bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconstructing a hydraulic model for historic flood levels in the city of Bath, United Kingdom
Authors: Stamataki Ioanna , Kjeldsen Thomas
Published: March 2020

Assessing the risk of future flood events and the implications for flood risk in cities is an economically and socially costly problem. In this research, we assess the utility of documentary evidence of past flood events for contemporary flood risk assessments to reduce the uncertainty in flood frequency estimation due to the interpolation from short annual maximum series (AMS) records.

The historical city of Bath, United Kingdom, developed in close relation to the River Avon, and evidence of flooding in the city of Bath can be traced back to Roman occupation. For this research a particularly rich record of historical evidence was chosen occurring from the 19th century onwards with flood marks on buildings through-out the city as well as documentary evidence in contemporary newspapers and technical reports. The earliest flood mark found in the city of Bath dates to 1823 with 15 more extreme floods after that marked as well. The extensive flooding in 1947 initiated work on what eventually became the present-day Bath flood protection scheme (BFS) which was implemented after the 1960 catalyst flood event.

Using an existing one-dimensional hydraulic model representing the current hydraulic system of the River Avon in Bath, a historical survey of how the river and its management has changed over time was conducted. The model was developed using historical evidence (e.g. maps, flood marks, photographs, newspaper articles etc), surveyed river cross sections, recorded and design hydrographs from National datasets.

The 1960 flood is reconstructed numerically using all available data, from flood marks to old surveyed river cross sections.  The resulting hydraulic model is used to investigate the effect of the Bath Flood Defence Scheme. Sensitivity studies with different values for the roughness coefficient are also presented in order to assess the uncertainty on water levels during extreme events. Finally, the numerically reconstructed historical peak flood discharge is compared with the results obtained using a simple Manning equation approach to assess the two methods. This paper demonstrates how hydraulic modelling can be applied to historical data and offers considerable potential to further investigations in the improvement of design flood flows.
Integrated Science Operations of CASSIOPE e-POP with the Swarm Constellation for New Studies of Magnetosphere-Ionosphere Coupling
Authors: Yau Andrew , Howarth Andrew , James H. Gordon , Knudsen David , Langley Richard , Miles David
Published: March 2020

The CASSIOPE Enhanced Polar Outflow Probe (e-POP) was originally envisioned as a low-cost, short-lifetime (18-month) small-satellite mission for investigating polar ion outflows and related magnetosphere-ionosphere coupling phenomena. However, e-POP is currently in its seventh year of continuing operation, as an addition to and as the fourth component of the Swarm constellation of satellites, under the European Space Agency Third Party Mission Programme.

Since 2017, the increased operation duty-cycle of e-POP has enabled the routine extension of its science operations to its full altitude range and to all latitudes, and made possible several new studies of important mid- and low-latitude topside ionospheric phenomena. In addition, the integrated e-POP and Swarm operation takes advantage of the synergy between the orbit characteristics and unique instrument capabilities between e-POP and Swarm, to enable or enhance a host of coordinated studies of magnetosphere-ionosphere coupling: including the Earth’s magnetic field and related current systems, auroral and upper atmospheric dynamics, and ionosphere-thermosphere and ionosphere-plasmasphere coupling processes. We present an overview of these new studies, focusing on their results on the effects of space weather in the ionosphere and upper atmosphere such as anomalous satellite orbit drag and ionospheric scintillation.
Intraseasonal Transitions of the Wintertime Pacific Jet Stream
Authors: Madsen Maria , Martin Jonathan
Published: March 2020

The deficiency in predictability at subseasonal-to-seasonal timescales, as compared to prediction at conventional weather prediction timescales, is significant. Intraseasonal variability of atmospheric features like the jet stream, occurring within this gap, lead to extreme weather events that present considerable hazards to society. As jets are an important feature at the interface of the large-scale general circulation and the life cycle of individual weather systems, there is strong incentive to more comprehensively understand their variability.

The wintertime Pacific jet manifests its intraseasonal variability in two predominant modes: a zonal extension or retraction and a meridional shift by as much as 20° of the jet exit region. These two leading modes are associated with basin-scale anomalies in the Pacific that directly impact weather in Hawaii and continental North America. Although recent work has demonstrated the impact intramodal changes of the Pacific jet have on large-scale structure, sensible weather phenomena, and forecast skill in and around the vast North Pacific Basin, the transitions between the leading modes have hardly been considered and, therefore, are poorly understood. Consequently, this work examines the nature and predictability of transitions between modes of wintertime Pacific jet variability as well as their associated synoptic environments.

