bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface climate response to the size and season of northern hemisphere, high latitude, effusive volcanic eruptions
Authors: Zoëga Tómas , Storelvmo Trude , Krüger Kirstin
Published: March 2024

Effusive volcanic eruptions are known to impact climate through the emission of sulphur dioxide and subsequent formation of sulphate aerosols. These aerosols affect radiative transfer in the atmosphere, both directly by scattering sunlight and indirectly through aerosol-cloud interactions. By scattering sunlight, the direct aerosol effect leads to surface cooling. Changes in cloud properties as a result aerosol-cloud interactions, on the other hand, lead to both reflection of sunlight and trapping of outgoing thermal emissions from the ground. Clouds, therefore, have the potential to either cause surface warming or cooling, depending on factors such as the cloud response to the volcanic aerosols and the availability of sunlight.We perform a series of simulations using the Community Earth System Model with the Community Atmosphere Model (CESM2-CAM6) to simulate the climate impacts of northern hemisphere, high latitude, effusive volcanic eruptions. We construct a standard eruption scenario, using the 2014-15 Holuhraun eruption in Iceland as a reference. The Holuhraun eruption released up to 9.6 Tg SO2 over a period of six months, from September 2014 to February 2015, with the emission rate gradually decreasing over time. We apply several different magnitude scalings to this standard scenario and vary the timing of the eruption. This allows us to analyse the climate response as a function of both the eruption size and season.For eruptions starting in winter, we find significant surface warming in our simulations as a result of trapping of outgoing thermal emissions in the absence of sunlight. This warming is mainly confined to the Arctic but also appears over parts of northern Eurasia and North-America, albeit to a lesser extent. This is consistent with our previous work on the Holuhraun eruption where we found evidence for winter surface warming over the Greenland Sea as a result of that eruption, both in model simulations and observations.Conversely, we find surface cooling during summertime eruptions. The spatial distribution of the cooling pattern is different from the winter warming as the cooling predominantly occurs over the Eurasian and North-American continents and is hardly visible in the Arctic. Furthermore, based on preliminary results, whereas the Arctic winter warming is mainly due to aerosol-cloud interactions, the continental summer cooling stems mostly from the direct aerosol effect. Our results indicate a non-linear relationship between the surface air temperature response and the eruption size.
The Environmental Modeling Center Verification System (EVS): Real-time verification of Unified Forecast System (UFS) models
Authors: Levit Jason , Manikin Geoffrey , Bentley Alicia , Dawson Logan , Jensen Tara
Published: March 2024

Currently in the final stages of development, the Environmental Modeling Center Verification System (EVS) is a real-time software system that, once implemented on NCEP supercomputers, will provide verification statistics and graphics for NCEP operational forecast systems. Using the Model Evaluation Toolkit (METplus) suite of verification software, the EVS will use both real-time forecast output and environmental observations to create information on the performance of all NCEP environmental models and products, which are either derived or directly created from the Unified Forecast System (UFS) suite of models. The EVS will generate hundreds of metrics for the suite, which when viewed on EMC webpages will provide a comprehensive and up-to-date overview of the performance of NCEP forecast systems for the general public, model developers, researchers, and decision makers. As EMC works with the international modeling community to develop modeling systems that are based on the Unified Forecast System (UFS), EMC is now evolving towards using the EVS for a single, unified verification software system for real-time verification analysis, evaluation of new and upgraded systems proposed for NWS operations, and as a capability to determine systematic errors and biases that illustrate areas for potential model improvements. This project, led by EMC’s Verification, Post-Processing, and Product Generation Branch (VPPPGB) aims to unify EMC’s verification strategy under one maintainable and supportable software system, and to use performance metrics that have been vetted and peer-reviewed by the UFS community via the Developmental Testbed Center’s 2021 UFS Metrics Workshop. 
Monitoring of floating macro litter in the Arctic seas and rivers
Authors: Pogojeva Maria , Zhdanov Igor , Berezina Anfisa , Kotova Ekaterina , Mikusheva Maria , Kozhevnikov Aleksander , Danilova Eleanora , Yakushev Evgeniy
Published: March 2024

Among other marine environmental problems, the issue of marine litter accumulation in the World Oceans is of increased interest. It is relevant not only in areas with direct intense anthropogenic pressure, but also in remote and presumably pristine areas, such as the Arctic Sea. As the concentration of plastic waste in the marine environment increases, it can have impacts on various components of the marine ecosystem, at sea, on the seafloor, on the coasts and in particular in accumulation areas, while it also can negatively affect human social and economic activities. To reduce the release of plastic debris into the marine environment, litter occurrence and pathways need to be studied in order to identify litter sources, requiring monitoring studies that provide comparable results. Here we present the results of studies of the level of pollution by marine litter floating at sea and flowing with rivers in the Arctic region. Ship-based visual observations at sea were performed in the period 2019-2021 in the White Sea, the Barents Sea, the Kara Sea, the Laptev Sea and the East Siberian Sea. To assess the floating litter input with rivers, regular observations (2 times a month) were carried out by the trained observers on the Northern Dvina and Onega rivers. In all cases a standardized methodology was applied to obtain a unified data and to record the data a Floating Macro Litter mobile application (JRC) was used. The methodology contains a unified list and classification of observed floating sea/riverine litter items, which simplifies the data processing and analysis and allows to compare the data. For the first time a large scale assessment of litter pollution was performed in these remote Arctic regions. The international methodology confirmed the possibility of collecting unified data in the region and at the same time revealed some regional features.
Swiss snow cover in a changing climate: Evaluation of a long-term, high-resolution SWE climatology
Authors: Kotlarski Sven , Danioth Sarina , Gubler Stefanie , Muelchi Regula , Michel Adrien , Jonas Tobias , Steger Christian R. , Marty Christoph
Published: March 2024

