研究者詳細 - 大塚　雄一

論文 - 大塚　雄一

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Optical and radio measurements of a 630-nm airglow enhancement over Japan on 9 September 1999 査読有り

Otsuka, Y; Kadota, T; Shiokawa, K; Ogawa, T; Kawamura, S; Fukao, S; Zhang, SR

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 108 巻 ( A6 ) 2003年6月

Ground and satellite observations of nighttime medium-scale traveling ionospheric disturbance at midlatitude 査読有り

Shiokawa, K; Otsuka, Y; Ihara, C; Ogawa, T; Rich, FJ

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 108 巻 ( A4 ) 2003年4月

Damping of large-scale traveling ionospheric disturbances detected with GPS networks during the geomagnetic storm 査読有り

Tsugawa, T; Saito, A; Otsuka, Y; Yamamoto, M

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 108 巻 ( A3 ) 2003年3月

Statistical study of nighttime medium-scale traveling ionospheric disturbances using midlatitude airglow images 査読有り

Shiokawa, K; Ihara, C; Otsuka, Y; Ogawa, T

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 108 巻 ( A1 ) 2003年1月

Optical and radio measurements of a 630-nm enhancement over Japan on September 9, 1999 査読有り

Otsuka, Y., T. Kadota, K. Shiokawa, T. Ogawa, S. Kawamura,, S. Fukao, and S. -R. Zhang

J. Geophys. Res. 108(A6) 巻 ( 1252 ) 頁： doi:10.1029/2002JA009594 2003年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Using a comprehensive data set from optical and radio instruments, we investigate a midnight brightness wave that appeared in 630-nm airglow images over Japan on the night of September 9, 1999. This may be the first such observation of the brightness wave with an all-sky imager in the East-Asian longitudinal sector. The imager at Shigaraki (35.6N, 136.1E) tracked a north-northeastward propagation of the wave with an apparent velocity of 500 m/s after midnight. Ionosonde observations at five stations in Japan showed that rapid descent of the F2 layer propagated northward beyond 35N with decreasing amplitude. Incoherent scatter observations with the MU radar at Shigaraki also revealed that the F2 peak altitude decreased from 360 km to 280 km during the event. During the F2 layer descent, the altitude profile of the electron density became sharp, enhancing the F2 peak electron density. After the F2 layer altitude reached 280 km, electron density in the F2 layer rapidly decreased because of increased neutral density at low altitude. A Fabry-Perot interferometer (FPI) at Shigaraki observed northward neutral winds of 10--70 m/s during the event. A model calculation demonstrates that the meridional winds estimated from the MU radar electron density profiles are fairly well consistent with those observed with the FPI. From these results, we conclude that the observed northward wind enhancements, probably caused by the the midnight temperature maximum, pushed down the plasma in the F2 layer to lower altitudes along the geomagnetic field to cause the
630-nm airglow intensity enhancement.

A two-channel Fabry-Perot interferometer with thermoelectric-cooled CCD detectors for neutral wind measurement in the upper atmosphere 査読有り

Shiokawa, K; Kadota, T; Otsuka, Y; Ogawa, T; Nakamura, T; Fukao, S

EARTH PLANETS AND SPACE 55 巻 ( 5 ) 頁： 271 - 275 2003年

Simultaneous middle and upper atmosphere radar and ionospheric sounder observations of midlatitude E region irregularities and sporadic E layer 査読有り

Ogawa T, Takahashi O, Otsuka Y, Nozaki K, Yamamoto M, Kita K

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 107 巻 ( A10 ) 2002年10月

Annual and semiannual variations of the midlatitude ionosphere under low solar activity 査読有り

Kawamura, S; Balan, N; Otsuka, Y; Fukao, S

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 107 巻 ( A8 ) 2002年8月

Geomagnetic conjugate observations of equatorial airglow depletions 査読有り

Otsuka, Y; Shiokawa, K; Ogawa, T; Wilkinson, P

GEOPHYSICAL RESEARCH LETTERS 29 巻 ( 15 ) 2002年8月

A large-scale traveling ionospheric disturbance during the magnetic storm of 15 September 1999 査読有り

Shiokawa, K; Otsuka, Y; Ogawa, T; Balan, N; Igarashi, K; Ridley, AJ; Knipp, DJ; Saito, A; Yumoto, K

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 107 巻 ( A6 ) 2002年6月

*A new technique for mapping of total electron content using GPS network in Japan 査読有り

Otsuka, Y., T. Ogawa, A. Saito, T. Tsugawa, S. Fukao, and S. Miyazaki

Earth, Planets, and Space 54 巻頁： 63-70 2002年

Geomagnetic conjugate observations of equatorial airglow depletions 査読有り

Otsuka, Y., K. Shiokawa, T. Ogawa, and P. Wilkinson

Geophys. Res. Lett. 29 巻頁： 10.1029/2002GL015347 2002年

A new technique for mapping of total electron content using GPS network in Japan 査読有り

Otsuka, Y; Ogawa, T; Saito, A; Tsugawa, T; Fukao, S; Miyazaki, S

EARTH PLANETS AND SPACE 54 巻 ( 1 ) 頁： 63 - 70 2002年

Imaging observations of the equatorward limit of midlatitude traveling ionospheric disturbances 査読有り

