bluuebunny/crossref_metadata_2025 huggingface dataset:
European contribution to the OneArgo array
Authors: Gourcuff Claire , Berry Alan , Carse Fiona , Kassis Dimitris , Klein Birgit , Mork Kjell Arne , Notarstefano Giulio , Slabakova Violeta , Stedmon Colin , Sterl Andreas , Thierry Virginie , Tuomi Laura , Velez Pedro , Walczowski Waldemar , Siiriä Simo-Matti
Published: March 2024

The Argo Programme is a major component of both the Global Ocean Observing System (GOOS) and the Global Climate Observing System (GCOS), providing near-real time data for ocean and atmospheric services and high-quality data for climate research. Although originally designed to provide temperature and salinity profiles in the upper 2 km of the ice-free ocean, the array has been expanded into seasonal ice zones. In addition, regional pilot programmes have demonstrated that some Argo floats can now measure biogeochemical parameters to address oceanic uptake of carbon, acidification, and deoxygenation (BioGeoChemical, BGC-Argo) and some floats are also able to make measurements throughout the water column down to 6000 m depth (Deep-Argo). These new BGC-Argo and Deep-Argo Missions, together with the initial Core-Argo Mission form the new global, full-depth and multidisciplinary OneArgo programme (Roemmich et al. 2019).
Euro-Argo aims at maintaining ¼ of the global OneArgo array, with a regional perspective focusing on European marginal seas (Mediterranean, Black and Baltic seas) and the European part of the Arctic seas.
The Euro-Argo strategy focuses on providing sustained high quality oceanic data to the scientific community for better understanding of the role of the Ocean in the Earth’s climate. Addressing issues of climate change along with expanding floats’ capabilities and coverage are at the centre of the Euro-Argo strategy. Another domain of grand challenges is related to the health of the oceanic ecosystem and its impacts on society. The recent technological advances in biogeochemical instrumentation on Argo floats have greatly improved the ability to address ecosystem monitoring, and gather data in the European marine areas to support climate and biodiversity policies set up by the European Union. Moreover, Argo is a major source of information for operational centres such as the Copernicus Marine and Climate Services and the European Centre for Medium-Range Weather Forecasts (ECMWF) in Europe, for the provision of ocean and weather forecasts and seasonal predictions. Euro-Argo supports the enhancement of monitoring and observing systems at regional scales for model-assimilation and model-validation purposes. In particular, the extensions of Argo into the deep ocean and ecosystem parameters offer new possibilities and will help to constrain and improve the models and resulting products.
Within this context, Euro-Argo is currently revising its deployment and coverage strategy for the next decade, taking into consideration specific European needs in terms of in situ ocean observations, while contributing to the global OneArgo new ambitious design.
We will present this strategy and provide some highlights on the challenges for the years to come.
Comparison of different stratospheric parameters from reanalysis and satellite data
Authors: de la Torre Laura , Añel Juan A. , Šácha Petr , Kuchař Aleš , García Rolando , Mlynczak Martin G.
Published: March 2024

In this study we compare various stratospheric parameters obtained from reanalysis and satellite data. The data from ERA5.1, MERRA2, JRA55, and JRA3Q reanalysis, as well as from the MLS and SABER satellite instruments are used to assess the agreement between reanalysis and satellite data in the stratospheric layer. In particular, the geopotential height of the tropopause and stratopause, as well as the stratospheric thickness, are computed and compared. The results show that the most significant discrepancies are observed in the tropics (30ºS to 30ºN) and the global mean, where negative correlations with satellite data are found. The correlations in the southern hemisphere extratropics are lower than those in the northern hemisphere extratropics. Moreover, the stratospheric thickness, a priori expected to be well-correlated with the stratospheric temperature, not always behaves this way.
The 2021 and 2023 Vienna Basin seismic sequences: Insights from earthquake relocation and moment tensor inversion
Authors: Papí Isaba María del Puy , Buforn Elisa , Mattesini Maurizio , Petersen Gesa , Cesca Simone , Hausmann Helmut , Lenhardt Wolfgang
Published: March 2024