We apply two distinct but complementary statistical analyses to 70 cold seasons (NDJFM 1948/49-2017/18) of daily 250-hPa zonal winds from the NCEP/NCAR Reanalysis to investigate such transitions. Empirical orthogonal analysis (EOF)/principal component (PC) analysis is used to depict the state of the daily Pacific jet as a point in a two dimensional phase space defined by the two leading modes.  Supporting this technique is a self-organizing maps (SOMs) analysis that identifies non-orthogonal, synoptically recurring patterns of the Pacific jet. Together, these analyses show that there are, in fact, preferred transitions between these leading modes of variability. Composite and individual case analyses of preferred transition evolutions provides new insight into the synoptic-scale environments that drive Pacific jet variability.
TGF: A New MATLAB-based Software for Terrain-related Gravity Field Calculations
Authors: Yang Meng , Hirt Christian , Pail Roland
Published: March 2020

With knowledge of geometry and density-distribution of topography, the residual terrain modelling (RTM) technique has been broadly applied in geodesy and geophysics for the determination of the high-frequency gravity field signals. Depending on the size of investigation areas, challenges in computational efficiency are encountered when using an ultra-high-resolution digital elevation models (DEM) in the evaluation of Newtonian integration. This paper presents a new MATLAB-based program, terrain gravity field (TGF), for the accurate and efficient determination of the terrain-related gravity field based on an adaptive algorithm. Depending on the attenuation character of gravity field with distance, the adaptive algorithm divides the integration masses into four zones, and adaptively combines four types of geometries and DEMs with different spatial resolutions. The most accurate but least efficient polyhedron together with the finest DEM are only considered for the innermost zone, while prism approximation for the second zone, the third zone with the more efficient tesseroid and a coarse DEM, and the most efficient but least accurate point-mass with the coarsest DEM for distant masses. Compared to some publicly available algorithms depending on one type of geometric approximation, the TGF achieves accurate modelling of gravity field and greatly reduces the computation time. Besides, the TGF software allows to calculate ten independent elements of gravity field, supports two types of density inputs (constant density value and digital density map), and considers the sphericity of the Earth by involving spherical approximation and ellipsoidal approximation. Further to this, the TGF software is also capable of delivering the gravity field of full-scale topographic gravity field implied by masses between the Earth’s surface and mean sea level. Results from internal and external numerical validation experiments of TGF confirmed its accuracy of sub-mGal level. Based on TGF, the trade-off between accuracy and efficiency, values for the spatial resolution and extension of topography models are recommended. The TGF software has been extensively tested and recently been applied in the SRTM2gravity project to convert the global 3” SRTM topography to implied gravity effects at 28 billion computation points. This confirms TGF the capability of dealing with large datasets.
Monthly semi-distributed hydrological model at national scale in Peru
Authors: Llauca Harold , Lavado Waldo , Montesinos Cristian , Rau Pedro
Published: March 2020

Surface water resources in Peru are heterogeneously distributed in three drainage areas (Pacific, Titicaca, and Atlantic), and their quantification is relevant for planning in economic activities such as water supply and agriculture. However, their continuous monitoring at national scale becomes difficult due to the low stream gauges density and short streamflow records. The aim of this work is to generate a database of simulated monthly streamflows at a national scale from January 1981 to December 2016, applying the parsimonious GR2M model in a semi-distributed approach, under a parameter regionalization scheme. For this, 3594 sub-basins (~300 km2) located in the three drainage areas were tested. These sub-basins were first grouped in 14 calibration regions based on a sensitivity analysis of the runoff ratio (RR) and runoff variability (RV) indexes derived from the GR2M outputs. The model was forced with monthly gridded-data of precipitation and potential evapotranspiration from the PISCO product (Peruvian Interpolated data of the SENAMHI’s Climatological and hydrological Observations) and was calibrated and validated with 38 stream gauges using the Kling-Gupta (KGE) metric. After the parameter regionalization processes, results showed KGE values from 0.5 to 0.8, and a good representation of the runoff seasonality. This is the first time that a monthly streamflow database (PISCO-HyM_GR2M) is developed at national scale in Peru in the 1981-2016 period. This new product will contribute to the hydrological droughts monitoring in Peru and understand water balance on ungauged basins.
3D structures and sedimentary infill across the continent-ocean transition of the northern South China Sea: constraint by the drilling results from IODP Expeditions 367, 368 and 368X
Authors: Lei Chao , Ren Jianye , Mohn Geoffroy , Nirrengarten Michael , Pang Xiong , Zheng Jinyun , Liu Bowen
Published: March 2020

Apart from the Iberia-Newfoundland margins, the South China Sea (SCS) represents  another passive margin where continent-ocean transition basement was sampled by deep drilling. Drilling data from IODP Expedition 367-368 and 368X combined with seismic profiles revealed a narrow continent-ocean transition (COT) between the Distal High sampled at Site U1501 and the Ridge B sampled at Site U1500. Results suggested that major Eocene lithospheric thinning triggered Mid-Ocean Ridge type melt production which emplaced within hyperextended continental crust leading eventually to continental breakup.  

Because of available dense seismic survey consisting of deep-penetrated seismic data imaging as deep as 12 s TWT, as well as drilling results from IODP Expeditions 367-368 and 368X, the COT in the northern SCS enables us to investigate the 3D propagation of continental breakup and the interactions between tectonic extension and magmatism. The top of acoustic basement can be consistently interpreted through all of our seismic survey and reveal various types of reliefs and nature from hyperextended continental crust to oceanic crust. In the basement, deep-penetrated seismic profiles present series of densely sub-parallel high-amplitude reflections that occurred within the lower crust. The lower boundary of these reflections is often characterized by double continual and high reflections interpreted as the Moho. Across the COT, the basement structure is characterized by: 1) Series of tilted blocks bounded by high angle faults on the Distal High and filled by syn-tectonic sedimentary wedges, 2) Rounded mounds of the basement with chaotic seismic reflection and sedimentary onlaps on these structures, 3) Series of ridges delimited by high-angle normal faults with no sedimentary wedge on the first oceanic crust.

