研究者詳細 - 塩川　和夫

論文 - 塩川　和夫

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A concentric gravity wave structure in the mesospheric airglow images 査読有り

Suzuki, S, Shiokawa, K, Otsuka, Y, Ogawa, T, Nakamura, K, Nakamura, T

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 112 巻 ( D2 ) 2007年1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：Journal of Geophysical Research Atmospheres

A concentric gravity wave pattern was observed by an all-sky airglow imager located at Shigaraki, Japan (34.9°N, 136.1°E) on 3 October 2002. The wave pattern was identified over 2.5 hours (1330-1600 UT or 2230-0100 LT) both in the OI (557.7 nm) and OH (720-910 nm) band images. It had a wavelength of about 35 km and propagated concentrically northeastward with a horizontal phase velocity of about 80 m/s. The wave had a short period of about 7 min and a momentum flux of 2.2 m2/s2. We identified the source of the waves as a cumulonimbus in the satellite cloud images and in radar precipitation images near the center of the concentric pattem. We conclude that this rare wave pattern was caused by a weak wind system that extended from the stratosphere to the mesopause region in an autumn transition. Copyright 2007 by the American Geophysical Union.

DOI： 10.1029/2005JD006558

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Gravity wave momentum flux in the upper mesosphere derived from OH airglow imaging measurements 査読有り

Suzuki Shin, Shiokawa Kazuo, Otsuka Yuichi, Ogawa Tadahiko, Kubota Minoru, Tsutsumi Masaki, Nakamura Takuji, Fritts David C.

EARTH PLANETS AND SPACE 59 巻 ( 5 ) 頁： 421 - 428 2007年

Simultaneous DMSP, all-sky camera, and IMAGE FUV observations of the brightening are at a substorm pseudo-breakup 査読有り

Yago K., Shiokawa K., Yumoto K., Baishev D. G., Solovyev S. I., Rich F. J.

EARTH PLANETS AND SPACE 59 巻 ( 1 ) 頁： 45 - 49 2007年

Development of airglow temperature photometers with cooled-CCD detectors 査読有り

Shiokawa K., Otsuka Y., Suzuki S., Katoh T., Katohl Y., Satoh M., Ogawa T., Takahashi H., Gobbli D., Nakamura T., Williams B. P., She C.-Y., Taguchi M., Shimomai T.

EARTH PLANETS AND SPACE 59 巻 ( 6 ) 頁： 585 - 599 2007年

The ionospheric response in the Brazilian sector during the super geomagnetic storm on 20 November 2003 査読有り

Becker-Guedes F., Sahai Y., Fagundes P. R., Espinoza E. S., Pillat V. G., Lima W. L. C., Basu Su., Basu Sa., Otsuka Y., Shiokawa K., MacKenzie E. M., Pi X., Bittencourt J. A.

ANNALES GEOPHYSICAE 25 巻 ( 4 ) 頁： 863 - 873 2007年

Summer-winter hemispheric asymmetry of sudden increase in ionospheric total electron content induced by solar flares:: A role of O/N2 ratio 査読有り

Tsugawa T., Sadakane T., Sato J., Otsuka Y., Ogawa T., Shiokawa K., Saito A.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 111 巻 ( A11 ) 2006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：Journal of Geophysical Research: Space Physics

Latitudinal and local time dependences of the sudden increase in total electron content (SITEC) of the ionosphere induced by solar flares were statistically studied. We analyzed 91 SITEC events associated with solar flares larger than M5 X-ray class from January 2000 to May 2005. Global total electron content (TEC) data from the Scripps Orbit and Permanent Array Center (SOPAC) GPS networks and X-ray flux data obtained by the Geosynchronous Operational Environmental Satellites (GOES) were used in this study. The global TEC maps revealed that the SITEC value basically depends on the cosine of solar zenith angle (SZA). However, we found that there were significant residuals δ from the linear fitting to the SZA for almost all the flare events. The value of δ is statistically larger in the winter hemisphere than in the summer hemisphere. The latitudinal difference of δ is ∼0.5 TECU between 50°N and 50°S in the solstice. On the other hand, there was not a clear statistical difference in δ between the morning and evening sectors. The similar summer-winter hemispheric asymmetry was also seen in the daytime distribution of the F region O/N2 density ratio in the MSISE-90 model. This result indicates that the SITEC phenomena induced by solar flares depend not only on the SZA but also on the O/N2 density ratio. The daytime F region electron density and the background TEC is well known to be determined basically by the O/N2 ratio. It is reasonable that the O/N2 ratio affects the sudden increase in TEC in the same sense as it determines the background TEC. Copyright 2006 by the American Geophysical Union.

