bluuebunny/crossref_metadata_2025 huggingface dataset:
Groundwater recharge using a subsurface irrigation system: A technical feasibility study
Authors: Sultana Rebecca , Werban Ulrike , Vienken Thomas
Published: March 2022

In view of humanity’s rising demand for water and rapidly depleting aquifers, managed aquifer recharge (MAR) is a proven approach to replenish groundwater resources. Different MAR techniques exist. Among them, surface spreading methods are widely used in Europe. In this method, surface water is spread over basins, furrows or trenches where water percolates through vadose zone to recharge the groundwater. This method is highly effective. However, it is associated with a number of challenges, e.g. high space requirements, installation along with removal expenses, high evaporation rate and, foremost, limited availability of the used land for other purposes during operation. A subsurface irrigation system can be an alternative solution to mitigate major limitations of surface spreading methods. However, its technical viability needs to be determined. In this research, infiltration characteristics of a subsurface irrigation system in the vadose zone was determined numerically, using Hydrus 2D/3D model for sandy soil. In addition, a test-size-scale one cubic meter soil tank experiment with a uranine tracer was set up to evaluate the model results. The wetting front velocity and pattern was traced using EC-5 soil moisture sensors and a fixedly positioned direct push optical image profile (OIP) probe. Experiments revealed that the subsurface irrigation system infiltrated 1.14 L/h/m in the considered sandy soil with a maximum percolation velocity of 9.84 cm/hr. The numerical and experimental outcomes are in good agreement and are now used to design a field application to practically assess the long-term performance of the subsurface irrigation system for managed aquifer recharge.

 

 
Morphological evolution of volcanic crater through eruptions and instabilities: The case of Ol Doinyo Lengaï since the 2007-08 eruption
Authors: Tournigand Pierre-Yves , Smets Benoît , Laxton Kate , Dille Antoine , Dalton-Smith Michael , Schachenmann Gian , Wauthier Christelle , Kervyn Matthieu
Published: March 2022

Ol Doinyo Lengaï (OL) in north Tanzania is the only active volcano in the world emitting natrocarbonatite lavas. This stratovolcano (2962 m a.s.l) is mostly characterized by effusive lava emissions since 1983. However, on the 4th of September 2007, explosive events marked the beginning of a new eruptive style that lasted until April 2008. This new phase involved short-lived explosive eruptions that generated volcanic ash plumes as high as 15 km during its paroxysmal stage. This explosive activity resulted in the formation of a 300 m wide and 130 m deep crater in place of the growing lava platform that had filled the crater since 1983. Since then the effusive activity at OL resumed within the crater and has been partially filling it over the last 14 years. Due to the remote location of the volcano there is a lack of monitoring of its activity and, hence, its eruptive and morphological evolution over the last years is not well constrained (e.g., emission rates, number of vents, unstable areas). This absence of monitoring, preventing the detection of features, such as instabilities of the summit cone, could have hazard implications for the tourists regularly visiting the summit area.

In this study, we quantify the evolution of OL crater area over the last 14 years by reconstructing its topography at regular time interval. We collated several sources of optical images including Unoccupied Aircraft Systems (UAS) images, videos and ground-based pictures that have been collected over the period 2008-2021 by scientists and tourists. Those data have been sorted by year and quality in order to reconstruct the most accurate topographical models using Agisoft Metashape Pro, a software for Structure from Motion (SfM) photogrammetry, and CloudCompare a 3D point cloud processing software. This enables estimating the emitted volume of lava, the emission rate and the remaining crater volume available before crater overflow. It also allows identifying punctual events, such as hornito formation or destruction, and partial crater collapses. Our results indicate that the main lava emission area has repeatedly moved over the years within the crater floor and that OL’s effusion rate has been increasing over the last few years, with more than two times higher lava emission in the period 2019-2021 compared to 2017-2019. Assuming a similar lava effusion rate in the coming years, the crater could again be filled within the next decade leading to new lava overflows. There is thus a need for periodic assessment of the situation at OL. New cost- and time-effective photogrammetry techniques, including UAS and SfM processing, offer a solution to improve the monitoring of such remote volcanoes.
A link between turbulent cascade and gyrotropic pressure instabilities in compressible and magnetized fluids. 
Authors: Simon Pauline , Sahraoui Fouad
Published: March 2022

In recent years, the Kolmogorov's statistical formalism of exact law that describes incompressible hydrodynamic turbulence, has been extended to compressible magnetized fluid described by isothermal or polytropic closure. Such exact laws permit an evaluation of the energy cascade rate, assumed within this formalism to be equivalent to the dissipation rate. Its estimation in the solar wind can help to better understand particle heating in such collisionless media. But previous exact laws are insufficient in a system led by pressure anisotropy. We propose a general exact law of Hall-MHD turbulence based on models with a pressure tensor that allows us to study various known equations of state as particular limits, derive a new one corresponding to the CGL (i.e., gyrotropic pressure tensor), and correlate the cascade rate to instable plasma conditions. In the incompressible MHD limit we provide a generalization of the Politano & Pouquet law to pressure-anisotropic plasmas.
The relationship of the displacement of the north magnetic pole with volcanic activity in the Yellowstone caldera
Authors: Zhumabayev Beibit , Vassilyev Ivan
Published: March 2022

