bluuebunny/crossref_metadata_2025 huggingface dataset:
 Is sampling influential on the variations in 13C stable isotopes whilst screening for drought stress in coffee?
Authors: Nakamya Janice
Published: March 2024

IS SAMPLING INFLUENTIAL ON VARIATIONS IN 13C STABLE ISOTOPE WHILST SCREENING FOR DROUGHT STRESS IN COFFEE           Janice Nakamya1,2, Roel Merks3, Rebbeca Hood-Nowtry2, Gerd Dercon1Jeremiah Mwangi4, Silas Makune41 Soil and Water Management & Crop Nutrition Laboratory, Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, 2444 Seibersdorf, Austria 2University of Natural Resources and Life Sciences Vienna, Peter-Jordan-Straße 82, 1190 Vienna 3 Division of Soil and Water Management, Faculty of Bioscience, KU Leuven, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium 4 Kaweri Coffee Plantation, Plot 1 Kitemba 264, Mubende UgandaAn enormous coffee yield gap and subsequent decline in income has been realised from drought, triggering a need for faster screening tool for water stress and estimation of water use efficiency for the commonly grown coffee varieties. However, determining the critical thresholds of drought stress in perennial crops especially in coffee is challenging. Stable isotope measurement of coffee leaves could avail instantaneous measurements as they track the changes at leaf level, there has been limited use of isotopes to monitor drought stress in coffee. Furthermore, using punch leaf samples instead of bulk leaf samples would be faster and cheaper by eliminating grinding.  The method requires homogenous sampling to provide representative samples and ensure quality results, suggesting detailed understanding of variations in d13C at coffee leaf level.  The study was conducted on commonly grown 6 old clones’ varieties of Robusta coffee, each in a 16-year-old 15 by 15m trail plot at Kaweri Coffee plantation Mubende, Central Uganda. With a specific aim of establishing (1) Whether d13C varies within the different leaf ages, leaf symmetry and sample position on the leaf (Fig.1). Separate punch leaf samples were obtained on young fully grown, below, and old pair of leaves on the left and right side of the apex, middle and rare of the lamina.  The results reveal a significant variation in d13C between young and old leaves but not with the pair in between them. Furthermore, a leaf pair is not the same in terms of d13C but it does not matter which position on the leaf the punched sample is obtained from.  Implying, for the best representation, coffee punch sample would be from any position of an old leaf.   
Hydro-economic assessment of the impact of climate and socio-economic changes on water resources in the MENA region
Authors: Asad Samar , Sahu Reetik-Kumar , Fridman Dor , Willaarts Barbara , Kahil Taher
Published: March 2024

The Middle East and North Africa (MENA) region is struggling with a continuous decline in water availability, attributed to climate change and variability, exacerbating the existing water scarcity. At the same time, factors such as population growth, urbanization, economic development and mismanagement further stress the scarce water resources. This study aims to assess the impact of climate and socioeconomic changes on the availability and use of water resources and related economic and environmental conditions in the MENA region at high spatial and temporal resolutions, in order to provide insights into cost-effective and sustainable water management options to reduce water scarcity. To do so, we apply a set of potential future climate and socio-economic change scenarios, based on combinations of the Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) and informed by a review of regional development visions and consultations with key regional experts. Scenario simulations are conducted using the hydro-economic model ECHO in combination with the hydrological model CWatM at subbasin and monthly levels for the whole MENA region. Results of this study shows the escalating deficit in renewable water resources and the rising water demand, exacerbating water scarcity across the majority of the MENA countries. Therefore, meeting the increasing water demand becomes an even greater challenge in the region. To address this challenge, our results underscore the need for a more efficient allocation of water resources among sectors and subbasins at the regional level and a shift towards more advanced water conservation and reliable water supply technologies.Keywords: Hydro-economic assessment, Water scenarios, Water scarcity, MENA region.      
The Gassino stone in the architecture of Torino (Italy): different features for different uses
Authors: Bellopede Rossana , Borghi Alessandro , D'Atri Anna , Gambino Francesca , Marini Paola , Martire Luca , Dino Giovanna , Storta Elena
Published: March 2024

