bluuebunny/crossref_metadata_2025 huggingface dataset:
Mineral mapping at the Ikh Shankhai porphyry Cu deposits, Mongolia using WorldView-3 data
Authors: Youngsun Son , Kwang-Eun Kim
Published: March 2020

Southeastern Mongolia has limited access due to its extreme environments (long and harsh winter) and lack of infrastructure (e.g., road). Satellite remote sensing technique is one of the most effective methods to get geological information in areas where field survey is difficult. WorldView-3 (WV3), launched in August 2014, is high-spatial resolution commercial multispectral sensor developed by DigitalGlobe. WV3 measures reflected radiation in eight visible near infrared (VNIR) bands between 0.42 and 1.04 ㎛ and in eight short-wave infrared (SWIR) bands between 1.20 and 2.33, which have 1.24- and 7.5-m spatial resolution, respectively. In this study, WV3 VNIR and SWIR data were used to identify and map the various minerals in the Ikh Shankhai porphyry Cu deposit district, Mongolia.

The Ikh-Shankhai porphyry Cu deposit is located within Gurvansayhan island arc terrane in southeastern (SE) Gobi mineral belt, Mongolia. The Ikh-Shankhai district include the porphyry system containing Cu-Au with primary chalcopyrite, which is classified into disseminated type and stockwork quartz type. This district consists of Late Devonian-Early Carboniferous andesite, tuff and siltstone intruded by Carboniferous-Permian granite, granodiorite and granodiorite porphyry.

The WV 3 data were analyzed using mixture-tuned-matched filter (MTMF) which locates a known spectral signature in the presence of a mixed or unknown background. MTMF does not require knowledge of all of the spectral endmembers and is suited for used where materials with distinct spectral signatures occur within a single pixel. From the WV3 analysis result using mixture-tuned-matched filter (MTMF), we identified the location and abundance of alteration minerals. Advanced argillic minerals (alunite, kaolinite (or dickite), and pyrophyllite) were dominant in the lithocaps of the Budgat and Gashuun Khudag prospects; whereas, phyllic (illite) and propylitic (calcite and epidote) minerals were dominant in the areas surrounding the lithocaps. In addition, the distribution of ferric minerals (hematite and goethite) was mapped because of the oxidation of pyrite. Field work at the Ikh-Shankhai porphyry Cu district to evaluate the accuracy of the mineral mapping results was carried out in August, 2018. Reflectance spectra acquisition using a portable ASD TerraSpec Halo mineral identifier (the attached GPS covered a spectral range of 0.35 – 2.5 µm) was conducted in the altered outcrops of the Ikh-Shankhai porphyry Cu district. Mineral mapping results compared well with the field spectral measurements collected for the ground truth and demonstrated WV3 capability for identifying and mapping minerals associated with hydrothermal alteration. Evaluation of the WV3 mineral mapping results using ground truth data indicates, however, a difficulty in mapping spectrally similar minerals (e.g., kaolinite and dickite) due to spectral resolution limitation.
Photo-Induced Heterogeneous Chemistry of Reactive Species on Aerosol Surfaces: Using Photo-Fragmentation Laser Induced Fluorescence for the Measurement of Nitrous Acid Production from Titanium Dioxide Aerosols
Authors: Dyson Joanna , Boustead Graham , Fleming Lauren , Blitz Mark , Stone Daniel , Arnold Stephen , Whalley Lisa , Heard Dwayne
Published: March 2020

The hydroxyl radical (OH) is the main oxidant in the troposphere and is vitally important for its role in the removal of greenhouse gases such as methane from the atmosphere. Moreover, the OH radical also has a role in the formation of secondary pollutants such as tropospheric ozone and secondary organic aerosols (SOAs), formed via the oxidation of volatile organic compounds (VOCs). Understanding the sources and sinks of OH within the atmosphere is therefore crucial in order to fully understand the concentration and distribution of trace atmospheric species associated with climate change and poor air quality.

In polluted environments the dominant source of OH to initiate oxidation is the photolysis of nitrous acid (HONO). Current atmospheric chemistry models underestimate the concentration of HONO indicating a potential missing tropospheric source of HONO. There is a large uncertainty in the production of HONO from the contribution and role of aerosols and heterogeneous chemistry both under light and dark conditions.

In order to investigate the missing source of HONO from illuminated aerosols and determine its atmospheric relevance, a photo-fragmentation laser induced fluorescence (PF-LIF) instrument coupled to an aerosol flow tube system has been constructed. The PF-LIF instrument provides a highly sensitive measurement of HONO by fragmenting it into OH which is then detected in a low pressure cell by LIF. The aim of this system is to measure the rate of production of HONO from illuminated aerosol surfaces.