Based on the detail stratigraphic framework constraint by drilling results from IODP Expeditions, the nature and timing of formation of these basement highs can be investigated. Some of these highs are limited by extensional faults while the nature of mounded structures located on the thinnest continental crust remain mysterious.  Our detailed analyses emphasize the occurrence and local control of syn-rift magmatism in order to build such structures. At larger scale, the hyperextended continental crust is characterized by significant 3D morphological variations both observed on dip and strike profiles. In contrast, the initial oceanic crust is characterized by a more homogenous structure and consistently juxtaposed to continental crust over a sharp and narrow zone.

 
Can the electrical conductivity of karst spring discharge improve the identification of model structures and reduce simulation uncertainty?
Authors: Chang Yong , Liu Ling , Jiang Guanghui , Hartmann Andreas , Wu Jichun
Published: March 2020

Lumped karst hydrological models often suffer from the over-simplified structures. In recent days, hydrochemical has been used as an auxiliary information to define realistic karst model structures. For karst aquifers, the hydrochemical dynamics of karst springs contain important information about the internal behavior of the karst aquifer that can be conducive to model identification and calibration. In this presentation, electrical conductivity (EC), as a substitution for Ca2+ concentration of the spring discharge, is evaluated for its potential for model structure identification and reduction of simulation uncertainty. A new framework to integrate EC in karst modeling is developed at a small, well-instrumented karst catchment near Guilin City, China. A set of different hydrologic models were enabled to consider the linear dissolution process of Ca2+ and its transport to investigate the models’ abilities to reproduce the behavior of spring discharge and EC. We found that most hydrologic models obtain similar performances concerning spring discharge, however, their performances in simulating spring EC show obvious differences. The combination of observed spring discharge and EC could identify a more realistic model structure that was in accordance with the observed perception of this karst aquifer’s functioning. Using the identified “most realistic” model, we use sensitivity analysis to show that spring EC only improves the identifiability of one hydrologic parameter mostly due to too complex EC dynamics during recharge events and therefore has limited potential to reduce discharge simulation uncertainty. Consequently, our new framework to include EC in karst models opens new doors for more realistic simulation but an explicit treatment of uncertainties remains necessary due to EC’s limited potential to reduce simulation uncertainty. The next step of our work is to integrate appropriate nonlinear dissolution process of carbonate rock in the model to further improve the simulation of spring EC (Ca2+).
Results and subjects about compulsory school education in the Sanin Kaigan, UNESCO Global Geopark, Japan
Authors: Kawamura Norihito
Published: March 2020

In the Geopark, there is a need to foster an interest in the earth and a better understanding of geoscience for young people during educational programs. The ideal method would be to educate this in the classes, in schools to accomplish these goals, but the teachers are unfamiliar with the Geopark in Japan. Recently, some programs have been developed and presented by some teachers in all cities and towns in San’in Kaigan, UNESCO Global Geopark. The author surveyed the data in a real-life situation in educational practices and found some outcomes and subjects about the program. One distinctive outcome is the complete education at the elementary school level. Some subjects are enhancing middle-school level education and the evaluation of the program.

First, the author found good practices in some areas. All elementary school students study at the geo-sites, but junior high school students are presented with lesser opportunities. Second, there is a need for more efficient evaluation functions in the area because improvement methods for educational programs in Japan have not been developed.

There must be authentic educational programs and appropriate evaluation to promote the educational activities for students in the Geopark. In Japan, school teachers are responsible for curriculum design based on the course of study, which includes standard curriculum. They could request local specialists such as guides in the Geopark to teach the students. In such a case, the teachers must evaluate the learning results. However, they might not mark their students’ performances because they do not know the Geopark. Therefore, teacher training programs, focusing on the Geopark, must be promoted.
Foreland basin sediment archives: highlighting their use in documenting deformation of the orogenic hinterland and foreland.
Authors: Najman Yani
Published: March 2020

Interrogation of sediment archives allows for documentation of both hinterland and foreland deformation. Examples of their use as an archive of Himalayan foreland deformation include the work of Govin et al. (Geology, 2018) in which determination of the timing of drainage rerouting of the palaeo-Brahmaputra has allowed us to date the timing of surface uplift of the Shillong Plateau, and the work of Najman et al (Tectonics, 2018) in which the presence of the major Paleogene unconformity previously recognised in the Himalayan foreland basin, was shown to extend much further south into the foreland, allowing for a broader range of possible causal mechanisms to be discussed. There are numerous examples of the use of the Himalayan foreland basin sediment record to determine orogenic tectonics, this being a complementary approach to bedrock studies of the orogen. For example, Govin et al. (in review) and Lang et al (GSAB 2016), used detrital mineral lag time studies targeted to the Siwalik Himalayan foreland sediment archive, to demonstrate when the rapid exhumation of the eastern Himalayan syntaxis commenced. Comparison with a similar dataset derived from a more distal sediment archive of the Bengal Fan (Najman et al. GSAB 2019), shows the advantages (as well as disadvantages) in the use of proximal sediment archives.
Evaluation of the joint effects of DEM resolution and calculation cell size on discharge simulation performance with two routing methods
Authors: Li Jingjing , Chen Hua , Xu Chong-Yu , Zhao Haoyuan , Li Lu , Chen Jie , Guo Shenglian
Published: March 2020

