bluuebunny/crossref_metadata_2025 huggingface dataset:
Heitt Mjolnir: an internally heated triaxial rock deformation apparatus for operando experiments at up to 573 K at Synchrotron imaging beamlines
Authors: Freitas Damien , Butler Ian , Elphick Stephen , Gilgannon James , Rizzo Roberto , Pluemper Oliver , Wheeler John , Schlepuetz Christian , Marone Federica , Fusseis Florian
Published: February 2023

The 3rd and 4th generation of synchrotron light sources with their high brilliance, fluxes and beam energies allow the development of innovative X-ray translucent rock deformation apparatus that maximise these capabilities. Following on from the development of the Mjolnir triaxial deformation rig (Butler et al., 2020), we present an upscaled design: Heitt Mjolnir, covering a wider temperature range and larger sample volume while operating at similar pressure, enabling a wide range of time-resolved investigations. This device is designed to characterise coupled hydraulic, chemical and mechanical processes, occurring at various temperatures, from the µm to the centimetre scale in cylindrical samples of 10 mm diameter and 20 mm length. Heitt Mjolnir can simultaneously reach confining pressures of ≤30 MPa (hydraulic), 500 MPa of axial stress while the sample’s pore fluid pressure is controlled in a dedicated fluid channel and can reach 30 MPa. This apparatus has an internal heating system and is able to reach temperatures of 573 K in the sample with a minimal vertical thermal gradient of <0.5 K/mm. This portable and modular device has been successfully deployed in operando studies at TOMCAT (SLS) and I12 JEEP (DLS) beamlines for 4D X-ray microtomography with scan intervals of a few minutes. Heitt Mjolnir allows the 4D characterisation of low-grade metamorphism, fluid-rock interaction and deformation processes. It enables spatially and temporally resolved fluid-rock interaction studies at a wide range of conditions and, by covering most geological reservoirs, will be particularly valuable for geothermal, carbonation or subsurface gas storage research.
Synthetic satellite images of Mars dust storms based on MarsWRF dust cycle simulations and the radiative transfer model DISORT
Authors: Alkaabi Fatima , Gebhardt Claus
Published: February 2023

This presentation adds to Mars dust storm research based on numerical models and spacecraft images. The focus is the conversion of MarsWRF model data into synthetic satellite images of Mars dust storms. MarsWRF is a Mars version of the terrestrial numerical weather and climate model WRF (Weather Research and Forecasting Model) and part of the PlanetWRF models for planetary atmospheres research. Dust storms are obtained by running the MarsWRF model with the interactive-dust-lifting-technique [1]. Synthetic satellite imagery is generated from MarsWRF model data by using the radiative transfer model DISORT, which provides the top-of-the-atmosphere reflectance data. The results are synthetic satellite images, mostly for visible light wavelength. We compare synthetic satellite images of dust storm events at different times of the Martian Year.[1] Gebhardt, C., Abuelgasim, A., Fonseca, R. M., Martín-Torres, J., & Zorzano, M.-P. (2020). Fully interactive and refined resolution simulations of the Martian dust cycle by the MarsWRF model. Journal of Geophysical Research: Planets, 125, e2019JE006253. https://doi.org/10.1029/2019JE006253
The potential to reconstruct 20th century soil carbon erosion in rangelands from small reservoir sediments
Authors: Li Lu , Krenz Juliane , Kuhn Nikolaus J
Published: February 2023

Land degradation affects the productivity of the land, but is also associated with a flux of greenhouse gases (GHGs) from soil and vegetation into the atmosphere. The large area of rangelands (35 million km2, cover about 40% of earth’s surface) can contribute significantly to changes of atmospheric CO2 concentrations following even a minor alteration of the rangeland soil C pool (Wang et al. 2002). Degradation of South African rangelands has been a concern for more than 100 years (Rowntree, 2013). The Karoo drylands, covering 30% of the land surface of South Africa, have experienced particular intense soil erosion and thus loss of topsoil C. To sustain the large number of animals, many small farm dams have been constructed mainly in the first half of the twentieth century. As a consequence of the soil erosion, they are now often silted-up and have breached (Boardman, 2014). The sediment deposited behind such small dams offers the possibility to reconstruct the loss soil C for the time peirod between construction and breaching of dams. Five dams were chosen to explore the possibility to use their sediment as an environmental archive for 20th century rangeland soil Carbon loss. The specific aims of our study are to 1) find out whether distinct C profiles can be discerned in dam sediments; 2) identify whether these changes potentially reflect erosion and soil C loss in the dam catchments; and 3) to discuss whether the dam sediments can serve as an environmental archive to reconstruct soil-atmosphere interaction during recent decades. The initial survey of the dams involved the sampling of individual sediment strata and the analysis of their organic and nitrogen content, as well as the 137Cs activity of selected samples to gain an insight into the time of deposition. Two dams showed a profile that indicates a loss of soil C during the first decreased after their construction, while the other dams showed no clear signal or even an increase of sediment C in the younger sediment. One dam showed no 137Cs activity, indicating that it was filled with sediment very quickly after construction. These results illustrate that soil degradation and associated loss of soil C stocks can potentially be reconstructed based on the small dam sediments. However, the source of the sediment C has to be tested, as well as the individual land use and erosion history of each dam catchment. 
Quantifying the effect of CME erosion on geo-effectiveness using EUHFORIA
Authors: Maharana Anwesha , Vanwalleghem Yarrik , Baratashvili Tinatin , Poedts Stefaan
Published: February 2023

