bluuebunny/crossref_metadata_2025 huggingface dataset:
High-resolution glacial lake outburst flood impact evaluation using high-performance hydrodynamic modelling and open-source data
Authors: Chen Huili , Liang Qiuhua , Zhao Jiaheng , Xia Xilin
Published: March 2020

Glacial lake outburst floods (GLOFs) are one of the major natural hazards in certain populated mountainous areas, e.g. the Himalayan region, which may lead to catastrophic consequences including fatalities. Evaluating the potential socio-economic impact of GLOFs is essential for mitigating the risk of GLOFs and enhancing community resilience. Yet in most of the cases, the impact evaluation of potential GLOFs is confronted with limited data availability and inaccessibility to most of the glacial lakes in the high-altitude areas. This study aims to exploit recent advances in Earth Observation (EO), open-source data from different sources, and high-performance hydrodynamic modelling to innovate an approach for GLOF risk and impact assessment. GLOF scenarios of different glacier dam breach width and depth are designed according to high-resolution aerial imagery and terrain data acquired from unmanned aerial vehicle surveying. High-performance hydrodynamic model supported by open-source multi-resolution data from the latest EO technologies is used to simulate the flood hydrodynamics to provide spatial and temporal flood characteristics. Detailed information on communities and infrastructure systems is collected and processed from multiple sources including OpenStreetMap, Google Earth, and global data products to support impact analysis. The evaluation framework is applied to Tsho Rolpa glacial lake in Nepal, which has been identified as one of the potentially dangerous glacial lakes that may create GLOFs to threaten the downstream communities and infrastructure. According to the simulation results, the worst GLOF scenario can potentially inundate 27 villages, 583 buildings and 20.8 km2 of agricultural areas, and pose high risk to 1 airport, 1 hydro power plant, 3 bus stations, and 21 bridges. Additionally, the spatial and temporal flood simulation results, including water depth, flow velocity and flood arrival time may help identify impacted sites and objects, which would be valuable for the development of evacuation plans and early warning systems.
Reduced-Order Flood Modeling Using Uncertainty-Aware Deep Neural Networks
Authors: Jacquier Pierre , Abdedou Azzedine , Soulaïmani Azzeddine
Published: March 2020

Key Words: Uncertainty Quantification, Deep Learning, Space-Time POD, Flood Modeling

While impressive results have been achieved in the well-known fields where Deep Learning allowed for breakthroughs such as computer vision, language modeling, or content generation [1], its impact on different, older fields is still vastly unexplored. In computational fluid dynamics and especially in Flood Modeling, many phenomena are very high-dimensional, and predictions require the use of finite element or volume methods, which can be, while very robust and tested, computational-heavy and may not prove useful in the context of real-time predictions. This led to various attempts at developing Reduced-Order Modeling techniques, both intrusive and non-intrusive. One late relevant addition was a combination of Proper Orthogonal Decomposition with Deep Neural Networks (POD-NN) [2]. Yet, to our knowledge, in this example and more generally in the field, little work has been conducted on quantifying uncertainties through the surrogate model.
In this work, we aim at comparing different novel methods addressing uncertainty quantification in reduced-order models, pushing forward the POD-NN concept with ensembles, latent-variable models, as well as encoder-decoder models. These are tested on benchmark problems, and then applied to a real-life application: flooding predictions in the Mille-Iles river in Laval, QC, Canada.
For the flood modeling application, our setup involves a set of input parameters resulting from onsite measures. High-fidelity solutions are then generated using our own finite-volume code CuteFlow, which is solving the highly nonlinear Shallow Water Equations. The goal is then to build a non-intrusive surrogate model, that’s able to know what it knows, and more importantly, know when it doesn’t, which is still an open research area as far as neural networks are concerned [3].

REFERENCES
[1] C. Szegedy, S. Ioffe, V. Vanhoucke, and A. A. Alemi, “Inception-v4, inception-resnet and the impact of residual connections on learning”, in Thirty-First AAAI Conference on Artificial Intelligence, 2017.
[2] Q. Wang, J. S. Hesthaven, and D. Ray, “Non-intrusive reduced order modeling of unsteady flows using artificial neural networks with application to a combustion problem”, Journal of Computational Physics, vol. 384, pp. 289–307, May 2019.
[3] B. Lakshminarayanan, A. Pritzel, and C. Blundell, “Simple and scalable predictive uncertainty estimation using deep ensembles”, in Advances in Neural Information Processing Systems, 2017, pp. 6402–6413.
Evaluation of pipeline corrosion rates due to enhanced telluric activity associated with space weather
Authors: Trichtchenko Larisa
Published: March 2020

Telluric currents are the natural phenomena especially pronounced in the high latitude areas (above 60 degrees). These currents, as any stray current, are able to interfere with pipeline cathodic protection systems, and came into wide consideration with construction of pipelines in northern areas, where the geomagnetic variations are more severe and last for prolonged times.

The paper will explain the approach developed for estimation of pipeline corrosion rates due to telluric activity, and results of its applications.

