bluuebunny/crossref_metadata_2025 huggingface dataset:
Combined orbit and clock zero-difference solution at CODE: ambiguity resolution strategy
Authors: Calero Rodríguez Emilio José , Villiger Arturo , Schaer Stefan , Dach Rolf , Jäggi Adrian
Published: March 2022

The use of zero-difference processing schemes becomes more and more popular within the GNSS (Global Navigation Satellite Systems) community. This change from double- to zero-difference approaches increases the demand of PPP-AR (Ambiguity Resolution for Precise Point Positioning) enabling products. Those products can be created in two ways, either estimate the geometrical part (orbits) based on a double-difference global network solution with a separate zero-difference solution for the clocks and phase biases, or in a combined zero-difference solution. The latter one allows a more flexible approach; however, the challenge lies in the handling of the increased number of parameters and ambiguity resolution.

The estimation of combined orbit and clock zero-difference enabling products needs a thought-out design of the processing strategy, where the elimination and back-substitution steps are vital to deal with the large number of parameters. Nonetheless, the amount of ambiguity parameters dramatically grows with an increasing size of the network, posing some computational limitations, since they should not be eliminated for a successful ambiguity resolution. Such a restriction originates from fixing float orbits: their accuracy does not allow to estimate reliable ambiguity parameters. To cope with that, we propose a new algorithm capable to decouple them from the orbits, allowing to fix between-satellite ambiguities in a later station-wise parallelisation.

On the poster, we describe selected details on the ambiguity resolution strategy that we have developed. The obtained results are characterized and compared to other solutions using classical ambiguity resolution schemes.
Engineering geological mapping of near-surface rock mass quality of folded and thrusted arenaceous flysch units in the Northern Apennines (Italy)
Authors: Lombardi Gianni , D’Addario Enrico , Disperati Leonardo , Ferrarelli Francesco
Published: March 2022

The regionalized knowledge of the quality of near-surface rock masses is an important tool for land management/planning, as well as for guiding further in-depth studies aimed at landslide and earthquake risk assessment and civil engineering planning. The characterization of heterogeneous rock masses like flysch units represents a relevant challenge to engineering geologists due to the complex structure of these materials, which results from both their depositional context and tectonic history. Flysches are widespread all over the Apennines chain and their mechanical characterization is a difficult task given the occurrence of intercalation of layers with different lithology and strength. Moreover, the complexity of the thrust and fold tectonic framework makes the regional distribution of these characters difficult to predict. The aim of this work is to provide a method to map the near-surface rock masses quality for an arenaceous flysch widely cropping out in the outer Northern Apennines (Torrente Carigiola Formation, Aquitanian; Bettelli et al., 2002). This formation is mapped in both the geological map of the Regione Toscana (Italy) at the scale of 1:10,000 and the geological sheet “252 – Barberino di Mugello” (Bettelli et al., 2002) of the Italian Geological Map at the scale of 1:50,000 (CARG). It is made up by intercalated arenaceous (A) and pelitic (P) layers characterized by variable A/P ratio. The rock mass quality is evaluated by estimating, for a set of representative rock outcrops, the Rock Mass Quality Index (RQI; Disperati et al. 2016; Mammoliti et al. 2018). This index results from the analysis of both systematic Schmidt hammer rebound measurements (R) acquired at the nodes of a regular grid (ca. 20 R measurements for ca. 15-25 nodes) and the determination of the unit weight for representative outcrop rock samples. For the same outcrops, also the A/P ratio and bedding attitude are determined. The results show a positive linear correlation between RQI and the A/P ratio, confirming that the latter parameter is an important feature controlling the rock mass strength. This correlation is used to assess the distribution of both parameters within a set of geological cross sections traced normal to the regional structures trend (main thrusts and km-scale folds). Then, the structural features available from the literature geological maps allow us to extrapolate both the RQI and A/P ratio from the profiles to the map scale. Finally, a further set of the same rock outcrop data acquired after the above-described modelling procedure is used to check the accuracy of the method.
Stable carbon isotope data of enhanced dissolved methane in the East Siberian Arctic Shelf region
Authors: Brussee Marenka , Holmstrand Henry , Wild Birgit , Shcherbakova Ksenia , Kosmach Denis , Kurilenko Arkadiy , Shakhova Natalia , Semiletov Igor , Gustafsson Örjan
Published: March 2022

During the past two decades, extensive ebullition and elevated methane concentrations in both seawater and atmosphere have been observed in East Siberian Arctic Shelf (ESAS) region. The relative contribution of the potential sources to these enhanced methane concentrations and the related release processes are yet poorly understood. The sources of the observed methane could be recently microbially produced methane from organic material in Holocene sediments or thawing subsea permafrost, or preformed methane released from subsea permafrost, destabilizing methane hydrates or thermogenic gas reservoirs. We here use the 13C content of methane toward separating the contribution of thermogenic and microbial sources to methane-enriched bottom waters collected during four expeditions across the East Siberian Arctic Shelf (n = 181).

