研究者詳細 - 大塚　雄一

論文 - 大塚　雄一

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Spatial relationship of equatorial plasma bubbles and field-aligned irregularities observed with an all-sky airglow imager and the Equatorial Atmosphere Radar 査読有り

Otsuka, Y; Shiokawa, K; Ogawa, T; Yokoyama, T; Yamamoto, M; Fukao, S

GEOPHYSICAL RESEARCH LETTERS 31 巻 ( 20 ) 2004年10月

Statistical characteristics of gravity waves observed by an all-sky imager at Darwin, Australia - art. no. D20S07 査読有り Open Access

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

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 109 巻 ( D20 ) 頁： D20 - S07 2004年8月

Geomagnetic conjugate observations of medium-scale traveling ionospheric disturbances at midlatitude using all-sky airglow imagers - art. no. L15803 査読有り

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

GEOPHYSICAL RESEARCH LETTERS 31 巻 ( 15 ) 2004年8月

Comparison of OH rotational temperatures measured by the spectral airglow temperature imager (SATI) and by a tilting-filter photometer 査読有り

Shiokawa, K; Otsuka, Y; Ogawa, T; Takahashi, H; Nakamura, T; Shimomai, T

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS 66 巻 ( 11 ) 頁： 891 - 897 2004年7月

A statistical study of large-scale traveling ionospheric disturbances using the GPS network in Japan - art. no. A06302 査読有り Open Access

Tsugawa, T; Saito, A; Otsuka, Y

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 109 巻 ( A6 ) 頁： A06302 2004年6月

Simultaneous mesosphere/lower thermosphere and thermospheric F region observations during geomagnetic storms 査読有り

Balan N, Kawamura S, Nakamura T, Yamamoto M, Fukao S, Igarashi K, Maruyama T, Shiokawa K, Otsuka Y, Ogawa T, Alleyne H, Watanabe S, Murayama Y

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 109 巻 ( A4 ) 2004年4月

*Geomagnetic conjugate observations of medium-scale traveling ionospheric disturbances at midlatitude using all-sky airglow imagers 査読有り

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

Geophys. Res. Lett. 31 巻 ( L15803 ) 頁： doi:10.1029/2004GL020262 2004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）

We report for the first time simultaneous observations of medium-scale traveling ionospheric disturbances (MSTIDs) at geomagnetic conjugate points in both hemispheres, using two all-sky airglow imagers at midlatitudes. A 630-nm all-sky CCD imager at Sata, Japan, detected MSTIDs with a wavefront elongated from NW to SE on the night of August 9, 2002. During this event, MSTIDs with a wavefront elongated from SW to NE were observed at the geomagnetic conjugate point, Darwin, Australia. The MSTID structures mapped from Darwin to its magnetic conjugate points along the geomagnetic field lines B coincide closely with those in the Sata images. This result suggests that polarization electric field (Ep) plays an important role in the generation of MSTIDs. Ep maps along B and moves the F region plasma upward or downward by ExB drifts, causing plasma density perturbations with structures mirrored in the northern and southern hemispheres.

Spatial relationship of equatorial plasma bubbles and field-aligned irregularities observed with an all-sky airglow imager and the Equatorial Atmosphere Radar 査読有り

Otsuka, Y., K. Shiokawa, T. Ogawa, T. Yokoyama, M. Yamamoto, and S. Fukao

Geophys. Res. Lett. 31 巻 ( L20802 ) 頁： 10.1029/2004GL020869 2004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）

We report, for the first time, simultaneous two-dimensional observations of 630-nm airglow depletions and radar backscatter from field-aligned irregularities (FAI) associated with equatorial plasma bubbles. Spatial distributions of backscatter were obtained by performing
east-west scans with the 47-MHz Equatorial Atmosphere Radar (EAR) in West Sumatra, Indonesia. A 630-nm airglow depletion, caused by a plasma bubble, was simultaneously
observed with an all-sky airglow imager.
Both the airglow depletion and backscatter region appeared as band-like structure elongated in the meridional direction with a zonal width of about 100 km. To compare the spatial structures of backscatter with that of airglow depletion,
the backscatter was projected onto a horizontal plane at 250-km altitude. Backscatter was found to occur within the entire airglow-depleted region.

DOI： 10.1029/2004GL020869

Generation of large-scale equatorial F-region plasma depletions during low range spread-F season 査読有り Open Access

Sahai, Y; Fagundes, PR; Abalde, JR; Pimenta, AA; Bittencourt, JA; Otsuka, Y; Rios, VH

ANNALES GEOPHYSICAE 22 巻 ( 1 ) 頁： 15 - 23 2004年

Time evolution of high-altitude plasma bubbles imaged at geomagnetic conjugate points 査読有り Open Access

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

ANNALES GEOPHYSICAE 22 巻 ( 9 ) 頁： 3137 - 3143 2004年

Ray-tracing Calculation of VHF Radio Waves Scattered by Field-aligned Irregularities Associated with Equatorial Plasma Bubbles 査読有り

Hiroyuki Nakata, Yoshiaki Akaike, Yuichi Otsuka, Toshiaki Takano, Satoshi Ujigawa, Ikuo Nagashima

IEEJ Transactions on Fundamentals and Materials 124 巻 ( 12 ) 頁： 1253 - 1254 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

In order to explain the propagation of VHF radio waves for TV broadcasting transmitted from Southeast Asia associated with equatorial plasma bubbles, we have examined ray paths of the radio waves scattered by field-aligned irregularities in equatorial plasma bubbles. In determining the ray paths of the radio waves, a ray tracing calculation combined with a model of the scattering by field-aligned irregularities is used. It is found that VHF radio waves transmitted from Philippines can propagate to Japan due to scattering by field-aligned irregularities located above the East China Sea. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.124.1253

Scopus

Thermospheric wind during a storm-time large-scale traveling ionospheric disturbance - art. no. 1423 査読有り Open Access

Shiokawa, K; Otsuka, Y; Ogawa, T; Kawamura, S; Yamamoto, M; Fukao, S; Nakamura, T; Tsuda, T; Balan, N; Igarashi, K; Lu, G; Saito, A; Yumoto, K

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 108 巻 ( A12 ) 2003年12月

Optical and radio measurements of a 630-nm airglow enhancement over Japan on 9 September 1999 - art. no. 1252 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 - art. no. 1145 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 - art. no. 1127 査読有り Open Access

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 - art. no. 1052 査読有り Open Access

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 Open Access

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 - art. no. 1166 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

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