bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards 3D attenuation tomography of the Northern Chile forearc
Authors: Castro-Melgar Ignacio , Sippl Christian
Published: March 2024

In subduction zones, intermediate-depth earthquakes typically occur in two discrete layers, delineating an upper and a lower seismicity plane with a separating aseismic or minimally seismic region, a phenomenon named Double Seismic Zone (DSZ). However, the seismicity pattern in Northern Chile features two parallel planes of seismic activity only in the shallower section of the slab. Around depths of 80–90 km, the seismicity undergoes a transition to a significantly seismogenic zone approximately 25–30 km thick, effectively connecting the initial seismicity planes. This variation presents a distinct form of intraslab seismicity that deviates from the traditional DSZ structure and prompts further investigation into its underlying mechanisms and implications for regional seismic hazard assessment. Insights derived from this region's seismicity could provide pivotal constraints and enhance our understanding of the complex interplay between geological processes, mineral transformations, and fluid migrations in shaping subduction zone seismicity.The attenuation of seismic waves in a rock volume is a property that is highly sensitive to the presence and concentration of fluids as well as spatial variations of temperature. As intermediate-depth seismicity is thought to originate from dehydration processes in the downgoing slab, along-strike or along-dip changes in slab seismicity should have a signature in seismic attenuation of the slab as well as the overlying mantle wedge. We hence aim at better understanding the aforementioned seismicity configuration in Northern Chile by acquiring a 3D image of its attenuation signature. The primary dataset for our analysis comes from the seismic stations of the Integrated Plate boundary Observatory Chile (IPOC) network in Northern Chile's forearc, augmented by additional data from different temporary deployments. Using the extensive seismicity catalog of Sippl et al. (2023), we have about 180,000 events at over 50 seismic stations at our disposal from the period 2007 to 2021; we select only the high quality traces for the analysis. The rays are traced in a 3D velocity model. We invert the spectral ratios obtained with the coda normalization method to obtain total-Q values. We present images of the 3D attenuation structure of the Northern Chile Forearc between 21ºS and 23ºS, which are obtained with measurements of the coda normalization method using the Multi-Resolution Attenuation Tomography algorithm (Sketsiou et al., 2021).
Exploring drivers of change in the Ross Sea with a regional ocean model
Authors: Mountford Alethea S. , Bull Christopher Y. S. , Jenkins Adrian , Jourdain Nicolas C. , Mathiot Pierre
Published: March 2024

The Ross Sea and Ross Ice Shelf have remained relatively unchanged over recent decades, despite increasing global anthropogenic influences, and ocean temperatures and ice shelf melt rates increasing nearby. Future atmospheric warming, for example, could lead to a transition of the sub-ice shelf cavity from its current cold state to a warm state, which could in turn result in a dramatic increase to the currently low basal melt rates in the Ross Ice Shelf. We present a regional ocean model configuration (NEMO) at 1/4° resolution, which encompasses the whole of the Ross Sea, Ross Gyre and Ross Ice Shelf, as well as eastwards to include the Amundsen Sea, with a series of perturbation experiments to near-surface air temperature (an increase of 10°C) and precipitation (an increase by a factor of two) and a combination of the two. The model includes static ice shelves, extending from Merz to Venable, and their thermodynamic interaction with the ocean. Perturbations to the air temperature and precipitation alone are not sufficient to significantly alter the circulation or oceanographic conditions within the Ross Sea or within the cavity of the Ross Ice Shelf. However, when both perturbations are applied simultaneously, waters within the Ross Ice Shelf cavity warm to over 1°C, inducing an increase in basal melt of around 1000 Gt/yr within the cavity over the course of the simulated period 2017-2100. We see an increase in the strength of the Ross Gyre, with an eastward extension of the gyre into the Amundsen Sea. Circulation within the cavity is also affected, with a visible reduction in the outflow of waters from the cavity. Oceanographic changes within the cavity and the Ross Sea could have an effect on deep water formation and wider reaching impacts on global circulation.
Predicting petrophysical properties from hyperspectral borehole data
Authors: Kamath Akshay , Kirsch Moritz , Thiele Samuel , Gloaguen Richard
Published: March 2024

