bluuebunny/crossref_metadata_2025 huggingface dataset:
Greenland Ice Sheet evolution during the Last Interglacial with an improved surface mass balance modeling approach 
Authors: Hoang Thi Khanh Dieu , Quiquet Aurélien , Dumas Christophe , Born Andreas , Roche Didier M.
Published: March 2024

The Last Interglacial period (LIG) (130 - 116 kaBP), characterized by higher global mean temperature and sea levels compared to the present-day due to the Earth’s orbit configuration, has been well-studied as a recent example of a climate period warmer than today. There is particular interest in studying the ice sheet-climate interactions in view of our current climate change. However, the extent of the ice sheet and its contribution to the rise of sea levels during the LIG remain debatable as different approaches suggest a wide range of estimations. In order to cover such a long period, some processes are simplified in the modeling approach by using prescribed forcings, simple surface mass balance (SMB) schemes, or equilibrium simulations, which all affect the numerical estimation of ice sheet evolution. In our work, to perform transient simulations, we use an Earth system model of intermediate complexity (iLOVECLIM), which has been widely used to study various long-timescale periods. Additionally, we use a physically-based energy and mass balance model with 15 vertical snow layers BESSI (BErgen Snow Simulator) to account for the effect of insolation changes as well as snow-albedo feedback. The climate forcings of the snow model are obtained by running iLOVECLIM transiently from 135 to 115 kaBP, downscaled over the Northern Polar region. Using the SMB computed by BESSI, we then simulate the ice sheet evolution during the LIG with GRISLI - the ice sheet model in the iLOVECLIM framework. To assess the benefits of using a physically-based SMB model in the ice sheets simulation, the outputs of GRISLI-BESSI are compared to the current SMB scheme of iLOVECLIM, a simple parametrization called ITM (Insolation Temperature Melt). The Greenland ice sheet volume simulated by the two SMB models reaches the minimum value at 127.5 kaBP, around 500 years after the peak of global mean temperature. The magnitude of ice sheet retreat and its contribution to the sea level in ITM simulations are significantly higher than in BESSI due to an overestimation of the zones of ablation. The findings suggest that, compared to a parameterization, we have more confidence in the ice sheet estimation with a physically-based SMB model. Further works with fully interactive ice sheet modeling that takes into account the melt-elevation feedback can improve the simulation of the ice sheet-climate interactions of long-time scales. 
Continuous Monitoring of Stem Water Potential in Deciduous Forests: Assessing a Novel Microtensiometer for Ecosystem Hydraulics Research
Authors: Magh Ruth-Kristina , Günther Anna-Lena , Klosterhalfen Anne , Paligi Sharath , Rohde Clara , Dubbert Maren , Demir Gökben , Hildebrandt Anke
Published: March 2024

Water potential serves as the primary driver of fluxes within natural ecosystems, representing the energy of water and dictating the direction of flow. As climate change intensifies and summer droughts become more prevalent, comprehending the impact on plant hydraulics becomes imperative. The measurement of water potential in both soil and plants provides insight into the prevailing flow direction, and when coupled with soil moisture and sap flow data, facilitates the quantification of flux sizes.Traditionally, the measurement of plant water potentials has been conducted destructively and intermittently, often employing techniques such as the pressure chamber. Therefore, datapoints were usually scarce and information unsuitable to capture faster-acting hydrodynamic processes like stomatal responses to atmospheric changes or changes in plant water pools over the diurnal cycle.In this study, we evaluated the efficacy of a novel microtensiometer for continuous monitoring of stem water potential. Two Florapulse sensors were installed in a beech (Fagus sylvatica) and a hornbeam (Carpinus betulus) tree, respectively. Stem and leaf water potentials were concurrently measured using a pressure chamber over three consecutive days to validate the functionality of the sensors in these specific species. Notably, the continuously logging microtensiometer demonstrated strong agreement with hourly pressure chamber values (R2 = 0.8 and 0.72 for beech and hornbeam, respectively).Subsequently, eight microtensiometers were deployed in a natural mixed-species forest in mid-Germany, complemented by continuous measurements of sap flow, soil moisture, and soil matrix potential. This comprehensive monitoring effort spanned the entire summer of 2023. Analysis of the gathered data enabled the determination of water flow direction and fluxes throughout the monitored period, revealing minimal to negligible water stress in the ecosystem, likely attributable to the wet summer conditions in the region.This research showcases the potential of the microtensiometer for advancing our understanding of plant hydraulics in changing climates, providing a valuable tool for continuous and non-destructive monitoring of water potential dynamics in forest ecosystems.
Regional-scale landslide forecasting using physics-based slope stability models 
Authors: Abraham Minu Treesa , Piciullo Luca , Liu Zhongqiang , Robinson Haakon , Paulsen Erling Singstad , Blomberg Ann Elisabeth Albright
Published: March 2024