Statistical evaluation of the occurrence rates for the pipe-to-soil potential difference values based on modelling of the pipeline response to the geomagnetic activity in two different locations (high latitude and mid-latitude) will be combined with the method developed for calculation of corrosion rate (metal loss). The presented approach and results of its application to different types of pipelines located at different latitudes can be used as a practical guidance for the assessments of the space weather impacts on pipeline operations.
Recovering climate-related mass transport signals by current and next-generation gravity missions
Authors: Pail Roland , Dobslaw Henryk , Eicker Annette , Jensen Laura
Published: March 2020

Gravity field missions are a unique geodetic measuring system to directly observe mass transport processes in the Earth system. Past and current gravity missions such as CHAMP, GRACE, GOCE and GRACE-Follow On have improved our understanding of large-scale mass changes, such as the global water cycle, melting of continental ice sheets and mountain glaciers, changes in ocean mass that are closely related to the mass-related component of sea level rise, which are subtle indicators of climate change, on global to regional scale. Therefore, mass transport observations are also very valuable for long-term climate applications. Next Generation Gravity Missions (NGGMs) expected to be launched in the midterm future have set high anticipations for an enhanced monitoring of mass transport in the Earth system with significantly improved spatial and temporal resolution and accuracy. This contribution will present results from numerical satellite mission performance simulations designed to evaluate the usefulness of gravity field missions operating over several decades for climate-related applications. The study is based on modelled of mass transport time series obtained from future climate projections until the year 2100 following the representative emission pathway RCP8.5 Numerical closed-loop simulations will assess the recoverability of mass variability signals by means of different NGGM concepts, e.g. GRACE-type in-line single-pair missions, Bender double-pair mission being composed of a polar and an inclined satellite pair, or high-precision high-low tracking missions following the MOBILE concept, assuming realistic noise levels for the key payload. In the evaluation and interpretation of the results, special emphasis shall be given to the identification of (natural or anthropogenic) climate change signals in dependence of the length of the measurement time series, and the quantification of robustness of derived trends and systematic changes.
ANDES: The first system for flash flood monitoring and forecasting in Peru
Authors: Waldo Lavado-Casimiro , Juan Carlos Jimenez , Harold Llauca , Karen Leon , Clara Oria , Alan Llacza , Adrian Huerta , Oscar Felipe , Julia Acuña , Pedro Rau , Jorge Abad
Published: March 2020

Hydrological hazards related to flash floods (FF) in Peru have caused many economic and human life losses in recent years. In this context, developing complete early warning systems against FF is necessary to cope impacts. For this purpose, hydrological and hydraulic models coupled to numerical weather models (NWM) that provide forecasts are generally used.

In this sense, the National Meteorological and Hydrological Service of Peru (SENAMHI) has launched the ANDES initiative (Operational Forecasting System for Flash Floods of SENAMHI in English) to support FF events. 

The pilot region is the Vilcanota basin located in the southern Andes into Cusco department. For this purpose, 4 hydrological stations will be monitoring at hourly time resolution (km 105-Intihuatana, Chilca, Pisac and Sallca). More, 3 video cameras in real time will be employed to velocimetry and water levels monitoring. An exhaustive hydrometry analysis (rating curve) will be implemented to follow discharges day by day. The forcing for the hourly hydrological modelling will be the SENAMHI’s automatic stations (rainfall and temperature). For this purpose a merge spatial prediction methodology between satellite real time precipitation and gauge station precipitation will be develop: GPM (Imerg), GSMAP and Hydroestimator satellite products will be evaluated. Preliminary results of hourly hydrological model shown good results using pure satellite precipitation. In the next months an hydraulic model will be implemented in the channels with more flood vulnerability (Lisflood model) that together with an Numerical weather prediction (NWP) the WRF (The Weather Research and Forecasting) meteorological model will be implemented in the Vilcanota basin. The update will be done every six hours and to improve the output results a bias correction methodology  will be use. Finally using these forecasts will be assimilated in the hydrological and hydraulic models.

This research is part of the multidisciplinary collaboration between British and Peruvian scientists (NERC, CONCYTEC).
Apocalypse then? The Laacher See eruption (13ka BP) and its human impact along a proximal-to-distal transect
Authors: Riede Felix
Published: March 2020

Approximately 13,000 years BP, the Laacher See volcano, located in present-day western Germany (East Eifel volcanic field, Rhenish Shield) erupted cataclysmically. Airfall tephra covered Europe from the Alps to the Baltic. As part of an on-going project investigating the potential ecological and human impacts of this eruption, legacy data harvested from a variety of disciplinary sources (palynology, pedology, archaeology, geological grey literature) is now combined with recent geoarchaeological work, to provide new insights into the distribution of the Laacher See fallout and its impact on contemporaneous hunter-gatherer populations. This detailed reconstruction of human impact 13,000 years ago also forms the basis for reflection on modern strategies for coping with the emerging risks posed by extreme and compound events in the present and near future.
Increasing Frequency of Flood Events across the Central United States: A Weather-Type Perspective
Authors: Villarini Gabriele , Zhang Wei
Published: March 2020

The frequency of flood events has been increasing across large areas of the central United States since the second half of the 20th century; these increasing trends have been largely related to changes in precipitation. The aim of this presentation is to provide insights into the possible reasons responsible for these changes, providing basic information that may enhance our capability of predicting and projecting these changes.