The paper considers the reason for the displacement of the magnetic axis relative to the axis of rotation of the Earth for the case of the quartz nature of the dipole magnetic field. A model based on a ring with a current with an uneven distribution of charges along the circumference of the ring is considered. It is shown that the magnetic axis shifts from the axis of rotation towards a greater concentration of charges and, conversely, with a decrease in the concentration of charges. The issue of reducing the number of gravity-oriented quartz crystals in areas of volcanic activity is discussed. The temporal correlation of the beginning of accelerated drift of the Earth's north magnetic pole with the development of volcanic and tectonic activity in the Yellowstone caldera is shown. Attention is drawn to the fact that the Earth's north magnetic pole is shifting towards the geographical pole relative to the geographical coordinates of the Yellowstone caldera.
GGOS Bureau of Products and Standards: Description and Promotion of Geodetic Products
Authors: Angermann Detlef , Gruber Thomas , Gerstl Michael , Heinkelmann Robert , Hugentobler Urs , Sanchez Laura , Steigenberger Peter , Heki Kosuke , Schuh Harald , Sehnal Martin
Published: March 2022

The Bureau of Products and Standards (BPS) is a key component of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG). It supports GGOS in its goal to provide consistent geodetic products needed to monitor, map, and understand changes in the Earth’s shape, rotation, and gravity field. In addition to the operational structure, the Committees “Earth System Modeling” and “Essential Geodetic Variables” as well as the Working Group “Towards a consistent set of parameters for the definition of a new Geodetic Reference System (GRS)” are associated to the BPS. This contribution presents the structure and role of the BPS. It highlights some of the recent activities, which are focused on the classification of geodetic products and on the generation of user-friendly product descriptions to support the establishment of a comprehensive Internet portal for Geodesy under the responsibility of GGOS. The GGOS website www.ggos.org serves as an “entrance door” and information platform to geodetic data and products, and should become an essential tool to make these data and products easier findable and accessible. With this, GGOS is contributing to address different user needs (e.g., geodesists, geophysicists, other geoscientists and further customers) and to make other disciplines and society aware of Geodesy and the importance of its products.
Comparing Sentinel-5P TROPOMI NO2 column observations with the CAMS-regional air quality ensemble 
Authors: Eskes Henk , Douros John , van Geffen Jos , Boersma Folkert , Compernolle Steven , Pinardi Gaia , Blechschmidt Anne , Peuch Vincent-Henri , Colette Augustin , Veefkind Pepijn
Published: March 2022

The Sentinel-5P TROPOMI instrument provides unique observations of atmospheric trace gases at a high resolution of about 5 km with near-daily global coverage, resolving individual sources like thermal power plants, industrial complexes, fires, medium-scale towns, roads and shipping routes. These datasets are especially well suited to test high-resolution regional-scale air quality (AQ) models and provide valuable input for regional emission inversion systems. In Europe, the Copernicus Atmosphere Monitoring Service (CAMS) has implemented an operational regional AQ forecasting capability for Europe based on an ensemble of 7 up to 11 European models. In the presentation we show comparisons between TROPOMI observations of nitrogen dioxide (NO2) and the CAMS AQ forecasts and analyses of NO2. We discuss the different ways of making these comparisons, and present the quantitative results for time series for regions and cities between May 2018 to March 2021, for summer and winter months and individual days. We demonstrate the importance of the free tropospheric contribution to the tropospheric column, and include profiles from the CAMS configuration of the ECMWF’s global integrated model above 3 km altitude in the comparison. The models generally capture the fine-scale daily and averaged features observed by TROPOMI in much detail. In summer, the quantitative comparison of the NO2 tropospheric column shows a close agreement, but in winter we find a significant discrepancy in the average column amount over Europe. Recently a new TROPOMI NO2 reprocessing with processor version 2.3.1 has become available, and impact of this new version on the comparisons is discussed. 

As spin-off, we present a new TROPOMI NO2 level-2 data product for Europe, based on the replacement of the original TM5-MP generated global a priori profile (1x1 degree resolution) by the regional CAMS ensemble profile at 0.1x0.1 degree resolution. This a-priori replacement leads to significant changes in the TROPOMI retrieved tropospheric column, with typical increases at the emission hotspots in the order of 20%. 