With the increasing frequency of high intensity rainfall events, landslides on natural slopes have become a critical concern from a disaster management perspective. Rainfall-induced landslides are caused by the reduction in the soil shear strength due to the increased pore water pressure induced by rainfall and/or rapid snowmelt. It is important to understand the mechanism of failure for employing reliable early warning and effective risk reduction strategies. Geotechnical slope stability analysis can be carried out easily on a slope scale, however, extending this at a regional scale is demanding due to the spatial variability of hydrological and geotechnical properties. Physics-based landslide susceptibility models are designed with the explicit goal of using hydrological mechanisms for the identification of possible landslide source areas, primarily computing factor of safety (FS) values on a grid.  However, given that the majority of these models operate independently, integrating them into a fully automated Landslide Early Warning Systems (LEWS) remains a significant technical challenge. This work proposes a methodology that leverages meteorological forecasts sourced from the MET Weather Application Programming Interface (API), in conjunction with topographical and soil properties, to project Factor of Safety (FS) values on an hourly basis. A case study from Norway has been used as a pilot for the demonstration of the method proposed. The forecasted FS values are dynamically visualized in real-time within the data platform of the Norwegian Geotechnical Institute, NGI Live, which can also be used as a map overlay for other infrastructure projects in the study area. The proposed method holds the promise of providing physics-based decision support for disaster risk reduction and critical infrastructure management efforts.
Enhancing coastal resilience with artificial dunes through bio-geomorphological processes
Authors: Strypsteen Glenn
Published: March 2024

Coastal regions worldwide face increasing challenges posed by the impacts of climate change, such as rising sea levels, and intensified and more frequent storm events. In response to these imminent threats, the priority for coastal resilience has gained importance, emphasizing the fusion of nature-based solutions with conventional engineering methods. Among these, coastal dunes stand out as promising protective barriers. This three-year investigation focuses on evaluating the effectiveness of an artificial dune system in mitigating local sand-related issues along the adjoining seawall, featuring the plantation of marram grass in Oosteroever, Belgium. The study delves into a comprehensive analysis of sediment accumulation, dune morphology, and vegetation development. Noteworthy findings reveal a significant increase in dune height, reaching up to 2 m in the area where marram grass was planted, surpassing the adjacent seawall in elevation. Extensive profile and drone surveys unveil a consistent growth rate of 27 m³/m, in stark contrast to substantial erosion observed in adjacent unvegetated beach areas, where erosion reached up to 30 m³/m. While one storm event resulted in dune toe erosion of 1.5 m³/m, the dune exhibited rapid recovery through natural aeolian processes. Importantly, marram grass development proved resilient, unaffected by the initial planting configuration and density, with more pronounced growth observed at the perimeter edges of the dune. This study highlights the success of the 'dune-in-front-of-a-dike' approach, providing valuable insights for the formulation of sustainable strategies in coastal resilience.
Influence of the IMF direction on Mercury's magnetosphere
Authors: Pump Kristin , Heyner Daniel , Plaschke Ferdinand , Exner Willi
Published: March 2024

Mercury, the smallest and innermost planet of our solar system, is exposed to a strong solar wind. The internal field is dipole-dominated, relatively weak, axisymmetric and significantly offset towards north. Through the interaction with the strong solar wind, this field leads to a comparatively small and dynamic magnetosphere.To first order the magnetopause completely separates the magnetosphere from the magnetosheath and thus no magnetic field may penetrate this boundary. In reality, the magnetosheath magnetic field may diffuse across the very thin boundary within a finite time.  We first investigate how the magnetosheath magnetic field changes under different IMF conditions and directions. Second, we can investigate the penetration of the magnetic field from the magnetosheath through the magnetopause inside the magnetosphere and obtain the structure of the IMF influence on the Hermean magnetosphere. 
Thermochemical models of early Earth evolution constrained by geochemical data
Authors: Jain Charitra , Sobolev Stephan , Sobolev Alexander , Vezinet Adrien
Published: March 2024

Isotopic systems and trace elements are ideal proxies to constrain the production and recycling of crust (both mafic and felsic) over time. Within the Rubidium-Strontium (Rb-Sr) system, Rb-87 decays to Sr-87 and due to the preferential partitioning of Rb into the crust (relative to Sr) during partial melting, 87Sr/86Sr ratio of the crust is higher than that of the mantle over time. Trace elements such as Niobium (Nb) and Uranium (U) do not fractionate when mantle melts to form mafic magma (oceanic crust) but they do fractionate when oceanic crust is recycled and undergoes fluid-present melting, i.e., during the production of felsic magmas (continental crust) [Hofmann et al., 1986], thereby resulting in a lower Nb/U of the felsic crust compared to the mantle. In this work, we couple the evolution of the above-mentioned geochemical proxies with the melting processes in global convection models using the code StagYY [Tackley, 2008]. Results from these geodynamic models are then compared with geochemical data obtained from olivine-hosted melt inclusions extracted from komatiites of 3.27 Ga Weltevreden formation (Barberton Greenstone Belt, South Africa).These models self-consistently generate oceanic and continental crust while considering both plutonic and volcanic magmatism [Jain et al., 2019] and incorporate a composite rheology for the upper mantle. Pressure-, temperature-, and composition-dependent water solubility maps calculated with Perple_X [Connolly, 2009] control the ingassing and outgassing of water between the mantle and surface [Jain et al., 2022]. These models show intense production and recycling of continental crust during the Hadean and the early Archean, which is in agreement with new geochemical data [Vezinet et al., in review] and previous geochemical box models [Rosas & Korenaga, 2018; Guo & Korenaga, 2020]. The thermal evolution is also consistent with cooling history of the Earth inferred from petrological observations [Herzberg et al., 2010].As the estimates of total amount of water (at the surface and in the deep interior) vary from 5-15 ocean masses (OMs) based on magma ocean solidification models to 1.2-3.3 OMs based on petrological models [Nakagawa et al., 2018], different initial values of water are also tested, which show a strong influence on the amount of felsic melts produced. Ongoing work includes incorporating the effect of water on the density and viscosity of mantle minerals and adapting the lithospheric strength with surface topography.
LEO satellite clock determination in real-time with predicted orbits introduced
Authors: Xie Wei , Su Hang , Wang Kan , Zou Min , Yang Xuhai
Published: March 2024

