bluuebunny/crossref_metadata_2025 huggingface dataset:
Detecting and assessing trends of CFCs and substitutes from IASI measurements
Authors: De Longueville Hélène , Clarisse Lieven , Franco Bruno , Whitburn Simon , Clerbaux Cathy , Camy-Peyret Claude , Coheur Pierre-François
Published: March 2021

The first Infrared Atmospheric Sounding Instrument (IASI) on the Metop satellites suite has achieved more than 13 years of continuous operation. The instrument stability and the consistency between the different instruments on the successive Metop (A, B and C) is remarkable and offer the potential to investigate trends in the concentration of various species better than with any other previous or current hyperspectral IR sounder. The low noise of IASI radiances is also such that even weakly absorbing species can be identified, on single or at least on averaged spectra. In this work we exploit the first decadal record of IASI measurements to (1) detect and monitor halogenated compounds regulated by the Montreal protocol (CFCs) or used as substitutes (HCFCs, HFCs), as well as fluorinated compounds (CF4, SF6) and potentially short lived chlorine species, for which substantial emissions are suspected (2) give a first assessment of the trend evolution of these species over the 2008-2017 period covered by IASI on Metop-A. This is done by targeting various geographical areas on the globe and examining the remote oceanic and continental source regions separately. The trend evolution in the different chemical species, either negative or positive, is validated against what is observed from ground-based measurement networks. We will conclude by assessing the usefulness of IASI and follow-on mission to contribute to global measurements of ozone depleting substances.
A feasibility study of a global risk pool scheme against tropical cyclones 
Authors: Ciullo Alessio , Strobl Eric , Martius Olivia , Bresch David N.
Published: March 2021

With increasing global economic damages due to weather-related events, insurance has even more become a valuable measure to share risks and increase resilience. Insurance solutions can be designed and implemented in various forms. Among these, cross-country insurance schemes emerged in the last years.

Natural catastrophe risk pools have the potential benefit of diversifying losses (thus lowering premiums) and of reducing administrative costs (as they are shared among countries). Currently, there are three catastrophe risk pools globally in place: the Caribbean Catastrophe Risk Insurance Facility (CCRIF), the African Risk Capacity (ARC), and the Pacific Catastrophe Risk Assessment and Financing Initiative (PCRAFI).

In the present work we aim to study the feasibility of establishing a global risk pool and, in particular, how countries might best be grouped together to achieve the greatest diversification. As a first step, this requires an assessment of global damages. We do this using the CLIMADA impact modeling platform and estimate worldwide damages from tropical cyclones. Then, we apply extreme value analysis and assess the diversification potential of various hypothetical pools based on measures from the systemic risk literature.
Reconstructing early Eocene (~55 Ma) paleogeographic boundary conditions for use in paleoclimate modelling
Authors: He Zhilin , Zhang Zhongshi , Guo Zhengtang
Published: March 2021

The early Eocene is a warm period with very high atmospheric CO2 levels, which receives many interests from climate modelling aspects. To simulate the early Eocene paleoclimate, a realistic reconstruction for land-sea distribution, paleotopography and paleobathymetry is the fundamental step. Here, we present global paleogeographic reconstructions for the early Eocene (~55 Ma), based on integrated paleogeographic data set, the Plate-tectonic reconstruction software (GPlates) and Geographic Information System software (ArcGIS). Comparing with previous paleogeographic reconstructions, we improve the reconstructions incorporated many latest geologic data and data set, including: (1) better representations of the Tethys Sea, some marginal or inland seas in the East and Southeast Asia, Atlantic and Arctic region, and the Drake Passage and Tasmanian Gateway; (2) integrated paleoelevation data of global high plateaus and mountains, especially the paleotopography of East Asia, and adopting the latest paleotopographic reconstruction data of the Antarctic; and (3) using the updated data set of oceanic crust paleo-age and oceanic sediment thickness to reconstruct the paleobathymetry.
Chemical characteristics of particulate matter - problem of Polish cities with air pollution
Authors: Furman Przemysław , Skiba Alicja , Samek Lucyna , Zimnoch Mirosław , Kistler Magdalena , Kasper-Giebl Anne , Gilardoni Stefania , Styszko Katarzyna
Published: March 2021

Recent years have brought a significant increase in public awareness of the issue of poor air quality in Poland. It is understandable that this problem has a direct impact on the quality of life of citizens of this country. Over the last few decades a concern over the health effects associated with air pollution was growing, mainly due to their carcinogenic and mutagenic properties. Various actions initiated by non-governmental organizations forced the authorities to undertake certain measures aimed at improving the quality of air in Poland, which, in the reports of the European Environment Agency is listed as one of the most polluted countries in the entire European Union. A model example here is the Krakow agglomeration. The city, located in a basin extending in the Vistula valley, surrounded on three sides by hills, in the cold period of the year struggles with the problem of poor air quality (very high concentrations of particulate matter and benzo(a)pyrene).