This study highlights the role of weather types in explaining the observed changes in precipitation and, consequently, in the frequency of flood events. More specifically, we identify five weather types from daily 500-hPa geopotential height using the k-means cluster analysis. Consistent with their distinct large-scale atmospheric patterns, these weather types exert different effects on precipitation in the central United States. Because of the strong moisture transport, strengthened low-level jet stream and wavy upper-level polar jet stream located in the western United States, among the five weather types weather-type 1 exerts the strongest impacts on precipitation, accounting for up to 40% of the total precipitation over the study region. Moreover, we detect a significant upward trend in the number and persistency of these two weather types for 1948–2019, suggesting a rising risk of heavy and long-lasting precipitation across the central United States.
On the sensitivity of 21st century spring plant phenology projections to the choice of statistical downscaling method
Authors: Dixon Keith , Adams-Smith Dennis , Lanzante John
Published: March 2020

We examine several springtime plant phenology indices calculated from a set of statistically downscaled daily minimum and maximum temperature projections. Multiple statistical downscaling methods are used to refine daily temperature projections from multiple global climate models (GCMs) run with multiple radiative forcing scenarios. Focusing on the northeastern United States, the statistically downscaled temperature projections are input to a commonly used Extended Spring Indices (SI-x) model, yielding yearly estimates of phenological indices such as First Leaf Date (an early spring indicator), First Bloom Date (a late spring indicator), and the occurrence of Late False Springs (a year in which a hard freeze occurs after first bloom, when plants are vulnerable to damage from freezing conditions). The matrix of results allows one to analyze how projected spring phenological index differences arising from the choice of statistical downscaling method (i.e., the statistical downscaling uncertainty) compare with the magnitudes of variations across the different GCMs (climate model uncertainty) and radiative forcing pathways (scenario uncertainty). As expected, the onset of spring in the late 21st century projections, as measured by First Leaf and First Bloom Dates, typically shifts multiple weeks earlier in the year compared with the historical period. Those two start-of-spring indices can be thought of as being largely, but not entirely, dependent on an accumulation of heat since 1 January. In contrast, a Late False Spring occurs in large part due to a short-term weather event - namely if any single day after the First Bloom Date has a minimum temperature below -2.2C. Accordingly, spring phenological indices calculated from statistically downscaled climate projections can be influenced by how well the GCM’s historical simulation represents temperature variations on different time scales (diurnal temperature range, synoptic time-scale temperature variability, inter-annual temperature variations) as well as how a particular statistical refinement method (e.g., a delta change factor method, a quantile-based bias correction method, or a constructed analog method) combines information gleaned from both the GCM time series and the observation-based training data to generate the statistically refined daily maximum and minimum temperature time series. Though this study is limited in scope (northeastern United States region, a finite set of statistical downscaling methods and GCMs), we believe the general findings likely are illustrative and applicable to a wider range of mid-latitude locations where plant responses in spring are mostly temperature and day length driven.
Structural Transition of Trimethylamine Hydrate by Methane or Hydrogen Inclusion
Authors: Cha Minjun
Published: March 2020

Recently, several alkylamine hydrates have been studied in an effort to reveal the structural transitions from semi- to ‘canonical’ clathrate hydrate in the presence of secondary guest molecules. Trimethylamine (TMA) is known to form the semi-clathrate hydrate, and it has been reported that the structural transition of the TMA semi-clathrate hydrate may not occur in the presence of hydrogen gas as a secondary guest molecule. This paper reports the structural transition of trimethylamine(TMA) hydrate induced by the type of guest molecules. Powder X-ray diffraction patterns of (TMA + H2) hydrates show the formation of hexagoanl P6/mmm hydrate, but those of (TMA + CH4) hydrates indicate the formation of cubic Fd3m hydrate. Without gaseous guest molecule, the crystal structure of pure TMA hydrate is identified as hexagonal P6/mmm. Therefore, inclusion of gaseous methane in TMA hydrate can induce the structural transition from hexagonal to cubic hydrate or the formation of metastable cubic hydrate. To clearly reveal this possibility, we also check the time-dependent structural patterns of binary (TMA + CH4) hydrates from 1 to 14 days, and the results show that the structural transition of TMA hydrate from hexagonal P6/mmm to cubic Fd3m hydrate structure can occur during the methane inclusion process.
The nighttime poleward wind responses to SAPS simulated by TIEGCM: a universal time effect
Authors: Zhang Kedeng , Wang Hui , Wang Wenbin , Liu Jing , Zhang Shunrong , Sheng Cheng
Published: March 2020