The European NO2 product is compared with ground-based remote sensing measurements of 6 PANDORA instruments of the Pandonia global network and 8 MAX-DOAS instruments. As compared to the standard S5P tropospheric NO2 column data, the overall bias of the new product is smaller owing to a reduction of the multiplicative bias linked to the profile shape.
Growth of fractures with constricted opening
Authors: Pasternak Elena , Dyskin Arcady
Published: March 2022

Growth of real fractures is characterised by interruptions and local overlapping caused by rock heterogeneities. The interruptions and loci of overlapping can work as bridges distributed all over the fracture that connect opposite surfaces of the fracture [1]. These bridges constrain the crack opening and thus mitigate the dependence of the Mode I stress intensity factor of the fracture length (radius). In the case of hydraulic fractures, constraining the opening also affects the fluid (e.g. fracturing fluid) flow through the fracture.

The effect of bridges can be characterised by a characteristic length – the constriction length. When the fracture size is small compared to the constriction length, the fracture behaves similarly to a conventional Model I crack of the same configuration. Alternatively, when the fracture size is much greater than the constriction length both the  average fracture opening and the Mode I stress intensity factor become constant. This restricts the ability of the fracture to growth in unstable manner or dynamically.

The effect of constriction is even more pronounced in the case when the fracture gets open in the displacement-controlled mode. In this case the dependence of the stress intensity factor of disc-like fracture on the fracture radius is no longer monotonic. The stage of decrease of the stress intensity factor with the fracture radius leads to the emergence of stable fracture growth when increase in the displacement is required to maintain fracture propagation. It is important that without taking the constriction into account the corresponding stage of stable fracture propagation can be taken for the effect of rock heterogeneity.

The theory developed is essential for predicting and monitoring growth of Mode I fractures, in particular hydraulic fractures.

He, J., Pasternak, E. and A.V. Dyskin, 2020. Bridges outside fracture process zone: Their existence and effect. Engineering Fracture Mechanics, 225, 106453.

Acknowledgement. The authors acknowledge support from the Australian Research Council through project DP190103260.
Using a process-based dendroclimatic proxy system model in a data assimilation framework: a test case in the Southern Hemisphere over the past centuries
Authors: Rezsöhazy Jeanne , Dalaiden Quentin , Klein François , Goosse Hugues , Guiot Joël
Published: March 2022

Tree-ring widths represent the most commonly used proxy to reconstruct the climate of the last millennium at high resolution, thanks to their large-scale availability. The approach often relies on a relationship between tree-ring width series and climate estimated on the basis of a linear regression. The underlying linearity and stationarity assumptions may be inadequate. Dendroclimatic process-based models, such as MAIDEN (Modeling and Analysis In DENdroecology), may be able to overcome some of the limitations of the statistical approach. MAIDEN is a mechanistic ecophysiological model that simulates tree-ring growth starting from surface air temperature, precipitation and CO2 concentration daily inputs. In this study, we successfully include the MAIDEN model into a data assimilation procedure as a proxy system model to robustly compare the outputs of an Earth system model with tree-ring width observations and provide a spatially-gridded reconstruction of continental temperature, precipitation and winds in the mid to high latitudes of the Southern Hemisphere over the past centuries. More specifically, we evaluate the benefits of using process-based tree-growth models such as MAIDEN for reconstructing past climate with data assimilation compared to the commonly used linear regression. The comparison of the reconstructions with instrumental data indicates an equivalent skill of both the regression- and process-based proxy system models in the data assimilation framework. Nevertheless, the MAIDEN model still brings important advantages that could result in more robust reconstructions beyond the instrumental era. Moreover, improvements continuously made in such models or in their calibration procedure also offer encouraging perspectives. Important steps have thus been made to demonstrate that using a process-based model like MAIDEN as a proxy system model is a promising way to improve the large-scale climate reconstructions with data assimilation.
Field hydrological monitoring in vineyards for the analysis of shallow slope failures susceptibility and water stress phenomena
Authors: Bordoni Massimiliano , Vivaldi Valerio , Panza Giacomo , Meisina Claudia
Published: March 2022

Vineyards cultivated in steep terrains are widespread all over the world, constituting the main economic activity and landscape element in many territories. However, these vineyards can be affected by several problems, mainly due to water stress in dry periods and shallow slope instabilities during very intense thunderstorms or prolonged rainy periods. Both these problems provoke significant damages to the grapevines and the implants, together with a general loss of fertility and biodiversity in the soil horizons. Sustainable managements of the inter-rows, which limit or exclude tillage operations in soils, can represent a useful solutions to reduce the phenomena of water stress and of the triggering of shallow slope failures. Since they could modify the soil hydrological behaviors, a continuous-in-time soil hydrological monitoring is required to highlight differences on soil moisture along different dry and wet periods between vineyards managed in different ways. The aim of this work is, then, to present the results of a field hydrological monitoring carried on vineyards managed in different ways to highlight differences on soil water content trends in different seasons. The results of this monitoring can infer to different responses in terms of possible water stress phenomena and susceptibility towards shallow slope failures. Some test-sites were selected in northern Italian Appenines, in two important wine districts very prone to water stress and slope instabilities. The field monitoring is carried out with a set of soil water content sensors, installed at different depths in the soil profile and in inter-rows characterized by different soil managements, both with traditional tillages and sustainable practices (permanent grass cover, alternation between grass cover). Soil water content trends collected at the same depth in different test-sites allow to highlight the impact of the different practices in soil hydrological behaviors and on the probability of low soil moisture (predisposing factor to water stress) or saturated conditions (predisposing factor to slope instaibilities). This work is realized in the frame of VIRECLI (funded by Regione Lombardia) and LIFE-DRIVE projects.
Evidence of volcanic debris avalanche propagation dynamics from sedimentological analysis of the Tenteniguada and Abona deposits, Canary Islands
Authors: Makris Symeon , Roverato Matteo , Lomoschitz Alejandro , Cole Paul , Manzella Irene
Published: March 2022

