Time filter

Source Type

Shimura T.,Disaster Prevention Research Institute | Mori N.,Disaster Prevention Research Institute | Takemi T.,Disaster Prevention Research Institute | Mizuta R.,Meteorological Research InstituteTsukuba Japan
Journal of Geophysical Research: Oceans | Year: 2017

Ocean surface waves can play an active role in climate systems, but they are often ignored in Global Climate Models (GCMs). Wave-dependent surface roughness was implemented within the Atmospheric GCM (MRI-AGCM) using the spectral wave model WAVEWATCH III. Two types of wave-dependent roughness, due to wave steepness and to wave age, were considered. Climate simulations with wave-dependent roughness were compared to simulations with just wind speed-dependent roughness. In climate simulation with wave steepness-dependent roughness, the spatial distribution of roughness is correlated to that of swell dominance. In simulation with wave age-dependent roughness, the spatial distribution of roughness is correlated to that of wind direction stationarity. Both simulations show reduced roughness in the tropics, which leads to an enhancement of surface wind speeds by up to 15%; these enhanced wind speeds are closer to observations compared with the baseline simulation with just wind speed-dependent roughness. We find that the reduced roughness and the enhanced wind speeds in the tropics lead to significant changes in atmospheric circulation, as in Hadley circulation and precipitation. The characteristic responses of the Hadley circulation and precipitation to changing sea surface roughness are presented. © 2017. The Authors.


VIDEO:  Researchers use special simulations to study tornado debris and how it interacts with deadly tornadoes. view more Researchers have developed the first numerical polarimetric radar simulator to study and characterize the scattering of debris particles in tornadoes. (See video) The results of their study are published in the Institute of Electrical and Electronics Engineers (IEEE) journal Transactions on Geoscience and Remote Sensing. "These results are important for operational weather forecasters and emergency managers," says Nick Anderson, program director in the National Science Foundation's (NSF) Division of Atmospheric and Geospace Sciences, which funded the research. "An improved understanding of what weather radars tell us about tornado debris can help provide more accurate tornado warnings and quickly direct emergency personnel to affected areas." Current polarimetric radars, also called dual-polarization radars, transmit radio wave pulses horizontally and vertically. The pulses measure the horizontal and vertical dimensions of precipitation particles. The radars provide estimates of rain and snow rates, accurate identification of the regions where rain transitions to snow during winter storms, and detection of large hail in summer thunderstorms. But polarimetric radars have limitations the new research aims to address. "With this simulator, we can explain in great detail to the operational weather community [weather forecasters] the tornadic echo from polarimetric radar," says Robert Palmer, an atmospheric scientist at the University of Oklahoma (OU) and co-author of the paper. Palmer is also director of the university's Advanced Radar Research Center. "The knowledge gained from this study will improve tornado detection and near real-time damage estimates." Characterizing debris fields in tornadoes is vital, scientists say, because flying debris causes most tornado fatalities. The researchers conducted controlled measurements of tornado debris to determine the scattering characteristics of several debris types, such as leaves, shingles and boards. The orientation of the debris, the scientists found, makes a difference in how it scatters and falls through the atmosphere -- and where it lands. Additional co-authors of the paper include OU's David Bodine, Boon Leng Cheong (lead author), Caleb Fulton, Sebastian Torres, and Takashi Maruyama of the Disaster Prevention Research Institute at Japan's Kyoto University. The paper's co-authors designed the field experiments in collaboration with atmospheric scientist Howard Bluestein of OU.


