mainly in micas as octahedral substitutions, which influence on the spectral features is neglectable. A higher content in micas does not imply a higher content in Li. Consequently, a spectral signature of Li could not be determined, because Li is not directly related to the content of a certain mineral, micas in this case. As a conventional spectral signature is not useful in this case, because it classified mineralogy but not Li-content, a detailed study of the hight resolution spectra obtaining different parameters (both from the spectra and from the second derivatives of the spectra) was performed. The joint statistical treatment of the hyperspectral, mineralogical, and chemical data allowed us to find a plot of the materials classification according to the Li content from the spectral data which means a very fast procedure for classification that could be automatized though IA.Acknowledgement: TED2021-130440B-I00 funded by MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTRTorres-Ruiz, J., Pesquera, P., Gil, P., Casas, J. 1996. Tourmalinites and Sn-Li mineralization in the Valdeflores area (Cáceres, Spain). Mineralogy and Petrology 56:209-223.