bluuebunny/crossref_metadata_2025 huggingface dataset:
Nordic Sea convection led abrupt North Atlantic warm events during Dansgaard-Oeschger cycles
Authors: Simon Margit , Muschitiello Francesco , Sadatzki Henrik , Berben Sarah , Friedrich Tobias , Blindheim Dag-Inge , Wacker Lukas , Jansen Eystein , Dokken Trond
Published: March 2024

During the last glacial period changes in the strength of ocean convection in the high-northern latitudes contributed to abrupt global climate changes known as Dansgaard–Oeschger (DO) cycles. However, the lack of high-resolution empirical evidence has yet precluded inferring the physical coupling between ocean and atmosphere. We examined Nordic Sea (NS) circulation changes by reconstructing radiocarbon ventilation ages across four DO cycles in a marine sediment core hinging on a precise multi-tephra-based synchronization to Greenland ice cores. Our results show that open ocean convection in the NS resumed ahead of the abrupt air-temperature increases recorded in ice cores by ∼400 years (95% range: 50-660 years). Thus, implying an active role of ocean dynamics where abrupt warming transitions are likely a nonlinear response to more gradual resumption of NS convection. 
Groundwater changes affect soil CO2 dynamics
Authors: Seeger Stefan , Hayat Faisal , Saeidi Talat , Maier Martin
Published: March 2024

Soils play a central role in the global carbon (C) cycle and can be a major source or sink of greenhouse gases. The highest concentrations and turnover of soil C is typically found in the top soil (0-0.5m depth). Yet, the total amount stored of soil organic carbon (SOC) in the subsoil (e.g. 0.5-3m) can be large and could be mobilized when soil environmental conditions change. These could be slow changes due to global climate change e.g. in subsoil moisture or temperature affecting subsoil respiration, but also more abrupt changes e.g. subsoil SOC mineralization after a decline in the groundwater level when prior submerged SOC gets exposed to higher O2 levels. Our objective was (1) to study the effect of a changing groundwater level on soil CO2 concentration dynamics and (2) to test if the gradient method is a suitable tool to identify subsoil respiration effects.For this pilot study we used a multilevel soil CO2 profile probe that allowed simultaneous online monitoring of soil CO2 concentration at different depth (Osterholt et al 2022), and calculation of the depth distribution of the soil respiration profile based on the gradient method (Maier & Schack-Kirchner, 2014). The CO2 probe and additional sensors were installed in a large (3 m diameter) lysimeter field station with sandy soil where the groundwater table was kept constant for >10 years at 0.8m depth. During the study period the ground water table was changed several times between 0.3-1.0m depth directly inducing effects on the CO2 concentration itself (piston flow) and also on the soil respiration profile (enhanced mineralization after groundwater level drops), which would not have been observed by pure chamber measurements at the surface. Osterholt, L.; Kolbe, S.; Maier, M. (2022): A differential CO2 profile probe approach for field measurements of soil gas transport and soil respiration #. In J. Plant Nutr. Soil Sci. 185 (2), pp. 282–296. DOI: 10.1002/jpln.202100155.Maier, M., & Schack-Kirchner, H. (2014). Using the gradient method to determine soil gas flux: A review. Agricultural and Forest Meteorology, 192–193, 78–95. https://doi.org/10.1016/j.agrformet.2014.03.
First applications of the Rapid Impact Model Emulator
Authors: Byers Edward A. , Werning Michaela , Krey Volker , Riahi Keywan
Published: March 2024

Climate model emulation has long been applied to IAM emissions scenarios, but is typically limited to first-order climate variables like mean air temperature. Recently, approaches have been developed to reproduce a growing number of climate variables, also with spatial, even gridded, resolution, such as the MESMER (Beusch et al., 2020) and STITCHES (Tebaldi et al., 2022) models. Here we demonstrate a recently-released post-processing software package, that takes the global mean surface air temperature trajectory, and calculates a range of climate impacts and exposure indicators (25+) in gridded spatial and tabular formats. The Rapid Impact Model Emulator uses a combination of pattern-scaling and time-sampling approaches and can be used on indicators that have been prepared at global warming levels, such as for hydrology and crop yields.Using a database of such indicators (Werning et al 2023.), including outputs of global climate and hydrological models and a fire weather index, we show how batches of climate indicators can be quickly provided as outputs for new IAM scenarios. Combined with population exposure and vulnerability layers, we present new insights on the climate risk burden of different IPCC scenarios to illustrate how such approaches can bridge the IPCC WGII and WGIII communities, and take us beyond the constraints of RCP pathways.
Pioneering Direct Flux Measurements for Immediate Societal Benefits: Latest Tools, Developments, and Community of Practice
Authors: Burba George , Metzger Stefan , Community CarbonDew
Published: March 2024