Three peculiar seismic sequences occurred between March and May 2021 near Breitenau and Gloggnitz, about 50 km from Vienna, Austria. The seismic sequences’ mainshock epicentres are less than 15 km apart. In March 2023, seismic activity resumed in the Gloggnitz area and continued to be relatively high in comparison with the average background seismicity of the region.The first of these sequences started on March 30th, 2021, with the occurrence of an ML4.6 and h = 9 km earthquake close to Breitenau. A period of increased seismic activity lasted ~2 weeks, before decreasing to the background seismicity rate by mid-April. On April 19th, 2021, an earthquake with similar magnitude and depth (ML4.4 and 9 km) occurred only 1 km northeast of the previous ML4.6. The following seismic sequence lasted until the end of May 2021. The third seismic sequence started on April 20th, 2021, ~15 km SW of the Breiteau sequences, with a shallow (h = 5 km) ML3.5 earthquake followed by the mainshock (ML3.8 and h = 5 km) on April 23rd, 2021 (ML3.8 and h = 5 km). Seismicity decayed to background rates by early May. On March 30th, 2023, the seismic activity resumed in the Gloggnitz area with a mainshock (ML4.2 and h = 10 km). Its epicentre was located between the 2021 Gloggnitz foreshock (ML3.5) and the mainshock (ML3.8). Compared to the 2021 Gloggnitz sequence, there was no significant surge in seismic activity following the ML4.2 event, and the seismicity levels remained moderately high, compared to the typical seismic activity observed in the year 2021, until the beginning of October.In this study, we relocated all events using a non-linear location method and used a probabilistic full waveform inversion tool to derive full moment tensor solutions for the largest earthquakes of the sequences (ML4.6, ML4.4, ML4.2 and ML3.8). These neighbouring sequences, which cluster spatially along a narrow seismicity band, but show different focal mechanisms and different temporal evolutions, shed light on the segmentation of local seismogenic processes and complex fault system along the seismogenic lineament.
Adaptive capacity in the water sector under socio-economic and climate uncertainty.
Authors: Vinca Adriano , Andrijevic Marina , Byers Edward
Published: March 2024

Under the impelling challenges posed by climate change, population growth, and evolving socio-economic landscapes, the ability of water systems to adapt to changing conditions is critical for ensuring resilience and sustainable resource management. As various regions face escalating water scarcity and more intense occurrences of droughts and floods, many of these areas also deal with underdeveloped infrastructure, a lack of access to sanitation services and essential water resources for both population and agricultural activities.
When rainfall patterns change and groundwater is at risk of exploitation, water-saving techniques and alternative water sources such as desalination and water recycling need to be made available, which implies higher costs than conventional water sources.
Using different datasets on technology adoption and country survey data, we assess the historical development of potential adaptation technologies (desalination and wastewater treatment), as well as trends in water infrastructure providing access and sanitation services. We then study the relation of these variables to socio-economic factors (e.g. population, GDP, governance) and climate variables (temperature increase, water stress, flood intensity). We use regression models to understand the future capacity to develop and adapt under different socio-economic futures (identified with the Shared Socio-economic Pathways, SSPs) and climate scenarios, defined by levels of warming.
Preliminary results show a strong linkage between water access and sanitation indicators with GDP and inequality, while governance structure seems to play a significant role in the deployment of desalination technologies.
Comparative analyses of different technologies will help modelling communities explore the effectiveness of different adaptive strategies and inform policy decisions on the most suitable and challenging adaptation options in the water sector.
Carbon and nitrogen stable isotopes across the last deglaciation: perspectives from snow petrel stomach oil deposits
Authors: Damm-Johnsen Thale , Bentley Michael J. , Gröcke Darren R. , Hodgson Dominic , McClymont Erin L.
Published: March 2024

Evidence from both marine and ice cores strongly indicates that surface ocean processes influencing air-sea gas exchange of the Southern Ocean played a crucial role in the transition from a glacial to interglacial climate state. However, few archives have been able to reconstruct how high latitude surface ocean processes affected the biogeochemical changes occurring in nutrient utilization, primary productivity, and their effects on carbon sequestering in ecosystems. An opportunity to explore these processes is provided by accumulated snow petrel (Pagodroma nivea) stomach oil deposits, defensively regurgitated by snow petrels at their nest sites. These deposits provide a record of biogeochemical processes in the austral summer, at a high trophic level and integrated over a relatively wide area defined by snow petrel foraging range. Here, we present a joint carbon and nitrogen stable isotope record from stomach oil deposits from the Lake Untersee nunataks in Dronning Maud Land (DML) integrating data from a coastal area of 65-70°S. Our results show a 3‰ offset in δ13C and 4‰ offset in δ15N between LGM and Holocene, indicating that the coastal high latitudes underwent large changes over the deglaciation. The δ15N depletion into the Holocene shows strong similarity to changes occurring in nutrient utilization along the margin of the polar front, indicating that the Southern Ocean high latitudes were not an isolated oasis during the LGM but biogeochemically connected to the surface ocean beyond the summer sea-ice margin. In addition, the presence of stomach oil deposits indicates that open water was present in summer along the coast of DML over both the LGM and Holocene. Such highly productive, open water areas were potentially an important factor in the air-sea gas exchange contributing to the deglacial atmospheric CO2 -rise.
Collect and analyze data to make informed choices
Authors: Rizzi Elena
Published: March 2024

Good data collection is among the first phases of a correct scientific method. During the 2023/2024 school year, in two classes of the "Ilaria Alpi" secondary school in Chiavari (Genoa, Italy), we collected data on the consumption of water, food, energy and on the methods of travel of the pupils and their families. The objective was to understand the extent and type of consumption, with the aim of proposing positive daily actions to reduce consumption.We created questionnaires and collected data. We then represented the data with different graphical methods and discussed them. We then moved on to the discussion and the proposal of actions, which we disseminated within our school and, in the case of mobility, to the administrators of our Municipality.
Assessment of the Topographic Wetness Index in Permafrost landscapes 
Authors: Widhalm Barbara , Bartsch Annett , Bergstedt Helena , von Baeckmann Clemens , Strozzi Tazio
Published: March 2024