The objective of this research was better characterization of two major elements responsible for poor air quality in Krakow agglomeration: existing sources of pollution and  local meteorology during heating season (HS) and  non-heating season (NHS). Samples were collected with 24h resolution using Low-Vol samplers in Krakow (50°00'38.1"N 19°56'57.1"E, Kurdwanow, Malopolska, South Poland) from February 2014 to January 2015. Based on the results of polycyclic aromatic hydrocarbons, cations, anions, mercury, organic and elemental carbon analyzes of samples of particulate matter collected in the city’s atmosphere, sources have been identified and classified them from the most to the least significant ones. The modeling tool Hybrid Single-Particle Lagrangian Integrated Trajectory model (HYSPLIT), developed by NOAA’s Air Resources Laboratory, was used to investigate the possible trajectories of air pollutants.

This research was partially financed by the AGH UST grant 16.16.210.476 subsidy of the Ministry of Science and Higher Education. PF and AS have been partly supported by the EU Project POWR.03.02.00-00-I004/16. The infrastructure of the AGH Center of Energy in Kraków was applied in order to determine the concentration of ions.
3D geological modelling of the South Orkney Microcontinent (southern Scotia Arc, Antarctica) from seismic and potential field data
Authors: Morales-Ocaña Cecilia , Bohoyo Fernando , Escutia Carlota , Marín-Lechado Carlos , Druet María , Rey-Moral Carmen , Galindo-Zaldívar Jesús
Published: March 2021

The South Orkney Microcontinent (SOM) is located in the central sector of the South Scotia Arc, at the Weddell Sea northern edge. The SOM is the largest continental block in the southern Scotia Arc with a surface of more than 70.000 km2. Its current location is the result of the continental break-up from the Antarctic Peninsula related to the Powell Basin opening, considered one of the first steps in the formation of the Drake Passage during the Eocene-Oligocene.

In this work we present a 3D geological model of the SOM built with Geomodeller® using free-air gravity anomaly data from Topex and magnetic data from WDMAM. To obtain a reliable result, some constrains have been taken into account: (1) GEBCO data are used to establish the bathymetric level, (2) basement depth and geometry is calculated from multi-channel seismic profiles over the study area obtained from the Seismic Data Library System (SDLS), and (3) the analytic signal of total field magnetic anomalies has been used to limit the extension of the bodies that cause the PMA (Pacific Margin Anomaly).

All these data, together with additional geological and geophysical interpretation, have allowed to build the 3D model. The characterization of the sedimentary basins shape, the deep crust structure and Moho geometry, the volume of the magnetic bodies and the nature and geometry of the SOM margins will provide a better understanding of the complex SOM structure resulting from different tectonic phases since the Mesozoic and related to the Scotia-Drake opening.

The preliminary result shows a good fit between the observed and calculated gravimetric anomaly. We are currently working on the gravimetric inversion to obtain an optimal adjustment.
A novel in-situ soil enzymatic activity sensor- expanding soil precision measurements to indicator of soil health.
Authors: Iven Hélène , Meller Sonia , Luster Jörg , Frossard Emmanuel
Published: March 2021

Soil enzymes catalyse the hydrolysis of various soil compounds leading to an increase in the availability of nutrients for plants and microorganisms, but the increase in mobility might also lead to losses by leaching. Sources of extracellular soil enzymes in soil include release by soil microorganisms such as bacteria and fungi and plant roots but also microbial necromass. Irrespective of their source, the released enzymes can accumulate in the soil by becoming stabilized on mineral and organic surfaces. It is generally assumed that 40 to 60% of measured enzyme activity originate from stabilized enzymes. As such they directly affect the ability of a soil to fulfil its numerous functions, including the provision of nutrients to plants, the cleaning of percolating water and climate regulation.

Although measurements of soil enzyme activity are increasingly recognised as sensitive indicators of soil health, variations and inconsistencies between existing methods make it difficult to compare the results of different studies. Most commonly, soil enzyme activities are assessed using destructive biochemical laboratory incubations, thus altering the natural soil conditions.

Therefore, based on the principle of soil zymography, a membrane based method to map the heterogeneity of enzymatic activity on exposed soil surfaces, we developed a portative, hand-held sensor allowing rapid measurement of the soil enzymatic activity in-situ (Digit Soil; https://www.digit-soil.com/). In this presentation, we will compare the performance of our sensor to laboratory incubations for the application on various types of soils differing in basic properties such as pH, texture and soil organic matter content at different moisture conditions.

Based on the results, we will discuss the prospects this new sensor offers for rapid in-situ evaluation of soil health in the framework of precision agriculture and sustainability labels.
Brittle deformation effects on the geothermal area framework, in Southern Tuscany, by multiscale lineament domain analysis
Authors: Rabuffi Federico , Musacchio Massimo , Salvini Francesco , Silvestri Malvina , Buongiorno Maria Fabrizia
Published: March 2021

Remote Sensing is a proven tool to study the Earth's surface and allows to analyze the wide portion of the surfaces by using different platforms/sensors (e.g. optical and active remote sensing, lidar), giving the possibility of multidisciplinary and multiscale approaches. In the proposed study, remote sensing analysis provides the possibility to understand the relationship between tectonic structures, lithology, and geothermal manifestations, and to test these techniques to monitor geothermal areas. This study allowed us to better understand the structural framework of a geothermal area, located in Southern Tuscany, highlighting the role of brittle deformation to produce an enhanced pathway for fluid migrations and upwelling.