The Carbon Dew Community of Practice is an international non-profit representing carbon and climate experts from over 160 organizations. Our vision is to anchor fair and equitable climate solutions in direct atmospheric measurements of GHG transfers to or from the atmosphere. Our mission is to facilitate technology transfer by providing a medium for public and private entities to work together towards common goals. We strive to translate surface-atmosphere science into real-world impacts and innovate industry practices with the best available science. To achieve this, we support the integration and coordination of existing capabilities and resources for enhancing the measurement and quantification of GHG emissions and removals.Initial Endeavors:Formation of a well-rounded community representing all pertinent stakeholders and experts in climate solutions and GHG emissions trading.
Launching collective contributions to workshops and conferences aimed at educating on the significance of direct GHG measurements for equitable climate solutions and emissions trading.
Collaborative creation of responses to government policy and funding proposals, co-authoring publications, and piloting projects to test the efficacy of specific methodologies.
Future phases will involve efforts towards comprehensive recommendations or protocols, ensuring a balance across environmental, economic, financial, and regulatory aspects to achieve practical and fair climate solutions globally.
Key Stakeholders:Natural and managed ecosystems contributing to global-scale carbon sequestration and storage services.
Growers, ranging from small-scale farmers to large farm corporations, with substantial potential for reducing carbon emissions.
Industries across food, oil, and gas sectors, holding significant potential for carbon emission reduction.
Municipalities and local governments empowered to curtail carbon emissions through regulations and community-focused incentives.
For-profit entities like financial consultants, carbon traders, and tech innovators capable of incentivizing emission reduction while generating profits.
National governments and global non-profits serving as regulators and facilitators to drive societal improvements and incentivize emission reduction.
This presentation offers a progress report on the latest available tools and other developments in practical technology transfer of flux tools from academia to wider society, the latest adoption examples from FAO to the oil and gas sector, and a progress report on the latest activities by the CarbonDew Community.
Drought‐Induced Vertical Displacements and Water Loss in the Po River Basin (Northern Italy) From GNSS Measurements
Authors: Pintori Francesco , Serpelloni Enrico
Published: March 2024

Drought is one of the most complex recurring natural disasters, defined by a deficiency of precipitations that causes prolonged water scarcity. Failure to manage drought risk has the potential to have dire consequences for people, livelihoods, economy and ecosystems.In northern Italy, particularly in the highly productive industrial area of the Po river basin, the 2021-2022 period culminated in the most severe drought of the last two centuries.In order to evaluate the best policies to address the problems caused by water scarcity, it is crucial to measure and monitor variations in terrestrial water storage (TWS). For drought monitoring, in fact, changes or anomalies in TWS provide direct observations of total water availability, complementing model-based measures such as drought severity indices.To estimate the quantities and spatial distribution of TWS loss, we analyze vertical ground displacement time-series data from Global Navigation Satellite System (GNSS) stations in the Po river basin. We use a regularization model, based on L1-norm, to reconstruct the long-term temporal evolution of vertical ground displacement trends. Next, we performed a Principal Component Analysis (PCA) on GNSS time series to extract a spatially consistent signal in vertical ground displacements. The temporal evolution of the first principal component is well-correlated with trend changes of the Po river level and with the  SPEI-12 drought index, with stations moving upward during periods of river/index level decrease and vice versa, indicating that common long-term variations in vertical ground displacements are driven by the hydrology of the area.The inversion of the displacements associated with the first principal component allows us to estimate variations in equivalent water height (EWH) and find that between January 2021 and August 2022, the GNSS stations underwent uplift, up to 7 mm, which corresponds to ~70 Gtons of water loss. The results are compared with the Global Land Data Assimilation System (GLDAS) model and the Gravity Recovery and Climate Experiment (GRACE) data: while the temporal evolution of the three products, when averaged over the study area, is similar, the spatial distributions are different. This is likely due to the fact that GLDAS only takes surface water into account, and GRACE has a too-coarse spatio-temporal resolution.Our results show that multi-year changes in water storage can be effectively monitored both in terms of temporal evolution and spatial distribution using space geodetic measurements, such as GNSS. This approach eliminates the need to rely solely on large-scale models or satellite measurements, which cannot reach the spatial resolution required at the scale of river basins such as the Po.
Towards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central IranTowards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central Iran
Authors: Rashidi Koochi Zakieh , Büdel Christian , Torabi Mehdi , Baumhauer Ronald , Fuchs Markus
Published: March 2024