Low Earth Orbit (LEO) satellites have been discussed to augment the traditional GNSS-based Positioning Navigation and Timing (PNT) service in real-time, in which the high-precision real-time LEO satellite clock products are the prerequisite. As the complicated systematic effects contained in the LEO satellite clock estimates hamper high-precision mid- to long-term clock prediction, a typical and efficient method to obtain high-precision real-time LEO satellite clocks is Kalman-filter-based clock estimation with short-term prediction. The strong correlation between the LEO satellite clock and the radial orbital component, however, leads to poorer clock precision than needed. In this contribution, reduced-dynamic LEO satellite orbits are first estimated in batch least-squares adjustment with high accuracy in near real-time. The short-term predicted orbits are introduced and constrained during the Kalman-filter-based clock estimation process. The variance-covariance matrix of the introduced orbital errors is carefully considered and tested for different sets of values in the radial, along-track and cross-track directions. One week of GPS data from the Sentinel-3B onboard receiver in 2018 were used for the purpose of validation. When introducing high-accuracy predicted orbits at the first 5 min, i.e., with an accuracy of 3.33, 1.78 and 2.03 cm in the along-track, cross-track and radial direction, respectively, the precision of the estimated clocks can be improved from 0.268 ns to 0.233 ns, with an improvement of 13.06%. Moreover, the Signal-In-Space Range Error (SISRE) of the LEO satellite to the Earth can be improved from about 9.59 to 7.62 cm after introducing the predicted orbits. The results have demonstrated that the proposed method helps to improve the precision of the real-time LEO satellite clock estimates.
Dynamic Compressive Strength of Thermally Treated Barakar Sandstone
Authors: Tripathi Adarsh , Khan Mohammad Mohsin , Rai Nachiketa , Pain Anindya
Published: March 2024

Assessing the thermal influence on the dynamic mechanical properties of Barakar sandstone is crucial, notably in the examination of subsidence phenomena induced by underground coalmine fires in tandem with blast-induced loading. The Jharia region had been affected by underground coalmine fires, resulting in surface fracturing on both small and large scales. So, the objective of the study is to examine the impact of high temperature on the dynamic compressive strength of colliery sandstone subsurface samples, and its correlation with the mineralogical properties. To accomplish this objective, samples were subjected to a 24-hour heat treatment in a furnace at a controlled heating rate of 5°C/min, followed by natural cooling within the furnace. The samples were divided into five groups, each undergoing different thermal treatments at temperatures of 25°C, 200°C, 400°C, 600°C, and 800°C. The dynamic compressive strength was obtained by performing the dynamic compression tests on Split Hopkinson Pressure Bar setup. The results clearly indicate that up to a critical temperature i.e. 400°C, both quasi-static and dynamic compressive strength showing the minor strengthening effect. However, beyond this critical temperature, there is a significant decrease in strength, particularly up to 800°C. Additionally, for each temperature, the dynamic strength also exhibits an increasing trend with increase in strain rate. The study investigated the applicability of the Kimberley Theoretical Universal Scaling Law in predicting the dynamic compressive strength of thermally treated sandstone across different strain rates. Furthermore, it pinpointed the characteristic strain rate at which the dynamic compressive strength of thermally treated sandstone doubled in comparison to its quasi-static compressive strength.
Direct Numerical Simulation of Immiscible Two-phase Flow in Rough Fractures from Viscous to Capillary Fingering – Impact of Flow regime and Structure of the Aperture Field 
Authors: Neuweiler Insa , Krishna Rahul , Yang Zhibing , Yves Méheust
Published: March 2024

