bluuebunny/crossref_metadata_2025 huggingface dataset:
Stadial to interstadial hydrographic changes in the northern Nordic Seas 
Authors: Risebrobakken Bjørg , Blindheim Dang Inge , Tisserand Amandine , Wong Wanyee , Kryk Adrian , Bąk Małgorzata
Published: March 2024

New multiproxy records informing in unprecedented detail on hydrographic changes in the northernmost Nordic Seas during Dansgaard-Oechger events, will be presented. An extensive sea ice cover and a homogenous intermediate water mass have been suggested to characterize the Nordic Seas during stadials, based on records from the southern Nordic Seas. Combined planktic and benthic oxygen and carbon isotopes informing on water mass stratification and ventilation, supplemented by planktic Mg/Ca, planktic and benthic foraminiferal abundance, Ice Rafted Debris, diatom, and biomarker data suggests, however, less stable stadial water column conditions in the Fram Strait. The stadial to interstadial transitions are characterized by a series of short living changes in productivity, water mass characteristics and IRD deposition. The new records from the Fran Strait will be see in context of comparable records from other sites in the Nordic Seas. Implications of the new results will be discussed.
Optical observations of needles evolving into negative leaders in a positive cloud-to-ground lightning flash
Authors: Wu Bin , Qi Qi , Lyu Weitao , Ma Ying , Chen Lyuwen , Rakov Vladimir
Published: March 2024

High-speed video records of a single-stroke positive cloud-to-ground (+CG) flash were used to examine the evolution of eight needles developing more or less radially from the +CG channel. All these eight needles occurred during the later return-stroke stage and the following continuing current stage. Six needles, after their initial extension from the lateral surface of the parent channel core, elongated via bidirectional recoil events, which are responsible for flickering, and two of them evolved into negative stepped leaders. For the latter two, the mean extension speed decreased from 5.3 × 10^6 to 3.4 × 10^5 and then to 1.3 × 10^5 m/s during the initial, recoil-event, and stepping stages, respectively. The initial needle extension ranged from 70 to 320 m (N = 8), extension via recoil events from 50 to 210 m (N = 6), and extension via stepping from 810 to 1,870 m (N = 2). Compared with needles developing from leader channels, the different behavior of needle flickering, the longer length, the faster extension speed, and the higher flickering rate observed in this work may be attributed to a considerably higher current (rate of charge supply) during the return-stroke and early continuing-current stages of +CG flashes.
Opportunities and limitations of hyperspectral and multispectral data fusion for monitoring biodiversity
Authors: Mileva Nikolina , Paganini Marc , Fernandez Diego
Published: March 2024

The increasing number of hyperspectral sensors have opened the path to more widespread application of imaging spectroscopy. While hyperspectral data is currently not available on a global scale, the upcoming SBG and CHIME missions will fill this gap collecting images with a ground sampling distance of 30m over the globe offering unprecedented abilities to observe biological diversity on Earth. Coupling this data with existing multispectral time series can give us a glimpse into how biodiversity has changed in the last decades marked by the sixth mass extinction. The purpose of our research is to explore the use of hyperspectral and multispectral data for measuring biodiversity indicators, determine their limitations in terms of spatial and spectral resolution and how these affect biodiversity measures. We calculate alpha and beta diversity using the recently developed biodivMapR R package with a set of images from Sentinel-2 and EnMAP. Subsequently, several methods representing the state of the art in fusion are selected to create a compound product with higher spatial and spectral resolution. This new product is used as an input for calculating alpha and beta diversity elaborating on the discrepancies and similarities with the previous estimates. To validate the results, we make a link between “spectral” diversity and the actual number of species observed taking into account in-situ data of well studied biodiversity supersites. The outcome of this study will help us evaluate the feasibility of creating a new Earth observation based product for monitoring biodiversity.
Assessing the biodegradability of dissolved organic carbon in freshwater systems: A method evaluation study
Authors: Green Danielle , Rezanezhad Fereidoun , Smith Scott , Slowinski Stephanie , Van Cappellen Philippe
Published: March 2024