Surface snow cover is an important and highly interactive component of global and regional climate systems and has already clearly responded to past warming trends in many regions of the world. Moreover, it is a key ingredient for tourism industry, water supply, irrigation, and hydro-power generation in many mountainous and high-latitude regions. Accurate information about the past, present and future evolution of snow cover is therefore of high importance.In this context, we here present and evaluate a newly developed gridded SWE climatology for Switzerland, available at daily resolution since 1961 and at a 1 km grid spacing. The climatology is based on a variant of the snow cover model of the Operational Snow Hydrological Service (OSHD) of Switzerland, driven by gridded atmospheric input and bias-adjusted towards in-situ snow depth measurements. In accordance with previous works, the analysis shows that the Swiss snow cover has changed strongly over the last decades. The comparison of two climatological long-term periods, 1962-1990 and 1991-2020, in terms of mean September-May SWE and the number of snow days (SWE > 10 mm) within the snow season, reveals a decrease in both indicators over the majority of the country. Low elevations < 1000 m show relative decreases larger than 50% of the mean SWE and larger than 30% regarding the mean number of snow days (about -22 days). The largest absolute difference of mean SWE is found at medium elevations between 1500 and 2000 m with a decrease of about 45 mm (about -26%).The validation of the new snow climatology indicates a high general agreement with in-situ observations and independent remote sensing products. Larger uncertainties and limitations are found at the highest elevations (> 3000 m). They originate from different sources, such as temporal inconsistencies in the gridded input data of the underlying OSHD snow model or the lack of stations at high elevations that are needed for the bias adjustment of the model. Nevertheless, the new snow climatology is able to provide adequate information on past snow cover for Switzerland as a whole and will, among others, serve as a reference for the development of future snow cover scenarios.
Seismological evidence for a multi-fault network at the Ecuadorian subduction interface
Authors: Chalumeau Caroline , Agurto-Detzel Hans , Rietbrock Andreas , Frietsch Michael , Oncken Onno , Segovia Monica , Galve Audrey
Published: March 2024

The simplified view of the subduction interface is that of a single plane along which seismic and aseismic deformation occurs. In reality, however, exhumed subduction zones and geophysical imaging have shown that the seismogenic plate interface is a deformed, 100m-1km thick tabular region. Within this region, we currently do not know if seismic slip is localized on a single fault or distributed over several active faults, and how this impacts seismogenesis and the timing of deformation. Here, we use high-resolution earthquake locations to shed light on these questions.We focus on the aftershock sequence of the March 27th 2022, Mw 5.8 Esmeraldas earthquake which occurred at 19 km depth at the plate interface in Ecuador, and which was recorded by the dense temporary seismic network deployed during the HIPER2 marine campaign. We use machine learning to detect and pick over 1700 earthquakes (Mw 0-3), which we then locate using a double difference algorithm with cross-correlation times and a 3D velocity model. This allows us to obtain an exceptionally detailed image of the seismicity at the plate interface, which falls into a 200-400 m thick zone, comparable to plate interface thicknesses observed in exhumed subduction zones. Using a cross-correlation threshold of 0.75, we extract families of similar earthquakes, whose geometry we investigate using the 3-point method. These families generally occur on subparallel, sometimes superposed planes with a thickness of 0-40 m that is comparable to the thickness of individual fault zones observed within fossil subduction shear zones. These individual fault zones appear to form a network whose geometry impacts the aftershock expansion, itself controlled by afterslip rather than diffusive processes, thus demonstrating the importance of considering the 3D structure of the plate interface when modeling slip.
Assessing the value of information: a comparative analysis of meteorological observation setups in an irrigated German apple orchard
Authors: Schuetze Niels , Kuhnert Lisa , Lennartz Franz
Published: March 2024

