bluuebunny/crossref_metadata_2025 huggingface dataset:
ACTRIS - University of Helsinki Topical Centre units provide support for measurements of secondary aerosol formation
Authors: Sarnela Nina , Lampilahti Janne , Petäjä Tuukka , Lehtipalo Katrianne , Häme Silja
Published: March 2024

ACTRIS is a European distributed research infrastructure producing high-quality data on short-lived atmospheric constituents. ACTRIS facilitates free access to long-term atmospheric data and access to its world-class facilities and extends its resources to academia, the private sector, and the general public. The infrastructure comprises National Facilities, encompassing observational and exploratory platforms, and Central Facilities that support these units through training, guidelines, and standard operation procedures.University of Helsinki (UH) is hosting two specialized Topical Centre Units dedicated to standardizing measurements of secondary aerosol formation. The Cluster Calibration Centre (CCC) focuses on sub-10nm aerosol particle concentration and size distribution measurements, while CiGas-UHEL concentrates on condensable trace gases, which can serve as aerosol precursors.The main tasks of the UH Topical Centre Units are to 1) provide training and consultancy, 2) produce and provide measurement and data procedures and tools 3) improve the methods to calibrate the relevant instrumentation and provide instrument calibrations for ACTRIS National Facilities, 4) organize calibration and intercomparison workshops and 5) carry out measurement and calibration method and instrument development.
Currently, both CCC and CiGas-UHEL are at the midpoint of their implementation, with full operative capacity anticipated by 2026. In the past year, significant strides were made with piloting ACTRIS intercomparison workshops. CiGas-UHEL hosted the 1st Chemical Ionization Mass Spectrometer intercomparison workshop in March 2023 (Leipzig), while CCC organized the 1st Neutral cluster and Air Ion Spectrometer (NAIS) intercomparison workshop in May 2023 (Helsinki) and the 1st Nanoparticle instrument intercomparison workshop in November 2023 (Helsinki). These workshops serve as critical platforms, providing essential insights into measurement techniques and instrument functionality .
Quantitative Measurement of Landscape Features in EU Agriculture: A Novel Indicator Approach 
Authors: d'Andrimont Raphaël , Skøien Jon , Musavi Talie , Iordanov Momtchil , Gallego Javier , De Marchi Davide , Koeble Renate , Guerrero Irene , Montero-Castaño Ana , Terres Jean-Michel , Czúcz Bálint
Published: March 2024

The conservation and creation of landscape features is recognised as a key conservation tool to halt the loss of agricultural biodiversity in European farmland.This study introduces a new indicator to quantify landscape features in EU agricultural land, based on the LUCAS Landscape Feature survey. We developed a comprehensive methodology to measure and categorise landscape features, distinguishing Woody, Grassy, Wet, and Stony LF types. Our approach gives a robust and reproducible estimate of the indicator at the EU Member State and possibly regional levels, based on a reliable and statistically representative sample of landscape features.The methodology combines office-based photo-interpretation with field surveys collecting 3.8 millions field points, ensuring accuracy in determining the presence and type of landscape features within agricultural contexts. Together with information on biodiversity and ecosystem services, it will play a crucial role in evaluating the performance of major policies related to biodiversity conservation in agricultural lands, aligning with the Common Agricultural Policy and the EU Biodiversity Strategy for 2030. Besides, it will play a role in the assessment of natural based solutions for mitigating climate change effects, biodiversity loss and crop production (food) security.Our findings reveal that, in 2022, landscape features covered 5.6% of EU agricultural land. Woody features were the most prevalent, followed by Grassy, Wet, and Stony features. The percentages of landscape features varied across EU Member States, with Malta and Cyprus exhibiting higher values.The novel indicator developed is based on a comprehensive and reproducible method for quantifying these features, providing essential insights for policy and decision-making in sustainable agriculture.
Mapping the Landscape of Research on Wind Disturbance in Forests: A Comprehensive Bibliometric Analysis and Systematic Review
Authors: Gao Wen , Larjavaara Markku
Published: March 2024

Forests are susceptible to sudden disturbances, particularly those induced by wind, which can cause ecological and economic losses. Researchers have published a large number of articles from different disciplines and perspectives, leading to multidisciplinary intersections and increased literature in this field, which reduces the efficiency of traditional literature review. Employing quantitative techniques, bibliometric analysis has a great advantage in analyzing large amounts of literature and providing a visualized overview of the development and trends of the research field. This study conducted a comprehensive bibliometric analysis to elucidate the evolving landscape of research on forest wind disturbance. The methodology involved a systematic data collection process from the Web of Science Core Collection, resulting in the identification of 839 relevant publications for bibliometric analysis. The results show that there has been a consistent and steady growth in publications, with a distinct spike corresponding to Hurricane Hugo. Publications have mostly come from the United States, which also possesses the leadership in international collaboration. The standout topics include windthrow, tree motion during windstorms, European forests, wind damage risk estimation, hurricanes' impact on forests, and the long-term impacts of wind disturbances. Furthermore, four prospective directions for future research are identified, including studies into hurricanes, forest structure, climate change, and typhoon-related impacts. Our research collectively contributes to a comprehensive understanding of the dynamic landscape of forest wind disturbance research, providing a foundation for future research and strategic planning in this critical field.
Two-step unsupervised clustering method on soil nanoscale secondary ion mass spectrometry (NanoSIMS) images to determine the spatial arrangement of minerals and organic matter
Authors: Hu Yahan , Zollner Johann , Werner Martin , Schweizer Steffen , Höschen Carmen
Published: March 2024