Coronal mass ejections (CMEs) interact with large-scale solar wind structures and other CMEs during their propagation in the heliosphere and undergo erosion, deflection, and deformation. In this work, we aim to quantify the erosion of the CMEs in different solar wind backgrounds using 3D MHD simulations. The EUropean Heliosphere FORecasting Information Asset (EUHFORIA; Pomoell and Poedts, 2018) is employed to create a relaxed solar wind background and evolve a CME on top of it between 0.1 au and 2 au. The LFF spheromak model is used to model the CME. Initially, we assume a simple dipolar background wind mimicking a solar minimum condition. CMEs with different geometric and magnetic field parameters (geometrical size, chirality, polarity, and magnetic flux) are evolved, and the evolution of the CME mass and the magnetic flux contained in the magnetic cloud is tracked to quantify mass and flux erosion. We also quantify the deformation of the CME during its evolution by parameterizing the separatrix surface of the magnetic cloud. The same experiment is repeated in the presence of a stream interaction region (SIR) interacting with the CME. We characterise the deformation of the different sides of the CME (with and without the interaction with SIR). In addition, we explore the adaptive mesh refinement and stretched grid features of the upgraded EUHFORIA heliospheric wind model, i.e., the newly developed ICARUS model (Verbeke et al., 2022) to resolve the CME shock and magnetic cloud and find the conditions to improve the modelling of the sheath region. Although the analysis of CME erosion has been carried out in 2.5D (axisymmetric) in previous works (Hosteaux et al., 2021), we explore the differences in 3D, which is required to fully quantify the erosion and deformation, and investigate their effect on the CME arrival time and geo-effectiveness at Earth.
Wet deposition of heavy metals, reactive nitrogen species and dissolved organic carbonat a residential site in Delhi region, India
Authors: sunaina sunaina
Published: February 2023

The deposition of heavy metals on water bodies and soil has adverse consequences onhuman health. The elevated Coal-based energy production and increased industrial emissionshave also prompted us to study about heavy metals reactive nitrogen species in theatmosphere. In the present work, the samples of rain water were collected from a residentialsite in south-west Delhi. The samples were analyzed for selected heavy metals by using ICP-OES. The heavy metals analysis involved voltammetry method using 797 VA Computrace(Metrohm, Switzerland) instrument. The analysis of Total Nitrogen (TN) and dissolvedorganic carbon (DOC) was carried out by using chemiluminescence based TN/TOC analyzer(Shimadzu model TOC-LCPH E200 ROHS). The mean values of Cu, Mn, Zn, Al, As and Hgwere calculated as 34.5 mg/l, 19.5 mg/l, 52.7 mg/l, 392.3 mg/l, 9.8 mg/l and 1.6 mg/lrespectively. The mean values for TN and DOC were 12.7mg/l and 2.8 mg/l respectively. Thedetailed results will be discussed in the EGU General Assembly Meeting.Keywords: Total Nitrogen, wet deposition, ICP-OES, voltammetry, agricultural area.
Mathematical modeling of dispersed phase behavior of water-in-oil emulsions in electrostatic crude oil desalters
Authors: Kooti Ghazal , Dabir Bahram , Taherdangkoo Reza , Butscher Christoph
Published: February 2023

The produced crude oil from reservoirs usually contains a considerable amount of water which is submitted to large shear rates through production process, and due to the existence of natural surface-active agents in crude oils, stable water-in-oil (W/O) emulsions are formed. Effectively purifying the emulsified crude oil through the electrostatic desalting process plays an important role in reducing its water and water-soluble salts contents, which otherwise exacerbate oil deterioration, equipment corrosion, and catalysts deactivation in subsequent units. The electrostatic desalting process has proved to be an efficient means of separation using electrodes subjected to a high voltage to enhance the coalescence of water droplets. In this study, a mathematical model was developed to simulate the W/O dispersed flow to study the evolution of droplet size distributions in crude oil desalters. The population balance approach was employed to describe the behavior of W/O emulsions in the continuous phase assuming that the process is controlled by two simultaneous physical phenomena; breakage and coalescence of droplets. Experimental results on the W/O system were utilized to validate the mathematical model and the employed numerical technique. The agreement between the developed model and experimental droplet volume size distributions was shown to be satisfactory, confirming the further applicability of the model. The present study can be helpful for optimizing crude oil desalting operating conditions, enhancing efficiency, and decreasing energy and chemical consumption.
Improving Combined EOP Series by Jointly Determining Them with the Terrestrial Reference Frame
Authors: Gross Richard , Abbondanza Claudio , Chin Mike , Heflin Mike , Parker Jay
Published: February 2023