Benefit from the easy access to gridded hydrological datasets and global Digital Elevation Model (DEM) datasets, DEM-based routing methods have been widely developed and used. The routing methods can be divided into two categories, i.e., Source-to-Sink and Cell-to-Cell. Limited by the computation capabilities, routing methods are often performed at more coarse resolution of calculation cell rather than the resolution of DEM. Both the DEM resolution and calculation cell-size are factors that affect the discharge simulation performance of routing method. Too little work has been devoted to how these two factors affect routing performance jointly. This study aims to compare the effects of DEM resolution and calculation cell-size on discharge simulation performance with two most popular routing methods, including a Cell-to-Cell routing method, i.e., Liner-reservoir-routing method (LRR) and a Source-to-Sink routing method, i.e., the improved aggregated network-response function routing method (I-NRF). They are compared/evaluated in terms of the changes of simulation performance with calculation cell-size ranging from 5 arc-minutes to 60 arc-minutes and DEM resolutions of 90 m×90 m, 250 m×250 m, 500 m×500 m, 1000 m×1000 m. Besides, two hydrological runoff-generation models and two study basins are used to test the generality of the result. The study finding will help the researchers to choose the appropriate DEM resolution, calculation cell-size and routing method in hydrological simulation.
Quartz fluid inclusions characteristics of fluvial deposit in Changjiang River and their implications
Authors: Ge Chendong , Ji Zhenqiang
Published: March 2020

The morphological characteristics of quartz inclusions in sediments from five locations in the upper, middle and lower reaches of the Changjiang River are analyzed. The source indication of sediments is discussed through the differences in shape, size, quantity, gas percentage and genetic type. From upstream to downstream, the characteristics of quartz inclusions in sediments are different. The inclusion types appearing in the samples from upstream to estuary are gradually enriched. The sediment influx from the tributaries of the Changjiang River makes new types of quartz inclusions appearing in the downstream and estuary. In terms of quantity and size, most quartz inclusions are concentrated in the range of 2-4 μm in size and 10-150/mm3 in number. The number and size range of different positions are also different. In SGJS-01 collected from Shigu, is 2-18 μm, the number is 2-166 per volume. In YBCJ-01, YZD-63 and YZD-10 samples collected from Yibin, Yichang and Wuhan, the size is 2-15μm, 2-10μm, 2-12μm and the number is 1-270, 2-220 and 1-308 per volume. The primary inclusions of SGJS-01 in Shigu is 14%, higher than that of primary inclusions in the middle and lower reaches, and that of YBCJ-01 in Yibin decreases to 6%, and for YZD-63, YZD-10 and HK-01 they were 8%, 6% and 5% respectively. The change of the primary inclusion proportion reflects the difference of source rock types of sediments. The difference of source rocks of sediments can be reflected in the type, size, quantity and proportion of primary inclusions. The characteristics of quartz inclusions could be a new way to explore the source of sediments.
Constraining the initiation of oceanic subduction of the Proto-Tethys Ocean beneath the Tarim block in northern Gondwana margin
Authors: Yao Jinlong , Zhao Guochun , Han Yigui , Liu Qian , Dong Zengchan , Li Jianhua , Wang Peng , Yu Shan
Published: March 2020

The Proto-Tethys Ocean is principally defined as an ancient ocean distributed to the northern margin of the Gondwana landmasses, which initiated during the breakup of the Rodinia supercontinent and closed in the Early Paleozoic during the final assembly of Gondwana. Major continental blocks of China, including Tarim, Qaidam, South China and North China, were distributed in this ocean. Locally in the Altyn-Tagh UHP belt in the southeastern margin of the Tarim Craton, the ocean is referred to as the Altyn Ocean. The Kulamulake ophiolitic mélange occur within the South Altyn Terrane and was extensively sheared and deformed, with its southern and northern margins of the ophiolitic mélange delineated by a top to the northwest thrusting fault zone and a ductile shearing zone, respectively. The mélange thrust on to the latest Mesoproterozoic-Neoproterozoic Altyn group and Neoproterozoic-Paleozoic Bashikuergan group on its northern and southern margins, respectively. Stratigraphically from bottom to top it is composed of sheared serpentinite on the basal thrust, layered dunite-harzburgite, pyroxene peridotite, layered olivine pyroxenite and fine-grained meta-gabbro, along with exotic blocks of marble. Pillow basalt and plagio-granite have also been reported from within the mélange, which might be upper components of the ophiolite stratigraphy. All the exposed lithostratigraphic sequences occur as structural blocks. Therefore, overall lithologies and structures resembles those of ophiolitic mélanges. Meta-gabbro components of the mélange yield concordia ages of 518 ± 2 Ma, along with juvenile zircon Hf and whole rock isotopic signatures. The analyzed mafic-ultramafic samples display chemical characters that are comparable to E-MORB, but with some island-arc signatures, resembling those of SSZ type ophiolite. In addition, correlations of major and trace element compositions of all analyzed samples are indicative of fractional crystallization from a depleted mantle source. The overall lithological assemblages, isotopes and chemical compositions are consistent with a disrupted ophiolitic mélange during initial oceanic subduction environment. Therefore, we concluded the Kulamulake ophiolite recorded the initiation of oceanic subduction within the Paleo-Tethys Ocean in northern Gondwana margin. This research was supported by NSFC Projects (41730213 and 41190075) and Hong Kong RGC GRF (17307918 and 17301915).
Wood derived biochar as electron donor and its influence on microbial denitrification: Role of extracellular polymeric substances in extracellular electron transfer
Authors: Sathishkumar Kuppusamy , Li Yi , Ikram Rana Muhammad Adnan
Published: March 2020