We will present an overview of the PF-LIF instrument and results from experiments investigating the reactive uptake of NO2 by TiO2 aerosols to produce HONO. The change in the reactive uptake coefficient as a function of NO2 concentration and the dependence of HONO production on relative humidity and light intensity will also be discussed.   
First evidence of plastic fallout from the Great Pacific Garbage Patch
Authors: Egger Matthias , Sulu-Gambari Fatimah , Lebreton Laurent
Published: March 2020

Increasing amounts of plastic debris in the ocean is a global environmental concern. Each year, several million tons of plastic waste enter the ocean from coastal environments. Transported by currents, wind and waves, positively buoyant plastic objects eventually accumulate at the sea surface of subtropical oceanic gyres, forming the so-called ocean garbage patches. To date, the fate of floating plastic debris ‘trapped’ in the oceanic gyres remains largely unknown. To more accurately assess the persistence of floating plastics accumulating in offshore areas, a better understanding of the plastic inputs and outputs into and from ocean garbage patches is crucial. An important component of this mass balance currently missing is the vertical plastic flux from the sea surface of subtropical waters towards the seabed. Numerical models have major difficulties in constraining the sinking flux of plastic to the ocean interior in these areas since validation against observational data is not possible yet.

Here, we provide the first water column profiles (0-2000m water depth) of plastic particles (>500µm) in the North Pacific subtropical gyre (Great Pacific Garbage Patch; GPGP). We show that plastic particles in the water column are mostly in the size range of particles that are apparently missing from the ocean surface and that their polymer composition is similar to that of floating debris circulating in the surface waters. Furthermore, water column plastic concentrations increase with higher concentrations at the sea surface and show a power law decline with water depth. These findings strongly suggest that plastics present in the deep sea below the GPGP are small fragments of initially buoyant plastic debris that accumulated at the sea surface. Although the amount of plastic in the GPGP water column is significant compared to the surface accumulation, our results further indicate that the ocean water column is unlikely to harbor a major fraction of the tens of millions of metric tons of missing ocean plastic.
Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere
Authors: Palmroth Minna , Grandin Maxime , Helin Matti , Koski Pirjo , Oksanen Arto , Glad Minna , Valonen Rami , Saari Kari , Bruus Emma , Norberg Johannes , Viljanen Ari , Kauristie Kirsti , Verronen Pekka
Published: March 2020

Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently scientists reported of citizens' observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. Here, we present a new auroral form named "the dunes". On Oct 7, 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyse the photographs, and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. We conclude that the the dunes may provide new insights into the structure of the mesopause as a response to driving by ionospheric energy deposition via Joule heating and electron precipitation. Further, our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. The dune project presents means to create general interest towards physics, emphasising that citizens can take part in scientific work by helping to uncover new phenomena.
Effects of large scale advection and small scale turbulence on vertical phytoplankton dynamics
Authors: Beltram Tergolina Vinicius , Berti Stefano , Mompean Gilmar
Published: March 2020

When studying the life cycle of phytoplankton frequently one is interested in the survival or death conditions of a population (bloom/no bloom). These dynamics have been studied extensively in the literature through a range of modelling scenarios but in summary the main factors affecting the vertical dynamics are: Water column mixing intensity, solar energy distribution, nutrients availability and predatory activity. The later two can be represented by different biological models whereas the vertical mixing is usually parameterized by a diffusive process. Even though turbulence has been recognized as a paramount factor in the survival dynamics of sinking phytoplankton species, dealing with the multi scale nature of turbulence is a formidable challenge from the modelling point of view. In addition, convective motions are being recognized to play a role in the survival of phytoplankton throughout winter stocking. With this in mind, in this work we revisit a theoretically appealing  model for phytoplankton vertical dynamics with turbulent diffusivity and numerically study how large-scale fluid motions affect its survival and extinction conditions. To achieve this and to work with realistic parameter values, we adopt a kinematic flow field to account for the different spatial and temporal scales of turbulent motions. The dynamics of the population density are described by a reaction-advection-diffusion model with a growth term proportional to sun light availability. Light depletion is modelled accounting for water turbidity and plankton self-shading; advection is represented by a sinking speed and a two-dimensional, multiscale, chaotic flow. Preliminary results show that under appropriate conditions for the flow, our model reproduces past results based on turbulent diffusivity. Furthermore, the presence of large scale vortices (such as those one might expect during winter convection) seems to hinder survival, an effect that is partially mitigated by turbulent  diffusion.
Impact of the Ambae, Raikoke and Ulawun eruptions in 2018-2019 on the global stratospheric aerosol layer and climate
Authors: Kloss Corinna , Sellitto Pasquale , Legras Bernard , Vernier Jean-Paul , Jégou Fabrice , Ratnam M. Venkat , Kumar B. Suneel , Madhavan B. Lakshmi , Eremenko Maxim , Berthet Gwenaël
Published: March 2020

Using a combination of satellite, ground-based and in-situ observations, and radiative transfer modelling, we quantify the impact of the most recent moderate volcanic eruptions (Ambae, Vanuatu in July 2018; Raikoke, Russia and Ulawun, New Guinea in June 2019) on the global stratospheric aerosol layer and climate.