Earth orientation parameters (EOPs) are currently determined from measurements taken by the space-geodetic techniques of SLR, VLBI, GNSS, and DORIS. But each technique has its own unique strengths and weaknesses in this regard. Not only is each technique sensitive to a different subset and/or linear combination of the EOPs, but the averaging time for their determination is different, as is the interval between observations, the precision with which they can be determined, and the duration of the resulting EOP series. By combining the individual series determined by each technique, a series of the Earth's orientation can be obtained that is based upon independent measurements and that spans the greatest possible time interval. Such a combined Earth orientation series is useful for a number of purposes, including a variety of scientific studies and as an a priori series for use in data reduction procedures. However, care must be taken in generating such a combined series in order to account for differences in the underlying reference frames within which each individual series is determined (which can lead to differences in the bias and rate of the Earth orientation series). Traditionally, differences in the underlying reference frames are accounted for by applying a correction to the bias and rate of each individual series being combined with the goal of placing the series within a common reference frame. But there is an uncertainty associated with estimating the bias and rate correction that needs to be applied to each series. In fact, this uncertainty is a major (if not the major) source of error in combined EOP series. However, this source of error can be mitigated by jointly combining the EOP series with the terrestrial reference frame. Recent ITRF and JTRF solutions such as ITRF2020 and JTRF2020 have included EOP series in their determination. In this presentation, the ITRF2020 and JTRF2020 combined polar motion series will be compared to the more traditionally determined IERS Bulletin A and JPL KEOF (Kalman Earth Orientation Filter) combined polar motion series in order to study the improvement attained by jointly determining the combined EOP series with the terrestrial reference frame.
Resistivity structure of Denizli Çürüksu & Acıgöl Graben connection: Preliminary results from 3D inversion of magnetotelluric data
Authors: Karcioglu Gokhan , Turkoglu Ersan , Avsar Umit
Published: February 2023

The western part of the Anatolian peninsula is defined with an N-S extensional regime and resulting graben systems, referred as the Aegean Extensional Province (AEP). The transition of this extensional regime in the west to E-W compressional regime in the east is bounded by the Isparta Angle, which is a reverse v-shaped major structure developed due to nappe emplacements and related clockwise and counter-clockwise rotations.

The study area is located at the eastern end of the Curuksu Graben and covers the western part of the Acigol Graben. Curuksu Graben is part of the Denizli Horst-Graben system and located between the junction point of three major grabens of the AEP in the west and Acigol Graben in the east. The development of the Graben systems in the AEP, including Curuksu and Acigol grabens, is resulted from two extensional periods interrupted by a compressional phase creating a disconformity between deformed ancient and undeformed neotectonic graben fills in the region. Denizli Horst-Graben System consists of incipient grabens and the modern graben (Curuksu Graben) which is developed with the introduction of the neotectonic regime with the latest Pliocene. This episodic development caused an inward development of normal faults. The compressional regime created many strike-slip and reverse faults in the region while many of the currently active normal faults with strike-slip components are resulted from the present day NNE-SSW extensional phase, including seismically active margin-bounding major faults with seismic hazard potential.

In this study, we have reassessed the data from 300 Magnetotelluric stations which were previously collected by a private contractor for geothermal research purposes. We have investigated the main properties of the data with Phase Tensor analysis and inverted it using ModEM software to reveal 3D subsurface conductivity structure of the area. Our analysis shows that the Phase Tensor ellipses for the highest frequencies indicate rather 1D behavior in compliance with the undeformed, nearly horizontal bedding of the neotectonic graben fills. The strike directions obtained through induction vectors and Phase Tensor ellipses reflects the dominant effect of the major faults and conductive basin fills. The recovered model from the 3D inversion results show the depth of the basin fills and conductivity anomalies due to normal faults controlling the basin development.
Artifact-Free Measurements of Isotopic Composition for Atmospheric and Planetary Gas Analysis
Authors: Bailey D. Michelle , Srivastava Abneesh , Hodges Joseph , Fleisher Adam
Published: February 2023

The isotopic composition of gaseous species can provide critical information regarding the age and chemical or physical origin of sample material. However, the challenge of maintaining isotope abundance scales – generated by comparing sample measurements to those of a reference material having finite quantity and stability – may limit inter-laboratory agreement and consequently the uncertainty evaluation of new measurement methods. Here we will present progress towards realization of artifact-free isotope scales and rapid measurements of isotopic composition enabled by absolute SI-traceable measurement schemes.We will discuss how cavity ring-down spectroscopy techniques, capable of highly precise and accurate measurements of transition-resolved peak areas, can be leveraged in combination with quantum chemical calculations of transition moments to enable measurement of molecular isotopologue ratios [1]. We will also introduce direct frequency comb spectroscopy methods for rapid and precise measurement of isotopic abundance [2]. This discussion will include demonstrations in the near- and mid- infrared spectral regions employing cross-dispersed spectrometers. Implications for carbon, nitrogen, and oxygen isotopic analysis will be presented.Applications of these SI-traceable measurement approaches include accurate source apportionment and greenhouse gas inventories, radiocarbon dating, isotope forensics, with the potential for high-impact contributions to emerging advances in exoplanetary studies and astrophysics.[1] A. J. Fleisher, H. Yi, A. Srivastava, et al., Nat. Phys. 2021, 17, 889-893[2] D. M. Bailey, G. Zhao, and A. J. Fleisher, Anal. Chem. 2020, 92 (20), 13759–137
Synthetic hydrological data consistent with climate reanalysis to enable long-term hydrological modelling
Authors: Gerber Loïc , Mariéthoz Grégoire
Published: February 2023