Our data suggest variability in methane sources between methane hotspots in three different regions of the ESAS, which are separated by large spatial scales (500-900 km). For the outer Laptev Sea, the average, 10th and 90th percentile δ13C values of near-bottom water methane were -44‰, -54‰ and -35‰, which suggests a dominant thermogenic source (expeditions in 2014, 2016, 2018 and 2020). For the inner Laptev Sea, the average, 10th and 90th percentile δ13C values of near-bottom water methane were -69‰, -77‰ and -58‰, which suggests a dominant microbial source (expeditions 2016, 2018, 2020). For the East Siberian Sea, samples of the years 2014, 2016 and 2020 have been analysed and the pattern is less consistent in time, where bottom water samples from 2014 are more enriched in 13C (δ13C average of -41‰) compared to the later years 2016 and 2020 (δ13C averages of -65‰ and -57‰). The differences between the three regions suggest that the dominant sources of the methane releases are different in these regions and likely reflect differences both in subsea compartments and processes forcing the current releases. 
Structural, mineralogical and petrophysical characterization of the hydrothermal system in Saint-Kitts Island (Lesser Antilles)
Authors: Favier Alexiane , Chibati Nadjib , Diraison Marc , Corsini Michel , Géraud Yves , Lardeaux Jean-Marc , Navelot Vivien
Published: March 2022

In Lesser Antilles arc several volcanic islands present high potential for the high enthalpy geothermal production. Saint-Kitts Island is one of them, where numerous surface evidences of active hydrothermal system such as fumaroles, boiling water are present. All of these activities are structurally controlled. Field analysis highlights four main families of faults or fractures with NE-SW, NW-SE, N-S, and E-W trends respectively.

The interaction of fluids (rain and sea waters) with host rock leads to meteoric and hydrothermal alterations of rocks according to depth of infiltration, usually consisting in their argillization. The characterization of these alterations allows a better understanding of the hydrothermal system of St Kitts and to estimate the geothermal potential of the resource in this island.

In the Frigate Bay area, in the southern part of the island, the rocks present an intensive structural and petrological transformations related to hydrothermal fluid flows. From study of mineralogical transformations with microscopic, SEM, EPMA, Raman and XRD analysis, we identify clays minerals (kaolinite, smectite), sulphates (jarosite, alunite, gypsum), quartz, opal, calcite and chlorite. These paragenesis are consistent with fluids above 100°C and allow to constrain the spatio-temporal activity of the hydrothermal system and the geothermal reservoir. Petrophysical properties, on a selected set of representative petro-structural facies, show large ranges of variation, porosity from 2 to 40%, permeability from 10-3 to 3 D; grain density between 2.84 and 2.31 g.cm-3, thermal conductivity is relatively low, 0.5 to 2 W.m-1.K-1. Samples alteration results in increasing of porosity and decrease in density. In turn the porosity increasing causes a decrease in the thermal conductivity.

These investigations allows us to interpret this site as part of a hydrothermal paleosystem and consider as an analogue of the deep northern part of the island under a current hydrothermal activity.
Monitoring Frost Heave and Thaw Settlement of Permafrost Using Timeseries InSAR Measurements
Authors: Jung Yoon Taek , Lee Yeji , Park Sang-Eun
Published: March 2022

Due to large temperature variations between the summer and winter seasons the active layer of permafrost undergoes repetitive thawing and freezing, and the increase of global temperature has accelerated permafrost degradation related to surface deformation seasonally and annually. Repeated freezing and thawing causes frost heave and thaw settlement, which results in displacement in the activity layer of permafrost. This surface displacement is also associated with ground ice and soil moisture content, and these factors in permafrost region could be observed through timely-dense SAR data. In particular, since the revisit time of Sentinel-1 (C-band) is relatively dense, timeseries SAR interferometry could be useful tools for monitoring and mapping subsurface soil properties over such a wide area. In this study, since the degree of freezing and thawing is very different spatially and temporally, we propose the method to indirectly estimate the ground ice content of the freezing period and the moisture content of the thawing period by quantifying the displacement using timeseries InSAR measurements in the Lena-river floodplain, Siberia.
Lithological control on erosional dynamics in a tectonically inactive mountain belt (Anti-Atlas, Morocco)
Authors: Clementucci Romano , Ballato Paolo , Siame Lionel , Faccenna Claudio , Yaaqoub Ahmed , Essaifi Abderrahim , Leanni Laëtitia , Guillou Valery
Published: March 2022