Shiokawa, K; Otsuka, Y; Ejiri, MK; Sahai, Y; Kadota, T; Ihara, C; Ogawa, T; Igarashi, K; Miyazaki, S; Saito, A

EARTH PLANETS AND SPACE 54 巻 ( 1 ) 頁： 57 - 62 2002年

Observations and modeling of 630 nm airglow and total electron content associated with traveling ionospheric disturbances over Shigaraki, Japan 査読有り

Ogawa, T; Balan, N; Otsuka, Y; Shiokawa, K; Ihara, C; Shimomai, T; Saito, A

EARTH PLANETS AND SPACE 54 巻 ( 1 ) 頁： 45 - 56 2002年

Regional ionosphere map over Japanese Islands 査読有り

Ping, J; Kono, Y; Matsumoto, K; Otsuka, Y; Saito, A; Shum, C; Heki, K; Kawano, N

EARTH PLANETS AND SPACE 54 巻 ( 12 ) 頁： E13 - E16 2002年

Plasmaspheric electron content in the GPS ray paths over Japan under magnetically quiet conditions at high solar activity 査読有り

Balan, N; Otsuka, Y; Tsugawa, T; Miyazaki, S; Ogawa, T; Shiokawa, K

EARTH PLANETS AND SPACE 54 巻 ( 1 ) 頁： 71 - 79 2002年

Observations of traveling ionospheric disturbances and 3-m scale irregularities in the nighttime F-region ionosphere with the MU radar and a GPS network 査読有り

Saito A, Nishimura M, Yamamoto M, Fukao S, Tsugawa T, Otsuka Y, Miyazaki S, Kelley MC

EARTH PLANETS AND SPACE 54 巻 ( 1 ) 頁： 31 - 44 2002年

Annual and semiannual variations of the midlatitude ionosphere under low solar activity 査読有り

S. Kawamura, N. Balan, Y. Otsuka, S. Fukao

Journal of Geophysical Research: Space Physics 107 巻 ( 8 ) 2002年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Blackwell Publishing Ltd

The annual and semiannual variations of the midlatitude ionosphere under low solar activity are studied using middle and upper (MU) radar (135°E, 35°N) incoherent scatter observations and Sheffield University plasmasphere-ionosphere model (SUPIM). The variations of the daytime electron density (Ne) and electron and ion temperatures (Te and Ti) at 200-600 km altitudes measured by the radar under low solar activity (F10.7 ≤ 120) are satisfactorily reproduced for the first time by incorporating the radar measured values of the magnetic meridional neutral wind velocity (U 0) and northward perpendicular plasma drift velocity (V ⊥) into SUPIM that uses mass spectrometer incoherent scatter 1986 (MSIS-86) for neutral densities and neutral temperatures. The study shows that the annual and semiannual variations of the midlatitude ionosphere during daytime at altitudes near and above the ionospheric peak under low solar activity depend more on the direct effect of the neutral wind arising through the changes in ionospheric height than on the indirect effect arising through the changes in thermospheric composition (or atomic to molecular concentration ratio)
the indirect effect, however, predominates on the variations at altitudes below the ionospheric peak. The electron temperature (Te) undergoes similar but almost opposite seasonal and semiannual variations as the electron density. The ion temperature (Ti) is closer to neutral temperature than to electron temperature at altitudes up to ∼400 km and shows comparatively weak annual and semiannual variations. Copyright 2002 by the American Geophysical Union.

DOI： 10.1029/2001JA000267

Scopus

Imaging observations of midlatitude ionospheric disturbances during the geomagnetic storm of February 12, 2000 査読有り

Y Sahai, K Shiokawa, Y Otsuka, C Ihara, T Ogawa, K Igarashi, S Miyazaki, A Saito

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 106 巻 ( A11 ) 頁： 24481 - 24492 2001年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER GEOPHYSICAL UNION

Regular all-sky imaging observations of the F region OI 630 nm nightglow emission are carried out at Rikubetsu (43.5 degreesN) and Shigaraki (34.8 degreesN), Japan since 1998. In this paper, we present observations of the OI 630 nm emission images from these two sites with a cluster of other observations during the geomagnetic storm of February 12, 2000. The airglow observations were obtained between 1500 UT and 2000 UT (0000-0500 LT) on this night. Images from both Rikubetsu and Shigaraki show the presence of mesoscale-enhanced airglow bands moving slowly (similar to 20-30 m s(-1)) to the southwest direction. The mesoscale band structures were also detected by an extensive network of GPS signal observations over Japan. The airglow observations at Shigaraki also show intense OI 630 nm emission in the south with several small-scale intensity depletion structures. We suggest that these small-scale intensity depletion structures (scale size 30-50 km) are caused by possible nonlinear interaction between the mesoscale TIDs and enhanced regions of the equatorial ionospheric anomaly. The ionosonde observations from Wakkanai (45.4 degreesN) and Kokubunji (35.7 degreesN) show spread F signatures between 1130 and 2100 UT and 1215 and 1715 UT, respectively, whereas no spread F was observed at Yamagawa (31.2 degreesN) and Okinawa (26.3 degreesN). The phase fluctuations of GPS signal were observed at latitudes higher than 30 degreesN for 1400-1900 UT. These observations suggest enhanced storm time ionospheric disturbances were confined in the midlatitudes.

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