The Gassino Stone, the most widely used carbonate sedimentary rock in Torino until the XIX century, is also known as Calcare di Gassino or Gassino Marble (Borghi et al., 2014). It was quarried from the Torino Hill domain near Torino and its formation can be referred to the Eocene. It is a biocalcirudite containing mainly red algae, macroforaminifera, bivalves, echinoids, and locally abundant intraclasts of biocalcarenites.Although it has not been exploited for a long time, its occurrence in the city is still considerable. Its uses began in the end of the 1600 till mid 1800 and was installed not only in the churches but also in the historical buildings in plinth, columns, fireplaces and furnishings (Campanino et al., 1991).It is possible to find applications of this rock in many famous historical buildings of Torino and surroundings such as in the colonnade of the courtyard of the Rectorate of the Torino University, in the portal of Palazzo Carignano, on the façades of the Santa Cristina Church and of the Torino Town Hall of, and in the Basilica of Superga external columns.In the interior it has been usually installed with polished finishes (for example in the San Lorenzo church in the center of Torino). This kind of surface finishes gives a brownish aspect to the stone, in addition to a sense of compactness. When instead the Gassino stone is installed outdoor, with increasing time of exposure, its colour turns white and the compactness decreases emphasizing the presence of nodules consisting of calcareous red algae and intraclasts surrounded by thin clay seams. The portal of  Palazzo Carignano  represents the best example of the differential decay of this kind of stone outdoors, while the holy eater font in San Lorenzo church is the perfect example of optimal maintenance indoors.
Long range lidar for short term wind predictions for offshore wind parks
Authors: Bade Janina , Kirtzel Hans-Jürgen , Heinze Leon , Markmann Piet , Peters Gerhard , Bollig Christoph , Ulonska Sebastian , Jordan Florian , Huschenbeth Guntram
Published: March 2024

A novel lidar prototype for horizontal Doppler wind measurements with more than 30 km maximum range is presented. The request for such long-range measurements arose from the development of methods for improved prediction of potential and actual feed-in of wind power from offshore wind farms in the project WindRamp. The target is a short-term prediction horizon of up to 30 minutes.The coherent lidar module is based on a robust fiber amplifier architecture developed within the project. This enables deployment in harsh environments in the future, e.g. at offshore wind farms. The emitted laser beam is eye save (class 1M).In order to emulate operating conditions of an offshore platform, the system was deployed at the mouth of the Elbe river at 10 m above sea level with unobstructed view in a broad SW-sector. Scans between 204° and 304° azimuth at 0.35° Elevation were performed. The averaging time was 1 s and the angular speed 0.6° s-1.The lidar performance is demonstrated by observations of wind fronts propagating through the observed area. The weather in North Germany during winter 2023/24 was characterized by unusual persistent precipitation, low hanging clouds and fog, which are unfavourable conditions for lidar operation. Therefore, the observed availability of valid data versus range represents a conservative estimate of the system’s potential.
Drivers of compound drought-heat extremes across recent decades
Authors: Kroll Josephin , Stephan Ruth , Rieder Harald , Hesselbjerg Christensen Jens , Orth Rene
Published: March 2024

The joint occurrence of droughts and heat waves is expected to change with advancing climate change. While drought and heat themselves can already have major impacts on ecosystems and society, their compound occurrence can lead to amplified effects. Previous studies have analyzed changes in the occurrences frequency of compound drought-heat events and found increasing trends in some regions. In this study, we revisit these occurrence trends and additionally analyze the mechanisms that couple drought and heat as well as their changes in space and time. Considering drought as deficit of soil moisture and heat as an extreme temperature, evapotranspiration (ET) is the main physical process connecting both extremes. Therefore, we focus particularly on ET anomalies, because higher-than-normal ET during drought-heat events indicates that heat is inducing drought (heat → drought) as high temperatures lead to high vapor pressure deficit which increases ET that in turn depletes soil moisture. Vice versa, lower-than-normal ET suggests drought is triggering hot temperatures (drought → heat) as low soil moisture limits ET such that more of the incoming radiation is partitioned to sensible heat flux and hence warming the air. To better understand the underlying controls of these ET anomalies, we analyze their drivers by considering anomalies of precipitation, radiation, vapor pressure deficit and Leaf Area Index, which are in turn linked to anomalies in atmospheric circulation. Finally, we compare the relevance of these drivers, and of the drought → heat vs. heat → drought mechanisms in space, and link them with aridity and land cover type. In our analysis, we employ weekly data from the ERA5 reanalysis alongside gridded products derived with machine learning methods which were trained with in-situ observations. We define drought and heat with a percentile based approach filtering the lowest (< 5th percentile) absolute soil moisture values and highest (> 95th percentile) absolute temperatures at each grid cell. Understanding the mechanisms behind compound drought-heat extremes can help improve related forecasts, and to validate and constrain model projections of trends in these events. 
In-situ Saharan dust observations over the Eastern Mediterranean with an uncrewed aircraft system
Authors: Savvakis Vasileios , Schön Martin , Bramati Matteo , Bange Jens , Platis Andreas
Published: March 2024