For the Ambae volcano (15°S and 167°E), we use the Stratospheric Aerosol and Gas Experiment III (SAGE III), the Ozone Mapping Profiler Suite (OMPS), the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Himawari geostationary satellite observations of the aerosol plume evolution following the Ambae eruption of July 2018. It is shown that the aerosol plume of the main eruption at Ambae in July 2018 was distributed throughout the global stratosphere within the global large-scale circulation (Brewer-Dobson circulation, BDC), to both hemispheres. Ground-based LiDAR observations in Gadanki, India, as well as in-situ Printed Optical Particle Spectrometer (POPS) measurements acquired during the BATAL campaign confirm a widespread perturbation of the stratospheric aerosol layer due to this eruption. Using the UVSPEC radiative transfer model, we also estimate the radiative forcing of this global stratospheric aerosol perturbation. The climate impact is shown to be comparable to that of the well-known and studied recent moderate stratospheric eruptions from Kasatochi (USA, 2008), Sarychev (Russia, 2009) and Nabro (Eritrea, 2011). Top of the atmosphere radiative forcing values between -0.45 and -0.60 W/m2, for the Ambae eruption of July 2018, are found.

In a similar manner the dispersion of the aerosol plume of the Raikoke (48°N and 153°E) and Ulawun (5°S and 151°E) eruptions of June 2019 is analyzed. As both of those eruptions had a stratospheric impact and happened almost simultaneously, it is challenging to completely distinguish both events. Even though the eruptions occurred very recently, first results show that the aerosol plume of the Raikoke eruption resulted in an increase in aerosol extinction values, double as high as compared to that of the Ambae eruption. However, as the eruption occurred on higher latitudes, the main bulk of Raikoke aerosols was transported towards the northern higher latitude’s in the stratosphere within the BDC, as revealed by OMPS, SAGE III and a new detection algorithm for SO2 and sulfate aerosol using IASI (Infrared Atmospheric Sounder Interferometer). Even though the Raikoke eruption had a larger impact on the stratospheric aerosol layer, both events (the eruptions at Raikoke and Ambae) have to be considered in stratospheric aerosol budget and climate studies.
The influence of radiative forcing on permafrost temperatures in Arctic rock walls
Authors: Schmidt Juditha , Westermann Sebastian , Etzelmüller Bernd , Magnin Florence
Published: March 2020

Climate change has a strong impact on periglacial regions and intensifies the degradation of mountain permafrost. This can result in instabilities of steep rock walls as rock- and ice-mechanical properties are modified. Besides altitude and the related air temperature, latitude is a crucial factor, as solar radiation has a strong impact on the energy transfer processes from the atmosphere to the ground. It can differ significantly in intensity and time over latitudinal positions and exposures of frozen rock slopes.

In this project, we suggest improving the parametrization of short-wave and long-wave radiation in thermal models for permafrost degradation. To achieve this, we will analyze temperature data of surface temperature loggers from Southern Norway to Svalbard. In total, 37 loggers were installed between 2010 and 2017. The field sites display enormous latitudinal gradients as well as topographic settings. Furthermore, they provide hourly data, allowing us to set up short-stepped time series for examination of solar radiation angles at varying latitudes.

The data is used to set up a transient heat-flow model (CryoGrid) to simulate the local thermal regime. The model takes into account varying input of short-wave radiation due to aspect, slope angle and time as well as long-wave radiation under different sky-view factors. Finally, the influence of solar radiation on permafrost degradation in steep rock walls is investigated.
Township Spatial Commodification and Environmental Spatial Disaster under the Threat of Climate Change: Flooding and Development of (Taiwan) Zhubei Urbanization
Authors: Hung Chi-Tung , Lin Wen-Yen , Lin Shih-Han
Published: March 2020

Agriculture land has been treated as the urban reserved land which has potential value for transformation. Especially for the land development strategy by “Developmental Government”, agriculture land’s value is twisted and encouraging trading activity, that result in lower production and short in food supply. The threats from extreme weather and environmental change has increased the potential hazards of landuse and challenges toward town planning. This study uses environmental diagnosis and field survey with in-depth interviews, along with the result from FLO-2D flood model and GIS overlay of hazard risk maps, to proceed with a case of “property-led development” in (Taiwan, Xinzhu) Zhubei city. The findings indicate that run-off volume of some area has changed and the flooding depth / area has increased. By interpreting the empirical results, it has exposed the environmental hazard issues and land commodification by the failure of urban planning policy in Zhubei city.
Cockade-bearing breccias, cataclasites and gouges in a single fault zone: Microstructures and geochemisty
Authors: Berger Alfons , Herwegh Marco
Published: March 2020

The seismic-interseismic cycle strongly relates to the interplay between dilation owing to fracturing and frictional granular flow on one hand side and hydrothermal cementation processes on the other side. This study investigates different fault rocks of a crustal-scale fault zone in the Central Alps (Switzerland). We combine microstructural with geochemical approaches to decipher the interaction of grain size reduction via frictional processes with precipitation and resulting particle size increases. The three major fault rocks, i.e. (1) cockade-bearing breccias, (2) cataclasites, and (3) fault gouges, differ in their microstructure. The chemical data clearly demonstrate a decreasing gain of volume along this group of tectonites. Their different precipitation volumes most likely relate to dynamic changed of the local permeability of these rocks. The fluid pathways control the precipitation at different localities and times, which affect the healing of these fault rocks inducing a gain in rock strength. During the next deformation event, the extent of healing therefore directly controls the mechanical behavior of the rock. The estimated volume gain (~+110%) in cockade-bearing breccias is consistent with the seismic dilatant behavior of these frictional rocks as already proposed from other arguments (Berger and Herwegh 2019). This is in contrast to the fault-gouges with only minor gains in volume and mass resulting in a predominantly non-cohesive deformation style. This example indicates that permeability evolution (and related hydrothermal processes) strongly influences the mechanical behavior of such faults. This shows the highly dynamic behavior with time in long-lived fault systems. These dynamic changes in precipitation and resulting different strengths occur at different timescales from minutes (seismic events) to thousands of years.