The present work investigates the nighttime meridional wind (30º-50º magnetic latitude and 19-22 magnetic local time) in response to subauroral polarization streams (SAPS) that commence at different universal time (UT) by using Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) under geomagnetically disturbed conditions that are closely related to the southward interplanetary magnetic field (IMF) carried by the solar wind. The SAPS effects on the meridional winds show a remarkable UT variation, with larger magnitudes at 00 and 12 UT than at 06 and 18 UT. The strongest poleward wind emerges when SAPS commence at 06 UT, and the weakest poleward wind develops when SAPS occur at 00 UT. A diagnostic analysis of model results shows that the pressure gradient is more prominent for the developing of the poleward wind at 00 and 12 UT. Meanwhile, the effect of the ion drag is important in the modulation of the poleward wind velocity at 06 and 18 UT. This is caused by the misalignment of the geomagnetic and geographic coordinate systems, resulting to a large component of ion drag in geographically northward (southward) direction due to the SAPS channel orientation at 06 and 18 UT (00 and 12 UT). The Coriolis force effect induced by westward winds maximizes (minimizes) when SAPS commence at 12 UT (00 UT). The centrifugal force due to the accelerated westward winds shows similar UT variations as the Coriolis force, but with an opposite effect.
Spatiotemporal distribution of major pollutants and their health impacts in Hubei Province from 2015 to 2018 based on machine learning to improve LUR
Authors: Feng Xiao
Published: March 2020

Air pollution poses a serious threat to human health. A large number of studies have shown that certain diseases are closely related to air pollution. Understanding the spatiotemporal distribution of air pollutants and their health effects are of great significance for pollution prevention. This study takes Hubei Province, China as an example. It integrates measured ground air quality data, natural environment data, and socioeconomic data, and uses machine learning to improve the land use regression model to simulate the spatial distribution of concentration PM2.5 / O3 from 2015 to 2018 in the study area. The combined pollutant concentration data and population raster data were used to assess the deaths from specific diseases (stroke, ischemic heart disease, lung cancer) caused by air pollutants. The result shows that high concentrations of pollutants are concentrated in the more economically developed eastern regions of Hubei Province, and the economically backward western regions have good air quality. In addition, the distribution of deaths caused by exposure to air pollution is similar to that of pollutants, which is higher in eastern part of Hubei province. However, the total number of deaths in the province is decreasing year by year. This result shows that environmental governance policies have alleviated the threat of air pollution to human health to some extent. It shows that Hubei Province should combine actual conditions and spatial-temporal distribution characteristics of pollutants to make appropriate environmental protection measures.
Quantification of Nitrogen in Food Chain Wastes in Jiangsu Province and Its Environmental Effects
Authors: Zhang Yajuan
Published: March 2020

 Nitrogen is an indispensable nutrient for the growth of plants and animals. It is also one of the key elements controlling the structure and function of terrestrial, freshwater and marine ecosystems. The study of the nitrogen amount in the food chain system “crop-livestock-household” could safeguard human health and lay the foundation for food production. In this paper, we focused on Jiangsu Province county in the lower reaches of the Yangtze River as the research target area. The material flow analysis and mass balance method combined with field research were used to construct a food chain production-consumption nitrogen flow model, for analyzing quantitatively the nitrogen in the crop-livestock-household system. During 2000~2016, the total inputs of nitrogen in the food chain of Jiangsu Province area decreased from 3.38×106 t N yr-1 to 3.15×106 t N yr-1. The crop production subsystem has become the main nitrogen input source in the food chain (77.84%). This may be caused by the ever-increasing urbanization rate and the shrinkage of farmland.

Compared with 2000, the amount of waste nitrogen produced by the “crop-livestock-household” system in 2016 decreased by 31.17%. During this period, the poultry breeding subsystem contributed dominantly to the total waste nitrogen, which was 36.84%, followed by the household consumption subsystem of 35.90%, and 27.25% from the crop production subsystem. The waste nitrogen is mainly recycled through returning to the field and as feed. The nitrogen circulation rate is low (18.46~21.85%). The main sources of environmental nitrogen load include chemical fertilizer application, manure, straw and kitchen waste. The waste nitrogen utilization may recycle effectively the resources, and conform to the concept of building a resource-saving and environment-friendly society. The measures are benefits for sustainable development in society.
Holocene megaflood history and provenance of the upper Indus-River. Implication for human migration along the ancient Silk Road at Ladakh.
Authors: Pankaj Sharma Choudhurimayum , Chahal Poonam , Kumar Anil , Srivastava Pradeep , Singhal Saurabh , Agnihotri Rajesh , Wasson Robert J , Ziegler Alan D , Shukla Uma Kant
Published: March 2020

          The Indus River originating from the Manasarovar Lake runs along the Indus Tsangpo Suture Zone at Ladakh separating the Tethyan Himalaya in the south from the Karakoram Zone in the north. Due to the barrier created by the Pir Panjal Ranges and the Higher Himalaya, Ladakh falls in the rain shadow zone of ISM (Indian Summer Monsoon) with an average annual temperature of ~7.3°C. Random catastrophic hydrological events are known to endanger lives and properties of people residing here. So, determination of frequency, recurrence and forcing mechanism of past extreme floods are crucial in this highly vulnerable area.

