NAKAMURA Takuji KYOTO UNIVERSITY, Ration Science Center for Space and Atmosphere, Associate Professor, 宙空電波科学研究センター, 助教授 (40217857)
HASHIGUCHI Hiroyuki KYOTO UNIVERSITY, Ration Science Center for Space and Atmosphere, Associate Professor, 宙空電波科学研究センター, 助教授 (90293943)
YAMAMOTO Mamoru KYOTO UNIVERSITY, Ration Science Center for Space and Atmosphere, Associate Professor, 宙空電波科学研究センター, 助教授 (20210560)
OTSUKA Yuichi Nagoya University, Solar Terrestrial Energy Laboratory, Research Associate, 太陽地球環境研究所, 助手 (40314025)
SAITO Akinori KYOTO UNIVERSITY, Faculty of Science, Research Associate, 理学研究科, 助手 (10311739)
Ionospheric irregularities in the mid-latitude E-region has been a study topics for more than ten years. The epoch was the discovery of the quasi-periodic (QP) structure in the E-region FAI (Field-Aligned Irregularity) echoes observed with the MU radar in Japan. The QP structures appear in the E-region FAI as a reflection of modulation pattern in the Sporadic-E (Es) layers. The structures are associated with polarization electric field, which suggests strong coupling process between the ionized and neutral atmosphere. In August 2002, we conducted SEEK-2 (Sporadic-E Experiment over Kyushu 2) campaign in Japan under collaboration with scientists from Japan, USA and Taiwan. The SEEK-2 consists of two sounding rockets of Institute of Space and Aeronautical Sciences that include in-situ experiment of electron density, electron temperature, electric field, plasma fluctuation and waves, and geomagnetic field as before. This research program is mainly dedicated to conduct the SEEK-2 ground-based observations. We operated two radars of 24.5 MHz and 31.6 MHz, ionosonde network of Japan, an MF radar, several airglow imagers, and a GPS scintillation-receiver system. We observed intense QP echoes with radars after 23 LT (= UT + 9 hours) on August 3, 2002, and launched rockets into the E-region at 2324 LT and 2339 LT. The operation of the SEEK-2 was very successful as we could, select a good event for the launches. All instruments on the rockets worked fine. We have found that the rockets detected multi-layered Es-layers at 103, 105 and 129 km altitudes, and intense electric fields that approach +-10 mV/m. In March 2003, we hosted the SEEK-2 workshop for data comparison and analysis. From this observation program we published more than 30 papers in the international journals. Numbers of oral presentations from the SEEK-2 results were 21 in international conferences, and 54 in domestic meetings.