Ref.: Berger, A., Herwegh, M., 2019. Cockade structures as a paleo-earthquake proxy in upper crustal hydrothermal systems. Nature Scientific Reports, 9, 9209.
GIS and remote sensing-based framework for urban greenspaces management: assessment of vulnerability to typhoons in Taiwan
Authors: Nguyen Kim-Anh , Liou Yuei-An
Published: March 2020

Typhoon is one of the most severe natural hazards. It can cause great damages to the people, properties, and greenspace infrastructure. Greenspaces include parks, gardens, play grounds, plants, etc. In urban areas, greenspaces are highly prone to be affected by typhoons resulting dangers to humans, infrastructure, and transportation. This study introduces a vulnerable assessment framework of urban greenspaces (UGSs) to typhoons by using remote sensing data and GIS techniques. The key purpose is to mitigate potential damages of urban greenspace and other related risks associated with typhoons. Firstly, we analyze the typhoon characteristics; identify the impacts of typhoons on the UGSs in Taiwan; and derive the UGSs information (biological and physical features) from multi-sensor satellite images to build GIS database for the UGS server for further assessment. Secondly, we derive the soil characteristics from the soil map and remote sensing data; propose an vulnerable assessment framework to evaluate the vulnerability of the UGSs to typhoon in major cities in Taiwan. Thirdly, we improve and test the R3GIS platform after integrating with new tools of assessing vulnerability of UGSs to typhoons for demonstration of its benefits to UGS management in Taiwan. The outcomes will be expected to support warning system to serve the related authorities for mitigating the damages of typhoons on UGSs and communities. The vulnerability of UGS in Taiwan to typhoon winds can be assessed via three domains: (i) typhoon characteristics; (ii) UGSs features; and (iii) soil composition. These components will be captured via multi-sub indicators that reveal the possibility whether trees in the UGS will fail during the threat of typhoons and related risks. Thus, the combination of all mentioned domains/indicators in the vulnerability assessment framework thas a potential to provide a warning to related authorities with possible solutions for lesseing the damages of both UGS and public properties. In EGU meeting we are going to introduce an overall concept of the research work and the first phase results of the study such as typhoon characteristics and features of urban greenspaces in Taiwan, and the conceptual UGS vulnerability assessment framework.
Distributed fibre-optic temperature sensing in a 1 km borehole drilled on a fast-flowing glacier in Greenland
Authors: Law Robert , Christoffersen Poul , Hubbard Bryn , Doyle Samuel , Chudley Thomas , Bougamont Marion , Schoonman Charlie
Published: March 2020

Whilst marine-terminating glaciers in Greenland are significant contributors to global sea level rise, their thermodynamics are poorly constrained by observations. Conventional discrete thermistor borehole sensing studies go some way to addressing this but lack the spatial resolution to effectively resolve key processes. Here, we detail results from fibre optic distributed temperature sensing equipment installed in a 1040 m hot water drilled borehole 28 km inland of the calving front of Store Glacier, Greenland. Surface ice velocity at the borehole is 550 m a-1 with convergent ice flow into a bedrock trough. Spatial resolution of 0.25 m, temperature differences of 0.03 °C, and an absolute temperature accuracy of 0.15 °C were achieved. 0.5 °C warm anomalies were observed between 0-30 and 220-45 m depth with a central cold section down to -22 °C . We interpret the former anomaly to be a result of cryo-hydrologic warming, although of lower magnitude than in slow-flowing sectors of the Greenland Ice Sheet. The latter is theorised to be strain heating, supported by deformation observed in the cable at this point. The record also reveals a 75 m thick section of temperate basal ice and the nature of the cold-temperate transition as a sharp temperature drop of 0.45 °C over 1.5 m at the top of the temperate layer, with notable temperature changes in the vicinity of the transition. Warming of 0.06 °C is observed over the basal 6 m of the profile. The cable lasted 6 weeks before failure, demonstrating the feasibility of using  fibre optic sensing to study thermal processes in a glacier environment with high deformation rates.
An update on brightening and dimming in the United States
Authors: Augustine John
Published: March 2020

Brightening and dimming of solar irradiance at Earth’s surface is a multidecadal phenomenon that occurs globally. Generally, over the past century, there have been two brightening periods (1920s to 1950s, 1980s to the early 2000s) and one dimming period (1950s to mid-1980s). Exceptions are the evolving industrial regions of India and parts of China that have only experienced dimming owing to aerosol effects. The two most recent dimming and brightening periods in Europe were attributed to both aerosol and cloud variability. In the U.S., especially since the 1990s, the systematic variation of cloud cover has been the dominant influence on brightening and dimming.