The Saharan desert is the main source of mineral dust in the atmosphere, and its presence in the air can have a significant impact on the solar radiation budget. In evaluating the radiative effect of airborne mineral dust, aerosol charge may be a critical factor. This space charge and its relationship to particle concentrations is not taken into account by current model simulations, and such in-situ measurements are hardly available. In this work, a novel sensor network equipped on an uncrewed aircraft system (UAS) of type MASC-3 was employed for vertical profiling of Saharan dust particle concentrations, meteorological (temperature, relative humidity and wind field) parameters and turbulent kinetic energy (TKE), during a dust event that occurred in Orounda, Cyprus in April 2022. The MASC-3 performed profiles up to 3000 m altitude, and identified the vertical extent of the dust cloud, which was located between 1900 and 2500 m. We were able to capture the evolution of the event over several days, and additional numerical simulation and remote sensing observations verify the results. During the first day of measurements, when dust load was the highest, charge data from the MASC-3 also allowed for investigation of aerosol concentrations and dust electrification. For the first time, this innovative sensor system provided in-situ UAS measurements of the aforementioned quantities and described the dust event in detail, and with high resolution. Considerations on aircraft charging, the effect of turbulent levels and local meteorology, on the space charge / aerosol data collected by the MASC-3, as well as probing Saharan dust events more generally, are elaborated for further related research.
Predisposition of European beech to drought-induced die-off along a climate gradient in Northern Bavaria
Authors: Žmegač Anja , Zang Christian S.
Published: March 2024

Climate change is strongly influencing global shifts in forest ecosystem dynamics. There has been a twofold increase in canopy mortality within the temperate forests of Europe in the past thirty years. The trend has been further intensified by recent drought episodes occurring between 2018 and 2020, leading to increased instances of die-offs and reduced vitality among key tree species.In central Europe, notably in Germany, European beech (Fagus sylvatica L.) stands out as a tree species with high ecological and economic significance. Recent severe drought conditions led to substantial vitality loss and mortality. Nevertheless, there was considerable diversity in how individual beech trees responded to drought, with some trees in the same location being heavily impacted while others remained seemingly unaffected. Factors influencing this uneven response are still not fully understood.In this study, we gathered 600 beech tree-ring width series from 13 sites located across Northern Bavaria, along a climatic gradient. We explore the differences in growth between two groups of trees (damaged/vital) using a dendroecological approach. We evaluated loss of vitality through the implementation of mortality and critical slowdown indicators such as long-term growth decline or changes in climate memory, as well as climate/growth relations and growth synchrony indicative of changing growth limitations.While we did not find significant differences between groups in terms of climate memory and drought sensitivity, our results showed a divergence in the growth patterns of vital and damaged trees following repetitive exposure to drought events. We detected higher growth rates of damaged trees prior to the last three decades, after which their growth rates declined stronger than vital trees. Our results suggest that faster-growing beech trees may be more susceptible to drought-induced mortality, which is in line with findings of higher vulnerability of faster-growing trees to environmental stressors.
Assessing the sedimentary carbon sink for climate change mitigation - the need for transdisciplinary cooperation
Authors: Holtappels Moritz , Daewel Ute , Kuhlmann Jannis , Porz Lucas , Taylor Bettina , Wallmann Klaus , Zhang Wenyan , Ziebarth Nadja , Kasten Sabine
Published: March 2024

Shelf sediments represent one of the largest natural carbon sinks on earth. At the same time, shelf regions are increasingly affected by human activity, disturbing sediment reservoirs directly by bottom trawling and offshore construction, or altering the carbon supply by changing river discharge, sediment management and the trophic status and food web of the sea. As global warming progresses, the sedimentary carbon sinks are becoming increasingly important in climate change mitigation measures. Thus, there is a need for in-depth knowledge of both, the dynamics and vulnerabilities of the sedimentary carbon sinks, as well as the legal and political options to protect their sequestration efficiency from human disturbances. Here we report on the transdisciplinary research project APOC, which addresses the Anthropogenic impacts on the cycling of Particulate Organic Carbon in the North Sea. Important results of the project include the quantification of sedimentation rates in the accumulation areas of the German Bight and the Skagerrak, assessing the factors that enhance organic carbon storage and the determination of the sources of deposited carbon. As major anthropogenic disturbances, the effects of bottom trawling and wind farm construction on benthic carbon storage were investigated and assessed. Bottom trawling in particular was significantly decreasing the benthic carbon storage due to a multitude of coupled physical and ecological effects. However, at the environmental policy level, it became clear that sedimentary deposits are not sufficiently recognized as valuable carbon sinks, although their storage capacity is believed to be much higher than that of blue carbon ecosystems at similar latitudes. While the project was staffed mainly with natural scientists, important expertise in environmental policies was provided by the marine protection office of the BUND, one of the largest environmental NGOs in Germany. As a fully-fledged project partner, BUND made it possible to recognize the relevance of the various project focal points for the environmental policy arena throughout the entire project. In turn, the policy experts were able to distribute the latest scientific findings to the relevant political decision makers. In effect, the transdisciplinary cooperation within the project not only produced valuable scientific results, but also numerous expert briefings for environmental policy at all levels, from local authorities to the EU Parliament, emphasizing the importance of protecting sedimentary carbon sinks for climate change mitigation measures. Key to this outcome was the continuous exchange of scientific findings and practical environmental policy knowledge, which kept all participants focused on the societal relevant objectives that were originally pursued with the project funding.
EMODNET Geology delivers marine geological data products from Europe’s seas and beyond
Authors: Kaskela Anu , Vallius Henry , Kihlman Susanna , Kotilainen Aarno T. , Alanen Ulla , Partners EMODnet Geology
Published: March 2024