Arctic permafrost regions are subject to rapid changes due to climate warming affecting hydrology, topography and ecology. Soil wetness is of great importance in these regions facilitating for example upscaling of carbon fluxes. In this study we therefore investigate the Topographic Wetness Index (TWI) as often used in land surface modelling, focusing on study regions in the Siberian and Canadian Arctic. We analyse the influence of the used Digital Elevation Model (DEM) by comparing results of the openly available ArcticDEM (2m resolution) and Copernicus DEM (30m resolution). Results are being validated against near-surface soil moisture in-situ measurements. Further comparisons are being made to other wetness indices such as the Tasselled Cap Wetness index or the Normalized Differential Moisture Index derived from Landsat 8. The relationship to InSAR derived surface displacements as an indicator of soil wetness is explored, as well as additional parameters such as the Topographic Position Index and correlations to other moisture indicators including land cover products.
Particle-laden gravity currents: the lock-release slumping regime at the laboratory scale
Authors: Lacaze Laurent , Gadal Cyril , Schneider Jean , Bonamy Cyrille , Chauchat Julien , Dossmann Yvan , Kiesgen de Richter Sébastien , Mercier Matthieu , Naaim-Bouvet Florence , Rastello Marie
Published: March 2024

Particle-laden gravity currents (PLGCs) are driven by the mass difference between a heavy fluid-particle mixture and a lighter ambient liquid. They often occur in natural and industrial situations, among which a typical situation is the release of a finite volume. Here, we focus on such `dam-break' situations, which are studied using lock-release devices at the laboratory scale. The objective of the presententation is to provide a description at the macroscopic scale of the early moments of the flow, namely the slumping regime, with respect to the relevant dimensionless parameters. For this, we combine a total of 288 runs from three different lock-release devices and from two-fluids numerical simulations, which allow us to cover a large range of particle types (size and density), volume fractions, bottom slopes and geometries. By tracking the front propagation through time, we extract the dimensionless slumping velocity Fr and dimensionless characteristic slumping duration τ, on which we base our description. Our results show that the slumping velocity increases with the bottom slope, but decreases with the particle volume fraction when the latter exceeds a critical value. However, it remains independent of particle settling processes, which on the other hand affects the slumping duration. Hence, above a critical threshold, τ decreases as the ratio between the settling velocity and characteristic current velocity increases. For all these regimes, we derive scalings and energetic balances that reproduce the observed trends. The latter comparison confirms the role of initial energy transfer from the initial state towards the slumping phase on the resulting dynamics. This initial process and its characterisation remain crucial to prescribe relevant initial conditions for large-scale predictive modelling.
Enhanced northward ocean transport of anthropogenic carbon through recovery of overturning circulation may be affecting North Atlantic CO2 uptake efficiency
Authors: Brown Pete , McDonagh Elaine , Sanders Richard , Moat Ben , Frajka-Williams Eleanor , King Brian , Carracedo Lidia , Watson Andrew , Schuster Ute , Flohr Anita , Johns William , Baringer Molly
Published: March 2024

Of the additional carbon dioxide added to the atmosphere by human activities the ocean absorbs approximately a quarter, with a disproportionate fraction accumulating at depth in the North Atlantic due to the combined action of northward ocean transport (through the meridional overturning circulation) and strong air-sea fluxes. Combining repeat hydrography with circulation estimates from the RAPID mooring array at 26N it was found that between 2004 and 2012 these two processes were roughly equal in magnitude, but decreasing ocean transports were tipping the balance more towards air-sea uptake over time as the AMOC weakened. New observations from 2012 to 2022 show that this process has now reversed - a recovering AMOC combined with increasing loadings of carbon is now transporting substantially greater quantities of anthropogenic carbon northwards into the North Atlantic. Changes in regional air-sea fluxes suggests that the increased northward ocean carbon transport may be affecting CO2 uptake capacity downstream.
Selection of bundle block adjustment parameters in UAV surveys of underground mining-induced displacements
Authors: Ćwiąkała Paweł , Pastucha Elzbieta , Puniach Edyta , Gruszczyński Wojciech
Published: March 2024

Measurements for determining terrain surface deformations that are caused by underground mining require high measurement accuracies to be achieved. Uncrewed aerial vehicles (UAVs) have not been widely used for this purpose. The presentation presents the process of selecting optimal bundle block adjustment (BBA) parameters for UAV-acquired data. The analyses were carried out for 25 measurement series on a test field of 2 km2. A total of 59 ground control points (GCP) and check points (CP) were used in the study. The analyzed parameters included: the GCP accuracy: 15mm or 25mm, 
the GCP number: 9 or 23, 
the tie point accuracy: 1px or 2px,
the impact of the tie point filtration, 
the impact of the additional corrections of camera calibration (based on the 96-parameter Fourier series) not included in Brown’s model,
the accuracy of the coordinates of the projection centers of the images: the values estimated by the GNSS receiver, or 50mm or 100mm.
The final result of the study is the identification of BBA parameters that allow the highest accuracy of UAV photogrammetry products to be achieved.
Establishment of dune-building grasses in relation to beach moisture, burial and erosion
Authors: Homberger Jan-Markus , van Rosmalen Sasja , Riksen Michel , Limpens Juul
Published: March 2024

