bluuebunny/crossref_metadata_2025 huggingface dataset:
Fault kinematic investigations along the Panchkula-Morni region, NW Himalaya, India
Authors: Kumar Ajay , Mukherjee Soumyajit , Shaikh Mohamedharoon A. , Singh Seema
Published: March 2020

The Morni hills located in the north-western Himalaya in Panchkula district, Haryana has undergone poly-phase deformation owing to its complex tectonic history. In order to better understand the kinematic evolution of study area, detailed structural analyses of the fault system at regional-scale is carried out. We perform paleostress analyses on the collected fault-slip data to derive the paleostress tensors. The fault-slip data includes attitudes of fault planes and slickenside lineations, and the sense of slip along the fault plane determined by observing various kinematic indicators. The study area mainly exposes compacted, fine- to medium-grained calcareous sandstones belonging to the lower Siwalik formation in the Himalayan foreland basin. The exposed sandstones contain numerous striated slip planes of varying slip-sense. As the fault planes are intra-formational and exposed in uniform lithology, sense of slip cannot be determined through offset markers. In such cases, the sense of slip of the fault plane is determined solely by observing various slickenside kinematic indicators and fracture types developed on the faulted surface. The slickenside kinematic indicators e.g., calcite mineral steps were found useful in deciphering the sense of movement of each of the slip plane. The paleostress inversion of fault-slip data was carried out by applying the open source software T-Tecto studio X5 to obtain the reduced stress tensor. The Paleostress inversion algorithm called the Right Dihedral Method (RDM) is executed to estimate the principal stress axes orientations. Temporally, the slip planes may have reactivated multiple times preserving multiple slickenside orientations superimposing one another. Such fault-slip data are called heterogeneous and therefore, multiple stress states are deduced to explain the heterogeneous fault-slip data. The paleostress analysis results indicate stress regime index (R’) range 1.25–2.25 and 0.20–1.00 suggesting pure strike-slip to transpressive and pure extensive to transtensive stress regime respectively prevailing in the study area.
Understanding the physical and biological controls on microplastic transport in lakes.
Authors: Elagami Hassan , Frei Sven , Boos Jan-Pascal , Gilfedder Benjamin
Published: March 2020

Microplastics (MPs) have been found ubiquitously in oceanic and terrestrial environments.  As the production and consumption of plastic polymers increases the amount of plastic evading accepted disposal pathways and entering natural systems is also expected to increase. To date the focus of plastic and MP research in particular has been on the ocean, there has recently been a rapid increase in interest in MP levels and distribution in terrestrial systems. However, the focus of existing studies has mostly been on the quantification and distribution of MP contamination in the sediment or on the water column of rivers and lakes. The aim of this project is to investigate the fundamental physical and biological influences on the transport of microplastics (MPs) in lake systems. In particular, we will focus on an understanding of the migration and distribution of MPs, and a systematic investigation on transport and sedimentation of MP in the lake water column. Lab and field experiments are planned to investigate the behavior of different MPs polymers, shapes and sizes under different conditions and determine how this influence the MP transport.

The settling velocity of MPs in stationary water was measured in the laboratory using particle image velocimetry (PIV) which was then compared to manual timing of the sinking velocity. The trajectories of the settling MPs have also been tracked during weak turbulences. In addition, the results were compared with theoretical calculations.

To investigate microbial colonization and biofilm formation on the surface of MPs, samples were exposed on a natural lake environment for varying time periods. The colonization of MP surfaces by microorganisms and their excretion of extracellular polymeric substances (EPS) were examined by laser microscopic techniques and subsequently the effect of the microbiological colonization of settling velocity was determined. In this work we show that the transport of MP is complex, as it is influenced by plastic type, shape, and biological colonization as well as the hydrodynamic conditions in the lake water column.
One million feet view of Level-2 Processing Facility managed at European Centre for Medium-Range Weather Forecasts (ECMWF)
Authors: Prithiviraj Rakesh
Published: March 2020

Title: One million feet view of Level-2 Processing Facility managed at European Centre for Medium-Range Weather Forecasts (ECMWF)

Authors: Rakesh Prithiviraj, Ioannis Mallas, Cristiano Zanna 

Affiliation of authors: European Centre for Medium-Range Weather Forecasts (ECMWF)

Abstract text
Launched in August 2018, European Space Agency’s Aeolus satellite mission measures Earth's wind profile from space. The Aeolus ground segment mainly comprises of:
• Flight Operations Segment (FOS) to monitor and control Aeolus satellite and the instrument onboard, 
• Payload Data Ground Segment (PDGS) for the acquisition and systematic generation of Level-1A and Level-1B products and 
• Level-2 Processing Facility (L2PF) at ECMWF for the generation and dissemination of Level-2B and Level-2C products. 

ECMWF is both a research institute and a 24/7 operational service, producing global numerical weather predictions and other data for our Member and Co-operating States and the broader community. ECMWF relies on its atmospheric model and data assimilation system which is called the Integrated Forecasting System (IFS) to make weather predictions. ECMWF has one of the largest supercomputer facilities and meteorological data archives in the world.