Debris avalanches (DA) are large landslide events characterised by long runouts and high mobility that poses a great hazard to communities close to volcanoes. Although many theories have been proposed to explain the excessive runout phenomenon, the mechanisms enabling the mobility remain unresolved and poorly constrained. As a result, it is still challenging for models and theoretical concepts to encompass DA deposit field observations.

DA deposits are complex; however, detailed study of their sedimentary architecture can provide information regarding their propagation processes. In this study, the deposits of two DAs in the Canary Islands: Tenteniguada DA, located on the east of Gran Canaria; and Abona DA on the southeast of Tenerife have been examined. Although they are located in nearby volcanic islands they occurred in different environments with different triggering processes, scale, material and their deposits suggest different propagation rheology. A detailed field study of the deposits was carried out in September 2021, mapping their facies and feature distribution and sedimentology. Structure from motion photogrammetry methodology has been used to generate high accuracy 3D models of outcrops and sample windows to quantify facies distribution. The data collected allow for evaluation of the effects of material properties, substrate and its geometry, and to assess aspects of the dynamics of the DAs. Therefore, it was possible to generate conceptual models for the transport and emplacement mechanisms of the two events corresponding to the observations and to relate them to the two debris avalanche distinctive characteristics by comparison.

In the Tenteniguada DA deposit, the degree of disaggregation is low, with large portions of the original edifice preserved along with their original stratigraphy, although displaced relative to each other by brittle deformation. In contrast, Abona DA is much more disaggregated. Monolithological blocks are microfractured and cataclased, and original stratigraphy is not preserved. There is no evidence of brittle deformation. The highly comminuted material has been elongated in a fluidised spreading flow, achieving a long runout on an erodible pumice substrate. Conversely, the Tenteniguada DA did not fully transition from a slide to a flow and has not generated a long runout while propagating in an active fluvial ravine. These findings suggest that the behaviour and the distribution of stresses was very different during propagation, owing to the properties and volume of the material in the flow and potentially the substrate properties and triggering mechanisms.

The present study highlights how the field examination of sedimentological, morphological, and structural features is vital in fully understanding DA propagation and emplacement mechanisms.
Assessing Long-Term Field Experiments of Europe through a geospatial data infrastructure
Authors: Donmez Cenk , Grosse Meike , Hierold Wilfried , Schmidt Marcus
Published: March 2022

Long-Term Field Experiments (LTEs) are agricultural experiments for monitoring soil and crop properties in changing climate conditions and different management practices. These trials were set up on various soil textures and types to reveal the effects of management and environment on crop production and soil resources. Although the LTEs are essential infrastructures for sustainable soil yield and use, LTE-related information was dispersed, thus not easy to find. To close this research gap, we compiled and analyzed the meta-information of the LTEs across Europe and their spatial representation in a geospatial data infrastructure, including a data repository and an LTE overview map developed within the framework of the BonaRes project (BonaRes 2021; Grosse et al. 2021). During the research, LTEs with a minimum duration of 20 years were identified, and the meta-information was collected by extensive literature review and factsheets. In total, 405 LTEs in Europe were identified, clustered in different categories (management operations, land use, duration, status, etc.), and these clusters were geospatially analysed to provide inputs for the agricultural industry, scientists and decision-makers. LTEs from 25 countries were utilized including Germany, where the oldest LTE started in 1843. The majority of the LTEs have the fertilization treatment, followed by crop rotation and tillage. The results will help to develop a mutual agricultural management framework by revealing the LTE potential internationally. The geospatial data structure will contribute to scaling up the management practices from site to landscape-level for increasing the adaptation of agricultural systems to climate change.

Key Words: Long-Term Field Experiments, BonaRes, Europe, soil science, GIS.

