HR: 1330h
AN: AE42A-0800    [PDF]
TI: The Structure of Sporadic-E Layer Suggested by the In-situ Electron Number Density Profile Obtained During the SEEK-2 Campaign
AU: * Wakabayashi, M
EM: waka@stpp1.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AU: Ono, T
EM: ono@stpp1.geophys.tohoku.ac.jp
AF: Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578 Japan
AB: To understand the generation mechanism of QP echoes, the SEEK-2 campaign was carried out on August 3, 2002. It has been planned as an in-situ observation using two sounding rockets and ground-based instruments. Based on the electron number density measured by using the Impedance Probe during the rocket experiments, there have been found very similar peak structures of electron density in each profile. This similarity might be an important signature to understand the generation mechanism of QP echoes. It is also suggested that there was significant horizontal modulation of electron number density at the altitude of Es layer, suggested by comparison of Impedance Probe and Beacon observation results. The 3-D structure of Es layer is very important to understand the process of QP echoes generation, however there were few studies on the 3-D picture of Es layers. The purpose of this paper is to discuss on the possibility to realize the 3-D Es structure mentioned above. NEI(Number density of electrons by Impedance probe) was installed in S310-31 and 32 sounding rockets which were used during the SEEK-2 campaign, they launched at 23:24JST and 23:39JST respectively. The altitude profiles obtained by the measurement of electron number density showed very sharp peak due to the Es layer at the altitude of around 105km (number density is about 10$^5$ /cc). This feature is very similar among the four profiles, so it is possible to infer that there is very large structure horizontally expanded more than 100km. In addition, there are large modulation of electron number density in the Es layer suggested by the comparison between NEI and Beacon measurement. The estimated magnitude of the modulation is ranging from 10$^5$ to 10$^4$ /cc. Based on these facts, it becomes possible to estimate the 3-D structure of Es layer. About 3-D structure of Es layer estimated by radar observation results have already reported in several issues, as an example, [Chu, Yen-Hsyang et al., 2002]. In this paper, 3-D structure of Es layer estimated by in-situ observation result is discussed by comparing to the other results obtained during SEEK-2 or theoretical studies of QP echoes generation [R. B. Cosgrove et al., 2001], and recent progress of study on the irregular structure of Es layer.
DE: 2400 IONOSPHERE
DE: 2443 Midlatitude ionosphere
DE: 2467 Plasma temperature and density
DE: 2471 Plasma waves and instabilities
DE: 2487 Wave propagation (6934)
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting