bluuebunny/crossref_metadata_2025 huggingface dataset:
The redox state of the Earth’s lower mantle: combined evidence from natural mineral inclusions in superdeep diamonds and experimental predictions 
Authors: Stagno Vincenzo , McCammon Catherine , Kaminsky Felix , Marras Giulia
Published: March 2024

The redox state of the Earth’s interior (i.e., the oxygen fugacity, fo2) is related to the Fe speciation (Fe2+, Fe3+) in mantle rock-forming minerals and controls the speciation of volatiles like carbon at depth. To date, the fo2 of the lower mantle has been mostly constrained by HP-T experiments, due to the extreme rarity of natural samples represented by mineral inclusions in sub-lithospheric diamonds. Experimental evidence suggests that the lower mantle is reduced and saturated in Fe(-Ni) metal (about 1 wt%). However, coexisting minerals like ferropericlase and bridgmanite are predicted to contain 0.02 and 0.6 of Fe3+ /∑Fe, respectively. A slight increase of Fe3+ /∑Fe (less than 1 wt%) is expected in the case of fo2 > iron-wüstite buffer. This would imply the complete oxidation of Fe(Ni) alloys promoted by reduction of carbonates (either fluids or melts). The finding of carbonates trapped in sub-lithospheric diamonds is natural evidence of the (local) oxidative redox state of the deep and inaccessible lower mantle and this is enhanced by the lack of metallic inclusions coexisting with Fe3+-poor ferropericlase in sublithospheric diamonds. Moreover, the variation of Fe3+ in bridgmanite appears, at least currently, to be better explained by its crystal chemistry while the effect of pressure and fo2 remains unclear, mainly due to the lack of oxybarometers applicable to lower mantle assemblages.In this study, we combined an experimental investigation of the Fe3+/∑Fe in ferropericlase and bridgmanite equilibrated at known high pressure, temperature and oxygen fugacity conditions with Fe3+ /∑Fe measurements conducted on bridgmanite(-like) and ferropericlase inclusions in sublithospheric diamonds from Rio Sorriso and São Luís (Brazil) and Kankan (Guinea). Some inclusions are composite for which the Fe3+/∑Fe was determined by in situ synchrotron Mössbauer source spectroscopy and the bulk Fe3+ /∑Fe determined.Our preliminary results show a discrepancy between natural inclusions and experimental products in terms of i) modal abundance of ferropericlase and bridgmanite, likely related to their diverse role in diamond formation (redox) processes; ii) chemical compositions expected for both peridotitic and metabasaltic parageneses; and iii) Fe3+ /∑Fe content.
Fast data-driven reduced order models for emulating physics-based flexible mesh coastal-ocean models 
Authors: Mariegaard Jesper Sandvig , Larsen Emil Siim , Engsig-Karup Allan Peter
Published: March 2024

Physics-based coastal ocean models provide vital insights into local and regional coastal dynamics but require significant computational resources to solve numerically. In this work, we develop data-driven reduced order models (ROMs) using machine learning techniques to emulate a 2D flexible mesh hydrodynamic model of Øresund, the Straight between Denmark and Sweden, achieving orders of magnitude speedup while retaining good accuracy. This Øresund model has complex spatio-temporal dynamics driven by time-varying boundary conditions. Two different approaches to generate ROMs offline are developed and compared. Our objective is to assess the advantage of generating such models offline to enable real-time analysis in the online setting.The first approach extracts patterns in space and time using principal component analysis and learn mappings from previous states and boundary conditions to future states using gradient boosting. The second approach employs Dynamic Mode Decomposition with control (DMDc) to account for boundary forcing. The reduced models are trained offline on a part of the available 12 months of 30-minute resolution snapshots of surface elevation, and u- and v-components of the depth-averaged currents. In both cases a very low number O(100) of latent space dimensions are necessary to get accurate results at the order of 2-4 cm RMSE compared to the full high-fidelity model.The emulators provide state estimates online in seconds rather than hours, enabling new applications like uncertainty quantification, data assimilation and parameter optimization that require fast model evaluations. Further developments could look to condition the ROMs on a wider range of potential boundary forcings for scenario exploration. This demonstrates machine learning's potential for accelerating coastal simulations for real-time decision support and planning systems facing long-term change and uncertainty.
Monitoring 3D soil moisture dynamics at a karst forest site with OhmPi, an open source resistivity meter
Authors: Watlet Arnaud , Kaufmann Olivier , Mahieu Anthony , Imig Arnold-Fred , Guyard Hélène , Goderniaux Pascal , Forquet Nicolas , Fargier Yannick , Dubois Vivien , Blanchy Guillaume , Clément Rémi
Published: March 2024