From 1996 through 2011 downwelling surface solar irradiance over the U.S. increased by +6.6 Wm-2/decade in an environment of decreasing cloud cover and decreasing aerosol optical depth (AOD) [Augustine and Dutton 2013]. Results presented here extend the brightening/dimming trend for the U.S. through 2018 and show that brightening continued for only one more year after 2011. Following 2012, solar irradiance at the surface abruptly retreated to the long-term mean (±1 Wm-2) and stabilized at that level through 2017. In 2018 there was a slight decrease of solar irradiance at the surface resulting in a slight dimming trend of -1.7 Wm-2/decade from 2013 through 2018. During that period AOD continued to decrease but mean cloud cover increased by about 1%, thus cloud variability continued to be the dominant influence on brightening/dimming in the U.S.

It has been shown that the direct effect of aerosols cannot account for the magnitudes of observed trends of surface solar irradiance over the U.S. [Augustine and Dutton 2013]. Here, we show that the second indirect effect of aerosols is consistent with the magnitudes of cloud and AOD reduction from 1996 through 2011. However, over the latest 6-year period analyzed, trends in cloud cover and AOD are not consistent with the stabilization (or small reduction) of solar irradiance at the surface with respect to both the direct and second indirect effect of aerosols. Therefore, systematic changes in circulation and weather must be considered to explain the observed variability, especially with regard to clouds. In this presentation we present evidence for a mechanism that could possibly have been a major contributor to brightening and dimming in the U.S. and western Europe over the past century.

 

Augustine, J. A., and E. G. Dutton (2013), Variability of the surface radiation budget over the United States from 1996 through 2011 from high-quality measurements, J. Geophys. Res.,118, doi:10.1029/2012JD018551.
Influence of Urbanization on Precipitation and Flooding Caused by Landfalling Tropical Cyclones: The Case of Houston
Authors: Villarini Gabriele , Zhang Wei , Vecchi Gabriel , Smith James
Published: March 2020

We examine the impact of urbanization on precipitation and flooding caused by tropical cyclones under a dynamical modeling framework, using Hurricane Harvey (2017) and Tropical Storms Allison (2001) and Imelda (2019) as case studies. Hurricane Harvey poured more than a metre of rainfall across the heavily populated Houston area, leading to unprecedented flooding and damage. Although studies have focused on the contribution of anthropogenic climate change to this extreme rainfall event, limited attention has been paid to the potential effects of urbanization on the hydrometeorology associated with this hurricane. Here we find that urbanization exacerbated not only the flood response but also the storm total rainfall. Using the Weather Research and Forecast model—a numerical model for simulating weather and climate at regional scales—and statistical models, we quantify the contribution of urbanization to rainfall and flooding. We expand these analyses to examine the impacts of urbanization on Tropical Storms Allison and Imelda, two other storms that affected the Houston area causing widespread heavy rainfall and flooding.
Big Data Assimilation: Real-time Workflow for 30-second-update Forecasting and Perspectives toward DA-AI Integration
Authors: Miyoshi Takemasa , Honda Takmi , Otsuka Shigenori , Amemiya Arata , Maejima Yasumitsu , Ishikawa Yoshihiro , Seko Hiromu , Yoshizaki Yoshito , Ueda Naonori , Tomita Hirofumi , Ishikawa Yutaka , Satoh Shinsuke , Ushio Tomoo , Koike Kana , Nakada Yasuhiko
Published: March 2020

The Japan’s Big Data Assimilation (BDA) project started in October 2013 and ended its 5.5-year period in March 2019. The direct follow-on project was accepted and started in April 2019 under the Japan Science and Technology Agency (JST) AIP (Advanced Intelligence Project) Acceleration Research, with emphases on the connection with AI technologies, in particular, an integration of DA and AI with high-performance computation (HPC). The BDA project aimed to fully take advantage of “big data” from advanced sensors such as the phased array weather radar (PAWR) and Himawari-8 geostationary satellite, which provide two orders of magnitude more data than the previous sensors. We have achieved successful case studies with newly-developed 30-second-update, 100-m-mesh numerical weather prediction (NWP) system based on the RIKEN’s SCALE model and local ensemble transform Kalman filter (LETKF) to assimilate PAWR in Osaka and Kobe. We have been actively developing the workflow for real-time weather forecasting in Tokyo in summer 2020. In addition, we developed two precipitation nowcasting systems with the every-30-second PAWR data: one with an optical-flow-based system, the other with a deep-learning-based system. We chose the convolutional Long Short Term Memory (Conv-LSTM) as a deep learning algorithm, and found it effective for precipitation nowcasting. The use of Conv-LSTM would lead to an integration of DA and AI with HPC. This presentation will include an overview of the BDA project toward a DA-AI-HPC integration under the new AIP Acceleration Research scheme, and recent progress of the project.
Diurnal and Seasonal Variations of Sensible and Latent Heat Fluxes at an Agricultural Site in Ile-Ife, Southwest Nigeria
Authors: Ajao Adewale , Obisesan Omodara , Ayoola Muritala , Jegede Oluwagbemiga
Published: March 2020