Dissolved organic carbon (DOC) is an important contributor to both carbon cycling and other biogeochemical processes in aquatic ecosystems. The biodegradable fraction of DOC can be microbially degraded over time, producing carbon dioxide (CO2), a greenhouse gas. In addition, microbial degradation-resistant DOC can accumulate in water bodies, causing chemical and physical changes to aquatic systems. Although biodegradable DOC (BDOC) is widely studied, there is no agreed-upon standard method for assessing its biodegradability. Here, we aimed to develop and evaluate a new method for determining BDOC in freshwater samples. Our method includes filtering water samples to below 0.22 µm, to remove existing microbial cells, prior to inoculating the samples with a concentrated microbial inoculum produced by stepwise isolation of microbial cells from a peat sample. In addition, we added solutions containing nitrogen and phosphorus (in the forms of NH4NO3 and K2HPO4, respectively) to ensure that the microbes were not nutrient-limited. The samples were then capped with foam stoppers and incubated in the dark at 25⁰C on a shaker for 28 days to allow constant aeration during BDOC degradation. When applied to five freshwater samples collected from rivers, stormwater ponds, and a lake, and a glucose control, we observed that the amount of BDOC in the natural samples ranged from 15% to 53% and was 90% in the glucose control. Rates of BDOC degradation were calculated from DOC measurements at six sampling time points between days 0 and 28. We found that the DOC trends with time were best explained by two successive phases for BDOC degradation in all of the samples: an initial, fast, phase of BDOC degradation followed by a second, slower, phase of BDOC degradation where the rate constant for the second phase was between 5.57 and 565 times slower than for the initial phase. Changes in chemical characteristics of DOC measured using absorbance and fluorescence parameters including specific ultraviolet absorbance at 254 nm (SUVA254), humification index (HIX), and parallel factor analysis (PARAFAC) at each sampling time revealed that the initial, fast, phase of BDOC degradation often represents the utilization of small, non-aromatic compounds while the later, slower, phase of BDOC degradation often represents the utilization of more complex, aromatic compounds. The presented method provides a new approach to measure and characterize BDOC degradability and degradation kinetics that can be applied to future studies on biogeochemical processes in aquatic ecosystems.
Constraints on the Formation Age of the Chukchi Basin, Arctic Ocean, inferred from Marine Heat Flow Measurements
Authors: Kim Young-Gyun , Hong Jong Kuk , Jin Young Keun , So Byung Dal
Published: March 2024

The Amerasia Basin, one of two major basins that comprise the Arctic Ocean, is thought to have a more complex formation history than its counterpart, the Eurasian Basin. Because the harsh conditions for marine expeditions last the entire year, there is a lack of observational data for constraining the tectonic history of the Chukchi Basin. Thus, there are multiple existing hypotheses for its tectonic history, with contrasting formation ages ranging from Mesozoic to Cenozoic and crustal types ranging from hyper-extended continental crust to oceanic crust. Recently, during the 2018 and 2021 Arctic expeditions of the Korean ice-breaking research vessel Araon, we obtained the new marine heat flow data along the east-west and northeast-southwest transect lines from the abyssal plain to the continental slope/shelf of the basin. These data may play an important role in constraining the formation age of the basin, as the extending axis among the hypotheses is likely oriented from north-south. Assuming an oceanic crust, the formation age can be inferred to be Late Cretaceous. This information concerning the formation age enhances our understanding of the underestimated complex tectonic history of the Amerasia Basin, because such inferred timing aligns with the formation age of the adjacent Chukchi Borderland.
Heatwaves and Droughts in Europe: A multi-year analysis using MODIS Land Surface Temperature Anomalies
Authors: Karinou Foteini , Agathangelidis Ilias , Cartalis Constantinos
Published: March 2024

In recent decades, European societies and ecosystems have faced recurrent extreme temperatures that contribute to a significant number of impacts, such as wildfires, heat-related illnesses, and crop losses. As heat extremes are further projected to increase in frequency and intensity, a better understanding and close monitoring of these events is necessary. In this study, remotely-sensed Land Surface Temperatures (LSTs) from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to assess recent heatwaves and droughts in Europe (2003 – 2023). Our results reveal that surface heat extremes are intensifying and becoming more frequent. Moreover, a strong coupling is found between surface thermal extremes, heatwaves (based on near-surface air temperatures) and droughts. Finally, surface LST anomalies are investigated in the context of shifts in energy partitioning under heatwaves/droughts, using eddy covariance flux measurements from the Integrated Carbon Observation System network.
Towards a unifying approach of land degradation in Europe
Authors: Pravalie Remus , Borrelli Pasquale , Panagos Panos , Niculiță Mihai , Bandoc Georgeta , Patriche Cristian , Roșca Bogdan
Published: March 2024

The impact of land degradation on the environment is multidimensional and is fundamentally influenced by various land degradation processes, which usually interact spatially in a convergent manner. However, the spatial pattern of multiple converging (co-occurring) land degradation pathways remains largely unexplored in Europe. To address the synergistic (convergent) nature of land degradation, in this work we modelled and mapped the spatial pattern of twelve interacting processes in agricultural/arable environments of Europe. Therefore, using state-of-the-art and large-scale datasets that were modelled via appropriate GIS (Geographic Information System) techniques, we performed an unprecedented investigation on land multi-degradation in 40 European countries. Essentially, we found that up to 27%, 35% and 22% of pan-European agricultural/arable landscapes are synergistically affected by one, two and three land degradation processes, while 10–11% of continental agricultural/arable environments are cumulatively threatened by four and at least five co-occurring processes. Our multi-process framework can be a valuable scientific tool for complex modelling of land degradation, but also for applying various agricultural, climate or sustainable development policies at European level.
Operational Landslide Early-Warning Systems (LEWS) in Italy
Authors: Marchesini Ivan , Rossi Mauro , Peruccacci Silvia , Brunetti Maria Teresa , De Stefanis Pietro , Solimano Monica , Esposito Rosaria , Agostino Ivan , Loddo Stefano , Cinus Salvatore , Valgimigli Giovanni , Corazza Angelo
Published: March 2024