Karst aquifers are particularly vulnerable to changes in environmental factors such as climate change or pollutants. In the critical zone, the role of the superficial layer, the soil and the so-called epikarst, is crucial as it can delay water infiltration and host temporary perched water reservoirs, due to high contrasts in hydraulic conductivity with deeper layers. In an effort to better characterise the effect of the plant activity on the water content in the shallow subsurface, we have designed a time-lapse ERT experiment at the Rochefort Cave Observatory (Belgium). We present results from (at least) 6 months of daily 3D ERT measurements on 64 electrodes installed in a 40x60 cm grid covering a 6.0 x 1.8 m surface area centred on a young beech tree. The ERT dataset is supported by data from a vertical profile of soil moisture probes and in-cave water percolation gauges. Our study also includes an artificial drying and sprinkling experiment which main purposes are to replicate extreme weather events and investigate their effect on the soil moisture condition.This experiment also serves as a testbed for using OhmPi as a monitoring tool in the field. OhmPi is an open-source, open-hardware resistivity meter, which runs on a Raspberry Pi. It is designed for enabling flexible data acquisition, and is primarily dedicated to the research community. Relying on low-cost components and devices, and using a low-power injection module (0-50V), OhmPi is particularly suited for small-scale field and laboratory experiments.
Reducing Excess Nitrogen Through Sustainable Farming Systems in Danish Agricultural Catchments
Authors: Aderele Meshach Ojo , Rahimi Jaber , Butterbach-bahl Klaus
Published: March 2024

Nitrogen pollution from livestock manure has emerged as an escalating global concern. Therefore, it is imperative to evaluate the cropping system that will facilitate the optimal utilization of livestock manure while minimizing the environmental impact. In the quest for sustainable agricultural practices, the incorporation of crop residues into soils and intercropping with catch crops, has been identified as promising strategies. Crop residue incorporation is a carbon farming practice that can have significant implications for both soil organic carbon (SOC) and nitrous oxide (N2O) emissions, while catch crops have been an essential tool for reducing nitrogen leaching.This study uses the process-based biogeochemical model LandscapeDNDC to assess the environmental performance of different cropping systems in six representative Danish agricultural catchments (LOOPs). Generally, two fertilization strategies were distinguished: 1) fields receiving only a mixture of pig and cattle slurry (O-fields), and 2) fields (C-fields) receiving mineral fertilizer.We tested eight scenarios of organic or conventional fertilized fields with or without crop residue incorporation and with or without catch crop (C/O ± CR ± CC)The results revealed that organic fields demonstrated not only lower yield-scaled total emissions compared to conventional fields but also shows benefits in terms of net carbon balance. It therefore indicates that organic farming, especially when combined with crop residue and catch crop may lead to reduced nitrogen-related environmental impact while increasing yield.
Passive characterization of aquifer permeability and shear modulus and their evolution following earthquakes using tidal signals
Authors: Thomas Augustin , Fortin Jerome , Vittecoq Benoit , Violette Sophie
Published: March 2024

Tidal analysis of borehole pressure has become in the recent years’ literature an essential method to follow the evolution of the hydraulic conductivity of an aquifer over time. Most traditional methods (mainly pumping or slug tests) only produce a small number of observations, and come at a greater cost. However, groundwater level tidal analysis only requires monitoring data at a sampling rate of 1 hour, data which is extensively available. These solutions are applicable provided aquifers respond to at least one tidal phenomenon among oceanic, earth or atmospheric tides.Martinique Island, in the Lesser Antilles, is a very interesting field to study these techniques, since 16 years of piezometric level data have been recorded on this volcanic island in a monitoring network of 29 boreholes. Here we focus our study on a closely monitored study site in the Galion plain, with three boreholes, a seismometer and past conducted pumping tests and seismic surveys. We compute amplitude and phase response of aquifers to atmospheric and earth tides. Then, the response of the semi-confined aquifers to different loading sources at the tidal frequencies (between 1 and 2 cycles per day) is modelled. A careful inversion is done to obtain the characteristics of the aquifer, including aquifer transmissivity and shear modulus.Finally, we analyse the evolutions of these inverted parameters and decipher their reversible and irreversible changes. Between earthquakes, we show the dominant effect of effective stress to control aquifer hydraulic conductivity. At the time of the earthquake, with the help of seismic stress numerical simulation, we show that seismic shear stresses are the most probable cause of aquifer properties changes both in permeability and shear modulus.
Vegetation Scenarios to Improve the Conditions at the Desiccated Aral Seabed and to Reduce the Impacts of Sand and Dust Storms
Authors: Haddad Mira , Akramkhanov Akmal , Worqlul Abeyou , Strohmeier Stefan , de Jong Steven , Zakhadullaev Abduvokhid , A. Chaniotis Ioannis , Patlakas Platon , Stathopoulos Christos
Published: March 2024

Although Central Asia has been exposed to sand and dust storms (SDS) due to the Kyzylkum and Karakum deserts, it is also the place of a most tragic environmental disaster of the 20th century: the drying out of the Aral Sea created the Aralkum desert that is considered a relatively new addition to the global hotspot SDS sources. The loss of Aral Sea transformed the surrounding environment into a vast area of bare land dominated by solonchak soils prone to further degradation and desertification. Consequently, the exposed saline sediments have become SDS sources across the region, causing negative impacts on multiple socio-ecological aspects. Recently, the government of Uzbekistan launched and further investigated various campaigns on planting adapted shrub and tree species to establish a robust rangeland ecosystem.This study aims to determine the effects of the vegetation-based options on protecting the erodible sediments from wind-induced movement and improving the local ecological conditions. Wind erosion depends on soil erodibility, selected plant species for out-planting, and vegetation cover succession that might develop. This study developed six vegetation cover scenarios to represent a broad spectrum of potential vegetation cover and stages, ranging from a bare surface (newly dried seabed) to dense vegetation cover conditions. Local 3-hourly wind speed data of the past 20 years was analyzed to define erosive wind events. Each vegetation cover scenario was used in the wind erosion simulation model to assess the impact of different covers on soil erosion.The simulation of the physical-based erosion model revealed critical wind speed thresholds of erosion initiation that most likely occur when wind velocities exceed 10-15 m/s. The erosion ranges linked to the exceedance of three hourly wind speeds of >= 15 m/s (class 1), >= 20 m/s (class 2), and >= 25 m/s (class 3), respectively, were investigated for the six clearly defined vegetation scenarios. The simulation unveils that dense vegetation covers of assorted trees, shrubs, and grasses could ultimately stop erosion, as locally verified through observations in scattered and well protected well-vegetated areas. A more likely and large coverage of a lower-density vegetation could reduce erosion by around 40%. Combining shrubs and potentially emerging grasses would reduce wind erosion by up to 70%.The study indicates that plantation and increasing vegetation cover could remarkably enhance SDS prevention. In addition, it would improve the local ecosystem services such as e.g. storing carbon and serving as potential feed sources for livestock, while preventing contaminated and saline dust from being transported to vulnerable off-site areas.
Tsunami source reconstructed from runup time-series
Authors: Didenkulova Ira , Angeli Cesare , Armigliato Alberto , Pelinovsky Efim
Published: March 2024

The study of long wave runup is a classical problem in fluid dynamics, in both linear and nonlinear formulations. However, little attention has been given to the inverse problem, i.e. the reconstruction of the initial condition from a known runup time history.According to the piston model of tsunami generation, the problem can be modelled as an initial value problem with assigned initial water surface displacement and zero velocity. In this framework, the solution of the linear problem, i.e. the runup as a function of time, can be written as the convolution of the initial water surface with an Abel kernel. This solution can be analytically and uniquely inverted, obtaining the initial wave surface as a functional of the runup function.In this work, this solution is applied to analytically generated runup time series and its properties are analyzed. In particular, the robustness of the solution to added noise is verified and the effect of nonlinearity is investigated through the use of a Riemann transform of the coordinates.
High spatiotemporal reconstruction of Arctic sea ice concentration based on multi-source remote sensing data
Authors: Qiu Yubao , Li Yang , Yu Shuwen , Jin Zekai
Published: March 2024

Sea ice plays a significant role in Arctic research and operations. However, the lack of high spatiotemporal resolution observations on sea ice makes it challenging to accurately depict short-term sea ice changes. This limitation hampers the development of small-scale sea ice change studies and increases uncertainties in Arctic research and operational safety. With advancements in deep learning techniques and the abundance of multi-source remote sensing data such as optical, radar, and passive microwave, reconstructing high spatiotemporal resolution sea ice concentration in the Arctic becomes feasible. Based on multi-source remote sensing data and the integration of sea ice dynamics and thermodynamics, this study proposes a novel deep learning model for high spatiotemporal resolution sea ice concentration reconstruction. Based on this model, we achieved sub-kilometer scale and hourly-level reconstructions of Arctic sea ice concentration from 2021 to 2022, with a mean absolute error of less than 5%, thereby providing data support for Arctic research and operations.
The exceptional winter flood of Loire river 2021: an unexpected source of methane in the inner estuary
Authors: Metzger Edouard , Bombled Bruno , Hulot Vivien , Maillet Grégoire , Mouret Aurélia , Fleurant Cyril , Deflandre Bruno , Rigaud Sylvain , Thibault de Chanvalon Aubin , Sanchez Sophie , Beneteau Eric , Poprawski Yohann , Rabouille Christophe
Published: March 2024

Particles generating Maximum Turbidity Zones (MTZ), in estuaries undergo several cycles of deposition/resuspension cycles before definitive burial or expelling towards the continental shelf. Positioning and spatial coverage depend on its morphology, riverine discharge and tidal dynamics. In the Loire estuary, the decadal flood of February 2021 displaced a lot of material from the upper to the lower estuary. Consequently, cores sampled at four sites upstream Paimboeuf (15 km from estuarine mouth) showed very dark cohesive sediments while those taken at two stations downstream, within the MTZ, showed a thick (10-50 cm), unconsolidated layer of a light-brown sediment over a darker-cohesive one. More striking, these four upstream stations, covering a river line of some 40 km, showed gas ebullition generating numerous cracks on the first decimetres of interface cores.A few months later (June 2021), interface and long cores were sampled and methane analysed at three stations along the salinity gradient (two upstream and one downstream of Paimboeuf). Upstream, the entire interface and long cores showed methane saturated samples (about 2 mmol L-1) and cracks remained ebullitive. Near Paimboeuf, the cores were no longer ebullitive and a clear sulphate-methane transition zone (SMTZ) was observed at 50 cm depth. Downstream, the SMTZ was located at 30 cm depth. These results suggest that the important currents induced by the 2021 winter flood eroded a significant layer of sediment to generate depressurization and allow methane to escape in the upper estuary while the lower estuary remained capped by enough sediment to maintain the SMTZ. They also showed that the decrease of riverine discharge allowed the MTZ to migrate upstream stopping methane to escape in the mid estuary while the upper estuary continued to release methane through ebullition four months after the erosion event. Crack formation and methane release also affected benthic fluxes, increasing total oxygen uptake by a factor of ten (94 mmol m-2 d-1) compared to diffusive flux, for example.The rare opportunity to document such processes because of extreme navigation conditions, particularly for the deployment of the corer, allows us to emphasize that winter flooding can be an important source of methane that is immediately transferred to the atmosphere due to shallow depth of estuaries and must be taken into consideration for budgets and fluxes between reservoirs. This process must also be taken into account for a better understanding of other estuarine biogeochemical cycles, such as oxygen and nutrient cycles, as crack formation and methane release significantly increase their benthic fluxes.
Estimating global POC fluxes using ML and data fusion on heterogeneous and sparse in situ observations
Authors: Navaneethanathan Abhiraami , Cael Bb , Luo Chunbo , Challenor Peter , Martin Adrian , Leonelli Sabina
Published: March 2024

The ocean biological carbon pump, a significant set of processes in the global carbon cycle, drives the sinking of particulate organic carbon (POC) towards the deep ocean. Global estimates of POC fluxes and an improved understanding of how environmental factors influence organic ocean carbon transport can help quantify how much carbon is sequestered in the ocean and how this can change in different environmental conditions, in addition to improving global carbon and marine ecosystem models. POC fluxes can be derived from observations taken by a variety of in situ instruments such as sediment traps, 234-Thorium tracers and Underwater Vision Profilers. However, the manual and time-consuming nature of data collection leads to limitations of spatial data sparsity on a global scale, resulting in large estimate uncertainties in under-sampled regions.This research takes an observation-driven approach with machine learning and statistical models trained to estimate POC fluxes on a global scale using the in situ observations and well-sampled environmental driver datasets, such as temperature and nutrient concentrations. This approach holds two main benefits: 1) the ability to fill observational gaps on both a spatial and temporal scale and 2) the opportunity to interpret the importance of each environmental factor for estimating POC fluxes, and therefore exposing their relationship to organic carbon transport processes. The models built include random forests, neural networks and Bayesian hierarchical models, where their global POC flux estimates, feature importance and model performances are studied and compared. Additionally, this research explores the use of data fusion methods to combine all three heterogeneous in situ POC flux data sources to achieve improved accuracy and better-informed inferences about organic carbon transport than what is possible using a single data source. By treating the heterogeneous data sources differently, accounting for their biases, and introducing domain knowledge into the models, our data fusion method can not only harness the information from all three data sources, but also gives insights into their key differences.
A data-driven approach to predict water security and societal impacts: the risk of drought-induced internal displacement in the Horn of Africa.
Authors: Wens Marthe , de Moel Hans , van Loon Anne , Isabellon Michel , Ottonelli Daria , Ponserre Sylvain , Rossi Lauro
Published: March 2024

The characterization of drought hazards remains a complex endeavor, primarily due to the absence of a universally accepted definition for a "drought event." Different deficits across various parts of the water cycle contribute to a spectrum of drought consequences, rendering the definition contingent upon the impacts incurred. Moreover, quantifying drought vulnerability poses challenges given the intricate interplay among socioeconomic, political, and environmental factors that influence the relationship between a drought event and its impacts on exposed production systems, people and nature. Our work addresses these challenges by introducing a novel data-driven methodology employing an array of drought indices and several datasets on observed drought impacts. Applying decision tree-based AI techniques, this method identifies combinations of hydrometeorological conditions known to generate societal consequences, and as such is able to estimate probabilistic drought disaster risk.The presented impact-based approach is generalizable and impacts evaluated include energy production losses, internal displacement, crop and livestock damage, malnutrition, ecosystem health degradation, and strains on drinking water utilities. Illustrated through a case study in the Horn of Africa, this contribution exemplifies the quantification of expected annual drought impact, whereby impact is measured as the number of drought-induced internally displaced persons (IDPs). Drawing on the latest IDMC Displacement Tracking Matrix data, we assessed drought displacement risks under current and projected climate scenarios for Somalia and Ethiopia. Both countries grapple with complex human mobility dynamics, driven by a multitude of push and pull factors. Our findings reveal average annual IDPs up to 2% in some regions in Ethiopia, rising to 3% with unmitigated climate change. In Somalia, the majority of regions are anticipated to experience on average >10,000 drought-induced IDPs annually, under all future projections. Our model demonstrates proficiency in distinguishing prolonged and flash droughts as drivers for displacement. Furthermore, it facilitates the identification of hotspot areas, thereby supporting drought disaster risk reduction decisions and proactive policies.
Tropospheric ozone global and regional distributions and trends from IASI
Authors: Boynard Anne , Wespes Catherine , Hadji-Lazaro Juliette , Hurtmans Daniel , Coheur Pierre-François , Doutriaux Boucher Marie , Bowman Kevin , Clerbaux Cathy
Published: March 2024