This talk focusses on the Aeolus L2PF facility at ECMWF providing an overview of the processing infrastructure, relevant dataflows, monitoring system and presents the technical/system perspective of Aeolus L2PF in the context of weather forecast. The L2PF facility receives L1B data from Aeolus PDGS and systematically generates and disseminates L2B products and L2C products. The centre is also responsible for the generation of meteorological auxiliary data which is one of the critical inputs for the L2B generation.  The talk also shows various components at ECMWF that work together to achieve more than 99% L2B completeness. The components include ECMWF Production Data Store (ECPDS), ECMWF's High Performance Computing Facility (HPCF) and L2PF cluster. 

The talk concludes with references to tests carried out at ECMWF that have demonstrated that new wind profile observations from Aeolus satellite significantly improve weather forecasts, particularly in the southern hemisphere and the tropics. Because the positive impact of Aeolus on the weather predictions, Aeolus data is expected to be part of the operational weather forecast system at ECMWF in January 2020.
InSAR as an operational tool for remote mine monitoring
Authors: Magnall Nathan , Thomas Adam , Holley Rachel
Published: March 2020

Recent mining disasters, such as the collapse of the Brumadinho tailings dam in Brazil, have placed intense pressure on mining companies to effectively monitor their active and historical assets. Particular focus has been placed on none-profit generating aspects of mines, specifically tailings storage facilities (TSFs). These may be poorly monitored, not routinely maintained, and of unknown construction. Remote sensing techniques present an attractive option for monitoring such facilities, reducing the need for the deployment of expensive ground monitoring systems and personnel.

Here we demonstrate how satellite InSAR can be used as an effective remote monitoring solution for both active and inactive TSFs. InSAR is a powerful tool for mining companies, allowing for both frequent ongoing monitoring and, somewhat uniquely, the ability to look at historical deformation and perform post-event analysis. Furthermore, the increasing availability of satellite data, both commercial and open-access, means that regular monitoring programs are increasingly feasible and economically viable.

The application of InSAR across a mine is by no means without challenges. Active sites typically suffer from poor coherence due to mine activities, while closed sites can be heavily vegetated which further impacts coherence. Despite these challenges, InSAR can be a highly effective component of a mine monitoring program, particularly when integrated with ground based systems.
A comprehensive elastic and fracture model for stratified snowpacks
Authors: Rosendahl Philipp L. , Weißgraeber Philipp
Published: March 2020

Dry snow slab avalanche release depends heavily on the stratification of the snow cover and the mechanical properties of the individual snow layers. This does not only concern the depth and condition of the weak-layer but also the ordering and properties of all snow layers above it.

In order to allow for a quick stability assessment of stratified snow covers, we present an analytical model for snow cover deformations, weak-layer stresses and energy release rates of cracks within the weak-layer for arbitrarily layered snowpacks. In particular, the model covers the impact of the layering order on both the extensional and bending stiffness of the slab. It can be used for skier-loaded slopes and for stability tests such as the propagation saw test. The model is highly efficient and readily allows for parameter studies and implementation into other toolchains.

Recognizing weak-layer collapse as an integral part of the fracture process prior to the release of slab avalanches is crucial and explains phenomena such as whumpf sounds and remote triggering of avalanches from low angle terrain. Finite fracture mechanics introduces a new conceptual understanding of crack nucleation. It provides a coupled stress and energy failure criterion for anticrack formation in persistent weak-layers.

Incorporating this physically sound mixed-mode failure criterion, the model allows for the prediction of skier-loads that layered snowpacks can sustain before weak-layer failure triggering is expected that can lead to avalanche release. Our analysis covers the impact of the layering order on weak-layer stresses and critical skier-loads.
Temperate rainforests near the South Pole during peak Cretaceous warmth
Authors: Klages Johann Philipp , Ulrich Salzmann , Torsten Bickert , Claus-Dieter Hillenbrand , Karsten Gohl , Gerhard Kuhn , Steven Bohaty , Jürgen Titschack , Juliane Müller , Thomas Frederichs , Thorsten Bauersachs , Werner Ehrmann , Tina van de Flierdt , Patric Simões Pereira , Robert Larter , Gerrit Lohmann , Niezgodzki Igor , Gabriele Uenzelmann-Neben , Maximilian Zundel , Cornelia Spiegel ,   Science Team of Expedition PS104
Published: March 2020

The mid-Cretaceous was one of the warmest intervals of the past 140 million years (Myr) driven by atmospheric CO2 levels around 1000 ppmv. In the near absence of proximal geological records from south of the Antarctic Circle, it remains disputed whether polar ice could exist under such environmental conditions. Here we present results from a unique sedimentary sequence recovered from the West Antarctic shelf. This by far southernmost Cretaceous record contains an intact ~3 m-long network of in-situ fossil roots. The roots are embedded in a mudstone matrix bearing diverse pollen and spores, indicative of a temperate lowland rainforest environment at a palaeolatitude of ~82°S during the Turonian–Santonian (93–83 Myr). A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric CO2 contents of 1120–1680 ppmv and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo in high-CO2 climate worlds.
On the upper frequency limit of whistler mode waves observed by low-altitude spacecraft
Authors: Nemec Frantisek , Santolík Ondřej , Parrot Michel
Published: March 2020