Due to climate change, managing irrigation systems requires adapting existing scheduling strategies based on monitoring meteorological, biophysical, and soil physical variables. For monitoring, there are many combinations of sensors, starting from low-cost IoT-based systems and ranging to scientific high-precision devices that offer a specific quality of measurements at a particular price. By explicitly modeling the value gained by more precise monitoring, the value of information (VOI) theory can determine whether additional information provided by site-specific monitoring setups is worth employing to manage the considered irrigation systems. Different levels of information about meteorological conditions are provided by (i) on-site systems (energy balance station, low-cost climate station, and a spatial grid of low-cost LoRaWAN temperature and humidity sensor), (ii) available public weather data, e.g., from a close climate station of the German weather service (DWD), and (iii) latest reanalysis data from the ERA5-Land product. To estimate the additional VOI of the different site-specific monitoring setups related to the reference defined by the DWD data, evapotranspiration, biomass, and yield data simulated by the Aquacrop model are compared. In addition, adapted scheduling strategies are derived using the Deficit Irrigation Toolbox (DIT).   This contribution presents the application of VOI theory for decision-making in the monitoring design of an irrigated apple farm in Werder (Germany) in 2023 and 2024.
Experimental simulation of soil erosion in the context of climate change in NW France.
Authors: Portzer Gabriel , Grimaud Jean-Louis , Marchiol Albert , Stab Olivier , Fleurisson Jean-Alain , Abiven Samuel , Chollet Simon , Maalouf Yara , Khoueiry Nicole , Yadari Neda
Published: March 2024

This study focuses on the evolution of soil erosion rates on artificial covers for low level radioactive waste in the context of climate change. The objective is to test the impacts on erosion of (i) increasing rainfall intensities during storms and (ii) decreasing soil moisture content before storms. The “Centre de stockage de la Manche” (CSM) in Normandy, France, where Low-Level Nuclear waste are stored and monitored for the next centuries, is used as a reference case. There, climatic models anticipate an increase of temperature and seasonality (i.e., dryer Summers and wetter conditions from Fall to Spring) in the next centuries.First, the soils of the CSM are sampled to be characterized. The densities, moisture, grainsize distribution and organic content of the soil are measured. We find that these values are rather homogeneous at the scale of the CSM. Second, a series of experimental rainfall simulations is performed on the CSM soils, focusing of rates and distribution of erosion processes. We simulate rainfall events of decennial, centennial, millennial and decamillennial intensities on 18° slopes, corresponding to the steeper banks of the CSM. Using the capacities of the climatic chambers at the Ecotron Lab in Nemours, France, we further test several soil moistures, i.e., very wet, moderately wet and dry, before simulating rainfall events. Finally, each experiment is repeated several times to assess the “memory” effect of topography on erosion. We quantify erosion by measuring sediment concentrations in run-off water collected at the outlet of the model and using topographic acquisitions performed using photogrammetry.The experimental results are compared with estimations based on the Revised Universal Soil Loss Equation. Some propositions for upscaling, which could be used for assessing hypothetical future increase in soil loss in the CSM, are discussed.
Projections of the large-scale drivers influencing the North Atlantic tropical cyclones
Authors: Goutham Naveen , Omrani Hiba , Collet Lila , Legorgeu Carole
Published: March 2024

Understanding the evolution of tropical cyclones (TC) over the 21st century under a changing climate is essential to improve the resilience of the North American electricity system. In this regard, several studies have projected future changes in TC behavior by detecting and tracking their evolution using climate simulations. One of the key limitations of climate models, specifically attributed to their limited spatial resolution, is that they are unable to simulate all the non-linear interactions between various components of the Earth system. Hence, in this study, instead of tracking TCs in the coarse spatial-resolution climate models, we investigate the evolution of the large-scale drivers influencing the North Atlantic TCs over the mid-future (2041-2060) and far-future (2081-2100). We use five bias-corrected simulations under two shared socio-economic pathway scenarios from the 6th generation Coupled Model Intercomparison Project. In particular, we examine the changes in the large-scale thermodynamic and atmospheric dynamic indicators favorable for TCs, namely sea surface temperature, wind shear, and lapse rate. Our results show an increase in the seasonal mean North Atlantic sea surface temperature (between +1 and +3°C), the length of the TC season (between +2 and +5 months), and the ocean heat content (3-6 times) relative to the historical period (1995-2014), while a decrease in the temperature lapse rate (between -0.8% and -1.45%) over both the mid-future and far-future. We find no significant changes in the vertical wind shear under a changing climate. These results suggest an increase in both the frequency and intensity of TCs over the North Atlantic, the latter by 2.6%-5.2% on average. Additionally, our results show a plausible reduction in the conditions favorable for TCs by mitigating from high-emission to moderate-emission scenarios.
Emergence of North Atlantic Deep Water during the Cenozoic: A Tale of Geological and Climatic Forcings
Authors: Pineau Erwan , Donnadieu Yannick , Maffre Pierre , Lique Camille , Huck Thierry , Ladant Jean-Baptiste
Published: March 2024