Topographic relief results from the complex interactions between tectonics and erosional surface processes. The efficiency of surface processes is a function of topographic slopes, bedrock erodibility and climatic conditions. Ancient orogens offers a favourable setting to isolate the contribution of lithology, as tectonically driven surface uplift is typically negligible and channel steepness is directly controlled by bedrock erodibility. The Anti-Atlas in NW Africa is a late Paleozoic orogen that contains a well-preserved, uplifted, relict landscape that has been slowly eroding since the late Cretaceous. Here, we combine geomorphic analysis with 10Be-derived denudation rates, to quantify the impact of bedrock erodibility and get insight into the surface evolution of the Anti-Atlas and the adjacent Siroua Massif. Specifically, we show that basin-wide denudation rates from the relict landscape range from 5 to 20 m/Myr, in agreement with the average long-term rates estimated from eroded volumes of Miocene volcanics and available thermochronometric data. This suggests that the regional relict topography has attained an erosional steady state and has been slowly decaying over geological time. Our results are comparable with data from other tectonically quiescent settings and demonstrate a positive linear correlation between denudation rates and normalized channel steepness indices. This allows constraining a narrow range of bedrock erodibility values for different rock-types (quartzite, granitic and sedimentary rocks), that are comparable with estimates from different stable settings. Finally, our compilation from tectonically inactive regions indicates that channel steepness, denudation rates and bedrock erodibility do not change significantly across different climatic zones and precipitation regimes highlighting the critical role of lithology in controlling the topographic relief.
On the cause of enhanced landward motion in adjacent segments of subduction zones after megathrust earthquakes
Authors: D'Acquisto Mario , Herman Matthew , Riva Riccardo , Govers Rob
Published: March 2022

Secular GNSS velocities on the overriding plate have been observed to change after several megathrust earthquakes (2003 Tokachi-oki, 2007 Bengkulu, 2010 Maule, 2011 Tohoku-oki, 2012 Oaxaca, 2014 Iquique). In particular, landward velocities are larger than before the earthquake in regions laterally adjacent to the ruptured zone, as close as 300–500 km along-trench from the centroid. Previous explanations of this enhanced landward motion invoked either increased slip deficit accumulation or overriding plate bending during postseismic relaxation; the mechanism is relevant for seismic hazard. We investigate whether plate bending alone – driven by afterslip and/or viscous relaxation – is likely to occur and can reproduce the observed patterns of velocity changes. We use 3D quasi-dynamic finite element models with periodic earthquakes.

We find that rapid afterslip in the shear zone downdip of the brittle megathrust, at depths greater than 40 km, produces only enhanced trenchward surface motion in the overriding plate. Bulk viscous relaxation in the mantle wedge does produce enhanced landward motion, although only when afterslip in the deep shear zone is spatially restricted by imposing a constant shear rate beyond a certain depth (75–150 km in our models). This landward motion indeed is a consequence of in-plane bending and shortening of the overriding plate. However, this modeled landward velocity change is one order of magnitude lower than observed, decays , and , resulting in no net enhanced landward motion. These findings are robust with respect to variations in mantle viscosity, plate elasticity, maximum afterslip depth and earthquake size. We thus conclude that plate bending probably occurs, but cannot explain the observed lateral landward velocity changes. The observed enhanced landward motion in the laterally adjacent regions of the subduction zone consequently reflect true local slip deficit accumulation at a faster rate than before the earthquake, whether because of transient slab acceleration or because of frictional changes on the megathrust. The implication is a greater seismic hazard in those lateral regions.
3.5-dimensional Simulation of Denitrification
Authors: Schulze Johannes Christian , Zawallich Jan Felix , Schlüter Steffen , Ippisch Olaf
Published: March 2022

Denitrification - a process known for over 200 years - is a microbiological process in which bacteria use nitrate(NO3−) for respiration in the absence of oxygen. Denitrification is a source of nitrous oxide(N2O), a greenhouse gas about 300 times as potent as CO2. It has been shown that denitrification occurs even in well aerated soils. The common assumption for this phenomenom is that denitrification occurs in short time frames localized in dense aggregates in the soil - at so-called hot moments in so-called hot spots.

Because of the differences in scale between hot spots and soil, it is currently numerically impossible to fully resolve large volumes of soil with hot spots when simulating denitrification due to contraints in computational power. This issue is tackled by developing a new 3.5-dimensional model.

It combines a three-dimensional model, that resolves the soil and simulates advection and diffusion of gas and water, with one-dimensional models for each hot spot within the simulated volume. Each hot spot is assumed to be spherical and by reducing it into one dimension the pore scale does not need to be resolved, thereby reducing the computational requirements. Within each hot spot the diffusion of gases in and out of the hot spot as well as microbiological reactions within them are simulated.

The resulting coupled system of partial differential equations is numerically solved using parallel computers. The computational efficiency of this approach is evaluated. The effect of important reaction parameters (e.g. Michaelis-Menten constants) is tested, compared and adapted to experimental data. 
Monitoring morphological changes in river deltas exploiting GEE and the full Landsat archive
Authors: Demertzi Isidora Isis , Detsikas Spyridon E. , Tselka Ioanna , Tzanavari Ioanna , Triantakonstantis Dimitris , Karymbalis Efthimios , Petropoulos George P.
Published: March 2022