Recent research has highlighted significant correlations between hyperspectral data and the petrophysical properties of geological formations. Petrophysics acts as the link between geology and geophysics, and is crucial for constraining geophysical inversions, regional characterisation and mineral exploration. In this study, we employ various machine learning methods to predict P-Wave velocities using hyperspectral borehole data, with a focus on cross-validation between different boreholes in the same region. Our dataset includes 4022 paired observations of P-wave velocities, obtained from downhole sonic logging in one borehole, and corresponding hyperspectral data spanning visible-near (380–970 nm), shortwave (970–2500 nm), midwave (2700–5300 nm), and long-wave (7700–12300 nm) spectra, averaged over a 10 cm x 5 cm area. We utilised principal component analysis (PCA) for dimensionality reduction. The initial PCA stage extracted 10 principal components from each sensor type, which were then integrated. A subsequent PCA stage was conducted to reduce inter-sensor correlation, yielding 10 composite features that represent the variability across the complete VNIR-LWIR spectrum.To validate our model, we conducted tests using 1160 pairs of analogous measurements from a different borehole within the same geological region. The model demonstrated impressive predictive capabilities, particularly with Support Vector Regression (SVR) and Artificial Neural Networks (ANN). The test set yielded R2 scores of 0.758 for SVR and 0.811 for ANN, indicating strong predictive accuracy. Building upon this success, our future work will expand the scope of prediction to include various other petrophysical properties critical to geophysical characterization and mineral exploration, such as S-Wave velocity, magnetic susceptibility, and rock density, properties which are critical for geophysical characterization and mineral exploration.
On the causes of melt focusing at mid-ocean ridges: Ridge suction versus permeability barrier
Authors: Lu Gang , Huismans Ritske , May Dave
Published: March 2024

Emplacement of magmatic crust at mid-ocean ridges (MORs) is confined in a narrow neovolcanic zone on the seafloor, whereas geophysical observations suggest that mantle melting occurs over a broad region. How melt is transported horizontally towards the ridge axis, i.e. melt focusing, remains incompletely understood. Here we present numerical models, theoretical decomposition, and scaling analysis, to isolate melt focusing mechanisms, and focus in particular on ridge suction and on the permeability barrier. We show that shear deformation induced dynamic pressure leads to large decompaction pressure, which increases porosity, instead of generating ridge suction as previously expected. We further demonstrate that a permeability barrier resulting from cold lithosphere systematically leads to a horizontal compaction pressure gradient that focuses melt toward the ridge axis, which may explain widespread melt focusing at global MORs as well as the three-dimensional melt distribution at ultra-slow spreading centers.
Evaluating the environmental sensitivity to land degradation: a case study in central Taiwan
Authors: Wang Yung-Chieh , Lu Yu-Hsin
Published: March 2024

Land degradation is a primary form of global environmental deterioration. Soil erosion and land desertification are common land degradation processes in many regions. In this research, we take the Zhuoshui River basin in central Taiwan as the study area, and investigate the environmental sensitivity of different land use/land cover to land degradation subjected to historical and future climate scenarios. In order to understand the quality of land resources in the study area, we used the evaluating framework of the Mediterranean Desertification and Land Use (MEADALUS) model with revisions according to the localized mountainous characteristics in central Taiwan, and calculated the Environmentally Sensitive Areas Index (ESAI) of the study area. The ESAI is comprised of five indicators, which include climate, soil, vegetation, management, and landslide indicators. For the climate index, observed data from 2001 to 2020 of weather factors were used in the historical scenarios. On the other hand, data of weather factors generated by MIRCO5 GCM considering RCP2.6 and RCP8.5 scenarios in near-term and long-term time scales were used for the climate indicator in the future scenarios. The results depict the spatial variation of environmental sensitivity to land degradation in the Zhuoshui River basin using numerical values ranging from 1 to 2, where higher values correspond to more severe degradation. It is evident that the upper reaches of the Zhuoshui River exhibit lower degrees of land degradation due to dense vegetation, higher elevations, and limited human presence. In contrast, the downstream areas show a higher trend of land degradation, with the wet season exhibiting lower degradation trends compared to the dry season. Furthermore, there is a slight upward trend in land degradation since 2015, primarily attributed to climate indicators, as soil and vegetation indicators, as well as anthropogenic management indicators, show no significant changes. The land degradation index shows relatively subtle differences between future scenarios and historical scenarios, with land degradation index variations ranging from -13% to 22%. Negative values in the degradation index differences indicate an improvement in the degree of degradation, while positive differences denote an exacerbation of land degradation. According to the land use distribution in the Zhuoshui River basin, the land degradation trends for forests and national parks show relatively consistent variations between the dry and wet seasons. However, in the middle and lower reaches of the basin, apart from the RCP85 scenario for the long-term period, the other three scenarios exhibit higher differences in land degradation index changes for agricultural and urban areas compared to historical values. The research provides a reference for preventing continued land degradation and conserving terrestrial ecosystems and biodiversity in the study area.
Ultrasonic Evaluation of Shales vis-à-vis Temperature: A Case Study from Permian Damodar Valley Basin
Authors: Jamwal Varun Dev , Sharma Ravi
Published: March 2024