The modern thermohaline circulation in the Atlantic Ocean plays a crucial role in shaping the climates of Europe and North America. It also significantly influences ocean carbon storage and biological productivity through processes such as deep ocean ventilation and nutrient advection. A pivotal element of this intricate circulation system is the deep convection in the North Atlantic, which is essential for the Atlantic meridional overturning circulation. Paleogeographic studies based on data from the Cenozoic era propose that the establishment of this ocean conveyor belt occurred between the Middle Eocene (approximately 48 to 38 million years ago) and the Late Miocene (around 11 to 5 million years ago). This period witnessed significant climate fluctuations, notably exemplified by the Eocene-Oligocene transition (34 million years ago), marked by a sudden global temperature cooling and the emergence of the Antarctic Ice Sheet (AIS). Did these changes have a significant impact on the stability of the North Atlantic Ocean? To address this question, we investigate the mechanisms behind the initiation of deep water in the North Atlantic during the Eocene to Miocene transition, using the Earth System model IPSL-CM5A2. Our Eocene simulation indicates an absence of convective instabilities in the North Atlantic, whereas deep convection is evident in our Miocene simulation, enabling the presence of a proto-Atlantic Meridional Overturning Circulation (AMOC) cell. In order to investigate the processes triggering North Atlantic Deep Water (NADW) initiation under Miocene conditions, we conducted sensitivity tests involving a reduction in atmospheric CO2 concentration from 1,120 ppmv to 560 ppmv and the introduction of AIS for Eocene conditions. Our findings reveal that halving the CO2 concentration and initiating AIS during the Eocene is insufficient to destabilize the water column in the North Atlantic and instigate the formation of NADW. The Eocene paleogeography emerges as a key factor, contributing to an inflow of fresh water into the Atlantic Ocean, resulting in low surface water density. This process reinforces stratification, hindering the onset of convection.
Large-scale green grabbing for wind and solar PV development in Brazil
Authors: Klingler Michael , Ameli Nadia , Rickman Jamie , Schmidt Johannes
Published: March 2024

Large-scale wind and solar photovoltaic (PV) infrastructures are rapidly expanding in Brazil. These low-carbon technologies can exacerbate land struggles rooted in historical inequities in land ownership, lack of regulation and weak governance. Here, we trace how green grabbing, i.e. the large-scale appropriation and control of (undesignated) public lands, both formally legal and illicit, for the development of wind and solar PV, has developed in Brazil throughout 2000 to 2021. We find that global investors and owners, mainly from Europe, are involved in 78% of wind and 96% of solar PV parks, occupying 2,148 km2 and 102 km2 of land, respectively. We also show that land privatization is the prevalent land tenure regime for securing access to and control over land, indicating significant transformations of prior (undesignated) public and common land. We conclude that green grabbing is a persistent, critical phenomenon in Brazil, requiring transparency and vigilant monitoring of land claims and tenure modifications.
Urban Flood Classification in SAR Images
Authors: Mayo Rotem , Ikan Tal , Gerzi Rosenthal Adi
Published: March 2024

Detecting flooding in Synthetic Aperture Radar (SAR) satellite imagery is crucial for the ability of Google’s flood forecasting team to train predictive models and identify regions at risk of flooding, making it possible to give prior warning to people in soon to be flooded areas.  However, flood detection in urban areas is currently very poor, preventing the extension of these advanced warning systems to large parts of the population. This is a long known challenge in the field of flood detection using remote sensing methods. In this study, we discuss a possible method to overcome this problem.SAR satellites are preferred for flood monitoring due to their effectiveness regardless of weather or environmental conditions. They operate by sending pulse signals to Earth and measuring the reflected backscatter. Smooth surfaces like water typically reflect signals away, appearing darker in SAR images. However, in urban areas, the 'Double Bounce' effect caused by 90-degree surfaces, causes larger backscatter, making water detection challenging.Our methodology involves analyzing abnormally bright pixels in urban areas, attributed to the amplification of the double bounce effect by flooding. We deviate from the traditional thresholding per image approach used in rural settings, instead focusing on the historical brightness levels of each pixel separately to identify significant deviations. We then aggregate the data over large urban areas to infer potential flooding.We optimize and evaluate the model using a train-validation split of a dataset consisting of approximately 70 urban flood events, manually curated from news stories and paired with corresponding SAR images. The evaluation, which compares these images with randomly selected images, yields a precision of 86% and a recall of 62%.  Acquiring high quality ground truth data proved to be one of the big challenges in this project, and we are currently working on other ways to evaluate the model and improve its accuracy.These results demonstrate the potential of using SAR images for urban flood classification by focusing on the unique characteristics of urban areas, such as the double bounce effect. This method shows promise in providing alerts and forecasts for urban regions, a crucial need for disaster management. Further research and more accurate ground truth data could enhance the effectiveness and accuracy of detecting urban floods through SAR images.
The thermohaline stream function in a changing climate
Authors: Jung Verena , Döös Kristofer
Published: March 2024