In recent years, Landslide Early Warning Systems (LEWS) have garnered increasing attention, both from the scientific community and from professionals engaged in prevention, monitoring, and forecasting activities.However, the extensive scientific literature on the subject primarily focuses on the development of algorithms, methods, and experiments. This literature often falls short in bridging the significant gap between the theoretical design of an early warning system and its actual operational deployment (though exceptions exist, as indicated by Guzzetti et al. 2020). This disparity poses a pivotal challenge in the sector. An effective system transcends mere theoretical algorithmic creation; it necessitates, among other factors, a pragmatic understanding of end-user requirements, a seamless and continuous operational framework, and efficient communication tools.The Institute for Geo-Hydrological Protection Research of the National Research Council (IRPI CNR) has pioneered the domain of geographical LEWS in Italy. By managing five regional and national-scale geographical LEWS in collaboration with the National Civil Protection and the national railway network operator, IRPI CNR has highlighted the practical significance of these systems. The institute has developed solutions tailored to provide decision-support tools aligning with diverse stakeholders' needs.This contribution aims to illustrate how scientific research outcomes can be leveraged, transforming them into operational tools in line with decision-makers' requirements. The presentation offers a detailed overview of real-world use cases of LEWS administered by IRPI in Italy. Emphasis is placed on disseminating information to end-users, specifically practical operators, and on the agreed-upon tools and approaches to distribute information and trigger alerts. More specifically, we describe 5 LEWS aimed at predicting the possible initiation of rainfall-induced landslides. Three of these systems operate at a regional scale (two administrative regions and a single railway segment in the Apennine region), while the other two cover the entire national territory, with the objective of assessing the potential initiation of rainfall-induced landslides and their potential impact on the national railway network. These systems differ in the type and quantity of data used in the forecasting chain, the extent of monitored areas, product resolutions, interfaces, and communication systems.The intent is to share our experiences, challenges, and solutions, thereby fostering advancements and refinements in landslide early warning systems at both national and international levels.
New insights into alien aquatic plants ecology - response model to an elevated water temperatures
Authors: Draga Mateusz , Gąbka Maciej , Szczęśniak Ewa , Rosadziński Stanisław , Lisek Daniel , Bryl Łukasz
Published: March 2024

Freshwater ecosystems are widely recognized as a significant global biodiversity hotspot. Unfortunately, they are also highly vulnerable to the expansion of invasive aquatic species, whose spread is considered among the top threats to these ecosystems. Especially problematic are alien aquatic plants species whose rapid growth often disrupts local communities and may even alter physicochemical conditions of a given freshwater ecosystem. Since most of invasive aquatic plants are native to tropical regions of the world, their occurrence in some Central and Eastern Europe countries was, until relatively recently limited by cold winters typical for this part of the continent. However, in the last two decades, we have observed a sharp increase in these species abundances in this part of Europe, which can be linked to the warmer winters resulting from the ongoing climate change. In our study, we examine the effects of temperature changes resulting from global warming on the development and occurrence of several aquatic alien plant species. Our analysis is based on our unique data base that contains extensive information about all currently known alien vascular aquatic plant species present in Poland as well as their precise location. This data is notable for being the first such database summarizing the current status of aquatic plant invasions for this country. Based on it, as well as temperature data from the last several years, we created generalized additive models (GAM) for temperature response for each of 15 aquatic alien plant species known for Poland. Our results show a strong relationship between rising temperatures and the spread of certain species, i.e. Azolla filiculoides. Furthermore, spread of such species as Elodea nuttallii and Lemna turionifera in Poland does not rely strongly on temperature. Presence of some species was found to be highly dependent on highly thermally altered or thermally contaminated waters, i.e. Vallisneria spiralis, Hygrophila polysperma, and  thus their occurrence is still limited only to such locations. Our results confirm the major role of elevated temperatures and thermal modification of waters in the distribution of alien aquatic plants.
The fast response of precipitation to historical black and sulfate aerosols in the GFDL ESM4 climate model
Authors: zhang Yanda , Knutson Tom , Shevliakova Elena , Westervelt Daniel
Published: March 2024

