Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.
Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06
We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.
Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.
Earth, Planets and Space (Internet), 71, p.9_1 - 9_10, 2019/01
Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of 10 keV.
Saito, Kimiaki; Kinase, Sakae; Fujisaki, Tatsuya*; Hiraoka, Takeshi*; Saito, Hidetoshi*; Tsuda, Shuichi; Sato, Kaoru; Takashima, Fusao*
Hoken Butsuri, 41(3), p.158 - 168, 2006/09
no abstracts in English
Takeshita, Kenji*; Takashima, Yoichi*; Matsumoto, Shiro*; Inami, Shinichi
Journal of Nuclear Science and Technology, 32(9), p.941 - 943, 1995/00
Iimoto, Takeshi*; Maedera, Ikuhiko*; Nunokawa, Jun*; Matsuzawa, Hajime*; Kurokawa, Sumihiko*; Yanagawa, Yukihide*; Someya, Seiichi*; Hashimoto, Makoto; Seya, Natsumi; Okawa, Yasuhisa; et al.
no journal, ,
no abstracts in English
Sato, Tatsuhiko; Ishii, Mamoru*; Kataoka, Ryuho*; Kubo, Yuki*; Minoshima, Takashi*; Miyoshi, Yoshizumi*; Nagamatsu, Aiko*; Shiota, Daiko*; Takashima, Takeshi*; Yasuda, Hiroshi*
no journal, ,
Forecast of radiation doses for astronauts as well as aircrews due to the exposure to solar energetic particles (SEP) is one of the greatest challenges in space weather research. In last 5 years, we have developed a WArning System for AVIation Exposure to Solar energetic particles: WASAVIES. In this system, the SEP fluxes incident to the atmosphere are calculated by physics-based models, and they are converted to radiation doses using a database developed on the basis of air-shower simulation. However, it takes approximately 2.5 hours to determine the parameters used in the physics-based models after the detection of GLEs, and thus, the current WASAVIES cannot predict doses during the peak of GLEs. Therefore, we are trying to reduce the time for evaluating the parameters, as well as to develop a nowcast system for the radiation dose due to SEP exposure, under the framework of Project for Solar-Terrestrial Environment Prediction (PSTEP) in Japan. A brief outline of WASAVIES together with our future strategy will be presented at the meeting.