The thermohaline stream function is a powerful tool to analyse water mass transformation (WMT). Traditionally, the meridional overturning circulation is visualised in geographical coordinates with stream functions as a function of latitude whereby the meridional velocity is zonally integrated. Conversely, in the thermohaline framework the entire global ocean is represented in oceanographic well-established coordinates namely absolute salinity and potential temperature. This allows to analyse WMT between cold and warm as well as saline and fresh waters in one single graph. It is generally constituted of a tropical cell, a conveyor belt and a polar cell. Here, we present stream functions from various CMIP6 climate scenarios computed by the EC-Earth model and compare pre-industrial, present-day and climate scenario simulations to study changes in WMT. We further provide background information on how the thermohaline stream function (left panel of the attached Figure) is motivated physically and computed mathematically using Helmholtz decomposition. This allows us to identify sources and sinks of mass in the corresponding thermohaline tendency potential, as shown in the right panel of the attached Figure. The position in the temperature and salinity space of the overturning cells reveal significant differences in the climate scenarios, as well as  differences in the mass sources and sinks revealed by the tendency potentials. These sources are due to the fresh water fluxes through the sea surface  and for the data assimilation data sets, they are also due to mass, heat and salt sources and sinks withing the ocean subsurface domain.Fig: The thermohaline stream function (left panel) and tendency potential (right panel) computed using data from the ocean component of an EC-Earth model (present-day simulation coloured in red and blue, SSP585-simulation in grey contour lines). They capture the entire ocean circulation in two figures describing the water mass transformation in temperature and salinity.
Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field
Authors: Wang Xiangyu , Zhang Qinghe , Wang Chi , Zhang Yongliang , Tang Binbin , Xing Zanyang , Oksavik Kjellmar , Lyons Larry R. , Lockwood Michael , Zong Qiugang , Li Guojun , Liu Jing , Ma Yuzhang , Wang Yong
Published: March 2024

Open magnetic flux in the polar cap almost completely disappeared and the Earth's magnetotail was compressed into a calabash shape during the 9th April 2015 coronal mass ejection, according to magnetohydrodynamic simulations and observations from DMSP and THEMIS.The Earth's magnetosphere is the region of space where plasma behavior is dominated by the geomagnetic field. It has a long tail typically extending hundreds of Earth radii (R-E) with plentiful open magnetic fluxes threading the magnetopause associated with magnetic reconnection and momentum transfer from the solar wind. The open-flux is greatly reduced when the interplanetary magnetic field points northward, but the extent of the magnetotail remains unknown. Here we report direct observations of an almost complete disappearance of the open-flux polar cap characterized by merging poleward edges of a conjugate horse-collar aurora (HCA) in both hemispheres' polar ionosphere. The conjugate HCA is generated by particle precipitation due to Kelvin-Helmholtz instability in the dawn and dusk cold dense plasma sheets (CDPS). These CDPS are consist of solar wind plasma captured by a continuous dual-lobe magnetic reconnections, which is further squeezed into the central magnetotail, resulting in a short "calabash-shaped" magnetotail.
Next generation atmospheric chemistry modeling with the Multiscale Infrastructure for Chemistry and Aerosols (MUSICA)
Authors: Pfister Gabriele , Barth Mary , Emmons Louisa , Dawson Matthew , Tang Wenfu , Smith Warren , Vitt Francis , Skamarock Bill
Published: March 2024

This presentation gives an overview of the Multiscale Infrastructure for Chemistry and Aerosols (MUSICA), which is taking a fundamentally new approach to modeling and will become the next-generation community infrastructure for research on atmospheric chemistry and aerosols. MUSICA will move atmospheric chemistry modeling towards a unification of the range of scales inherent in the Earth System, allowing for the exploration of the couplings across space, time and ecosystems in a consistent manner. It follows modern software standards and is designed to be able to connect to any atmosphere model. Its capability to unify various spatio-temporal scales, coupling to other Earth System components, and process-level modularization will allow advances on topics ranging from fundamental atmospheric chemistry research to air quality to climate and couplings between ecosystems. Two versions of MUSICA are currently available, both a configuration of the Community Earth System Model (CESM) using the Community Atmosphere Model (CAM) coupled with tropospheric and stratospheric chemistry. Both versions enable global simulations with regional refinement capability. MUSICAv0 uses a hydrostatic Spectral Element dynamical core and is suitable for scales of ~5 km or higher whereas MUSICAv1 uses the non-hydrostatic Model Prediction Across Scales (MPAS) dynamical core enabling studies of regions at local scales (
Spatial signatures of flooding and blocking are related on the long-term scale
Authors: Hernandez Diego , Lun David , Bertola Miriam , Ahrens Bodo , Blöschl Günter
Published: March 2024