References

BonaRes (2021). Long-term Experiments in Europe. Overview of long-term Experiments. https://lte.bonares.de

Grosse, M., Ahlborn, M.C., Hierold, W. (2021). Metadata of agricultural long-term experiments in Europe exclusive of Germany. Data in Brief 38, https://doi.org/10.1016/j.dib.2021.107322

 
Theoretical explanation for the formation of zebra stripes in the inner radiation belts despite the absence of electric or magnetic field fluctuations.
Authors: Osmane Adnane
Published: March 2022

Zebra stripes are structured peaks and valleys observed on spectrograms of protons and energetic electrons trapped in the inner radiation belts. They have been observed since the 1960s and even though they are transient structures, statistical studies have shown that they are commonly observed and correlated with geomagnetic Kp and Dst indices. Since their discovery, various mechanisms relying on wave-particle interactions have been suggested to explain the formation of zebra stripes. More recently, Lejosne and Roederer (JGR, 121, 2016) have presented a kinematic argument (supported with numerical results) with less constraints than models relying on drift-orbit mechanisms. In this communication, we present a theoretical derivation of zebra stripes from first principles and demonstrate that 1) their formation has a kinematic origin, and 2) that it does not require the presence of electric or magnetic field fluctuations. However, we show that the inclusion of electric or magnetic field fluctuations does not prevent the formation of zebra stripes, and our analysis therefore provides an explanation as to why simulations of drift orbit processes have been able to reproduce zebra stripes patterns.
Structure induced vortices control anomalous dispersion in porous media
Authors: de Anna Pietro , Bordoloi Ankur , Scheidweiler David , Dentz Marco , Bouabdellaoui Mohammed , Abbarchi Marco
Published: March 2022

Natural porous systems, such as soil, membranes, and biological tissues comprise disordered structures characterized by dead-end pores connected to a network of percolating channels. The release and dispersion of particles, solutes, and microorganisms from such features is key for a broad range of environmental and medical applications including soil remediation, drug delivery and filtration. Yet, the role of microscopic structure and flow for the dispersion of particles and solutes in such disordered systems has been only poorly understood, in part due to the stagnant and opaque nature of these microscopic systems. Here, we use a microfluidic model system that features a pore structure characterized by dead-ends to determine how particles are transported, retained and dispersed.  We observe strong tailing of arrival time distributions at the outlet of the medium characterized by power-law decay with an exponent of 2/3. Using numerical simulations and an analytical model, we link this behavior to particles initially located within dead-end pores, and explain the tailing exponent with a hopping and rolling mechanism along the streamlines inside vortices within dead-end pores. These dynamics are quantified by a stochastic model that predicts the full evolution of arrival times. Our results demonstrate how microscopic flow structures can impact macroscopic particle transport.
Assessing the elements at risk in volcanic areas by combining deep convolutional neural network and multispectral satellite images
Authors: Corradino Claudia , Pious Anu , Amato Eleonora , Torrisi Federica , Bucolo Maide , Fortuna Luigi , Del Negro Ciro
Published: March 2022

Volcanic eruptions are spectacular but dangerous phenomena. Depending on their magnitude and location, they also have the potential for becoming major social and economic disasters. Some of the most important volcanic events include ash fallout, lava flows, and related phenomena, such as volcanic debris avalanches and tsunamis. The ongoing demographic congestion around volcanic structures, such as Mount Etna, increases the potential risks and costs that volcanic eruptions represent and leads to a growing demand for implementing effective risk mitigation measures. To fully evaluate the potential damage and losses that a volcanic eruption disaster may cause, the distribution and characterization of all the exposed elements must be considered. Over the past decades, advances in satellite remote sensing and geographic information system techniques have greatly assisted the collection of land cover data. However, assessment of the elements at risk is a lengthy and time-consuming process. In fact, usually data including all exposed elements and land uses are gathered from several Institutional web portals and very high-resolution satellite imagery, not freely available, manipulated by operators. Here, we propose a deep learning approach to automatically identify the elements at risk in high spatial resolution satellite images. In particular, a Convolutional Neural Network (CNN) model is adopted to classify land use and land cover in volcanic areas thus allowing to carefully assess the total exposure by using freely available satellite images. A retrospective analysis is conducted on Mount Etna highlighting changes in the exposure over the last decade.
Building a GIC forecasting tool based on geomagnetic and solar wind data: challenges and future avenues
Authors: Bailey Rachel L. , Leonhardt Roman , Möstl Christian , Beggan Ciaran , Reiss Martin , Bhaskar Ankush , Weiss Andreas
Published: March 2022

Measurements of geomagnetically induced currents (GICs) in the Austrian power transmission grid have been carried out since 2014 at multiple locations. Following an analysis of the scales of GICs across the grid, we now look into forecasting the GICs from incoming solar wind data. Using nearby geomagnetic field measurements stretching back 26 years, we can estimate the local geoelectric field and consequently the GICs over longer time periods. We apply a machine learning method based on recurrent neural networks to this dataset combined with solar wind data as input. In this talk, we present the final method to forecast both the local geoelectric field E and the GICs in substations in the Austrian power grid, with our model results being compared to GIC measurements from recent years. We will discuss the current status of the model, outline limitations, and consider future applications.
Single-frequency GNSS-IR for estimating snowpack height with consumer grade receivers and antennas
Authors: Graldi Giulia , Rover Simone , Vitti Alfonso
Published: March 2022