Biochar is extensively used in environmental pollutant remediation because of its diverse property, however the effect of biochar on microbial nitrate reduction and electrochemical behavior of biochar remain unknown. Also electron transfer from the microbial cells to electron donor or acceptor have been transport across the extracellular polymeric substances (EPS), however it was unclear whether extracellular polymeric substances captured or enhance the electrons.  Hence, aim of the present study is to investigate the electrochemical behavior of biochar and its effects on microbial nitrate reduction and elucidate the role of extracellular polymeric substances in extracellular electron transfer (EET).  The biochar was prepared at different pyrolysis temperatures (400 °C, 500 °C and 600 °C) and their electrochemical behavior was characterized by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectrum, chronoamperometry). Results demonstrated that all the biochars could donate and accept the electrons, impact of biochar on microbial nitrate reduction was studied and the results showed that biochar prepared at 400 °C significantly enhances microbial nitrate reduction process. Phenol O-H and quinone C=O surface functional groups on the biochar contributes in the overall electron exchange which accelerated the nitrate reduction. The role of EPS in EET by electrochemical analysis results reveals that outer membrane c-type cytochrome and flavin protein from the biofilm was involved in electron transfer process, and EPS act as transient media for microbial EET. Overall, present study suggested that biochar could be used as eco-friendly material for the enhancement of microbial denitrification.
Unification of global vertical height system using precise frequency signal links
Authors: Shen Ziyu , Shen Wen-Bin , Zhang Shuangxi
Published: March 2020

The realization of International Height Reference System (IHRS) is one of the major tasks of the International Association of Geodesy (IAG). Here we formulate a framework for connecting two local VHSs using ultra-precise frequency signal transmission links between satellites and ground stations, which is referred to as satellite frequency signal transmission (SFST) approach. The SFST approach can directly determine the geopotential difference between two ground datum stations without location restrictions, and consequently determine the height difference of the two VHSs. Simulation results show that the China’s VHS and the US’s VHS can be unified at the accuracy of several centimeters, provided that the stability of atomic clocks used on board the satellite and on ground datum stations reach the highest level of current technology, about 4.8×10-18 in 100 s. The SFST approach is promising to unify the global vertical height datum in centimeter level in future, providing a new way for the IHRS realization. This study is supported by NSFCs (grant Nos. 41721003, 41631072, 41874023, 41804012, 41429401, 41574007) and Natural Science Foundation of Hubei Province of China (grant No. 2019CFB611).
Deep Neural Networks FOR forest Growing stock volume retrieval: a compartive analysis for L-band SAR data
Authors: Tanase Mihai A. , Belenguer-Plomer Miguel A. , Marin Gheorghe , Badea Ovidiu
Published: March 2020

The aim of this study was to evaluate the utility of deep learning (DL) approaches to estimate forest growing stock volume from L-band SAR data over areas characterized by diverse species composition. For comparison, parametric models were also used. When using one independent variable (i.e. HV backscatter coefficient) the lowest estimation errors were observed for the empirical model followed by Random Forests (RF). Increasing the number of independent variables resulted in marginally more accurate results for the machine learning approaches. However, for the studied area, DL approaches did not improve GSV retrieval when compared to RF or empirical modelling suggesting that L-band data sensitivity to GSV values is the main limiting factor.
Observation of a Terrestrial Electron Beam during the tropical cyclone Joaninha in March 2019
Authors: Sarria David , Kochkin Pavlo , Østgaard Nikolai , Mezentsev Andrew , Lehtinen Nikolai G. , Marisaldi Martino , Maiorana Carolina , Neubert Torsten , Reglero Victor , Carlson Brant E. , Ullaland Kjetil , Yang Shiming , Genov Georgi , Qureshi Bi , Budtz-Jørgensen Ca , Kuvvetli Ir , Christiansen Fr , Chanrion Ol , Navarro-Gonzales Ja , Connell Paul H.
Published: March 2020

Terrestrial Gamma-ray Flashes (TGFs) are short (~20 us to ~2 ms) flashes of high energy (< 40 MeV) photons, produced by thunderstorms When interacting with the atmosphere, the TGF’s photons produce relativistic electrons and positrons at higher altitudes, and a fraction is able to escape the atmosphere [1,2,3]. The electrons/positrons are then bounded to Earth's magnetic field lines and can travel large distances inside the ionosphere and the magnetosphere. This phenomenon is called a Terrestrial Electron Beam (TEB).