Frequency-latitude plots of electromagnetic wave intensity in the very low frequency range (VLF, up to about 20 kHz) observed by the low altitude DEMETER spacecraft are analyzed. Apart from electromagnetic waves generated by plasma instabilities in the magnetosphere, a significant portion of the detected wave intensity comes from ground-based lightning activity and VLF military transmitters. These whistler mode waves are observed not only close to source locations, but also close to their geomagnetically conjugated points. There appears to be an upper frequency limit of such emissions, where the wave intensity substantially decreases. Its frequency roughly corresponds to half of the equatorial electron cyclotron frequency at a respective magnetic field line, suggesting a relation to wave ducting in ducts with enhanced density. However, it seems to exhibit a non-negligible longitudinal dependence and it is different during the day than during the night. We use a realistic model of the Earth’s magnetic field to explain the observed variations. We interpret the observations in terms of ducted/unducted wave propagation, and we compare the wave intensities in the source hemisphere with those measured in the hemisphere geomagnetically conjugated.
Global radioxenon emission inventory for 2014
Authors: Kalinowski Martin
Published: March 2020

Global radioactivity monitoring for the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) includes the four xenon isotopes 131mXe, 133Xe, 133mXe and 135Xe. These four isotopes are serving as important indicators of nuclear explosions. The state-of-the-art radioxenon emission inventory uses generic release estimates for each known nuclear facility. However, the release amount can vary by several orders of magnitude from year to year. The year 2014 was selected for a single-year radioxenon emission inventory that avoids this uncertainty. Whenever 2014 emissions reported by the facility operator are available these are incorporated into the 2014 emission inventory. This presentation summarizes this new emission inventory. The overall emissions by facility type are compared with previous studies. The global radioxenon emission inventory for 2014 can be used for studies to estimate the contribution of this anthropogenic source to the observed ambient concentrations at IMS noble gas sensors to support CTBT monitoring activities, including calibration and performance assessment of the verification system as described in the Treaty as well as developing and validating methods for enhanced detection capabilities of signals that may indicate a nuclear test. One specific application will be the third ATM Challenge that was announced in December 2019.
Using Ghost Fronts to Predict the Arrival Time of CMEs during 13-17 June 2012
Authors: Chi Yutian , Scott Chris , Shen Chenglong , Wang Yuming
Published: March 2020

Coronal mass ejections (CME) are large-scale eruptions of magnetized plasma and huge energy through the corona and out into interplanetary space.

A mount of CMEs observed by HI-1 cameras present two fronts that are similar in shape but separated by a few degrees in elongation. Scott et al. (2019) interpret the ghost fronts as projections of separate discrete sections of the physical boundary of the  CME. Ghost fronts could provide information about the longitudinal shape of CME in the field of view of Hi- 1, which can be used to improve the forecast of the arrival time of ICME. During 13-15 June 2012, STEREO/SECCHI recorded two successive launched Earth-directed CMEs. Both of the two CMEs show clearly two fronts in HI-1 images. We use the ghost fronts to predict the arrival time of the two CMEs and utility the in-situ measurements from VEX and Wind to verify the accuracy of the prediction of ghost fronts model. 
Fertilizer N rates to optimize bioenergy feedstock production and water quality in semi-arid environments
Authors: Allen Brett , Sainju Upendra , Jabro Jay
Published: March 2020

Renewable bioenergy feedstocks offset the demand for conventional petroleum-based energy resources. Switchgrass (Panicum virgatum L.) is a warm-season perennial C4 grass that has been utilized for lingo-cellulosic ethanol production and direct energy via combustion. However, little is known about its potential as a feedstock in the semi-arid northern Great Plains USA, including the impact of N fertilizer application on biomass production and on environmental quality. A field study initiated in 2009 seeded ‘Sunburst’ switchgrass into 12.2 m by 30.5 m plots. Split plots randomized within each main plot included fertilizer N broadcast each spring at 0, 28, 56, and 84 kg N per ha as urea, with four treatment replicates. Aboveground biomass, allowing a 20 cm stubble height, was harvested, weighed, and dried at 55 deg C each fall beginning in 2011 from four randomly selected 0.25 m sq areas. Soil cores were taken to a depth of 1.2 m in fall 2018, air-dried, and analyzed for soil nitrate. Switchgrass biomass ranged from 1.8 to 12.3 Mg per ha. In most years, N application increased switchgrass biomass, but response to N rates above 28 kg per ha was inconsistent. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control.  Soil nitrate levels indicated the potential of (over)fertilization of switchgrass feedstocks to impact water resources in semi-arid environments.
Svalbard's Arctic Settlements: From Mining Sites to Urbanized Environments
Authors: Baciu Dan , Abramova Anna
Published: March 2020

