Kozo Yamashita
Tohoku University
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Publication
Featured researches published by Kozo Yamashita.
society of instrument and control engineers of japan | 2008
Masaki Yano; Kozo Yamashita; Y. Ida; M. Hayakawa; A. P. Nickolaenko
The observation at Moshiri (Hokkaido), Japan of ELF transmitter signals (~82 Hz) from a Russian transmitter has been described. The detection and identification, wave characteristics. etc. have been analyzed by using the ELF waveform data at Moshiri(two horizontal magnetic fields and one vertical electric field), which are subjected to the conventional FFT (fast Fourier transform) analysis, Nuttal filter etc. The wave characteristics at Moshiri at a distance (~6 Mm) from the transmitter, are compared with those near the anti-podal points, in order to compare with the ELF full-wave propagation theory.
ursi general assembly and scientific symposium | 2014
Yukihiro Takahashi; Mitsuteru Sato; Kozo Yamashita
Summary form only given. It has been recognized that lightning activity is an excellent proxy of atmospheric circulation in thunderstorm. GEON, the global ELF observation network, is the first continuously-operated lightning observation network covering while globe with uniform sensitivity for charge moment change. Here we show that in the period from February to June 2004 the variation of the number of lightning strokes in Asia Maritime Continent (hereinafter: MC) shows one-month oscillation clearly correlated with Outgoing Longwave Radiation (OLR) in Western Pacific Warm Pool (hereinafter: WPWP) with amplitudes of few 10s of percent but without apparent phase shift. In other words, when the thunderstorm activity in MC is enhanced, the OLR in WPWP becomes large, namely, less cloudy. Moreover, OLR in most part of other tropical region, such as those in Africa, Pacific Ocean and Atlantic Ocean, shows prominent negative correlation with the number of lightning strokes in MC, implying the activities of thunderstorms in tropical regions oscillate in the same phase. It was also found that such global oscillation seems to be synchronized with parameters that reflect solar activity, such as galactic cosmic ray or F10.7 index, but shifted by about 8 days. These results are probably related to the phenomena reported by Takahashi et al. (ACP in 2010), namely, a 27-day variation of OLR in WPWP, which is only seen in the solar maximum years of the 11-year cycle, for 3 cycles.
Quarterly Journal of the Royal Meteorological Society | 2010
Earle R. Williams; Walter A. Lyons; Y. Hobara; Vadim Mushtak; N. Asencio; R. Boldi; József Bór; Steven A. Cummer; Eran Greenberg; Masashi Hayakawa; Robert H. Holzworth; V. Kotroni; Junfei Li; C. Morales; Thomas E. Nelson; Colin Price; B. Russell; Mitsuteru Sato; Gabriella Sátori; K. Shirahata; Yukihiro Takahashi; Kozo Yamashita
Journal of Atmospheric and Solar-Terrestrial Physics | 2007
Y. Matsudo; Tomoyuki Suzuki; Masashi Hayakawa; Kozo Yamashita; Yoshiaki Ando; Koichiro Michimoto; Valery Korepanov
Natural Hazards and Earth System Sciences | 2008
M. Hayakawa; A. P. Nickolaenko; M. Sekiguchi; Kozo Yamashita; Y. Ida; M. Yano
Geophysical Research Letters | 2011
Y. Tanaka; M. Hayakawa; Y. Hobara; A. P. Nickolaenko; Kozo Yamashita; Mitsuteru Sato; Yukihiro Takahashi; T. Terasawa; Tadayuki Takahashi
Journal of Geophysical Research | 2011
Kozo Yamashita; Yukihiro Takahashi; Mitsuteru Sato; Hiromi Kase
Journal of Geophysical Research | 2012
Hiroyo Ohya; Fuminori Tsuchiya; Hiroyuki Nakata; K. Shiokawa; Yoshizumi Miyoshi; Kozo Yamashita; Yukihiro Takahashi
Journal of atmospheric electricity | 2009
Kozo Yamashita; T. Otsuyama; Y. Hobara; M. Sekiguchi; Y. Matsudo; M. Hayakawa; Valery Korepanov
Transactions of The Japan Society for Aeronautical and Space Sciences, Space Technology Japan | 2010
Kazuya Yoshida; Yukihiro Takahashi; Yuji Sakamoto; Eriko Ujiie; Kei Takiuchi; Yasuhiro Nakazato; Tomoki Sawakami; Takeshi Sakanoi; Yasumasa Kasaba; Satoshi Kondo; Kozo Yamashita; Shinya Ueda; Takeshi Takashima; Kazuhiro Nakazawa; Takefumi Mitani; Teruaki Enoto; Mitsuteru Sato; U. S. Inan; Ivan R. Linscott; Fredrik Bruhn; Yoshinari Masumoto