High-density gauging station networks and complete hydrological time-series are needed to adequately model and manage water resources and assess the effects of climate change on hydrological processes. In data scarce regions however, remote sensing data has proven to be a viable alternative, but before the year 2000 satellite records often contain gaps or are not available at all.We propose to create synthetic images of precipitation, temperature, evapotranspiration, and terrestrial water storage products to complete and extend past data availability to pre-satellite periods. Ideally, the synthetic images should be indistinguishable from real satellite acquisitions. The approach used is based on the relation between meteorological predictors and available satellite images, and the hypothesis that, under similar meteorological conditions, patterns of a particular process may be repeated over the years. Using ERA5 reanalysis data as meteorological predictor, a K-Nearest Neighbor algorithm associated with a process-specific similarity metric is applied to create synthetic images of the different satellite products.The approach is tested on the Volta River Basin in West Africa, where water resources for millions of people are critically stressed by the effects of climate change. For calibration and validation, the synthetic images are fed to a spatially-distributed hydrological model (the mesoscale Hydrologic Model mHM). Their quality is assessed by their capacity to reproduce historical streamflow time series. This test phase allows improving the generation technique to obtain synthetic imagery that can be considered a reasonable approximate of unobserved processes consistent with the available climate data, and which will help improve modelling accuracy.Keywords: Remote sensing, Climate reanalysis, Satellite time series, Hydrological modelling
Fostering the next generation of Arctic scientists, from five to 35
Authors: Turton Jenny , El bani Altuna Naima , Weber Charlotte , Dahle Salve , Boine Olsen Nina , Fosshaug Elise , Opheim Katrine , Morales-Aguirre Julia
Published: February 2023

Inspiring the next generation of scientists and science-policy makers is crucial for continued scientific development and to tackle the largest issues currently facing the Arctic and the globe. Outreach in the Arctic has an added importance by promoting future development of northern and Indigenous communities and inspiring educated individuals to remain living and working in the north, thereby providing value creation in the local areas. But at what age should we focus our outreach efforts? And how can we ensure that the children we inspire go onto careers in science and decision making?
Arctic Frontiers is a non-profit organisation based in Tromsø with the purpose of bringing together scientists, business leaders, policy makers and local communities for knowledge-based discussions. Each year, they organise a series of education and outreach activities for a range of audiences, from 'Science for Kids' and 'Science for Schools' for young children to 'Student Forum' and 'Emerging Leaders' for those up to 35 years old. As well as those in formal education (high school and university), outreach is also vital for those outside of academia and education, including in business, cultural fields and the public sector.
The main focus of the outreach and education is the Arctic: a broad and multidisciplinary topic spanning climate change, biodiversity, cultural preservation, sustainable development, energy transition and science-policy interactions. The science and activities that are planned are tailored to each age group. The youngest children focus on experiments and gaging an interest in science. For those in high school, the program lasts three months, from inspiration days to holding a science conference with findings of their research project. Collaborations and funding are necessary for these events to run, and this can alter the amount of scientific outreach as well as numbers and diversity of students they can reach.
The education and outreach components of Arctic Frontiers have been running now for over 10 years. Testimonials and feedback from attendees are largely positive, but efforts should now be made to increase the circle of impact. In this presentation we will focus on how we tailor the outreach to different groups and discuss how we use science at the heart of bringing together different audiences for holistic Arctic discussions. We also welcome feedback on new methods or activities for outreach, to ensure that we see scientific interest from childhood to career.
Solar energy potential assessment on urban rooftops using digital surface models
Authors: Hou Xinyuan , Kazadzis Stelios
Published: February 2023

Rooftop solar photovoltaic (PV) systems have the advantage of producing electricity without air pollution and greenhouse gas emissions, at the same time reducing carbon footprint as well as urban heat island effect. This study aims to assess physical, geographical and economic levels of solar energy potentials in actual atmospheric conditions on urban rooftops, using two municipalities in Athens, Greece as an example. We utilize very high-resolution digital surface models for the computation of clear-sky solar irradiance considering surrounding shadows. For all-sky conditions, cloud and aerosol data from 2012 to 2021 are obtained from the Copernicus Atmosphere Monitoring Service radiation service and the ECMWF Atmospheric Composition Reanalysis 4 product, respectively. The goals are to quantify the effect of solar elevation, the shadowing effect from adjacent buildings and constructions, and the effects of clouds and aerosols on the solar radiation availability on the rooftops and to investigate their interconnections. The spatio-temporal resolution of the analyses ranges from individual rooftop to neighborhood scale (approximately 3000 buildings) and from hourly intervals to ten years periods.The results of the solar potential assessment are made available as a web GIS map for potential public access, intended to aid urban planning and encourage widespread adoption of solar energy in the public and private sectors.
Origin of sedimentary organic matter in Mahakam Delta, Borneo, Indonesia
Authors: Jamaluddin Jamaluddin , Wagreich Michael , Ryka Hamriani
Published: February 2023