A century ago, Svalbard became the northernmost permanently inhabited Arctic archipelago when international treaties allowed multiple nations to extract coal and exploit the lands. The first settlements were founded as industrial production bases. Meanwhile, mining has gradually declined, but the previous settlements have become urbanized, which opens wholly new perspectives for Svalbard’s present and future: A new university center is thriving; and local media and tourism industries are expanding. Local authorities use these developments to quantify urban growth in the last decades. They hope that this growth will eventually substitute previous mining activities and point towards a future that could make Svalbard a prime example of sustainable urbanization in the Arctic. We integrate novel digital humanities techniques with historical analysis and chemical screening of snowpack, which makes it possible to holistically evaluate the interplay between multiple layers of urbanization, tourism, research initiatives, and mining activities and relics as integral parts of a larger and constantly evolving cultural multifold. From this vantage point of view, a double-phased evolution becomes identifiable. In the 20th century, Svalbard’s urban and cultural life diversified. The urban growth observed in the 21st century is a result of this initial diversification. This new perspective may help local authorities manage urban growth. In particular, we attract attention to urban and cultural diversification and suggest that diversity is a source for urban growth, rather than a mere byproduct thereof. In addition, the new results also constitute a further test for our previous work on Svalbard and on cultural diversification. In previous conference contributions, we showed that persistent environmental awareness formed in Svalbard only long after mining activity affected the environment. We now continue along these lines by proposing that the formation of persistent environmental awareness is only part of urban and cultural diversification, which includes the rise of diverse local cultures and identities. Beyond Svalbard, our past and present work may help policy makers and populations around the world understand diversification processes and their impact on urban and cultural growth.

 
Are artificial reefs an appropriate solution to protect the Danube Delta coast?
Authors: Dinu Irina
Published: March 2020

Are artificial reefs an appropriate solution to protect the Danube Delta coast?

Irina Dinu1, Vicente Gràcia2, Manuel García-León3, Adrian StÄƒnicÄƒ1

 

1 – National Institute for Marine Geology and Geoecology (GeoEcoMar), 23-25 Dimitrie Onciul St., 024053, Bucharest, Romania

2 - Laboratory of Maritime Engineering, Polytechnic University of Catalonia (LIM-UPC), Campus Diagonal Nord, Building D1, 1-3 Jordi Girona St., 08034 Barcelona

3 - International Centre for Research of Coastal Resources (CIIRC), 1-3 Jordi Girona St., Mòdul D1, Campus Nord, 08003 Barcelona, Spain

 

The Danube Delta coast is part of the Danube Delta Biosphere Reserve, thus being aimed to preserve its typical natural habitats. Over the last decades, human interventions along the Danube River, as well as coastal navigation and harbour protection works on the Romanian coast have determined the reduction of sediment supply along the Danube Delta coast, which is nowadays affected by erosion on its widest part.

Sustainable management plans for the Danube Delta coast include the use of working-with-nature solutions.

In this work, the effect of artificial reefs on the wave heights along the Danube Delta coast is studied. The results of a previous wave climate study and a wave model have been used for this purpose. Simulations have been performed for different setup of artificial reefs and for extreme storms with various return periods. The effect of sea level rise has also been taken into account.

Our results show that artificial reefs are significantly effective in reducing the wave heights along the Danube Delta coast. However, further detailed analysis concerning the impact of such a coastal protection solution is still needed.  
Source Altitudes of Optical Emissions Associated with TGFs
Authors: Heumesser Matthias , Chanrion Olivier , Neubert Torsten , Dimitriadou Krystallia , Köhn Christoph , Gordillo-Vazquez Francisco J. , Luque Alejandro , Pérez-Invernón Francisco Javier , Christian Hugh , Blakeslee Richard J. , Østgaard Nikolai , Mezentsev Andrey , Marisaldi Martino
Published: March 2020

Terrestrial Gamma-Ray Flashes (TGFs) observed from space appear to be generated after a few milliseconds of optical activity and before the onset of a main optical pulse. The pre-activity is thought to be from a propagating leader and the main optical pulse the emissions from the ensuing stroke. Scattering of photons in the cloud increases the rise time and durations of the pulses and thus allows for estimates of their optical path from their sources.

In this presentation we estimate the depth inside thunderclouds of pulses associated with more than 100 TGFs observed by the Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS). The observations are in narrow bands at 337 nm, to include the strongest line of N22P and 777.4 nm of OI, considered a strong lightning emission line. With the assumption that the sources are instantaneous and at single points within a cloud, we find optical paths for the events by using typical cloud properties. Combined with cloud top heights from a recent study on TGF producing thunderstorms, this gives an estimate at which altitude the optical detections are produced.