Aerosol effects on precipitation are crucial factors in climate change, yet they remain poorly understood, representing a large source of uncertainty in climate models. In the GFDL Earth System Model 4 (ESM4), simulated historical century-scale trends of global land precipitation demonstrate significant dry biases compared to observations, even with observed historical variations of sea surface temperature and sea ice concentrations (LongAMIP simulation). The biases manifest as overestimated decreasing precipitation trends over tropical-subtropical land and underestimated increases in higher latitudes. In this study, we investigate the “fast response” of precipitation to historical anthropogenic aerosol emissions and its contributions to the model trend biases, by conducting idealized ESM4 LongAMIP experiments with emissions of either black carbon (BC) sulfate (SO4) aerosol precursors set to near-pre-industrial levels (1850). Aerosol direct radiative effects emerge as critical drivers of excessive precipitation declines in some regions: (1) over East Asia, the negative SO4 effect and positive BC effect contribute to changes in historical precipitation and the associated model responses lead to the simulation bias. (2) For regions of Africa, the negative fast response to SO4 partially contributes to the overestimated precipitation decline. (3) Over west-central North America, the negative fast response to BC in the model contributes toward underestimating a modest observed increasing precipitation trend. However, over eastern North America and Northwest Eurasia, the fast responses of precipitation to aerosols cannot account for the opposite direction of model bias, indicating the dominant influence of other factors.
Applicability of cloud radar observations for an intra-event analysis of runoff on a steep vineyard
Authors: Nomokonova Tatiana , Myagkov Alexander , Biddoccu Marcella , Capello Giorgio , Maschwitz Gerrit , Canone Davide , Ferraris Stefano
Published: March 2024

Studying runoff on steep vineyards is an important topic in the agricultural science. Steep vineyards are especially susceptible to soil erosion due to the force of water runoff. Runoff can also carry sediment, pesticides, and fertilizers thus affecting nutrient efficiency and water quality. Understanding of how runoff depends on properties of rain and state of soil can help to improve soil management practices.There is a number of studies investigating how runoff depends on properties of rain and soil. Typically, the amount of runoff is related to maximum rain intensity, total precipitation, soil water content, etc. Based on a large number of runoff events, often collected over multiple years of observations, the runoff can be represented as a linear regression of the abovementioned variables. However, these linear regressions are highly variable from time period to time period and also among different sites. In order to better understand possible reasons of such variability, a more detailed analysis of single events is required.   In this study we make an attempt to characterize the water budget within a single rain event. From summer 2023 we have run a measurement campaign at an operational site in the Alto Monferrato vine-growing area (Piedmont, NW Italy). For the campaign the site, which is already well equipped with state-of-the art soil and runoff sampling tools, was complemented by a polarimetric cloud radar. The cloud radar can obtain range-resolved profiles of drop-size distribution with high spatial and temporal resolution. The radar observations can be used to characterize rain and to check how variable rain properties are over the field. The main advantages of cloud radars over conventional in-situ rain sampling devices are much larger sampling volume and range profiling of rain properties.During the summer and autumn seasons we have already collected more than 10 runoff events with different duration and intensity. The collected dataset allows us to relate runoff to rain and soil properties on intra-event scale. The rain intensity is characterized based on cloud radar observations. The water content is measured by moisture sensors located at three different depth levels. Finally, the amount of runoff is measured using 12 L tipping buckets. The site is split into plots with different soil management in the inter-row. This makes it possible to also investigate how different cover affects the water budget.
Quantifying mantle mixing through configurational Entropy
Authors: Thieulot Cedric , van der Wiel Erik , van Hinsbergen Douwe
Published: March 2024

Geodynamic models of mantle convection provide a powerful tool to obtain insights into the structure and composition of the Earth’s mantle that resulted from a long history of differentiating and mixing. Comparing such models with geophysical and geochemical observations is challenging as these datasets often sample entirely different temporal and spatial scales. Here, we explore the use of configurational entropy, based on tracer and compositional distribution on a global and local scale. We show means to calculate configurational entropy in a 2D annulus and find that these calculations may be used to quantitatively compare long-term geodynamic models with each other. The entropy may be used to analyze, with a single measure, the mixed state of the mantle as a whole and may also be useful to validate numerical models against local anomalies in the mantle that may be inferred from seismological or geochemical observations.
Can convection permitting forecasts solve the tropical African precipitation forecasting problem?
Authors: Rein Felix , Fink Andreas H. , Gneiting Tilmann , Peyrille Philippe , Warner James , Knippertz Peter
Published: March 2024

Forecasting precipitation over Africa, the largest landmass in the tropics, has been a long standing problem. The unique conditions of the West African monsoon result in large and long lasting mesoscale convective systems. Global numerical weather prediction (NWP) models have gridsizes in the 10s of kilometers, particular when run in ensemble mode, leaving convection to be parameterized. This often results in precipitation being forecast on too large scales, in the wrong places, and with too weak intensity, ultimately leading to little to no skill in tropical Africa.It has been argued that convection permitting (CP) NWP forecasts would cure some of the problems described above but those have only recently become feasible in an operational setting, although ensembles are still deemed to be too expensive. Here, we systematically compare regional deterministic CP and global ensemble forecasts in the region over multiple rainy seasons for the first time. We analyze CP forecasts from AROME and Met Office Tropical African Model, and seven global ensemble forecasts from the TIGGE archive, both individually and as a multi-model ensemble. In order to create an uncertainty estimate, we create neighborhood ensembles from CP forecasts at surrounding grid points, which allows for a fair comparison to the ensembles and a probabilistic climatology. Considering both precipitation occurrence and amount, we use the Brier score (BS) and the continuous ranked probability score (CRPS), along with their decompositions in discrimination, miscalibration and uncertainty, for evaluation.Using neighborhood methods, deterministic forecasts are turned into probabilistic forecasts, allowing a fair comparison with ensembles. All numerical forecasts benefit from Neighborhoods, improving their BS and CRPS in terms of both miscalibration and discrimination. We find all individual forecasts to have skill over most of tropical Africa, with some ensemble models lacking skill in some regions and the multi model showing the most overall skill. The CP forecasts TAM and AROME outperform non-CP forecasts mainly in the region of the little dry Season and the Soud. However, large areas of low skill in terms of CRPS remain and even with high resolution, numerical models still struggle to predict precipitation in tropical Africa. 
A Novel Process Model of Ocean-Sea-Ice Interaction Using CESM
Authors: Hall Paul , Horvat Christopher , Fox-Kemper Baylor , Brenner Samuel , Altuntas Alper
Published: March 2024