The Great Central Desert of Iran, located at the center of the Iranian plateau, bears valuable but scattered geological and geomorphological archives. However, the scarcity of data on the paleoenvironment and paleolandscape of this area is attributed to challenging accessibility and harsh climatic conditions. The Khur area in the eastern edge of the Iranian Central desert was selected for this investigation due to its distinctive geomorphological features and improved accessibility.This study aims to delineate Late Pleistocene-Holocene landscape evolution in central Iran by utilizing sedimentary and morphostratigraphical evidence of aeolian-fluvial sequences. In a first step, geomorphological features were mapped based on satellite imagery, digital elevation models, geological maps and field observations. Subsequently, localities for excavator sections were deduced from these findings, guaranteeing accessibility and further ensuring their incorporation of anticipated stratigraphic key features, including contact zones of distinct geomorphological environments. Stratigraphic description of the excavated profiles was recorded, and sedimentary logs were drawn.The preliminary results reveal complex interactions of Aeolian, fluvial, and lacustrine morphodynamics during the Late Pleistocene and Holocene. Seven landform groups including aeolian dunes and interdune areas, sandy mud flat, alluvial fans and fluvial plains, dissected fan toe with backward erosional valleys were recognized. Within these, five interfingering sedimentary units were identified based on distinctive geometry and layering and their internal facies distribution: Fluvial flood deposits, well to poorly-sorted alluvial deposits, aeolian sand deposits, fluvially reworked marl (fine-grained mud), paleosol horizons.In summary, repeatedly changed depositional environments and cyclical climatic changes, where dune development took place during phases of increasing aridity, whereas non-aeolian deposition and paleosol formation might have occurred during more humid conditions and more stable paleosurfaces.Luminescence dating, sedimentological and geochemical analyses, will determine climatic cycles, sedimentary environments and landscape evolution history.
Temporal scales of mesoscale eddy-induced horizontal and vertical transport of carbon, heat and oxygen in the Southern Ocean. 
Authors: Salinas-Matus Mariana , Serra Nuno , Chegini Fatemeh , Ilyina Tatiana
Published: March 2024

The Southern Ocean (SO) has been identified as one of the most widespread mesoscale eddy fields observed in the ocean. However, historically in the SO, eddy effects on the carbon cycle have been poorly understood, especially quantitatively, due to sparse observations in the SO and limited computational resources restricting model resolution. Recently, the importance of representing mesoscale eddies in the SO for generating reliable transient simulations and global climate projections has been suggested. This work focuses on comprehending and quantifying the vertical and horizontal eddy-induced transport of carbon, heat, and oxygen in the upper ocean (first 300 m) across time scales ranging from inter-annual to high frequency. It aims to elucidate the impact of these processes on the ocean's uptake of carbon, heat, and oxygen. Studying these three components helps to distinguish  the role of biogeochemical and physical processes, due to the shared and distinct mechanisms that affect them. As the main tool, we used simulations made with the ocean component of the ICON model, coupled with the biogeochemical model HAMOCC. We employed a hierarchy of model resolutions, ranging from eddy-parameterized to eddy-resolved resolutions, to elucidate the role of representing eddies in facilitating/impeding air-sea fluxes.
Valuing Natural Capital in Communities for Health
Authors: O'Keeffe Jimmy , Burke Jolanta , Kaleta Branislav , Campbell Stephen , O'Connell Cathal
Published: March 2024

The natural capital and ecosystem services that we rely on have been severely impacted by changes to our ecological, biogeochemical and climate systems. This has been driven by our lifestyle choices, impacting our water, air and soil quality. Left unchecked, environmental degradation threatens to reverse the benefits created, exacerbating the decline of our critical natural capital resources. Among the many benefits we obtain from the natural environment, human health and wellbeing are among the most important, yet least understood. In Ireland, mental health conditions, including depression and anxiety impact up to 42% of the population. The costs of poor mental health to the economy are estimated to be €11 billion each year. Furthermore, the second leading cause of death in Ireland is circulatory disease, such as heart attack, or stroke. This Science Foundation Ireland funded project VNiC-Health (Valuing Natural Capital in Communities for Health) will focus on providing evidence from both a human health and wellbeing, and a quality natural environment point of view, helping to address two of the most critical challenges affecting society - the climate and environmental emergency, and our health crisis.
Indigenous soil microbial inoculants promote restoration of arid plants in saline soils
Authors: Dadzie Fred , Machado Nathali , Muñoz-Rojas Miriam
Published: March 2024

Salinity is one of the challenges affecting seed germination and establishment in dryland restoration projects. Seeds must overcome the osmotic pressure present in saline soils before they can germinate. An ideal method is to reduce the osmotic potential through continuous irrigation to flush out the excess salts from the soil to enable seeds to germinate. However, such a system is impractical at scale and would exponentially increase restoration budgets. Research has shown that bacteria and cyanobacteria individually improve seedling germination. However, it is unclear whether bacteria and cyanobacteria improve seedling germination individually and as combined entities under dryland conditions. In this glasshouse study, we test the hypothesis that, inoculating seeds with bacteria, cyanobacteria and the combination of both will increase seed germination outcome compared to their none inoculated counterpart. We also examined which microbial inoculation would yield the greatest seedling germination and biomass. We found that all inoculated seeds with microorganisms significantly increased seedling emergence and biomass production compared to the non-inoculated seeds. The highest seedling emergence was found in the cyanobacteria treatment followed by the combined bacteria and cyanobacteria treatment. Similarly, the highest biomass production occurred when seeds were inoculated with cyanobacteria treatment followed by bacteria treatment. Our results suggest that, cyanobacteria can be used as a potential tool to overcome seedling germination challenges in saline dryland ecosystems during restoration.
Satellite optical imagery: towards fully integrated measurements of the coastal zone.
Authors: Bergsma Erwin , Artigues Stephanie , Almar Rafael , Klotz Adrien , Garlan Thierry
Published: March 2024