Process-based explanations of flood controls have increasingly advanced in the last years along with comprehensive datasets availability. However, the relationship on the long-term scale between floods and large-scale atmospheric drivers remains unclear, hindering the understanding of flood-prone periods and the projections of flood change. The translation of atmospheric blocking (i.e., a persistent mid-latitude high-pressure system that blocks westerly flows) into flooding has not been raised for large samples due to the spatiotemporal complexity of the atmospheric and hydrological response. For the 1950-2010 period, this study analyzes summer flood events from a pan-European database, a gridded binary blocking index derived from ERA20C, and hemispheric fields of four meteorological variables from ERA5. By defining a window of days with flooding (dF) related to precipitation surpluses in central Europe, days with blocking (dB) at three different regions namely North Atlantic (NATL), Europe (EU) and Scandinavia (SCAN), and days with simultaneous flooding and blocking (dFxB), our results indicate spatially similar meteorological signatures for dF and dFxB at NATL, but different patterns between dB and dFxB at NATL, suggesting there is a subset of blocking events at NATL controlling the meteorological signature of flood events in central Europe. Patterns for dB and dFxB at SCAN are similar implying that blocking in the SCAN region has the most direct effect on floods in central Europe. Hence, this research could provide new insights into large-scale atmospheric controls and sources of predictability regarding floods.
A Contactless Rapid Rating Curve Assessment Based On Drone-borne Measurement
Authors: Hu Xinqi , Tuo Ye , Broich Karl , Merk Fabian , Disse Markus
Published: March 2024

Rating curve relationship is vital to hydrological studies, such as flood control and other water-related decision-making processes. Traditionally, rating curve are estimated by using single- or multiple-gauging observations, which is time-consuming, costly, and lacks spatial resolution. Hydraulic models are usually a reliable method to quickly derive the stage-discharge relation for discharge estimation, especially for assessing more reliable high-flow rating relations in extrapolation beyond gauge observation. To establish such models, hydraulic parameters such as water surface elevation, bathymetry, and bed roughness are needed, but they are mostly not available in remote and inaccessible regions. Drone-borne hydrometric monitoring technologies can be deployed to address this problem.As one of the primary objectives of the Horizon Europe UAWOS project, which is dedicated to developing an Unmanned Airborne Water Observing System for providing key hydrometric variables at high spatial resolution/coverage, and data-based products/services to enhance management and decision-making, this work centers on integrating hydraulic modeling with the unmanned airborne water observing system to establish the rating curve relationship. Water surface elevation data is derived by radar altimetry, bathymetry data by water penetrating radar and sonar, and Doppler radar for surface velocity. By utilizing the surface velocity and water surface elevation data, in conjunction with shallow-water equations, a bathymetry estimation algorithm is used to interpolate the bathymetry from the observed cross-section to the whole simulated river channel. We also come up with a method to directly retrieve the river roughness parameter from the UAV drone observation data.As a whole, these methods collectively establish a framework that is easily to use to estimate the rating curve in remote regions. The study shows how information from high spatial resolution and coverage hydrometric variables derived by drone-borne hydrometric monitoring technologies can improve rating curve estimates from models.
Source apportionment of PM10 carbonaceous aerosol collected in Hungarian cities, using tracer analytical methods
Authors: Major István , Kertész Zsófia , Angyal Anikó , Furu Enikő , Papp Enikő , Vasanits Anikó , Bán Sándor , Molnár Anita , Gergely Virág , Molnár Mihály
Published: March 2024

The environmental and health-damaging effects of “high aerosol concentration” periods often represent an issue in Hungary, which is mainly due to the country's location (basin is within the Carpathians). The main sources of carbonaceous aerosol are already more or less known, but the numerical extent and temporal distribution of the contributions are still the subject of numerous investigations in the region. In these researches, isotopic analytical procedures are increasingly involved, which, in addition to traditional analytical methods, enable us to make more and more accurate source apportionment analyses. By means of the radiocarbon method, the modern and fossil fuel sources can unambiguously be separated, while levoglucosan can be used as tracer to distinguish the two largest modern sources i.e. biological emissions and anthropogenic wood burning. In the first half of 2015, a comprehensive PM10 collection campaign in five big cities (Budapest, Debrecen, Miskolc, Pécs, Nyíregyháza) was completed, financed by the Hungarian state. Its purpose was to identify the most relevant emission sources and quantify their contributions as accurately as possible. In the course of the analyses, mass concentration of the total, organic and elemental carbon (TC, OC, EC, respectively) of the collected samples were determined, in addition, the specific 14C activity and levoglucosan concentration of TC were also measured. Our studies clearly revealed the predominance of the anthropogenic wood burning source in the winter/heating period, but the contribution of biological sources ranged in a broader scale during the observation period. Contrarily, the contributions from fossil sources were relatively balanced for the same period.
School teachers as partners in a disaster risk reduction context: challenges and benefits highlighted by Mayotte case study in France
Authors: Le Vagueresse Louise , Devès Maud
Published: March 2024

