| Project/Area Number |
13136201
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
OGAWA Tadahiko Nagoya University, Solar-Terrestrial Environment Laboratory, Professor (60271607)
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| Co-Investigator(Kenkyū-buntansha) |
SHIOKAWA Kazuo Nagoya University, 太陽地球環境研究所, Associate Professor (80226092)
OTSUKA Yuichi Nagoya University, Solar-Terrestrial Environment Laboratory, Assistant Professor (40314025)
SAITO Akinori Kyoto University, Faculty of Science, Assistant Professor (10311739)
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| Project Period (FY) |
2001 – 2006
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥97,800,000 (Direct Cost: ¥97,800,000)
Fiscal Year 2006: ¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 2005: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2004: ¥20,900,000 (Direct Cost: ¥20,900,000)
Fiscal Year 2003: ¥18,000,000 (Direct Cost: ¥18,000,000)
Fiscal Year 2002: ¥24,400,000 (Direct Cost: ¥24,400,000)
Fiscal Year 2001: ¥23,500,000 (Direct Cost: ¥23,500,000)
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| Keywords | mesosphere / thermosphere / ionosphere / plasma bubble / traveling ionospheric disturbances / ionospheric irregularities / airglow / GPS / 赤道大気・プラズマ環境 / 赤道電離圏・熱圏・中間圏 / 熱圏大気光 / プラズマ・大気波動 / CCDカメラ / GPS衛星 / 国際情報交換 / インドネシア |
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| Research Abstract |
We have been conducted ground-based observations of the ionosphere and thermosphere in Indonesia, Japan, and Australia We paid special attention to 100-1000 km scale disturbances in the equatorial F-region ionosphere and thermosphere, i.e., medium-scale traveling ionospheric disturbances (MSTIDs) and plasma bubbles. MSTIDs detected with a 630-nm all-sky imager at Kototabang in Indonesia appear within and in the south of the equatorial F-region anomaly crest with a high occurrence in May and June, and have, on the average, a phase velocity of 300 m/s toward the south and a wavelength of 700 km. Plasma bubbles moving eastward at about 100 m/s have a scale of about 100 km with spacings of 200-250 km, and are embedded within plasma structures with an east-west scale of about 1000 km. MSTIDs and giant plasma bubbles can be simultaneously detected at lower midlatitudes in Japan and Australia that are connected by the geomagnetic field line, and are very identical in appearance in the both hemispheres. Equatorial ionospheric scintillations of GPS radio waves associated with plasma bubbles have been continuously monitored at Kototabang. They appear predominantly from sunset to midnight in equinoctial months, a characteristic of equatorial plasma bubble occurrences. To investigate possible dynamical coupling between the ionosphere/thermosphere and troposphere over the equator, we compare the scintillation activity and Earth's brightness temperature (Tbb) variation over the Indian Ocean. The results indicate the following: 1) the scintillation occurrence and Tbb variation are modulated by planetary waves with periods from a few days to several tens of days, and 2) the scintillation tend to be enhanced when high and low Tbb regions appear in the west of Kototabang, suggesting that plasma bubbles may be seeded by atmospheric gravity waves propagating upward from the troposphere.
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