Space-based coastal observations are emerging as satellite imagery becomes more freely available through large-scale programs such as Landsat and Copernicus. Remote sensing techniques enable large-scale, even global, studies with sufficient spatio-temporal resolution, given that, for example, optical satellite imagery from the Sentinel-2 program has a global coastal coverage of up to 20 km offshore and a revisit of 2 to 5 days. The availability of data combined with accessible tools has enabled an explosion in space-based observations, even if these observations now go beyond the research phase alone and can support large-scale decision-making (see, for example, the Space Climate Observatory). However, most spaceborne applications for the coastal zone focus on useful but indirect proxy indicators such as waterline estimation. Submerged bathymetry and emergent topography are often not taken into account, even though they are essential for the usage and forecasting with of process-based models. Here, we present current work by the French Space Agency in collaboration with LEGOS and Shom on the future of space-based coastal observations: total, fully integrated monitoring of the coastal zone from space. This includes simultaneous measurements of bathymetry, coastline and topography at multiple spatial and temporal scales. Sentinel-2's large-scale bathymetry estimation and coastline detection, complemented by 3D topography using very high-resolution Pleiades images, offer a solution for monitoring the coastal zone from space over large regional scales. All these components of coastal monitoring are open-source, such as the CNES CARS routines for DEM 3D topography estimation, the CNES-IRD-SHOM S2SHORES bathymetry estimation. While focusing on current capabilities, we will also present prospects for future Earth observation missions, such as CO3D, and new capabilities for obtaining fully integrated measurements in a single satellite pass.
Participatory development of indicators to support WEFE Nexus management in the Mediterranean
Authors: Pacetti Tommaso , Merheb Mohammad , Lompi Marco , Schneider Xenia , Cudennec Christophe , Rodriguez-Sinobas Leonor , Bahnassy Mohamed , Abdelli Fethi , Rossetto Rudy , Bresci Elena , Castelli Giulio , El Jeitany Jerome , Lucca Enrico , Caporali Enrica , Nardi Fernando
Published: March 2024

Summarizing the various dimensions of the Water-Energy-Food-Ecosystem (WEFE) Nexus and articulating their interconnections through indicators can improve the understanding of the Nexus among both experts and stakeholders without specialized knowledge, supporting the transition towards implementing a WEFE Nexus approach for effective management of socio-ecological systems. As part of the EU PRIMA-funded project NEXUS-NESS, a participatory approach has been devised for identifying indicators related to the WEFE Nexus. The project's objective is to collaboratively develop WEFE Nexus management strategies within four Living Labs, designated as Nexus Ecosystem Labs (NELs), situated in distinct Mediterranean countries (namely, Egypt, Italy, Spain, and Tunisia). To achieve this, the concept of Responsible Research and Innovation (RRI) has been implemented through the RRI Roadmap (The RRI Roadmap©™ is under the ownership of XPRO Consulting Limited) methodology to establish a stakeholders’ participatory and interactive process. This involves active engagement between societal stakeholders and scientists, fostering knowledge-sharing and co-defining the indicators used to represent the WEFE Nexus within the NELs. Specifically, the work done has led to the formulation of a comprehensive inventory of WEFE Nexus indicators, applicable across all NELs. Additionally, a simplified representation has been developed to provide a preliminary assessment of the Nexus within the NELs under current conditions and future scenarios. Subsequently, a matrix approach has been devised to systematically map and evaluate all interconnections within the WEFE Nexus within a given NEL, utilizing indicators tailored to the specific needs of that NEL and its stakeholders.These indicators will play a crucial role in assessing the advantages and trade-offs associated with proposed solutions to the main Nexus-related challenges identified within the NEL. Furthermore, they will support the cost-benefit analysis, serving as a pivotal element in the identification of the most suitable WEFE Nexus-based management strategies. The methodology can be applied to any waterbody that wishes to develop a WEFE Nexus management strategy and achieve ownership and willingness for change by the waterbody’s stakeholders.
A diminishing stabilizer? Studies on the influence of ice and gas hydrates on the geo-mechanical properties of sediments.
Authors: Spangenberg Erik , Cook Ann , Schicks Judith , Heinig Fabian
Published: March 2024

Natural gas hydrates form at elevated pressure and low temperatures in the presence of sufficient quantities of gas and water and have therefore been discovered on all continental margins and in permafrost regions. In the marine hydrate-bearing sediments, gas hydrates, depending on their content, can transform a loose sediment into a consolidated rock with a strongly increased strength. In permafrost regions the hydrate stability zone can extent deep into the ice-bearing permafrost and, therefore, both, ice and hydrate can consolidate the sediment. However, the strength of methane hydrate is much higher than that of ice, which behaves much more ductile. Consequently, the resulting strength of a sediment, containing both components, strongly depends on the ice to hydrate ratio. Conversely, the decomposition of natural gas hydrates in marine or permafrost sediments leads to a reduction in the mechanical strength of the host sediment. In addition, the release of gas can create overpressure in the pore spaces, reducing the effective stress and leading to instabilities in the sediment structure.Since both continental margins and permafrost regions are used by humans for various activities that largely depend on the mechanical stability of the sediments, knowledge of the main factors and processes that determine the stability of weakly consolidated sediments is crucial. Both the thawing of ice and the decomposition of gas hydrates in permafrost soils lead to a change in the geo-mechanical properties of the host sediment. The residual and peak shear strengths of ice- and hydrate-bearing sediments were investigated using a ring shear cell developed at the GFZ. Based on literature data and our results, we discuss the dependence of the geo-mechanical properties of sediments on ice and hydrate saturation and the possible consequences if their proportion diminishes.
Cloud radar spectral polarimetry for drop-size-distribution profiling: perspectives and challenges
Authors: Myagkov Alexander , Nomokonova Tatiana , Frech Michael
Published: March 2024