Globally, sandy shorelines are among the ecosystems most affected by climate change, driven by rising sea levels and increased frequencies of extreme events. More frequent extreme storm surges increase the risk of flooding, potentially affecting the livelihood of coastal communities and putting pressure on flood defenses. For coastlines relying on sand dunes, flood safety partly depends on how fast dunes can re-establish on a bare beach. In temperate regions, initial development of coastal dunes oftentimes starts with the establishment of perennial grasses such as marram grass (Ammophila arenaria) and sand couch (Elytrigia juncea).  We assessed the establishment probabilities of dune-building grasses in relation to beach soil moisture and bed level change (burial and erosion) under dynamic field conditions. We selected four beaches with a wide range in environmental conditions and sufficient space for vegetation establishment (widths greater than 200 m). 180 blocks within a randomized block design were created, and locally collected plant material was introduced within small 50 x 50 cm quadratic plots. We randomly introduced seeds and rhizome pieces from marram grass and sand couch, leaving one plot untreated to account for natural establishment. All of the plots were re-visited three times throughout the growing season of 2022. Each time, soil moisture (WET-2 sensor, Delta-T Devices), the height of the plots (real-time kinematic positioning system, Topcon), and the number of emerged shoots were recorded.We found that natural establishment occurred throughout the entire growing season, with environmental conditions directly after arrival playing an important role. The establishment probability was significantly influenced by soil moisture. We also found a positive effect of bed level change on establishment when erosion was less than –3 cm and burial was no more than 11 cm. Moreover, we found that locations independent from groundwater (heights > 2.81 m, mean moisture = 5.2%) exhibited significantly lower establishment probabilities during periods of drought.Our results suggest that the recovery and resilience of coastal dunes depend not only on the nature of the extreme event but also on the environmental conditions following a disturbance by storms. While establishment does not appear to be temporally constraint, coastal dunes likely recover quicker when dune building grass establishment is promoted by conditions of moderate burial and sufficient beach moisture. On the other hand, extreme bed level changes and extremely dry conditions following storms likely lead to slower recovery. This might pose a challenge for coastal communities, considering these conditions could arise more frequently in the future due to climate change.
Towards a storyline approach for examining future flood risk: A Central American case study
Authors: Dentith Jennifer , Young Paul , Filipova Valeriya , Butler James , Hawkins Anya , Leedal David , Pascoe Meredith , Styles Kirsty , Walkden Andrew
Published: March 2024

Climate change will impact the probabilities of different weather conditions and make new weather conditions possible, with implications for societal exposure to extreme weather hazards. While there is agreement that the frequency and intensity of many hazards will increase at the global scale, there is uncertainty in the spatial distribution of the changes, which needs to be considered in assessments of future extreme weather risk. Typically, this uncertainty is quantified by exploring the range of hazard intensities across a climate model ensemble for a given climate forcing. An alternative approach is to consider the range of atmospheric circulation changes across an ensemble – the driver of much of the relevant uncertainty – and extract a limited set of “physical storylines”. Rather than viewing an ensemble as a continuum of possibilities from which percentiles can be drawn, this physical storyline approach identifies “scenarios within scenarios”, thereby enabling risk modelers to work with more tractable amounts of climate data, end users to explore a “plausible worst case”, and scientists to focus their efforts on which circulation changes might be most likely.Here, we demonstrate a prototype storyline approach for future flood risk in Central America. We consider how the frequency and intensity of flooding might change by using a pattern-scaling approach to extract the climate signal from climate model output. As a first step towards quantifying the uncertainty in our future flood risk data, we use output from three CMIP6 models that span the range of climate sensitivities and provide different flood storylines for Central America because of their distinct precipitation and temperature trends. We show how return periods for precipitation and streamflow may change under a range of policy-relevant global warming levels, providing useful insights about future surface water and river flooding for the financial, insurance, and development sectors.
Cold pool pockets develop at the bottom of Gale crater (Mars)
Authors: Ruíz-Pérez María , Pla-Garcia Jorge , de la Torre-Juarez Manuel , Rafkin Scot
Published: March 2024