In the soil, mineral particles, organic matter, and soil organisms are arranged in a complex architecture which can influence organic matter dynamics. Nanoscale secondary ion mass spectrometry (NanoSIMS) provides insights into the microscale arrangement of soil minerals and organic compounds at a resolution of approximately 50 nm. However, current NanoSIMS image processing lacks methods to analyze large datasets automatically and requires manual intervention. We developed a two-step unsupervised clustering method for batch analyses of NanoSIMS images. Our two-step method consists of K-Means clustering as the first step generating around 100 clusters, followed by hierarchical agglomerative clustering (HAC) re-grouping the K clusters into less than 10 cluster groups. The elbow method, HAC linkage method and gap statistics are used to automatically select the optimal clustering numbers. Subsequently, soil minerals and organic matter can be spatially segmented and identified as different species. Further, this method could apply to the spatial arrangement of mineral-dominated and organic matter-dominated parts or different mineral types. Moreover, this method enables the analyses of larger datasets with >100 NanoSIMS images providing insights of organo-mineral interactive hotspots or even micro function domains involved in soil organic matter dynamics.
Characterizing the space-time evolution of wet channels in a non-perennial Mediterranean catchment exploiting a network of camera traps
Authors: Noto Simone , Durighetto Nicola , Tauro Flavia , Grimaldi Salvatore , Botter Gianluca
Published: March 2024

Non-perennial streams are those streams that periodically cease to flow in at least one point along their network. The research community well recognizes the importance of such watercourses for they have a global prevalence and provide diverse hydrological functions and ecosystem services. The spatiotemporal pattern of the active drainage network is anything but simple, sometimes showing a very complex pattern. Non-perennial streams, in fact, are often located in heterogeneous environments, in which the combination of climate, morphology, land cover, soil, substrate, and anthropic factors could play a role in the observed drying and wetting patterns. This work combined two techniques, with different spatiotemporal resolutions, to characterize the spatiotemporal extent of the stream network in a 3.7 km2 Mediterranean catchment of central Italy. The hydrological status of a set of nodes of the network was derived for the period 2020-2022 from sporadic visual surveys and, most importantly, through the analysis of sub-hourly images collected by 21 cameras distributed along a set of strategic nodes of the network. The latter technique is particularly promising to reconstruct the hydrological dynamics taking place in the target cross-section, as the temporal evolution of the underlying hydrological conditions (wet vs. dry), the water stage, and the corresponding discharge can be inferred from the automatic or manual analysis of the acquired images. The available experimental data  was combined exploiting the hierarchical principle, that postulates the existence of a Bayesian chain based on the local persistency of the nodes that dictates their drying/wetting order during stream retraction/contraction cycles. The results highlighted the complexity of the network dynamics in the study area: while the number of wet nodes decreased during the dry season and increased during the wet season, the local persistency of the nodes showed a highly heterogeneous and non-monotonic pattern, resulting in a dynamically disconnected network. The approach allowed the reconstruction of the entire river network and represented a useful tool to estimate the extent of its wet portion, even in case part of the network could not be inspected. This work represents a novel approach to reconstruct the extension of the wet portion of the stream network in difficult-to-access environments, where traditional techniques might be inadequate.
Influence of particle's buoyancy on turbidity currents from continuous influx
Authors: Mercier Matthieu , Schneider Jean , Gadal Cyril , Lacaze Laurent
Published: March 2024

We investigate experimentally the dynamics of particle-laden gravity currents originating from a continuous influx in a nearly steady regime. We seek to characterize the influence of suspended particles on the inner structure of the current, depending on their settling/rising properties.
The compositional fluid for the current is obtained by adding salt (NaCl) to the ambient fluid of the density ρ0, the density difference of the current with the ambient fluid is noted Δρ0. In the case of particle-laden gravity currents, we add plastic particles (diameter 500 µm and density 1050 kg/m3) in a semi-dilute concentration (Φ ~ 1%). We can also change the settling/rising properties of the particles by choosing the density of the fluid in the current, the density ratio varying between R=0.98 (rising particles) and R=1.02 (settling particles). Once prepared, the compositional fluid, stored and continuously stirred in a large reservoir, is injected in a nearly two-dimensional long tank by a pump at fixed flow rate Q, long durations of injection are possible by using either a very long tank, or an open channel configuration. Two setups have been used, associated to turbulent regimes, with typical Reynolds number of the order of 103 to 104 respectively. Within the body of the current, the density/concentration profiles are estimated by light attenuation technique [1].
Our results show that the front velocity Uf is well controlled by a characteristic velocity based on the buoyancy of the current and the flow rate per unit width, as shown in Figure 1(a). Depending on the height of the injection inlet h0, the current can exhibit different hydraulic features near the front, depending on the value of the Froude number at the inlet F0, defined as the ratio of Uf over (Δρ0/ρ0 . g . h0)1/2, with g the gravity constant, being supercritical (F0>1) or subcritical (F0
Deciphering Radon Variability in the Northern Upper Rhine Graben: An Analysis Using Passive and Active Detection with Random Forest Modelling
Authors: Mair Johannes , Petermann Eric , Lehné Rouwen , Henk Andreas
Published: March 2024