Despite constituting two-thirds of the sedimentary rock volume, shales are a few of the least understood rocks. The varied depositional processes and environments give rise to complexity and anisotropy in them. Understanding unconventional resources like shales becomes crucial given their abundance in the petroleum systems and reservoirs and their potential suitability for sub-surface carbon and radioactive waste storage. Therefore, paramount significance lies in understanding the petrophysical and rock physical characteristics of shales to develop feasibility models for the sustainable use of these rock types. This investigation focuses on the Barren Measures and Raniganj Formation shales in the Damodar Valley of Eastern India, which are primarily rich in clays, carbon, and iron and are of fluvio-lacustrine origin. These relatively shallow formations can be good sites for storage and sequestration as they are overlain by shaley and clayey formations acting as traps. The anisotropy in shales is even more challenging as its imponderables range from a micro to a macro scale. This changes even further with factors like organic-hosted porosity and maturity. The inherent anisotropy in shales necessitates a multiscale examination. These multiscale discontinuities, coupled with parameters like organic matter and maturity, impact the elastic properties of the rocks, as evidenced by the ultrasonic evaluations. In this study, acoustic characterization of samples was conducted using a benchtop ultrasonic wave propagation setup. The samples were clustered based on their colour and observed megascopic properties. Some sandstones were also included in the study to contrast sandstones with respect to shales. The wave velocities were determined for samples subjected to progressive heating up to 200°C (gas window), and the consecutive changes in the elastic parameters and resultant wave velocities of the rock were studied. Inputs from other methods utilizing different physics, such as FE-SEM, XRD were integrated to refine our interpretation. Notable changes were seen in wave velocities, especially in clusters with elevated organic content, while the density and Vp cross plots gave a good correlation with an R2 value of around 0.7.This study advances our understanding of the impact of temperature on the elastic properties of shales, an aspect less explored than factors like stress and pressure. Thoroughly characterizing these parameters through acoustic methods provides critical insights into shale's storage capacity, carbon sequestration potential, and additional hydrocarbon recovery, specifically with respect to the Damodar Valley shales, aiding India to offset the projected peak of 4 GT CO2 emissions to achieve the carbon neutral goal promised at COP 26 and fulfilling UN Sustainable Development Goals.
Experimental Design for Seismic Mass Movement Monitoring
Authors: Strutz Dominik , Kiers Tjeerd , Schmelzbach Cedric , Maurer Hansruedi , Curtis Andrew
Published: March 2024

Mass movements are a significant natural hazard and are expected to increase in frequency as global temperatures rise and extreme weather events become more common. The close observation of mass movements can be essential to minimise their adverse effects on society. The efficient use of the available surveying equipment and resources is important when monitoring mass movements. This is because they are often located in inaccessible terrain, and observing them over months or years can be expensive.A deployment pattern and number of sensors (henceforth, the experimental design) can often be optimised to substantially decrease the uncertainty of scientific results that can be inferred from the observed data. We have developed a novel method to optimise the design of seismic node layouts and fibre-optic based Distributed Acoustic Sensor (DAS) cable pathways for monitoring seismic events. We use it to design surveys to focus on slope instability-induced seismicity.Our general Bayesian experimental design framework can take into account prior information on event locations, subsurface seismic velocity models, the nonlinearity of the physics governing seismic traveltimes, different models of attenuation, and the directional sensitivity of different sensor types (e.g. the inline sensitivity of fibre-optic cables). The introduction of a likelihood that a travel-time measurement will be made at a given station for a given seismic event allows us to account for the effect of attenuation on the observed data, and the angular dependence of one-component measurements such as DAS.We show that we can efficiently design seismic node installations, give quantitative recommendations for DAS cable layouts, and show the feasibility of optimising hybrid designs combining both measurement types. We benchmark the experimental design algorithms using an effectively exhaustive data set collected at the Cuolm da Vi slope instability (Swiss Alps, near Sedrun, in Central Switzerland). The data set includes recordings from over 1000 seismic nodes, in a hexagonal grid with roughly 28m receiver spacing over the slope’s surface, of which each recorded data from over 100 dynamite shots spread across the slope. This extremely dense deployment provides the unique opportunity to choose nearly arbitrary designs (i.e. subsets of the nodes) and then test those designs by using them to locate the explosions for which we know the location. By averaging the performance of the probabilistic source location inversions over all dynamite shots, the performance of optimised, heuristic and random experimental designs can be compared.The same design methods can be applied to seismic source localisation in many different contexts, such as locating microseismic events, and other scenarios, such as infrasound source location.
Towards a 3D integrated geophysical model of Northern Chile
Authors: Godová Dominika , Sippl Christian
Published: March 2024

The South American active margin is one of the most important and well-studied subduction zones on the Earth. In the last decade, our knowledge about the geometry of its respective constituent parts in Northern Chile has been significantly expanded thanks to seismicity data from a large network of permanent seismic stations. That calls for an effort to summarize these diverse constraints in a single 3D model, which can be validated and optimized using satellite gravity data.Integrated geophysical modelling is primarily based on gravity data, which bring information about different crustal density inhomogeneities and their sources. As an inverse geophysical problem, gravity modelling is ambiguous, and therefore it is necessary to include geometry constraints from other geophysical data as well as geological information. Different types of seismic data offer the most commonly used constraints due to their depth range and the relatively well-described relation between seismic velocities and densities.We aim to compile a 3D integrated geophysical model for Northern Chile in the IGMAS+ software, based on gravity data of the global gravitational (or geopotential) model EIGEN-6C4, which include terrestrial, satellite and altimetry data to a high degree and order of spherical harmonic expansion. As the main geometry constraints of the model, we use the newest available seismicity catalogs in the study area together with crustal thickness values from receiver functions. Starting with the geometries of previously published density models in the area of the Central Andes, especially those located at least partly in Northern Chile, we will modify these models guided by the geometry constraints from seismic data and will also use regional and global models of crustal and lithospheric interfaces, such as the top of basement in sedimentary areas, plate interface geometry, depth to continental Moho, and the lithosphere-asthenosphere boundary (LAB). Densities of the modeled bodies will be selected based on previously published models or estimated from seismic velocities. We also plan to study the gravity effect of the different geometries deduced from different generations of seismic data.Our contribution provides an overview of evidence compiled in previous studies and adds new information on the deep lithospheric structure of the North Chilean margin by integrating them into a single model.
Towards improved prediction of compound heat and drought extremes by CWRF downscaling
Authors: Zhang Shulei , Zhang Han
Published: March 2024