Scientists working on natural hazards and associated risks play a key role in population information with respect to disaster risk reduction. But they are not always familiar with the socio-cultural and informational contexts of at-risk communities, and identifying the right local partners and intermediaries can be a tricky and time consuming process. Sendai Framework and recent studies target school teachers as relevant mediators for disaster risk education and scientific information. Here, we document and analyze the experience of school teachers’ during the 2018 seismo-volcanic crisis in Mayotte, France and discuss the benefits and challenges of taking them as partners to better inform at-risk communities during and prior to a crisis. Mayotte case study is interesting because it corresponds to a multi-cultural context. It is an oversea French department characterized by important socio-cultural differences from mainland France, multilingualism, low levels of literacy and precarious living conditions (see Roinsard, 2014). Following the start of an unexpected seismic crisis in May 2018, submarine volcanism was discovered between 5 and 50 km off the east coast of this island where, in living memory, there had never been any volcanic activity. However, this discovery occurred in May 2019, a year after the first earthquakes worried the communities. The first months of the crisis were marked by major scientific uncertainties and a perceived lack of information from the inhabitants’ perspective (Fallou et al., 2020; Devès et al., 2022). Our study is built on 14 semi-directive interviews with school teachers and 18 focus groups with schoolers. This comprehensive set of qualitative data allows us to discuss the role of school teachers as intermediaries to spread information between scientists and at-risk communities, prior and following natural events.
What controls the migration rate of divides? Insights from morphometry and 10Be and 26Al cosmogenic nuclides analysis applied to the Vosges massif
Authors: Mathieux Bastien , van der Woerd Jérôme , Chabaux François , Steer Philippe , Carcaillet Julien , Perrone Thierry
Published: March 2024

The Vosges massif is a mid-altitude mountain range located northeast of France. It extends latitudinally for 250 km north of the Alps and is characterized by topographic, geological and geomorphological north-south and east-west gradients. In the south, the exhumed Paleozoic basement culminates at about 1400 m asl while in the north, river valleys incise Mesozoic sandstones with summits ranging between 400 and 700 m asl. The relief is intricately linked to the Eocene-Oligocene formation of the Rhine graben and the Mio-Pliocene deformation of the Alpine foreland. The present-day slow deformation rates in the Rhine graben, coupled with the region’s moderate seismicity characterized predominantly by strike-slip mechanisms, raise questions about the current driving forces behind the Vosges’ topographic evolution.The evolution of drainage divides provides a window into the complex interrelations among tectonic forces, surface erosion processes and climatic influences that contribute to shaping a mountain range. In this study, we combine morphometric and cosmogenic nuclides (10Be and 26Al) analyses to assess the migration of the Vosges’ main drainage divide. Gilbert’s metrics (elevation, relief and gradient) alongside χ-index reveal a strong eastward gradient across the divide suggesting a migration away from the Rhine graben margin. To provide a quantification of this migration, a dataset of in-situ cosmogenic nuclides whose concentrations are erosion-dependent has been measured in samples collected across various segments of the divide. Cosmogenic nuclide analysis reveals a robust set of 10Be/26Al ratios falling within the steady-state denudation curve and denudation rates, ranging from 30 to 90 mm/kyr in the south and 40 to 70 mm/kyr in the north. Notably, both regions display an eastward trend in denudation, corroborating the gradient observed in the morphometric analysis.  A geometric approach was used to translate cross-differences in denudation rates and topographic gradients into migration rates of the main drainage divide, showing a westward shift of 20-70 mm/kyr in the south and 3-30 mm/kyr in the north.Expanding our analysis, we examined the correlation between the calculated denudation rates and the hilltop curvatures derived from high-resolution DEMs (1m). A relation appears in the south, whereas no relationship has been found in the north, suggesting additional complexities in controlling morphogenetic processes. This finding allows us to use hilltop curvature as a proxy for denudation rates, particularly within mono-lithologic soil-mantled basins along the southern Vosges drainage divide. These insights offer a valuable conceptual framework for constraining numerical simulations at the mountain range scale aimed at unravelling the external forces that shape the highest Vosges relief.
Global cloud-to-ground lightning data to inform wildfire ignition patterns
Authors: Brambleby Esther , Veraverbeke Sander , Mataveli Guilherme , Joshi Manoj , Jones Matthew
Published: March 2024

Lightning is recognised as a crucial wildfire ignition source worldwide, especially in remote regions including boreal and temperate forests where large carbon stocks are held. The societal consequences of these wildfires, as well as their contribution to climate change, can be immense. The occurrence of lightning is projected to increase in these areas under climate change, however robust assessments of lightning contribution to wildfire risk have been restricted to selected regions due to the narrow spatial extent of cloud-to-ground lightning records. Consequently, evaluations of lightning-fire relationships using existing global lightning observational datasets have been limited to considering the total amount of lightning. Only cloud-to-ground lightning can ignite a wildfire, therefore when considering impacts on wildfire risk it is essential to distinguish between lightning types.Using Vaisala’s unique Global Lightning Dataset (GLD360), which discriminates between cloud lightning and cloud-to-ground lightning strikes, we present our preliminary analyses of the spatial patterns and seasonality of cloud-to-ground lightning. Here, we show the regional variation in the lightning frequency and the cloud-to-ground fraction, as well as the strength (current) and polarity of cloud-to-ground lightning strikes.By considering cloud-to-ground lightning strikes only, we characterise the spatial and seasonal variation in lightning events with the potential to ignite wildfires. Combining global observations of lightning strikes with observations of individual fires and coincident meteorology will advance our mechanistic understanding of wildfire ignition potential in a range of weather conditions, improve the process representation of the ignition process in global models, and refine projections of changing wildfire risks under climate change.
From tree to plot: investigating stem respiration and its drivers along a logging gradient in Sabah, Malaysian Borneo
Authors: Mills Maria Barbara , Both Sabine , Jotan Palasiah , Huaraca Huasco Walter , Cruz Rudi , Pillco Milenka M , Burslem David F. R. P , Maycock Colin , Malhi Yadvinder , Ewers Robert M , Berrio Juan Carlos , Kaduk Jörg , Page Susan , Robert Rolando , Teh Yit A , Riutta Terhi
Published: March 2024

