bluuebunny/crossref_metadata_2025 huggingface dataset:
Global runoff partitioning based on Budyko and machine learning
Authors: Cheng Shujie , Hulsman Petra , Koppa Akash , Cheng Lei , Beck Hylke E. , Miralles Diego G.
Published: February 2023

Partitioning runoff accurately into baseflow and quickflow is crucial for our understanding of the water cycle and for the management of droughts and floods. However, global datasets of long-term mean runoff partitioning are rare, even more so datasets relying on physically-based methods. Here, we present a new global 0.25° dataset of runoff, baseflow and quickflow using a hybrid approach of Budyko-based methods and machine learning (ML). The parameters in the Budyko curve and Budyko-based baseflow curve (BFC curve) are estimated with ML (boosted regression trees, BRT) as a function of catchment characteristics. The BRT models are trained and tested in 1226 catchments worldwide, and then applied globally at grid scale. The catchment-trained models show good performance during the testing phase with R2 equal to 0.96 and 0.87 for runoff and baseflow, respectively. The dataset developed in this study shows that 30.3±26.5% (mean ± standard deviation) of the precipitation is partitioned into runoff of which 20.6±22.1% is baseflow and 9.7±10.3% is quickflow. The global long-term mean baseflow in this study (151±181 mm yr–1) is lower than that from the Global Streamflow Characteristics Dataset (GSCD, 241±321 mm yr–1) and higher than that from ERA5-Land (79±145 mm yr–1). This study provides a unique, physically and observationally constrained global dataset of the long-term runoff partitioning. The large differences among different datasets suggest that global runoff partitioning is highly uncertain and requires further investigation.
River ecosystems: A tale of superlatives and hidden beauty
Authors: Battin Tom J.
Published: February 2023

River ecosystems are superlatives in many respects. Their networks represent the largest biogeochemical nexus between the continents, oceans and atmosphere. River networks span multiple catchments, even biomes, and are highly dynamic in space and time. The world’s rivers contribute relatively little by areal extent, but their CO2 emissions are of the same magnitude as the CO2 sequestration flux by the world’s oceans. Rivers figure among the most heterotrophic ecosystems on Earth, metabolizing terrestrial organic carbon. Owing to their dendritic structure, the biodiversity that river networks host is exceptionally high. Finally, needless to emphasize how critical the ecosystem services are that rivers provide. Central to many of these river superlatives are microbial biofilms that abundantly coat the sedimentary surfaces of the river beds. A microbiome, encompassing all three domains of life, shapes, in conjunction with the turbulent nature of water flow, intriguing biofilm architectures. Biofilms, a hidden beauty emanating from the interactions between biology, physics and chemistry, regulate ecosystem energetics and are therefore an important linchpin between river biodiversity and biogeochemistry.In my lecture, I will attempt to provide the state-of-the-art of global river carbon biogeochemistry and biofilm ecology. An emphasis will be given on the rivers that literally drain the roof of our planet, now at risk because of climate change. It is my hope, that soon we will appreciate the world’s river networks as we do appreciate the oceans and various terrestrial ecosystems.
Understanding collective behavior of bedrock and porous aquifers and their contribution to the total water storage and discharge dynamics of a high mountainous catchment – Dolomites, Alps
Authors: Chen Zhao , Lucianetti Giorgia , Hartmann Andreas
Published: February 2023

High mountains, which exhibit alpine and subalpine characteristics, represent 15% of the earth’s land area and are estimated to contribute about 17% of global runoff. Depending on hydrogeological setting, a significant amount of catchment water can be stored in high mountainous underground as groundwater, which can contribute substantially to streamflow and represent an important water source. However, high-alpine catchments are often characterized by great geological complexity and highly heterogeneous hydraulic properties. For that reason, proper system characterization, monitoring and modeling remain challenging. In this study, we investigated a geologically complex alpine catchment in the Dolomites (Italian Alps) by combining hydrogeological investigation, hydrological monitoring and numerical modelling. A process based but spatially lumped hydrological model was applied to simulate the continuous measured catchment discharge in a period of three years, which covers a large variation of hydrodynamic conditions. The current model structure couples the sequential hydrogeological units within the studied catchment: (1) the fractured dolomitic rocks as bedrock aquifer and 2) the unconsolidated deposits accumulating on the slopes and at the valley floor as porous aquifer. In order to evaluate the model structure and parameterization in depth, we applied a multi-step evaluation approach considering both parameter sensitivity and uncertainty. The current modelling results demonstrate that the newly developed model can reproduce most discharge behavior of aquifers. The model indicates a dynamic linkage between surface and subsurface storage units during different flow conditions. Besides the matrix and conduit flow in fractured dolomitic aquifer, it highlights the important role of unconsolidated sediments (porous aquifer) to the storage and discharge behavior of the entire groundwater system. Furthermore, with the comprehensive model evaluation we learned the model structure deficit during extreme high flow condition and proposed a more detailed hydrogeological conceptual model to improve the model realism.
Observed and projected changes in the diurnal temperature range at European cities with different base climate
Authors: Katavoutas George , Founda Dimitra , Varotsos Konstantinos V. , Giannakopoulos Christos
Published: February 2023