The Mahakam Delta is located on the east coast of Kalimantan, the Indonesian portion of Borneo, about 50 kilometres south of the equator, and contains sediments of Miocene to Pliocene age. The Mahakam Delta has a regular lobate morphology typical of a mixed fluvial and tidal delta. Tidal and fluvial currents dominate sedimentation processes. The delta covers about 5,000 km2, including 1,300 km2 of swampy subaerial delta plain, 1,000 km2 of subtidal platform, and 2,700 km2 of prodelta deposits (Allen et al., 1979). Since the middle of the Miocene, the Mahakam Delta has been an important fluvio-deltaic depocenter. It is also a significant hydrocarbon province, and the majority of the oil and gas found there comes from humic sources. The purpose of this study is to unravel the source and origins of organic matter in sediments influenced by tropical fluvio-tidal currents. The studied section is primarily composed of organic-rich shales, coaly shale and coal.  TOC values of shale approximate 1.57 - 9.55 wt.%, coaly shale 6.59 - 19.66 wt.% and coal samples  27.42 – 50.99 wt.% indicating to be a source rock in the study area. According to the classification of Peters and Cassa (1994), the Mahakam delta classifies as good-excellent source rock with the TOC value range 1.57 – 50.99 wt.%. Geochemical analyses of organic-rich sediments from the Miocene indicate that the possible source rocks are delta plain-delta front coals and shales containing predominately type III kerogen organic. Delta front deposits are mostly black, organic-rich mud with plant fragments and silt laminae. Sulfur and siderite nodules indicate anoxic conditions in these sediments. Sediments from the Mahakam Delta plain are a mixture of muds and rare to abundant plant (mangrove swamp, Nypa swamp, and transitional forest). The upper delta plain rainforest may supply sedimentary organic matter. Sedimentary organic matter can be accounted for by the incorporation of produced leaves into waterways through direct leaf failure, slumping of channel banks, and sporadic tidal export. The plants in the lower delta plain make a dense, tangled web of dead Nypa palm petioles and leaves and aerial roots. Sedimentary organic matter in Mahakam deltaic environments comes mainly from delta plain vegetation. Organic matter from the delta plain, mostly degraded plant remains, is incorporated into the deltaic system by tidal channel erosion of Nypa and transitional forest. Vegetal debris like wood and leaves accumulated in situ, preserved by sedimentation, forming thick layer coaly shales and coal beds Geochemical analyses of organic-rich sediments from the Miocene indicate that the potential source rocks are delta plain-delta front coals and shales containing predominately type III kerogen organic matter as having good to excellent potential as gas source rocks. 
EarthNets: An Open Deep Learning Platform for Earth Observation
Authors: Xiong Zhitong , Zhu Xiao Xiang
Published: February 2023

Earth observation (EO) data are critical for monitoring the state of planet Earth and can be helpful for various real-world applications [1]. Although numerous benchmark datasets have been released, there is no unified platform for developing and fairly comparing deep learning models on EO data [2]. For deep learning methods, the backbone networks, hyper-parameters, and training details are influential factors while comparing the performances.. However, existing works usually neglect these details and even evaluate the performance with different training/validation/test dataset splits. This makes it difficult to fairly and reliably compare different algorithms. In this study, we introduce the EarthNets platform, an open deep-learning platform for remote sensing and Earth observation. The platform is based on PyTorch [3] and TorchData. There are about ten different libraries, covering different tasks in remote sensing. Among them, Dataset4EO is designed as a standard and easy-to-use data-loading library, which can be used alone or together with other high-level libraries like RSI-Classification (for image classification), RSI-Detection (for object detection), RSI-Segmentation (for semantic segmentation), and so on. Two factors are considered for the design of the EarthNets platform: the first one is the decoupling between dataset loading and high-level EO tasks. As there are more than 400 RS datasets with different data modalities, research domains, and download links, efficient preparation of analysis-ready data can largely accelerate the research for the whole community. The other factor is to bring advances in machine learning to EO by providing new deep-learning models. The EarthNets platform provides a fair and consistent evaluation of deep learning methods on remote sensing and Earth observation data [4]. It also helps bring together the remote sensing and a larger machine-learning community. The platform, dataset collections are publicly available at https://earthnets.github.io.[1] Zhu, Xiao Xiang, et al. "Deep learning in remote sensing: A comprehensive review and list of resources." IEEE Geoscience and Remote Sensing Magazine 5.4 (2017): 8-36.[2]Long, Yang, et al. "On creating benchmark dataset for aerial image interpretation: Reviews, guidances, and million-aid." IEEE Journal of selected topics in applied earth observations and remote sensing 14 (2021): 4205-4230.[3] Paszke, Adam, et al. "Pytorch: An imperative style, high-performance deep learning library." Advances in neural information processing systems 32 (2019).[4] Xiong, Zhitong, et al. "EarthNets: Empowering AI in Earth observation." arXiv preprint arXiv:2210.04936 (2022).
New approach to evaluate the intensity of ancient human activities, based on organic matter characteristics using Rock-Eval® thermal analysis.
Authors: Aubertin Marie-Liesse , Malou Oscar Pascal , Arroyo-Kalin Manuel , Lombardo Umberto , Chevallier Tiphaine , Oliva Priscia , Delarue Frédéric , Thiesson Julien , Quenea Katell , Sebag David , de Saulieu Geoffroy
Published: February 2023

