Toshiki Shimbori
Japan Meteorological Agency
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Publication
Featured researches published by Toshiki Shimbori.
Journal of Environmental Radioactivity | 2015
Kazuo Saito; Toshiki Shimbori; Roland R. Draxler
The World Meteorological Organization (WMO) convened a small technical task team of experts to produce a set of meteorological analyses to drive atmospheric transport, dispersion and deposition models (ATDMs) for the United Nations Scientific Committee on the Effects of Atomic Radiations assessment of the Fukushima Daiichi Nuclear Power Plant (DNPP) accident. The Japan Meteorological Agency (JMA) collaborated with the WMO task team as the regional specialized meteorological center of the country where the accident occurred, and provided its operational 5-km resolution mesoscale (MESO) analysis and its 1-km resolution radar/rain gauge-analyzed precipitation (RAP) data. The JMAs mesoscale tracer transport model was modified to a regional ATDM for radionuclides (RATM), which included newly implemented algorithms for dry deposition, wet scavenging, and gravitational settling of radionuclide aerosol particles. Preliminary and revised calculations of the JMA-RATM were conducted according to the task teams protocol. Verification against Cesium 137 ((137)Cs) deposition measurements and observed air concentration time series showed that the performance of RATM with MESO data was significantly improved by the revisions to the model. The use of RAP data improved the (137)Cs deposition pattern but not the time series of air concentrations at Tokai-mura compared with calculations just using the MESO data. Sensitivity tests of some of the more uncertain parameters were conducted to determine their impacts on ATDM calculations, and the dispersion and deposition of radionuclides on 15 March 2011, the period of some of the largest emissions and deposition to the land areas of Japan. The area with high deposition in the northwest of Fukushima DNPP and the hotspot in the central part of Fukushima prefecture were primarily formed by wet scavenging influenced by the orographic effect of the mountainous area in the west of the Fukushima prefecture.
Journal of Applied Volcanology | 2015
Yoshihiko Hasegawa; Akira Sugai; Yosuke Hayashi; Yuta Hayashi; Shoji Saito; Toshiki Shimbori
Since March 2008, the Japan Meteorological Agency (JMA) has operated a Volcanic Ash Fall Forecast (VAFF) system to issue forecasts of areas in Japan where ash falls are expected following volcanic eruptions. The hazardous effects of ash falls vary according to the quantity of ash generated and have different consequences for agriculture, communication and transport networks, and buildings. The prediction techniques based on the JMA Regional Atmospheric Transport Model were recently revised by the Meteorological Research Institute of JMA to allow predictions of the quantity and areas of ash fall, and areas to be affected by lapilli fall. JMA plans further improvements to the VAFF system to address the needs of people living near active volcanoes and to take into account expert advice in fields such as volcanology, disaster prevention, and broadcasting and medical services. The improved VAFF system will provide three types of information: a regular information before possible eruption, a brief preliminary forecast issued 5–10 minutes after an eruption, and a full forecast issued 20–30 minutes after an eruption. JMA has developed a table to accompany VAFFs that categorizes the hazardous effects for people according to various quantities of ash fall, and provides advice on preparedness measures and actions to be taken when an ash fall occurs. The new VAFF system will also provide predictions of areas of expected lapilli fall. JMA will start operation of the new VAFF system in spring 2015.
Earth, Planets and Space | 2014
Tomofumi Kozono; Hideki Ueda; Toshiki Shimbori; Keiichi Fukui
Multiple observations of subsurface and surface phenomena during volcanic eruptions provide important information about eruption styles, eruption column dynamics, and magma plumbing systems. During the 2011 eruptions of Kirishima-Shinmoe-dake volcano in Japan, borehole-type tiltmeter data and weather radar data captured the subsurface and surface phenomena, respectively; the tiltmeters detected deflation of a magma chamber caused by migration of magma to the surface, and the weather radar detected changes in the height of the eruption cloud echo. In this study, we present a method based on the correlation between magma chamber deflation and cloud echo height to identify eruption styles. The method can detect whether a column-forming eruption is accompanied by magma migration from the magma chamber (e.g., sub-Plinian eruption), or not (e.g., Vulcanian explosion). By using well-correlated chamber deflation and echo height data, we found that eruption column dynamics during the Shinmoe-dake eruptions are well described by a one-quarter power scaling relationship between cloud height and magma discharge rate, and that a clear correlation between geodetic volume change of the magma chamber and the erupted volume indicates a stable magma plumbing system connecting the magma chamber and the surface.
Earth, Planets and Space | 2014
Yoshiaki Fujiwara; Hitoshi Yamasato; Toshiki Shimbori; Takayuki Sakai
Since the caldera-forming eruption of Miyakejima Volcano in 2000, low-frequency (LF) earthquakes have occurred frequently beneath the caldera. Some of these LF earthquakes are accompanied by emergent infrasonic pulses that start with dilatational phases and may be accompanied by the eruption of small amounts of ash. The estimated source locations of both the LF earthquakes and the infrasonic signals are within the vent at shallow depth. Moreover, the maximum seismic amplitude roughly correlates with the maximum amplitude of the infrasonic pulses. From these observations, we hypothesized that the infrasonic waves were excited by partial subsidence within the vent associated with the LF earthquakes. To verify our hypothesis, we used the infrasonic data to estimate the volumetric change due to the partial subsidence associated with each LF earthquake. The results showed that partial subsidence in the vent can well explain the generation of infrasonic waves.
Journal of Environmental Radioactivity | 2015
Roland R. Draxler; D. Arnold; Masamichi Chino; Stefano Galmarini; Matthew C. Hort; Andy Jones; Susan Leadbetter; Alain Malo; Christian Maurer; Glenn D. Rolph; Kazuo Saito; Rene Servranckx; Toshiki Shimbori; Efisio Solazzo; Gerhard Wotawa
Sola | 2012
Akihiro Hashimoto; Toshiki Shimbori; Keiichi Fukui
Report of the Science Council of Japan, Sectional Committee on Nuclear Accident . Science Council of Japan, Sectional Committee on Nuclear Accident, 103 pp. | 2014
Pascal Bailly du Bois; Marc Bocquet; Dominique Boust; Igor Brovchenko; Anna Choe; Theo Christoudias; Damien Didier; Heiner Dietze; Pierre Garreau; Hironori Higashi; Kyung Tae Jung; Shinnichiro Kida; Philippe Le Sager; J. Lelieveld; Vladimir S. Maderich; Yasumasa Miyazawa; Soon-Ung Park; Denis Quélo; Kazuo Saito; Toshiki Shimbori; Yusuke Uchiyama; Peter F. J. van Velthoven; Victor Winiarek; Sachiko Yoshida
Papers in Meteorology and Geophysics | 2009
Toshiki Shimbori; Yuri Aikawa; Keiichi Fukui; Akihiro Hashimoto; Naoko Seino; Hitoshi Yamasato
Remote Sensing of Environment | 2016
Hiroshi Ishimoto; Kazuhiko Masuda; Keiichi Fukui; Toshiki Shimbori; Tomoyuki Inazawa; Hiroaki Tuchiyama; Kensuke Ishii; Toshiyuki Sakurai
Papers in Meteorology and Geophysics | 2014
Toshiki Shimbori; Reiko Kai; Yosuke Hayashi; Yuta Hayashi; Akira Sugai; Yoshihiko Hasegawa; Akihiro Hashimoto; Akimichi Takagi; Tetsuya Yamamoto; Keiichi Fukui