Many regions across the globe have been witnessing changes in both mean climate and climatic extremes during the last decades. Cities in particular, where the concentration of urban population is high, have been in the spotlight of scientific research seeking to address climate-related issues. At the same time, climate change is expected to largely impacts cities until the end of 21st century. However, changes in air temperature levels, as an essential element of the climate, are probably not uniform nor of the same rate across different areas of the globe. An important indicator of the global climate change is the diurnal temperature range (DTR), defined as the difference between the daily maximum and daily minimum air temperature, thus reflecting the temperature variation within a day.
This study analyses the distribution and long-term trends in DTR in seventeen European cities of different base climate. The response of DTR under exceptionally hot weather has also been investigated. The study uses observed and projected data of daily maximum and minimum air temperature over the periods 1961-2019 and 1971-2100, respectively. The projected data, over the studied cities for the closest land grid point to the stations’ location, were derived from the Regional Climate Model (RCM) RCA4 of the Swedish Meteorological and Hydrological Institute driven by the Max Planck Institute for Meteorology model MPI-ESM-LR, with the simulations carried out in the framework of the EURO-CORDEX modeling experiment. The projected data were bias adjusted applying the empirical quantile mapping technique. Future simulations were based on two climate scenarios, the Representative Concentration Pathways (RCPs) 4.5 and 8.5.
The distribution of the DTR frequency based on observations shows a similar pattern in cities that share the same background climate, while is clearly differentiated at diverse climate types. The mean DTR for normal summer days (maximum air temperature lower than 95 percentile) ranges between 8.0 and 10.5 oC for all cities, with the exception of Nice that shows lower mean DTR and Nicosia, Madrid and Bucharest that present higher. The change of the mean DTR between summer normal days and hot days (maximum air temperature higher than 95 percentile) is greater for cities in higher latitudes, while it is smaller for cities in lower latitudes. According to the projected data for the period from 1971 to 2100 under the RCP4.5 scenario, a statistically significant decreasing trend in mean DTR/yr is projected for the cities in the highest latitudes (Oslo, Stockholm and Helsinki), suggesting higher increasing rates in the minimum air temperature compared to the maximum air temperature. At the same time, the opposite result is expected in Madrid (statistically significant increasing trend), while no statistically significant trends in mean DTR are projected for the rest of the cities.
Integration of at-scale field observations and application of surrogate modelling strategies for optimal design of ATES systems in the Sherwood Sandstone aquifer
Authors: Christelis Vasileios , González Quirós Andrés , Abesser Corinna , Boon David , Hough Edward , Spence Michael
Published: February 2023

Aquifer Thermal Energy Storage (ATES) systems use reversible abstraction and injection in combination with warm and cold wells to provide efficient heating and cooling solutions at scales up to ~0.5 MW per installation. It has been shown that these systems are able to improve the efficiency of thermal installations, but rely on an appropriate design, especially when several ATES systems share the same aquifer. In this work, we combine groundwater flow and heat transport numerical models with optimization frameworks to investigate the optimal distribution of wells for avoiding system interferences and improving recovery efficiency. To that end, we employ hypothetical modelling scenarios based on geological properties of the Sherwood Sandstone bedrock aquifer as one of the main potential targets for the development of ATES systems in the UK. Some of the available information is acquired from activities at the UK Geoenergy Observatory (UKGEOS) in Cheshire, which is under construction and will be equipped with a range of technologies and monitoring sensors for research, training, and on-site experiments. The Observatory will be open to industry and the research community to evaluate technological options for shallow geothermal use and energy storage and to gain a detailed hydraulic and thermal characterization of the Sherwood Sandstone. As practical application, we present an approach for the optimal design of the installation of multiple doublets that consider various spatial features as decision variables. The benchmark solution is provided by a simulation-optimization framework that uses a direct coupling of the groundwater flow and heat transport numerical model with an evolutionary algorithm. This approach is typically hampered by increased computational cost due to the time-intensive numerical simulations and the thousands of objective function evaluations required until convergence of the evolutionary algorithm is achieved. Therefore, we also investigate a lower computational resource strategy by applying surrogate-assisted optimization methods which are either embedded in the operations of the evolutionary algorithm or utilize an adaptive-recursive framework. The performance of the surrogate-based optimization method is assessed via several independent optimization trials and for different computational budgets. The ability of the surrogate-based optimization frameworks to approximate a near global solution is compared against the benchmark solution.
Intra-Plate Deformation of the Pacific: Evidence from Oceanic Plateaux and Geodynamic Models
Authors: Gün Erkan , Pysklywec Russell , Heron Philip , Topuz Gültekin , Göğüş Oğuz
Published: February 2023