We report on the development of a novel process model created to study ocean-sea ice interaction and the dynamics of the upper ocean in the marginal ice zone (MIZ), built using the Community Earth System Model (CESM). Our model uses the MOM6 ocean model and CICE6 sea-ice model as active components within CESM, on a custom ~50km x ~50km grid with a horizontal resolution of ~50m, extending to a depth of 75m (30 vertical layers). The model allows for either reflecting or zonally re-entrant boundary configurations. Atmospheric forcing is imposed through a simplified data atmosphere component that provides constant forcing over the model domain. Results from several simple scenarios are presented and compared to results obtained using the MITgcm.By working within CESM, we are able to leverage CESM’s existing infrastructure and capabilities, including the use of the Community Mediator for Earth Prediction Systems (CMEPS) for coupling between active components. Furthermore, additional model components that are already available within CESM (e.g., waves, atmosphere) can be incorporated into the process model in a straightforward way. Future work will include incorporation of a modified sea-ice component that allows tracking of individual floes utilizing a discrete element method approach.
Generation of long-term ground fog time series using harmonized time series cross-calibrating two Meteosat generations
Authors: Gaurav Sheetabh , Thies Boris , Egli Sebastian , Bendix Jörg
Published: March 2024

Fog, a meteorological phenomenon resulting in horizontal visibility of less than 1000 meters, has significant socio-economic and environmental consequences. Current long-term research on the fog occurrence based on station data have indicated that the frequency of fog has decreased over Europe since the 1960s. However, due to a limited number of ground-based observations, primarily in low-altitude areas, there is insufficient evidence to support the hypothesis that fog is decreasing across Europe. In order to scientifically investigate different factors which might be responsible in influencing fog formation over the years over space and time, there is a need of long term consistent satellite data time series to analyze the fog distribution. In this study, first a machine learning based methodology has been developed and implemented to harmonize the two generation Meteosat datasets, i.e. Meteosat First Generation (MFG) and Meteosat Second Generation (MSG) to generate a long-term consisent dataset (1991-2020) which can be further used to classify fog over the European domain (WMO region VI). For this, a Random Forest (RF) based model is trained during the overlap period (2004-2006) of MFG and MSG datasets, to synthesize MFG data from MSG data to generate a consistent MFG time series. The results of this model indicates a good match of synthesized MFG datasets with the original MFG datasets during the overlap period with mean absolute error (MAE) of 0.7 K for the WV model and 1.6 K for the IR model and out-of-bag (OOB) R2 score of 0.98 for both models. In the next stage, this harmonized dataset is currently being investigated along with the CM-SAF MSG based cloud mask dataset to generate a homogeneous cloud mask over the domain using a machine learning based eXtreme Gradient Boosting (XGBoost) classifier model. The current version of the cloud mask is able to predict high & mid level clouds for both day and night time with high accuracy. In case of fog and low stratus (FLS) clouds, the model exhibits excellent performance during day time but encounters some difficulty in detecting in certain FLS patches during night time. This resultant cloud mask can subsequently be employed to classify fog occurrences by integrating harmonized MFG WV and IR channels with cloud base altitude (CBA) as well as visibility data obtained from Meteorological Aviation Routine Weather Reports (METAR) and synoptic weather observations (SYNOP) within a machine learning-based model. In this context, we present the current ongoing progress and the preliminary results in generating a 30 years fog climatology (1991-2020) for Europe with a temporal resolution of 30 minutes using this dataset.
Km-scale climate simulations with IFS-FESOM
Authors: Beyer Sebastian , Sidorenko Dmitry , Ghosh Rohit , John Amal , Rackow Thomas , Streffing Jan , Cheedela Suvarchal Kumar , Niraula Bimochan , Koldunov Nikolay , Jung Thomas
Published: March 2024