The Atmosphere-Space Interactions Monitor (ASIM), dedicated to the study of TGF and associated events, started to operate in June 2018. ASIM contains an optical instrument (MMIA) made of micro-cameras and photometers, as well the Modular X and Gamma-ray Sensor (MXGS) for high energy radiation. MXGS is composed of the low energy detector (LED, 50 keV to 400 keV) and the High Energy detector (HED, 300 keV to 40 MeV). 

This presentation is focused on a new event which was detected on March 24, 2019. The TEB originated from rainbands produced by the tropical cyclone Joaninha, in the Indian Ocean, close to Madagascar. This observation shows, for the first time to our knowledge: (1) the low energy part (>50 keV) of the TEB spectrum, using the LED, (2) an estimate of the incoming direction (to ISS) of the electron Beam from recorded data.

References:

[1] J. R., Dwyer, B. W., Grefenstette and D. M. Smith. High-energy electron beams launched into space by thunderstorms. DOI: 10.1029/2007GL032430. Geophysical Research Letters, 2008.

[2] B. E. Carlson T. Gjesteland N. Østgaard. Terrestrial gamma-ray flash electron beam geometry, fluence, and detection frequency. DOI: 10.1029/2011JA016812. Journal of Geophysical Research (Space Physics), 2011.

[3] D. Sarria, P. Kochkin, N. Østgaard et al. The First Terrestrial Electron Beam Observed by the Atmosphere-Space Interactions Monitor. DOI: 10.1029/2019JA027071. Journal of Geophysical Research (Space Physics), 2019.
Seismic markers of the Messinian salinity crisis in the deep Ionian Basin
Authors: Camerlenghi Angelo , Del Ben Anna , Hübscher Christian , Forlin Edy , Geletti Riccardo , Brancatelli Giuseppe , Micallef Aaron , Saule Marco , Facchin Lorenzo
Published: March 2020

We conduct the seismic signal analysis on vintage and recently collected multichannel seismic reflection profiles from the Ionian Basin to characterize the deep basin Messinian evaporites. These evaporites were deposited in deep and marginal Mediterranean sedimentary basins as a consequence of the “salinity crisis” between 5.97 and 5.33 Ma, a basin‐wide oceanographic and ecological crisis whose origin remains poorly understood. The seismic markers of the Messinian evaporites in the deep Mediterranean basins can be divided in two end‐members, one of which is the typical “trilogy” of gypsum and clastics (Lower Unit – LU), halite (Mobile Unit – MU) and upper anhydrite and marl layers (Upper Unit – UU) traced in the Western Mediterranean Basins. The other end‐member is a single MU unit subdivided in seven sub‐units by clastic interlayers located in the Levant Basin. The causes of these different seismic expressions of the Messinian salinity crisis (MSC) appear to be related to a morphological separation between the two basins by the structural regional sill of the Sicily Channel. With the aid of velocity analyses and seismic imaging via prestack migration in time and depth domains, we define for the first time the seismic signature of the Messinian evaporites in the deep Ionian Basin, which differs from the known end‐members. In addition, we identify different evaporitic depositional settings suggesting a laterally discontinuous deposition. With the information gathered we quantify the volume of evaporitic deposits in the deep Ionian Basin as 500,000 km3 Å} 10%. This figure allows us to speculate that the total volume of salts in the Mediterranean basin is larger than commonly assumed. Different depositional units in the Ionian Basin suggest that during the MSC it was separated from the Western Mediterranean by physical thresholds, from the Po Plain/Northern Adriatic Basin, and the Levant Basin, likely reflecting different hydrological and climatic conditions. Finally, the evidence of erosional surfaces and V‐shaped valleys at the top of the MSC unit, together with sharp evaporites pinch out on evaporite‐free pre‐ Messinian structural highs, suggest an extreme Messinian Stage 3 base level draw down in the Ionian Basin. Such evidence should be carefully evaluated in the light of Messinian and post‐Messinian vertical crustal movements in the area. The results of this study demonstrates the importance of extracting from seismic data the Messinian paleotopography, the paleomorphology and the detailed stratal architecture in the in order to advance in the understanding of the deep basins Messinian depositional environments.
Concerning the impact of deorbiting spacecraft to the upper atmosphere
Authors: Schulz Leonard , Glassmeier Karl-Heinz
Published: March 2020

The increasing activities in space due to more and more countries with space programs, advancing commercialization, and large satellite constellation projects lead to a rising number of human-made objects in space. While many of those stay in orbit at high altitudes, objects in low Earth orbit reenter the atmosphere mostly disintegrating and injecting material into the atmosphere. The growing concern about space debris has led to policies encouraging deorbiting of satellites at the end of their lifetime. All that will increase the annual mass influx into the atmosphere by human-made (anthropogenic) objects in the future. We compare the influx of those objects to the natural mass influx of entering meteoroids of asteroidal, cometary, and planetary origin into Earth's atmosphere. We look at the mass and the elemental composition of the entering bodies also incorporating different ablation of those objects. This way, a quantitative assessment of the annual injection of aerosols and atomic remnants into the atmosphere is possible. Today, anthropogenic material makes up way less than 1 % of the overall injected mass. However, future large spacecraft constellations could increase the anthropogenic influx significantly, then contributing 4 % or more of the whole injection. As spacecraft have a high abundance of metal elements, the metal mass portion of the injection can reach up to 15 %. For some elements, the anthropogenic injection may even prevail the natural injection. This implies for future large satellite constellations that the anthropogenic injection can become significant with unknown effects on the upper atmosphere and the terrestrial habitat.
Using “Selfie drones” for 3D mapping of volcano-tectonic features in Santorini, Greece
Authors: Antoniou Varvara , Nomikou Paraskevi , Vlasopoulos Othonas
Published: March 2020