Archaeological anthrosols constitute a heritage of long-term carbon storage and soil fertility. Their anthropogenic features are affected by the type and intensity of ancient human activities. Human activities can follow a gradation of disturbance intensity, with lower intensity related to a weak human pollution of natural soil, and stronger intensity related to anthropogenic materials inputs (e.g. refuse pits). Soil properties are indeed deeply modified by the addition of objects (e.g. bones, ceramic) and of organic matter with distinct chemical composition and biological stability (e.g. charcoal). The aim of the study was to establish a new analytical approach to distinguish intensities of human activities, based on organic matter characteristics. To this end, we studied intertropical soil profiles (0-120 cm) from Cameroon, Brazil and Bolivia, with spatial or temporal intensity variations of human activities. We used standard compositional parameters (hydrogen index, HI, and oxygen index, OI) and advanced thermal parameters (I-index and R-index) from Rock-Eval® pyrolysis, as well as magnetic susceptibility, to characterize anthrosols.Results demonstrated the potential of Rock-Eval® pyrolysis parameters to identify human activities changes. First, the deviation of I-index (delta-I) between our samples and a reference value from natural sites informed about the intensity of human impacts, allowing for the distinction between artificial infilling of refuse pits and soil profiles with no or few human impacts. Second, positive HI:OI correlation established the importance of charcoal as main organic C source. The magnetic susceptibility informed about the presence of burnt soils in a Brazilian and one of the Bolivian sites. The combination of all these parameters, when represented with soil depth, allowed for the estimation of temporal changes in Brazilian and Bolivian sites. The topsoils were similar for all sites, relative to a low intensity of human activities or to the resumption of natural pedogenesis, thereby alleviating the effects of ancient human activities on organic matter characteristics. In contrast, the subsoils exhibited higher intensities of ancient human activities, with even higher values of intensities in Bolivian sites, thereby evidencing the long-term conservation of their effects on organic matter characteristics.To conclude, anthropogenic activities may durably affect organic matter characteristics in tropical sites, even after several centuries. Beyond being of interest for archaeological research, this new approach raises questions about the long-term consequences of our current human activities.
Climatology of day-to-day temperature changes in Europe
Authors: Huth Radan , Krauskopf Tomáš
Published: February 2023

An important aspect of temperature variability is day-to-day temperature difference. Only a few previous studies have looked into its climatology. It is known that the distribution of day-to-day temperature changes in central Europe is asymmetrical, with large temperature increases prevailing over large decreases in winter, and vice versa in summer. A detailed study into the climatology of day-to-day temperature change and its properties is still missing, however.This study attempts to fill in this knowledge gap. We present climatology of the mean absolute value of day-to-day temperature changes, its standard deviation, values of extreme quantiles, and skewness for Europe in winter and summer. We examine several datasets, including station data (from ECA&D database), an interpolated gridded dataset (E-OBS), and reanalyses (NCEP-NCAR, JRA55, and 20CR). The comparison of various types of datasets allows us to identify their specific behaviour, pointing to potential errors and biases.This contribution is a part of our efforts to describe and understand long-term changes in short-term (intraseasonal) atmospheric variability and their mechanisms.
Geological hiatus surfaces across Africa in the Cenozoic: implications for the timescales of convectively-maintained topography
Authors: Carena Sara , Friedrich Anke , Bunge Hans-Peter
Published: February 2023