The Curiosity rover has moved more than 31 km from the landing site at the very bottom of the crater and has climbed more than ∼750 m into the Mnt. Sharp foothills over more than five Martian years. A significant change in temperatures and pressures measured by the REMS monitoring weather station aboard the Curiosity rover has been detected during that traverse.On Earth deep valleys, like the ones in Alps, and craters on Mars like Gale accumulate masses of cold air at night, a.k.a. cold pools, at the bottom of the craters. These pockets of cold air change aspects of local micrometeorology at the bottom of a deep valley compared to the slopes. Downslope winds originating from both Mnt. Sharp and crater rims converge at the very bottom of the crater floor and may produce a vortex in the very stable and shallow nocturnal air mass [Rafkin et al. 2016]. This flow would prevent the nighttime accumulation of any tracer along the slopes above the cold pool and facilitate the convergence and accumulation of tracers in the bottom of the crater. The exception is during the northern hemisphere winter (around Ls 270 when strong northerly winds tend to scour the crater air mass day and night [Pla-García et al. in 2019].As Curiosity ascends, we can examine whether these cold air masses exist at the very bottom of the crater and whether the rover moves away from them when reaching a specific height through Mnt. Sharp slopes. One indication is an increase in nighttime temperatures as the rover climbs Mt. Sharp’s slope. Those interannual increments of nighttime temperatures at Gale show a smooth variation within the lower layers before changing scenarios from landing location and tosol’s (Figure). To distinguish this effect from seasonal trends, an analysis of potential temperatures was performed (Figure). Comparing minimum to average temperatures in Figure allows to relate the changes to seasonal or other effects. The figure shows the annual evolution of the Martian air temperature using a Fourier adjustment. Modeling and observations strongly suggest that the rover has ascended to elevations above the cold pool at the bottom of the crater [Ruíz-Pérez et al. 2024 in preparation].
The role of citizen science to assess the spatiotemporal pattern of rainfall events in urban areas: a case study in the city of Genoa, Italy
Authors: Boni Giorgio , Cauteruccio Arianna , Faccini Francesco , Loglisci Nicola , Paliaga Guido , Parodi Antonio
Published: March 2024

Short-duration and high-intensity rainfall events in the Mediterranean region, enhanced by climate change, produce floodings in cities characterized by a limited extension of the urban catchment area, a high percentage of impervious surfaces and the inefficiency of the urban drainage system. In the present work the historic center of the city of Genoa (Italy) was assumed as a case study. In this area, the spatial variability of intense rainfall events is significant, even across a limited portion of the territory as demonstrated by analysing five rainfall time series (12 years of data) recorded at high-resolution from authoritative rain gauges.A specific rainfall event that produced floodings on August 27th - 28th, 2023, is analysed with particular focus on the synoptic and mesoscale analysis and assessing the contribution of citizen science rain gauge stations (provided by Acronet network, see e.g., Fedi et al., 2013) to detect the magnitude and spatial distribution of this event.  The comparison between cumulated rain as recorded by the authoritative and citizen science networks shows that the convective nature of the phenomenon results in extremely diverse effects on the territory with very localized intense showers.The introduction of citizen science observations allowed a better understanding of the spatiotemporal structure of the investigated rainfall event that caused flooding in the study area. In the future, a more structured use of this information, associated to appropriate validation procedures, can provide a fundamental contribution to risk management in densely urbanized areas such as the historic centers of many Mediterranean coastal cities.Fedi, A., Ferrari, D., Lima, M., Pintus, F., Versace, C., Boni, G., (2013). The “ACRONET paradigm”, an “open hardware” project. Open Water Journal, 2(1), 7.This study was carried out within the RETURN Extended Partnership and received funding from the European Union Next-GenerationEU (National Recovery and Resilience Plan – NRRP, Mission 4, Component 2, Investment 1.3 – D.D. 1243 2/8/2022, PE0000005) and from the European Union's Horizon 2020 I-CHANGE project ( https://cordis.europa.eu/project/id/101037193).
Quaternary evolution of the Danube along Lower Danube Gorge (Iron Gates) and Oltenia Plain (Romania, SE Europe) – a literature review
Authors: Perșoiu Ioana , Cruceru Nicolae , Rădoane Maria , Preoteasa Luminița , Ruszkiczay-Rüdiger Zsófia
Published: March 2024

Recent investigations on the sedimentary infill of the western Dacian Basin suggest that between ~4.8 Ma and 4.2 Ma (Dacian) the Danube and its tributaries formed a deltaic front at the exit from the Lower Danube Gorge (LDG) known also as Iron Gates. The appearance of a large fluvial system (the proto-Danube) connecting the two basins was dated to ~4.0 Ma with the water course becoming fully formed and discharging into the Black Sea after ~3.7 Ma.In the present paper, the emphasis falls on the Quaternary history of the Danube in the area of the LDG and the Oltenia Plain, the western extremity of the Dacian Basin. The proposed review summarizes investigations of geomorphology and fluvial sedimentology in the region performed during the last 100 years. Morphological, sedimentological, tectonic, and relative chronological information is brought together to advance an overview of the spatial distribution of terrace fragments, their relative altitudes, associated sedimentary structures, available relative chronological frameworks (based mainly on macro- and microfossils) and documented minor deformations associated with local tectonic structures.During the Quaternary, incision of the Danube at the LDG was estimated to be over 250 m. This incision corresponds to a number of at least 7 levels of strath terraces, preserved in a fragmentary way along the narrow passages but better conserved in the successive local tectonic depressions along the LDG. Here 7-10 terraces have been described, among which the lowest 5-6 were attributed to the Quaternary.Downstream of the LDG, the Danube developed a large alluvial fan during the Early Quaternary, the remains of which are currently located at over 180 - 200 m r.a., while in the last ~1 Ma it developed a system of 7 (8?) terraces from ca. 140 - 170 m to 4-7 m r.a. These alluvial terraces attest for a constant southward migration of the Danube to its current position, under the influence of local subsidence and/or of large amount of incoming sediments deposited by the tributaries arriving from the north, draining the southern flanks of the uplifting Southern Carpathians.Through this analysis, we aim to highlight the characteristics of the Quaternary history of the Danube in two distinct sectors: the LDG and the area downstream to it, the Oltenia Plain down to Jiu River, the first important tributary of the Danube downstream to the LDG. The final objective of this exercise is to create the framework for the first investigations of numerical age determination of terraces along the lower sector of the Danube.Funding: PNRR-III-C9 2022 - I8, project code CF 253/29.11.2022, no: 760055/23.05.2023.
Monitoring water level and lake extent change with nadir-altimeters and SWOT
Authors: Uyanik Hakan , Chen Jiaming , Fenoglio Luciana , Kusche Jürgen
Published: March 2024