The theory of plate tectonics acknowledges that drifting lithospheric plates are rigid and do not undergo substantial deformation except near or at plate boundaries. However, studies have shown that intra-plate deformation is a feature for continental lithosphere and can originate from different mechanisms such as lithospheric drips, delamination, and in-plane stresses. On the other hand, there is not well-known understanding of tectonic deformation within the interior of ocean plates. We compile data to show there is geological and geophysical evidence documenting that the drifting Pacific plate has been undergoing appreciable extensional deformation at the locations of its oceanic plateaux. Namely, the Ontong Java, Shatsky Rise, Hess Rise, and Manihiki plateaux show extensive evidence for normal faults, horst-graben structures, and extension related magmatic activity at a significant distance from plate boundaries. Furthermore, this deformation occurred after the initial emplacement of their associated large igneous provinces (LIPs) and before their arrival to subduction zones.We present numerical geodynamic experiment results demonstrating that terranes embedded in ocean plates can undergo extensional deformation prior their accretion to the overriding plate due to slab-pull (e.g., a “subduction pulley”).  Our numerical models show that the subduction pulley is also a valid mechanism for the extensional deformation of the Pacific oceanic plateaux even at remote locations from the plate boundaries. For instance, tensional stress originated from down-going slabs can be transmitted through strong oceanic lithosphere over long distances (>1000 km) and deform the plate at its weak oceanic plateaux regions. The numerical experiments further demonstrate that high crustal thickness reduces the bulk strength of ocean lithosphere at the location of oceanic plateaux and makes them susceptible to slab-pull related extension—manifesting on the surface as intra-ocean plate deformation.
Mt. Etna volcano: what have we learned from 20 years of continuous GNSS observations?
Authors: Palano Mimmo , Pezzo Giuseppe , Chiarabba Claudio
Published: February 2023

Mt. Etna volcanic activity has been characterized, in the last two decades, by more than 150 paroxysmal events (from moderate to intense and impulsive explosive activity, coupled sometime to voluminous lava flows) as well as by some large eruptive events (e.g., 2001, 2002-03, 2004-05, 2006, 2008) involving the upper sector of the northern and southern flanks of the volcano, along with the summit craters. Taking advantage of an extensive dataset of continuous GNSS stations covering the entire volcano edifice, we propose an unprecedented and detailed picture of different deformative stages. Raw GNSS observations, are processed by using the GAMIT/GLOBK software and achieved results, e.g. station daily time series and network-scale surface deformation fields, are referred to a local reference frame. By inspecting the daily baseline changes for EDAM and EMGL stations we detected a total of 59 different ground deformation phases consisting in 29 inflation phases, 21 deflation phases, 5 magmatic intrusions and 4 periods with no significant deformation. The surface deformation for each detected phase is used to constrain isotropic half-space elastic inversion models, therefore providing significant constraints on subsurface Mt. Etna’s magmatic storages. We integrate our results with recent tomographic models, correlating the inferred sources with VP and VP/VS anomalies, in order to provide exhaustive interpretative model into the general volcano-tectonic context of Mt. Etna and in turn, new insight on hazard assessment.
Conserved quantities in the Ekman layer
Authors: Llorente Víctor J. , Padilla Enrique M. , Díez-Minguito Manuel
Published: February 2023

The classical Ekman (1905)'s theory of wind-driven currents at the surface boundary layer is a well-known mathematical model that describes transport phenomena in coastal processes, (e.g.) upwellings and downwellings, and represents an essential part of modern oceanography. Understanding the Ekman layer is important to quantify deviations to observed magnitudes from the classical behavior. In this theoretical work, the Ekman layer is revisited through Noether's theorem. This theorem plays a central role in theoretical physics and Lie group theory showing a direct connection between symmetries and conservation laws. Therefore, the goal of the work is to determine what quantities are conserved in the Ekman layer.
Separating tree systems in agricultural lands from forests using Deep learning
Authors: Yang Wanting , Ortiz Gonzalo Daniel , Tong Xiaoye , Pierre Johannes Gominski Dimitri , Brandt Martin , Kariryaa Ankit , Reiner Florian , Fensholt Rasmus
Published: February 2023

Distinguishing trees on agricultural land from forests is essential for a better understanding of the relationship between forests and human farming activities. However, it is difficult to separate them with remote sensing imagery since they share similar canopy cover, especially on the edge of the amazon rain forest, which has a much-complicated agriculture pattern. Except for annual crops and pasture, there are also lots of agroforestry applications and shifting cultivation, which integrates many tree systems. And those tree systems are not well separated from the forest in the existing land cover map. Recent techniques allow for the mapping of single trees outside of forests, now we take the next step by identifying those diverse tree-involved systems in agricultural land. Here we aim to generate a robust, cost-efficient method to distinguish trees within agricultural land from the forest. We started our exploration from Peruvian Amazon, where the competition for land has increased in the last decades, causing possible adverse effects on livelihoods and ecosystem services. Deep learning models, data sampling, and fine-tuning strategies are tested and optimized with PlanetScope satellite imagery. Our research target is to provide a tool for separating tree systems in farmland from the forest. It can also be used as a base map to explore the dynamic of agriculture transition and its impact on livelihoods and ecosystem services. 
Identification of sensitive regions to climate change and anticipation of climate events in Brazil
Authors: Caseri Angelica , A. Rodrigues Francisco
Published: February 2023