DOI： 10.1029/2006JA011951

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A fast-propagating, large-scale atmospheric gravity wave observed in the WAVE2004 campaign 査読有り

Kubota, M; Kawamura, S; Abo, M; Koizumi, Y; Murayama, Y; Yamamori, M; Shiokawa, K; Otsuka, Y; Uchiumi, M; Igarashi, K; Abe, T; Oyama, KI; Iwagami, N

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 111 巻 ( D21 ) 頁： D21110 - D21110 2006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：Journal of Geophysical Research Atmospheres

The Waves in Airglow Campaign in 2004 (WAVE2004), which aimed to elucidate the formation process of waves in airglow structures from both dynamical and chemical perspectives, was conducted using rocket-borne and ground-based instruments in Japan on 17 January 2004. In this experiment, we observed a large-scale atmospheric gravity wave (AGW), which appeared in both the vertical profiles of sodium density obtained by a Na lidar and the horizontal distributions of airglow emission obtained by an all-sky imager (ASI). Vertical propagation of the AGW accompanied by a shortening of its vertical wavelength was clearly visualized using the Na lidar data. The horizontal wavelength, horizontal phase velocity, period, and propagation direction of the AGW were estimated from the ASI data as 673-774 km, 107-122 m/s, ∼1.75 hours, and north-northeastward, respectively. Using these parameters and the MF radar wind, vertical wavelengths of the wave were calculated from the dispersion relation of gravity waves. The calculated vertical wavelengths were comparable at altitudes of 85.5 km and 93.25 km to those estimated from the variation of the sodium density. Using a simple ray tracing technique, the AGW was traced back to the southern edge of the distorted jet stream near tropopause. This result strongly suggests that an unstable baroclinic wave associated with ageostrophic motions in the jet stream was the wave source of the large-scale AGW observed in the WAVE2004. Copyright 2006 by the American Geophysical Union.

DOI： 10.1029/2005JD006788

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B153 地上からの光学・電波による中間圏重力波の観測(スペシャルセッション「高解像度気候モデルによる中層大気研究の可能性」) 査読有り

中村卓司, 塩川和夫, 堤雅基, 川原琢哉

大会講演予講集 90 巻頁： 100 2006年9月

Estimating drift velocity of polar cap patches with all-sky airglow imager at Resolute Bay, Canada 査読有り

Hosokawa K., Shiokawa K., Otsuka Y., Nakajima A., Ogawa T., Kelly J. D.

GEOPHYSICAL RESEARCH LETTERS 33 巻 ( 15 ) 2006年8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：Geophysical Research Letters

Highly sensitive all-sky airglow imager has been operative at Resolute Bay, Canada (74.73°N, 265.07°E; AACGM latitude 82.9°) since January 2005. We present, as a first result from the imager, an event of polar cap patches drifting anti-sunward during the southward IMF conditions. Magnitude and direction of patch drift velocities are computed with a temporal resolution of 2 min by using the newly developed patch-tracking algorithm based on 2D cross correlation analysis. It is well visualized that the patches change their moving speed and direction drastically in a short time scale (a few minutes). Speed of the patch is primally controlled by the IMF Bz. Dawn-dusk component of the patch drift velocities is well correlated with the IMF By in agreement with published By dependence of the nightside polar cap convection. However, response of the patch drift direction to the IMF By is found to be much slower (≈20 min) than that of the drift speed to the IMF Bz almost instantaneous. Copyright 2006 by the American Geophysical Union.

DOI： 10.1029/2006GL026916

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Ionospheric disturbances over Indonesia and their possible association with atmospheric gravity waves from the troposphere 査読有り

Ogawa Tadahiko, Otsuka Yuichi, Shiokawa Kazuo, Saito Akinori, Nishioka Michi

JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 84A 巻頁： 327 - 342 2006年7月

Equatorial ionospheric scintillations and zonal irregularity drifts observed with closely-spaced GPS receivers in Indonesia 査読有り

Otsuka Yuichi, Shiokawa Kazuo, Ogawa Tadahiko

JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 84A 巻頁： 343 - 351 2006年7月

A multi-instrument measurement of a mesospheric front-like structure at the equator 査読有り

Shiokawa Kazuo, Suzuki Shin, Otsuka Yuichi, Ogawa Tadahiko, Nakamura Takuji, Mlynczak Martin G., Russell James M. III

JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN 84A 巻頁： 305 - 316 2006年7月

Quasiperiodic southward moving waves in 630-nm airglow images in the equatorial thermosphere 査読有り Open Access

Shiokawa, K; Otsuka, Y; Ogawa, T

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 111 巻 ( A6 ) 2006年6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：Journal of Geophysical Research: Space Physics

We report quasiperiodic southward moving waves, which are commonly observed in the 01 630-nm airglow images (emission altitudes of 200-300 km) near the equator, in 2-year airglow observations at Kototabang, Indonesia (0.2°S, 100.3°E, geomagnetic latitude of -10.4°). The waves have predominantly east-west phase fronts and repeatedly propagate southward with a velocity of 310 ± 110 m/s and a period of 40 ± 15 min. They are frequently observed in May-July with an occurrence rate of 53% and are also observed in other seasons with occurrences of ∼20%. The waves are observed in and to the south (geomagnetically poleward) of the equatorial ionospheric anomaly, which is identified as an airglow enhancement region moving gradually to lower geomagnetic latitudes at the premidnight local times. We suggest that gravity waves in the lower thermosphere below ∼300 km are a plausible cause of the observed quasiperiodic waves in the airglow images. Copyright 2006 by the American Geophysical Union.