River deltas are considered among the most diverse ecosystems with significant environmental and agricultural importance. These landscapes are vulnerable to any human activity or natural process that can disturb the fragile balance between water and land, thus causing morphological changes in the delta fronts. Earth observation (EO), with its capability to provide systematic, inter-temporal and cost-effective data provides a promising potential in monitoring the dynamic changes of river deltas. Recent advances in geoinformation technologies have allowed the development of cloud-based platforms for EO processing such as Google Earth Engine (GEE). It offers unique advantages such as rapid processing of a large amount of data in a cost and time-efficient manner. This study aims to assess the added value of GEE in monitoring the coastal surface area of river deltas based on the full Landsat archive (TM, ETM+, OLI, L9) and a machine learning (ML) technique. As a case study two river deltas, Axios & Aliakmonas, were selected located in northern Greece. Those are two of the largest rivers of the country, with Axios being also the second largest in the Balkans. Their joint river deltas create a fertile valley with great environmental and agricultural importance, which has also exhibited very strong dynamics in terms of its morphological characteristics over the last decades. In order to gain a better insight into the coastal dynamics of the studied region, Landsat multi-spectral data covering the period 1984 - present time was integrated into GEE and a Machine Learning (ML) classification approach was developed in the cloud-based environment. The two rivers delta dynamics were also mapped independently using photo interpretation serving as our reference dataset to map the river delta dynamics, in accordance to other studies. All the geospatial data analysis of the extracted morphological features of the river deltas was conducted in a geographical information system (GIS) environment. Our results evidenced the unique advantages of cloud platforms such as GEE, towards the operationalization of the investigated approaches for coastal morphological changes such as those found in the studied river deltas. Unique characteristics of the proposed herein methodology consist of the exploitation of the cloud-based platform GEE together with the advanced ML image processing algorithm and the full utilization of the Landsat images available today. The proposed approach also can be fully-automated and is transferable to other similar areas and can prove valuable help in understanding the spatiotemporal changes in coastal surface area over large areas.

KEYWORDS: Google Earth Engine, Landsat, Machine Learning, Earth Observation, river delta
Road surface friction measurement based on intelligent road sensor and machine learning approaches
Authors: Rasol Mezgeen , Schmidt Franziska , Ientile Silvia
Published: March 2022

Real prediction of friction coefficient on the road surface is essential in order to enhance the resilience of traffic management procedures for the safety of road users. Critical weather conditions could have a significant impact on the road surface, and decrease the reliable friction coefficient in extreme conditions. Weather parameters are involved in the process of traffic management are water film thickness, ice percentage, pavement temperature, ambient temperature, and freezing point. Smart road monitoring of the road surface friction changes over time means the real-time prediction of the friction coefficient changes in the future based on the intelligent weather road-based sensor is crucial to avoid uncontrolled conditions during extreme weather conditions. For this reason, the use of intelligent data analysis such as machine learning approaches is key in order to provide a holistic robust decision-making tool to support road operators or owners for further consideration of the traffic management procedures. In this study, a machine learning approach is applied to train 18 months of data collected from the real case study in Spain, and results show a good agreement between real friction coefficient and predicted friction coefficient. The trained model has been validated with various cross-validation approaches, and the high accuracy of the model is observed.

This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 769129 (PANOPTIS project).
Influence of chemo-mechanical processes and microstructural geometry on the mechanical behavior of geomaterials
Authors: Rattez Hadrien , Guével Alexandre , Lesueur Martin , Veveakis Manolis
Published: March 2022

The mechanical behavior of geomaterials depends primarily on their microstructure and in particular the geometry of their pores. This microstructure and its evolution in time due to deformation or chemical transformations also strongly affects the thermo-hydro-mechanical-chemical (THMC) processes in these porous materials. In the last decades, the development of micro-computed tomography has allowed to obtain accurate images of the rock-microstructures and how they evolve subjected to various factors. Many studies have used these 3D geometries of the porous space to characterize primary properties that depend on the microstructure, such as porosity, permeability or elastic moduli, by numerically solving field equations on µCT scan images of rock. For most projects of energy production or waste storage in geological media though, rocks eventually reach their limit of elasticity and the complementary plastic properties are needed to describe the full mechanical behaviour. In this contribution, we will show how we can assess the mechanical behavior of geomaterials in the long-term by solving nonlinear equations directly on realistic microstructures. First, we will discuss the necessary morphometric invariants that can be used in an upscaled constitutive law and show how we can predict the yield surface and its evolution with the chemical alteration of the rock from µCT scan images. Then, a phase field model that allows to simulate interface evolution is applied to investigate pressure solution creep at the grain scale and how it is influenced by microstructural geometry and catalyzing/inhibiting effects like temperature or clay content.
Unpacking spatial tensions: An interdisciplinary analysis of large-scale solar farm effects in drylands
Authors: Zhang Qian , Berntell Ellen , Lu Zhengyao , Zhang Qiong
Published: March 2022