The studied area is the “Parco Naturalistico delle Biancane” (PNB) in the Grosseto province and belongs to the Cenozoic Tyrrhenian-Apennine orogenic system. The tectonic framework includes a fault and thrust belt setting derived from the collision between the Corsica-Sardinia Block and Adriatic Plate during late Oligocene-Miocene times. This process determined the pile-up of several tectonic units which are, from the top: (1) Ligurian Units consisting of ophiolitic rocks and pelagic sediments (Jurassic - Oligocen); (2) Cretaceous-Oligocene terrigenous deposits; (3) The Mesozoic Tuscan Nappe. Successively, the belt was affected by a regional, mainly extensional tectonics, then a magmatic intrusion affected this thinned Tyrrhenian belt to form the Tuscan Magmatic Province. In Recent time, the region underwent a general, yet differentiated uplift, and the major geothermal areas locate to the relative higher zone. This provides the Southern Tuscany to be the main Italian geothermal area.

In this study, we analyzed the area from several points of view. The lineament domain analysis was performed in a multiscale approach: from 90 meters to 5 meters of pixel size, including 30 m and 10 m. This multiscale analysis allowed the identification of a number of lineament clusters related to the different tectonic phases which affected the PNB area. The found lineament distribution (in terms of azimuth and length) reflects the geodynamics effects on the surface, their clustering was related to the various crustal stress trajectories both at the regional and local scales.
In solution stability of organic peroxides
Authors: Baeza-Romero María Teresa , Antiñolo María , Espildora Eva María , Lopez-Arza Moreno Vicente , Valero Edelmira
Published: March 2021

Organic peroxides are compounds possessing one or more oxygen–oxygen bonds. They are derivatives of hydrogen peroxide (H2O2), in which one or both hydrogens are replaced by a group containing carbon. This kind of compounds are ubiquitous in the environment being detected in Secondary Organic Aerosols (SOA)1,2, rainwater, and cloud water3,4. The role of peroxides is very important from health and climate perspectives5, and to understand the mechanism of SOA formation6. It is known that they can easily decompose to form H2O2 and other products7. However, the decomposition processes for organic peroxides have not been studied in a systematic way that allow to stablish improved strategies for sampling and storage of the samples. Moreover, these processes would happen in the atmosphere and need to be included in atmospheric models.

The aim of this work is to study the decomposition rate at different temperatures of hydroperoxides formed in the aqueous solution of some atmospherically relevant organic compounds with ozone. Iodometric method is used to monitor the total peroxides concentration. The implications related to sampling and storage for atmospheric samples containing organic peroxides are discussed together with the atmospheric impact of the studied processes.      

REFERENCES:    1. Mutzel, A., L. Poulain, T. Berndt, Y. Iinuma, M. Rodigast, O. Böge, S. Richters, G. Spindler, M. Sipila, T. Jokinen, et al. 2015. Environ. Sci. Technol. 2015, 49 (13):7754–61. ; 2. Kristensen, K., Å. K. Watne, J. Hammes, A. Lutz, T. Petäjä, M. Hallquist, M. Bilde, and M. Glasius. Environ. Sci. Technol. Lett. 2016, 3 (8):280–5; 3. Kelly, T.J., Daum, P.H. and S.E. Schwartz. J. Geophysical Research. 1985, 90(D5), 7861-7871; 4. Huang, S., Fuse, Y., Yamda, E. and Kagaku, B. Bunseki Kagaku. 2004, 53(9), 875-881; 5. Tao, F.; Gonzalez-Flecha, B.; Kobzik, L. Free Radical Biol. Med. 2003, 35, 327−340; 6.Seinfeld, J. H.; Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change, 3rd ed.; John Wiley & Sons: Hoboken, NJ, 2016; 7. Badali, K.M., Zhou, S., Aljawhary, D., Antiñolo, M., Chen, W.J., Lok, A., Mungall, Wong, E., J. P. S., Zhao, R. and Abbatt, J.P.D. Atmos. Chem. Phys., 2015, 15, 7831–7840.
sensitivity of middle atmospheric ozone to solar proton events: comparison between climate model and satellites
Authors: Nilsen Kenneth , Kero Antti , Verronen Pekka , Szelag Monika , Kalakoski Niilo , Jia Jia
Published: March 2021