Effective maritime spatial planning, coastal zone management, management of marine resources, environmental assessments and forecasting require comprehensive understanding of the seabed. The European Commission established the European Marine Observation and Data Network (EMODnet) in 2008 and in response to these needs. The EMODnet concept is to assemble existing but often fragmented and partly inaccessible marine information into harmonized, interoperable, and freely available data layers and data products encompassing whole marine basins. As the data layers and data products are open for use, the program is supporting any European maritime activities in promotion of sustainable use and management of the European seas.The EMODnet Geology project is delivering integrated and harmonized geological data products that include seabed substrates, sediment accumulation rates and seabed erosion index database, seafloor geology including lithology and stratigraphy, Quaternary geology and geomorphology, coastal behaviour, geological events such as submarine landslides and earthquakes, marine mineral resources, as well as submerged landscapes of the European continental shelf at various timeframes. All data products are openly available at the EMODnet Central Portal. They are presented at a scale of 1:100,000 or finer but also coarser scales to ensure maximum areal coverage. The current EMODnet Geology project phase is executed by a consortium of 40 partners and subcontractors which core is made up by members of European geological surveys (EuroGeoSurveys) backed up by other partner organizations with valuable expertise and data.The EMODnet concept is expanding beyond European Seas, as also the Caspian and the Caribbean Seas are included in the geographical scope of the EMODnet Geology project. During the current project phase, the focus is to ensure collection and inclusion of Caribbean Sea data to the geology data layers on the EMODnet Central portal. For this purpose, EMODnet Geology is establishing collaboration with Asociación de Servicios de Geología y Minería Iberoamericanos (ASGMI) that is active in the Caribbean Sea area. Previously selected methods have been shared with the EMODnet PArtnership for China and Europe (EMOD-PACE) project (2019-2022).The EMODnet Geology project is funded by The European Climate, Environment, and Infrastructure Executive Agency (CINEA) through contract EASME/EMFF/2020/3.1.11 - Lot 2/SI2.853812_EMODnet – Geology.Discover Europe’s seabed geology at: https://emodnet.ec.europa.eu/en/geology
Southern Ocean response and sensitivity to idealized freshwater perturbation experiments
Authors: Farneti Riccardo
Published: March 2024

Recent observations show that mass loss from Antarctic ice sheets and ice shelves is accelerating and is projected to increase further in the coming decades. The resulting freshwater input from melting of the grounded ice sheet and ice shelves is expected to have significant impacts on Southern Ocean dynamics that could also feedback onto the global climate system and its future changes. However, most state-of-the-art coupled models do not include interactive ice sheets and shelves, resulting in large uncertainty in future climate projections. Additionally, the physical response within the Southern Ocean and beyond remains elusive and largely dependent on the model used and the experimental design.Here, we present results from a model participating in the Southern Ocean Freshwater Input from Antarctica (SOFIA) initiative, an international model intercomparison project in which freshwater is added to the ocean surrounding Antarctica to simulate the otherwise missing ice-sheet mass loss. Contrary to most models participating in SOFIA, we have performed our experiments with an ocean-sea ice model in which sea surface salinity restoring is deactivated and previously computed restoring-induced surface fluxes are provided at the ocean surface in order to keep a stable climate. Besides the missing atmospheric feedback, an ocean-only SOFIA experiment allows the investigation of the ocean's response to Antarctic freshwater discharge and, through the comparison with SOFIA coupled models, the quantification of the role of atmospheric feedbacks.Preliminary results, based on a suite of experiments using varying strengths of the freshwater perturbation, are presented for both Southern Ocean physics and dynamics, with implications for the global circulation.
Unravelling the Patagonian Local Last Glacial Maximum and its Deglaciation History from a Modelling Perspective
Authors: Castillo-Llarena Andrés , Retamal-Ramirez Franco , Bernales Jorge , Jacques-Coper Martin , Prange Matthias , Rogozhina Irina
Published: March 2024