Rainfall is a critical component of the Earth's water cycle, influencing global economic stability, access to food and freshwater, and daily life. Rain is also frequently used as a calibration target for various remote-sensing instruments. As such, timely and accurate observations of rainfall are vital for meteorological applications. The microphysical properties of rain are commonly characterized by the drop-size distribution (DSD), which determines the water content, intensity of precipitation, and kinetic energy of the rain.Conventional methods for measuring DSD include in situ instruments such as optical disdrometers and polarimetric weather radars. Disdrometers measure the size and velocity of raindrops within a narrow laser beam, providing data only at the surface level and having uncertainties due to the limited sampling area. Polarimetric weather radars, on the other hand, can observe rain profiles over larger areas, but typically only capture higher moments of the DSD, which then require specialized retrieval methods to derive DSD properties. Such retrievals are typically based on known size-shape-velocity relations for raindrops and a scattering model. Polarimetric variables are of an especial value because they allow to decouple the contribution of shape, size, and concentration of raindrops to the observations. In addition, the polarimetric variables can be accurately calibrated. The results of retrieval based on the moments are, however, prone to uncertainties related to measurement errors and limited information content of the DSD moments.Polarimetric Doppler cloud radars, operating at millimeter wavelengths, offer an alternative to traditional methods of the DSD estimation. They can measure the same set of parameters as weather radars but spectrally resolved, i.e. the cloud radar can separately measure droplets coexisting in the same volume but moving with different velocities relative to the radar. Since velocity of droplets is a proxy of their size, spectrally resolved measurements contain much more information about the underlying DSD.This study explores the potential of polarimetric cloud radars to retrieve DSD profiles. We highlight the advantages of this approach, including the ability of the non-parametric estimation of DSD profiles. We also examine existing challenges, such as the impact of resonance effects on observations due to the comparable wavelength of cloud radars and droplet sizes. These effects require accurate representation in scattering models and size-shape-velocity relationships. Current literature lacks explanations for some observations, indicating a need for further research and development of retrieval methods based on spectral polarimetric cloud radar data.
Physics-Informed Ensemble Surrogate Modeling of Advective-Dispersive Transport Coupled with Film Intraparticle Pore Diffusion Model for Column Leaching Test
Authors: Ershadi Amirhossein , Finkel Michael , Liu Binlong , Cirpka Olaf , Grathwohl Peter
Published: March 2024

Column leaching tests are a common approach for evaluating the leaching behavior of contaminated soil and waste materials, which are often reused for various construction purposes. The observed breakthrough curves of the contaminants are affected by the intricate dynamics of solute transport, inter-phase mass transfer, and dispersion. Disentangling these interactions requires numerical models. However, inverse modeling and parameter sensitivity analysis are often time-consuming, especially when sorption/desorption kinetics are explicitly described by intra-particle diffusion, requiring the discretization along the column axis and inside the grains. To replace such computationally expensive models, we developed a machine-learning based surrogate model employing two disparate ensemble methods (stacking and weighted distance average) within the defined parameter range based on the German standard for column leaching tests. To optimize the surrogate model, adaptive sampling methods based on three distinct infill criteria are employed. These criteria include maximizing expected improvement, the Mahalanobis distance (exploitation), and maximizing standard deviation (exploration).The stacking surrogate model makes use of extremely randomized trees and random forest as base- and meta-model. The model shows a very good performance in emulating the behavior of the original numerical model (Relative Root Mean Squared Error = 0.09). Our proposed surrogate model has been applied to estimate the complete posterior parameter distribution using Markov Chain Monte Carlo simulation. The impact of individual input parameters on the predictions generated by the surrogate model was analyzed using SHapley Additive exPlanations methods.
The coevolution of life and landscape in the Atacama Desert
Authors: Binnie Ariane , Lampert Kathrin , Victor Pia , Reicherter Klaus , Vega Ruiz Ambrosio , Evenstar Laura , González Gabriel , Binnie Steven
Published: March 2024

