| Co-Investigator(Kenkyū-buntansha) |
SHIOKAWA Kazuo Solar-Terrestrial Environment Laboratory, Nagoya University, Associate Professor, 太陽地球環境研究所, 助教授 (80226092)
NISHINO Masanori Solar-Terrestrial Environment Laboratory, Nagoya University, Associate Professor, 太陽地球環境研究所, 助教授 (70023679)
SHINAGAWA Hiroyuki Solar-Terrestrial Environment Laboratory, Nagoya University, Associate Professor, 太陽地球環境研究所, 助教授 (00262915)
NAKAMURA Takuji Radio Science Center for Space and Atmosphere, Kyoto University, Associate Professor, 宙空電波科学研究センター, 助教授 (40217857)
OTSUKA Yuichi Solar-Terrestrial Environment Laboratory, Nagoya University, Research Associate, 太陽地球環境研究所, 助手 (40314025)
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| Research Abstract |
1) Routine observation of airglow image has been started since July 2000 at Sata (Kagoshima) and since October 2001 at Darwin (Australia) during this research period. Together with Rikubetsu (Hokkaido) and Shigaraki (Siga) (since October 1998), these four stations continue taking airglow images. Campaign observations were carried out at Okinawa (August, 1999) and Tanegashima (August 2002). A Fabry-Perot interferometer (FPI) measures mesospheric and thermospheric wind since October 2000 at Shigaraki. Quick-look plots of these routine measurements are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/.
2) Results for gravity waves in the mesopause region : a) Climatology (occurrence, propagation directions, and so on) of gravity waves were obtained from statistical study of airglow images at these Japanese and Australian stations. b) Localized (isolated) structure was found in the mesopause region. We suggest that nonlinear wave-wave interactions caused this structure. c) Heights of gr
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avity waves and airglow emissions were determined by a triangulation technique using airglow images obtained at two nearby sites.
3) Results for medium-scale traveling ionospheric disturbance (MSTID) : a) Climatology (occurrence, wavelength, propagation directions, and so on) of MSTIDs were obtained from statistical study of airglow images in Japan. b) Based on a comparison of satellite data and model calculations including background wind information from FPI, we show that the MSTIDs are not directly caused by gravity waves, but correspond to the electric field structure generated by some ionospheric instability. c) Based on simultaneous airglow imaging observations in Japan and Australia, we found that this electric field structure propagates along magnetic field line between the two hemispheres.
4) Results for large-scale traveling ionospheric disturbance (LSTID) : LSTIDs were identified as 630-nm airglow enhancement during magnetic storms. We showed on the basis of model calculations and direct wind measurements that this LSTID was caused by poleward wind enhancement (propagating equatorward) in the thermosphere. We also argued from the observed auroral zone energy input that simple wind generation model in the auroral zone did not explain the observed LSTID features.
5) Based on the simultaneous airglow imaging observations in Japan and Australia, we found symmetric plasma bubble structures between the two hemispheres.
6) During the research period, we have succeeded observations of low-latitude aurora 11 times in the northern part of Japan (Hokkaido). Two of them were observed in the mainland of Japan (Shigaraki), making a record of lowest latitude of auroral measurement in Japan.
7) From simultaneous measurement of mesospheric wind by the FPI and the MU radar, temporal variations of airglow emission height were estimated. Less
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