Within the EU’s Destination Earth (DestinE) initiative we are developing a digital climate twin with km-scale resolution. This enables us to resolve physical processes that, so far, have only been represented by approximations. This core model setup (called digital twin engine)  is able to run multidecadal simulations for historic periods as well as different future scenarios in unprecedented resolution which will be used by decision makers.In phase one of DestinE, our goal is to run a control simulation (under 1950 pre industrial conditions), a historic simulation from 1990 to 2020 and finally, projection simulations from 2020 to 2040. The control run will be performed with a global atmospheric resolution of 9km, while the projection simulations use 4km. The ocean component uses the unstructured NG5 mesh, which means an approximate resolution of 5km.In this work we present the latest iteration of the IFS-FESOM model, the Integrated Forecasting System coupled to the Finite volumE Sea Ice-Ocean Model FESOM2. We explain its components and recent improvements, including  the integration of ECMWF’s IO-server and post processing toolkit multio into the FESOM2 component and the introduction of a novel runoff mapper. Preliminary results from our kilometre-scale simulations are shown and compared to preindustrial conditions, with the primary objective to quantify effects of a ~1K warming world.
ESA/NASA Quality Assurance Framework for Earth Observation Products
Authors: Hunt Samuel , Albinet Clément , Nickeson Jaime , Osmanoglu Batuhan , Hall Alfreda , Lin Guoqing , De Laurentiis Leonardo , Goryl Philippe , Policelli Frederick , Ostrenga Dana , Fox Nigel
Published: March 2024

Across the broad potential user base for Earth Observation (EO) data, confidence in the quality of the available products is vital, particularly for users requiring quantitative measured outputs they can rely on. Particularly as the commercial EO sector rapidly expands, however, it is an increasing challenge for the user community to discern between the wide variety of product offerings in a reliable manner, especially in terms of product quality. In response to this ESA and NASA, through their Joint Program Planning Group (JPPG) Subgroup, have developed a common EO product Quality Assurance (QA) Framework to provide comprehensive assessments of product quality. The evaluation is primarily aimed at verifying that the data has achieved its claimed performance levels, and, reviews the extent to which the products have been prepared following community best practice in a manner that is “fit for purpose”. A Cal/Val maturity matrix provides a high-level colour-coded a simple summary of the quality assessment results for users. The matrix contains a column for each section of analysis (e.g., metrology), and cells for each subsection of analysis (e.g., sensor calibration). Subsection grades are indicated by the colour of the respective grid cell, which are defined in the key. Both ESA and NASA have on-going activities supporting the procurement of commercial EO data that make use of the joint QA Framework – to ensure decisions on data acquisition are made with confidence. On the ESA side, the Earthnet Data Assessment Project (EDAP) project performs data assessments on EO missions in optical, atmospheric and SAR domains. Similarly, the NASA Earth Science Division (ESD) Commercial Smallsat Data Acquisition (CSDA) Program, completed a pilot study in 2020, and has since entered sustainment use phase for some of the commercial data sets. In this presentation the joint ESA/NASA QA Framework is described, with some examples of its application to commercial EO products.
Ion cyclotron waves at Io: Pick-up rate and outgassing
Authors: Volwerk Martin , Bagenal Fran , Dols Vincent , Kivelson Margaret , Khurana Krishan , Lammer Helmut , Schmid Daniel , Simon Wedlund Cyril , Jia XianZhe
Published: March 2024

With its extended mission, JUNO is getting close to Io and performs moon flybys. It is therefore time to (re)analyse the already available magnetometer data from close flybys of Io by Galileo. Earlier studies of the J0 flyby showed the presence of ion cyclotron waves generated by the pick-up of SO2+ and determined the density of the picked-up ions. In this presentation we study all five Io flybys by Galileo and investigate the presence of ion cyclotron waves for three different species. SO2+, SO+ and S+. Through Fourier analysis and calculation of the cross-spectral matrix and strong criteria on power, polarization and ellipticity, we determine intervals of significant wave activity. Under the assumption of bi-spherical scattering of the pick-up ions in the velocity ring-distribution, an estimation of the pick-up ion density can be obtained. Through an assumption of the ionization frequency, this can be converted into a neutral density to obtain a value of the total neutral gas emitted per second and compare it to the usually assumed 1000 kg/s. Naturally, the five flybys will also give information about differences generated by local time, longitude and latitude.
Intrinsic permeability of porous systems: models and microfludiic experiments for heterogeneous structures
Authors: Jiao Wenqiao , Scheidweiler David , Delouche Nolwenn , Guadagnini Alberto , de Anna Pietro
Published: March 2024