The last decades have seen rapid growth of renewable energy globally for accommodating the urgent need of mitigating climate change. Large-scale projects like solar farms are actively financed by transnational investors to get established in drylands like Sahara. The Earth-system model simulations on large-scale solar-farm scenarios show an increased regional rainfall and vegetation cover, analogue to a “green Sahara” that happened in the past. It will not only induce local climate and ecosystem changes but also prompt remote impacts globally through atmospheric teleconnections and ocean dynamics. This suggests that spatial tensions are inherent to climate change mitigation measures, where action in one place at a particular time impacts not only this place and the short time but place at distance and time in the future. Meanwhile, case studies in social sciences seem to suggest common unintended social consequences of the ongoing projects but no systematic assessment across these projects has been done. This study thus aims to pilot an interdisciplinary investigation of the multi-dimensional effects of large-scale renewable energy projects, mainly solar farms in drylands. Our literature review of the social effects across solar farms and other major types of renewable energy projects shows that, local host communities widely bear adverse social consequences from these projects despite there are benefits at regional, national, and transnational levels. Economic redistribution and social differentiation rapidly occur through land acquisition, livelihoods, compensation, and development programs, further dividing local communities and amplifying inequalities. These social effects could be further complicated by the likely local climate and ecosystem changes as shown by our Earth-system model simulations. Based on this combined analysis, we conclude that spatial tensions in the current climate change mitigation measures challenge the assumption of global common goods and the reach of global justices. We urge interdisciplinary research to combine their different expertise for developing integrated conceptual and methodological models, for better understanding the intersected effects of renewable energy projects on drylands, and for advising fair and just climate mitigation policy and measures.
Deltaic mass-movement trigger analysis in Lake Hallwil (Switzerland)
Authors: Fabbri Stefano , Kremer Katrina
Published: March 2022

Subaquatic mass movements and their associated deposits are well known to serve as potential natural seismographs for paleoseismic event reconstruction in marine and lacustrine settings. However, the trigger of mass movements does not always have to be related to earthquakes solely, but can be also related to weather/climate (e.g. floods) or sediment overloading.

A crucial role in sedimentation processes can be attributed to the delta areas acting as transition zone between the subaerial and the subaquatic domain. In systems with high riverine sediment discharge, slope failures in deltas and turbidity currents can occur often. The sedimentary system of deltas is highly dynamic and their depositional regime is still poorly understood, in particular, when it comes to their role as mass-transport deposit provider. Apart from reported seismic and climatic triggers of such mass-transport deposits, also spontaneous aseismic trigger mechanisms have been reported for deltas as shown in several cases (e.g. 1687 AD Muota delta collapse in Lake Lucerne, 1996 AD Aare delta collapse in Lake Brienz, Switzerland).

New high-resolution multibeam swath bathymetric results of 10.3 km2 large Lake Hallwil (Central Switzerland) indicate that multiple subaquatic mass movement/debris flow events (hereafter termed only mass movements) occurred at the Dorfbach delta. At least 5 mass-movement deposits can be identified in the proximal area of the delta, indicative for repeated slope failures at the delta front.

A series of gravity short cores, forming a transect from the deepest basin towards the immediate forefront of the mass-movement deposits, were recovered in 2021 and scanned with a multi sensor core logger (MSCL) for mass-movement related turbidites and complemented by a sedimentological description of the cores. Samples for radiocarbon and 137Cs dating were taken for a detailed event chronology reconstruction of the partially laminated and varved sediment record.

Through the combination of morphological analyses from multibeam data and detailed core analyses, we will present first results of a mass-movment trigger analyses in Lake Hallwil, combining geochemical and geophysical investigation methods to build a mass-movement event chronlogy. Understanding this highly dynamic environment that sometimes produces catastrophic delta failures in equivalent larger settings, can help to improve natural hazard assessment and implementing safety measures for lake shores as well as coastal communities.
Crushed and fried: ductile rupture at depth due to grain size reduction and shear heating
Authors: Thielmann Marcel , Duretz Thibault
Published: March 2022

Since their discovery in 1928, deep earthquakes have been the subject of extensive research to unravel their nucleation and rupture mechanisms. Due to the elevated pressures and temperatures at depths below 50 km, brittle failure becomes less likely and ductile deformation is favored. To date, there is no consensus on the mechanisms resulting in deep earthquake generation. Three main mechanisms (dehydration embrittlement, transformational faulting and thermal runaway) have been proposed to cause deep earthquakes, but neither of them has been sufficiently quantified to yield a definite answer under which conditions they are active.

Here, we explore the feasibility of the thermal runaway hypothesis using 1D and 2D thermo-mechanical models. In particular, we investigate the impact of grain size reduction in conjunction with shear heating to see whether grain size reduction and shear heating are competitive mechanisms (which would prevent thermal runaway) or whether they are collaborative. Our results show that the combination of both mechanisms facilitates thermal runaway and significantly reduces the stress required for the occurrence of thermal runaway. We then investigate whether this combined failure mechanism may explain the seismicity observed in regions of detaching lithosphere, such as the Hindu Kush and the Vrancea earthquake nests. 
Modeling KHI Tube and Knot Dynamics and Their Impact on Mixing in the Lower Thermosphere
Authors: Mixa Tyler , Fritts David , Lund Thomas
Published: March 2022