          Here we studied Holocene mega flood history of the Upper Indus River at Ladakh using slack water deposits (SWDs). SWDs are composed of stacks of sand-silt couplets deposited during high flooding events. They are deposited instantly from suspension associated with sharp reduction of flow velocity due to local obstructions. Each couplet represent a flooding event. These events are dated employing Optically Stimulated Luminescence (OSL) using sand and AMS 14C using charcoal specks and hearth layers. The frequency of these events suggest higher occurrence of mega floods during pronounced northward penetration of ISM. Recurrence Interval (RI) analysis of these events suggest spatial variation in forcing mechanism between the trunk and the main tributary channel (Zanskar). Sedimentary provenance of these events are also analyzed using detrital zircon geochronology. The provenance analysis indicate more efficient sediment transportation along the Zanskar River as compared to the main Indus channel. Post LGM (Last Glacial Maximum) human migration along the channel is revealed from hearths found within these SWDs which generally occurs during post flooding episodes. Materials found within the hearths, chronology and the fashion of occurrence imply migration and cultural connectivity between the Indian sub-continent and the Central Asia along the ancient Silk Road at Ladakh as old as ~14 ka.
Application of geomorphological mapping and fingerprinting to identify the different suspended sediment sources of the glaciated Djankuat catchment, Caucasus mountains
Authors: Tsyplenkov Anatoly , Kharchenko Sergey , Vanmaercke Matthias , Golosov Valentin
Published: March 2020

Suspended sediment yield values from glaciated mountain catchments are often among the highest in the world. Nonetheless, the sediment sinks, sources and dynamics can be highly variable in such environments under climate change. The aim of this study is to quantify the different suspended sediment sources of the Djankuat river catchment (A=9,1 km2). This small high mountain stream is located in the Caucasus mountains. It is partly glaciated with steep slopes, alpine meadows and glacial-nival terrains. Large scale geomorphological mapping of the catchment was undertaken using drone images and field surveys. This allowed to identify the main sediment sources as well as key pathways of the sediment to the river. In addition, about 50 composite surface (topsoil) and subsurface (riverbanks) samples were collected within the catchment area to characterize the different sediment sources. Two different mixing models (fingerPRO and SIFT) were applied to evaluate the relative contribution of these sources to river suspended sediment yield. Furthermore, direct measurements of water discharge and turbidity were undertaken at two gauging stations. One of them was located near the edge of glacier and the other about 1 km downstream. This allowed to evaluate the relative contribution of the glacial and proglacial part of the catchment to the total suspended sediment yield. Overall, these independent approaches resulted in relatively similar estimates of the relative importance of the different sources to suspended sediment yield. It has been established that the proportion of glacial material (generated by glacier erosion, including subsurface and supraglacial runoff) in total suspended sediment load decreases from 80-90% at the first 50-100 m from the glacier edge to 60-70% at a distance of 700-1000 m.

This study was funded by the Russian Science Foundation, project no. 19-17-00181
Sediment transport modelling of the Drava River confluence
Authors: Cikojević Antonija , Gilja Gordon , Baranya Sándor , Kuspilić Neven , Pomázi Flóra
Published: March 2020

Drava River confluence is characterized by specific morphodynamic processes under which significant sediment deposition is occurring at the Drava River mouth, impeding fairway conditions. Morphodynamic analysis requires long-term hydraulic and sediment transport regime data as input for estimation of equilibrium conditions, taking into account baseline conditions of both rivers. This paper presents results of detail investigations of morphodynamic changes at the Drava River confluence during the 2-year period. Quantification of morphodynamic processes is conducted indirectly through interpretation of ADCP transects surveyed over wider confluence zone, estimation of sediment transport intensity and bathymetric surveys. Purpose of the conducted analysis was to estimate morphodynamic development of the riverbed based on the 1D numerical model results. Numerical model is calibrated using flow velocity field and sediment transport pattern for range of hydrological events. Validation of sediment transport method is done through comparison of morphological changes on characteristic profiles between two consecutive surveys.
Numerical Weather Forecast Post-processing with Ensemble Learning and Transfer Learning
Authors: Chen Yuwen , Huang Xiaomeng
Published: March 2020

Statistical approaches have been used for decades to augment and interpret numerical weather forecasts. The emergence of artificial intelligence algorithms has provided new perspectives in this field, but the extension of algorithms developed for station networks with rich historical records to include newly-built stations remains a challenge. To address this, we design a framework that combines two machine learning methods: temperature prediction based on ensemble of multiple machine learning models and transfer learning for newly-built stations. We then evaluate this framework by post-processing temperature forecasts provided by a leading weather forecast center and observations from 301 weather stations in China. Station clustering reduces forecast errors by 24.4% averagely, while transfer learning improves predictions by 13.4% for recently-built sites with only one year of data available. This work demonstrates how ensemble learning and transfer learning can be used to supplement weather forecasting.
Comparison of pore fabric based on high-resolution X-ray computed tomography and magnetic pore fabric in sedimentary rocks
Authors: Zhou Yi , Pugnetti Michele , Foubert Anneleen , Neururer Christoph , R. Biedermann Andrea
Published: March 2020