Ground and space based GNSS-IR (Interferometric Reflectometry) has been used in the last 20 years for characterizing the Earth Surface, together with other remote sensing techniques. Among the physical quantities which can be monitored using these techniques, the characterization of the snow cover is of particular interest since it is an important source of freshwater. The increase of the global temperature due to anthropogenic climate changes is threatening the seasonal recharging, and for this reason monitoring the snow cover is crucial. Ground based GNSS-IR can be used for obtaining information on the height of the snowpack, with a precision of 0.04 m by using geodetic-grade GNSS instruments (such those involved in Continuously Operating Reference Stations - CORS). In the present study, the sensitivity of the retrieval of the snowpack height from data acquired with low cost non-geodetic grade instruments with the GNSS-IR technique is evaluated. The analysis is applied to a flat alpine area in the Lavarone plateau in the Province of Trento, Italy (1400 m above sea level), where GNSS field campaigns were carried out in 2018, 2019 for short time periods (90, 120 minutes) due to constraints of the study area. Single-frequency GPS observations were collected with u-blox M8T GNSS receivers and patch u-blox and Tallysman antennas. Leica antenna and receiver were also used for collecting GPS data in double frequency, in order to acquire reference data with geodetic grade instruments. Given the characteristics of the area, it is possible to consider that GPS signals reflect with specular reflection, and thus modelling the Signal to Noise Ratio (SNR) as a function of the distance between the reflecting snow surface above solid ground and the antenna. Multipath frequency associated with snowpack height is retrieved by applying the Lomb Scargle Periodogram on SNR data. The results show that, by applying GNSS-IR technique to data acquired with low-cost receivers and antennas, it is possible to retrieve the height of the snow pack with a standard deviation of about 0.05 m. This demonstrates the feasibility of GNSS-IR also with non-geodetic grade instruments.
Causes of the weak relationship between modeled Last Glacial Maximum cooling and climate sensitivity, with consequences for emergent constraints
Authors: Renoult Martin , Sagoo Navjit , Zhu Jiang , Mauritsen Thorsten
Published: March 2022

The use of paleoclimates to constrain the equilibrium climate sensitivity (ECS) has seen a growing interest. In particular, the Last Glacial Maximum (LGM) and the mid-Pliocene Warm Period have been used in emergent constraint approaches using simulations from the Paleoclimate Modelling Intercomparison Project (PMIP). Despite lower uncertainties regarding geological proxy data for the LGM in comparison with the Pliocene, the robustness of the emergent constraint between LGM temperature and ECS is weaker at both global and regional scales. Here, we investigate the climate of the LGM in models through different PMIP generations, and how various factors contribute to the spread of the model ensemble. Certain factors have large impact on an emergent constraint, such as state-dependency in climate feedbacks or model-dependency on ice sheet forcing. Other factors, such as models being out of energetic balance and sea-surface temperature not responding below -1.8°C in polar regions have a restricted influence. We quantify some of the contributions and show they mostly have extratropical origins, which contribute to a weak global constraint, and remotely impact tropical temperatures. Statistically, PMIP model generations do not differ substantially, unlike what has been previously suggested. Furthermore, we find that the lack of high or low ECS models in the ensembles critically limits the strength and reliability of the emergent constraints.
Car DOAS Measurements of NO2, HCHO and SO2 in South Korea during GMAP 2021
Authors: Dörner Steffen , Lange Kezia , Richter Andreas , van Roozendael Michel , Wagner Thomas
Published: March 2022

South Korea’s Geostationary Environment Monitoring Spectrometer (GEMS) instrument was launched in February 2020 for monitoring of air quality above Asia on an hourly basis. During multiple validation campaigns the data quality of GEMS is being evaluated. Between September and November 2021, the GEMS Map of Air Pollution (GMAP 2021) campaign was supported by mobile car DOAS measurements with two main goals: Determining the general agreement between satellite and ground based measurements with a focus on the intra-pixel variability and assessing the nitrogen oxides (NOx) emission strength of Seoul.

Mobile zenith sky DOAS observations from three instruments are combined and analyzed for Nitrogen Dioxide (NO2), Formaldehyde (HCHO) and Sulphur Dioxide (SO2). Emission estimates are performed for NO2 only, as the signal-to-noise of the other trace gases is too low. For the intra-pixel variability study, direct comparisons with NO2 vertical column densities as derived from the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator (GCAS, operated by NASA) and GEMS measurements are performed.
A Causality-guided Approach for Predicting Future Changes in Extreme Rainfall over China Using Known Large-scale Modes
Authors: Ng Kelvin S. , Leckebusch Gregor C. , Hodges Kevin
Published: March 2022

Over the past few decades, while several advancements in improving the performance of global climate models (GCMs), such as predicting mean climate,  have been made, predicting extreme rainfall events related to Mei-yu fronts (MYFs) and tropical cyclones (TCs) remains an open challenge. This is partially due the coarse spatial resolution of the GCMs that restricts their ability to represent extreme events and the associated processes on relevant spatial scales. This poses a problem for stakeholders as a failure to take appropriate precautionary action before the occurrence of extreme events can have disastrous consequences. Although the spatial resolutions of typical GCMs are too coarse to simulate extreme precipitation accurately, they are more likely to be able to simulate large-scale climate modes (LSCMs) better. Given that the activities of MYFs and TCs are linked to LSCMs, we can make use of these causal connections between LSCMs and extreme rainfall associated with MYFs/TCs to construct useful prediction models. This can then be applied to the outputs of climate GCM simulations to increase our capability in predicting extreme rainfall in the future.