The evolution of landscapes has often been inferred from the phylogenetic records of species that inhabit them, but it is rare to have a sufficiently detailed record of landscape evolution to be able to test the validity of links between bio- and geochronometers. Here we derive the history of fluvial incision of the Tiliviche River in the Central Depression of the northern Atacama Desert, Chile, using cosmogenic nuclide exposure dating of fluvial terraces and nearby paleochannels. We compare this to the timing of speciation from molecular clock dating of Ephemeroptera (Mayflies), collected from both the Tiliviche and proximal Camerones Rivers. Both these drainages source their discharge in the Western Cordillera of the Andes Mountains and drain westwards to the Pacific Ocean. Where they pass through the low relief Central Depression between the Andes and Coastal Cordillera they have formed steeply incised canyons. Our exposure dating shows that notable incision of the Tiliviche River into the Central Depression began around 2 Myr ago. The timing of the divergence of Ephemeroptera species from the Tiliviche and Camerones Rivers is coeval with the onset of Tiliviche incision at 2 Myr. Furthermore, this history of river incision and speciation is consistent with the timing of abandonment of smaller streams that used to flow across the pampa between the Tiliviche and Camerones rivers (Binnie et al., 2020).  Our results imply that the downcutting of the Tiliviche as a deep canyon and the contemporaneous drying out of smaller drainages between Tiliviche and Camerones were sufficient to isolate the Ephemeroptera clades.  This provides a positive test of a coupled bio- geochronometer approach for unravelling relationships between life and landscape. Whether the controls of river incision and consequently speciation are predominantly climatic, tectonic, or autogenous in nature is still to be resolved.Binnie S. A, Reicherter K. R., Victor P., González G., Binnie A., Niemann K., Stuart F.M., Lenting C., Heinze S., Freeman S.P.H.T. and Dunai T. J. (2020)The origins and implications of paleochannels in hyperarid, tectonically active regions: The northern Atacama Desert, Chile. Global and Planetary Change, Volume 185. https://doi.org/10.1016/j.gloplacha.2019.103083
Variability of the Barents-Kara Sea Sea Ice Area and its Correlation with Atlantic Water Recirculation through the Barents Sea Opening
Authors: Heukamp Finn , Wekerle Claudia
Published: March 2024

In this study, we investigate the interannual variability of the sea ice area (SIA) in the Barents-Kara Sea (BKS) region. We explore the contributing factors to this variability, primarily focusing on oceanic influences evident in the Barents Sea Opening (BSO). The BSO, characterized by eastward warm Atlantic Water (AW) inflow, plays a crucial role in shaping the BKS SIA. While the inflow has been extensively studied, the westward-directed outflow known as Bear Island Slope Current (BISC), remains insufficiently observed. Being fed by relatively warm recirculating modified AW (mAW), the BISCs impact on the overall ocean heat transport (OHT) variability is uncertain. Utilizing the global Finite Volume Sea Ice and Ocean Model (FESOM2.1), we derive estimates of the interannual volume transport and temperature variability of the BISC, filling the observational gap. We find that whereas the variability of BSO inflow/BISC volume transport is similar in magnitude, the temperature variability of the BISC exceeds the BSO inflow temperature variability. By linking the simulated BISC variability to BKS SIA, our findings reveal a yet unknown, strong co-variation between the volume transport of the BISC and the BKS SIA at the end of the freezing season, with a short lead time of zero to three months. We thus further examine the role of the BISC in generating interannual anomalies in the BKS SIA. Our model simulations illustrate that the volume transport of the BISC can be modified by the emergence of a secondary mAW recirculation downstream the northern AW path through the BS in the months preceding anomalously large BKS SIA. This secondary mAW recirculation is thereby increasing the volume transport of mAW leaving the BS via the BISC, reducing the amount of AW reaching the northern Barents Sea ice edge downstream. Additionally, we identify a connection between the atmospheric forcing pattern associated with the volume transport variability of the BISC and anomalous sea ice advection into the BKS as a second cause for the BISC volume transport/BKS SIA co-variability.In general, our study emphasizes the co-variability between BKS SIA and the BISC. We highlight the role of the mAW recirculations in altering the amount of AW, and consequently ocean heat, reaching the ice edge in the northwestern Barents Sea.
Improved Monitoring of Subglacial Lake Activity in Greenland using CryoSat-2 swath processed data and TanDEM-X DEMs. 
Authors: Sandberg Sørensen Louise , Simonsen Sebastian , Havelund Andersen Natalia , Bahbah Rasmus , Karlsson Nanna , Solgaard Anne , Leeson Amber , Maddalena Jennifer , McMillan Malcolm , Bowling Jade , Gourmelen Noel , Horton Alex , Wessel Birgit
Published: March 2024