Generally, key geological outcrops are inaccessible for classical mapping due to the hard-logistic conditions of their location in remote or dangerous areas like active volcanoes or fault zones. The UAV-based photogrammetry is a helpful technique to overcome such difficulties in site investigation. It allows a very high-detailed 3D model reconstruction of relevant outcrops, providing also the possibility to cover wider areas.

In this study, we tested the use of a “Selfie drone” aimed at outcrops reconstruction for 3D mapping of volcano-tectonic features. Two different sites in Santorini volcanic complex with different characteristics have been chosen: i) the Vlychada Beach, located in the southern part of the island, characterized by vertical cliffs that offer great exposure of the pumice layers from the well-known Late Bronze Age (LBA) (Minoan) eruption and ii) a historical volcanic crater located in the northern part of Nea Kameni island, related to the 1570 A.D. eruption, with a diameter of about 85 m, which is mostly inaccessible within its internal part and cannot be studied by classical field methods. 

The “Selfie drone” which was used for the photo collection, is a 0.300-kg quadcopter equipped with a 12 Megapixel camera, EXIF information (Exchangeable Image File Format) and GPS coordinates. This drone has a flight time of approximately 16 minutes. A total of about 1900 photos has been collected, considering both sites, that have been reconstructed using photogrammetry techniques.

The resulting 3D models are characterized by a sub-centimetric texture resolution, allowing detailed mapping of the Minoan pumice layers, fractures, crater geometry, and related volcanic deposits, proving the usefulness of “Selfie drones” for geological – tectonic mapping.
High-resolution mapping of NOx emissions from the Canadian Oil Sands from TROPOMI
Authors: McLinden Chris , Fioletov Vitali , Griffin Debora , Dammers Enrico
Published: March 2020

Direct estimates of air pollution emissions using a combination of satellite observations and meteorological reanalyses are becoming increasingly advanced and widely used. In this presentation, a new such methodology, able to resolve NOx emissions from multiple, adjacent emissions sites of varying sizes, but still applicable over larger scales, is presented. This method was applied to TROPOMI NO2 observations over the entirety of the Canadian oil sands, deriving emissions from small-to-large surface and in-situ mining operations. Initial comparisons with best available bottom-up emissions estimates show good consistency, and that TROPOMI is able to discern NOx emissions at the 1 kt[NO2]/yr level.
Interstellar Heliosphere Probes （IHPs）
Authors: Zong Qiugang
Published: March 2020

Supersonic solar wind streams away from the Sun in all directions, interaction with the local interstellar medium to form a giant plasma bubble, which is coined by A. J. Dessler as “heliosphere”. Voyager 1& 2 spacecraft have recently encountered the heliospheric boundaries of this plasma bubble, e.g. the termination shock, heliosheath and heliopause.

To explore further on the dynamics on the heliospheric boundaries, even the hydrogen wall, and the local interstellar medium,  an Interstellar Heliosphere Probes （IHPs）mission have been proposed to Chinese national space agency (two spacecraft, one towards the nose of the heliopause, one opposite). The plan is that the spacecraft is to reach 100AU when it is 100th anniversary of the PR China (2049). Thus, IHP will allow us to discover, explore, and understand fundamental astrophysical processes in the largest plasma laboratory-- the heliosphere.
Greenhouse climate forces expansion of peatlands into inland areas
Authors: Zhang Zhihui , Wang Chengshan , Lv Dawei , Wang Tiantian
Published: March 2020

As a significant terrestrial carbon reservoir, peatland has great potential to affect the global carbon cycle and global climate. However, our understanding of broad-scale mechanisms that control the long-term global peatland expansion and carbon accumulation rates is still limited. Here we present a new data synthesis of global coal deposit location, thickness changes, carbon concentration, and distribution area changes, along with new carbon pool estimates of global peatlands from Devonian through geological time. By identifying orbital cycles in coal seams, we show that the long-term rate of carbon accumulation (LORCA) in peatland calculated from published data is controlled by pO2, pCO2, temperature, precipitation, and total solar irradiance. We use this relationship and latitudinal temperature gradients to reconstruct the equations between LORCA with latitude on different geological time. The results suggest that there are three main sets of high carbon pool and high carbon accumulation rate of global peatlands in Late Paleozoic, Early-Middle Jurassic, and Late-Cretaceous to Early Cenozoic under low tectonic activity and high terrestrial plant diversity background. In addition, we measure the shortest distances between all coal locations and coastlines based on the new Scotese’s paleo-Atlas for the past 400 million years, in order to exhibit the extent of peatland expansion into inland. The result shows the Early-Middle Jurassic period has the longest average distance, which is probably due to the high sea level that minimizes the development of peat swamps on coastal areas and facilitated the moisture to move into deeper inland under the Jurassic Greenhouse climate condition. This study highlights that combining comprehensive coal-related database with paleoclimate, tectonics, and evolution of land plants provides insights into the mechanisms of the long-term behavior of the peatland expansion and carbon reservoir through deep time.