Immiscible fluid displacement in rough geological fractures plays a crucial role in various subsurface processes, such as enhanced oil recovery and geological carbon sequestration. In horizontal settings, this displacement is governed by capillary and viscous forces, resulting in the emergence of various displacement patterns as a less viscous fluid displaces a more viscous one (drainage). The macroscopic variables quantifying the flow process differ substantially between the two limit unstable regimes, namely capillary and viscous fingering, for very low and very large capillary numbers, respectively. While there has been extensive investigation of such phenomena in the context of porous media, studies on rough fractures are relatively scarce. In this study, we perform Direct Numerical Simulation (DNS) to analyze the process of drainage by solving the Navier–Stokes equations within the fracture pore space, employing the Volume of Fluid (VOF) method to track the evolution of the fluid-fluid interface. We consider a wide range of Capillary numbers (10-5 – 10-2) encompassing both the viscous and capillary dominated regimes, as well as three distinct viscosity ratios (0.8, 0.05 and 0.01), and address realistic synthetic fracture geometries characterized by their Hurst exponent, the ratio of the roughness amplitude to the mean aperture (denoted as the fracture closure), and the correlation scale Lc (i.e., the scale above which the two fracture walls are identical) of the investigated fracture domain. The fracture closure is varied between 0.1 and 1, and Lc between L/32 (aperture field with spatial correlations only at small scales) and L (self-affine aperture field), where L denotes the length of the domain. Starting from the invasion morphologies of the fluid-fluid interface, we examine various pore-scale and macroscopic flow observables, allowing us to systematically characterize the displacement processes of the two-phase system at the hydrodynamic scale. Additionally, flow observables, such as the residual saturation of the displaced fluid and the interfacial area, can be utilized to define the parameter functions of a continuum scale two-phase flow model towards upscaling.
Westerly jet shifts over the last glacial cycle revealed by provenance of Japan Sea dust  
Authors: Chen Lingle , Xuan Chuang , J. Crocker Anya , A. Wilson Paul
Published: March 2024

Asian deserts are major sources of dust loading to the atmosphere, second only to those of North Africa. Today, dust activation in central and eastern Asia and convective rainfall over eastern China are preconditioned by the seasonal weakening of the Siberian High-Pressure system and migration of the Westerly Jet (WJ) northwards of the Tibetan Plateau during spring. Once activated, East Asian dust is transported over long distances to the North Pacific Ocean and to Greenland. Downcore records from locations on the dust transportation pathway provide valuable information about changes in past aridity and wind systems. Recent studies suggest that the westerlies were weaker and shifted towards more poleward latitudes than today during the warm Pliocene. However, the available data are too sparse to evaluate variability on glacial-interglacial timescales and often of questionable attribution (uncertain provenance). Here we report new downcore radiogenic isotope (Nd, Sr) records of dust provenance change over the last glacial cycle (150 kyrs to present) from the Japan Sea. Our records benefit from a thorough treatment protocol to remove the imprint of contaminating marine phases (including barite) and non-dust material and show remarkably clean glacial-interglacial structure. We report a marked shift in East Asian dust sources from glacial to interglacial conditions that has important implications for our understanding of the behaviour of the Siberian High-Pressure system and the westerly jet in response to changes in atmospheric carbon dioxide concentrations and ice sheet extent on geological timescales.
Updated version of the MAX-DOAS cloud classification algorithm and its validation
Authors: Reischmann Lucas , Ziegler Steffen , Beirle Steffen , Kumar Vinod , Piters Ankie , Donner Sebastian , Wagner Thomas
Published: March 2024

Characterizing the light path through the atmosphere is a fundamental challenge in Differential Optical Absorption Spectroscopy (DOAS). Clouds strongly influence the light paths and thus the interpretation and further use of the measurements. In this context, it is important to receive information about the cloud cover in the field of view of the Multi-AXis-DOAS (MAX-DOAS) instrument. A method for extracting this information from the measured spectra themselves was introduced by Wagner et al. (2014, 2016). They developed an algorithm to determine and classify sky conditions based on the combination of CI (Colour Index) and O4 absorption obtained from MAX-DOAS spectra.In this study, the improvements of an updated version of this algorithm are presented and validated by comparison with a series of observations with camera measurements of sky conditions at several stations. In order to process the large number of observations, a tool was implemented to enable rapid categorization of the camera images.
Long-term trends in urban ozone in Europe and the USA
Authors: Nelson Beth , Drysdale Will , Lee James
Published: March 2024

High emissions of NOx and anthropogenic VOCs from urban areas are a major source of tropospheric ozone production. Tropospheric ozone is a secondary air pollutant that is harmful to human health as well as crop and ecosystem productivity, and an important greenhouse gas. It is formed from the chemical processing of NOx and VOCs in a non-linear cycle, making ozone reduction strategies challenging. Urban centres across the world are developing at different rates and emitting different combinations and concentrations of chemical species, resulting in location specific drivers of urban ozone concentrations. Alongside this, different countries and cities have implemented a wide range of location specific air quality and climate change measures to reduce air pollution and greenhouse gas emissions. The diversity of these policies over the past few decades has further led to different outcomes for secondary pollutant formation across the globe.As part of TOAR-II, long-term trends in urban ozone concentrations over the past 20 years across over 400 sites in Europe and the USA will be explored. This study utilises the TOAR database, accessed via the TOAR Data Portal, which collects hourly data of long-term surface air quality measurements from over 10,000 stations globally. Using ground-based data from air quality monitoring networks, seasonal trends in ozone and NO2 concentrations are explored alongside trends in peak ozone and MDA8.  Global 5-year trends in ozone and NO2 will also be examined, extending the analysis to include urban centres in China and South America. The period between 2018-2022 will be investigated, allowing us to take a closer look into the impact of COVID-19 in cities across the world. This study aims to assess trends in urban ozone and NO2 across Europe and the USA, and to explore how lockdowns and restrictions during the COVID-19 pandemic might reveal insights into a lower NOx emission future.
Hotspots of Multi-hazard Risk to Human Health in a Changing Climate
Authors: Stalhandske Zélie , Chambers Jonathan , Kropf Chahan , de Ruiter Marleen C. , Bresch David N.
Published: March 2024