Given their profound socio-economic impact and increasing occurrence, compound heat and drought extremes (CHDEs) have become a focal point of widespread concern. Numerous studies have attempted to reproduce and predict these extremes using general circulation models (GCMs); however, the performance of these models in capturing extreme events remains controversial. This study presents an improved historical simulation of CHDEs over China by using the regional Climate-Weather Research and Forecasting model (CWRF) to downscale the projections of two GCMs that participated in the Coupled Model Intercomparison Project Phase 6. The CWRF downscaling improved GCMs in capturing the thresholds of extreme hot and extreme dry conditions and demonstrates a better agreement with observations in the temporal trends and spatial patterns of extreme heat and extreme drought events. The performance of CWRF downscaling to reproduce CHDEs also surpasses that of GCMs, with an even greater enhancement compared to univariate extreme events. The improvement is particularly pronounced in sub-humid areas, which is primarily attributed to the enhanced simulation of temperature-precipitation coupling relationships by CWRF downscaling. This superiority is found to be associated with the finer land surface processes and land-atmosphere interaction processes of CWRF. This study highlights the important role of land-atmosphere interactions in shaping CHDEs and the efficacy of using regional climate models to reduce uncertainty in extreme event simulations.
Improving Carbon Sequestration and Yield of Barley (Hordeum vulgare) through Combined Application of Green Manure and Mineral Fertilizers under Cambisols in Ethiopian Highlands
Authors: Debele Gebreyes Gurmu , Kassie Kenzemed , Getachew Tsegaye
Published: March 2024

ABSTRACT Nowadays, due to high population pressure more fragile lands are put into farming which then leads to low crop yield, loss of biodiversity and above all contributing to increased greenhouse gas emissions. This two year study (2020-2021) evaluated the potential of legume green manure (GM) species in improving soil fertility and barley yield, and their ability to effectively sequester soil organic carbon (SOC) towards reducing greenhouse gas emissions. The GM crops; lupine and vetch were planted during the main rainy season on the land that previous barley crop was harvested and left bare and fallow. The green manures crops were chopped and ploughed under at their 50% flowering stage and the main test crop, barley was introduced during the next cropping season. The treatments included (i) vetch GM, (ii) vetch GM + 23N + 20P, (iii) lupine GM, (iv) lupine GM + 23N + 20P, (v) fallow, (vi) fallow + 46N + 20P laid down in RCBD design with three replications. The N rate used was half when integrated with the GM species but full dose with the fallow system, whereas P was full dose. Results showed that barley grain & biomass yields were increased by 3.7 to 39.8% and 10.66 to 38.58%, respectively due to the application of the GM crops. The highest grain yield (4.1 t ha-1) and biomass yield (10.1 t ha-1) were recorded from vetch + NP application while the least grain yield (2.94 t ha-1) & biomass yield (7.24 t ha-1) were registered from the traditional fallow system. Green manure addition has brought 25 to 95.41% SOC relative change in the top 0-20cm soil depth compared with the traditional fallow system. Since both GM species are legumes, they added more N to the soil alongside with storing more C in the soil so that C: N ratio was also not affected. The highest carbon sequestered was from sole application of vetch GM (26.18 t C ha-1 yr-1) followed by vetch + NP applications (22.82 t C ha-1 yr-1). Lupine GM alone sequestered 9.24 t C ha-1 yr-1 and lupine + NP sequestered 6.86 t C ha-1 yr-1. The carbon balance in the fallow and fallow + NP combinations were negative (-0.98 and -1.40 t C ha-1 yr-1, respectively) indicating that there was C loss to the atmosphere. Therefore, application of vetch and lupine GMs with and/or without inorganic fertilizer integration had positively contributed towards improving the yield of barley and sequestering more C as compared to the local fallow practice.
Progress report on Beyond EPICA – oldest ice (BE-OI) Little Dome C (LDC) activity
Authors: Wilhelms Frank ,   LDC field parties 2022/2023 & 2023/2024, drill & science workpackage, stable isotope field measurements group
Published: March 2024