In Brazil, the water system is essential for the electrical system and agribusiness. Understanding climate changes and predicting long-term hydrometeorological phenomena is vital for developing and maintaining these sectors in the country. This work aims to use data from the SIN system (National Interconnected System) in Brazil, from the main hydrological basins, as well as historical rainfall data, in complex networks and deep learning algorithms, to identify possible climate changes in Brazil and predict future hydrometeorological phenomena. Through the methodology developed in this work, the predictions generated showed satisfactory results, which allows identifying regions more sensitive to climate change and anticipating climate events. This work is expected to help the energy generation system in Brazil and the agronomy sector, the main sectors that drive the country's economy.
Solar Orbiter: The Sun up close
Authors: Zouganelis Yannis , Müller Daniel , De Groof Anik , Williams David , Walsh Andrew , Janvier Miho , Nieves-Chinchilla Teresa , Lario David , Musset Sophie
Published: February 2023

The ESA/NASA Solar Orbiter mission performed its first close solar encounters at 0.32 au in March 2022 and at 0.29 au in October 2022. By combining high-resolution imaging and spectroscopy of the Sun with detailed in-situ measurements of the surrounding heliosphere, Solar Orbiter enables us to study the Sun's corona in unprecedented detail, and determine the linkage between observed solar wind streams and their source regions on the Sun. Its science return will be enhanced significantly by coordinated observations with other space missions, e.g. Parker Solar Probe, as well as new ground-based telescopes like DKIST. Over the course of the 10-year mission, Solar Orbiter's highly elliptical orbit will get progressively more inclined to the ecliptic plane. Thanks to this new perspective, Solar Orbiter will deliver images and comprehensive data of the unexplored Sun’s polar regions and the Sun's far side. This talk will provide a status update of the mission and the science operations performed during the first two science perihelia, and summarise early science results.
Abiotic mineral formation: the impact of solution stoichiometry on nucleation and growth
Authors: Wolthers Mariette , Karami Alemeh , Seepma Sergej
Published: February 2023

All of the crystals that form in natural waters on Earth are formed through reaction between oppositely charged ions. In these crystals, the ions are present in an ideal, charge-balanced ionic ratio. In contrast, the natural solutions in which they form, contain widely diverging ionic ratios (stoichiometries). Consequently, one type of ion, either the anion or the cation, will be in excess and the other in limitation. Experimental results have shown previously that the solution ionic ratio affects crystal growth rate at constant degree of supersaturation, pH, temperature and ionic strength. This behaviour can be explained with an ion-by-ion growth model (e.g. Wolthers et al., 2012a).In this presentation, I will illustrate how this imbalance impacts the new formation, i.e. nucleation, of CaCO3, BaSO4 and FeS. Solution stoichiometry affects the timing and rate of nucleation, the charge of the particles formed and potentially their aggregation behaviour (e.g. Seepma et al., 2021), among others. The impact of solution ionic ratio on nucleation and growth varies for the three different mineral systems and indicates that natural mineralisation processes will also depend on solution stoichiometry. References:Seepma, S., Ruiz Hernandez, S., Nehrke, G., Soetaert, K., Philipse, A. P., Kuipers, B. W. M., & Wolthers, M. (2021). Controlling CaCO3 particle size with {Ca2+}:{CO32-} ratios in aqueous environments. Crystal Growth & Design, 21(3), 1576-1590. https://doi.org/10.1021/acs.cgd.0c01403Wolthers, M., Nehrke, G., Gustafsson, J. P., & Van Cappellen, P. (2012). Calcite growth kinetics: Modeling the effect of solution stoichiometry. Geochimica et Cosmochimica Acta, 77(4), 121-134. https://doi.org/10.1016/j.gca.2011.11.003
Particle Energisation in a 3D Collapsing Magnetic Trap Model With a Braking Jet
Authors: Mowbray Kate , Neukirch Thomas
Published: February 2023

Investigating the motion of charged particles in time- and space-dependent electromagnetic fields is central to many areas of space and astrophysical plasmas. Here we present results of studying the energy changes of particle orbits that are trapped in inhomogeneous and time-dependent magnetic fields with rapidly shortening field lines. These so-called collapsing magnetic trap (CMT) models can be useful to better understand the particle energisation processes occurring below the reconnection region in a solar flare. Braking jets may be associated with magnetic reconnection, for example when a sunward flow slows down as it approaches a stronger region of magnetic field. We generalise a 2D CMT model with braking jet (Borissov et al., 2016) to three dimensions and investigate the dynamics of particles in this 3D CMT model. The resulting particle orbits show a sensitive dependence of particle energies on the initial conditions of orbits, with initial pitch angles playing a particularly important role. This sensitive dependence relates to the time evolution of trapping regions that develop in the braking jet region of the CMT, ensuring that some orbits spend a significant time in the loop legs of field lines, whilst others escape these regions for the duration of the simulation. These loop leg trapped particle orbits see significantly lower energy gains than those orbits that repeatedly pass the loop top, with some of these particles even losing energy. This gives us greater insight into the importance of the curvature of collapsing loop tops for the Fermi acceleration mechanism acting on the particles. 
 