Kelvin Helmholtz tube and knot (KH T/K) dynamics are a subclass of 3D shear instabilities that form when vortex "tubes" and "knots" connect adjacent, misaligned KH billows in a shear layer. While the existence of KH T/K was demonstrated in laboratory experiments by Thorpe 1987, they have only recently been observed in airglow images in the atmosphere (Hecht et al., 2021). Modeling studies by Fritts et al., 2021 determined that tubes and knots yield accelerated vorticity evolution and elevated dissipation rates in KH shear turbulence events, suggesting significant impacts to local mixing anywhere KH T/K dynamics occur. In this study, we present modeling results of T/K dynamics accompanying a thermospheric KH event captured by the 2018 Super Soaker campaign (Mesquita et al., 2020). Chemical tracers released by a rocketsonde on 26 January 2018 showed a coherent KH instability near 102 km that rapidly deteriorated within 45-90 s. Using wind and temperature data from the event, we conducted high resolution DNS employing both wide and narrow spanwise domains to facilitate (wide domain case) and prohibit (narrow domain case) the axial deformation of KH billows that allows tubes and knots to form. KH T/K dynamics are shown to produce accelerated instability evolution consistent with the observations, achieving peak dissipation rates 2.5 times larger and 2.4 buoyancy periods faster than in the case prohibiting T/K. The results suggest that enhanced mixing from thermospheric KH T/K events could account for the discrepancy between modeled and observed vertical eddy diffusion in the lower thermosphere (Liu 2021; Garcia et al., 2014) and merits further study.

 

References:

Fritts et al., 2021: https://doi.org/10.1029/2020JD033412 

Garcia et al., 2014: https://doi.org/10.1002/2013JD021208 

Hecht et al., 2021: https://doi.org/10.1029/2020JD033414 

Liu 2021: https://doi.org/10.1029/2020GL091474

Mesquita et al., 2020: https://doi.org/10.1029/2020JA027972 

Thorpe 1987: https://doi.org/10.1029/JC092iC05p05231 
Soil nutrient concentration with increasing elevational pattern in high altitude pastures in Leh Ladakh, India.
Authors: Ladon Padma
Published: March 2022

The extreme biophysical and climatic conditions in the trans-Himalayan region of Ladakh limits the plant growth and therefore since, time immemorial, high altitude pastures has been utilized for food and fodder security along with crop farming. The study investigated the changes in the concentration of organic carbon (C), nitrogen (N) and phosphorus (P), potassium (K) and ph in soil of high altitude pastures along the altitudinal gradient (4000 to 5500m amsl) in Leh Ladakh, India. Three sites were chosen for the study: Gya pasture (4500-5500 m), Shang pasture (4200-5000 m) and Igoo pasture (4000 to 4800 m). The results showed that concentration of soil organic carbon C and total nitrogen increased with increasing altitude in all the three sites. The concentration of available phosphorus P and available potassium K slightly decreased and had a non-linear relationship, however in case of Igoo pasture, the P and K value increased with increasing altitude. While the ph remained towards basic (ph= 7-8) irrespective of the site and elevational change. Besides the elevation, the practice of livestock grazing during summer migration could also impact the soil nutrient concentration as higher nitrogen and carbon content is observed near the temporary settlements of the herders in the sites where the practice was still intact.
Hydrothermal fluid system geological history and its influence on oil and gas rock complex, West Siberia, Russia.
Authors: Gafurova Dina , Yurchenko Anna , Khotylev Alexey , Karpova Evgeniya , Balushkina Natalia , Kalmykov Georgiy , Kalmykov Anton
Published: March 2022

Bazhenov formation is the richest and principal oil shale formation in Russia, which covers the majority of the West Siberian oil fields.

Reservoirs within upper part of Abalak and Bazhenov formations are often associated with secondary altered rocks. According to the results of lithological, mineralogical, isotopic studies of cores, hydrothermal reworking of the deposits took place in past, leading to the precipitation of specific mineral associations, changes in porosity and permeability, organic matter thermal alterations. Two main phases of hydrothermal activity can be distinguished. The first one – sedimentary, took place when the deposits were not consolidated - the analogue of modern methane seeps on the Sea floor. This phase is characterized by precipitation of authigenic carbonates, as well as precipitation of barite, framboidal pyrite. The second phase took place when the rocks were already consolidated – high-temperature deep fluids migrated from underneath strata along weak zones (faults), reached different levels within the Abalak-Bazhenov complex and reworked the rocks with change of its mineral composition, porosity and organic matter maturity. 

As a result of the various deep fluid systems impact two main mechanisms take place: a) formation of secondary reservoirs due to the leaching processes b) zones of secondary hydrothermal mineralization with signs of seal. The latter have an inhomogeneous and patchy character of distribution vertically and laterally. And when they are exposed to later aggressive fluids, their reservoir properties may be improved.