Diurnal and seasonal variations of sensible heat (H) and latent heat (LE) fluxes observed at an agricultural site on the campus of Obafemi Awolowo University, Ile-Ife, southwest Nigeria have been reported in this paper. The deductions are made based on half-hourly flux data acquired from an open-path eddy covariance (OPEC) system measured continuously over a two-year observation period (2017-2018) at the study site. The study area is within tropical wet and dry climate of West Africa, thereby experiencing an alternating wet (that is, April – October) and dry (that is, December – February) seasons (monsoonal). Our results showed that peak hourly values of H and LE occurred at about 13:00 LT and 14:00 LT respectively, a lag of approximately one hour between them at the location. The diurnal range for H and LE during wet season was 75.3 W m-2 and 177.0 W m-2 respectively, while for dry season it was 182.0 W m-2 and 89.9 W m-2 respectively. The daily mean value of H for wet season was 19.7 ± 27.2 W m-2 and it was 52.1 ± 63.5 W m-2 for LE. For dry season, daily mean values for H and LE were 44.0 ± 66.4 W m-2 and 26.6 ± 33.7 W m-2 respectively. A transition of seasons from wet (Bowen ratio, Bo < 1) to dry (Bo > 1) was observed in November and reversal in March.

 

Keywords: Diurnal and Seasonal Variations, Sensible and Latent Heat Fluxes, Tropical Wet and Dry Climate
A Case Study of Severe Precipitation Caused by Meiyu Front in Northwest Taiwan
Authors: Hou Jou Ping , Su Li Zhen , Liao Yi Hao
Published: March 2020

From May to June in Southeast Asia, the cold high pressure on the mainland gradually weakens and the Pacific high pressure gradually increases. These two cold and warm pressure systems will form confrontations near Taiwan and South China. The stable "front" system is called "Meiyu front" in Taiwan. In previous studies, when the Meiyu front passed, it had the opportunity to converge with the prevailing wind field in front of the terrain in the northwestern part of Taiwan, resulting in a fast-moving airflow and the intensity of the jet, which is usually concentrated in the lower layers. It is therefore called a low-level jet. Low-level jets under certain conditions, known as barrier jets, can cause severe rainfall in northern Taiwan when they occur. The results of this study show that in the early morning of June 2, 2017, the Meiyu front approached northern Taiwan. When the main body of the front moved toward the Snow Mountain Range in northern Taiwan, a barrier jet appeared at an altitude of about 1 km. After the emergence of the barrier jets, sever precipitation occurred in Keelung and the northern coast of Taiwan in just 12 hours. Our research found that the emergence of barrier jets resulted in the increase of temperature gradients and vertical velocities in local areas; horizontal vortex tubes were twisted in the vicinity, and the horizontal wind shear on both sides of the jets enhanced the cyclonic circulation above the jets. And through the non-adiabatic effect, the stability of the release part was caused, resulting in a severe precipitation event in northern Taiwan. In this study, the observation data and model simulation results are compared with each other to analyze the main cause and physical mechanism of the severe precipitation in the northwest region in this case, and then to infer the dynamic and thermal processes of such weather phenomena over time.
Impact of solar cycle variation of UV radiation in the Northern Hemisphere winter polar troposphere
Authors: Song In-Sun , Kim Jeong-Han , Jee Geonhwa
Published: March 2020

Solar cycle (SC) induces variations in the UV radiation. The UV variations change the ozone production rate in the middle atmosphere. Responses to the SC-induced variations occur mainly in the equatorial upper stratosphere and the lower mesosphere. It has been reported that zonal mean temperature difference is 1--2 K between solar maximum and minimum. The temperature variation in the equatorial upper stratosphere modifies the meridional temperature gradient between the equatorial region and winter polar region. Change in the temperature gradient induces difference in the strength of the stratospheric polar vortex, which accompanies change in poleward meridional mass circulations and as a result change in the horizontal distribution of the sea-level pressure (SLP) in the winter polar region. In the present study, this mechanism of SC-induced SLP variations in the Northern Hemisphere (NH) winter polar regions is examined using an idealized whole-atmosphere general circulation model. This global model covers from the ground to the lower thermosphere and includes gravity wave drag parameterization and realistic topography. This idealized model is driven by the zonally-averaged radiative equilibrium temperature, but it nevertheless simulates quite realistically atmospheric variabilities such as sudden stratospheric warmings and quasi-biennial oscillations. Perpetual January simulations for solar maximum and minimum show that this idealized model can reproduce the negative SLP anomaly in the NH polar regions in solar maximum, but the magnitude of the anomaly is weak compared with reanalysis studies. Mechanisms of this SLP anomaly are examined through planetary wave dynamics and gravity-wave processes.
Modeling study on the polar middle atmospheric responses to medium energy electron (MEE) precipitation
Authors: Lee Ji-Hee , Song In-Sun , Jee Geonhwa
Published: March 2020

Energetic particle precipitation (EPP) is an important source of chemical changes in the polar middle atmosphere during winter. Recently, it has been suggested from modeling study that EPP-induced chemical changes can cause dynamic changes of the atmosphere. In this study we investigate the atmospheric responses to medium-to high energy electron (MEE) precipitations during 2005-2013 by using Specific Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). Results show that MEE precipitations significantly increase the amount of NOx and HOx, resulting in mesospheric and stratospheric ozone depletions during polar winter. The ozone depletion due to MEE precipitation induces warming in the polar lower mesosphere. Large ozone loss in the polar middle atmosphere leads to clear dynamic impacts, which causes warming by 3-11 K temperature increase and weakening of the zonal wind in the lower mesosphere. Our study show that the MEE precipitation induces not only the chemical effects such as ozone depletion but also clear dynamic effects in the polar middle atmosphere.
Assessment of flood effect on semi-arid special investment region using 1D hydrodynamic modeling
Authors: Yadav Sanjay , Borana Surendra , Jariwala Namrata , Chaurasia Shri Ram
Published: March 2020