During the Marine Isotope Stages (MIS) 2-3, the Patagonian ice sheet (PIS) stretched along the southern Andes from 55°S to 38°S. Based on Glacial geomorphological and geochronological evidence, its western margin reached the Pacific Ocean, while its easternmost sectors were characterised by terrestrial lobes that fed large paleo-glacial lakes. Previous studies suggest that the maximum extension of PIS was reached towards the end of the MIS 3. However, uncertainty remains regarding the glacial and climate evolution that led to its maximum extension in asynchrony with the Northern Hemisphere ice masses and Antarctica.We present an ensemble of transient numerical simulations of the PIS that were carried out through the MIS 3 and MIS 2, aiming to determine the range of climate conditions that match the field-derived ice sheet geometries and climate history of the Patagonian ice sheet prior the global LGM, which corresponds to the timing of the local glacial maximum and its subsequent deglaciation. Furthermore, we bracketed the spread in possible ice volumes and sea level contributions originating from uncertainties in the internal parameters and external forcings. The model ensemble is built using the ice sheet model SICOPOLIS forced by phases 3 and 4 of the Paleoclimate Modeling Intercomparison Project (PMIP). The transient simulations are based on a glacial index method by using a combination of Patagonian offshore records and Antarctic cores. Our results indicate that the regional climate conditions required to reproduce a realistic growth and demise of the PIS through the Late Quaternary are not captured by coarse-resolution global climate models, implying the need of climate models with high spatial resolution and a well-constrained ice mask, which could reproduce the necessary cooling to promote the adequate growth. Our results also suggest that the MIS3 should have witnessed colder conditions than those modeled at the LGM by global climate models to realistically simulate the evolution of the PIS in agreement with geological archives.
Process-based 3D groundwater flow model to simulate current and future stream intermittence in headwaters
Authors: Abhervé Ronan , Roques Clément , de Dreuzy Jean-Raynald , Datry Thibault , Brunner Philip , Longuevergne Laurent , Aquilina Luc
Published: March 2024

While the role of climate conditions in controlling streamflow intermittence is well recognised, the assessment and modelling of the role of groundwater remains a challenge. In this study, we use process-based 3D groundwater flow models to simulate stream intermittency in groundwater-fed headwaters. Streamflow measurements and stream network maps are considered together to constrain the effective hydraulic properties of the aquifers. The modelling framework has been applied and validated in pilot catchments with unconfined crystalline aquifers (France) with contrasting geomorphological settings. We present the calibration framework, the analysis of uncertainties and discuss the underlying mechanisms governing the different dynamics of streamflow intermittency. The models are then used to predict streamflow intermittence under future climate scenarios. Intuitively, with decreasing recharge rates, systems with lower storage capacities lead to higher water table fluctuations, increasing the proportion of intermittent streams and reducing future perennial flows. However, the pilot sites reveal nuanced feedback mechanisms among future climate variations, groundwater recharge dynamics, and stream intermittence, where the geomorphic characteristics of the landscapes are key to regulating these feedbacks.
Warm mean annual air temperatures during Miocene to Pleistocene central Arabian humid periods
Authors: Schroeder Julian , Markowska Monika , Vonhof Hubert , Scholz Denis , Weber Michael , Boivin Nicole , Groucutt Huw S. , Petraglia Michael D. , Martinez-Garcia Alfredo , Krüger Yves , Meckler Anna Nele , Fiebig Jens , Nicholson Samuel L. , Haug Gerald
Published: March 2024

The hydroclimate change in the hot and arid Arabian Desert under anthropogenic global warming is a subject of ongoing discussions. Climate models project rising mean annual temperatures coupled with decreasing precipitation averaged over Saudi Arabia with regional variance (Almazroui, 2020). Stable isotope analysis on a combined speleothem record from central Arabia revealed recurring local humid periods during globally warmer intervals over the past ~8 million years (Markowska et al., in review). The speleothem record showed a long-term drying trend towards present, which may potentially be controlled by temperature change. The present study aims to reconstruct mean annual air temperatures (MAATs) of central Arabia during humid periods. These temperatures provide valuable benchmark data for past and future climate models in a region where terrestrial climate archives are scarce. Recent advances in speleothem-based paleothermometry facilitate extracting robust MAATs. We present data from several independent paleothermometers: Fluid inclusion isotopes (de Graaf et al., 2020), TEX86 (Meckler et al., 2021; Wassenburg et al., 2021), fluid inclusion microthermometry (Krüger et al., 2011), and dual clumped isotopes (Bajnai et al., 2020). These reconstructions show that recurrent wet intervals during the Miocene to Pleistocene in the Arabian Peninsula occurred at warmer than modern MAATs. We note, however, that temperature is not the only driver of humidity in the Arabian Peninsula and that both dry and humid periods likely existed under a warmer than today’s climate. Therefore, these observations cannot directly be interpreted as indicator that anthropogenic global warming will lead to future wet conditions in Saudi Arabia. Overall, we provide novel quantitative paleoclimate parameters that can inform climate model experiments leading to improved predictions for future climate scenarios.
Determination of physical heights via time transfer 
Authors: Lachmann Klarissa Emma , Müller Jürgen
Published: March 2024