Data from VAISALA’s lightning location network GLD360 and NASA’s Lightning Imaging Sensor on the ISS (ISS-LIS) will be used to assess the results from the optical analysis. This includes investigations of the correlations between TGF durations, detected peak lightning current and optical path in the cloud.
Evidence for polar surface-water incursions into the Gulf of Cadiz (SW Iberia) during the Early-to-Mid Pleistocene Transition
Authors: Mega Aline , Salgueiro Emilia , Voelker Antje Helga Luise
Published: March 2020

The Mid Pleistocene Transition (MPT) was a global climatic event characterized by a drastic change in the deep thermohaline circulation during the glacial periods that resulted in more intense and longer lasting cold periods and cooler sea-surface temperature (SST). These changes might be linked to the atmospheric pCO2 reduction which in turn led to colder atmospheric temperatures and the expansion of continental ice sheets. In the mid-latitude North Atlantic, high-resolution records documenting the MPT's impact are still limited. Thus, this study's objective is to contribute to the knowledge by reconstructing circulation changes in the subtropical gyre realm off the southwestern Iberian Margin.  We use planktonic foraminifera faunal data from Integrated Ocean Drilling Program (IODP) Site U1387 (Faro Drift, Gulf of Cadiz) to characterize centennial-scale SST variations during the interval from Marine Isotope Stage (MIS) 18 to MIS 28. The results indicate relative stable SSTs during the interglacial and interstadial periods with temperatures around 20°C during summer and 16°C during winter. During MIS 20, 22, 24, and 25 short-termed extreme cold events were recorded when winter temperatures dropped below 5°C, during late MIS 22 even close to 0°C. They mark the terminal stadial events during deglaciation and were related to increased abundance of polar planktonic foraminifera species N. pachyderma that reached values near to 80%. N. pachyderma values. Percentages of that species between 90 and 50% can be found in the polar regions near the Arctic Front and those between 50 and 5% are indicative of subarctic waters. Whereas the terminal stadial events and the first stadial phase of MIS 22 were marked by incursions of polar surface waters to the southern Iberian margin, abrupt cold events during periods of continental ice shield growth of MIS 19, 21, 25 and 28 were associated with subarctic surface waters. During the MPT, the waters off southern Iberia, therefore, experienced cooling events more extreme than during the last glacial cycle.
Ground scientific verification test for High Resolution Imaging Camera of China's First Mars Mission
Authors: Yan Wei , Liu Jianjun , Zhang Xiaoxia , Liu Dawei , Liu Donghao
Published: March 2020

Mars is a planet in the solar system that is closer to the Earth and has the most similar natural environment to the Earth. It has always been the first choice for humans to go out of the Earth and Moon system for deep space exploration.

China’s First Mars Mission (HX-1) will be launched in 2020 with an orbiter and a lander rover. One of the scientific goals of our mission is to study the morphology and geologic structure of the Mars. In order to achieve this purpose, the orbiter is equipped with a High Resolution Imaging Camera (HiRIC) to obtain the high-resolution morphology data of typical regions and to study the formation and evolution of geologic structure. HiRIC consists of three TDI CCD line-scan detectors and two COMS area-array detectors. Each TDI CCD detector covers 5 spectral bands. Its main working mode is the panchromatic TDI CCD push-scan imaging with a maximum spatial resolution of 0.5m.

Ground scientific verification test is an effective way to comprehensively evaluate the performance, data quality of HiRIC, and to fully verify its on-orbit detection process and data processing methods. In this study, contents and results of ground scientific verification test for HiRIC is introduced. The engineering model is used here for image motion compensation effect evaluation test, focusing effect evaluation test, and outdoor field imaging test. The results show that, 1) HiRIC can calculate the image motion compensation parameters and control the camera imaging correctly according to the platform parameters of orbiter; 2) Focus processing is effective, and HiRIC can adapt to the high-resolution imaging needs of different orbit altitudes; 3) Clear image data can be obtained according to the on-orbit detection process in the outdoor field imaging test, and image data processing was correct. Image data quality, compression quality, and TDI CCD stitching accuracy all meet the requirements of the verification test. This test fully evaluated HiRIC's ability to obtain high-resolution image data of the surface of Mars.
A framework of abrupt changes and trends detection for rainfall erosivity
Authors: Qian Feng , Hu Bo , Liu Honghu , Liu Jingjun
Published: March 2020

Rainfall erosivity (R factor), in the Universal Soil Loss Equation (USLE) , a climate index, is used worldwide to assess and predict the potential of rainfall to cause erosion. The temporal variation in rainfall erosivity, informs of abrupt change and trend, are critical for soil loss prediction. To find a simple and effective method for accurate detection of abrupt change and trend has implication for soil and water conservation planning. In this paper, a four-step framework is proposed to detect abrupt change and trend in rainfall erosivity time series, i.e., evaluate the significance of variation in rainfall erosivity time series at three levels: no, weak and strong, abrupt change and trend detection for rainfall erosivity,  estimation of correlation coefficient between the variation component and rainfall erosivity series, remove the variation component with the largest correlation coefficient from the rainfall erosivity series, repeat the above steps for the new series until variance coefficient was insignificance. The first step is based on an index of Hurst coefficient. The trend detection is implemented using both Spearman rank and Kendall rank correlation test. For abrupt change ,three kinds of methods (Mann-Kendall, Moving T and Bayesian test) are employed.  This framework is applied to the annual rainfall erosivity series of the Three Gorges Reservoir , China. There was a large uncertainty in detecting variability with a single test method. Application of the proposed framework can reduce uncertainty  associated with soil erosion assessment and achieve more accurate regional soil and water management. 
Spatial variability of surface sediments on the eastern continental margin of Korea
Authors: Um Inkwon
Published: March 2020