The health effects of climate change, from intensified heatwaves to increased environmental suitability for infectious diseases, have become increasingly evident in recent years. In this study, we investigate the intersection of multiple climate-related health hazards from 2003 to 2022 using indices from the Lancet Countdown on Health and Climate Change, including heatwaves, drought, malaria, and wildfire smoke exposure. Through a global analysis at a 0.25-degree resolution, we identify regions where these hazards have overlapped, highlighting hotspots of simultaneous exposure. We then perform detailed case studies in countries most affected by these hazards, where we explore the interactions between seasonal climate variations, demographic shifts, and the exposure to health hazards. The findings of this study can help guide health system adaptations and inform policy by revealing where, when, and whom these hazard combinations affect. Finally, while the health effects of some of these combinations have been studied, the compounding effects are generally unknown. Mapping their co-occurrence can help in designing relevant epidemiological studies to better understand these consequences.
Plagioclase preferred orientation provides insights into magma flow dynamics of a basaltic dyke from the Budj Bim Volcanic Complex, Australia
Authors: Hrintchuk Jade A. , Kavanagh Janine L. , Mariani Elisabetta
Published: March 2024

To understand the style, longevity and hazards of volcanic fissure eruptions, we need to understand the magma flow dynamics governing their feeder dykes. Microstructural analysis through optical microscopy and electron backscatter diffraction (EBSD) can be used to observe crystal alignment, shape and size from dyke samples to investigate magmatic fluid flow and deformation processes during the ascent of magma. Plagioclase is a mineral ubiquitously found in volcanic rocks that forms throughout magma crystallisation at a wide range of temperatures (~1300-400°C), and is therefore a mineral commonly used to investigate magma flow dynamics in dykes and sills. In particular, microlites of plagioclase (
Uncovering the Influence of Dust-Induced Aerosol Particles on Ecosystem Carbon Uptake
Authors: Budakoti Sachin , Khadke Leena , Verma Akash , Mukherjee Sandipan , Ghosh Subimal
Published: March 2024

Understanding the intricate relationship between dust-induced aerosols and ecosystem carbon uptake is essential to resolving the complexities of global carbon cycling. Aerosols play a crucial role in altering surface solar radiation, thereby influencing plant productivity. Despite their recognized role in modulating weather patterns, the precise mechanisms underlying aerosol-induced alterations in gross primary productivity (GPP) remain unclear. Previous studies suggest that aerosols may exert positive or negative impacts on ecosystem carbon uptake, subject to aerosol loading and cloud conditions. The present study uses Moderate Resolution Imaging Spectroradiometer (MODIS) AOD and GPP along with the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA5) reanalysis datasets to investigate the effects of aerosol-induced radiation perturbation and eco-hydro-meteorological feedback on GPP in Himalayan ecosystems. We observe that the long-range transportation of dust-induced aerosol particles from the Middle East over Northern India is influencing air quality and weather patterns. It creates a thermal gradient that keeps surface temperatures lower than the top of the atmosphere. Consequently, the reduction in surface temperature and vapor pressure deficits contribute to variations in carbon uptake. We plan to examine multiple events where high aerosol loading contributes to extreme weather conditions like dust storms. Further, we will validate our results with flux tower measurements. Our findings show the significance of the interactions among aerosol pollution, climate change, and the global carbon cycle, which have unavoidable implications on weather patterns and direct impacts on human health and the tourism industry.Keywords: Aerosol optical depth, Carbon Uptake, Dust, Himalayan ecosystems
Quantifying changes in temperature sensitivity of spring phenology over recent decades
Authors: Zohner Constantin
Published: March 2024

Understanding the factors driving leaf-out times in temperate and boreal trees is increasingly vital in the context of rapid climate change, as it is crucial for predicting ecosystem dynamics. This study investigates if and how the sensitivity of spring phenology to temperature (St) has evolved in recent decades, especially given the ongoing debates about the extent and direction of future phenological shifts. Leaf-out times are influenced by a mix of spring warming, winter chilling, and day length, with their significance varying across different species. However, climate change could reduce St due to warmer climates and earlier spring onset, potentially enhancing winter chilling and day length constraints. To evaluate the relative importance of these factors, we conducted a comprehensive analysis using both long-term ground observations and satellite-derived phenology data, covering a span of six decades. Our approach included simulations to better understand the mechanisms behind variations in species-level Ts. This research aims to determine whether the phenological responsiveness of trees to climate change is decreasing, taking into account both environmental and physiological factors. Our findings challenge the prevailing belief of a consistent decline in St sensitivity, underscoring the need for a more nuanced understanding of the drivers behind leaf-out phenology in a changing climate. This study adds to the ongoing discourse on how global warming shapes natural phenomena and is pivotal for forecasting how ecosystems will respond to environmental changes.
Efficient Extraction of Tree Parameters from 3D Point Clouds
Authors: Groiss Bernhard , Handl Markus
Published: March 2024