We present a project of the research unit (RU) 'TIME' (Clock Metrology: A Novel Approach to TIME in Geodesy) which aims to determine gravity potential or height differences between remote sites by comparing optical clocks. A strontium optical lattice clock at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig will be connected with the German Research Centre for Geosciences (GFZ) in Potsdam through a delay-compensated optical fiber. Then, optical time transfer is carried out between the geodetic observatories in Potsdam and Wettzell (where a second optical clock will be operated) via the Atomic Clock Ensemble in Space (ACES) using the Satellite Laser Ranging (SLR) telescopes. The key innovation is using time transfer, not frequency and optical free-space links over an extended period to determine physical height differences. Challenges include clock/link variations, atmospheric effects, visibility constraints and data gaps, etc. We investigate the major error sources and apply corrections like tidal effects. This approach showcases accurately transferring physical heights via time transfer and demonstrates the RU’s time concept for integrating geometric and physical heights in future height systems, especially for Global Geodetic Observing System (GGOS) core stations like the Geodetic Observatory Wettzell (GOW).In this presentation, we introduce the principles, special properties and challenges of this specific measurement scenario. We also provide preliminary numbers for the expected accuracies of the various components and the resulting height difference based on simulations.We acknowledge the support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 490990195 – FOR 5456.
Atlantic meridional nutrient transport 2004-2018 timeseries: insights into inorganic nutrient pool reorganization by the AMOC 
Authors: Carracedo Lidia I. , McDonagh Elaine , Sanders Richard , Moore Mark , Mercier Herlé , Brown Pete , Torres-Valdés Sinhué , Mawji Edward W. , Baringer Molly , Smeed David , Rosón Gabriel
Published: March 2024

North Atlantic (NA) biological productivity and resulting carbon uptake (Biological Carbon Pump, BCP) are supported by the northward transport of nutrients by the upper limb of the Atlantic Meridional Overturning Circulation (AMOC). Changes in the strength of the AMOC are subject to influence ocean nutrient cycling and the efficiency of the BCP. In this study, we present evidence for non-steady state behaviour based on 14 years of observations (2004-2018) at 26.5°N. Our results show significant (>80%) nutrient transport variability tightly related to AMOC alongside predominantly net southward nutrient transport exceeding total nutrient sources. Changes over the observational period indicate: i) increasing NA BCP efficiency (remineralized:preformed ratio); ii) decreasing NA nutrient inventory, except towards the end of the period when the system was closer to balance.
Small-scale Structure of the Martian Mantle
Authors: Charalambous Constantinos , Pike Tom , Fernando Benjamin , Samuel Henri , Bill Carys , Lognonné Philippe , Banerdt Bruce
Published: March 2024

The InSight mission's SEIS instrument has provided a unique opportunity to probe the deep interior of Mars. This seismic exploration of the Martian interior has emerged as a promising avenue for revealing the enigmatic geophysical properties and dynamic processes within the planet's mantle.In this study, we present an analysis of the seismic signature of marsquakes which transit deep into the mantle, providing crucial information on the seismic velocity profile and potential heterogeneities. The quakes show a characteristic late emergence of the first energy at higher frequencies which can be analysed as due to the scattering of seismic energy as it transits the mantle. From this we are able to quantify the size distribution of the mantle's small-scale heterogeneity as well as to constrain the rheological properties and convective vigor of the Martian mantle.As unlike Earth, Mars has sealed its mantle contents under a stagnant lid, we use our observations to provide evidence about the early stages of planetary formation and differentiation on Mars. Our findings contribute to the better understanding of the Martian mantle's geodynamics and allow a comparative assessment of the evolution of planetary interiors that likely apply to other planets that lack plate tectonics.
Unveiling plasma energization and energy transport in the Earth’s Magnetospheric System through multi-scale observations: the science of the Plasma Observatory mission
Authors: Retinò Alessandro , Marcucci Maria Federica ,   Plasma Observatory Team
Published: March 2024

Energetic plasma is everywhere in the Universe. We observe plasma energization and energy transport in a variety of cosmic plasmas, such as planetary magnetospheres, stellar coronae, supernova remnant shocks, accretion disks, and astrophysical jets. The Earth’s Magnetospheric System is a key example of a complex and highly dynamic cosmic plasma environment where massive energy transport and plasma energization occur and can be directly studied through in situ spacecraft measurements. Despite the large amount of available in situ observations, however, we still do not fully understand how plasma energization and energy transport work. This is essential for understanding how our planet works, including space weather science, and is also important for the comprehension of distant astrophysical plasma environments. In situ observations, theory and simulations suggest that the key physical processes driving energization and energy transport occur where plasma on fluid scales couple to the smaller ion kinetic scales, at which the largest amount of electromagnetic energy is converted into energized particles. Remote observations currently cannot access these scales, and existing multi-point in situ observations do not have a sufficient number of observation points. Plasma Observatory will be the first mission having the capability to resolve scale coupling in the Earth’s Magnetospheric System through measurements of fields and particles at seven points in space, covering simultaneously ion and fluid scales in the Key Science Regions where the strongest plasma energization and energy transport occurs: the foreshock, bow shock, magnetosheath, magnetopause, magnetotail current sheet, and transition region. By resolving scale coupling in fundamental plasma processes such as shocks, magnetic reconnection, waves and turbulent fluctuations, plasma jets, field-aligned currents and plasma instabilities, these measurements will allow us to answer the two Plasma Observatory science questions (Q1) How are particles energized in space plasmas ? and (Q2) Which processes dominate energy transport and drive coupling between the different regions of the Earth’s Magnetospheric System? Plasma Observatory will also address important additional science targets such effects of ionospheric processes on the Magnetospheric System (e.g. ion outflows), outer radiation belts processes, solar wind physics and space weather science, which will increase  the scientific return of the PO mission. Going beyond the limitations of current ESA/Cluster and NASA/MMS four-point constellations, which can only resolve plasma processes at individual scales, Plasma Observatory will  transform our understanding of the plasma environment of our planet with a major impact on the understanding of astrophysical plasmas too.
Attribution of forest disturbance agents in the European Alps: a multidecadal analysis based on Landsat time series
Authors: Morresi Donato , Domanico Matteo , Marzano Raffaella , Garbarino Matteo
Published: March 2024