Total 99 surface sediment samples were obtained from eastern continental margin of Korea from Uljin to Busan below water depth 500 m to investigate the spatial variability of surface sediments. Mean grain size (Mz) of surface sediments ranges from 1.74 to 9.70 Φ (mean of 6.19±2.28 Φ), fine-grained sediments were mainly deposited along the coastal line on the Korea Strait Shelf Mud (KSSM) and Hupo Basin, whereas, coarse-grained sediments were covered on the Hupo Bank and southern continental margin. TOC content of surface sediments ranges from 0.09 to 3.27% (mean of 1.36±0.83%) and spatial variation is similar with that of Mz. Spatial distribution patterns of Al (1.56~10.98 %), K (0.94~3.29%), Ti (0.04~0.37%), Ni (1.97~38.18 mg/kg), Co (1.28~14.31 mg/kg), Cs (0.78~10.47 mg/kg), and total REEs (39.11~173.80 mg/kg) were also similar with that of Mz (r > 0.70). Generally, contents of geochemical element were lower in coarse-grained sediments on the Hupo Bank and southern continental margin and relatively higher in fine-grained sediments on the KSSM and Hupo Basin. On the contrary, Ba (126.58~476.35 mg/kg) showed opposite pattern, high Ba contents were observed in coarse-grained sediments on the Hupo Bank and southern continental margin while, lower contents showed in fine-grained sediments. Surface sediments of the eastern continental margin of Korea could be divided into four types based on characteristics of geochemical element: Type I sediments were obtained from on the Hupo Bank and outer shelf/shelf break of the southern continental margin and might be composed with relic sediments formed during the Miocene and/or Last Glacial Maximum. Type II sediments were obtained from outer shelf of the southern continental margin especially beside of the Korea Trough and believed to be coarse-grained sediments deposited during the glacial age derived through the Korean Trough. Type III sediments which covered on the KSSM were mostly composed with fine-grained sediments. KSSM was deposited during the Last Glacial Maximum and consist of mixtures of sediments discharged from Chinese rivers and Nakdong River. Type IV sediments were mostly covered on the Hupo Basin. Sediments on the Hupo Basin were deposited during the Quaternary but sediment provenance should be differ from KSSM and it might be originated from small streams near the Hupo Basin.
Stilling and Recovery of the Surface Wind Speed Based on Observation, Reanalysis, and Geostrophic Wind Theory over China from 1960 to 2017
Authors: Zhang Zhengtai , Wang Kaicun
Published: March 2020

Surface wind speed (SWS) from meteorological observation, global atmospheric reanalysis, and geostrophic wind speed (GWS) calculated from surface pressure were used to study the stilling and recovery of SWS over China from 1960 to 2017. China experienced anemometer changes and automatic observation transitions in approximately 1969 and 2004, resulting in SWS inhomogeneity. Therefore, we divided the entire period into three sections to study the SWS trend, and found a near zero annual trend in the SWS in China from 1960 to 1969, a significant decrease of -0.24 m/s decade-1 from 1970 to 2004, and a weak recovery from 2005 to 2017. By defining the 95th and 5th percentiles of monthly mean wind speeds as strong and weak winds, respectively, we found that the SWS decrease was primarily caused by a strong wind decrease of -8 % decade-1 from 1960 to 2017, but weak wind showed an insignificant decreasing trend of -2 % decade-1. GWS decreased with a significant trend of -3 % decade-1 before the 1990s, during the 1990s, GWS increased with a trend of 3 % decade-1 whereas SWS continued to decrease with a trend of 10 % decade-1. Consistent with SWS, GWS demonstrated a weak increase after the 2000s. After detrended, both of SWS and GWS showed synchronous decadal variability, which is related to the intensity of Aleutian low pressure over the North Pacific. However, current reanalyses cannot reproduce the decadal variability, and can not capture the decreasing trend of SWS either.
Identification of electromagnetic pre-earthquake perturbations from the DEMETER data by AI technologies
Authors: Xiong Pan , Long Cheng , Zhou Huiyu , Battiston Roberto , Zhang Xuemin , Shen Xuhui
Published: March 2020