Pore fabrics characterize pore geometry and network in rocks. The pore size, connectivity and elongation direction determine the permeation ability and preferred permeation direction. X-ray micro-tomography (XRCT) is a widely used technique to visualize the inner structure of rock samples. Based on XRCT data, digital rock models can be generated and analyzed to visualize and quantify pore shape distribution, pore sizes and the connectivity of pores. To measure the magnetic pore fabric (MPF), samples are impregnated with ferrofluid prior to measuring anisotropy of magnetic susceptibility. This technique could be complementary to existing techniques to capture smaller pores. Empirical relationships exist between pore fabric or permeability anisotropy and MPF, and the aim of this study is to quantitatively test these relationships. In this study, Upper Marine Molasse sandstone (OMM, Belpberg, Switzerland) with 10-20% porosity and relatively homogeneous pore structure, and Plio-Pleistocene calcarenite (Apulia, Italy) with ~50% porosity and complex pore structure, are tested. To understand the pore networks of these rock types, an integrated approach has been applied including standard pycnometer porosity measurements, MPFs, XRCT, and porosity and permeability simulations based on XRCT analyses. The average equivalent diameter of pores based on micro-CT is ~150 μm for the Molasse sandstone, and ~300 μm for calcarenite. XRCT data indicate preferential alignment of the long axes of the pores, and both MPFs and simulated permeabilities are anisotropic in these samples. For calcarenite with large pores, the direction of the maximum magnetic susceptibility coincides with the direction of the maximum grouping of long pore axes. Simulated permeability is affected by other factors in addition to the grouping of long pore axes, including porosity, pore size, connectivity and tortuosity of pores. Therefore, the next step of this study will compare laboratory-measured directional permeabilities with permeability simulations and with MPFs, to investigate their potential for predicting the preferred fluid flow direction in these samples. For the full understanding of MPFs, more types of sedimentary rocks will be analyzed. If MPFs prove a good and quantitative proxy for pore fabric characterization in hydrocarbon and geothermal studies, more measurements can be made in the future, making it possible to investigate regional-scale variations.
Offshore stratigraphic and geomorphological record of northeastern Ireland
Authors: Coughlan Mark , Wheeler Andy , Long Mike , O'Toole Ronan , Service Matthew
Published: March 2020

The onshore exposures on the northeast coast of the island of Ireland have been well studied in relation to regional glacial advances of the British and Irish Ice Sheet (BIIS) and changes in relative sea level change. These includes sites around Dundalk Bay, Carlingford Lough and Kilkeel in particular. During deglaciation of the BIIS, two important readvance phases are recorded locally; the Clogher Head and Killard Point Stadials. However, the offshore extent and record of these events is still poorly constrained. Understanding the nature and pattern of deglaciation of the offshore sectors of the BIIS is important to any attempt to reconstruct its history after the Last Glacial Maximum.

This study presents a new seismo-stratigraphic analysis of submarine Quaternary deposits nearshore, off the northeast coast of the island of Ireland. This includes multibeam echosounder (MBES), sparker seismic and core data from the areas of offshore Dundalk Bay, Carlingford Lough, Kilkeel and Dundrum Bay. Preliminary analysis of the data reveals a series of geomorphic features in each area including moraines, eskers, drumlinised landscapes, exposed till surfaces and infilled channels. Sediment cores will be used to further groundtruth these features and provide insights into their formation processes and timing. Initial inspection of these cores suggest two diamicton facies, assumed to be subglacial till, in the area of Kilkeel. This presentation will include results to date from this study with the aim of elucidating the glaciation and deglaciation history of geomorphologically complex area.
Constructing an earthquake simulator
Authors: Eleftheriou Maria
Published: March 2020

Earthquakes are natural or man-made events that can occur everywhere in the Earth. Many regions in our planet have the disadvantage to experience more earthquakes compared to other regions, for example in the areas near the boundaries of the tectonic plates. Therefore it is very important to have a course in the schools where pupils learn about earthquakes but also learn what have to be avoided in the construction of the buildings. For this reason pupils construct an earthquake simulator (platform) using simple materials in the course of geography-geology. The simple materials are cardboards, tape, balloons, or small balls and other cheap materials. Pupils construct small structures with one or two floors from different materials in order to observe how these different structures will behave in a possible earthquake. Pupils vibrate the platform randomly or with more concrete way for example they vibrate the platform in a longitudinal or in a transversal way. Additionally pupils fasten a mobile phone in the platform and observe the acceleration of the platform through a suitable application.
Volcanic influence on STRATOCLIM aircraft observations 2017 in the Asian Monsoon, studies with the transient CCM EMAC
Authors: Brühl Christoph , Schlager Hans , Weigel Ralf , Appel Oliver , Borrmann Stephan , Lelieveld Jos , Schallock Jennifer
Published: March 2020