Energetic particle precipitation (EPP) impact on the middle atmospheric ozone chemistry plays potentially an important role in the connection between space weather and Earth's climate system. A variant of the Whole Atmosphere Community Climate Model (WACCM-D) implements a detailed set of ionospheric D-region chemistry instead of a simple parameterization used in the earlier WACCM versions, allowing to capture the impact of EPP in more detail, thus improving the model for long-term climate studies. Here, we verify experimentally the ion chemistry of the WACCM-D by analysing the middle atmospheric ozone response to the EPP forcing during well-known solar proton events (SPEs). We use a multi-satellite approach to derive the middle atmospheric sensitivity for the SPE forcing as a statistical relation between the solar proton flux and the consequent ozone change. An identical sensitivity analysis is carried out for the WACCM-D model results, enabling one-to-one comparison with the results derived from the satellite observations. Our results show a good agreement in the sensitivity between satellites and the WACCM-D for nighttime conditions. For daytime conditions, we find a good agreement for the satellite data sets that include the largest SPEs (max proton flux >10^4  pfu). However, for those satellite data-sets with only minor and moderate SPEs, WACCM-D tends to underestimate the sensitivity in daytime conditions. In summary, the comparisons WACCM-D ion chemistry, combined with the transportation, demonstrates a realistic representation of the SPE sensitivity of ozone, and thus provides a conservative platform for long-term EPP impact studies.
Isotopic Characterization of groundwater in semi-arid Western India: Insights into Hydrogeological Processes
Authors: Pandey Amit , Padhya Virendra , Deshpande Rajendrakumar Dattatraya
Published: March 2021

The study area located in the semi-arid western India is the tenth most populous Indian state with an estimated population of 60.3 million (~5% of Indian population) and population density of 308 persons/km2. About 42.6% of the population lives in the urban area and 57.4% in rural areas. Surface water paucity, seasonal availability and a varying amount of rainfall in this region make groundwater an important and most preferred source to fulfil the demand for drinking water, agricultural, industrial and sustain an important native terrestrial ecosystem. The over-dependency on groundwater leads to various problems related to quality and quantity of groundwater like a rapid decline of the water table, mining of static groundwater, seawater intrusion and groundwater contamination by geogenic and anthropogenic sources. Sustainable water management across the state must be underpinned by the clear understanding of groundwater recharge characteristics, relationship between recharge sources and groundwater, factors controlling the interaction between surface water and groundwater, deletion of the areas not receiving a freshwater influx. Shallow groundwater samples were collected during IWIN nation programme (2008 to 2013)  for the year 2009 to measure the stable isotopes of oxygen and hydrogen in groundwater from 205 locations during post-monsoon (November ) season and 207 locations in pre-monsoon season ( May-June) to understand the factors governing Spatio-temporal variation in isotopic composition and obtain insights about the spatially variable recharge characteristics and possible controlling factors. The oxygen and hydrogen isotopic values and their spatio-temporal variations in the study area demonstrate that (1) d18O depletion in post-monsoon GW compare to pre-monsoon infer the seasonal recharge of GW (2) d18O of post-monsoon GW ( -2.3‰) lie in between the d18O of pre-monsoon GW ( -1.9‰) and d18O of southwest monsoon rainfall (-4.1‰) indicates post-monsoon GW is the mixture of these two components (3) Seasonal variation in d18O deduce that 56% ( ~109773 km2) of the total land area (~ 196773 km2) shows seasonal GW recharge while 32% (62727 km2) is not receiving any freshwater influx (4) 36% of post-monsoon samples while 40% of the pre-monsoon samples have negative d-excess values and shows a decreasing trend with d18O infer evaporation of sub-surface water prior to recharge (5) Alluvial aquifer of north Gujarat has depleted d18O compare to adjacent high elevated hard rock aquifer indicates irrigation return flow of deep static water.
Advances and benefits of fractal models to predict streaming potentials in partially saturated porous media
Authors: Jougnot Damien , Thanh Luong Duy , Soldi Mariangeles , Vinogradov Jan , Guarracino Luis
Published: March 2021

Understanding streaming potential generation in porous media is of high interest for hydrological and reservoir studies as it allows to relate water fluxes to measurable electrical potential distributions in subsurface geological settings. The evolution of streaming potential stems from electrokinetic coupling between water and electrical fluxes due to the presence of an electrical double layer at the interface between the mineral and the pore water. Two different approaches can be used to model and interpret the generation of the streaming potential in porous media: the classical coupling coefficient approach based on the Helmholtz-Smoluchowski equation, and the effective excess charge density. Recent studies based on both approaches use a mathematical up-scaling procedure that employs the so-called fractal theory. In these studies, the porous medium is represented by a bundle of tortuous capillaries characterized by a fractal capillary-size distribution law. The electrokinetic coupling between the fluid flow and electric current is obtained by averaging the processes that take place in a single capillary. In most cases, closed-form expressions for the electrokinetic parameters are obtained in terms of macroscopic hydraulic variables like permeability, saturation and porosity. In this presentation we propose a review of the existing fractal distribution models that predict the streaming potential in porous media and discuss their benefits compared against other published models.
Impact of the atmospheric-hydrological fully coupled approach in a high-resolution medium-range forecasts: a case study in the Mediterranean
Authors: Furnari Luca , Magnusson Linus , Mendicino Giuseppe , Senatore Alfonso
Published: March 2021

Mediterranean coastal areas are prone to hydrometeorological extremes. Their complex orography often enhances the severity of high impact events and, at the same time, makes forecasts more challenging, particularly in the medium range. Nevertheless, global operational forecasts significantly improved their accuracy in the last decades, while several novelties in mesoscale modelling are emerging, such as the atmospheric-hydrological fully coupled approach, which explicitly describes the complex interactions between the Planetary Boundary Layer (PBL) and land surface including terrestrial lateral water transport. Overall, several clues open new perspectives to define new standards in medium-range forecast performances in the Mediterranean basin.