Respiration by trees stems constitutes a substantial proportion of autotrophic respiration in forested ecosystems and has been estimated to contribute 12 – 25 % of total ecosystem respiration, yet little is known about its associated drivers at different spatial scales. Stems are the largest contributor to forest biomass and so the respiratory consumption of stems has the potential to considerably affect carbon budgets in forest communities. As logged and degraded forests are fast becoming the most dominant land-use type throughout the tropics, it is also important to contextualise stem respiration over land use gradients. In this study we quantified stem respiration at individual tree and plot scales in nine 1-ha plots over a gradient of heavily logged to old-growth forest in Malaysian Borneo. We investigated how logging intensity, forest structure, plant functional traits, and soil chemistry influence stem respiration in logged and old-growth forest plots at both scales. We found that, at individual tree level, stem respiration rate per unit stem area was significantly higher in logged than old-growth plots, and this was consistent within most diameter classes. At the 1-ha plot scale, however, total stem respiration did not differ between forest types: the higher stem respiration rate in logged plots was offset by the higher stem area in old-growth plots. At plot level, stem respiration was driven by forest structure and soil chemistry. We found that basal area was a strong predictor of stem respiration within both forest types at plot scale; for a similar basal area, logged plots exhibited a higher stem respiration rate. Partitioning stem respiration into its growth and maintenance components at plot scale highlighted how logged plots prioritise growth in response to intense light competition, as logged plots had significantly higher allocation to growth respiration, whereas old-growth plots prioritised maintenance and cell structure. Our analysis at individual tree scale reinforced these differing priorities, as stem respiration in logged plots was driven by plant traits associated with growth and wood anatomy, as opposed to within old-growth plots where stem respiration was driven by traits associated cell structure and maintenance. These results reflect the different strategies of resource allocation for trees growing in logged and old-growth plots and adds to the growing body of research on autotrophic respiration, the least studied component of forest carbon dynamics within a very understudied yet expanding land use.
Tracking sediment transport through the Miage Glacier, Italy, combining a Lagrangian approach with luminescence burial dating of englacial clasts
Authors: Margirier Audrey , Rowan Ann , Brondex Julien , King Georgina E. , Schmidt Christoph , Egholm David L. , Pedersen Vivi K. , Watson C. Scott , Veness Remy , Anderson Leif , Lehmann Benjamin
Published: March 2024

 Constraining the pathways and time scales of englacial sediment transport is of primary importance for both understanding the processes that move sediment through glacierised catchments and quantifying the response of mountain glaciers to climate change. However, sediment transport through glaciers is a more complex process than ice flow and difficult to observe; clasts can be transported englacially and at the ice margins, but also deposited into moraines before being re-entrained into englacial transport.We developed a novel method taking a Lagrangian approach that combines luminescence rock surface burial dating of the time for englacial transport of individual rock debris with ice-dynamical glacier evolution modelling of glacial sediment transport to quantify rates of sediment transport through the Miage Glacier catchment in the Italian Alps. Luminescence rock surface burial dating allows determining the burial duration of rocks after they have been exposed to sunlight, but this method has not previously been applied to englacial clasts.We obtained luminescence ages for seven samples embedded in the ice in the ablation zone of Miage Glacier, with burial ages ranging from 0.2 ± 0.1 ka to 5.0 ± 1.4 ka. Samples collected in the upper part of the ablation zone yield younger ages than samples collected near the terminus. The younger luminescence ages (0.2 ± 0.1 ka and 0.3 ± 0.1 ka) are consistent with expected burial duration based on the present-day glacier velocity. In contrast, older luminescence ages obtained for samples located in the lower part of the ablation zone (1.2 ± 0.1 ka to 5.0 ± 1.4 ka) show that these samples record a longer and more complex burial history, suggesting that these samples were either stored in the headwall area or within moraines for several thousand years before being entrained in the ice. In the Miage catchment, debris could have been stored in a moraine at the junction between the Bionnassay Glacier and the Dome Glacier before being entrained in the Miage glacier. We compare the burial ages of the englacial clasts with simulations of glacial sediment transport using a Lagrangian particle tracking scheme in the glacier model iSOSIA. The model results illustrate the range of englacial and subglacial sediment flow paths through the Miage Glacier and simulate similar durations of englacial transport to those obtained for our luminescence samples.