Borissov A. et al., Solar Physics 291, Issue 5, 1385 
Methanogenic Pathways in Pürgschachen Moor
Authors: Glatzel Stephan , Mari-Liis Bagó
Published: February 2023

Microbially mediated methanogenesis is a considerable source of methane (CH4) and has a major role in the global carbon cycle. In peatlands, acetate, CO2 and methylated compounds are precursors for CH4 and different substrates are used by different microorganisms. CH4 may be produced by a) acetate disproportionation (acetoclastic/acetotrophic methanogenesis), b) reduction of carbon dioxide by dihydrogen (hydrogenotrophic methanogenesis), and c) using methylated compounds (methylotrophic methanogenesis). As different methane sources have different carbon isotopic ratios, those signatures may be used to divide emissions from different sources, although these can vary temporally and spatially. Here, we hypothesize that CH4 production pathways from Sphagnum peat with clipped vascular vegetation (Callluna Vulgaris) significantly differs from CH4 production pathways from peat cores with vascular plant cover.In order to test this hypothesis, six undisturbed peat mesocosms from Pürgschachen Moor were sampled to determine the CO2 and CH4 efflux and its 12C/13C signature for four weeks. Three control cores were left unclipped as control and in three cores, vascular vegetation was clipped to assess the significance of vascular vegetation to CH4 emissions. Ancillary parameters examined were dissolved organic carbon and acetate concentrations in peat pore water as well as hot water soluble carbon from peat.CO2 fluxes ranged in clipped cores between 2.4 to 12.2 g m-2 h-1 and in control cores between 4.13 to 14.6 g m-2 h-1. CH4 fluxes ranged from 0.058 to 0.16 g m2 h-1 in the clipped cores and from 0.046 to 0.751 g m2 h-1 in the control group. For both CO2 and CH4, treatment had a significant effect on the fluxes.  δ13C for CH4 values in the experiment group (-55.6 ± 2.45‰) were in the same range as the control group, whereas after the clipping the experiment group values slightly decreased to -54.1 ± 2.65‰. For the control group, δ13C values were -55 ± 2.2‰. δ13CO2 was -11.2 ± 0.72‰ before and -10.8 ± 0.67‰ after clipping in the experiment group. In the control group, the average was -11.2 ± 0.71‰.Taking into consideration the aforementioned results and other parameters measured throughout this study, it can be acclaimed that the presence of vascular vegetation changes the ability of the peat profile to produce and emit both CO2 and CH4. Even though no significant difference found between the control and the experiment group for δ13CH4, it can be acclaimed that in Pürgschachen Moor the hydrogenotrophic pathway is dominant, with average δ13CH4 values of -55 ± 2 ‰, although both pathways coexist.
Towards probabilistic impact-based drought risk analysis – a case study on the Volta Basin
Authors: Wens Marthe , Hamed Raed , de Moel Hans , Massabo Marco , Mapelli Anna
Published: February 2023

Understanding the relationships between different drought drivers and observed drought impact can provide important information for early warning systems and drought management planning. Moreover, this relationship can help inform the definition and delineation of drought events. However, currently, drought hazards are often characterized based on their frequency of occurring, rather than based on the impacts they cause. A more data-driven depiction of “impactful drought events”- whereby droughts are defined by the hydrometeorological conditions that, in the past, have led to observable impacts-, has the potential to be more meaningful for drought risk assessments.In our research, we apply a data-mining method based on association rules, namely fast and frugal decision trees, to link different drought hazard indices to agricultural impacts. This machine learning technique is able to select the most relevant drought hazard drivers (among both hydrological and meteorological indices) and their thresholds associated with “impactful drought events”. The technique can be used to assess the likelihood of occurrence of several impact severities, hence it supports the creation of a loss exceedance curve and estimates of average annual loss. An additional advantage is that such data-driven relations in essence reflect varying local drought vulnerabilities which are difficult to quantify in data-scarce regions.This contribution exemplifies the use of fast and frugal decision trees to estimate (agricultural) drought risk in the Volta basin and its riparian countries. We find that some agriculture-dependent regions in Ghana, Togo and Côte d’Ivoire face annual average drought-induced maize production losses up to 3M USD, while per hectare, losses can mount to on average 50 USD/ha per year in Burkina Faso. In general, there is a clear north-south gradient in the drought risk, which we find augmented under projected climate conditions. Climate change is estimated to worsen the drought impacts in the Volta Basin, with 11 regions facing increases in annual average losses of more than 50%.We show that the proposed multi-variate, impact-based, non-parametric, machine learning approach can improve the evaluation of droughts, as this approach directly leverages observed drought impact information to demarcate impactful drought events. We evidence that the proposed technique can support quantitative drought risk assessments which can be used for geographic comparison of disaster losses at a sub-national scale.
Volcano-tectonic deformation of the submarine flank of Cumbre Vieja volcano, La Palma, Canary Islands
Authors: Geersen Jacob , Gross Felix , Krastel Sebastian , Böttner Christoph , Sánchez-Guillamón Olga , Vázquez Juan-Tomás , Leon Ricardo , Rollwage Luisa , Sudhaus Henriette , Sippl Christian , Urlaub Morelia
Published: February 2023