The present study evaluates floods of semi-arid region with flat topography. The flood water spread over hundreds of square kilometer being delta region of Sukhbhadar River. The government of Gujarat aims to develop study region which spreads over 920 sq. km as Dholera Special Investment Region (DSIR). The study area is highly prone to flooding due to confluence of number of rivers namely Sukhbhadar, Lilka, Utavli and Padalio and tidal ingress from Gulf of Cambay.

Sukhbhadar River enters the DISR area near village Kashindra and flows through the Town Planning Scheme -TP1 and one of its tributaries Adhiya River, originating from village Cher flows through the Town Planning Scheme - TP2 of DSIR and meets the Sukhbhadar River at village Khun. The Sukhbhadar River is one of the major river passing through TP1 and TP2. The Sukhbhadar Dam is one of the major Dam on the Sukhbhadar River and it is approximately 100 km upstream of the study area. The average annual rainfall on the downstream side of the Dam and of DSIR region is 701 mm. In the year 2019 August there was heavy rainfall. The releases from the Sukhbhadar Reservoir and rainfall resulted into catastrophic floods in these regions of DSIR. As DSIR is special region proposed to develop for industrial activities, floods may cause millions of dollars damages in future. In the present study 1- Dimensional Hydrodynamic modelling has been carried out for recent flood of year 2019. MIKE 11 software is used to model 1D unsteady flow for this event. The shape file of the Sukhbhadar River reach from Sukhbhadar Dam to DSIR region is given as input and cross sections at regular interval of 100 m are generated from AW3D30 DEM. Sukhbhadar Dam release hydrograph is given as upstream boundary condition and predicted Tidal data of Bhavnagar is given as downstream boundary condition. It has been observed that from Sukhbhadar Dam to 55481.3 chainage slope is 1 in 698. For 55481.3 to 1611.33 chainage the slope is 1 in 3591. The area of DSIR is almost flat. As observed during recent flood of year 2019, entire DSIR area (920 sq km) was fully inundated. It has been felt that strong mitigation measures are required to cope up with these flooding situations. In the present analysis embankment or retaining wall on either bank of the river has been considered as one of the flood mitigation measure. The height of retaining wall to prevent these DSIR areas vary from 1 m to 25 meters up to 2500 cumec releases from the dam. This solution may not be economical hence it is proposed to take advantage of parallel natural streams and ponds to conserve flood water. This solution seems to be more practical and economical. The paper analyze flood of DSIR region as without proper flood measures it is difficult to develop this region.
Effect of ISO-SSE Interaction on the Rapid intensification of TS in the WNP Since the Late 1990s
Authors: Hong Chi-Cherng , Tsou Chih-Hua , Chen Kuan-Chieh , Chang Chi-Chun
Published: March 2020

This study addressed the abrupt increase in the development speed of Tropical storms (TSs) to severe TSs ( Category 3, referred to as STS) in the western North Pacific (WNP) during the late 1990s. Although the annual mean number of TSs in the WNP exhibited an abrupt decrease in the late 1990s, the annual mean number of STs did not exhibit significant change. This caused the ratio of annual mean number of STSs to the total TSs number displayed an abrupt increase in the late 1990s. Our observations indicate that the mean lifetime of a STS during the post 1990s period was approximately 70 hours shorter than that in the pre-1990s period because of the northwestward shift of the mean TS genesis location in response to the mega-La Niña-like mean state change in the late 1990s. This indicated that the TSs have developed into STSs with a faster speed since the late 1990s. The eddy kinetic energy budget of synoptic-scale eddy (SSE) indicated that the enhancement of scale interaction of intraseasonal oscillation (ISO)−SSE played a critical role in accelerating the TS–to–STS development. A further diagnosis revealed that the increase of ISO–SSE interaction was attributed to the mega–La Niña–like mean state change. The mega–La Niña–like associated anticyclone anomaly and warm oceanic condition in the WNP substantially modified the mean TS genesis location (northwestward shift), enhanced the ISO magnitude, and shifted the ISO propagation northward, thereby amplifying the ISO–SSE interaction in the WNP in the late 1990s.

Key words: Tropical storm, abrupt increase,  Intraseasonal oscillation (ISO), ISO–SSE interaction
Coherent emission driven by energetic ring-beam electrons in the solar corona
Authors: Zhou Xiaowei , Munoz Sepulveda Patricio , Buechner Joerg , Liu Siming
Published: March 2020

We analyzed properties of waves excited by mildly relativistic electron beams propagating along magnetic field with a ring-shape perpendicular momentum distribution in neutral and current-free solar coronal plasmas. These plasmas are subject to both the beam and the electron cyclotron maser (ECM) instabilities driven by the positive momentum gradient of the ring-beam electron distribution in the directions parallel and perpendicular to the ambient magnetic field, respectively. To explore the related kinetic processes self-consistently, 2.5-dimensional fully kinetic particle-in-cell (PIC) simulations were carried out.