Keywords: Greenhouse climate, Peatland expansion, Carbon pool, Cabon accumulation rates, Coal

This study wasfinancially supported by the National Natural Science Foundation of China (grant No. 41888101), the National Key R&D Plan of China (grant No. 2017YFC0601405) and the National Natural Science Foundation of China (grants 41790450, 41772096).
Where is the Toba eruption in the Vostok ice core? Clues from tephra, O and S isotopes
Authors: Savarino Joel , Gautier Elsa , Caillon Nicolas , Albalat Emmanuelle , Albarède Francis , Hattori Shohei , Petit Jean-Robert , Lipenkov Vladimir
Published: March 2020

The ca. 74 ka BP ‘‘super-eruption’’ of Toba volcano in Sumatra is the largest known Quaternary eruption. It expelled an estimated of 2800 km3 of dense rock equivalent, creating a caldera of 100 x 30 km. The eruption is estimated to have been 3500 greater than the Tambora eruption that created the “year without summer” in 1816 in Europe (Oppenheimer, 2002). However, the consequences of this “mega-eruption” on the climate and human evolution that could be expected for such eruption are still debated and uncertain. There is no evidence that this eruption has triggered any catastrophic climate change such as a “nuclear winter”. One of such lack of evidence lies in the ice.

In the ice core community, this eruption still remains a mystery. Indeed, the estimated size of the eruption should have left a gigantic mark in the ice, at least in the form of a huge sulfuric acid layer but none of the ice records covering this period show any such singularity. The sulfate record seems so common that it is in fact difficult to allocate a specific sulfate peak to this event.

In an effort to synchronize the Vostok ice core and the EPICA Dome C core, (Svensson et al., 2013) have identified three possible sulfuric acid layers for the Toba eruption in the Vostok ice core. In order to see if one of such event could have been the Toba eruption, we have performed the sulfur  & oxygen isotope analysis of these three sulfuric acid layers in the hope that it could reveal some particularity. The sulfur results show that 1- all these three events have injected their products in the stratosphere and 2- the sulfur isotopic compositions of these three events share a common array, array that is in lines with other stratospheric eruptions, however one of the three acid layers shows an extremely and unusual weak oxygen anomaly, potentially indicating a major eruption. In order to remove the last doubts about the existence or not of one or a series of eruptions related to TOBA, the geochemical analysis of volcanic glasses trapped in the ice will be performed and presented.
The key forms of Chromium influencing the long-term stability of Cr in Cr-contaminated soils and chemical stabilized soils
Authors: Li Danni , Li Guanghe , Zhang Dayi
Published: March 2020

The toxicity and persistence of chromium in soils challenge the ecosystem and human health. Various remediation strategies have been developed to eliminate soil Cr contamination, and the most popular one is chemical stabilization. However, chemical stabilization only changes the form of Cr and does not change the concentration of Cr, so the long-term stability of Cr has been controversial. On the other hand, some researches found that the concentration of Cr(VI) in the stabilized soil after remediation has increased. We collected Cr-contaminated soils and one-year-stabilized soils from four research sites in northern, central, and southwestern China, trying to understand the difference of Cr species and structure in soils with various soil properties. Results showed despite the different clay content and mineral composition, all contaminated and stabilized soils are alkaline (pH 7.36 ~ 10.5). In addition, there are differences in the pollution levels of Cr and Cr (VI) in soils. In northern China, Cr(VI) was the main state of Cr-contaminated soils; however, Cr is mainly present in Cr-contaminated soil in the form of Cr(III) in southern China. For chemical stabilized soils, Cr concentrations remained similar to Cr-contaminated soils (1500~9000 mg/kg), but the concentration of Cr(VI) (5~55 mg/kg) was reduced through commercial remediation materials. The speciation of Cr in Cr-contaminated soils transformed from exchangeable Cr and Cr bound to carbonates into Cr bound to Fe-oxides and residuals in stabilized soils. SEM-EDS, XAFS and μ-XRF results revealed the main forms and structure of Cr, and showed Cr unevenly distributed on the surface or edge of the mineral. The acid leaching test revealed that Cr(VI) could be released from Cr-contaminated soils by acid, and soils can release Cr(VI) under different acidity conditions. Cr(VI) from soils collected from northern and southern China was released from acidity of [H+]=0.1M and [H+]=0.5M, respectively. This was due to erosion of coating minerals or Cr(VI)-bearing minerals. Our study suggested that stabilization technology not only reduces the toxicity of chromium, improves the stability of chromium, but also partially recovers the physical and chemical properties of soil. Meanwhile, in future remediation projects, it is necessary to consider the existing forms of chromium in different soils to develop remediation strategies.