This study, conducted about 30km south of Frankfurt in the Northern Upper Rhine Graben, focuses on deepening the understanding of Radon concentrations in soil air. The selected area, where neotectonic activity was proven in an accompanying project, provides an ideal setting for investigating Radon variability, particularly its potential correlation with fault zones in unconsolidated rocks or sedimentary basins. Understanding the factors influencing Radon levels in the environment is a complex task, as they are affected by a multitude of variables. Our work aims to decipher these influences and, if possible, quantitatively analyse the contributions of each variable. By doing so, we hope to gain a clearer understanding of how different environmental factors interact to determine Radon levels.A central element of our research is the use of Random Forest models, chosen to handle our multidimensional dataset. This dataset includes a variety of parameters such as Radon measurements, nuclide content, soil grain sizes, weather data, and the distance to fault zones. Random Forest models are particularly effective for this type of complex data because they can analyse many different factors at once and uncover hidden patterns.Contrary to initial hypotheses, our findings indicate that in unconsolidated rocks and sedimentary basins, the grain size of soil is the most influential factor in determining soil air Radon levels, closely followed by soil moisture. These results challenge the previously held belief that fault zones are the primary influencing factors on Radon concentrations in these geological settings.
Eastern North China Craton–North Australia Craton connection at 1.0 Ga through detrital zircon modelling
Authors: Zhang Wen , Xu Wang , Liu Pinghua , Liu Chaohui , Liu Fulai
Published: March 2024

More and more similar Grenvillian orogeny-related late Mesoproterozoic detrital zircon age peaks reported from ca. 1.0 Ga strata among the Rodinia blocks make paleogeography reconstruction of the North China Craton more puzzling. In this work, we compile detrital zircon U-Pb data of the late Mesoproterozoic–early Neoproterozoic strata in the eastern North China Craton (ENCC) with coeval or older rock units from the potential provenances (e.g. North Australia, Siberia, Laurentia and India/Greater India cratons and the North Atlantic region), and present inverse Monte Carlo modelling. The result confirmed that ca. 1.0 Ga ENCC–North Australia Craton connection is most plausible, which is first quantitatively evaluated.
How to Limit the Epistemic Failure of Machine Learning Models?
Authors: Renouard Alexandra , Stafford Peter , Goes Saskia , Whittaker Alexander , Hicks Stephen
Published: March 2024

The intelligible understanding of natural phenomena such as earthquakes is one of the main epistemic aims of science. Its very aims are shaped by technological discoveries that can change the cognitive fabric of a research field. Artificial intelligence, of which machine learning (ML) is one of the fundamental pillars, is the cutting-edge technology that promises the greatest scientific breakthroughs. In particular, great hopes are placed in MLmodels as a source of inspiration for the formulation of new concepts or ideas, thanks to their ability to represent data at different levels of abstraction inaccessible to humans alone.However, the opacity of ML models is a major obstacle to their explanatory potential. Although efforts have recently been made to develop ML interpretability methods that condense the complexity of ML models into human-understandable descriptions of how they work and make decisions, their epistemic success remains highly controversial. Because they are based on approximations of ML models, these methods can generate misleading explanations that are overfitted to human intuition and give an illusory sense of scientific understanding.In this study, we address the question of how to limit the epistemic failure of ML models. To answer it, we use the example of an ML model trained to provide insights into how to better forecast newly emerging earthquakes associated with the expansion of hydrocarbon production in the Delaware Basin, West Texas. Through this example, we show that by changing our conception of explanation models derived from interpretability methods,i.e. idealised scientific models rather than simple rationalisations, we open up the possibility of revealing promising hypotheses that would otherwise have been ignored. Analysis of our interpreted ML model unveiled a meaningful linear relationship between stress perturbation distribution values derived from ML decision rules and earthquake probability, which could be further explored to forecast induced seismicity in the basin and beyond. This observation also helped to validate the ML model for a subsequent causal approach to the factors underlying earthquakes.
Increase in strength and orbital variability of the South Pacific Antarctic Circumpolar Current across the Mid-Pleistocene Transition
Authors: Lamy Frank , Winckler Gisela , Arz Helge , Farmer Jesse R. , Lembke-Jene Lester , Gottschalk Julia , Toyos Maria
Published: March 2024