In this presentation, we demonstrate a novel technique based on causality-guided statistical models (CGSMs) to assess the projected future changes of extreme rainfall associated with MYFs and TCs over China using the CMIP6 historical and SSP585 scenario simulations for four selected models. First, we show that CGSMs, which are constructed using historical observations and reanalysis, have good performance in modelling historical observations. Then we compare extreme rainfall related to MYFs/TCs from the CMIP6 historical direct output of the selected models with the CGSMs predictions. Our results show that the climatological patterns of CMIP6 direct historical outputs are different to the observed climatological patterns. Yet, CGSMs driven by CMIP6 LSCMs can produce similar patterns as the observed climatology. For the projected change under the SSP585 scenario, projections based on CGSMs provide a more coherent picture than CMIP6 direct model outputs. This shows the potential of causality-guided approach in coarse resolution climate model outputs. The implication and potential use of this approach is also discussed.
Triggers and deformation mechanism study of reservoir landslide through multi-fields information interpretation
Authors: Zhang Lei
Published: March 2022

Due to the construction of Three Gorges Dam, many old landslides have been revived with the impoundment of reservoir water, which pose great threaten to the lives of residents. Deformation observed in a reservoir landslide is the result of a complex multi-field and dynamic evolution process. In order to gain a comprehensive understanding of the deformation mechanism and evolution process of a reservoir landslide, multi-fields information need to be monitored. Taking Majiagou landslide located at Three Gorges Reservoir Region (TGRR) as an example, a Distributed fiber optic sensing (DFOS) based monitoring system was developed and implemented. The multi-fields information including seepage (rainfall, water level, pore water pressure), deformation and strain-stress variation were monitored in real time. Through analyzing the recorded data with grey correlation analysis method, the factors that trigger the deformation of Majiagou landslide were identified. By further linking the mechanical parameters of soil with seepage field, the deformation mechanism was revealed as well. This paper has provided an advanced multi-fields information monitoring and data interpretation method, which can be widely adopted in reservoir landslide study. 
L1 observations and geoeffectivity consecutive to the frontside halo coronal mass ejections (CMEs) of year 2002
Authors: Grison Benjamin , Cornilleau-Wehrlin Nicole , Bocchialini Karine , Schmieder Brigitte
Published: March 2022

Bocchialini et al. (2018) showed that among the 28 frontside halo coronal mass ejections (CMEs) with a visible source seen on the Sun in 2002, 21 are unambiguously associated with sudden storm commencements (SSCs). Based on velocity comparisons (LASCO, L1, and ballistic velocities), we look for association between these 28 halo CMEs and shock-like discontinuities observed in solar wind and interplanetary magnetic field (IMF) observations at L1. Geoeffectivity is tested on Dst, am, PCN, and auroral indices responses.

The present work complements the Boochialini's study by analysing systematically all the 28 halo CMEs, including the seven halos CMEs not associated with SSCs. Source locations, potential L1 signatures and geoeffectivity of these seven halo CMEs provide an overview of the properties related to halo CMEs in 2002, complementing Boccialini's et al. results. None of the discontinuities possibly associated to each of the seven halo CMEs corresponds to a clear ICME signature, based on our observations and on existing catalogs, showing that the central regions of the halo CMEs are not passing L1.

From the L1 observations of frontside CME halos observed in 2002, we conclude that halo CMEs not associated with SSCs in 2002 are non-geoeffective. We also note that all halo CMEs observed in 2002 and associated with ICMEs or magnetic clouds at L1 are also associated with SSCs. lders. The work leading to this paper has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace (Radiation Belt Environmental Indicators for the Safety of Space Assets) project.
The Experiment Study on Debris Flow Formation Process Based on REE
Authors: Zhuang Jianqi
Published: March 2022