Geological maps contain a large amount of information that can be used to constrain geodynamic models, but which has been often overlooked by the geodynamic community. Particularly significant are unconformable geologic contacts at continental scales: what is usually perceived as a lack of data (material eroded or not deposited) becomes instead part of the signal of dynamic topography.We were able to use geological maps to constrain the dynamic processes in the mantle beneath Africa by understanding its Cenozoic elevation history, and by using it to distinguish between different uplift and subsidence scenarios. This was accomplished by mapping the spatio-temporal patterns of geological contacts at the series level using continental-scale geological maps, under the assumption that continental-scale unconformable contacts are proxies for vertical motions and for paleotopography. We also mapped the present-day elevation of marine sediments for each series.We found that significant differences exist in interregional hiatus surfaces. For example, the total unconformable area at the base of the Miocene expands significantly compared to the base of the Oligocene, strongly suggesting that most of Africa underwent uplift in the Oligocene. In southern Africa there are no marine Oligocene or Pleistocene sediments, suggesting that this region reached a high in the Oligocene, subsided in the Miocene and Pliocene, and has been high again since late Pliocene to Pleistocene. More generally, to reproduce the pattern of marine sedimentation in Africa that we mapped, sea level increases between 300 and at least 500 m above present level would be required. These are well in excess of the maximum 150 m eustatic sea level rise that has been postulated by several authors for the Cenozoic. Our results therefore support a dynamic origin for the topography of Africa. Specifically, the time-scale of geologic series (at most a few tens of millions of years) is comparable to the spreading-rate variations in the south Atlantic, which have been linked to African elevation changes through pressure-driven upper mantle flow.
Latewood density and overall ring anatomy responses to temperature in Scots pine explained by carbohydrate diffusion and cellular kinetics
Authors: Friend Andrew , Eckes-Shephard Annemarie , Tupker Quinten
Published: February 2023

Our understanding of wood formation is poor. Key anatomical properties in conifer and ring-porous tree species that have not been explained include the overall anatomy of growth rings (with consistent transitions from low-density earlywood to high density latewood), strong relationships between latewood density and temperature (used for historical temperature reconstructions), the regulation of cell size, and overall growth-temperature relationships. We have developed a theoretical framework based on observations on Pinus sylvestris L. in northern Sweden. These observed anatomical properties emerge from our framework as a consequence of interactions in time and space between the production of new cells, the dynamics of developmental zones, and the distribution of carbohydrates across the developing wood. Here we find that the diffusion of carbohydrates is critical in determining the final ring anatomy, potentially overturning current understanding of how tree growth responds to environmental variability and transforming our interpretation of tree rings as proxies of past climates.
Making InSAR processing hardisks small again: Estimating the impact of Quantized Compressed SAR images on the precision of PS InSAR time series
Authors: Yip Man Wai , Webb A. Alexander G. , González Pablo J.
Published: February 2023

Modern satellites produce massive datasets. So, handling and processing bulk Synthetic Aperture Radar (SAR) imagery often represents a high entry level for researchers to tackle scientific challenges at regional or global scale. SAR imaging has been used as a remote sensing tool for studying Earth’s surface, such as measuring topography, terrain discrimination, forestry, and differential interferometry (InSAR) for monitoring the Earth’s surface deformation at millimetre scale. Due to the growing application of SAR imaging and the advancement of InSAR technique, more SAR satellites have been launched over the years. Moreover, those satellites have increased its temporal and spatial sampling rate, which contributes to the current rapid and massive data volume available for InSAR processing. Storage (on-line and off-line hardisks) requirements for InSAR processing is therefore constantly growing - over the past 7 years, Sentinel-1 SAR data downloaded by users has been increased by 620% (Serco, 2022). In the future, more SAR satellites with higher resolutions will be launched, not only increasing the carbon footprint by storing massive data in energy-intensive data centre, but also putting higher pressure on the computing resources of both the platforms and individual users for its scientific exploitation. In this study, we explored compression algorithms to downsize Sentinel-1 single look complex (SLC) images by 2 to 4 times. 162 ascending SLC images covering an area of around 19,335 km2 over the Pearl River Delta Region in the southern China were used in the test. In order to evaluate the performances of these compressed images for ground deformation monitoring, we compressed SLCs  generated by ISCE, calculate interferograms from compressed SLCs, and then compute time series of surface displacements using StaMPS InSAR processing software. Bulk SLC images can be compressed using the Julia package developed in this study and only decompress during calculation of interferograms, therefore images will not be saved in their expanded format. Our error analysis for signal reconstruction and the processed time-series results suggests that original 32-bit complex images can be can be optimally compressed using different quantization methods, reducing the storage required to handle large processing InSAR tasks. We confirmed that complex radar images retrieved from SAR satellites to be compressed up to a factor of 4 times, and achieving data reduction without sacrificing significant ground displacement precision.
DEM crack propagation using a FEM-DEM bridging coupling
Authors: Voisin-Leprince Manon , Garcia-Suarez Joaquin , Anciaux Guillaume , Molinari Jean-François
Published: February 2023