The European Project for Ice Coring in Antarctica (EPICA) Beyond EPICA – oldest ice aims at retrieving a continuous ice core record of climate feedback and forcing spanning about 1.5 Ma back in time. After determining a suitable drill-site LDC during an extensive pre-site survey 35 km southwest of Concordia station, we are in the second deep drilling season. At the time of submission of this abstract, we penetrated beyond 1604.92 m, roughly spanning one glacial-interglacial cycle. We will report on the drilling and core processing activities and verify the prognostic age scale by comparison with dielectric profiling (DEP) and stable isotope saw dust measurements in the field.
Integrating Data-Driven Techniques for Assessing Urban Air Quality Dynamics
Authors: Fajardo Fajardo Dario , Chávez Erick , Narváez Cristhian
Published: March 2024

As a strategy to improve environmental quality, air pollution, and its impact on health, monitoring systems for emissions and environmental variables have been proposed. These systems provide information on air pollution levels in areas of interest and serve as support for analyzing the state of the environment. This enables the assessment of effects on human health and quality of life. A model is designed and implemented to estimate pollutant gases, air quality, and meteorological variables in a city using scattered local measurements and information from remote measurements provided by various sources. These are associated and processed to determine relevant information that helps generate accurate estimation models and their visualization through pollution maps. Meteorological data, gas, particulate matter, local energy consumption, and on-site measurements across the city, involving pedestrians and cyclists, contribute to environmental characterization studies, they can make use of a low-power, wide-range LoRa communication network. Using inference from a lower-resolution grid, maps are interpolated to resolutions of 50m or 100m. The kriging method is then applied to enhance the resolution to 5.5m, utilizing a geostatistical model based on the variance and covariance of the samples to model the variance at a lower resolution. Finally, machine learning algorithms are employed to model and visualize data, generating pollution maps and environmental variables to understand pollution dynamics.
 
A novel rapid cooling assembly design in a high-pressure Cubic Press apparatus
Authors: Xu Yongjiang , Wu Peiyan , Lin Yanhao
Published: March 2024

In traditional high pressure-temperature assembly design, priority has been given to temperature insulation and retention at high pressures. This limits the efficiency of cooling samples at the end of experiments, negatively impacting many studies in the field of high-pressure earth and planetary science. Inefficient cooling of experiments containing molten phases at high temperature leads to the formation of quench textures, which makes it impossible to quantify key compositional parameters of the original molten phase, such as their volatile contents.Here, we designed a novel, low-cost experimental assembly for rapid cooling in a six-anvil cubic press. This assembly not only retains high heating efficiency and thermal insulation, but also enables a very high cooling rate (~600 °C/s from 1900 °C to the glass transition temperature). Without using expensive materials or external modification of the press, the cooling rate in an assembly (~600 °C/s) with cube lengths of 38.5 mm is about ten times faster than the traditional assembly (~60 °C/s). Experiments have shown that the heterogeneous quenched textures produced with the traditional assembly, does not shown with the novel rapid cooling assembly design.
Can landslides provide geosystem services?
Authors: Mergili Martin , Bauer Christian , Kellerer-Pirklbauer-Eulenstein Andreas , Petermann Jana , Pfeffer Hanna , Robl Jörg , Schröder Andreas
Published: March 2024

The concepts of biodiversity and ecosystem services, focusing on the diversity of life and the services provided to humans by such diversity, in interaction with abiotic ecosystem components, are well established. Only recently, geosciences have started to challenge this rather biocentric view by highlighting that geodiversity – understood as the diversity of minerals, rocks, geological structures, soils, landforms, and hydrological conditions – provides substantial services to society and should be treated as equal partner to biodiversity. It was proposed to use the more general term natural services or, where geodiversity is much more relevant than biodiversity, geosystem services. Even though the term geosystem services is more and more employed in literature, it evolves only slowly into a commonly used concept with a clearly defined meaning. Interpretations range from all services associated with geodiversity which are independent of interactions with biotic nature, to the restriction to subsurface services. None or few of these concepts, however, include risks as negative services, or as costs of services, which is surprising as this would enable a more integrated vision on human-nature relationships. Only very recently, the potential of geosystem service maps to highlight both services and risks related to geomorphological processes was pointed out.This work picks up landslides as a type of geomorphological process and landform, which is rather negatively connotated in society and associated with risks rather than with chances. We use landslides to develop a broader understanding of geosystem services, together with the common understanding of hazards and risks. We will (i) present a sound and integrated conceptual framework to consider landslides within the field of tension between risks and resources, and (ii) highlight a case study where landslides are used as cultural geosystem services for environmental education in the context of UNESCO Global Geoparks, which are considered important instruments for conserving and promoting geodiversity.
A challenge to the Regolith Hypothesis for the MPT from present day sediment distribution and coupled climate-ice-sediment physics
Authors: Drew Matthew , Gosse John , Tarasov Lev
Published: March 2024