The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean current system and impacts global ocean circulation, climate, and Antarctic ice sheet stability. Today, ACC dynamics are controlled by atmospheric forcing, Southern Ocean density gradients, and mesoscale eddy activity in the southern high latitudes. Yet, its role in driving the lengthening and intensification of glacial cycles is insufficiently studied. Here, we present a 1.5 Ma-record of changes in ACC strength based on bottom water flow reconstructions and sedimentary opal contents at IODP Sites U1540 and U1541 drilled in the Subantarctic Zone (SAZ) of the Pacific Southern Ocean. Our new data indicate that glacial and interglacial ACC strength gradually increased between ~1.3 and ~ 1 Ma coinciding with the early part of the MPT. This interval culminates in a pronounced ACC maximum during Marine Isotope Stage (MIS) 31 at ~1 Ma reaching ~160 % of the mean Holocene values. The increase in subantarctic ACC strength during the initial part of the MPT is paralleled by the emergence of stronger orbital-scale fluctuations in opal contents at both Sites U1540 and U1541 after MIS 31, suggesting a link between the onset of consistently higher amplitude glacial-interglacial fluctuations of ACC changes and latitudinal shifts of the ‘opal belt’ in the Southern Ocean. Specifically, higher opal contents correlate to decreased ACC strength, suggesting that the opal belt extended northward into the SAZ during glacials. We argue that the early change in ACC dynamics at the beginning of the MPT might be linked with sea surface temperature changes in the eastern subtropical and tropical Pacific, because surface cooling by ~2-3 °C at ODP Site 1237 off Peru between ~1.05 Ma and ~0.8 Ma parallels the reconstructed ACC strengthening at IODP Sites U1540 and U1541. This may result from enhanced advection of subantarctic water masses northward along the Humboldt Current system as a response to the intensification of the ACC starting during MIS 31. Our findings emphasize a contribution of Southern Ocean processes to the climate events causing intensification of glacial-interglacial climate variability during the MPT.
Stress and Strain Changes in Response to Reservoir Water Level Variations – A Case Study of the Enguri High-Head Arch Dam in the Caucasus
Authors: Niederhuber Thomas , Müller Birgit , Westerhaus Malte , Rietbrock Andreas , Weisgerber Jakob , Röckel Thomas , Karamzadeh Nasim , Tsereteli Nino , Tugushi Nazi , Kalabegishvili Mirian , Svanadze David , Schilling Frank
Published: March 2024

Hydropower facilities utilize the potential energy of water to generate electricity, with maximum efficiency achieved when there is a significant topographic gradient between reservoir and turbines. Therefore, high dams are typically built in regions with rugged topography, often associated with (frequently combined) erosion, folding or displacement along fault zones, leading to juxtaposed different material properties.At the Enguri Arch Dam in Georgia, extensive limestone formations from the Cretaceous and Jurassic were thrust southward, resulting in a topography difference exceeding 1000 m between the southward-extending Rioni Basin and the contiguous mountain ranges. The reservoir extends about 25 km to the north. There, nearby mountains reach heights of 3000 m and more. As part of the ongoing crustal shortening process, multiple fault systems have emerged, including prominent SW-NE trending thrust faults, steep strike-slip faults, and to a minor extend normal faults.The Enguri valley carves into the surrounding mountains, reaching an elevation of 280 m above sea level at the dam site. These substantial topographic variations between hilltops and valleys establish a variable initial stress field characterized by lateral heterogeneity in both magnitude and orientation. The initial stress conditions were determined using borehole imaging data and hydraulic fracturing tests, while the mechanical properties of the subsurface materials were evaluated using mechanical tests on core samples.The Enguri high-head Dam has a construction height of 271 m and the Jvari-reservoir reaches at full level more than 510 m above sea level. Geodetic GNSS and seismic stations were installed to evaluate the impact of the annual water level changes of about 100 m on the surrounding area.The subsurface information on stress conditions and material properties was used to create an elastic 3D model of the area. The modelling results were compared with field observations to gain a better understanding of the dynamic processes in the area. In a first step the initial stress field was simulated. Loads were applied to simulate the water level changes. Modelled and observed displacements indicate that rising water level causes the west bank to move north-west, while the east bank moves south-east. Furthermore, both banks of the valley show a downward movement. Conversely, when the water level decreases, the effect is reversed. Variations in water level induce changes in the shear stress and changes in Coulomb Failure Stress (ΔCFS) calculated for different fault orientations. They reveal an increased seismic potential during low water levels, aligning with first seismic observations.
Integrating structure-from-motion photogrammetry with 3D webGIS for risk assessment, mapping and monitoring of coastal area changes in the Maltese archipelago
Authors: Colica Emanuele , Fenech Daniel , Gauci Christopher , Buhagiar George
Published: March 2024

