1998 Fiscal Year Final Research Report Summary
Influence of meteors on the mesosphere studied by the cooperative radar/lidar
| Project/Area Number |
08454137
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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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 |
TSUDA Toshitaka Kyoto University, Radio Atmospheric Science Center, Professor, 超高層電波研究センター, 教授 (30115886)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAHARA Takuya Shinshu University, Faculty of Engineering, Research Associate, 工, 助手 (40273073)
YAMAMOTO Mamoru Kyoto University, Radio Atmospheric Science Center, Associate Professor, 助教授 (20210560)
NAKAMURA Takuji Kyoto University, Radio Atmospheric Science Center, Associate Professor, 超高層電波研究センター, 助教授 (40217857)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Mesopause / Meteor / Meteor Radar / Sodium Lidar / Airglow / Middle and Upper Atmosphere / Metallic Atom Layer / Sporadic Sodium Layer |
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| Research Abstract |
In this study, meteor trails have been observed by the MU radar of Kyoto University, in order to investigate meteor flux and mesospheric dynamical parameters. Simultaneous lidar and airglow imager observations have been carried out and results are compared, in order to clarify the mechanism of variations of constituents in the mesosphere and mesopause region. Especially, sporadic sodium layer is focused as one of the main targets. From plenty of simultaneous observations, the following findings have been revealed.
1. The meteor flux was not influenced by the major meteor stream activity, from the MU radar observation with a high sensitivity. However, if height, direction, or meteor echo strength is limited there could be a significant temporal variation.
2. The temporal variation of sodium density around the mesopause with slow downward progression with a period larger than several hours was confirmed to be inertia gravity waves.
3. The sporadic sodium layer was sometimes accompanied by localized temperature increase or wind shear. Especially, there was a strong correlation between the vertical shear of horizontal wind and occurrence of sporadic sodium layers. No significant correlation was found between the meteor flux and sporadic sodium layer.
4. During the cooperative observation of sodium lidar and airglow imager, atmospheric gravity events were frequently observed in the airglow layer by the imagers, which have clarified climatologies and structures of small scale gravity waves in the mesopause region.
5. Strong activity of bright Leonid meteors (fireballs) were observed by the MU radar about one day prior to the predicted meteor storm in November 1998. However, no significant influence on the mesopause region was found by the optical measurement.
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