Tropospheric ozone (O3) is an important short-lived climate forcer and a critical secondary air pollutant, detrimental to human health and ecosystems. It is the dominant source of the hydroxyl radical OH that is highly reactive with organic and inorganic compounds. Global tropospheric O3 concentrations have been rising considerably since the pre-industrial period as a result of the increase in the anthropogenic emissions of O3 precursors. Assessing the long-term tropospheric O3 trends is critical for understanding the impact of human activity and climate change on atmospheric chemistry.Since 2007, the IASI (Infrared Atmospheric Sounding Interferometer) instruments have been embarked on board the polar-orbiting meteorological satellites Metop-A, -B and -C. The European Organization for the Exploitation of Meteorological Satellites (EUTMETSAT) is currently reprocessing the IASI O3 dataset providing a homogeneous record of O3.In this study, we aim to assess tropospheric ozone distributions and trends on the global and regional scales for the period 2008-2023 using the homogeneous IASI O3 dataset. Comparisons of the IASI data with the Cross-track Infrared Sounder (CrIS) satellite observations are also performed.
Persistent shallow subsurface warming during North Atlantic Stadials drives ice-destabilisation and rapid climate change
Authors: Littley Eloise , Burke Andrea , Shankle Madison , Gray William , Zhang Xu , Sun Yuchen , Roberts William , Rome Yvan , Ivanovic Ruza , Rae James
Published: March 2024

The last ice age was repeatedly punctuated by millennial scale intervals of extreme cold in the Northern Hemisphere. These cold periods, known as stadials, are also times of ice calving and glacial melt, sending debris-laden icebergs into the North Atlantic Ocean, and raising questions about the mechanisms of ice sheet instability. Here, we provide new high resolution marine temperature reconstructions from the northeast north Atlantic (ODP 980 55°29.1’N 14°42.1’W) that show that, whilst persistent cold stadial temperatures might be inferred from abundances of the polar foraminifera Neogloboquadrina pachyderma (% N. pachyderma), Mg/Ca temperature reconstructions from the same planktic species and Globigerina bulloides indicate gradual subsurface warming by as much as 3ᵒC over the course of a stadial. We explain this apparent discrepancy by turning to the seasonal influences on these temperature proxies, suggesting that very high % N. pachyderma reflects preferential survival of this species in polar waters with extensive sea ice, while Mg/Ca reveals relatively mild subsurface conditions during the summer growing season. Modelling shows that warming summers in the high latitude subsurface may be explained by persistent influence of warm waters from lower latitudes, in combination with a lack of winter heat loss due to the insulating effect of sea ice and climbing atmospheric CO2. This accumulation of heat at critical depths for marine terminating glaciers underlines the influence of warming seawater on ice sheet stability and could provide an additional source of heat to trigger abrupt interstadial warming.
Oceanic gateways in Antarctica - Impact of relative sea-level change on sub-shelf melt
Authors: Kreuzer Moritz , Albrecht Torsten , Nicola Lena , Reese Ronja , Winkelmann Ricarda
Published: March 2024

Relative sea level (local water depth) on the Antarctic continental shelf is changing by the complex interplay of processes associated with Glacial Isostatic Adjustment (GIA). This involves near-field visco-elastic bedrock displacement and gravitational effects in response to changes in Antarctic ice load, but also far-field interhemispheric effects on the sea-level pattern. On glacial time scales, these changes can be in the order of several hundred meters, potentially affecting the access of ocean water masses at different depths to Antarctic grounding lines and ice sheet margins. Due to strong vertical gradients in ocean temperature and salinity at the continental shelf margin, basal melt rates of ice shelves could change significantly just by variations in relative sea level alone.Based on a coupled ice sheet – GIA model setup and the analysis of bathymetric features such as troughs and sills that regulate the access of open ocean water masses onto the continental shelf (oceanic gateways), we conduct sensitivity experiments to derive maximum estimates of Antarctic basal meltrate changes, solely driven by relative sea-level variations.Under Last Glacial Maximum sea-level conditions, this effect would lead to a substantial decrease of present-day sub-shelf melt rates in East Antarctica, while the strong subsidence of bedrock in West Antarctica can lead up to a doubling of basal melt rates. For a hypothetical globally ice-free sea-levelscenario, which would lead to a global mean (barystatic) sea-level rise of around +70 m, sub-shelf melt rates for a present-day ice sheet geometry can more than double in East Antarctica, but can also decrease substantially, where bedrock uplift dominates. Also for projected sea-level changes at theyear 2300 we find maximum possible changes of ±20 % in sub-shelf melt rates, as a consequence of relative sea-level changes only.
Effect of pore size distribution on the application of water repellent for preventing deterioration of stone materials.
Authors: Oguchi Chiaki , Ikeda Yukina
Published: March 2024