The Maltese coasts extend for approximately 273km, representing a notable resource for the country and of one of its pillar economies, the tourism sector. Natural processes and anthropic interventions continue to threaten Malta's coastal morphology, shaping its landscape and triggering soil erosion phenomena. Therefore, many research projects (Colica et al., 2021, 2022 and 2023) have concentrated their work on the investigation and monitoring of the instability of cliffs and the erosion of pocket beaches. The results of such activities can be widely disseminated and shared with expert and non-expert users through web mapping, which has only been used in a very limited way in collaborative coastal management and monitoring by different entities in Malta. This study describes the performance of a WebGIS designed to disseminate the results of innovative geomatic investigations for monitoring and analyzing erosion risk, performed by the Research and Planning Unit within the Public Works Department of Malta. While aiming to include the entire national coastline, three study areas along the NE and NW regional coasts of the island of Malta have already been implemented as pilot cases. This WebGIS was generated using ArcGIS pro software by ESRI and a user-friendly interactive interface has been programmed to help users view in 2D and 3D, satisfying both multi-temporal and multi-scale perspectives. It is envisaged that through further development and wider dissemination there will be a stronger uptake across different agencies involved in coastal risk assessment, monitoring and management.ReferencesColica, E., D’Amico, S., Iannucci, R., Martino, S., Gauci, A., Galone, L., ... & Paciello, A. (2021). Using unmanned aerial vehicle photogrammetry for digital geological surveys: Case study of Selmun promontory, northern of Malta. Environmental Earth Sciences, 80, 1-14.Colica, E. (2022). Geophysics and geomatics methods for coastal monitoring and hazard evaluation.Colica, E., Galone, L., D’Amico, S., Gauci, A., Iannucci, R., Martino, S., ... & Valentino, G. (2023). Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images. Remote Sensing, 15(5), 1465.
High-temperature CO2 mineralisation in basaltic rocks: Inconsistencies between laboratory experiments and numerical modelling 
Authors: Berndsen Maximilian , Erol Selçuk , Akın Taylan , Akın Serhat , Nardini Isabella , Immenhauser Adrian , Nehler Mathias
Published: March 2024

The Nesjavellir high temperature geothermal reservoir, located in southwest Iceland, was one of the test sites for the 'Geothermal Emission Control' (GECO) project. The project involves the reinjection of exhaust gases from geothermal power plants into the subsurface for permanent storage. Numerical modelling and field data from the nearby CarbFix2 storage site at Hellisheiði indicate that even at high temperatures (< 280°C), large quantities of CO2 can be mineralised. To complement these data, we investigated the potential for CO2 sequestration in the Nesjavellir reservoir by conducting a 260 °C batch reaction experiment using a basaltic drill core sample and effluent water from the Nesjavellir injection well. We also simulated the experiment using the PHREEQC geochemical modelling program and observed significant inconsistencies between the modelled and experimental results. The experiment produced a secondary mineral assemblage dominated by zeolites, chlorites and anhydrite, with no carbonates observed. In contrast, the model predicted the formation of calcite, which did not occur during the experiment. This discrepancy is due to the model's inability to handle solid solutions and non-ideal phases adequately. During the experiment, Ca was primarily incorporated into anhydrite and a Na-Ca-zeolite, which resembles a solid solution of wairakite and analcime. However, the model did not consider this phase, which resulted in Ca being incorporated into calcite instead of zeolite.The experimental results are consistent with previous studies that show limited carbon mineralization at higher temperatures (> 180 °C) due to the competition between carbonates and silicates for the uptake of divalent cations. In addition, a comparison with the numerical model shows that simulations of high-temperature CO2 sequestration can be misleading as they may not be able to reproduce the complexity of non-ideal silicate mineral formation, resulting in an overestimation of carbonate formation.
Temporal dynamics of subglacial methane emissions revealed through continuous measurements at the margin of the Greenland Ice Sheet
Authors: Sapper Sarah Elise , Jørgensen Christian Juncher , Adnew Getachew , Blunier Thomas , Christiansen Jesper Riis
Published: March 2024

Methane (CH4), produced subglacially and transported dissolved in meltwater, is released at glacier margins and contributes to atmospheric methane. Recent research expands our spatial understanding of subglacial methane production, extending beyond the large Greenland Ice Sheet to smaller mountain glaciers. However, emission patterns through an entire melt season remain poorly understood due to challenges in long-term measurements in these remote locations. Continuous measurements are crucial for accurately assessing the relation to glacial melt, total emissions, and potential future impact on the atmospheric CH4 budgets.Our study investigated the seasonal variation of dissolved methane (dCH4) export at a lateral outlet of the Isunnguata Sermia glacier in West Greenland. We used custom-built sensors for continuous measurements that were compared to on-site samples of hydrochemistry and water isotopes alongside the continuous monitoring of water levels and water temperature.The observed patterns of dCH4 concentrations reveal the influence of several interconnected processes, varying on both diurnal and seasonal scales. These processes encompass changes in the connectivity of subglacial meltwater channels to sediment pockets with CH4 production, mixing with fluctuating volumes of CH4-free supraglacial meltwater routed through englacial conduits and variations in the volume of air-filled headspaces of the drainage system following discharge fluctuations. A connection to sediment pockets is hypothesized to elevate the dCH4 concentrations measured at the glacier margin, while increased volumes of supraglacial meltwater are associated with lower dCH4 concentrations, as are larger volumes of air-filled headspaces in channels at low discharge due to degassing from the water phase.We will present how temporal variations in dCH4 concentrations link to climatic variability influencing water flow over the season and their relation to geochemical indicators and water isotopes as tracers for meltwater types. Insights gathered from three seasons of measurements highlight the limitations of discrete samples and accentuate the importance of continuous monitoring in obtaining realistic estimates of subglacial CH4 emissions through upscaling and accurately assessing climate implications.
Interactions between deep seismicity and shallow deformation in the Japan trench and Chile subduction zones 
Authors: socquet anne , Chouli Audrey , Gardonio Blandine , Jara Jorge , Giffard Roisin Sophie , Marsan David , Bouchon Michel
Published: March 2024

