2007 Fiscal Year Final Research Report Summary
Study of the variation of the thermosphere by equatorial atmospheric energy
| 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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| Keywords | mesosphere / thermosphere / ionosphere / plasma bubble / traveling ionospheric disturbances / ionospheric irregularities / airglow / GPS |
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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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[Journal Article] Development of airglow temperature photometers with cooled-CCD detectors2007
Author(s)
Shiokawa, K., Y. Otsuka, S. Suzuki, T. Katoh, Y. Katoh, M. Satoh, T. Ogawa, H. Takahashi, D. Gobbi, T. Nakamura, B. P. Williams, C. -Y. She, M. Taguchi, T. Shimomai
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Journal Title
Earth Planets Space 59
Pages: 585-599
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] GPS detection of total electron content variations over Indonesia and Thailand following the 26 December 2004 earthquake2006
Author(s)
Otsuka, Y., N. Kotake, T. Tsugawa, K. Shiokawa, T. Ogawa, Effendy, S. Saito, M. Kawamura, T. Maruyama, N. Hemmakorn, T. Komolmis
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Journal Title
Earth Planets Space 58
Pages: 159-165
Description
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[Journal Article] Geomagnetic conjugate observation of nighttime medium-scale and large-scale traveling ionospheric disturbances: FRONT3 campaign2005
Author(s)
Shiokawa, K., Y. Otsuka, T. Tsugawa, T. Ogawa, A. Saito, K. 0hshima, M. Kubota, T. Maruyama, T. Nakamura, M. Yamamoto, P. Wilkinson
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Journal Title
J. Geophys. Res. 110, A05303
Pages: doi : 10.1029/2004JA010845
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Observations of equatorial plasma bubbles using broadcast VHF radio waves2005
Author(s)
Nakata, H., I. Nagashima, K. Sakata, Y. Otsuka, Y. Akaike, T. Takano, S. Shimakura, K. Shiokawa, T. Ogawa
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Journal Title
Geophys. Res. Lett. Vol. 32, No. 17
Pages: L17110, 10.1029/2005GL023243
Description
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[Presentation] Ionospheric total electron content variations after the Sumatra earthquake of December 26, 20042005
Author(s)
Otsuka, Y., N. Kotake, T. Tsugawa, K. Shiokawa, T. Ogawa, Effendy, T. Saito, M. Kawamura, T. Maruyama, N. Hemmakorn, T. Komolmis
Organizer
JPGU General Assembly 2005
Year and Date
20050522-20050526
Description
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