This study investigates the skills of the Advanced Research WRF (ARW) mesoscale model both one-way and two-way coupled with the hydrological extension WRF-Hydro in providing a medium-range (7 days) forecast of a severe event hitting the Calabrian peninsula (southern Italy) in November 2019. Such event was simulated in a classical ensemble approach, using the European Center for Medium-Range Weather Forecasting (ECMWF) ensemble product (Ensemble Prediction System – EPS), which consists of 50 members providing the initial and boundary conditions to the mesoscale model. WRF model was applied in two one-way nested domains with 10 km and 2 km horizontal resolutions, encompassing most of the Mediterranean basin. WRF-Hydro was applied in the innermost domain, with NOAH-MP as Land Surface Model. Surface and subsurface routing was performed adopting 200 m as horizontal resolution.

Results highlighted that the fully coupled approach increased soil moisture and latent heat flux from land in an increasing way in the days preceding the event. Such an increase partially affected the lower PBL layers. However, when shoreward moisture transport from surrounding sea rapidly increased becoming the dominant process, only a weak signature of moisture contribution from land to the atmosphere could be detected, resulting in only slightly higher precipitation forecast and slightly increased hydrological response. Overall, the proof-of-concept carried out in this study highlighted a remarkable performance of the medium-range ensemble forecasts, suggesting a profitable use of the fully coupled approach in the selected study area for forecasting purposes in circumstances in which soil moisture dynamics and exchanges with the atmosphere are of particular interest.
Micro-climatological influences on temperature condition in an old people’s home in Helsinki, Finland, caused by extended heat-waves 
Authors: Drebs Achim , Sinsel Tim , Jylhä Kirsti
Published: March 2021

In our research we describe the micro-climatological influences of two heat-waves around and the air temperature development in a certain old people’s home in Helsinki, Finland. The stand-alone six-storey concrete building was erected in the late 1970’s and represents the prevailing construction type of this area. The building is located on a slightly southwards declining slope.

The first simulation used real meteorological forcing-data from the heat-wave event in summer 2018, which lasted from July, 13th until August, 5th. In this period the daily maximum air temperature reached almost every day 25 °C and more, sometimes even more than 30 °C. All air temperature, wind, humidity, and solar radiation (cloudiness) measurements were conducted at a near-by synoptical weather station.

The second simulation used fourteen-day constructed meteorological forcing-data, based on a clear-sky, slowly increasing air temperature, higher than normal humidity, and low wind conditions assumption starting on July, 13th (day 194 of the year).

We used the holistic ENVI-met simulation soft-ware to simulate the physical environment around the old people’s home and especially the energy fluxes inside the concrete walls to explain the needs for cooling demands.

The research is part of the HEATCLIM-project financed by the Academy of Finland Science Program CLIHE (2020-2023).
Operational Water Service for Copernicus Climate Change Service: development at European scale
Authors: Photiadou Christiana , Berg Peter , Bozhinova Denica , Eronn Anna , Ludwig Fulco , del Pozo Garcia Maria del Pozo Garcia , Pechlivanidis Ilias
Published: March 2021

The Operational Water Service of C3S (developed by the Swedish Meteorological and Hydrological Institute (SMHI)) aims to help a broad range of water managers with water allocation, flood management, ecological status and industrial water use, to adapt their strategies in order to adapt to climate variability and change. The aim is to speed up the workflow in climate-change adaptation by using seasonal hydrological forecasts and climate-impact indicators. This is done by offering an interactive web application with refined data, guidance and practical showcases to water managers across Europe. Policy makers will find a comprehensive overview for Europe with key messages and consultants can use the service for developing climate impact assessments and adaptation strategies.

The development of the current operational climate service for water management is based on the experience from two previous proof-of-concepts and will also be aligned with the hydrological model system of the Copernicus Emergency Management Service (CEMS).  The service is uses data from the Climate Data Store and the operational hydrological seasonal forecasting system runs entirely in the European Centre for Medium range Weather Forecasts (ECMWF) technical environment, although developed by SMHI.

The operational Water Service of C3S will be launched during the spring of 2021, and a series of activities and user interactions will be organised to ensure that the applications developed for the service fulfil the users’ needs. Here, we present the development process of the operational service and key outcomes from co-design interactions and resulting applications. The key issues identified by the user community were: i) clear visualisation and graphical representation of skill in seasonal forecasts and confidence in climate projections, ii) need of detailed documentation and process transparency in hydrological models and production of data, iii) user guidance and tutorials are needed for better understanding of the applications, and iv) workflows and scripts for indicator production in new applications for developers of information systems.
Kinematics, non-coaxial flow and rheological constraints of the South Tibetan Detachment System in central Himalaya
Authors: Laura Nania , Chiara Montomoli , Salvatore Iaccarino , Bernd Leiss , Rodolfo Carosi
Published: March 2021