Recent great subduction earthquakes have been preceded by an accelerated rate of both interface seismicity along the megathrust and intermediate depth seismicity within the slab at ~100km depth (e.g. Bouchon et al., 2016, 2018), sometimes along with seismicity lineaments along dip over some hours (Bouchon et al., 2022, 2023). These may also be associated with large-scale gravity and mass changes in the subduction zone (Panet el al. 2018). Such interactions between deep and interface seismicity can last several years and can be associated with deformation within the upper plate (Durand et al., 2014; Jara et al. 2018, Rousset et al. 2023, Mitsui et al. 2021).However such interactions between deep seismicity and shallow deformation have been observed only on rare occasions. In addition, assessing better how they relate to fluid transfer and slab force balance is key to improved understanding of the driving mechanisms of the plate interface destabilization.Here we present some intriguing examples of interactions between intraslab seismicity and shallow deformation, and assess their statistical significance. We show that the occurrence of the Tohoku earthquake significantly changed the deep (>150km) seismicity rate, suggesting that this major megathrust event modified the slab equilibrium down to the lower mantle.We also revisit the interactions between intermediate-depth and shallow seismicity in the Japan trench and the northern Chile subduction zone, during the decade preceding the Tohoku-oki (Mw 9.0, 2011) and Iquique (Mw 8.2, 2014) megathrust events. Cross correlations highlight different periods with significant interactions between intermediate-depth and shallow earthquakes, including the 8 months before the Tohoku-Oki megathrust in Japan, over which multiple bursts of ~7 days are synchronized. In Chile, the 4 months preceding the Iquique megathrust also show strong interactions, with successive bursts of ~4 days. Unlike some other periods, no stress transfer implied by Mw>6 earthquakes can explain the correlations observed before both megathrust events. Clustering of the seismicity allowed to identify along-dip lineament patterns. Their occurrence rate shows a significant increase when approaching the date of the megathrusts. If only a few are observed in Chile, the numerous lineaments downdip Tohoku highlight some structures along which lineaments concentrate. These elongated seismicity features seem to connect intermediate-depth and shallow seismicity and could be explained by fluid migrations.
A Vegetation Photosynthesis and Respiration Model (VPRM) for the post-MODIS era
Authors: Glauch Theo , Marshall Julia
Published: March 2024

The data-driven VPRM model is a simple light-use-efficiency model, driven by satellite-derived indices of Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) to extract information at high spatial resolution. High temporal resolution is provided through meteorological driving data, namely 2-m temperature and shortwave radiation at the surface. Two parameters per vegetation type are fit using flux tower measurements from the region for previous years. This well-established model has been widely used to model carbon exchange fluxes (gross primary productivity and respiration) between the land biosphere and the atmosphere. A common application is as a background (prior) model for estimating carbon fluxes through inversion techniques at regional scales, given the high temporal and spatial resolution of the fluxes compared to complex process models.Historically, the VPRM preprocessor relied on data from the 500-m-resolution MODIS satellite and a static 1-km land cover classification map. As MODIS approaches discontinuation, this presentation introduces an updated VPRM software framework - pyVPRM - capable of handling satellite data from MODIS, VIIRS, and Sentinel-2, as well as high-resolution land cover products from ESA WorldCover and the Copernicus Global Land Service. The extremely high spatial resolution of the Sentinel-2 reflectances and updated land cover maps now allow vegetated area within cities to be resolved. In addition, the framework naturally provides an interface to generate VPRM inputs for use in online mesoscale models, such as the greenhouse gas module of the Weather Research and Forecasting Model (part of the WRF-Chem distribution). In our presentation we provide an overview of the model, present fit parameters for all cases using data from European eddy-covariance towers, and present exemplary applications ranging from city to continental scales.
Are There Carbon-Neutral Cities in South Korea: Using Residual Modeling on Different Spatial Scales
Authors: Jeong Yujeong , Lee Sujong , Hong Mina , Ko Youngjin , Jo Hyun-Woo , Lee Woo-Kyun
Published: March 2024