The mid-Pleistocene Transition (MPT) from 41 kyr to 100 kyr glacial cycles occurred in the absence of a change in orbital forcing. This presents a challenge for the Milankovitch theory of glacial cycles. A change from a low to high friction bed under the North American Ice Complex through the removal of pre-glacial regolith is hypothesized to play a critical role in crossing the threshold to longer and stronger glaciations. However, testing this Regolith Hypothesis requires constraint on currently unknown pre-glacial regolith cover as well as assessing whether glacial sediment processes remove the appropriate amount of regolith to enable glacial system change consistent with the MPT. Pleistocene regolith removal has not yet been simulated for a realistic, 3D North American ice sheet fully considering basal processes. Constraints on pre-glacial bed elevation and sediment thickness are sparse and the bounds are wide.What limits on pre-glacial regolith thickness in North America can be inferred from our current understanding of glacial processes and the present-day distribution of unconsolidated sediment? How does pre-glacial sediment thickness influence the evolution of Pleistocene glacial cycles? We answer these questions with an ensemble of whole-Pleistocene simulations with high-variance parametrizations and range of pre-glacial regolith thicknesses.We use the 3D Glacial Systems Model which incorporates the relevant glacial processes: 3D thermomechanically coupled hybrid SIA/SSA ice physics, fully coupled sediment production and transport, subglacial linked-cavity and tunnel hydrology, isostatic adjustment from dynamic loading and erosion, and climate from a 2D non-linear energy balance model and glacial index. This fully coupled system is driven only by atmospheric CO2 and insolation. The model captures the Pleistocene evolution of North American glaciation: 41 to 100 kyr glacial cycles shift, similar latitudinal extent in the early and late Pleistocene, LGM ice volume, deglacial ice margin chronology, and the broad present-day sediment distribution within the parametric and observational uncertainty. Constrained by large scale reconstructions of present-day surface sediment distribution, regional sediment distribution estimates, and regional bedrock erosion estimates, these results bound the mean pre-glacial sediment thickness.Our results suggest thin (
A model to estimate the L-band amplitude scintillation index from Swarm: the outer scale length assumption
Authors: Imam Rayan , Zheng Yuhao , Spogli Luca , Alfonsi Lucilla , Cesaroni Claudio , Xiong Chao , Jin Yaqi , Clausen Lasse B. N. , Wood Alan , Miloch Wojciech J.
Published: March 2024

Irregularities in the plasma density in the ionosphere affect trans-ionospheric radio signals, resulting in fluctuations in the amplitude and phase of these signals, known as amplitude and phase scintillations. We recently developed a model that relies on ESA’s Swarm constellation to estimate the amplitude scintillation index (S4), representing the plasma density irregularities affecting the L-band Global Navigation Satellite Systems (GNSS) signals. One of the main challenges for this model is the need for estimates/measurements of the outer scale length which, for operational considerations, must be available to the model independent of ground measurements as much as possible. In this paper, we show how this challenge was addressed.In particular, we rely on the combined measurements from ionosondes, GNSS scintillation monitoring receivers, Swarm 16 Hz faceplate instrument, and Rino’s formula for weak scattering scenario to solve for the outer scale wave number. Then, we develop a climatological map for the outer scale wavenumber to be utilized by the Swarm S4 model.To achieve this, we rely on conjunctions between Swarm satellites trajectories and GNSS signals paths over locations with co-located ionosondes and ionospheric monitoring GNSS scintillation receivers. We rely on models and assumptions to simplify the equations and to translate the different instruments’ measurements into their equivalent values at the phase screen height (hmF2) assumed by Rino’s formula. We detail the methodology and show the results. The outer scale length has been finally sorted into climatological in magnetic coordinates under different space weather conditions.
CO2 storage in saline aquifers: multi-scale processes visualized using the Sleipner case
Authors: Yun Tae Kwon , Macut Mateja , Schulze Katja , Ringrose Philip , Berg Carl Fredrik
Published: March 2024

Injection of dense-phase CO2 in a saline sandstone aquifer involves several processes which ideally work together to ensure effective long-term storage. The main processes are flow of free-phase CO2 (controlled by viscous and gravity forces), residual trapping at the pore scale, structural trapping at the scale of geological heterogeneities and dissolution in the aqueous phase.  Assessment of possible lateral and vertical migration along high-permeability layers or faults and fractures will also require stress-sensitive flow models which consider the phase behaviour of CO2, and the associated coupled thermal-hydraulic-mechanical-chemical processes.Many insights into these complex processes can be obtained by analysis of the time-lapse seismic data at Sleipner CO2 storage project in Norway, in conjunction with findings derived from the quantitative and qualitative uncertainty analysis of the medium-scale flow experiments at the Mont Terri Rock Laboratory (Switzerland), involving periodic injections over long-term (CO2LPIE). The insights at Sleipner include the effects of internal shale layers and shale breaks in controlling the actual multi-layer CO2 distributions, the likely contribution of different of trapping mechanisms and the effectiveness of the overlying caprock. Another set of insights gained from these data are estimates of the effective use of the pore space at different length scales. The seismic imaging datasets can be used to show that at the scale of whole storage unit the overall storage efficiency is in the range of 2-5%, with the result depending very much on how the storage volume is defined. When the effects of areal and vertical sweep efficiency are considered, the fraction of the pore space occupied by CO2 rises to around 40-50%.We illustrate these multi-scale processes using seismic data, analytical analysis, example flow models and 3D/4D visualization. Use of Invasion Percolation (IP) flow models is contrasted with multiphase (finite difference) flow simulators. With this approach CO2 migration problems will be addressed, as well as various open-source research codes will be used to develop enhancements for handling fluid mixing between hydrocarbon and CO2 phases in brine-saturated media. Moreover, coupled thermal modelling is found to be important at this site due to significant temperature changes as the CO2 plume expands and rises within the formation. Next to classic PC screen display, we empower the visualization by using the extended reality (XR) platform for geoscience, BaselineZ. This allows for true 3D (holographic) display in virtual reality (VR) as well as remote and interactive collaboration around the Sleipner dataset and thus leads to new insights. 
Study of the Urban Heat Island effect in Cyprus by using Earth Observation 
Authors: Soderiades Charalambos , Tryfonos Kyriacos , Michaelides Silas , Agapiou Athos , Hadjimitsis Diofantos
Published: March 2024