Treatments intending to prevent stone damage sometimes accelerate deterioration unexpectedly. It would be meaningless if the use of protective agents in a more severe deterioration than originally intended. A combination of the properties between agents and stones determines the ability of protective agents to penetrate the stone. In particular, it is expected to depend on the pore diameter distribution of the stone. The present study focuses on freeze-thaw and salt weathering tests were carried out by using several types of tuffs to verify this. The stone materials used were Oya tuff, Nikka tuff, Tatsuyama tuff, Ashino tuff, and Towada tuff, which have different pore size distributions, different strengths, and different durability to salt weathering. In rocks with a high proportion of micro-pores and low resistance to salt weathering, the use of protective agents (water repellents) can delay the onset of surface deterioration. On the other hand, rocks with a high proportion of large pores (>100.5 µm) and not less resistant to salt weathering were found to be more likely to deteriorate more severely with an earlier onset of surface deterioration than untreated stones. It is considered to be because the salts crystallize at greater depths when protective agents are applied, whereas they crystallize only at the surface in the case of untreated rocks, and the crystalline pressure causes fracture from the deeper layers. Therefore, when using protective agents, it is necessary to understand the combination of rock properties such as rock structure, pore size, and strength of the rock sample with crystal pressure.
Hourly 0.1° Gridded Near Real-Time Precipitation (1979–Present) via Machine Learning Fusion of Satellite, Model, and Gauge Data
Authors: Beck Hylke , Wang Xuetong , Alharbi Raied
Published: March 2024

We introduce a new version of the gridded near real-time Multi-Source Weighted-Ensemble Precipitation (MSWEP) product, developed to address the urgent need for accurate precipitation (P) data in the face of escalating climate change challenges. The product has an hourly 0.1° resolution spanning 1979 to the present, and is continuously updated, with a latency of approximately one hour. The development process involves two stages. Firstly, baseline P fields are generated from multiple satellite and (re)analysis P products, along with several static P-related variables, using random forest models trained on 3-hourly and daily P observations from gauges across the globe (n=17,322). Subsequently, these baseline P fields are locally corrected using available daily P observations, employing a procedure that accounts for the reporting times of gauges. To assess the accuracy of the product, we conducted the most comprehensive global evaluation of P products to date, using daily observations from independent P gauges as a reference (n=15,184). The new P product (prior to gauge corrections) outperformed all 18 other evaluated products, attaining a mean daily Kling-Gupta Efficiency (KGE) value of 0.65. In contrast, widely used products such as CHIRP, ERA5, GSMaP, and IMERG achieved mean KGE values of 0.31, 0.57, 0.37, and 0.40, respectively. Furthermore, our P product consistently ranked first or second across various metrics, including correlation, overall bias, peak bias, wet days bias, and critical success index. Notably, the new product also outperformed several gauge-based products like CHIRPS and CPC Unified, which had mean KGE values of 0.37 and 0.54, respectively. Set for release in late 2024, we anticipate that the new product will be useful for climate research, water resource assessment, and flood management, among numerous other potential applications.
Direct and indirect nitrous oxide emissions with application of nitrification inhibitor and plant growth regulator in a calcareous soil 
Authors: Mirkhani Rayehe , Shorafa Mehdi , Dercon Gerd
Published: March 2024

Numerous studies have shown that nitrification inhibitors (NIs) are an effective tool to reduce direct N2O emissions. However, some studies have showed the positive effect of NIs on ammonia volatilization and increase the indirect N2O emission from AV. This study aimed to investigate the effect of nitrapyrin (NP) as a NI and gibberellic acid (GA3) as a plant growth regulator (PGR) on direct and indirect N2O emissions. A randomized complete block design including three treatments and five replicates was used in this study. The treatments were: T1 (control treatment-without N fertilizer), T2 (Urea only), and T3 (Urea+NI+GA3). Urea was applied in three split applications. GA3 was foliar sprayed only at stem elongation stage. NP and GA3 were applied at a rate of 0.51% and 0.03% of the applied N (weight/weight), respectively. Ammonia volatilization was measured with semi-static chambers and direct N2O emission was measured with static chambers. Cumulative N2O was 1.45 ± 0.13 and 1.11 ± 0.10 (kg N2O-N ha-1) in urea alone and urea in combination of NP+GA3. The estimated values of indirect N2O-N produced from AV in urea and urea+NP + GA3  were 0.38 and 0.45 kg N ha− 1, respectively. The results showed that the indirect N2O emission from the ammonia path in this type of soil which has high pH cannot be ignored and should be included in the net emission. Also, the results showed that the increase in the indirect emission of N2O from ammonia path induced by NP is negligible. 
Eddy effects on South Atlantic Ventilation Pathways using Lagrangian trajectories  
Authors: Schäfers Simon , Griesel Alexa , Chouksey Manita
Published: March 2024