To achieve the national carbon neutrality goal by 2050, it is crucial to be spatially strategic. Understanding the spatial distribution of carbon balance in different levels of spatial scales from global/continental scales to urban, and province/state is essential. This paper aims to estimate the spatial distribution of carbon balance in South Korea using an integrated carbon balance estimation model and to identify the disparity of carbon-emission characteristics determined by three different spatial divisions ¾ metropolitan and basic local governments, and town-level (eup/myeon/dong&li). Two-step ridge regression model using residuals was established based on land cover maps, population maps, and energy production data to analyse the distribution of carbon emissions. The distribution of carbon sequestration was calculated using the Korean forest growth model (KO-G-Dynamic model). The results from each model were calibrated and validated by the National Greenhouse Gas Inventory of basic local governments. The carbon balance was quantified by integrating the results of carbon emission and carbon sequestration. Surprisingly, the results showed that several cities, especially along the biggest mountain range in South Korea, have already achieved regional carbon neutrality. This is particularly true when the spatial scale is below a metropolitan government level. Additionally, the study found that the narrower the spatial scale of distribution becomes, the greater the number of urban/provinces with a carbon balance under zero. Obviously, carbon-neutral regions are characterized by low energy and industrial facilities and high forest density and, in most of the top emitting regions, vice versa. This study provides insights into the methodology for researching the spatial distribution of carbon balance. It also highlights the need for constructing carbon reduction pathways and strategies that reflect the regionality of carbon balance in multi-level districts. With further development of the study, the result could be used as scientific evidence for the effective fulfillment of regional carbon neutrality.
Improving the resolution of satellite precipitation products in Europe
Authors: Filippucci Paolo , Ciabatta Luca , Mosaffa Hamidreza , Brocca Luca
Published: March 2024

Climate change is increasing the challenges related to extreme weather events, shifting precipitation patterns, causing water scarcity and increasing the occurrence of natural disasters. Accurate and timely precipitation data are critical for understanding and mitigating these events, as well as for informing decision-makers. Specifically, Europe climatic and physiographic features make capturing fine-scale (1 km-daily) variations crucial to improve the precision of climate models and facilitate targeted adaptation strategies in this area.This can be achieved by using the recent remote sensing technologies, which allow to systematically monitor wide areas without the need of maintaining ground networks. In particular, for satellite precipitation estimation, both the top-down and bottom-up approaches have been exploited in recent years to obtain information related to rainfall. Both the methodologies carry advantages and limitations. Their merging, coupled with high spatial resolution ancillary information, is therefore recommended to reach the final aim of detailed and accurate precipitation data.In this study, the rainfall data obtained from IMERG Late Run and SM2RAIN ASCAT (H SAF) are downscaled and merged over the whole Europe. The downscaling is obtained by leveraging high spatial resolution statistical information from CHELSA product, while a triple collocation technique is applied to merge the two downscaled datasets. The resulting high resolution rainfall is subsequently compared against multiple products, including coarse resolution ones such as H SAF, IMERG-LR, ERA5, EOBS, PERSIANN, CHIRP, GSMAP, and high-resolution products like EMO, INCA, SAIH, COMEPHORE, MCM, 4DMED. These comparisons, spanning ground, model and satellite data, serve to assess its capabilities in estimating precipitation over Europe.
How cloud droplet number concentration impacts liquid water path and precipitation in marine stratocumulus clouds - a satellite-based analysis using explainable machine learning
Authors: Zipfel Lukas , Andersen Hendrik , Cermak Jan , Grosvenor Daniel P.
Published: March 2024

In this work, a data set comprised of satellite observations and reanalysis data is used in explainable machine learning models to analyse the relationship between the cloud droplet number concentration (Nd), cloud liquid water path (LWP) and the fraction of precipitating clouds (PF) in 5 distinct marine stratocumulus (MSC) regions.Aerosol--cloud--precipitation interactions (ACI) are a known major cause of uncertainties in simulations of the future climate. An improved understanding of the in-cloud feedback processes accompanying ACI could help in advancing their implementation in global climate models. This is especially the case for marine stratocumulus clouds which constitute the most common cloud type globally.The machine learning framework applied here makes use of Shapley additive explanation (SHAP) values, allowing to isolate the impact of Nd from other confounding factors which proved to be very difficult in previous satellite based studies.All examined MSC regions display a decrease of PF and an increase in LWP with increasing Nd, despite marked inter-regional differences in the distribution of Nd. The negative Nd-PF relationship is stronger in high LWP conditions, while the positive Nd-LWP relationship is amplified in precipitating clouds. While these results for the Nd-LWP relationship differ from the findings in recent satellite-based global analyses, they are consistent with previous studies using model simulations. The results presented here indicate that precipitation suppression plays an important role in MSC adjusting to aerosol-driven perturbations in Nd.
Modelled outdoor temperature effects and heat-related mortality impact of cool roofs and rooftop photovoltaics in London
Authors: Simpson Charles H. , Brousse Oscar , Davies Michael , Heaviside Clare
Published: March 2024