In the realm of environmental monitoring and urban planning, the accurate assessment of tree parameters from 3D point clouds is essential for effective resource management and decision-making. This paper introduces a versatile and user-friendly approach designed to streamline the extraction of key tree parameters from 3D point clouds.The related software employs advanced point cloud processing algorithms to identify and analyze individual trees within a point cloud dataset, acquired through terrestrial laser scanners (TLS), facilitating the extraction of crucial parameters such as tree height, crown diameter, and trunk diameter at breast height (DBH). Leveraging state-of-the-art computer vision techniques, this approach ensures high precision and efficiency in tree parameter extraction, even in complex and densely vegetated environments.Key features include an intuitive graphical user interface, allowing users to interactively visualize and validate the extracted tree parameters. The ability to adjust the various tree extraction and segmentation settings at any time gives the user complete freedom to modify their analysis to their needs.The results showcase the software's ability to accurately and efficiently extract tree parameters, making it a valuable tool for researchers, urban planners, and environmental professionals engaged in forestry management, green infrastructure planning, and ecological monitoring.A reliable database and a procedure suitable for everyday use are enormously important to ensure highly accurate monitoring and to cope with the ever faster changing conditions and their effects on vegetation. Therefore an additional approach to use a terrestrial laser scanner in kinematic mode is presented, which allows the generation of a comprehensive point cloud in a short time.Overall, the software LIS TreeAnalyzer, a plugin to RIEGL’s RiSCAN PRO, contributes to the advancement of 3D point cloud analysis by providing a robust solution for the extraction of tree parameters, ultimately supporting sustainable urban development and informed decision-making in the field of environmental science and resource management.
The NEPOS Project: Near-Surface Seismic Exploration of Planetary Bodies with Adaptive Networks
Authors: Keil Sabrina , Igel Heiner , Bernauer Felix , Shutin Dmitriy , Shin Ban-Sok , Nierula Kai , Reiss Philipp , Sesko Rok , Lindner Fabian
Published: March 2024

Ground motion observations on planetary objects are a prerequisite for a detailed understanding of their interior structure and evolution. The imaging of the near surface structure - in particular on the Moon - has strong practical implications. First, the race is on to detect ice-bearing rocks near the surface from which water could be extracted and used as a resource for crewed missions. Second, due to the substantial bombardment of the lunar surface with meteorites and the lack of an atmosphere, observatories or habitats may have to be built underground. It has been proposed that cavities from ancient lava flows below the lunar surface could be used to place infrastructure. Current mission plans for geophysical exploration focus on static seismic sensors/arrays that would be restricted to the area they can explore.       With the NEPOS project we want to go beyond these restrictions and develop concepts for mobile seismic arrays that work in an autonomous way using robotic technology. The scientific challenges include the understanding of wavefield effects of icy rocks and caves in a strongly scattering environment, the provision of optimal source-receiver configurations to detect them, as well as an integrated data-processing workflow from observation to subsurface image including the quantification of uncertainties.    In order to solve these challenges, we first developed a Digital Twin for wave propagation in the strongly heterogeneous lunar crust to generate synthetic seismic data using the spectral element code SALVUS. We compared the synthetic seismograms to data from the Apollo 17 Lunar Seismic Profiling Experiment (LPSE) and find that their main characteristics coincide. We further generated synthetic seismograms for a variety of network configurations and subsurface heterogeneities, which will be used to test appropriate imaging methods for the lunar subsurface structure. Due to the presence of strongly scattering media ambient noise tomography seems to be a promising method, as was already shown in previous studies. We apply seismic interferometry to LPSE data, as well as to our synthetic seismograms, to reconstruct Green’s functions, which give us information on the subsurface properties.
Comprehensive assessment of sea-ice thickness datasets: The ESA SIN’XS project
Authors: Ludwig Valentin , Belot Carole , Da Silva Elodie , Fleury Sara , Haas Christian , Hendricks Stefan , Munesa Eric , Pastor Javier , Paul Stephan , Tsamados Michel , Bouffard Jérôme , Di Bella Alessandro , Scagliola Michele
Published: March 2024

Sea-ice thickness is a crucial parameter for a variety of scientific disciplines, including climate science, oceanography, and ecology. It plays a vital role in regulating exchanges of heat, moisture and momentum between the polar oceans and the atmosphere, influencing ocean currents, and affecting local cloud cover and precipitation.The ESA-funded project SIN’XS, led by NOVELTIS, AWI, LEGOS, and UCL, aims to comprehensively assess available sea-ice thickness and snow thickness products and their uncertainties. We are building up a database of large-scale datasets (satellite-based and models) as well as reference datasets (in-situ, airborne, moorings, etc.) to better understand the variability and change in observed ice thickness in both hemispheres. A web portal enables users to interactively explore and analyse data. In the talk, we will introduce the project and database and present the first results. We will also encourage potential collaborators to contribute to the project by submitting data to our website. We look forward to collaborating with the scientific community to better understand the complexities of sea-ice thickness and its impact on our planet. The ultimate goal of SIN’XS is to provide a reconciled and comprehensive sea-ice thickness estimate.
Investigating the coherency and expansion of ICMEs using multi-spacecraft observations
Authors: Davies Emma , Möstl Christian , Weiler Eva , Forsyth Robert
Published: March 2024