Subglacial lakes form beneath ice sheets and ice caps if water is available, and if bedrock and surface topography are able to retain the water. On a regional scale, the lakes modulate the timing and rate of freshwater flow through the subglacial system to the ocean by acting as reservoirs. More than one hundred hydrologically active subglacial lakes, that drain and recharge periodically, have been documented under the Antarctic Ice Sheet, while only approximately 20 active lakes have been identified in Greenland. Active lakes may be identified by local changes in ice topography caused by drainage or recharge of the lake beneath the ice. The small size of the Greenlandic subglacial lakes puts additional demands on mapping capabilities to resolve the evolving surface topography in sufficient detail to record their temporal behavior. Here, we explore the potential for using CryoSat-2 swath-processed data together with TanDEM-X digital elevation models to improve the monitoring capabilities of active subglacial lakes in Greenland. We focus on four subglacial lakes previously described in the literature, and combine the new data with ArcticDEMs to obtain improved measurements of the evolution of these four lakes.We find that with careful tuning of the swath-processor and filtering of the output data, the inclusion of these new data together with the TanDEM-X data provides important information on lake activity, documenting, for example, that the ice surface collapse basin on Flade Isblink Ice Cap was 30 meters deeper than previously recorded. 
Fine sediment in mixed sand-silt environments impact bedform geometry by altering sediment mobility
Authors: Hoitink Antonius , de Lange Sjoukje , Niesten Iris , van Veen Sanne , Lammers Jasper , Waldschlager Kryss , Baas Jaco , Boelee David
Published: March 2024

The geometrical characteristics of subaqueous dunes may exert a strong control on hydraulic roughness. Conventionally, the prediction of dune existence and geometry relies on phase diagrams and empirical equations tailored for uniform, cohesionless sediments. However, in deltas, estuaries, and lowland rivers, mixtures of sand, silt, and clay are prevalent, which hamper dune prediction. We study the impact of fine sand-silt mixtures on the geometry of dunes. We built a sediment recirculation facility in the Water and Sediment Laboratory at Wageningen University, capable of recirculating mixtures of sediment. The system is composed of a 15-m long tilting flume and a low reservoir where sediment is kept in suspension using a caterpillar system, from where sediment is pumped back into the flume. We systematically varied the sand and silt content for different flow rates. We measured flow velocities profiles with an acoustic Doppler velocimeter (UB-Lab 2C by Ubertone), and captured the bed geometry using a line laser scanner. The mobility of the bed is clearly influenced by the bimodal characteristics and the level of cohesion. When non-cohesive fine sand or coarse silt were introduced to medium-sand base material, we infer that the hiding-exposure effect amplified the mobility of the coarser material. This resulted in increased dune lengths, affecting dune steepness. Conversely, the addition of weakly cohesive fine silt reduced sediment mobility and suppressed dune length. As a consequence, sediment composition has an indirect influence on hydraulic roughness, which was significantly related to leeside angle. During the high flow rates, our results suggest flickering between alternative stable river bed states.
Assessing the variability of 40K measurements using a portable gamma-ray spectroscopy in an irrigated agricultural field (Spain)
Authors: Catalá Arturo , Navas Ana , Gaspar Leticia
Published: March 2024

Understanding the temporal and spatial distribution of soil water content (SWC) is critical for efficient water resource management in agriculture. However, the variability of SWC over time and space presents challenges in obtaining accurate values at field scale using conventional methods. Proximal gamma-ray spectroscopy (PGRS), supported by adequate calibration and biomass corrections, emerge as promising methods for monitoring SWC. The inverse correlation between the gamma counts of the radioisotope 40K (1461 KeV) and volumetric SWC (m3/m3) demonstrates potential for reliable soil moisture estimation in agricultural and hydrological applications. This contribution examines the potential application of a portable sodium iodide (NaI) scintillation detector (PGRS) for estimating SWC in an irrigated wheat field. We explore the sensitivity of the 40K variations to changes in soil moisture and detector height. Over the last two months of the growing season, several one-hour manual monitoring surveys were conducted to capture the effect on 40K signal of irrigation and soil moisture status before and after the harvesting. In each survey, total counts of 40K were recorded using a NaI detector positioned at different elevations above the ground in the middle of a wheat field. Preliminary results indicate a general correlation between 40K (cps) and SWC throughout the study period, suggesting the sensitivity of the PGRS detector to SWC variations. Our findings show a slight increase in 40K counts by decreasing the detector height for all the field surveys conducted. In addition, we observed that the lowest counts of 40K were recorded during the survey with the highest soil water content after irrigation. We can conclude that 40K signal is sensitive to both changes in SWC and the height position of the detector. Furthermore, this detector offers a significant advantage, as it not only captures data on the 40K peak but also analyses the full gamma spectrum.
Ediacaran ultra-weak geomagnetic field, oxygen rise, and the diversification of macroscopic animals
Authors: Cottrell Rory , Tarduno John , Huang Wentao , Xiao Shuhai , Blackman Eric , Zhou Tinghong , Schneider Jack , Bono Richard , Ibañez-Mejia Mauricio
Published: March 2024