Alpine forests have been shaped by human and natural disturbances for millennia, resulting in highly heterogeneous and fragmented landscapes. Interactions between land use change and natural disturbances have been observed in recent decades. In addition, climate change is altering the disturbance regime in many forest ecosystems, including those in the Alps, by increasing the severity, extent and frequency of natural disturbance events. In this study, we aimed to attribute the disturbance agent to forest patches that experienced stand-replacing and non-stand-replacing events during the last four decades in the European Alps. In particular, we considered both natural disturbance agents, i.e., wind, fire, snow, insects, ice, and drought, and human activities. The latter included both primary and secondary disturbances, i.e., salvage logging following a natural disturbance. We trained an eXtreme Gradient Boosting (XGBoost) machine learning model using disturbed forest patches detected annually by an automated algorithm based on Landsat time series from 1984 to 2022. We obtained information on the disturbance agent using both historical field data from several European countries and visual interpretation of remote sensing data, e.g., Landsat imagery, aerial orthophotos, and high-resolution satellite imagery. We built the final classification model after selecting predictor variables from several disturbance, topography, patch, and climate-related metrics. Preliminary results showed that the model had good predictive performance, as highlighted by the accuracy metrics obtained from a fivefold cross-validation approach, i.e., Cohen’s Kappa equal to 0.81 and balanced accuracy of 0.82. The elevation range, pre-disturbance spectral values, the climate moisture index, and the range of the spectral change magnitude of each disturbed forest patch were among the most important variables. In particular, the elevation range emerged as a key predictor for discriminating between natural and anthropogenic disturbances. Similarly, pre-disturbance spectral values were important for distinguishing between certain natural disturbances, such as windthrows and snow avalanches. Spatially explicit results from this study are expected to allow a thorough characterisation of the changes in disturbance regimes in the European Alps that have occurred over the last four decades, and to provide useful information on the main drivers that have determined these recent shifts.
Dynamics of Plateau Growth: Geodynamic Modeling of the East AnatolianPlateau Uplift Through Double Subduction Processes
Authors: Çetiner Uğurcan , van Hunen Jeroen , Valentine Andrew P. , Göğüş Oğuz H. , Allen Mark B.
Published: March 2024

The Turkish–Iranian Plateau was formed by the collision between the Arabian andEurasian plates, commencing along the Bitlis-Zagros suture in the Late Eocene (~30-35 Ma). This region, commonly partitioned into the East Anatolian Plateau and theIranian Plateau, is associated with significant differences in terms of lithosphericstructure despite an overall average of ~2 km. The geodynamic evolution of EastAnatolia is represented by a double subduction system, where the two branches ofNeo-Tethys were subducting beneath Eurasia, constantly accumulating accretionarymaterial that forms the bulk of the plateau today (i.e., East Anatolian AccretionaryComplex). Seismic evidence demonstrates that the region has unusually thin MOHO(~35 km around Lake Van region) while the whole area is formed mostly by oceanic(accretionary) material and is underlain by no or very thin mantle lithosphere. Theuplift of East Anatolia is attributed to slab break-off and slab peelback (delamination),combined with crustal shortening. However, the intricate plate dynamics arising fromsuch a double subduction system, controlling plateau formation remains unclear.Here, we conducted 2D numerical experiments and comparative model sets indicatethat, in a double subduction system like Eastern Anatolia, the mechanisms of slabbreak-off and peelback heavily depend on the rheology of the subducting plates andthe coupling between the overlying and subducting plate along the trenches. In casesof strong coupling between subducting and overlying plates, we observed anamalgamation of the two subducting plates as they converge, potentially resulting ina break-off as a single blob, depending on plate rheology. Conversely, in models withweaker coupling along the trenches, peelback along the northern slab creates a thinlithosphere along the accretionary prism, such as in the evolution of the EasternAnatolian Plateau. Our results highlight the important interaction between thesubduction systems where rheological constraints of the lithosphere, among othermodel parameters, exert a first-order control for plateau formation.
A Global Collaboration to Enhance GNSS Receiver Antenna Calibration: The IGS Antenna Ring Campaign
Authors: Kersten Tobias , Bilich Andria , Sutyagin Igor , Schön Steffen
Published: March 2024