The Southern Ocean takes up a significant amount of anthropogenic CO2 emissions by subduction, as dense water masses get displaced northward and form the Antarctic Intermediate Water (AAIW).  Subducting oceanic water masses encapsulate dissolved atmospheric gases and retard anthropogenic climate change by taking up about a quarter of industrial CO2 emissions, nearly half of which in the Southern Ocean. However, the processes that control the water mass formation and their ventilation pathways, relevant to climate change remain actively researched. Southern Ocean dynamics are strongly influenced by mesoscale eddies which are likely to intensify in a warmer global climate, raising the question on the role and importance of eddies in shaping the ventilation pathways and in oceanic tracer and heat uptake. Previous results using Lagrangian backtracking and tracer simulations in the South Atlantic Ocean indicate heterogeneous source regions and pathways for AAIW, suggesting the potential role of eddies in addition to wind stress-induced Ekman Transport. Here we investigate the impact of mesoscale eddies on the subduction timescales and ventilation pathways of the AAIW in the South Atlantic Ocean.     We use an eddy-resolving 1/10 degree ocean model (Parallel Ocean Program) with a Lagrangian particle tracking algorithm (Parcels) following discrete particles from the interior of the South Atlantic AAIW backward in time until they reach the mixed layer after tracking them for 100 years. In total 105 particles were released in the South Atlantic Ocean between 15° and 40°S in depths that meet the density criteria of 26.8 to 27.4 kg/m3  for the AAIW. The experiment was performed on a repeated year velocity field with daily mean data from 1990. For comparability, we performed the same experiment on a decadal mean state, eliminating mesoscale eddy activity. The Transit Time Distributions (TTD) inferred from the backtracking of Lagrangian trajectories aid in quantifying eddy effects on the advection time scales, source regions, and pathways of the AAIW. We expect eddy effects to alter the position and time scales of the subduction process and affect the importance of specific routes, such as the cold and warm water routes.
Transversal structures in the Main Ethiopian Rift and implications for rifting, volcanism and geothermal systems
Authors: Corti Giacomo , Benvenuti Marxo , Keir Derek , Sani Federico
Published: March 2024

Although systems of extension-orthogonal normal faults are the typical expression of continental rifting, structures oblique or even sub-parallel to the plate motion vector may at places develop. These transversal structures, which may be related to reactivation of pre-existing structures, have been suggested to have a control on rift-related volcanism and caldera systems (for instance controlling their extension-parallel elongation) and on the circulation of fluids in geothermal fields associated to these volcanic features. Here we present data from the central sector of the Main Ethiopian Rift showing the existence of a major NW-SE trending system, which likely resulted from the linkage of major segments of the Main Ethiopian Rift exploiting pre-existing structures. This transversal structure, characterised by both a normal and right lateral slip component, influenced the morphology, hydrography, seismicity and volcanism in the area. Specifically, this NW-SE structure, and the interaction with the NE-SW faults delimiting the rift, controlled the location and alignment of silicic volcanism in the Bora-Bericha and Tulu Moye systems. Seismicity analysis indicates that this transverse structure is still active, reaching at least mid-crustal depths, and indicates that this structure is involved in the fluid circulation at upper crustal levels in the associated geothermal system. Therefore, transverse structures may have important influence on rift evolution and architecture and on the pathways of magma and on the flow pattern of crustal fluids, with important implications for geothermal activity related to continental rifting, as suggested for other important geothermal fields in the Main Ethiopian Rift.
Nature-based solutions for climate resilience in EU R&I framework programmes Horizon 2020 and Horizon Europe
Authors: Barbu Giorgiana-Raluca , Niță Mihai-Răzvan
Published: March 2024

The main concern with public policies and strategies for integrating nature-based solutions is to facilitate access to innovative interventions to reach cities and communities that are more sustainable and climate resilient. However, there is an impediment to linking information on the results of projects and the expected impact of the European Commission in the framework programmes for research funding. Here we show how projects targeting nature-based solutions help to implement and review public policies under the EU Strategy for Adaptation to Climate Change 2013 – 2020 and European Green Deal. These policies have a positive impact in various areas, especially in green transition, with the potential to analyse the link between the scientific results of nature-based projects and the strategic orientations of research and innovation. We focused on the evaluation of 150 projects funded at the Horizon 2020 and Horizon Europe level, within three main programmes that provide funding for projects based on nature, resilience and adaptation to climate change: (1) Climate action, Environment, Resource Efficiency  and Raw Materials, (2) Climate, Energy and Mobility and (3) Food, Bioeconomy, Natural Resources, Agriculture and Environment. The main analyzed elements are the number and type of partners, the level of funding, the main objectives of the projects, types of nature-based solutions and their distribution by geographical regions in Europe. This analysis leads to the filling in the existing knowledge of the results that produce science, so that it can be exploited throughout the community. Our results consist in (1) overview of climate challenges in EU R&I framework programmes Horizon 2020 and Horizon Europe, (2) Main NBS designed by European R&I organizations, (3) NBS for climate resilience implemented through EU R&I funding in Horizon 2020 and Horizon Europe, (4) NBS for climate resilience – key pathways of knowledge valorization for ecosystem restoration, preservation and management. Overall, they show that the aspects analyzed in the selected funded projects support the development of nature-based solutions and what are the main actions that lead to long-term impact.
Nile Basin vegetation and Mediterranean water column ecology during Sapropel formation 
Authors: Wörmer Lars , Fernández-Guerra Antonio , Morard Raphaël , Zure Marina , Pedersen Mikkel Winther , Hassenrück Christiane , Kucera Michal , Willerslev Eske , Hinrichs Kai-Uwe
Published: March 2024