The behavior of seismic faults depends on the response of the discrete microconstituents trapped in the region between continuum masses, which is usually termed “gouge”. The gouge is a particle region composed of amorphous grains. Conversely, the regions surrounding the gouge can be conceptualized as continua. The study of such system dynamics (slip) requires the understanding of several scales, from particle size to meter scale and above, to properly account for loading conditions. Our final objective in this study is to assess to what extent we can understand friction by leveraging an analogy to fracture. Dynamic friction between sliding surfaces resembles a dynamic mode-II crack, but this equivalence is brought into question when granularity at the interface is considered. Based on the theory of linear-elastic fracture mechanics (LEFM), a stress concentration should be observed at the rupture front if indeed friction can be modeled with the toolkit of LEFM.Simulating this system numerically remains a challenge, as, in order to capture proper physics, both the continuum and discrete aspects of the system must be harmoniously incorporated and coupled into a single model. An energy-based coupling strategy between the Finite Element Method (FEM), used to resolve the continuum portions, and the Discrete Element Method (DEM), to model the granularity of the interface, is used [2]. In this exploratory study, we begin by modeling a medium with strong inter-granular cohesion [1]. The use of the coupling ensures a large enough effective domain to control nicely the crack propagation.  The linear-elastic properties of both DEM and FEM portions are therefore matched to avoid wave reflections. Both mode-I and mode-II cracks are considered.
Impact of iodine injections from the suface and the small satellites using iodine propulsion system in the upper atmosphere on ozone depletion
Authors: Feng Wuhu , Plane John , Chipperfield Martyn , Saiz-Lopez Alfonso , Booth Jean-Paul , McClory Sarah , Kinnison Doug
Published: February 2023

Iodine has the potential to cause stratospheric ozone depletion.  However, there is still significant uncertainty concerning the magnitude of its effect, ranging from a few percent to 10% based on the literature studies. Moreover, these studies have only considered that up to  0.77±0.10 per trillion by volume (pptv) total inorganic iodine is entrained into the stratosphere from the surface emissions. Recently the first 12U CubeSat using the iodine electric propulsion was launched in November 2021 into an orbit at ~480 km. The system produces iodine ions after vaporizing solid iodine. Thus the launch of nanosatellites using iodine propulsion will inject gas-phase iodine species into the thermosphere, which upon re-entering the atmosphere could potentially cause depletion of the ozone layer and consequently impact climate. Here we use the 3-D Whole Atmospheric Community Climate Model (WACCM) to investigate stratospheric ozone depletion due to the launch of small satellites (e.g., CubeSats) with an iodine propulsion system and understand the potential risks caused to stratospheric ozone . We have separted the contribution to the stratospheric ozone depletion from the surface emissions of Iodine and its injection from the upper atmosphere. We have performed a number of model sensitivity runs with different additional scenarios of iodine injection at 120-140 km to explore the potential  stratospheric ozone depletion from small satellites powered in this way. For the base case scenario in the current condition (for example year 2014), a steady-state nanosatellite launch rate of 20,000/year (e.g., 8 tons of I+ injected), the perturbation to the total column ozone is negligible. However, a 10 or 100-fold increase in the mass of iodine launched into near-Earth orbit will cause significant ozone depletion. This study quantifies the extent to which the injection of iodine into the thermosphere can deplete stratospheric ozone, which will be a useful guide for limiting the population of satellites with iodine propulsions systems in low Earth orbit. The impact of iodine for the extreme large ozone depletion years (for example, 2020)  and future scenarios of the results will be also discussed.
Do observations show that rare extremes increase relatively more compared to common extremes?
Authors: van der Ent Ruud , Doekhie Maarten , Fokkema Mees , Zhou Wenyu , van de Giesen Nick , Gründemann Gaby
Published: February 2023

In a recent analysis of 25 CMIP6 models, Gründemann et al. (2022, https://doi.org/10.1038/s43247-022-00558-8) have shown that by the end of this century, daily land rainfall extremes could increase in magnitude between 10.5% and 28.2% for annual events (1 year return period), and between 13.5% and 38.3% for centennial events (100 year return period). The higher relative increase for larger return period was consistent for all climate models and scenarios. However, this study was solely based on model output and so far, this finding was not validated by observations. Using a large sample of stations with long time series, we analyzed whether the rare extremes have indeed been increasing relatively more because of global warming. Moreover, we analyzed sensitivity to the choice of time period, return period and rainfall duration.
Evaluating long range middle atmospheric variability for global infrasound monitoring
Authors: Le Pichon Alexis , Listowski Constantino , Hupe Patrick , Ceranna Lars
Published: February 2023

Global scale infrasound observations confirm that the detection capability of the International Monitoring System (IMS) deployed to monitor compliance with the Comprehensive Nuclear-Test ban Treaty (CTBT) is highly variable in space and time. Previous studies estimated the radiated source energy from remote observations using empirical yield-scaling relations accounting for the along-path stratospheric winds. However, these relations simplified the complexities of infrasound propagation as the wind correction applied does not account for an accurate description of the middle atmosphere along the propagation path. In order to reduce the variance in the calculated transmission loss, massive frequency and range-dependent full-wave propagation simulations are carried out, exploring a wide range of realistic atmospheric scenarios. Model predictions are further enhanced by incorporating fine-scale atmospheric structures derived from a two-dimensional horizontal wave number spectrum model. A cost-effective approach is proposed to estimate the transmission losses at distances up to 4,000 km along with uncertainties derived from multiple gravity wave realizations. In the context of the future verification of the CTBT, this approach helps advance the development of network performance simulations in higher resolution and the evaluation of middle atmospheric models at a global scale with limited computational resources.