The land and seascape of the Canary Islands witnesses a long history of volcanic growth and volcano-tectonic deformation. This interplay has generated a spectacular morphology that stretches over almost 8 km (vertically) from the foot of the western volcanic islands at 4.000 m water depth to the top of the Pico del Teide at 3.718 m above sea level. On 19th September 2021, Cumbre Vieja volcano on the island of La Palma, experienced its longest eruption in historic times, lasting for three months. The eruption was accompanied by widespread deformation, expressed among others by tens of thousands of earthquakes, meter-scale vertical elevation changes, fractures and eruptive fissures that opened along the onshore flank, and the build-up and collapse of volcanic cones. It is now a major task for researchers to identify and untangle the different deformation patterns in order to learn about volcano-tectonic and related sedimentary processes before, during, and after the eruption. Because the largest volume of the volcano locates underwater, a comprehensive analysis of volcano-tectonic deformation requires marine data. Here we present a synthesis of legacy hydroacoustic data from the last century together with new data collected in recent years and especially after the 2021 eruption. The new data include multibeam bathymetry from VULCANA_1015, VULCANA_0318 and VULCANA_III_LP_0921/1021-0222 cruises which were supported by the Spanish Institute of Oceanography (IEO-CSIC) funds through the VULCANA project. These data cover the submerged flank down to a water depths of 1940 m with a 10x10 m grid spacing. We further collected multibeam and sediment echosounder data from the lower part of the island slope and adjacent abyssal seafloor between the islands of La Palma and El Hierro during RV MARIA S. MERIAN Cruise 113 in January 2023. Together the different data cover the western side of La Palma, which has collapsed repeatedly in a likely catastrophic manner over geologic times, with the Cumbre Nueva debris avalanche at 125–536 ka representing the youngest event. We use the data to map sedimentary and tectonic structures including fault outcrops, submarine canyons and channels, mass-transport deposits, landslide scars and blocks as well as folded and faulted strata between the coast and about 4500 m water depth. The results add to a land-to-sea analysis of volcano-tectonic deformation at Cumbre Vieja volcano including the spatial extent and outline of the mobile western flank, which seems to be moving into the Atlantic Ocean.
Multiscale water accounting under climate change in a transboundary West African basin
Authors: Dembélé Moctar , Salvadore Elga , Zwart Sander , Ceperley Natalie , Mariéthoz Grégoire , Schaefli Bettina
Published: February 2023

Water accounting frameworks assess water availability and consumption of various users and are key tools to inform decision and policy making for integrated water resources management. This study presents a modelling framework that integrates a spatially explicit hydrological model and climate change scenarios with the Water Accounting Plus (WA+) tool to anticipate future water resource challenges and provide mitigation measures. The fully distributed mesoscale Hydrologic Model (mHM), spatially calibrated with multiple satellite remote sensing products, is used to predict water fluxes, stocks and flows in the transboundary Volta River basin (VRB) in West Africa. The mHM model is forced with a large ensemble of climate change projection data from eleven general circulation models (GCMs) downscaled by four regional climate models (RCMs) under the representative concentration pathway RCP8.5, obtained from CORDEX-Africa. Outputs from mHM are used as inputs to the WA+ framework to report on the state and trends of water resources over the historical baseline period 1991-2020 and the near-term future 2021-2050. The basin-scale WA+ reporting is reinforced with a multi-scale summary of water accounts across spatial domains including four climatic zones, four sub-basins and the six riparian countries.The long-term multi-model ensemble mean of the net inflow to the basin is found to be 419 km3/year with an inter-annual variability of 11%, and is projected to slightly increase in the near-term future (2021-2050), due to the increase in rainfall, thereby highlighting the need for adaptation strategies to optimize the water-energy-food-ecosystem nexus in the VRB.
Ecological change in the early Anthropocene: Insight from death assemblages of the locally extinct European flat oyster (Ostrea edulis) in the Sylt-Rømø Bight
Authors: Sander Lasse , Pogoda Bernadette , Reise Karsten , Waser Andreas
Published: February 2023

The European flat oyster (Ostrea edulis) provided relevant ecosystem functions and services as a keystone filter feeder and habitat forming species across the North Sea. At the turn of the last century, the species suffered a severe decline following a brief period of massive economic exploitation. Today, a few local populations still exist in e.g. the UK, the Netherlands, and Denmark. In the German North Sea, O. edulis is classified as functionally extinct.The Sylt-Rømø Bight is one of the largest tidal back-barrier environments of the European Wadden Sea and is located on the border between Germany and Denmark. The environment underwent significant changes over the last millennia driven by natural landscape dynamics and, more recently, by anthropogenic claims to land and coastal resources. Despite its demise as a living organism, O. edulis shells are still widely found in the area and remain a part of the sedimentary environment that potentially bears evidence of past ecological and geomorphological change. Written and graphic accounts on the past state, composition and distribution of Ostrea reefs are rare and unreliable.In this case study, we explore shell assemblage counts, geospatial data, and radiocarbon dating as tools to better understand ecological change over the past few centuries. More than a hundred dredge profiles were collected in the German part of the Sylt-Rømø Bight during two campaigns in summer 2021 and 2022. The results show marked spatial differences in the shell material regarding total dredged volume, overall species composition, size distribution, and taphonomic state. These differences can partly be explained by landscape dynamics and the economic history of the area (blue mussel cultivation). Radiocarbon dating of Ostrea shells (n=42) from three locations suggests that Ostrea banks at more exposed sites were short-lived and dynamic features, while ages from a less exposed site suggest the continuous presence of Ostrea over (at least) three thousand years.This example showcases that methods from geoarchaeological and geoscientific contexts can help to shed light on the more recent paleoecology of coastal environments over historical timescales, where sufficient depth of information is lacking from other sources. Beyond pure curiosity, the information has a clear value as benchmark to define aims for marine conservation and restoration efforts.
Insights for late-Variscan kinematics and oroclinal bending in the Central Iberian Zone from the paleomagnetic characterization of the Cambrian Urda-Los Navalucillos Limestone (Montes de Toledo, Spain).
Authors: Durán Oreja Manuela , Calvín Pablo , Villalaín Juan José , Ayarza Puy , Martínez Catalán José R.
Published: February 2023