Many examples of ionospheric perturbations observed in large seismic events were recorded by the low-altitude satellite DEMETER. In this paper, we explore 16 spot-checking classification algorithms, among which, the top classifier with low-frequency power spectra of electric and magnetic fields were used for ionospheric perturbation analysis. Satellite data spanning over about 6 years has been analyzed and about 8,760 earthquakes with magnitudes larger than or equal to 5.0 that occurred all over the world during the analyzed period have been included in the study. We discover that among these methods, gradient boosting based method called LightGBM outperforms the other state-of-the-art methods and achieves AUC (the Area Under the Curve) of 0.9859 and accuracy of 95.01% in a five-fold cross-validation test on the benchmarking datasets. In addition, the LightGBM method shows a strong capability in discriminating electromagnetic pre-earthquake perturbations over different earthquake databases. The results show that electromagnetic pre-earthquake data with the location in its circular region with its center at the epicenter and a radius given by the Dobrovolsky’s formula and the time of a few hours before the shocks is more useful in discriminating electromagnetic pre-earthquake perturbations. Moreover, we observe that during nights, some low-frequency intervals of electric and magnetic fields are the dominant features as rendered by the trained LightGBM model. These observations support the viewpoint that the seismic activities lead to the enhancement of lightning activity and low frequency electromagnetic pre-earthquake data can help us to detect seismic events.
How will the next eruption in Tenerife affect aviation?
Authors: Prieto Alberto , D'Auria Luca , Macedonio Giovanni , Hernández Pedro Antonio , Hernández William
Published: March 2020

During a volcanic eruption, one of the most relevant threat for civil aviation is the dispersion of volcanic ash in the atmosphere. All the aircraft are susceptible to suffer damages from volcanic ash even at low concentrations. The economy of Canary Islands (Spain) strongly depends on tourism, so it is of fundamental importance to estimate the consequences of a possible eruptive scenario of the air traffic in the archipelago and consequently on the tourism. We made an exhaustive study about the impact of volcanic ashes on aviation for one of the most important islands in the archipelago: Tenerife.

We developed a large set of numerical simulations of small-magnitude eruptions in Tenerife, which are the most probable eruptive scenario in this island. Our main goal is to develop a probabilistic approach to evaluate the airports most affected by dispersion and fallout of volcanic ash. We carried out more than a thousand simulations with the software FALL3D using supercomputing facilities of Teide-HPC from the Instituto Tecnológico y de Energías Renovables (ITER). In order to model the small-magnitude eruptions, we calculated datasets of total mass of volcanic ash erupted and eruption lengths using a bivariate empirical probability density function obtained using Kernel Density Estimation (KDE) from data of historical eruptions in Tenerife. The vent positions were selected following the density of vents related to Holocene eruptions. Granulometries were chosen following Bi-Gaussian distribution of particle size ranging from Φ=-1 to Φ=12, where Φ=-log2d (diameter in mm). The number of eruptive phases within each eruption is selected randomly. We have split equally the total eruptive duration into these eruptive phases and we set a gaussian distribution in the centre of each division. After that, the intersection between each eruptive phase is chosen taking into account these gaussian distributions to have eruptive phases with different duration.

All the simulations are coupled with ERA-Interim meteorological reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We have implemented a probabilistic procedure to map in 3D the hazard associated to volcanic ash. For this purpose, we calculated concentration percentiles (P25, P50 and P75) and time intervals of high concentrations of volcanic ash to evaluate the hazard of suspended ash in the volume surrounding the major airports in Tenerife.
Structures of Different Tibetan Plateau Vortex Types
Authors: Feng Xinyuan , Liu Changhai , Fan Guangzhou , Zhang Jie
Published: March 2020

A Tibetan Plateau vortex (TPV) is defined as a shallow cyclonic meso-α-scale low-pressure system that originates over the main body of the Tibetan Plateau in the warm season and presents most notably at 500 hPa. It is the main precipitation-inducing weather system over the plateau in the warm season.

Knowledge of the TPV structure is of considerable importance for understanding the generation and development mechanisms of this mesoscale system. However, our understanding of vortex structures and our ability to classify them on a physical basis is limited due to insufficient observations. The high-resolution NCEP Climate Forecast System Reanalysis (CFSR) dataset is used in the present paper to investigate the general structural features of various types of mature TPV through classification and composite structure analysis. Results indicate that the dynamic and thermodynamic structures show regional and seasonal dependency, as well as being influenced by attributes of translation, associated precipitation, and the South Asian high (SAH).

The common precipitating TPV (type I), frequently occurring in the west–east-oriented zonal region between 33° and 36°N, is a notably low-level baroclinic and asymmetric system. It resides within a large-scale confluent zone and preferentially travels eastwards, potentially moving out of the plateau. The heavy rain vortex (type II) corresponds to a deep vortex circulation occurring in midsummer. The low-level baroclinic sub-category (type IIa) is associated with a low-level jet and mainly originates in the area (32°–35°N, 86°–94°E), preferentially moving east of 90°E and even away from the plateau; meanwhile, the nearly upright sub-category (type IIb), which has a cold center at low levels and a warm center at mid-upper levels, is a quasi-stationary and quasi-symmetric system favorably occurring west of 92°E. A western-pattern SAH exists in the upper troposphere for these two sub-categories. The springtime dry vortex in the western plateau (type III) is warm and shallow (~100 hPa deep), and zonal circulation dominates the large-scale environmental flows in the middle and upper troposphere. The precipitating vortex in the southern plateau occurring during July–August (type IV) is not affected by northerly flow at low levels. It is vertically aligned and controlled by a banded SAH.
Sedimentary signals of the upwelling along the Zhejiang coast, China
Authors: Zhang Xin , Liu Jian , Saito Yoshiki
Published: March 2020