A challenge in tectonic studies concerns the attempt to relate deformation features at the microscale and the crystalline lattice scale of rock-forming minerals up to the regional scale. The South Tibetan Detachment System (STDS) in Himalaya is a natural laboratory for such correlations, being a prime example of regional-scale low-angle ductile extensional fault/shear zone systems within collisional settings, with a top-down-to-the-north sense of shear. The STDS shearing involves, with a thickness of c. 1-2 km, the uppermost part of the metamorphic core of the belt, the Greater Himalayan Sequence (GHS), and the basal part of the Tethyan Himalayan Sequence (THS), developing a mylonitic foliation and a nearly constant strike. Recurrent ideas on the STDS architecture and rheological behavior come from the clearly and well exposed 3D outcrops around the Everest area (Eastern Nepal), where it mostly developed in quartz-bearing lithologies with a lower ductile shear zone and an upper brittle fault. Vice versa, the location of the exact shear zone boundaries and structural evolution of the STDS are still under controversial discussions in Central-Western Nepal, where few kinematic indicators occur in the carbonate-bearing lithologies of both GHS and THS.

In this contribution, we examine a suite of over 20 field-oriented marble samples affected by the STDS, comparing the deformation recorded by calcite in two different areas in central Himalaya, where essentially only the ductile shear zone has been clearly identified. Calcite microstructures (e.g., grain size and shape) and crystallographic preferred orientations (textures) of impure marbles from the Lower Dolpo region and pure marbles from the Manaslu area (Western Nepal), coupled with petrographic observations, allowed us to conclude on temperature, paleo stress, strain rates, and kinematic of the flow. Our results support the idea of a complex history of the STDS in regard to different thermal and lithospheric stress regimes during deformation. Decreasing temperatures from an early-stage of shearing (at HT-MT condition) to a late-stage of shearing (LT conditions) are coupled with increasing differential stress recorded at comparable strain rates and decreasing simple shear conditions. We propose a progressive exhumation of the STDS towards shallower structural levels, with a temporal (rather than spatial) lowering of kinematic vorticity (“decelerating strain path”), in which progressively more general shear replaced high-temperature simple shear flow during cooling, strain hardening, and narrowing of the shear zone. Microstructural and texture analysis of pure and impure marble proved to be a useful approach to characterize the STDS location and architecture, supporting that, when the upper-brittle fault is not well developed, the ductile shearing proceeded at high structural levels.
Scaling properties of the Mw7.0 Samos (Greece), 2020 aftershock sequence.
Authors: Vallianatos Filippos , Pavlou Kyriaki
Published: March 2021

On October 30, 2020 a strong shallow earthquake of magnitude Mw=7.0 occurred on the Eastern edge of Aegean Sea. The epicenter was located on the North offshore of the Greek island of Samos. The aim of our work is to present a first analysis of the scaling properties observed in the aftershock sequence as reported until December 31, 2020, as numerous seismic clusters activated. Our analysis is focused on the main of the clusters observed in the East area of the activated fault zone and strongly related with the main shock’s fault. The aftershock sequence follows the Omori law with a value of p≈1.01 for the main cluster which is remarkably close to a logarithmic evolution. The analysis of interevent times distribution, based on non-extensive statistical physics indicates a system in an anomalous equilibrium with a cross over from anomalous (q>1) to normal (q=1) statistical mechanics, for great interevent times. A discussion of the cross over observed, in terms of superstatistics is given. In addition the obtained value q≈1.67 suggests a system with one degree of freedom. Furthermore, an scaling of the migration of aftershock zone as a function of the logarithm of time is discussed in terms of rate strengthening rheology that govern the evolution of afterslip process.

References

Tsallis, C. Introduction to Nonextensive Statistical Mechanics-Approaching a Complex World; Springer: New York, USA, 2009; pp. 1–382.

Perfettini, H.,Frank, W. B., Marsan, D., and Bouchon, M. (2018). A model of aftershock migration driven by afterslip. Geophys. Res. Let., 45, 2283–2293.

Vallianatos, F.; Papadakis, G.; Michas, G. (2016). Generalized statistical mechanics approaches to earthquakes and tectonics. Proc. R. Soc. A Math. Phys. Eng. Sci. 2016,472, 20160497

Acknowledgements

We acknowledge support of this work by the project “HELPOS – Hellenic System for Lithosphere Monitoring” (MIS 5002697) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).
Learning Principles in the Biochemistry of Plant Silica Precipitation 
Authors: Ayieko Vincent , Elbaum Rivka
Published: March 2021