The objective of present research is to find integrated lithological, mineralogical, isotopic evidence of deep hydrothermal fluids influence on the rocks of Bazhen-Abalak complex and characterize development history of these processes. These studies allow to predict both prospecting intervals of oil and gas generation and secondary porous reservoirs for industrial exploration.
Energetic electron precipitations by chorus waves and its impact on the middleatmosphere
Authors: Miyoshi Yoshizumi , Saito Shinji , Hosokawa Keisuke , Asamura Kazushi , Oyama Shinichiro , Mitani Takefumi , Sakanoi Takeshi , Kero Antti , Turunen Esa , Verronen Pekka
Published: March 2022

Whistler chorus waves cause energetic electron precipitations into the Earth’s atmosphere, and signatures of precipitations are observed as diffuse,
pulsating aurora, and microbursts of energetic electrons. In this talk, we present our model that propagating chorus waves cause wide energy electron precipitations and relativistic electron microbursts are a high-energy tail of the pulsating aurora electrons. The chorus waves can resonate with tens keV electrons near the magnetic equator, which causes the pulsating aurora emissions, while the chorus waves can resonate with sub-relativistic/relativistic electrons at the off-equator, which cause the microbursts of energetic electrons. Moreover, we discuss that relativistic electrons cause a significant ozone destruction at the middle atmosphere by conjugate observations of Arase, ground-based observations, SIC ion chemistry simulation.
WMO Hydrological Research Strategy 2022‑2030: Operational Hydrology and Water Research Priorities
Authors: Ramos Maria-Helena , Cudennec Christophe , Cullmann Johannes , Dogulu Nilay , Luterbacher Jürg , Pechlivanidis Ilias , Salzberg Aaron
Published: March 2022

The World Meteorological Organization (WMO) supports the National Meteorological and Hydrological Services in their mission to deliver operational hydrology services for achieving water security and the water-dependent/water-related Sustainable Development Goals. Operational hydrology is defined as “the real time and regular measurement, collection, processing, archiving and distribution of hydrological, hydrometeorological and cryospheric data, and the generation of analyses, models, forecasts and warnings which inform water resources management and support water-related decisions, across a spectrum of temporal and spatial scales”. The WMO ‘Vision and Strategy for Hydrology and its associated Plan of Action*’, approved by the Extraordinary Congress in October 2021, identifies eight long-term ambitions for operational hydrology in support of the global water agenda: (1) No one is surprised by a flood, (2) Everyone is prepared for drought, (3) Hydro-climate and meteorological data support the food security agenda, (4) High-quality data supports science, (5) Science provides a sound basis for operational hydrology, (6) We have a thorough knowledge of the water resources of our world, (7) Sustainable development is supported by hydrological information, and (8) Water quality is known. The WMO initiatives aim at improving operational hydrology applications by communicating the needs and benefits of hydrological research in support of operational hydrology, and enabling new research partnerships and collaborations with academia and practice communities. In this presentation, we focus on science priorities and knowledge gaps necessary to improve the delivery and the use of hydrologic data, information, and services in operational hydrology. We discuss the WMO Hydrological Research Strategy and how we can strengthen Hydrology/Water topics under the umbrella of the WMO Research Board. We will also report on the main achievements of an expert team, brought together at the end of 2021 to identify complementary and new research areas to strengthen the linkages between water, weather, climate and environment within the existing WMO related programmes, including the Global Atmosphere Watch (GAW) Programme, the World Climate Research Programme (WCRP), and the World Weather Research Programme (WWRP).

* The process was led by the WMO Research Board (RB) with inputs from the WMO Hydrological Coordination Panel (HCP), the International Association of Hydrological Sciences (IAHS), and the Intergovernmental Hydrological Programme (UNESCO-IHP)
Changes in Intensity-Duration-Frequency Curves with an Ensemble of EA-CORDEX over South Korea
Authors: Yu Jae-Ung , Moon Jangwon , Kim Yunsung , Kwon Hyun-Han
Published: March 2022

An ensemble of ten regional climate model (RCM) simulations, forced by two global climate models (GCM) such as HadGEM2-AO, MPI-ESM-LR, and GFDL2M, at 25km spatial resolution from the CORDEX-EA Phase-2 is explored to assess the changes in rainfall intensity-duration-frequency (IDF), commonly employed in the hydrologic study, in a changing climate. This study first constructs a probability density function (PDF) for the observed precipitation. The log-likelihood for the modeled precipitation is then estimated from the PDF to rank the RCMs. Ensemble construction is further performed based on these rankings. The temporal downscaling approach employed in this study is based on a conditional copula function method developed by So et al. (2018), which incorporates a quantile mapping approach for bias correction. The proposed ensemble modeling framework for constructing future IDF relationships could provide a better representation of the uncertainty associated with climate models. A detailed discussion of the potential application of the ensemble approach in extreme analysis is further provided.
Modelling the transport of marine litter on Baltic sea ice and surface water
Authors: Lehtiranta Jonni , Kärnä Tuomas
Published: March 2022

The fate of plastic litter in seasonally ice-covered waters is an area of active research. The ice will transport any litter affixed to it, and the drift of sea ice differs substantially from the flow of surface currents, especially in marginal seas. This work studies typical drift patterns of marine litter in water, on ice, and in realistic circumstances where seasonal ice melts leaving marine litter suspended in flowing water.