Urbanization activities and their effects in Cyprus are more pronounced in the last 35 years, leading to a drastic change of the local climate of Cyprus’ main cities. Indeed, the contrast of energy absorption between developed urban areas and surrounding rural areas results in a variation of the local climate. The monitoring of the Urban Heat Island (UHI) is essential in the effort to produce heat maps of the urban area of Limassol, a town on the south coast of Cyprus. The area affected by UHI must be examined systematically in order to extract information that is vital in assisting decision- and policy-makers to adopt effective mitigation strategies and improve urban planning. This study presents the findings from the literature review of studying the UHI using earth observation, and reports on the results of the UHI effects for the whole Cyprus area, by using Landsat-5/8 TM & Sentinel-3 satellite images. NDVI calculations were conducted to derive the Fraction of Vegetation (FV) and calculate Emissivity over the last 20 years (2003-2023). Urban heat Island determination between several cities in Cyprus is presented in this study.  The results of this study are intended for use by the local authorities in support of the proposed revision of the local plans for the area by proposing a new ‘sustainability index‘ that uses UHI for urban planning purposes.
Capabilities of the wave telescope for multi-scale spacecraft configurations using a Vlasiator simulation
Authors: Schulz Leonard , Plaschke Ferdinand , Glassmeier Karl-Heinz , Motschmann Uwe , Narita Yasuhito , Palmroth Minna , Roberts Owen , Turc Lucile
Published: March 2024

We present an analysis of the wave properties in Earth's foreshock and dayside magnetosphere in a Vlasiator global magnetospheric simulation, using the wave telescope analysis technique. Vlasiator is a Hybrid-Vlasov plasma simulation and treats electrons as a fluid while protons are described by distribution functions. In anticipation of future multi-scale spacecraft space plasma missions such as HelioSwarm or the proposed Plasma Observatory, artificial spacecraft constellations consisting of more than 4 satellites have been used to measure the electromagnetic field and plasma properties in the Vlasiator run. Using the wave telescope analysis technique - originally developed for the 4-spacecraft Cluster mission - power spectra in k-space are estimated, enabling the determination of properties of waves and transient phenomena from those multi-scale spacecraft data. We test different spacecraft configurations probing regions mainly in the foreshock and consider conversion to the plasma rest frame, dispersion analysis as well as spectrum filtering to account for the spatial Nyquist limit in k-space spectra.
Ephemeral Ice Clouds in the Upper Atmosphere of Venus
Authors: Plane John , Murray Benjamin , Mangan Thomas , Määttänen Anni
Published: March 2024

Venus is well known for extreme heat at its surface and being shrouded in clouds composed of sulphuric acid. However, there are regions of Venus’ atmosphere around 120 km that are cold enough to harbour ice clouds, under conditions similar to the upper mesospheres of Earth and Mars where ice clouds form. In this presentation we will show, using published satellite products and numerical modelling, that the upper mesosphere of Venus can be cold enough for both H2O and CO2 to condense and form particles. Amorphous solid water particles (ASW) are likely to nucleate both heterogeneously on meteoric smoke (formed from the condensation of the metallic vapours which ablate from cosmic dust particles entering  Venus’ atmosphere) and also homogeneously, resulting in clouds of nano-scaled particles at around 120 km that will occur globally. The temperatures may become cold enough (below ~90 K) that CO2 particles nucleate on ASW particles. Taking account of the uncertainty associated with retrievals of temperature in the upper mesosphere (using the SOIR instrument on Venus Express), CO2 ice cloud formation could occur more than 30% of the time poleward of 60o. Since the main component of Venus’ tenuous atmosphere is CO2, any CO2 crystals that form will grow and sediment on a timescale of a few minutes. Mie calculations show that these Venusian mesospheric clouds (VMCs) should be observable by contemporary satellite instruments, although their short lifetime means that the probability of detection is small. We suggest that VMCs are important for the redistribution of meteoric smoke and may serve as a cold-trap, removing some water vapour from the very upper mesosphere of Venus through the growth and sedimentation of cloud particles, and possibly reducing the loss of water to space.
Evaluation of the effectiveness of the second level microzonation abacuses for the municipalities located in the Friuli Venezia Giulia (Italy) plain
Authors: Taverna Perla , Beltrame Chantal , Peressi Gabriele , Costa Giovanni , Pazzi Veronica
Published: March 2024