Studies of ICMEs observed by multi-spacecraft over varying longitudinal and radial separations provide valuable insight into the general properties, expansion, and possible interaction with other features of the solar wind environment as the ICME propagates. Previous studies have suggested that ICMEs are not coherent structures, but may display locally apparent coherence due to similar initial conditions and quasi homogeneity of the solar wind background through which they propagate.In this study, we use a tool to match distinct features observed in the magnetic field profiles measured at each spacecraft as a proxy for coherence, and investigate the types of ICME and scales over which this is possible using those listed in the HELIO4CAST lineup catalogue v2.0 (https://helioforecast.space/lineups). In addition, we use the timing and positions of these matched features to calculate the mean propagation velocities of these features between the spacecraft. We present example CME events comparing the calculated mean propagation velocity profiles to those measured in situ where plasma data is available, and investigate the relationship between local and global expansion.
Receiver function modelling of the lithosphere beneath the Sinai Subplate, west of the Dead Sea fault system
Authors: Mukherjee Pousali , Wetzler Nadav , Kurzon Ittai , Tal Yuval
Published: March 2024

The Sinai subplate in the eastern Mediterranean region separates the African and Arabian plates, and is demarcated on the east by the Dead Sea fault (DSF). The shallow and deep crustal Vs and Vp/Vs variations of the eastern Sinai subplate beneath Israel, as well as mantle properties, are not well constrained. With the recent development of the regional seismic network, we present new geophysical observations beneath the Sinai subplate. We focus on the crustal and mantle structure using receiver functions (RF) to image the lithosphere beneath the eastern Sinai subplate, including backazimuth variations. Around 250 teleseismic earthquakes greater than magnitude 6.0 from 2018-2023 are used for our analysis. The obtained receiver functions reveal negative conversions from basin structure, and positive phases from the sediment layer and Moho discontinuity, with backazimuth variations. RF computation is followed by inversion for investigating the shear velocity and Vp/Vs variations across depth, from shallow depths in the crust, extending to deep crust and mantle. An extensive Moho variation under the area is observed by integrating findings from this study and prior investigations. RF and inversion profiles reveal additional insights into seismic boundaries in the crust and mantle beneath the region. The lithospheric architecture beneath the eastern Sinai subplate highlights variations in crust and mantle properties beneath the region, along profiles stretching from north-west to south-east direction beneath the Sinai subplate, and along the strike of the DSF. This work enhances our understanding of the underlying lithosphere beneath the region and offers valuable insights into the evolution of the Sinai subplate and Dead Sea basin zone.
From slow to fast earthquakes: laboratory insights on acoustic and mechanical fault slip behavior
Authors: Pignalberi Federico , Giorgetti Carolina , Romanet Pierre , Tinti Elisa , Marone Chris , Scuderi Marco
Published: March 2024

A critical aspect of studying earthquake mechanisms involves understanding why a single fault can exhibit various slip behaviors. Fault heterogeneity leads to different slip behaviors in different fault portions: some slip seismically, generating catastrophic earthquakes, while others slip a-seismically in a stable and silent manner. Additionally, some fault portions exhibit slow, intermittent slip that can persist for months. Unraveling the physical mechanism at the base of these different fault slip behaviors is crucial for understanding how fault portions that slip slowly interact with portions capable of producing earthquakes.In a laboratory setting, we can replicate the entire spectrum of fault slip behaviors by changing the loading stiffness of our experimental apparatus. Tuning the loading stiffness, we are able to match the critical rheological stiffness of the fault (kc) and investigate conditions around the critical point where k/kc = 1. Moreover, monitoring acoustic emissions (AEs) during laboratory earthquakes allows us to capture the rupture processes throughout the seismic cycle.To constrain the nucleation mechanisms and rupture processes of different slip behaviors, we conducted friction experiments using quartz powder (MinUSil, average grain size 10 µm) to simulate fault gouge. The experiments were carried out in a double direct shear configuration, using an array of calibrated piezoelectric sensors for continuous, high acquisition rate (6 MHz) AE recording. The experiments were conducted at a constant displacement rate of 10 µm/s. During each experiment we maintained a constant normal stress and changed three acrylic blocks of different areas to change the apparatus stiffness (k). This technique allows us to reproduce both fast (i.e., when the apparatus stiffness is lower than a critical stiffness, k
Understanding the South-West Indian Ocean Temperature Bias: Forcing Ocean-Only Models with Coupled Model Atmospheric Output to Identify Drivers of Ocean Biases
Authors: Ellis Hannah
Published: March 2024