Designing the experiment on debris flow formation process at artificial rainfall at the conditions of the loose material unusually rich for studying the debris flow formation process. The main results showed: (1) the fine particles moving first for the initiation of debris flow, and then mixed with the large particle and runoff increased sharply, along with channel block-outburst phenomenon; the debris flow phenomena gradually disappeared with the fine particles migration off and the channel rough serious. (2) the slop failure and moving at the rainstorm, the failure material deposited in channel and formed the dams which effect the erosion and deposits of the channel with moving down to downstream. (3) the erosion sediment was main from middle and lower channel, then from the upstream and slope; the debris flow fan materials was main from the downstream channel, then from the upstream and slope. (4) the pore-water pressure and water content, which not only effected by rainfall, but also effected by fine particles content and soil structure, changed obviously and varied in different time and different sites with fluctuation. (5) the fine particles played an important role in the process of debris flow initiation and it’s accumulation and displacement effected the evolution of the basin topography and the formation of debris flow. In the debris flow forecast, the fine particles of soil content should be considered duo to its critical water content and pore-water pressure quite different in different content of fine particles of debris flow initiation.
Harmonisation of Opalinus Clay descriptions in Northern Switzerland: towards a uniform Subfacies Classification Scheme
Authors: Zimmerli Géraldine , Lauper Bruno , Deplazes Gaudenz , Jaeggi David , Wohlwend Stephan , Foubert Anneleen
Published: March 2022

The Opalinus Clay, an argillaceous to silty claystone formation, is known in Switzerland as being the selected host rock for deep geological disposal of high-, intermediate- and low-level radioactive waste. Since the 1990s, various properties of the Opalinus Clay have been studied within the framework of the Nagra (National Cooperative for the Disposal of Radioactive Waste) deep drilling campaigns and the Mont Terri Project (international research program dedicated to the investigation of claystone). The Opalinus Clay succession was deposited during the Late Toarcian to Early Aalenian in an epicontinental sea covering central Europe.

Although the Opalinus Clay is relatively homogeneous at formation-scale compared to other Mesozoic formations in northern Switzerland, significant lithological variations occur at lower scales. Besides m-scale lithofacies variations, high, intra-facies lithological variability occur at dm- to cm-scale. The facies diversity is primary attributed to regional differences in depositional, environmental and diagenetic conditions. In order to harmonize petrographic descriptions in an objective and quantitative way within all fields of research related to the Opalinus Clay, a subfacies classification scheme has been developed (SF1 to SF5, applied mostly on Mont Terri drill cores). The subfacies are distinguished by parameters such as texture (grain size, bedding, fabric and colour) and composition (nature and mineralogy of components). The five subfacies types can be further refined by additional attributes and sedimentary characteristics (biogenic, diagenetic, structural).

Subfacies descriptions are crucial to understand the lateral and vertical facies variability at regional scale. Moreover, accurate petrographic descriptions are a crucial prerequisite to many geotechnical studies and the prediction of petrophysical properties.

The main goal of the present study is to define a subfacies classification model covering the entire Opalinus Clay succession of the Mont Terri rock laboratory and successions deposited further to the east. Nagra is currently investigating three potential sites for radioactive waste storage within the Opalinus Clay in northern Switzerland. Nine new drill cores are used to apply the subfacies classification scheme. If necessary, the subfacies classification scheme will be adapted considering regional facies heterogeneities. Based on the new subfacies classification, depositional models for the Opalinus Clay will be refined.
Insights into NOx and HONO in the subtropical marine boundary layer during MarParCloud campaign at Cape Verde
Authors: Tilgner Andreas , Jiang Ying , Hoffmann Erik H. , Herrmann Hartmut
Published: March 2022

Chemical processing of reactive nitrogen species, especially NOx(=NO+NO2) and nitrous acid (HONO), determines/alters critically the photochemical ozone production in the troposphere, affecting the climate change, biological cycle and human healthy. However, the characteristics and sources of nitrous acid (HONO) and NOx in the remote marine atmosphere are still poorly understood. Herein, based on the data sets of HONO-related species as well as other parameters measured during MarParCloud campaign at Cape Verde in October 2017, the multiphase chemistry model SPACCIM equipped with the state-of-the-art multiphase chemistry mechanism CAPRAM was adopted with input of current literature parametrizations for various HONO sources in the tropospheric boundary layer (gas reaction of NO and OH, ocean-surface-mediated conversion of NO2 to HONO, NO2 reacted with organics on mineral dust, NH3 oxidation process, and dust-surface-photocatalytic conversions of reactive nitrogen species to HONO) to reveal the relative importance of each source for HONO in the remote boundary layer at Cape Verde. Each simulation was performed for 72 hours in different clusters obtained from the backward trajectories model analysis with HYSPLIT. The simulations well reproduced the observed HONO level and its diurnal pattern, and significantly improved the model performance for NOx and O3 in every cluster after 72 hours of operation, when considering the mechanisms of dust-surface-photocatalytic conversions of reactive nitrogen species. Furthermore, photolysis of the absorbed HNO3 on the dust is modelled to be the prevailing contributor for the daytime HONO at Cape Verde, which accounted for about 56%, following by the photo-enhanced of NO2 absorbed on the dust (41%). In contrast, the ocean-surface-mediated conversion of NO2 to HONO and other pathways were found unimportant for HONO formation at Cape Verde. For OH sources, HONO photolysis only accounted for a small proportion source (~3%) of the ambient OH level in remote marine boundary layer due to the low HONO concentration at Cape Verde. In summary, this study highlights the key role of dust aerosols in the formation of HONO and NOx at Cape Verde.