Water level and lake extent are estimated from combined in-situ, Sentinel-3 and Sentinel-6 nadir altimeters and SWOT-altimetry. Accuracy and precision of the various techniques are compared, the goal is the validation of the new SWOT data in the river Rhine and in Swiss lakes. The main challenge is the interference among multiple water surfaces which contaminate the signal. Fully-focus and Unfocused SAR and individual echoes processed data have a different sensitivity to the signal coming from non-nadir targets. For nadir-altimeters the accuracy and precision of water level depend on the frequency selected for the low level processing. The accuracy ranges from 10-30 cm and depends on the location. The precision is of few centimeters at 80-140 Hz and decreases with increasing frequency selected in low level processing.  SWOT derived parameters are validated against the nadir derived equivalent. A more accurate river slope parameter is expected from the SWOT high spatial resolution data. Water extent is another new parameter from SWOT, which is used to derive river discharge and water storage change. In rivers, Sentinel-3A pass 156, that is parallel to the river centerline for about 30 km, is a test area for a direct comparison of water height, slope and discharge parameters from nadir-altimeters and SWOT.  In lakes, SWOT water level and water extent are validated against in-situ lake bathymetry, water area extent from Sentinel-1 and Sentinel-2 satellite imagery and water level from nadir-altimeters. In its 21-day phase, SWOT is used to monitor storage change of lakes and reservoirs.
Causal networks for quantifying the links of boreal winter atmospheric variability with Mediterranean climate on multiple temporal scales
Authors: Hatzaki Maria , Di Capua Giorgia , Chaniotis Ioannis , Patlakas Platon , Donner Reik , Flocas Helena A.
Published: March 2024

Large-scale atmospheric circulation is the major driver of near surface climatic variability and extremes, with teleconnection patterns being a significant component by connecting climates in remote locations. The recently developed powerful concept of causal effect networks (CENs) enables the detection of causal relationships among a set of actors by removing the confounding effects of autocorrelation, indirect links, and common drivers, retaining eventually only the actual causal links.In this study, we apply the causal discovery algorithm to analyze the causal links among teleconnection patterns and other circulation features of the North Hemisphere and their influence on Mediterranean winter climate variability. We employ different sets of actors and multiple-scale temporal resolution reanalysis datasets to examine the consistency of the CENs across different timescales and to uncover the underlying mechanisms of their links. By investigating the strength of the different remote drivers compared to local drivers, this analysis contributes to a better understanding of the mechanisms controlling the intraseasonal variations in boreal winter circulation over the Mediterranean. In addition, we find that the strength of the causal links is affected by interannual and multidecadal variability, suggesting the potential involvement of external physical mechanisms.
AMOC representation in the North Atlantic in a forced ocean model
Authors: Wett Simon , Rhein Monika , Biastoch Arne , Frajka-Williams Eleanor
Published: March 2024

The Atlantic Meridional Overturning Circulation (AMOC) plays a vital role in the climate of Europe and the North Atlantic region by redistributing heat and freshwater in the Atlantic. Climate model studies project an AMOC decline under global warming in the 21st century. However, they disagree on the magnitude and timescales of the weakening. Thus, assessing model performance regarding the representation of the AMOC remains essential. Observational estimates can serve as important benchmarks to understand AMOC variability in ocean models. AMOC observations at different monitoring arrays in the North Atlantic have shown strong variability on multiple time scales and no long-term trend. We analyze the AMOC at the North Atlantic Changes (NOAC) array line at 47°N in the high-resolution forced VIKING20X model simulation from 1980 to 2021. The mean AMOC strength is within the range of the NOAC observations. However, the VIKING20X AMOC exhibits a decreasing trend from the mid-1990s until 2010. This decrease coincides with significant cooling and freshening in the subpolar North Atlantic in VIKING20X. In agreement with NOAC observations, VIKING20X shows meridional connectivity between the NOAC and RAPID AMOC when the NOAC AMOC leads by about one year, though less distinct. This agreement indicates a common mechanism, determining the meridional connectivity in observations and VIKING20X. These mechanisms must be understood and represented in climate models to make informed projections of the future AMOC and its role in the climate system. Furthermore, ocean models and gridded observational data sets could help complement new approaches to monitoring the AMOC at key locations using novel methods and instrumentation, such as drift-free bottom pressure sensors, which could help resolve the geostrophic reference level.
What are the challenges simulating historical ocean deoxygenation?
Authors: Takano Yohei ,   Ocean Biogeochemistry Modelling Group
Published: March 2024