News Article | May 1, 2017
Site: www.eurekalert.org

IMAGE:  A University of Oklahoma research team with the Advanced Radar Research Center has developed the first numerical polarimetric radar simulator to study and characterize scattering mechanisms of debris particles in... view more A University of Oklahoma research team with the Advanced Radar Research Center has developed the first numerical polarimetric radar simulator to study and characterize scattering mechanisms of debris particles in tornadoes. Characterizing the debris field of a tornado is vital given flying debris cause most tornado fatalities. Tornado debris characteristics are poorly understood even though the upgrade of the nation's radar network to dual polarimetric radar offers potentially valuable capabilities for improving tornado warnings and nowcasting. "These results are important for operational weather forecasters and emergency managers," says Nick Anderson, program director in the National Science Foundation Division of Atmospheric and Geospace Sciences, which funded the research. "An improved understanding of what weather radars tell us about tornado debris can help provide more accurate tornado warnings, and quickly direct emergency personnel to affected areas." "With this simulator, we can explain in great detail to the operational weather community the tornadic echo from the polarimetric radar," said Robert Palmer, ARRC executive director. "The signal received by the dual polarimetric radar is not easily understood because rain is mixed with the debris. The knowledge we gain from this study will improve tornado detection and near real-time damage estimation." Numerous controlled anechoic chamber measurements of tornadic debris were conducted at the Radar Innovations Laboratory on the OU Research Campus to determine the scattering characteristics of several debris types--leaves, shingles and boards. Palmer, D.J. Bodine, B.L.Cheong, C.J. Fulton and S.M. Torres, the center, and the OU Schools of Electrical and Computer Engineering and Meteorology, developed the simulator to provide comparisons for actual polarimetric radar measurements. Before this study, there were many unanswered questions related to tornado debris scattering, such as knowing how the size, concentration and shape of different debris types affect polarimetric variables. How the radar identifies the debris is equally as important. Orientation of debris makes a difference as well as how the debris falls through the atmosphere. Overall, understanding debris scattering characteristics aid in the discovery of the relationship between debris characteristics, such as lofting and centrifuging, and tornado dynamics. OU team members were responsible for various aspects of this study. Coordination of damage surveys and collection of debris samples were led by Bodine. Field experiments were designed by team members in collaboration with Howard Bluestein, OU School of Meteorology. Electromagnetic simulations and anechoic chamber experiments were led by Fulton. The signal processing algorithms were developed by Torres and his team. Cheong led the simulation development team. The study, "SimRadar: A Polarimetric Radar Time-Series Simulator for Tornadic Debris Studies," will be published in the May issue of the Institute of Electrical and Electronics Engineers Transactions on Geoscience and Remote Sensing. This work is supported by the National Science Foundation with grant number AGS-1303685. There were significant results from the collaboration between the center and the Disaster Prevention Research Institute in Kyoto University. Note to editors: An animation has been developed for the simulation of the three types of tornadic debris used in this study, which included leaves (green), shingles (pink) and boards (orange). The OU team has the ability, however, to simulate other types of debris. Download the animation at https:/ .


Zhusupbekov A.Zh.,L.N.Gumilyov Eurasian National University | Alibekova N.T.,L.N.Gumilyov Eurasian National University | Abilmazhenov T.,L.N.Gumilyov Eurasian National University | Morev I.,L.N.Gumilyov Eurasian National University | And 4 more authors.
14th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering | Year: 2011

At present the estimation of geological conditions of territory is impossible without geoinformation technologies. Technologies of geo-information system (GIS) are widely used for engineering-geological mapping, planning of development of territories, the forecast of dangerous natural processes, an estimation of various risks. All similar works are based on the control system of databases of the geological information which allow to receive the new information by modeling geotechnical properties of soils. To estimate engineering-geological conditions on the built-up territory of the city our Japanese colleagues of geotechnics and we have created the first Geoinformation database program based on the materials of geological engineering surveys on the projects of Astana city which allowed to analyze the regional conditions of soils prior to a detailed research.


Moya A.,Disaster Prevention Research Institute | Moya A.,University of Costa Rica | Irikura K.,Disaster Prevention Research Institute | Irikura K.,Aichi Institute of Technology
Computers and Geosciences | Year: 2010

We present a velocity model inversion approach using artificial neural networks (NN). We selected four aftershocks from the 2000 Tottori, Japan, earthquake located around station SMNH01 in order to determine a 1D nearby underground velocity model. An NN was trained independently for each earthquake-station profile. We generated many velocity models and computed their corresponding synthetic waveforms. The waveforms were presented to NN as input. Training consisted in associating each waveform to the corresponding velocity model. Once trained, the actual observed records of the four events were presented to the network to predict their velocity models. In that way, four 1D profiles were obtained individually for each of the events. Each model was tested by computing the synthetic waveforms for other events recorded at SMNH01 and at two other nearby stations: TTR007 and TTR009. © 2010 Elsevier Ltd.


Tanaka T.,Disaster Prevention Research Institute
Fire Safety Journal | Year: 2012

Various types of fires occurred following the Great East Japan Earthquake on 11 March, 2011 in extensive areas across the Tohoku and Kanto districts. It was, of course, difficult for a limited number of fire researchers to thoroughly investigate the fires, which were distributed over extremely wide areas. Nevertheless, it was necessary to make the investigations before the fire scenes had been lost with time. A joint effort was made by people from universities, national research institutes and industries related with fire research and safety. Although it will take some more time before satisfactory results of the investigation are made public, this paper attempts to outline the peculiar features of the fires that have been revealed at this point. © 2012 Elsevier Ltd.


