1994 Fiscal Year Final Research Report Summary
Simultaneous Light-Radio Observations of Ionospheric E-region field-aligned irregularities
| Project/Area Number |
05452083
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
FUKAO Shoichiro Kyoto Univ.RASC Professor, 超高層電波研究センター, 教授 (30026249)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANAKA Manabu Kyoto Univ.RASC Lecturer, 超高層電波研究センター, 講師 (30183982)
FUKUNISHI Hiroshi Tohoku Univ.Faculty of Science Professor, 理学部, 教授 (90099937)
TSUDA Toshitaka Kyoto Univ.RASC Assistant Professor, 超高層電波研究センター, 助教授 (30115886)
YAMAMOTO Mamoru Kyoto Univ.RASC Research Associste, 超高層電波研究センター, 助手 (20210560)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Ionosheric E-region Irregularity / Field-aligned Irregularity / Spradic-E layr / MU Radar / Frequency Agile Radar / Imaging of Nightglow / Multicolor All-sky Imager / Mid-latitude Ionospherre |
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| Research Abstract |
Since 1989, the MU radar has been extensively utilized to reveal fine structures of the ionospheric E-region field-aligned irregularities (FAI). We found two types of FAI echoes in the E-region FAI.One is the quasi-periodic (QP) type which intermittently appears in the altitude region above 100 km in the summer months. The other is the continuous type which appear continuously in time in the altitude region of 90-100 km. Although the QP structure were thought to be generated by the atmospheric gravity waves, its generation mechanism were uncertain. In this study we have studied spatial structure of the E-region FAI by using the MU radar (Radio Atmospheric Science Center, Kyoto University), Frequency Agile Radar (FAR) (SRI International), and Multicolor Airglow Imaging System (MAIS) (Tohoku University). The FAR was located in Taga which is approximately 40 km north of the MU radar site. Simultaneous observation between the MU radar and FAR were conducted in the period from May 26,1993 until July 26,1993. The MAIS was located in Kiso observatory of Univ. Tokyo for this cooperative study in the same period. Results of this study is summarized as follows.
(1) From simultaneous observations between the MU radar and FAR,it was found that wavelike structures of the FAI horizontally propagated toward south-southwest or southwest. The echoing regions were elongated from northwest to the southeast.
(2) MAIS and other airglow observations revealed similar wavelike structures in the altitude region of 90-100 km.
(3) From the comparison between the radar observations and the ionosonde in Shigaraki, good correlation between the FAI and the sporadic-E layr was found.
(4) We have proposed a model that the QP structures of the FAI are generated by the polarization electric field which is produced by the altitude modulation of the sporadic-E layr by the atmospheric gravity waves.
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