The muddy deposits of the Zhe-Min coastal area are of great importance to understand "source to sink" processes. However, the sedimentary processes that dominate along the Zhejiang coast remain controversial. Determining sedimentation rates is an important element of our understanding of sedimentary processes and deposition patterns. Therefore, 23 vibrocores were collected from the muddy area along the Zhejiang coast to analyse their sedimentation rates using 210Pb geochronology. The spatial distribution of the sedimentation rates derived from the 23 vibrocores, as well as previously published data, demonstrated that the middle part of the study area around 29°N experienced relatively high sedimentation rates, which has never been reported in previous studies. This location of high sedimentation rates is approximately consistent with that of the Holocene maximum thickness deposition, finest surface sediments and high concentration of chlorophyll, resulting from the existence of upwelling along the Zhejiang coast besides the fluvial inputs. 
Tropical Cyclones in European Seasonal Forecast Models
Authors: Hodges Kevin , Befort Daniel , Weisheimer Antje
Published: March 2020

This study assesses the representation of Tropical Cyclones (TC) in an ensemble of seasonal forecast models from five different centres (ECMWF, UK Met Office, DWD, CMCC, Météo-France). Northern Hemispheric Tropical Cyclones are identified using a widely applied objective Tropical Cyclone tracking algorithm based on relative vorticity fields. Analyses for three different aspects are carried out: 1) assessment of the skill of the ensemble to predict  the TC frequencies over different ocean basins, 2) analyse the dependency between the model's ability to represent TCs and large-scale biases and 3) assess the impact of stochastic physics and horizontal resolution on TC frequency.

For the July to October season all seasonal forecast models initialized in June are skilful in predicting the observed inter-annual variability of TC frequency over the North Atlantic (NA). Similarly, the models initialized in May show significant skill over the Western North Pacific (WNP) for the season from June to October. Further to these significant positive correlations over the NA, it is found that most models are also able to discriminate between inactive and active seasons over this region. However, despite these encouraging results, especially  for skill over the NA, most models suffer from large biases. These biases are not only related to biases in the large-scale circulation but also to the representation of intrinsic model uncertainties and the relatively coarse resolution of current seasonal forecasts. At ECMWF model uncertainty is accounted for by the use of stochastic physics, which has been shown to improve forecasts on seasonal time-scales in previous studies. Using a set of simulations conducted with the ECMWF SEAS5 model, the effects of stochastic physics and resolution on the representation of Tropical Cyclones on seasonal time-scales are assessed. Including stochastic physics increases the number of TCs over all ocean basins, but especially over the North Atlantic and Western North Pacific.
Tsunami source consideration of the 1662 Hyuga-nada earthquake occurred off Miyazaki Prefecture, Japan
Authors: Ioki Kei , Yamashita Yusuke , Kase Yoshihiro
Published: March 2020

Hyuga-nada region is located at the south-western part of Nankai Trough, in the Pacific Ocean. M7-class interplate earthquakes are repeatedly occurred by the subducting Philippine Sea plate beneath the Eurasian plate. The largest earthquake in this area was the 1662 Hyuga-nada earthquake (M=7.6) which occurred off Miyazaki Prefecture, south-eastern area of Kyushu region, Japan, and generated tsunami (after called the 1662 tsunami). Strong ground motion hit and many structures were broken near the coast of Miyazaki Prefecture. The tsunami heights were estimated at least 4-5 m along the coast of Miyazaki city, and more than 200 people died by the earthquake and tsunami by historical records. This region is also active area of the shallow slow earthquakes. The 1662 tsunami was much larger than tsunamis generated by usual M7-class interplate earthquakes. It is known by the 2011 Tohoku earthquake that focal area of shallow slow earthquakes also become a tsunami source area. So, we hypothesized that the 1662 unusual large tsunami was caused by the coseismically slipping of focal area of shallow slow earthquakes. We firstly constructed the fault model of the 1662 earthquake based on the recent result of geophysical observation. To examine the tsunami source of the 1662 earthquake, we surveyed the 1662 tsunami deposits in the lowland along the coast of south-eastern Kyushu region. As a result, sandy event deposits interbedded with clay (organic clay) were recognized at several surveyed points. Based on facies features, these event deposits were possibly formed by the 1662 tsunami. Numerical simulation of the tsunami was carried out using the constructed fault model. Calculated tsunami inundation area can explain distribution of the likely tsunami event deposits at Komei, Miyazaki Prefecture. Furthermore, this study compares calculated tsunami inundation areas, distribution of other surveyed tsunami deposits and tsunami heights of historical records. Tsunami source of the 1662 earthquake proposed by our study could better explain geophysical, geological and historical records.