Goda K.,University of BristolBristol | Yasuda T.,Disaster Prevention Research Institute | Mori N.,Disaster Prevention Research Institute | Mai P.M.,Earth Science and Engineering
Journal of Geophysical Research C: Oceans | Year: 2015

The sensitivity and variability of spatial tsunami inundation footprints in coastal cities and towns due to a megathrust subduction earthquake in the Tohoku region of Japan are investigated by considering different fault geometry and slip distributions. Stochastic tsunami scenarios are generated based on the spectral analysis and synthesis method with regards to an inverted source model. To assess spatial inundation processes accurately, tsunami modeling is conducted using bathymetry and elevation data with 50 m grid resolutions. Using the developed methodology for assessing variability of tsunami hazard estimates, stochastic inundation depth maps can be generated for local coastal communities. These maps are important for improving disaster preparedness by understanding the consequences of different situations/conditions, and by communicating uncertainty associated with hazard predictions. The analysis indicates that the sensitivity of inundation areas to the geometrical parameters (i.e., top-edge depth, strike, and dip) depends on the tsunami source characteristics and the site location, and is therefore complex and highly nonlinear. The variability assessment of inundation footprints indicates significant influence of slip distributions. In particular, topographical features of the region, such as ria coast and near-shore plain, have major influence on the tsunami inundation footprints. © 2015. The Authors.


News Article | September 13, 2016
Site: news.yahoo.com

A Japanese volcano that last erupted in 1914 could be set to blow in the next few decades, new research suggests. The pool of liquid magma swelling beneath Sakurajima volcano is growing every year — a sign of a growing threat. "This big reservoir is growing, and it's growing at quite a fast rate," said study co-author James Hickey, a geophysical volcanologist at the University of Exeter's Camborne School of Mines in England. At the current rate, Sakurajima could erupt catastrophically in about 25 years, according to the study. The new analysis could also help scientists better forecast when other big volcanoes could erupt, the researchers said. [Raw Video: Volcano in Southern Japan Erupts] Sakurajima volcano, located on the southwestern edge of Japan's Kyushu island, last erupted in 1914, killing 58 people and causing a massive flood in the nearby seaside city of Kagoshima. Sakurajima is fed by a pool of magma lying beneath the subterranean Aira caldera, and the filling of this magma reservoir causes the volcano to have minor eruptions roughly every day. In the 1950s, scientists tried to quantify the risk of future eruptions at Sakurajima by using a simple model, assuming the Earth's surface above the volcano was flat and that the pool of magma was spherical. The model had a big advantage: "You can basically solve it with pen and paper," Hickey told Live Science. However, over the years, scientists realized that this ultrasimplified model did not match volcanic activity at Sakurajima. To better forecast eruptions at Sakurajima, Hickey and his colleagues developed a much more complicated computer model — one that incorporated the unique topography of the area surrounding the volcano. That model also took into account that the Earth's crust is made up of different layers, with different properties. Then, the team incorporated data from seismometers and highly precise GPS devices placed in and around the volcano. Those sensors revealed tiny changes in the Earth that were clues to the activity of the magma pool deep below. The researchers discovered that the reservoir of magma beneath the caldera was growing at a significant rate. From this model, they forecast that it would take 130 years from the past major eruption for the next one to occur — meaning the region is due for a major explosion around 2044. The new model was better at capturing past behavior at the volcano, the researchers reported today (Sept. 13) in the journal Scientific Reports. It also found that the pool of magma beneath the caldera looks more squashed and oblong than spherical, Hickey said. Volcanologists don't have a crystal ball, however, and the current forecast could be slightly off because they assume a constant growth rate for the magma pool. But if the daily eruptions were to increase to two or three times per day — releasing small amounts of that magma — that could offset the growth of the magma pool, which could delay a deadly eruption for a long time, Hickey said. And even with highly accurate models, volcanoes sometimes surprise experts. For instance, in 2014, Mount Ontake volcano in Japan erupted without warning, killing about 57 people. However, leaders in the region are already prepared for an eruption in the near term: The Kagoshima City Office prepared a new evacuation plan after an eruption scare in August 2015 prompted an evacuation crisis, study co-author Haruhisa Nakamichi, associate professor at the Disaster Prevention Research Institute, Kyoto University, said in a statement. Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Loading Disaster Prevention Research Institute collaborators
Loading Disaster Prevention Research Institute collaborators