   This study presents an analysis of the historical upper ocean (0-700m) dissolved oxygen (O2) and heat content changes from a suite of  the Coupled Model Intercomparison Project phase 6 (CMIP6) ocean biogeochemistry simulations. The simulations include both forced ocean-only models (the Ocean Model Intercomparison Project, OMIP1 and OMIP2) and coupled historical simulations from Earth System Models (ESMs)  (CMIP6 Historical). Simulated changes in the O2 inventory and ocean heat content (OHC) over the past five decades spatially and temporally diverge across the models. The multi-model mean and spread of the upper ocean global O2 inventory trend for each of the simulations is 0.03 ± 0.39 × 1014 [mol/decade] for OMIP1,  -0.37 ± 0.15 × 1014 [mol/decade] for OMIP2, and -1.06 ± 0.68 × 1014 [mol/decade] for CMIP6 Historical simulations, respectively. The latest observational trend based on the World Ocean Database 2018 is -0.98 × 1014 [mol/decade],  in line with the CMIP6 Historical multi-model mean, though this recent observations-based trend estimate is weaker than previously reported trends.  A comparison between OMIP1 and OMIP2 simulations suggests that differences in atmospheric forcing such as surface wind explain the simulated divergence across simulations in O2 inventory and OHC changes. An additional comparison between OMIP and CMIP6 Historical simulations indicates that differences in background mean states due to differences in spin-up strategy and equilibrium states result in substantial differences in the climate change response of O2. In this presentation, we will discuss gaps and gaps and uncertainties in both ocean biogeochemistry simulations and observations and explore possible future coordinated ocean biogeochemistry simulations to fill in gaps and unravel the mechanisms controlling the O2 and changes in associated ocean biogeochemical cycles. This presentation is based on the recently published work (Takano et al., 2023).ReferenceTakano Y., Ilyina T., Tjiputra J., Eddebbar Y.A., Berthet S., Bopp L., Buitenhuis E., Butenschön M., Christian J.R., John  J.P., Gröger M., Hayashida H., Hieronymus J., Koenigk T., Krasting J.P., Long M.C., Lovato T., Nakano H., Palmieri J., Schwinger J., Séférian R., Suntharalingam P., Tatebe H., Tsujino H., Urakawa S., Watanabe M., and Yool A.: Simulations of ocean deoxygenation in the historical era: insights from forced and coupled models, Front. Mar. Sci., 10:1139917, doi: 10.3389/fmars.2023.1139917.
End to end simulation chain for flux restitution of the spectral imaging concept Nanocarb
Authors: Khater Léa , Croizé Laurence , Pison Isabelle , Berchet Antoine
Published: March 2024

CH4 is the second anthropogenic contributor to global warming after CO2. Monitoring methane emissions is therefore essential in order to mitigate climate change. Satellite missions have the potential to offer more spatial coverage than ground stations, however their coverage is currently insufficient. This leads to the development of satellite missions that can be envisaged as constellations. For this purpose a concept currently studied is Nanocarb, relying  on the patent  WO2018002558A1 (ImSPOC). This instrument is a compact and robust spectral imaging concept relying on a static array of Fabry-Perrot interferometers to retrieve partial interferograms of the incident radiance. This study is focused on developing and using the appropriate tools and models to simulate the flux restitution performances of a methane focused Nanocarb instrument with two intertwined inverse approaches.We have developed an end-to-end simulation chain of the flux restitution by the instrument Nanocarb. First an atmospheric situation is simulated from an inventory such as TNO's by the chemistry transport model Chimere. Then this atmospheric situation is used to simulate Nanocarb measurements, with a direct and backward ImSPOC conception and processing software called MEDOC which relies on the radiative transfer code 4A-OP. Those simulated measurements have realistic noise added and are used to recover atmospheric methane columns. Eventually this new atmospheric situation allows for the retrieval of atmospheric methane fluxes, thanks to the Community Inversion Framework (CIF), coupled with Chimere. Those fluxes can be compared to the initial situation to quantify the introduced biases.We present this simulation chain, and specifically developments made on Medoc and columns obtained for an atmospheric simulation in the north of France. This simulation chain aims to model the flux retrieval ability of the instrument Nanocarb for point sources and area sources of methane.
Exploring the Hydro-Mechanical Behavior of Fractures Utilizing the mini-SIMFIP Probe
Authors: Schaber Tom , Osten Julian , Jalali Mohammadreza , Cadmus Alexander , Welsing Leonie , Cook Paul , Guglielmi Yves , Fuentes Raul , Amann Florian
Published: March 2024