A major discovery in the last 5 years has been the recognition that the geomagnetic field was at ultralow field strengths, some ten times weaker than the present-day, during the Ediacaran Period. These ultralow values were first reported from single crystal paleointensity analyses of 565 Ma rocks of the Sept Îles Mafic Intrusion Suite (Bono et al., Nature Geosci., 2019), and were later confirmed by studies of dikes and lavas from other sites in Ukraine and Canada (e.g., Thallner et al., EPSL, 2021). The ultralow values are followed by a rapid increase in field strength in the early Cambrian (Zhou et al., Nature Commun., 2022) and together these signals are consistent with initial nucleation of Earth’s inner core, as predicted by thermal models and geodynamo simulations (Davies et al., GJI, 2022). An updated timeline incorporating new paleointensity data from several localities in North America, South America and Africa highlights a striking temporal correspondence between the ultralow field, the Ediacaran diversification of macroscopic animals, and some geochemical indicators for the rise of oxygenation. The onset of inner core growth and unusual state of the geomagnetic field should not correspond with animal evolution or oxygenation unless changes in the Ediacaran magnetosphere attendant with the ultralow field somehow affected the atmosphere, oceans and/or biosphere. We will consider these possibilities. 
Impact of Marine Heatwaves over the water column in a coastal ocean: a case study in the Bay of Biscay and the English Channel 
Authors: Charria Guillaume , Poppeschi Coline , Simon Amélie , Gaymard Anne , Martinez Almoyna Carlhand Maud , Savoye Nicolas , Lienart Camilla , Ulses Caroline , Pairaud Ivane , Couvelard Xavier , Theetten Sébastien , Le Roux Jean-François
Published: March 2024

Coastal ecosystems are under climate and anthropogenic pressures. Extreme events as Marine Heatwaves (MHW) directly impact environmental conditions necessary to sustain biodiversity in coastal oceans. Recent results showed increasing occurrence and intensity of MHW in the Bay of Biscay and the English Channel based on surface temperature observations.Combining satellite and in situ observations with recent high resolution numerical simulations, the impact of MHW on the whole water column is investigated to evaluate potential impacts on pelagic and benthic ecosystems. Special attention is given to the last two years, 2022 and 2023, as unprecedent warm years.The last two decades have been observed (in situ and from satellites) and simulated (using CROCO coastal ocean model with 1km resolution) allowing to identify and characterize MHW (occurrence, duration, intensity). The propagation in the water column of observed heating is investigated with regard to the local dynamics (e.g. tides, constrained shallow waters, river plume dynamics). Depending on hydrodynamical conditions, impacts of MHW on the water column are contrasted and sensitive to characteristics from this type of extreme events.Those first results are designed to pave the way for an assessment of the MHW impact on the coastal ecosystem during the last two decades with a focus on 2022 and 2023.
Challenges and Opportunities in the Detection of Trends in Subdaily Heavy Precipitation in the United States
Authors: Mascaro Giuseppe , Farris Stefano , Deidda Roberto
Published: March 2024

Increasing empirical evidence has been showing that, over the last decades, the frequency of daily heavy precipitation has risen in some regions of the United States (U.S.); less evidence has instead been presented at subdaily resolutions. In this study, we describe the challenges and opportunities associated with the detection of trends in subdaily heavy P in the U.S. using Version 2 of the Hourly Precipitation Data (HPD) from the National Climatic Data Center (NCDC). This dataset comprises records from 1897 gages which we found to be affected by several issues preventing their use in trend studies, including long periods with missing observations, changes of instruments, and different signal resolutions (largely, 0.254 and 2.54 mm). Despite this, after proper checks, we were able to identify 370 gages with ≥40 years of statistically homogenous data in 1950-2010 that cover the U.S. with a good density. To improve the ability to detect trends, we designed a framework that quantifies the degree to which the observed over-threshold series above a given empirical q-quantile are consistent with stationary count time series with the same marginal distribution and serial correlation structure as the observations. We also applied the false discovery rate test to account for spatial dependence and multiplicity of the local tests. Analyses were performed for the signals aggregated at Δt = 1, 2, 3, 6, 12, and 24 h and for q = 0.95, 0.97, and 0.99, finding that most gages exhibit increasing trends across all Δt’s and that their statistical significance increases with Δt and decreases with q, but only for Δt ≥ 2 h. This might indicate that the physical generating mechanisms of precipitation have changed in a way that leads to larger accumulations over durations >1 h but similar intensities within 1 h. An alternative possible explanation for these outcomes is instead that the coarse signal resolution (2.54 mm) reduces the power of the test for trend detection as Δt decreases. Investigating these issues will be the subject of our immediate future work.
Compound variation in freeze-thaw index and wind climatic erosivity in the agro-pastoral ecotone in northern China 
Authors: Yang Wenqian
Published: March 2024

Changes in wind speed and temperature significantly co-alter soil erosion climatic erosivity. However, knowledge on compound climatic elements of soil erosion to climate change is limited. Here, we quantify long-term climatic erosivity based on the wind erosion climatic erovisity and freeze-thaw climatic index, and analyze the contributions of single and compound factors using the slope change ratio of accumulative quantity methods. Our results show frequency of compound events is gradually decreasing as a result of climate change. Compound climatic erosivity exhibits large spatial variability and decreases with the wind erosion climatic erosivity and freeze-thaw climatic index. Moreover, a negative temporal trend of compound climatic erosivity is found in 61.28% of the study area from 1981 to 2020, which is largely attributed to declining wind speed. One unanticipated finding was that the frequency of compound erosion has shown a decreasing trend at some sites, but the intensity has shown an increasing trend. A possible explanation for this might be the extreme wind speeds and temperatures. Our findings highlight compounding effects of climatic conditions have a more severe impact on soil erosion.