The Seychelles-Chagos Thermocline Ridge (SCTR) is a region of open-ocean upwelling in the south-west tropical Indian Ocean. It plays a prominent role in regional ocean dynamics, local and remote climate variability, and can influence the onset of the Indian summer monsoon and the formation of tropical cyclones in the region. This highlights the importance for global coupled models to be able to accurately simulate the dynamics of the SCTR. The upwelling in the SCTR is primarily wind-driven, namely by the local negative wind stress curl between the south-easterly trade winds and the equatorial westerlies. Therefore, any model biases present in the local winds will have a subsequent effect on the strength of the upwelling.
The Met Office global coupled model exhibits a significant subsurface warm bias in the SCTR region.  Its location makes it part of the western pole of the Indian Ocean dipole; therefore, its existence affects the representation of Indian Ocean climate modes and their associated teleconnections. The bias shows a strong seasonal cycle, peaking in boreal winter and subsiding from spring. This warm bias is not seen in the ocean-only model when forced by reanalysis data. We hypothesise that the temperature bias is due to a lack of ocean upwelling caused by biases in the surface winds in the coupled model.
To test this hypothesis, an ocean-only model was forced by the surface winds from the coupled model with all other atmospheric forcings taken from reanalysis. We also test the impact of forcing the ocean model with winds from an atmosphere only simulation. We will examine whether the coupled and atmosphere-only wind biases are effective in recreating the temperature bias in the ocean-only model and investigate the potential role of coupled feedbacks.
Comparison of different interpolation techniques for sub-basins located in Madrid.
Authors: Cuevas Blanca , Pascual Elena , Bernal Carlota , Zubelzu Sergio
Published: March 2024

Soil hydrophysical properties can be very spatially and temporally heterogeneous even in small areas. Due to this spatial and temporal variability, it is impossible to obtain real data for each point of interest. Therefore, the possibility to obtain the optimal estimated value, at any desired point, is decisive. The aim is to evaluate different methods to minimise the error made in this measurement.Two basins were selected in the Autonomous Community of Madrid (Spain), where hydraulic conductivity data were taken at different points. All sampling point in both basins were georeferenced. For each basing different interpolation methods were tested. The methods used are Spline, Inverse Distance Weighted Interpolation (IDW), Kriging, and Thiessen Polygons. With the help of the Matlab program, the values for each method were obtained. Finally, the error is used for the analysis.Differences among the obtained data by each method are expected to be found. In addition to the differences between the number of samples and the error, and the location in the basin of the samples.In conclusion, it is hoped to find the most appropriate method for obtaining a value as close to reality as possible. Furthermore, it is expected to be able to use this methodology in other situations.Acknowledgements: This research Project has been funded by the Comunidad de Madrid through the call Research Grants for Young Investigators from Universidad Politécnica de Madrid
Periglacial processes and landforms in the European Alps: From the Last Glacial Maximum via Leonardo da Vinci to the present
Authors: Kellerer-Pirklbauer Andreas , Gärtner-Roer Isabelle , Bodin Xavier , Paro Luca
Published: March 2024

Periglacial landforms are widespread features in the European Alps, which cover an area of 190,900 km². The mountain range is arcuated in the western part, extend over a length of 1200 km, are up to 280 km wide, and reach their highest elevation at Mont Blanc (4807.8 m a.s.l.) at the French/Italian border. About 19% of the Alps exceed 2000 m and some 52% of the area consists of carbonate rocks at the surface, which is relevant for karstification processes. During the Last Glacial Maximum some 20 ka ago, 55% of the Alps were covered by glaciers whereas the remaining area was impacted by moderate to severe periglacial conditions causing the formation of widespread periglacial landforms still visible today, particularly at the Alpine margin. During the following Late Glacial period terminating with the Younger Dryas period about 11.7 ka ago, previously glaciated areas were reshaped by periglacial processes forming for instance complex rock glacier systems and solifluction landforms which characterize many high-elevated regions in the Alps until today. Nowadays, active periglacial processes are restricted to elevations above 2000 m in the marginal areas and above 2400 m at the central parts of the Alps. Around 11% of the European Alps are in this active periglacial belt, constrained by the potential treeline as the lower limit and the currently glaciated areas (1% of the Alps) as the upper limit. The widespread existence of relict and active periglacial landforms in the Alps inspired research by many scholars and scientists since centuries. Even Leonardo da Vinci made some periglacial-related observations in the late 15th century. Despite this long traditions and comprehensive experiences in periglacial landform research, future periglacial research is still needed and will help to better understand the impact of ongoing climate change on the periglacial reshaping of this remarkable mountain chain. In this contribution we will present a summary of a recently published book chapter dedicated to the European Alps (Kellerer-Pirklbauer et al. 2022), which is part of a book dealing with the periglacial landscapes of Europe (Oliva et al. 2022).References:Kellerer-Pirklbauer A, Gärtner-Roer I, Bodin X, Paro L (2022) European Alps. In: Oliva M, Nyvlt D, Fernández-Fernández JM (eds), Periglacial landscapes of Europe. Springer, Cham. 147-224. https://doi.org/10.1007/978-3-031-14895-8_9Oliva M, Nyvlt D, Fernández-Fernández JM (eds) (2022) Periglacial landscapes of Europe. Springer, Cham. 523 pp. https://doi.org/10.1007/978-3-031-14895-8