The drift of litter in the Baltic Sea is simulated using the OpenDrift software package using oceanic drift from NEMO 4.0. A simple module was written to advect passive tracers that might be transported on sea ice or by sea water. The particles move with ice or surface water depending on the prevailing ice conditions. The results are analysed and compared to drift buoy results.
Optimizing the use of InSAR observations in data assimilation problems to estimate reservoir compaction
Authors: Kim Samantha S.R. , Vossepoel Femke C. , Wouters Marius C. , Govers Rob , Brouwer Wietske S. , Hanssen Ramon F.
Published: March 2022

Hydrocarbon production may cause subsidence as a result of the pressure reduction in the gas-producing layer and reservoir compaction. To analyze the process of subsidence and estimate reservoir parameters, we use a particle method to assimilate Interferometric synthetic-aperture radar (InSAR) observations of surface deformation with a conceptual model of reservoir. As example, we use an analytical model of the Groningen gas reservoir based on a geometry representing the compartmentalized structure of the subsurface at the reservoir depth.

The efficacy of the particle method becomes less when the degree of freedom is large compared to the ensemble size. This degree of freedom, in turn, varies because of spatial correlation in the observed field. The resolution of the InSAR data and the number of observations affect the performance of the particle method.

In this study, we quantify the information in a Sentinel-1 SAR dataset using the concept of Shannon entropy from information theory. We investigate how to best capture the level of detail in model resolved by the InSAR data while maximizing their information content for a data assimilation use. We show that incorrect representation of the existing correlations leads to weight collapse when the number of observation increases, unless the ensemble size growths. However, simulations of mutual information show that we could optimize data reduction by choosing an adequate mesh given the spatial correlation in the observed subsidence. Our approach provides a means to achieve a better information use from available InSAR data reducing weight collapse without additional computational cost.
Origin of the recent warming along the Angola Namibia coast
Authors: Tomety Folly Serge , Rouault Mathieu , Awo Founi Mesmin , Keenlyside Noel Sebastian
Published: March 2022

The Angola Benguela Front (ABF), is a very dynamic area, characterized by a high-temperature gradient of up to 4°C per degree latitude. It fluctuates in position and intensity seasonally which strongly affects the local marine ecosystem. A lot of research, in the past decades, has focused on the SST variability at the interannual timescale in the ABF and the Angolan and Northern Namibian coast to the north and south of it in the contest of Benguela Niños and Niñas. A warming trend since the 1980’s in that region has been reported in the literature and was attributed to a decreasing trend in wind speed. In this study, we look at the processes responsible for the warming in the ABF region. The OGCM NEMO model is used for that matter. The results suggest that the warming is due to various processes acting during different seasons. In autumn, the modelled SST warming trend occurs along the Angolan sector and it is associated with a positive trend in net surface heat flux (Qnet) and with the weakening of the vertical flow associated with the upwelling of cooler water to the surface. In early summer (November-January), the modelled SST warming trend occurs along the Angolan and Namibian sector and it is primarily associated with the intensification of a coastal poleward flow bringing more warm water from the tropics into the ABF region and with the weakening of vertical flow, while locally, Qnet trend generates a cooling trend. The modelled SST cooling trend that occurred south of the ABF, especially in winter and early spring, is primarily associated with a northwards trend in the horizontal subsurface current that advects cooler water from the south and an intensification of the upwelling of cold water to the surface.

 
Structurally controlled englacial origin of supraglacial debris cover and relief at a debris-covered Alpine glacier
Authors: Swift Darrel , Jones Andrew , Westoby Matthew , Bryant Robert , Veness Remy
Published: March 2022

It is common for temperate glaciers in mountainous regions to exhibit an extensive ablation-zone supraglacial debris cover. Although secondary reworking of surface debris and its role in modifying rates of glacier melt is receiving increasing attention, debris origin and primary distribution is poorly understood. Arguably, studies have tended to uncritically assume that debris supply is dominated by the passive transport of rockfall material that is dispersed within the ice (englacially) or is deposited onto the surface directly. We show that a substantial portion of the debris cover at Miage Glacier, Italy, can be attributed to release from medial moraine (MM) structures that can be observed englacially in debris-free ice cliffs and as supraglacial ‘melt out’ ridges containing vertically oriented clasts, occasionally supported by a fine matrix. Two MM types displaying contrasting debris characteristics were observed: one arising from the tributary confluences located near or below the equilibrium line position, and another derived from accumulation basin confluences. The former were reasonably continguous supraglacial features that in the upper- and mid-ablation area develop considerable relief that clearly acts as a primary control on debris redistribution across the glacier surface. The latter type are traceable for limited distances, and form more isolated areas of high topography in the mid-ablation area. We argue that ablation area debris cover and relief complexity in the upper- and mid-ablation area largely reflects debris entrainment at the point of medial moraine origin, though additional factors include the recent detachment of tributaries, the decline in mass contributed by specific accumulation basins, and the stochastic nature of headwall debris supply. Secondary debris redistribution processes appear to increase as glacier surface elevation declines, meaning in the lower ablation area surface relief decreases as debris distribution complexity increases.