Plants produce silica in large quantities, up to 2-10% per dry weight, depending on growth conditions and plant species. The roots absorb monosilicic acid from the soil, and it is transported with water and distributed in nearly all plant tissues. With evapotranspiration, the silicic acid solution is concentrated, and eventually silica forms at leaf epidermis. Nonetheless, the distribution of silica deposits is not uniform within plant tissues. This suggests that there are biological processes that control the deposition of the mineral. In a recent work, the protein Siliplant1 (Slp1) was discovered to precipitate silica in plants. Slp1 is expressed in sorghum leaf epidermal cells called silica cells. Biological molecules active in silica formation typically present positive charge moieties and form some 3D aggregation pattern that allows monosilicic acid to condense into bigger organized structures. Slp1 contains a 24 amino acid N-terminal signal peptide, followed by 124 amino acid linking sequence and a 7-repeat sequence. Slp1 without the signal peptide and a short, conserved peptide appearing five times in Slp1 precipitate silica in vitro. However, the activity of other parts of Slp1 in silica precipitation remains unknown. To analyze sequence motifs that precipitate silica, we synthesized segments of the repeating sequence in Slp1, and characterized the precipitation reactions by yield and spectroscopy. Thermal gravimetric and electron microscopy analyses are planned. Preliminary results show that the most conserved region in the repeating sequence precipitates silica at a concentration range of 1-1.5 mg/mL in a 100 mM silicic acid solution. Under buffered conditions, this peptide is positively charged, precipitating silica at pH between 6 and 7. In contrast, silica-gel formed at pH 8 or 5 after overnight incubation. In comparison, the full length Slp1 (missing the signal peptide) precipitates silica at an estimated concentration of 2.9 mg/mL and pH 6-8. Peptides flanking the conserved sequence did not precipitate silica. Precipitation reactions with combinations of peptides precipitated silica only when the conserved peptide was mixed with the peptide following it at a 1:1 ratio. This part of Slp1 presents –OH moieties that may interact with silica. The reaction produced silica gel as well as silica. When the conserved region was mixed with a preceding peptide, only silica-gel formed. This region presents acidic groups that may block the positive charge on the conserved region. We conclude that the conserved peptide is the only part of the Slp1 repeating region that actively precipitates silica. The peptides flanking the conserved region are not directly involved in silica precipitation.  However, they may allow silica precipitation at increased pH, as seen in the full length Slp1. Further investigation is planned to understand their roles in silica formation.
Conditions needed for generation of type II radio emission in the interplanetary space
Authors: Jebaraj Immanuel Christopher , Kouloumvakos Athanasios , Magdalenic Jasmina , Rouillard Alexis , Krupar Vratislav , Poedts Stefaan
Published: March 2021

Eruptive events such as Coronal mass ejections (CMEs) and flares cangenerate shock waves. Tracking shock waves and predicting their arrival at Earth is a subject of numerous space weather studies. Ground-based radio observations allow us to locate shock waves in the low corona while space-based radio observations provide us opportunity to track shock waves in the inner heliosphere. We present a case study of CME/flare event, associated shock wave and its radio signature, i.e. type II radio burst.

In order to analyze the shock wave parameters, we employed a robust paradigm. We reconstructed the shock wave in 3D using multi-viewpoint observations and modelled the evolution of its parameters using a 3D MHD background coronal model produced by the MAS (Magnetohydrodynamics Around a Sphere).

To map regions on the shock wave surface, possibly associated with the electron acceleration, we combined 3D shock modelling results with the 3D source positions of the type II burst obtained using the radio triangulation technique. We localize the region of interest on the shock surface and examine the shock wave parameters to understand the relationship between the shock wave and the radio event. We analyzed the evolution of the upstream plasma characteristics and shock wave parameters during the full duration of the type II radio emission. First results indicate that shock wave geometry and its relationship with shock strength play an important role in the acceleration of electrons responsible for the generation of type II radio bursts.
Estimation of the global occurrence rate of elves with Mini-EUSO
Authors: Battisti Matteo , Arnone Enrico , Bertaina Mario , Casolino Marco , Marcelli Laura , Piotrowski Lech Wiktor
Published: March 2021

Elves are the most common type of transient luminous events, with estimates of their global occurrence rate ranging from a few to a few tens per minute. Here, we present the first derivation of the global occurrence rate of elves from Mini-EUSO observations. Mini-EUSO is a wide field of view, space-based telescope operating from a nadir-facing UV-transparent window in the Russian Zvezda module on the International Space Station. It observes the Earth’s atmosphere in the UV band with a spatial resolution of about 6.3 km and a temporal resolution of 2.5 μs. Its optical system made of two 25 cm diameter Fresnel lenses focuses the light into a square array of 48x48 pixels, each pixel being capable of single photon counting. Originally designed to detect the faint fluorescence light produced by extensive air showers induced by extreme energy cosmic rays, it was shown to be capable of detecting a wide range of atmospheric phenomena, including elves. Elves are dynamically traced by Mini-EUSO in their horizontally expanding, fast donut-shaped light emissions and can therefore be unequivocally identified. Mini-EUSO can usually detect elves whose center is just outside the field of view, following the expansion of the ring for hundreds of microseconds. Combining the number of detected elves with consideration of the time and geometries, it is possible to derive a first estimate of their global occurrence rate with Mini-EUSO, and to compare it to the literature. 
Establishing the timings of rainfall-triggered landslides using Sentinel-1 satellite radar data
Authors: Burrows Katy , Marc Odin , Remy Dominique
Published: March 2021

Heavy rainfall can trigger thousands of landslides, which have a significant effect on the landscape and can pose a hazard to people and infrastructure. Inventories of rainfall triggered landslides are used to improve our understanding of the physical mechanisms that cause the event, in assessing the impact of the event and in the development of hazard mitigation strategies. Inventories of rainfall-triggered landslides are most commonly generated using optical or multispectral satellite imagery, but such imagery is often obscured by cloud-cover associated with the rainfall event. Cloud-free optical satellite images may not be available until several weeks following an event. In the case where rain falls over a long period of time, for example during the monsoon season or successive typhoon events, the timing of the triggered landslides is usually poorly constrained. This lack of information on landslide timing limits both hazard mitigation strategies and our ability to model the physical processes behind the triggered landsliding.