The SIMFIP (Step-rate Injection Method for Fracture In-situ Properties) probe is a downhole displacement tool designed to measure injection-driven fracture displacement in an isolated borehole interval in three dimensions. The resulting displacement and interval pressure data can be used to estimate fracture characteristics such as fracture stiffnesses, strength and hydraulic properties from borehole measurements. SIMFIP results have also been successfully implemented in a stress inversion routine that allows the calculation of the full stress tensor from a single measurement.As part of the SPINE (Stress Profiling IN Enhanced geothermal systems) project, a laboratory-scale deformation tool, the mini-SIMFIP probe has been developed. The probe, with a diameter of 20 mm and a length of 65 mm, can be installed in laboratory to study the 3D deformation of intact rock and fractures in different type of rocks. Preliminary tests were conducted in a decimeter-scale true triaxial test apparatus containing a cuboid granite sample with an oblique saw-cut laboratory fracture. Two boreholes crossing the fracture can be isolated and equipped with the mini-SIMFIP probe. Fluid injection into the isolated interval opens the fracture or induces hydraulic shearing under anisotropic stress conditions. The resulting dataset can be used to quantify measurement uncertainties associated with the field SIMFIP protocol, to benchmark stress inversion protocols against known stress boundary conditions, and gain better insight into hydro-mechanically coupled processes.
Continuum and particle scale analysis of nutrient gradients in the rhizosphere 
Authors: Lippold Eva , Landl Magdalena , Braatz Eric , Schlüter Steffen , Kilian Rüdiger , Höschen Carmen , Harrington Gertraud , Mueller Carsten W. , Schnepf Andrea , Mikutta Robert , Gocke Martina I. , Lehndorff Eva , Vetterlein Doris
Published: March 2024

Plant roots create chemical gradients within the soil rhizosphere but little information exists on the effect of root types and ages on the distribution of chemical gradients. Research aim was to develop an imaging workflow and to analyze and model the effects of radial root geometry, root hairs, and ages on nutrient gradients around roots.The presented correlative imaging workflow is suitable for targeted sampling of roots in their 3D context and assessing the imprint of roots on chemical properties of the root-soil contact zone at µm to mm scale. Maize (Zea mays) was grown in 15N-labelled soil columns and pulse-labelled with 13CO2 to visualize the spatial distribution of carbon inputs and nitrogen uptake together with the redistribution of other elements. Soil columns were scanned by X-ray computed tomography (X-ray CT) at low resolution (45 µm) to enable image-guided subsampling of specific root segments. Resin embedded subsamples were then analysed by X-ray CT at high resolution (10 µm) for their 3D structure and chemical gradients around roots using micro X-ray fluorescence spectroscopy (µXRF), nanoscale secondary ion mass spectrometry (NanoSIMS), and laser-ablation isotope ratio mass spectrometry (LA-IRMS). NanoSIMS and LA-IRMS detected the release of 13C into soil up to a distance of 100 µm from the root surface, whereas 15N accumulated preferentially in the root cells.Concentration gradients with different spatial extents could be identified by µXRF. The observed concentration gradients were compared to simulated gradients generated by a process-based, radially symmetric 1D rhizosphere model. An accumulation of calcium and sulfur was observed, particularly around old root segments. Our model simulations indicated that this phenomenon originates from the radial structure of the root, leading to enhanced nutrient transport towards the root surface. Gradients of calcium and sulfur could be accurately predicted by the model around a single growing root, when they were mainly caused by sorption.However, at the pore-scale, phenomena like local precipitation, which could be visualized using our methodology, were inadequately accounted for by the classic model approach. Nonetheless, the observed extension of the gradients was well described by the model. The presented approach combining targeted sampling of the soil-root system and correlative microscopy opens new avenues for unravelling rhizosphere processes in situ.    
Analysis of Sea Surface Pressure Climatology and Cyclogenesis Patterns over the Black Sea
Authors: Öztürk Büşra , Kadıoğlu Mikdat
Published: March 2024

Semi-permanent low-pressure centers form as a result of topographical features and atmospheric flows. The precise location and intensity of these centers significantly influence the weather patterns in the surrounding countries. In the same context, the occurrence of cyclogenesis over the Black Sea, often mentioned as the Black Sea Low, significantly impacts the weather conditions in Türkiye. A cyclone must persist throughout the year to be classified as a semi-permanent pressure system, however, the literature indicates the potential existence of high-pressure areas in the Black Sea as well. This study aims to investigate the presence of the Black Sea Low by examining low-pressure centers over the region, to determine the frequency and seasonality of cyclonic activity. The ERA5 dataset with 0.25° resolution is used for the analysis, covering the period from 1940 to 2023. Related variables like mean sea level pressure, sea surface temperature, temperature, wind speed, and total precipitation are examined to investigate the persistence and seasonal variations of the low-pressure center over the Black Sea through synoptic pattern categorizations of cyclogenesis over the Black Sea. The preliminary results indicate a low-pressure pattern on the southeastern Black Sea, which is seasonal and forms during the summer months over the region.