Achieving a high-precision geodetic spatial reference depends on a thorough understanding of the equipment-specific sources of error of phase centre corrections (PCCs) of Global Navigation Satellite System (GNSS) receiver antennas. GNSS station operators and network analysers are constantly challenged regarding consistent PCCs, such as in the latest IGS Repo3 project. The challenges are, on the one hand, that not for all antennas in the network multi-GNSS calibrations are available. On the other hand, not all antennas are individually calibrated, so that type mean combinations with individual PCCs have to be used.Even small differences between PCCs can significantly affect position accuracy, troposphere modelling, and GNSS time and frequency transfer. Such deviations manifest differently depending on used hardware, software, and data processing approach. A generalised and easily accessible benchmark for assessing the quality of PCCs remains difficult to find. There is a lack of easy-to-apply and common quality assessments of PCCs when comparing individual calibrations versus a type mean and results from the various calibration facilities and calibration methods among each other.In response to this challenge, a global initiative involving nine calibration organisations has launched a comprehensive ring calibration campaign. By sharing six constructionally different antenna samples for calibration and presenting the subsequent results, this collaborative effort aims to enhance (1) the consistency of calibration methods and facilities, (2) develop a validation strategy, and (3) provide insights into the stability of receiver antenna calibrations.This contribution provides an overview of the current status of this campaign, initiated one and a half years ago, outlines the calibration and evaluation concept for carrier phase patterns. First initial results from consulting contributors are presented and the roadmap towards a standardised, robust quality assessment framework for PCCs will be covered.
GHG emissions of agricultural peatlands in the Netherlands.
Authors: van der Velde Ype , Aben Ralf , van de kraats Daniel , van den Berg Merit , Peeters Stijn , Boonman Coline , Boonman Jim , Vriend Bart , Erkens Gilles ,   NOBV Team
Published: March 2024

Peatlands used for intensive daity farming are drained to increase productivity. However, drainage lowers the groundwater table, increases oxygen intrusion, and causes decomposition of the peat soil. This decomposition emits CO2 and is estimated to contribute up to 5% of the Dutch national GHG-emissions. Reducing these emissions requires detailed understanding of the spatial and temporal variability of these emissions and the effects of rewetting measures.Here, we present a unique measurement setup and its results to quantify CO2 emissions of Dutch peatlands. We show the results of more than 30 site years of near continuous CO2 flux measurements with automated chambers across a wide range of peat types and different wetness conditions. We interpret the net yearly CO2 emissions in relation to water management, peat type and profile. We find clear relationships between yearly average groundwater level, the carbon density in the top 30 cm of the peat profiles, and the estimated yearly CO2 emissions from peat decomposition. However, these relationships come with a large variability between sites and between years that requires further attribution to other site characteristics such as management and history. Moreover, we compare our results to previous studies and discuss the differences and similarities.
Are seismic waves robust enough to detect the presence of water in the lower part of the mantle transition zone?
Authors: Mondal Rabindranath , Shukla Gaurav , Chatterjee Swastika
Published: March 2024

The mantle transition zone (MTZ) is known to be potentially hydrated as laboratoryexperiments have shown that the two major mineral phases namely wadsleyite (β-M2SiO4 ;M: Mg, Fe) and ringwoodite (γ-M2SiO4; M: Mg, Fe) can accommodate significant amounts ofwater in the form of hydroxyl ions in their crystal structure. Direct in-situ evidence of theMTZ being (at least locally) hydrated has been derived from natural diamonds containinghydrous ringwoodite inclusions (Pearson 2014, Nature). Hence, in this study, we haveinvestigated the crystal structure and the thermoelastic properties of Fe-bearing ringwooditeas a function of temperature, pressure, and water content (0 wt%, 1.56 wt%, 3.3 wt%) using acombination of first-principles density functional theory (DFT) and quasi-harmonicapproximation (QHA). Our calculation reveals that hydration in general causes a reduction inthe sound wave velocity of ringwoodite. However, the ‘reduction’ brought in by hydration issignificantly suppressed at pressures corresponding to the lower part of the MTZ.Consequently, the sound wave velocities for the 1.56 wt% water-containing ringwooditemodel is found to become very similar to the sound wave velocities of the anhydrousringwoodite. However, when the water concentration is increased further to ~3.3 wt%, the pressure-inducedsuppression at lower MTZ pressures though present is not significant. These findings indicate that though seismicwaves may not be able to precisely decipher the state of hydration of the lower part of MTZwhen the water concentration is less than 1.56 wt%, it is still robust enough to locate regionsof very high water concentration ~ 3.3 wt%.