Satellite radar has emerged recently as an alternative source of information on landslides. The removal of vegetation and movement of material due to a landslide alters the scattering properties of the Earth’s surface, thus giving landslides a signal in satellite radar imagery. Satellite radar data can be acquired in all weather conditions, and the regular and frequent acquisitions of the Sentinel-1 constellation, could allow landslide timing to be constrained to within a few days.  Satellite radar data has been successfully used in detecting the spatial distribution of landslides whose timing is known a-priori (for example those triggered by earthquakes). Here we demonstrate that time series of Sentinel-1 satellite radar images can also be used to achieve the opposite: the identification of landslide timing for an event whose spatial extent is known.

We analyse radar coherence and amplitude times series to identify changes in the time series associated with landslide occurrence. We compare pixels within each landslide with nearby pixels outside each landslide that have been identified to be similar in pre-rainfall Sentinel-1 and Sentinel-2 imagery. We test our methods on rainfall-triggered landslides in Nepal and Japan, both of which are mountainous countries that experience regular heavy rainfall events that are often obscured by cloud cover in optical satellite imagery.
Extreme sea level oscillations in the Sea of Japan caused by typhoons Maysak and Haishen in September 2020
Authors: Smirnova Daria , Medvedev Igor , Rabinovich Alexander , Šepić Jadranka
Published: March 2021

Two hazardous typhoons, Maysak and Haishen, in September 2020 produced extreme sea level oscillations in the Sea of Japan. These typhoons generated three different types of sea level variations: 1) storm surges (with typical periods from several hours to 1.5 days), 2) extreme seiches (with periods from a few minutes to several tens of minutes), and 3) storm-generated infragravity waves (with periods up to 3-5 min). The data from eleven tide gauges on Russian, Korean, and Japanese coasts were used to examine the properties of these oscillations. The relative contribution of the three separate sea level components and their statistical characteristics (duration, wave heights, and periods) were estimated. The periods of the main eigen modes of individual bays and harbours in the Sea of Japan were estimated based on spectral analysis of longterm background records at the corresponding sites. The results of wavelet analysis show the frequency properties and the temporal evolution of individual sea level components. We found that high-frequency sea level oscillations at stations Preobrazheniye and Rudnaya Pristan have a “white noise” spectrum, caused by the dominance of infragravity waves. A high correlation was detected between the variance of high-frequency sea level oscillations at these stations and the significant wind wave height evaluated from ERA5 for this water area.
Development of hybrid models for the operational retrieval of vegetation traits from the hyperspectral CHIME mission
Authors: Portalés Enrique , Verrelst Jochem , De Grave Charlotte , Amin Eatidal , Reyes Pablo , Morata Miguel , Berger Katja , Tagliabue Giulia
Published: March 2021

The Copernicus Hyperspectral Imaging Mission for the Environment (CHIME) is in preparation to carry a unique visible to shortwave infrared spectrometer. This mission is aimed to be operational, providing routine observations to support agricultural management and biodiversity conservation. In addition to the level 1B, 1C and 2A products, the mission will provide L2B products, i.e. among others including a set of vegetation traits. In view of preparing retrieval models applicable in an operational setting, we developed a hybrid retrieval workflow based on the combination of field data and look-up tables (LUT) generated from radiative transfer models (RTM) at leaf and canopy evel. The presented workflow corresponds to the version 1.8 of the L2B vegetation models. For each variable, the LUT was optimized by an active learning (AL) technique ran against field validation data. This hybrid optimization method is aimed to achieve a good trade-off between specialization, generalism and size of the LUT, in order to perform well in a variety of scenarios and deliver fast processing. Eventually the reduced LUTs were used to train final retrieval models. We selected Gaussian process regression (GPR) and heteroscedastic Gaussian process regression (VHGPR). These are nonlinear, machine learning algorithms that lie in a solid probabilistic framework and not only provide competitive estimates, but also associated uncertainties. Based on this workflow we developed 13 vegetation models of leaf and canopy variables, which are under investigation to be implemented into CHIME’s L2B vegetation processing chain. Models performance was tested in ESA’s CHIME end-to-end (E2E) simulator. Furthermore, we applied the prototype models to images derived from current hyperspectral airborne (APEX and HyPlant) and also spaceborne imagery (PRISMA) resampled to CHIME band settings, resulting into meaningful vegetation maps over heterogeneous European landscapes. For some canopy variables such as fraction of absorbed photosynthetically active radiation (FAPAR), fractional vegetation cover (FVC) and canopy nitrogen content (CNC), we obtained relative errors (NMRSE, in %) of 3.80, 4.25 and 16.83 respectively, and high quality maps. Altogether, obtained maps demonstrate the feasibility of routinely providing vegetation products from the CHIME imaging spectroscopy mission. 

 