Understanding the relationship between flow (Q) and pressure drop (ΔP) for porous media is a long-standing challenge affecting a wide variety of environmental, societal and industrial issues, from soil remediation to enhanced oil recovery. While for homogeneous media such dependence is well represented by the Kozeny-Carman formula,  the fundamental nature of such a relationship (Q vs ΔP) within heterogeneous systems, characterized by a broad range of pore sizes, is still not understood. We design a set of controlled and complex porous structures that we use to conduct microfluidics experiments to measure their intrinsic permeability. We synthesize the results upon deriving an analytical formulation relating the overall intrinsic permeability and key features of the porous structure. We propose to embed the spatial variability of pore sizes into the medium permeability by upscaling the flow through each pore, via the Hagen Poiseuille Law. Our prediction fits well the collected data, highlighting the role played by the micro-structure on the overall medium permeability. Furthermore, beside the theoretical understanding of this important relationship, we also extend our set-up to novel experiments focusing on the paradigmatic case study of biofilm growth that affects the system permeability by obstructing the pore spaces.
Basaltic magma dynamics during the 2021-2023 eruptions at Reykjanes Peninsula, Iceland, constrained by Sr, Nd and Th isotope ratios
Authors: Sigmarsson Olgeir
Published: March 2024

The composition of MgO-rich basalt produced during the six-months long 2021 eruption at Fagradalsfjall, Reykjanes Peninsula, varied from those with low K2O/TiO2 and incompatible element contents to basalt enriched in incompatible elements with high K2O/TiO2 over a timespan of a month, explained by binary mixing of different mantle melts (Halldórsson et al., 2022). For the rest of the eruption, the basalt composition varied in a periodic manner as illustrated by long-lived radiogenic isotope ratios. For example, the periodicity of 87Sr/86Sr from early May to middle of September 2021 was 52 days, likely representing the time elapsed from the final melt mixing at depth (the moment of acquiring the measured isotope composition) until eruption at surface. Preliminary results on Th isotope ratios in the 2021 Fagradalshraun yield relatively high Th isotope ratios [(230Th/232Th) = 1.30] in the first lava emitted (the low K2O/TiO2 basalt) relative to basalt erupted at the end of the eruption [(230Th/232Th) = 1.18]. While this observation could be explained by slower mantle melting, excellent correlation between Th and Nd isotope ratios confirms the importance of binary mixing of melts from a depleted mantle source (with high Th and Nd, and low Sr isotope ratios) with melt(s) from enriched mantle lithology (having lower Th and Nd, and higher Sr isotope ratios) before magma ascent and eruption. Consequently, mantle heterogeneity, melt aggregations and mixing dominate the composition of the erupted basalt, rather than the duration of mantle melting. Correlation between Sr isotope ratios and time-averaged discharge rate indicate mantle source fertility control on the discharge rate during the 2021 eruption.  Both the 2022 and the summer 2023 eruptions started with a stronger discharge rate than that of 2021 and produced basalt of similar composition as that emitted in September 2021, interpreted as a result of an establishment of crustal magma accumulation zone since at the end of the 2021 eruption. Moreover, whether the exhaustion of the low K2O/TiO2 and 87Sr/86Sr magma reservoir led to the end of the 2021 eruption remains to be explored.
What can we expect from angular velocity sensing for future gravity missions?
Authors: Yan Yihao , Müller Vitali , Heinzel Gerhard , Wang Changqing , Zhu Zitong
Published: March 2024

The GRACE-like gravity satellites are designed to provide accurate measurements of the global time-varying gravity field, allowing to monitor the changes in the distribution of the Earth's mass caused, for example, by climate change. The gravity information is encoded in the line-of-sight vector, which is given by the position difference between the satellites. The key observable of GRACE and GRACE follow-on is the change in length of the LOS vector, measured by dedicated ranging instruments (K-band ranging system (KBR) or laser ranging interferometer (LRI)). However, the orientation of the LOS vector is measured with some precision using GNSS/GPS, which limits the accuracy of the gravity field maps. To overcome this problem, we propose the use of a dedicated angular velocity sensing (AVS) system that tracks the changes in the orientation of the line of sight with respect to the inertial frame. The angular velocity vector of the LOS has two independent components, yaw and pitch, which we introduce as additional observations in the gravity field recovery process. We firstly show how the AVS and range observables can be used to reconstruct the 3-dimensional differential acceleration vector. Then we find that the inversion results with AVS and regular ranging can mitigate the effect of AOD errors and significantly improve the accuracy of the gravity fields if more accurate AVS observations are available than currently provided by GNSS/GPS orbits. One potential way to achieve more accurate AVS observations is to use differential wavefront sensing (DWS) to accurately measure the orientation of the accelerometer test masses with respect to the platform, giving lower noise than the conventional star cameras, and combine these measurements with the DWS measurements from the inter-satellite laser interferometer to obtain the orientation of the LOS with respect to the inertial frame. With a DWS noise level of 0.1 nrad/√Hz, a single pair of GRACE satellites can achieve the same accuracy as a four-satellite Bender configuration. This study provides a promising alternative to the development of multiple satellite pairs to improve the accuracy of gravity missions.
Detecting Trends In Hydrological Extremes And Non-Stationary Extreme Value Analysis Of Flood Data In Kwazulu-Natal, South Africa
Authors: Mukansi Demian Vusimusi , Smithers Jeff , Johnson Katelyn , Kjeldsen Thomas , Mutema Macdex
Published: March 2024