Results from a transient 28 year simulation with the chemistry climate model EMAC with interactive modal aerosol scheme nudged to observed tropospheric meteorology (ERA-Interim) which includes about 500 volcanic SO2 injections are compared with in situ aircraft observations in the UT/LS in the Asian Monsoon anticyclone. Enhanced SO2 observed by STRATOMAS and enhanced sulfate aerosol observed by ERICA in the LS point to impact of several explosive eruptions of the Indonesian volcano Sinabung during summer 2017 seen by the OSIRIS satellite instrument. This is supported by freshly nucleated particles observed by COPAS in the UTLS. We present several sensitivity studies with EMAC with different assumptions on the injection patterns in comparison to the observations in July/August 2017.  
The monsoon dynamics distributes the volcanic material together with Asian pollution into the global lower stratosphere.
Substantial twentieth-century Arctic warming caused by ozone-depleting substances
Authors: Polvani Lorenzo , Previdi Michael , England Mark , Chiodo Gabriel , Smith Karen
Published: March 2020

The rapid warming of the Arctic, perhaps the most striking evidence of climate change, is believed to arise from increases in atmospheric concentration of greenhouse gases since the industrial revolution.  While the dominant role of carbon dioxide is undisputed, another important set of anthropogenic greenhouse gases was also being emitted over the second half of the twentieth century: ozone-depleting substances (ODS).  These compounds, in addition to causing the ozone hole over Antarctica, have long been recognized as powerful greenhouse gases.  However, their contribution to Arctic warming has not been quantified to date.  We do so here by analyzing ensembles of climate model integrations specifically designed for this purpose, spanning the period 1955-2005 when atmospheric concentrations of ODS increased rapidly.  We show that when ODS are kept fixed the forced Arctic surface warming, and the forced sea ice loss, are only half as large as when ODS are allowed to increase.  We also demonstrate that the large Arctic impact of ODS occurs primarily via direct radiative warming, not via ozone depletion.  Our findings reveal a substantial, and hitherto unrecognized, contribution of ODS to recent Arctic warming and highlight the importance of the Montreal Protocol as a major climate change mitigation treaty.
Precise LEO satellite orbit determination and Earth gravity field modeling with carrier-range method
Authors: Gao Geng , Zou Xiancai , Zhang Shoujian , Liu Bingshi
Published: March 2020

Precise LEO satellite orbit determination(OD) and Earth gravity field modeling are researched in this study.

Firstly, on the basis of Precise Point Positioning Ambiguity Resolution(PPPAR), a kinematic LEO satellite OD algorithm based on the epoch-difference and post-facto iteration is introduced, which plays a vital rule in the detection of the phase cycle slip to achieve the best orbit accuracy. The experiments of GRACE satellite OD with zero-difference IF combination observations spanning one year of 2010 show that, compared to the JPL reference orbits, the daily average 3D RMS is generally below 5.0cm for the float solution, while that is below 4.0cm for the fixed solution.

Secondly, to solve the problem that specific a-priori information like earth gravity field model must be involved in LEO’ reduced dynamic OD, the simultaneous solution method, which is specially on the relation with the kinematic OD and reduced dynamic OD, is used and the carrier-range, which can be recovered from phase observations once the kinematic OD process using Integer Ambiguity Resolution (IAR) technology is carried out, is naturally applied to this method. With the experiments based on the data over a period of the year of 2010, comes some evacuations, including the external checks on the accuracy of the orbits and the analysis on the earth gravity model. The numerical results show that, compared to the JPL reference orbits, the 3D RMS is below 3.0cm and the RMS is below 2.0cm for each component. As for the accuracy of gravity field model, compared to some contemporary significant earth gravity model, the model of the single month solution behaves very well below the 60 degree of the gravity field’s coefficients, while over the 60 degree, only the UTCSR model quite corresponds to the model computed by this method. Therefore, due to the promotion of the orbital accuracy and gravity field model, we suggest that the recovered carrier-range should be implemented in the simultaneous method for the better product solution of the LEO’s missions.
A NLS-4Dvar Assimilation System of Surface PM2.5 with WRF-CMAQ Model : Observing System Simulation Experiments
Authors: Zhang Shan , Tian Xiangjun , Zhang Hongqin , Han Xiao , Zhang Meigen
Published: March 2020

        While complete atmospheric chemical transport models have been developed to understanding the complex interactions of atmospheric chemistry and physics, there are large uncertainties in numerical approaches. Data assimilation is an efficient method to improve model forecast of aerosols with optimized initial conditions. We have developed a new framework for assimilating surface fine particulate matter (PM2.5) observations in coupled Weather Research and Forecasting (WRF) model and Community Multiscale Air Quality (CMAQ) model, based on nonlinear least squares four-dimensional variational (NLS-4DVar) data assimilation method. The NLS-4DVar approach, which does not require the tangent and adjoint models, has been extensive used in meteorological and environmental areas due to the low computational complexity. Two parallel experiments were designed in the observing system simulation experiments (OSSEs) to evaluate the effectiveness of this system. Hourly PM2.5 observations over China be assimilated in WRF-CMAQ model with 6-h assimilation window, while the background state without data assimilation is conducted as control experiment. The results show that the assimilation significantly reduced the uncertainties of initial conditions (ICs) for WRF-CMAQ model and leads to better forecast. The newly developed PM2.5 data assimilation system can improve PM2.5 prediction effectively and easily. In the future, we expect emission to be optimized together with concentrations, and integrate meteorological assimilation into aerosol assimilation system.
magnetic reconnection onset from electron phase to ion phase
Authors: Wang Rongsheng
Published: March 2020