To quantify excited wave properties in different coronal conditions, we investigated the dependence of their energy and polarization on the ring-beam electron density and magnetic field. In general, electrostatic waves dominate the energetics of waves and nonlinear waves are ubiquitous. In weakly magnetized plasmas, where the electron cyclotron frequency ωce is lower than the electron plasma frequency ωpe, it is difficult to produce escaping electromagnetic waves with frequency ω > ωpe and small refractive index ck/ω < 1 (k and c are the wavenumber and the light speed, respectively). Highly polarized and anisotropic escaping electromagnetic waves can, however, be effectively excited in strongly magnetized plasmas with ωce/ωpe ≥ 1. The anisotropy of the energy, circular polarization degree (CPD), and spectrogram of these escaping electromagnetic waves strongly depend on the number density ratio of the ring-beam electrons to the background electrons. In particular, their CPDs can vary from left-handed to right-handed with the decrease of the ring-beam density, which may explain some observed properties of solar radio bursts (e.g., radio spikes) from the solar corona.
Investigation of rainfall-induced failure processes and characteristics of wedge slopes using physical models
Authors: Lo Chia-Ming , Chu Chen-Han , Su Yi-Xiang
Published: March 2020

In this study, the small-scale physical modeling tests have considered the impact of the infiltration of rainfall in order to investigate the processes involved in wedge slope deformation and failure. We are conducted under controlled conditions of the intersection angle and half wedge angle. Observations obtained during each stage of deformation and failure were used to explain how gravity deformation varies on wedge slopes, and infer how rainfall influence slope failure. The results indicate that half wedge angle is a crucial factor in the deformation failure of slopes. The failure mechanisms of low intersection angle slopes (sliding model) differ considerably from those of high intersection angle slopes (free falling or toppling model). The infiltration of surface water can have a significant influence on rock layer deformation and the speed of failure. Details of the failure characteristics of wedge slope models are discussed in this paper.

Keywords: physical modeling, rainfall, wedge slope, the intersection angle, half wedge angle.
Structure of the Gare Kakheti foothills using seismic reflection profiles: implications for kinematic evolution of the Georgian part of Kura foreland fold-and-thrust belt
Authors: Razmadze Alexander
Published: March 2020

Gare Kakheti foothills are located between Lesser Caucasus and Kakheti Ridge and are mainly represented by the series of NEN dipping thrust faults, most of which are associated with fault‐related folds. Gare Kakheti foothills as a part of the Kura foreland fold-and-thrust belt developed formerly as a foreland basin (Oligocene-Lower Miocene) (e.g. Alania et al., 2017). Neogene shallow marine and continental sediments in the Gare Kakheti foothills keep the record on the stratigraphy and structural evolution of the study area during the compressive deformation. Interpreted seismic profiles and structural cross-sections across the Udabno, Tsitsmatiani, and Berebisseri synclines show that they are thrust-top basins. Seismic reflection data reveal the presence of growth fault-propagation folds and some structural wedges (or duplex). The evolution of the Udabno, Tsitsmatiani, and Berebisseri basins is compared with simple models of thrust-top basins whose development is controlled by the kinematics of competing for growth anticlines. Growth anticlines are mainly represented by fault-propagation folds. The geometry of growth strata in associated footwall synclines and the sedimentary infill of thrust-top basins provide information on the thrusting activity in terms of location, geometry, and age.
This work was supported by Shota Rustaveli National Science Foundation (SRNSF - #PHDF-19-268).

 
Yield and shear of rough interlocked faults: analytical solution and experimental observations
Authors: Sagy Amir , Lyakhovsky Vladimir , Hatzor Yossef H.
Published: March 2020

Natural fault surfaces are interlocked, partly cohesive, and display multiscale geometric irregularities. Here we examine the nucleation of deformation and the evolution of shear in such interlocked surfaces using a closed-form analytical solution and a series of laboratory experiments.  The analytical model considers an interlocked interface with multiscale roughness between two linear elastic half-space blocks. The interface geometry is based on three-dimensional fault surfaces imaging. It is represented by a Fourier series and the plane strain solution for the elastic stress distribution is represented as a sum of the constant background stress generated by a uniform far-field loading and perturbations associated with the interface roughness. The model predicts the critical stress necessary for failure and the location of failure nucleation sites across the surface, as function of the initial surface geometry.

A similar configuration is adopted in laboratory experiments as carbonate blocks with rough interlocked surfaces generated by tensional fracturing are sheared in a servo-controlled direct shear apparatus. Resistance to shear and surface roughness evolution are measured under variable normal stresses, slip distances and slip rates.  We find that the evolution of surface morphology with shear is closely related to the loading configuration. Initially rough, interlocked, surfaces become rougher when normal stress and displacement rate are increased. Under a fixed, relatively low normal stress and fixed displacement rate however, the surfaces become smoother with increasing displacement distance.  

The shear of the interlocked slip surfaces is associated with volumetric deformation, wear and frictional slip, all of which are typically observed across natural fault zones. We suggest that their intensities and partitioning are strongly affected by the initial surface roughness characteristics, the background stress, and the rate and magnitude of shear displacement. 