As a result of the collision of Gondwana, peri-Gondwanan terranes, and Laurussia in the Upper Devonian to early Permian, various Paleozoic oceans are thought to have closed, leading to the formation of the Variscan belt. The belt experienced oroclinal bending in the latter phases of the orogeny, a process that became significant in the Iberian Massif, the westernmost part of the European Variscan belt. There, the belt acquired an S-shaped attitude defined by the Central Iberian Arc (CIA) to the south and the Ibero-Armorican Arc (IAA) to the north. The early Variscan structures, the magnetic anomalies, and the tectonostratigraphic zonation of the Iberian Massif are all bent by both arcs.The IAA is extensively studied, but the tectonic evolution of the CIA is not well resolved because a large part of it is covered by sediments of the Paleogene Duero basin. Paleomagnetism is a very useful tool used to identify possible vertical axis rotations. Therefore, we carefully searched for outcrops that may record paleomagnetic directions that could shed some light on the development of the CIA.Weakly metamorphic Cambrian limestones from the southern limb of the CIA were subjected to magnetic and paleomagnetic investigations. 32 sites in 5 outcropping structures in the Urda-Los Navalucillos Formation of Montes de Toledo (Central Iberian Zone, Spain), close to the CIA hinge zone, yielded more than 270 cores. These outcrops were affected by two regional-scale Variscan folding phases, namely C1 and C3, which developed interference patterns. A characteristic paleomagnetic component was found at 19 sites in 4 of the structures. This component reveals different temporal correlations with C3 folds, from syn-folding to certainly post-folding. The resulting mean directions of the magnetic vector, in geographic coordinates, consistently display northward to north-western declinations and negative, low inclinations, indicating that they have been acquired before the geomagnetic reverse polarity Kiaman superchron when Iberia was in the southern hemisphere. Although the inclination of the paleomagnetic mean directions is consistent amongst structures, the declination varies from N to NW, suggesting a vertical axis rotation synkinematic to C3 folding previous to 318 Ma. These directions indicate that the early evolution of the southern limb of the CIA was differentially recorded by the paleomagnetic directions of the different structures and underwent a 42º clockwise rotation during the late Carboniferous. The later development of the IAA was associated with a significant counterclockwise rotation that affected the entire paleomagnetic record. (Research support: SA084P20, PID2020-117332GB-C21, PID2019-108753GB-C21, AEI/10.13039/501100011033, FPU16/00980, PTA2017-14779-I and FJC2019-041058-I)
Geochemical records of environmental change in the central Western Interior Seaway during the Cenomanian–Turonian Oceanic Anoxic Event (OAE 2)
Authors: Percival Lawrence , van Helmond Niels , Plint Guy , Papadomanolaki Nina , Gao Yue , Goderis Steven , Claeys Philippe
Published: February 2023

The Cenomanian–Turonian Oceanic Anoxic Event (OAE 2: 94 Ma) marked one of the most severe episodes of climate and environmental change during the Cretaceous Period. The primary feature of this interval was widespread marine anoxia/euxinia, leading to deposition of organic-rich, thinly-bedded, mudstones across the world’s oceans, which in turn caused a pronounced positive shift in δ13C of seawater that is recorded (and characterizes) OAE 2 strata worldwide. The event was also marked by climate warming (with superimposed cooling pulses), biotic stress, and terrestrial perturbations such as increased continental weathering. However, the majority of studied records of OAE 2 were deposited in deep-marine Atlantic and Tethyan settings or European epicontinental basins. Thus, the record of environmental change in other locations or environments is less clear. The Western Interior Seaway (WIS) represented a marine corridor across North America that connected the Arctic and Atlantic marine realms. Thus, understanding the environmental and oceanographic changes in the WIS during OAE 2 is crucial to resolving the wider impact of the event across the global marine realm. Several previous works have focused on sites towards the southern end of the WIS (e.g., Pueblo, Iona Core). In this study, we present a new multi-proxy geochemical dataset from a site in the central–northern part of the Western Interior Seaway: Pratts Landing (western Alberta, Canada). Previous palynological studies have highlighted a southward migration of boreal dinoflagellates during the Plenus Cold Event midway through OAE 2, as well as increased input of terrestrial organic matter. Here, we correlate these data with information from redox, nutrient, and volcanic proxies, and compare the Pratts Landing record with other deep- and shallow-marine records of OAE 2 to gain a wider perspective over the environmental changes that operated in different settings during that time interval. This viewpoint is key for understanding the differences and complexities in how surface phenomena were disturbed during OAE 2, and interpreting geochemical records of different settings during that time interval.
A ~700 years perspective on the 21st century drying in the eastern part of Europe based on δ18O in tree ring cellulose
Authors: Nagavciuc Viorica , Ionita Monica , Kern Zoltán , McCarrol Danny , Popa Ionel
Published: February 2023