It is still unresolved that how magnetic reconnection is triggered in the collisionless environment. In this talk, we will present that the reconnection onset consists of two phases: the electron phase and ion phase. In the electron phase, the electrons are significantly energized and super-alfvenic electron jets are created while the ion bulk flows haven't been formed and the ions haven't been heated. Later on, the ion jets are produced together with the electron jets in the ion phase. The main reason for such two phases is discussed. A particle-in-cell simulation was performed to realize these two phases during reconnection onset. 

 
Timely information on birch and grass pollen levels in Belgium
Authors: Verstraeten Willem W. , Bruffaerts Nicolas , Kouznetsov Rostislav , Hendrickx Marijke , Sofiev Mikhail , Delcloo Andy W.
Published: March 2020

Air pollution has tremendous effects on mortality and the quality of life. Air pollution is not restricted to anthropogenic contaminants only, since also natural sources (soils, lakes, marshes, vegetation, volcanoes, etc) may emit substantial amounts of unhealthy pollutants (VOCs, SOX, NOX, aerosols, etc). Releases of biogenic aerosols such as pollen affect the public health badly, putting additional distress on people already suffering from cardiovascular and respiratory diseases. In Belgium, ~10% of the people is estimated to suffer from allergies due to pollen released by the birch family trees and ~15% due to pollen emitted by grasses. In some European countries the prevalence is up to 40%.

To date, the only available airborne pollen level data in Belgium are retrieved by Sciensano at five stations that monitor off-line daily concentrations of grass and birch pollen among other species. Patients suffering from rhinitis have therefore no access to detailed real-time spatial information and warnings on forthcoming exposures.

Chemistry Transport Models (CTM) can both quantify as well as forecast the spatial and temporal distribution of airborne birch and grass pollen concentrations if accurate and updated maps of birch and grass pollen emission sources are available, and if the large inter-seasonal variability in emissions is considered.

Here we show the results of the modelled spatio-temporal distributions of grass and birch pollen over Brussels and other locations in Belgium using the CTM SILAM. This CTM is driven by ERA5 meteorological reanalysis data from ECMWF, an updated MACC-III birch tree fraction map, based on local information, and a grass pollen emission map showing the spatial distribution of the potential pollen sources. Pollen release is based on the temperature degree days approach. Inter-seasonal variability in birch pollen release was taken into account by using spaceborne MODIS vegetation activity (Gross Primary Productivity, GPP). For grass pollen this approach does not fit, therefore we use average temperature and precipitation of the previous year in a first approach.

SILAM modelled and observed time series of daily birch pollen levels of 50 birch pollen seasons at multiple sites in Belgium correlate well for the period 2008-2018 with an increased R² of up to ~50% compared to the reference run. What is more, SILAM is able to capture the allergy thresholds of 50 and 80 pollen grains m-³ exposure from the observations for birch trees. Grass pollen simulations are in progress.
Normal faulting above salt wedges in tilted continental margins: numerical modeling
Authors: Hamdani Itzhak , Aharonov Einat , Olive Jean-Arthur , Pařez Stanislav , Gvirtzman Zohar
Published: March 2020

Most salt basins are highly deformed and consist of complex faulting systems that is difficult to reconstruct. In contrast, in the Levant basin, the deformation of the Pliocene-Quaternary overburden on top of the Messinian salt is relatively mild, providing a rare opportunity to explore a young salt basin in its early stages of evolution. In the Levant continental margin normal faulting occurs mainly above the wedge of the salt layer where it rapidly thins from a few hundred meters to less than 100m. Recently, chronology of faulting in the Levant continental margin improved. It was indicated that during the Pliocene (duration of 2.7 My) faulting activity was minor. In the Gelasian (duration of 0.8 My) faulting activity peaked alongside huge slumping. Then, in the past 1.8 My, faulting and slumping had both decreased, although they are still mildly active today.

These observations raise questions such as: why didn't faulting start immediately after salt deposition? Why had faulting peaked when it did, and then why did it decrease? In this work we wish to understand the mechanism of normal faulting in continental slopes bordering salt basins. What drives salt motion? How does this motion cause faulting in overriding rocks? Where exactly will faults initiate and how will they progress in space? What controls the rate of faulting and when will they shut down?

This study uses 2D numerical simulations to explore these questions. The model assumes that salt is viscous and its overriding rock is brittle and viscoelastic. The model uses a Stokes flow solver, specifically a finite difference/particle-in-cell numerical approach, that can simulate both viscous and elasto-plastic–brittle rheology.

Answering these questions will contribute to the understanding of halokinematics in young salt basins and will allow better assessment of seismic hazards related to salt related deformation.