For millions of years, the Mediterranean Sea has regularly experienced episodes of disrupted thermohaline circulation and increased primary productivity that resulted in a largely anoxic water column. These anoxic episodes are typically related to a more humid climate over Northern Africa and are captured in the sedimentary record as organic-rich sapropel layers. Given the excellent preservation of organic molecules in them, sapropels are extraordinary archives for the marine and continental ecosystems associated with the unique conditions that prevailed during their formation. We applied metagenomic environmental DNA (eDNA) analysis to recent sapropels (< 175 kyr) from the Eastern Mediterranean, including Sapropel S5 deposited during the Last Interglacial, and benchmarked obtained results with high resolution geochemical and molecular biomarker records. Ancient eDNA analysis enables reconstructions across all domains of life, including those components of the ecosystem that do not leave fossils or are not recorded in the fossil record. In the case of Mediterranean sapropels, this approach reveals information on both terrestrial and marine ecosystems. We provide detailed insight into vegetation changes in the Nile River Basin during the different, climatically diverse episodes of sapropel deposition. On the marine side, we reveal how water column ecology and major elemental cycles adapted to this massive ecosystem overhaul.
The potential of high density seismic arrays to elucidate distributed deformation in the Dinarides and Hellenides
Authors: Tilmann Frederik , Rietbrock Andreas , Schurr Bernd , Heit Ben , Frietsch Michael , Agurto-Detzel Hans , Gao Ya-Jian , Kufner Sofia-Katerina , Dushi Edmond , Rama Besian , Koxhaj Damiano , Sindija Dinko , Petersen Gesa , Sokos Efthimios , Faccenna Claudio , Meier Thomas , Kolinský Petr
Published: March 2024

The eastern Adriatic margin with the Dinarides and Hellenides orogens is one of the most hazardous areas in Europe from an earthquake hazard perspective in spite of only moderate shortening rates (e.g. less than 0.5 cm/yr across the Dinarides), as exemplified by the recent highly damaging earthquakes in Durrës, Albania (2019, M6.4) and Petrinja, Croatia (2020, M6.4). Deformation is both fairly localised on shallowly NE dipping thrust faults near the coast, and distributed, with a transition to spatially extended extensional deformation in the southern Dinarides and Northern Hellenides. and a complex regime involving strike-slip and obblique mechanisms in the eastern part of the Northern Dinarides. Making sense of this distributed deformation requires highly accurate locations both horizontally and in depth, which can only be achieved with dense seismic observations.This region is thus being explored with multi-scale dense seismic deployments. On one hand, the multi-national AdriaArray initiative has combined temporary and permanent broadband stations to achieve a nearly-uniform coverage with typical inter-station distances of 30-40 km. In Albania, where the transition of the Dinarides to the Hellenides is occurring, this regional coverage is complemented by a ultra-dense deployment of nearly 400 stations (mostly geophones with a few broadband sensors) with a nominal spacing of 5 km, which was later rearranged into three orogen-perpendicular profiles, and one along-strike profile with 1 km station spacing. Such large numbers of stations require automated processing approaches leveraging recently developed machine learning-based techniques. The presentation will review the tectonic context for these surveys and share some preliminary results from these deployments as well as an earlier more localised deployment in the area of the Durrës earthquake.
Revisiting non-tidal atmospheric and oceanic gravity corrections for terrestrial gravimetry
Authors: Balidakis Kyriakos , Antokoletz Ezequiel , Sulzbach Roman , Dobslaw Henryk , Wziontek Hartmut , Voigt Christian , Dill Robert , Timmen Ludger
Published: March 2024

Mass redistribution within Earth’s atmosphere and oceans affects gravity time series recorded by precise superconducting and quantum gravimeters at a multitude of temporal scales. While the largest component of the systematic disturbances is attributed to tides mainly in the oceans, the solid Earth, and to a smaller extent also the atmosphere, synoptic weather features also cause non-negligible gravity anomalies. The accurate description of these effects requires a high-resolution representation of certain components of the instantaneous Earth system state, namely the 3D atmospheric density and the ocean bottom pressure distribution. In this contribution, we calculate gravity anomalies induced by the Newtonian attraction of the mass anomalies and the loading effect they exert on Earth’s crust, employing the state-of-the-art meso-beta scale numerical weather model ERA5 reanalysis from ECMWF. We compare the ERA5-derived gravity anomalies to those provided by ATMACS, a service that features weather-driven gravity anomaly corrections for most superconducting gravimeter sites based on the operational model ICON-global, from the German Weather Service. In this work, we place our focus on non-tidal contributions only, while tidal signatures are estimated based on the gravity anomaly time series. The ocean state is based on a recent MPIOM simulations forced consistently from ERA5 which is also the basis of the latest GRACE/GRACE-FO non-tidal atmosphere-ocean dealiasing product AOD1B RL07. To assess the effectiveness of the modelling strategy as well as the quality of the mass anomaly fields, we apply the ERA5 and ATMACS-retrieved models to a few selected superconducting gravimeter time series with a focus on sites with unusual orography such as on the small island of Helgoland located in the North Sea, and assess the band-pass filtered residuals to assess the quality of the various correction models available.