Numerical simulations indicate that extreme climate events (e.g. droughts, floods, heat waves) will increase in a warming world, putting enormous pressure on society and political decision-makers. To provide a long-term perspective on the variability of these extreme events, here we use a ~700 years tree-ring oxygen isotope chronology from Eastern Europe, in combination with paleo-reanalysis data, to show that the summer drying over Eastern Europe observed over the last ~150 years is to the best of our knowledge unprecedented over the last 700 years. This drying is driven by a change in the pressure patterns over Europe, characterized by a shift from zonal to a wavier flow around 1850CE, leading to extreme summer droughts and aridification. This is the first and longest reconstruction of drought variability, based on stable oxygen isotopes in the tree-ring cellulose, for Eastern Europe, helping to fill a gap in the spatial coverage of paleoclimate reconstructions (Nagavciuc et al., 2022). Nagavciuc, V., Ionita, M., Kern, Z., McCarroll, D. and Popa, I.: A ~700 years perspective on the 21st century drying in the eastern part of Europe based on δ18O in tree ring cellulose, Commun. Earth Environ., 3, 277, doi:10.1038/s43247-022-00605-4, 2022.
Modelling pyro-convective activity and the meteorological conditions leading to mega-fires
Authors: Campos Cátia , Couto Flavio T. , Purificação Carolina , Filippi Jean-Baptiste , Baggio Roberta , Salgado Rui
Published: February 2023

Mega-fires are wildfires that burn an area greater than 10.000 hectares. Despite being a minority in relation to the total number of fires, they are the one with the greatest negative impact on society and the environment. Associated with this wildfire type, the phenomenon of pyro-convection has been reported in several cases. Strong pyro-convective activity can lead to the formation of clouds within the smoke plume, also known as pyro-cumulus (PyroCu) or pyro-cumulonimbus (PyroCb). In 2017, Portugal recorded 11 mega-fires, of which 8 occurred on the 15th October. Since the photographic evidence of the formation of a PyroCu cloud, the chosen case study was the Quiaios mega-fire. The study aims to simulate the impact of a fire in the atmosphere, as well as the large-scale meteorological conditions that were affecting Portugal during the mega-fires. For this purpose, two numerical simulations were performed using the MesoNH atmospheric model: a coupled simulation with the ForeFire fire propagation model, with 3 nested domains with resolution of 2000m, 400m and 80m (300 by 300 grid points), and a large-scale non-coupled simulation, with a 15km resolution (300 by 250 grid points) to study the large-scale conditions. The coupled simulation allowed identifying the formation of a PyroCu cloud composed by different species of hydrometeors, namely graupel and rain droplets. The pyro-cloud developed inside the plume due the vertical transport of water vapor to higher levels. In the context of large scale, the simulation well represented the evolution of hurricane Ophelia, showing the change in wind direction from Southeast to Southwest in Portuguese territory, which created a favourable condition to the intensification of the active fires and the development of PyroCb clouds during the late afternoon. This study was funded by national funds through FCT-Foundation for Science and Technology, I.P. under the PyroC.pt project (Ref. PCIF/MPG/0175/2019). 
SnoDRI: A Machine Learning Based Index to Measure Snow Droughts
Authors: Rasiya Koya Sinan , Kanti Kar Kanak , Srivastava Shivendra , Roy Tirthankar
Published: February 2023

Snow plays a significant role in the hydrology of numerous regions across the globe. A major portion of precipitation above 45O N latitude falls as snow. The accumulated snow melts slowly and contributes to infiltration and runoff processes. Therefore, studying the quantity and fate of water from snowmelt is essential. Reduced snow storage would lead to snow droughts, which can have an enormous impact on the water resources of snow-dominated catchments, such as those in the western United States. For that reason, it is essential to identify the time and severity of snow droughts efficiently. This study proposes SnoDRI, a new index that could identify and measure snow drought events. SnoDRI is a machine learning-based index estimated from several snow-related variables utilizing novel machine learning algorithms. The model uses a combination of mutual information and a self-supervised learning algorithm of an autoencoder. We use random forests for feature extraction for SnoDRI and to assess the importance of each variable. We use NLDAS-2 reanalysis data from 1981 to 2021 for the Western United States to study the efficacy of the new snow drought index. The results are validated by verifying the coincidence of actual snow drought events and the interpretation of our new index. We will discuss how well the new drought index performs and help in better identification of snow droughts.