The local geological conditions have a significant influence on seismic waves; these differences are referred to as the "local site effect," and they must be taken in consideration when estimating the seismic effects on buildings and urban planning. In fact, local conditions could affect the seismic shaking of an area and modify the seismic wave in terms of amplitude, frequency and duration.In a very simplified approach to account for the influence of local conditions on ground shacking, according to the Eurocode 8 (EN-1998 2004), five ground types (from A to E) can be identified and used. According to this approach, an outcrop seismic bedrock is a layer characterized by Vs ≥ 800 m/s and correspond to the class A. The thickness and the shear waves velocity of the layer covering the seismic bedrock are the two factors that influence the amplification of a harmonic horizontal motion from the seismic bedrock to the surface. Thus, the equivalent/weighted average shear-wave velocity from the ground to the seismic bedrock depth H is used as a proxy for the seismic soil characteristics to design the appropriate site-dependent elastic response spectrum for structures. In a less simplified approach, the Seismic Microzonation (SM) studies aims at identifying and mapping at the urban scale the ground amplification in order to identify zones with homogeneous seismic behaviour and to assign to different areas a numerical value of expected shaking useful for the seismic design of structures. The Italian second level SM aims at quantifying the seismic amplification factor (AF) by means of abacuses for areas that can be schematised thanks to a 1D subsoil model (alluvial plain).In this work the study area is the Friuli Venezia Giulia plain municipalities and the response spectra derived applying the AF values (both from abacuses and numerical simulations) have been compared to those obtained by the Italian Building regulation that apply the Eurocode 8 approach. In general, the smoothed seismic response spectra obtained by the numerical simulations are the highest (in the 82,5% of the total sites). In other minor cases, the spectra from abacuses are higher than the numerical simulation and only in 2 sites the spectra from the Italian regulation are higher than the abacuses and the seismic response ones. Moreover, the Tc values obtained by the by Italian regulation simplified approach underestimate the amplification for short periods of time and overestimate it for longer periods. This is highlighted especially in the soil category E.
Effect of network geometry on determination of VLBI-GNSS frame orientation using a VLBI transmitter onboard Galileo satellites
Authors: Sert Hakan , Hugentobler Urs , Karatekin Ozgur , Dehant Veronique
Published: March 2024

Having a Very Long Baseline Interferometry (VLBI) transmitter (VT) onboard Galileo satellite allows us to determine the misorientation between GNSS and VLBI frames. To exploit the maximum performance, we study the operational strategies for VLBI ground segment. We simulate VLBI observations of a VT onboard a Galileo satellite to evaluate the rotation transformation between the VLBI and GNSS frames. The contribution of a VT as space tie is assessed by the evaluation of the formal precision of the orientation parameters between the VLBI and GNSS frames using different ground stations/baselines, aiming to find the optimal observation geometry for the best precision on the rotation transformation.
Insights into Asymmetric Back-Arc Basin Formation in the Mariana Trough at 17°N from Traveltime Tomography
Authors: Hilbert Helene-Sophie , Dannowski Anke , Grevemeyer Ingo , Berndt Christian , Kodaira Shuichi , Fujie Gou , Takahashi Narumi
Published: March 2024

The Mariana Trough is the youngest back-arc basin in a series of basins and arcs that developed behind the Izu-Bonin-Mariana subduction zone in the western Pacific. In addition to active seafloor spreading, the Mariana Trough also exhibits a pronounced asymmetry, with the spreading axis closer to the Mariana Arc. The formation and development of this back-arc basin and its predecessor is controlled by a complex interplay of temporal mantle heterogeneities, subduction dynamics of the Pacific Plate and large-scale tectonics since ~50 Ma. Here, we present new insights into the development of the central Mariana Trough at ~17°N from analyses of a 2-D P-wave traveltime tomography together with high-resolution bathymetric data. The refraction and wide-angle reflection data have been recorded by R/V KAIYO (JAMSTEC) on 41 ocean bottom seismometers (OBSs) along a 250 km profile in 2003. The results allow a subdivision of the Mariana Trough into different stages of back-arc basin opening and seem to imply a transition from symmetric rifting to asymmetric seafloor spreading. Fast-velocities in the lower crust in the rifting domain indicate that magma generation and crust formation was highly affected by hydrous melting from the subducting slab during this stage. This slab contribution decreases with the onset of active seafloor spreading due to a change in mantle flow and hence seems to be accompanied by a tectonic rearrangement of the eastern side of the basin.