In this study, the annual maximum streamflow from 14 stations in KwaZulu-Natal, along the East Coast of South Africa, were analysed. Trends were investigated using the non-parametric Mann-Kendall test and the Sen Slope tests, and the results indicate that the annual maximum streamflow has been decreasing in magnitude at 78 % of stations. Extreme value analysis was performed using both stationary and non-stationary models using time and rainfall as covariates. The results show that the stationary models are superior to non-stationary models at most stations with time as a covariate. Where possible, streamflow stations were linked with rainfall stations to determine the impact of rainfall on annual maximum streamflow. The results indicate that the non-stationary model incorporating observed rainfall as a covariate performed better than the stationary and non-stationary models with only time as a covariate. Therefore, incorporating rainfall in design flood estimation should be considered to account for non-stationary trends and to mitigate the risk of failure of hydraulic structures. Regional magnification factors to account for non-stationarity were not investigated further in this study as the majority of the stations showed a negative trend, which means the application of a regional magnification factor will result in a reduction of the magnitude of the estimated design floods.
Integration of historical glacier images into the Euro-Climhist database
Authors: Rohr Christian , Nussbaumer Samuel U. , Walker Céline , Haller Corina , Widmer Tamara T. , Fries Matthias , Würsch Lukas , Zumbühl Heinz
Published: March 2024

Glaciers are excellent climate indicators, and the worldwide glacier retreat serves as a warning signal for the current climate change with its dramatic effects on humans and the environment. Visualizing glacier change by means of images can reach a broad public. Historical glacier images, especially from the so-called Little Ice Age (LIA, approx. AD 1300 to 1850 in the European Alps), show the earlier glacier fluctuations in a particularly impressive way and give us a unique insight into the climatic events of that time. These findings are in turn the key to understand current and possible future climate changes.The long-term research project "Euro-Climhist" is one of the first projects of its kind worldwide to extract historical documentary data on climate and weather from a wide variety of source types, evaluate the data accordingly, and make it generally accessible in an online database (https://www.euroclimhist.unibe.ch). Until now, the Euro-Climhist database consisted mainly of written sources and measurement data. Within this project, the Euro-Climhist database was conceptually extended to include and secure glacier images in the long term, and to make them accessible to researchers and to the public. Around 500 glacier images were specially prepared for the database and provided with the corresponding metadata, i.e., the name of the artist, the original descriptions as well as supplementary descriptions from the literature, the dating of the images, and the image type. In particular, the assignment to one of five image types - drawing, oil painting, print, photograph, or map - allows conclusions to be drawn about the accuracy of the glacier extents depicted.Besides written evidence, historical pictorial representations of glaciers allow us to reconstruct glacier extents in the Alps from the early 17th century onwards. Satisfactory quantities of historical material are only available for those glaciers that achieved the necessary degree of fame early on to attract travellers, scientists, and artists. Pictorial representations in painting and graphic arts date back to the early 17th century, but only appear in large numbers with the emerging popularity of Alpine travel during the 18th century. Photographs are available from the end of the 1840s.
Estimating methane sources and sinks by assimilating satellite data in a global atmospheric inverse system.
Authors: Montenegro Nicole , Saunois Marielle , Berchet Antoine , Martinez Adrien , Bousquet Philippe , Pison Isabelle
Published: March 2024

Methane (CH4) is the second most important greenhouse gas, contributing to approximately 30% of the additional greenhouse effect since 1750. Its varied sources and relatively short lifetime in the atmosphere (~9 years) offer interesting mitigation opportunities. To develop practical strategies for mitigating climate change, precise quantification of methane fluxes and a better understanding of its spatial distribution and biogeochemical cycling are imperative. The observations currently used to infer methane sources and sinks face limitations affecting calculation accuracy. Surface stations measuring CH4 are sparse and notably absent in major emitting regions. In contrast, satellite-derived data, while providing broader coverage, present systematic errors and estimate atmospheric composition with an accuracy range of 1-10%. Additionally, passive satellite shortwave infrared (SWIR) measurements exhibit higher sensitivity near surface emission sources but are less effective in high latitude regions. Conversely, passive satellite thermal infrared (TIR) measurements have a higher sensitivity between the free troposphere and the stratosphere.Current worksare currently being developed to integrate TIR and SWIR to obtain consolidated CH4 information on the vertical atmospheric profile. This studyaims on improving methane flux estimates using the top-down approach, which integrates observations, flux priors, and an atmospheric chemical transport model utilizing Bayesian methodology. This will be perfomed on the inversion system developed at the LSCE (Community Inversion Framework – CIF) using the global transport model LMDz. We analyze the information provided by different observing systems (TIR, SWIR and surface network) at the global scale and for a period between June 2018 and June 2020. In a first step, the sensitivity of the fluxes to the observations is estimated. In a second step, Observing System Simulation Experiments are performed to evaluate the performance of the different observations system to retrieve the target fluxes. Considering both steps, observing systems are chosen to provide the best information in terms of sensitivity and spatial representation (vertical and horizontal).