Population exposure to high temperatures poses health risks and increases mortality, but comprehensive studies comparing impacts of building and street levels interventions on air temperature at urban scales are still lacking. High-albedo roofs (also called “cool roofs”) can lower the air temperature in urban areas, compared to standard low-albedo roofs. As part of the transition to renewable power generation rooftop regional authorities in the UK have set targets for rooftop solar panel capacity, but some recent studies have argued that solar panels may increase urban temperatures and therefore have unintended consequences. Using advanced urban climate modelling (WRF BEP-BEM), we model the impact of these cool roofs and rooftop photovoltaics on urban air temperature during the record-breaking hot summer of 2018, and estimate the impact these measures may have on heat-related mortality.We find that cool roofs and rooftop photovoltaics both decrease modelled daily-mean temperature compared to standard low-albedo roofs. Rooftop photovoltaics may reduce heat-related mortality by 96 (12%), or cool roofs by 249 (33%), in scenarios where all roofs have these measures. Monetised using value of statistical life, we estimate benefits for solar roofs and cool roofs of £237M and £616M respectively for London July-August 2018 conditions, and we estimate 20 TWh of electricity, worth £3-6 billion, would be generated in the rooftop PV scenario. Our modelling indicates that, in the conditions of London July-August 2018, rooftop PV or cool roofs may reduce near-surface air temperatures and therefore heat related mortality, with cool roofs having a larger effect.
Atmospheric hydrogen budget: an evaluation using chemistry-transport models and a box model
Authors: Krishnan Srinath
Published: March 2024

Hydrogen fuel, a green transition option and a cleaner alternative to fossil fuels, has an indirect greenhouse impact through atmospheric reactions of “leaked” hydrogen. Sand et al., 2023 used six different chemistry-transport models (CTM) to estimate a Global Warming Potential over a 100-year time horizon (GWP-100) for hydrogen of 11.6 ± 2.8, in range with similar studies. In this study, we extend those analyses by investigating the atmospheric production and loss terms of hydrogen in the CTMs. Specifically, we compare formaldehyde (HCHO) and the hydroxyl radical (OH) concentrations. Then we develop a box model that can be used for quickly evaluating the impact of the different sources and sinks on atmospheric concentration and isotopic composition of H2 from a global perspective.Atmospheric production of hydrogen through photo-oxidation of methane and volatile organic compounds represents roughly 60% of the total production. To compare the atmospheric production in the models, we evaluate HCHO (produced during photo-oxidation). A preliminary comparison between the global mean model-derived tropospheric HCHO and TROPOMI-derived HCHO suggests that all models other than WACCM perform reasonably well. Generally, models tend to overestimate HCHO values over land and underestimate HCHO concentrations over the oceans. WACCM has very low HCHO values compared to TROPOMI and the other models.The two primary removal mechanisms are soil uptake (65-85%), and atmospheric oxidation by hydroxyl radical (OH). Among the models, OsloCTM3 and WACCM have higher OH concentrations compared to GFDL, INCA and UKCA. Direct measurements of atmospheric OH concentrations are lacking due to the short lifetime of the OH radical. Therefore, we used CO and NO2 concentrations as a proxy to evaluate the models. Compared to satellite values (TROPOMI for NO2 and MOPPIT for CO), models seem to generally overestimate NO2 and underestimate CO. These results are discussed within the context of the OH radical and atmospheric lifetime of H2.Then we present a simple box model that is developed using CTM results for studying the atmospheric budget of H2. Reconstructions of hydrogen concentrations using ice-core records from the South Pole over the last 150 years show an increase in H2 concentration of ~200ppb, likely due to increased methane oxidation and anthropogenic emissions. We use time-varying emissions in our box model to replicate this time evolution since the pre-industrial period.The box model also contains a framework for studying hydrogen isotopic composition. Each of the sources and removal processes of H2 have distinct isotopic signatures. This allows for the evaluation of concurrent changes in atmospheric concentrations and hydrogen isotopic compositions for each source/sink contribution, leading to a more robust evaluation of the hydrogen budget in the atmosphere.
Ice Fabric on Thwaites Glacier from ApRES Polarimetric Measurements
Authors: Case Elizabeth , Kingslake Jonny
Published: March 2024

Thwaites Glacier (TG) is a wide, fast moving ice stream that, along with Pine Island Glacier, drains much of the West Antarctic Ice Sheet (WAIS). This work presents preliminary results of ice fabric, bed topography, and englacial layering from a 200-km-long Autonomous phase-sensitive Radio Echo Sounder (ApRES) survey along the trunk of TG as part of the International Thwaites Glacier Consortium’s GHOST project in 2022-2023. From 235 point measurements and 47 polarimetric measurements, we find a variable, complex ice fabric that changes in strength and orientation along the transect and with depth. Fabric strength, measured as horizontal anisotropy, is on average stronger downstream than upstream, and the fast axis (also known as the symmetry axis) is more aligned along flow than across, as expected in an ice stream. Ice fabric is useful to both meaure and model because it both serves as a record of past stress and deformation, and affects viscosity, directionally softening the ice and impacting the glacier’s response to future stresses.