DOI： 10.1029/2005JA011406

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Geomagnetic conjugate observations of large-scale traveling ionospheric disturbances using GPS networks in Japan and Australia 査読有り

Tsugawa, T; Shiokawa, K; Otsuka, Y; Ogawa, T; Saito, A; Nishioka, M

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 111 巻 ( A2 ) 2006年2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：Journal of Geophysical Research: Space Physics

The geomagnetic conjugacy of large-scale traveling ionospheric disturbances (LSTIDs) was studied using total electron content (TEC) data derived from GPS networks in Japan and Australia. The number of simultaneous occurrences of LSTIDs within ±1 hour in both hemispheres was 5 out of 20 (21) events in Japan (Australia) when Kp ≥ 5- and 0 out of 15 (10) when Kp ≤ 4+. As for the LSTIDs observed simultaneously in both hemispheres, the propagation velocities of equatorward LSTID were comparable between the two hemispheres, with differences of 10-40%. The crossing times at 30° geomagnetic latitude of the simultaneous LSTIDs over Japan and Australia were also different by several tens of minutes for all five events. These observational results indicate that the LSTIDs observed almost simultaneously in both hemispheres are not connected electromagnetically through the geomagnetic field but are generated by atmospheric gravity waves propagating to the equator independently in the two hemispheres. Copyright 2006 by the American Geophysical Union.

DOI： 10.1029/2005JA011300

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ERG - A small-satellite mission to investigate the dynamics of the inner magnetosphere 査読有り

Shiokawa K., Seki K., Miyoshi Y., Ieda A., Ono T., Iizima M., Nagatsuma T., Obara T., Takashima T., Asamura K., Kasaba Y., Matsuoka A., Saito Y., Saito H., Hirahara M., Tonegawa Y., Toyama F., Tanaka M., Nose M., Kasahara Y., Yumoto K., Kawano H., Yoshikawa A., Ebihara Y., Yukimatsu A., Sato N., Watanabe S.

MAGNETOSPHERIC DYNAMICS AND THE INTERNATIONAL LIVING WITH A STAR PROGRAM 38 巻 ( 8 ) 頁： 1861-1869 2006年

Signatures of 3-6 day planetary waves in the equatorial mesosphere and ionosphere 査読有り

Takahashi H., Wrasse C. M., Pancheva D., Abdu M. A., Batista I. S., Lima L. M., Batista P. P., Clemesha B. R., Shiokawa K.

ANNALES GEOPHYSICAE 24 巻 ( 12 ) 頁： 3343 - 3350 2006年

GPS detection of total electron content variations over Indonesia and Thailand following the 26 December 2004 earthquake 査読有り

Otsuka Y, Kotake N, Tsugawa T, Shiokawa K, Ogawa T, Effendy, Saito S, Kawamura M, Maruyama T, Hemmakorn N, Komolmis T

EARTH PLANETS AND SPACE 58 巻 ( 2 ) 頁： 159 - 165 2006年

the Inner Magnetosphere Subgroup in the Society of Geomagnetism and Earth, Planetary and Space Sciences ERG -A small-satellite mission to investigate the dynamics of the inner magnetosphere 査読有り

塩川和夫

Adv. Space Res 38(8) 頁： 1861 - 1869 2006年

Effects of the major geomagnetic storms of October 2003 on the equatorial and low-latitude F region in two longitudinal sectors -: art. no. A12S91 査読有り

Sahai, Y; Fagundes, PR; Becker-Guedes, F; Bolzan, MJA; Abalde, JR; Pillat, VG; de Jesus, R; Lima, WLC; Crowley, G; Shiokawa, K; MacDougall, JW; Lan, HT; Igarashi, K; Bittencourt, JA

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 110 巻 ( A12 ) 2005年12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：Journal of Geophysical Research: Space Physics

The intense modifications in the ionosphere-thermosphere system in the equatorial and low-latitude regions associated with the dynamic and electrodynamic coupling from high to low latitudes and chemical changes during geomagnetic storms are important space weather issues. In the second half of October 2003, the intense solar activity resulted in one intense and two major geomagnetic storms on 29 and 30 October. In this paper we present and discuss the ionospheric sounding observations carried out from Palmas and São José dos Campos, Brazil (the Brazilian sector), and Ho Chi Minh City, Vietnam, and Okinawa, Japan (the East Asian sector), during these storms. The two sectors are separated by about 12 hours in local time (so while one sector is in daytime, the other one is in nighttime) and provide valuable information related to the storm-time longitudinal differences. Copious storm-time changes were observed in both sectors. It should be pointed out that the two longitudinal sectors investigated in the present study clearly show the global nature of the storm-time effects. However, the responses to the storm-time effects are also associated with the local time in the two sectors. The present investigations show that there are both similarities and differences in the storm-time response in the two sectors. During the storm main phases, with sharp decreases of the Dst index, both sectors showed (dusk or dawn periods) fast uplifting of the F layer associated with magnetospheric electric field penetration. Although in the East Asian sector, Ho Chi Minh City and Okinawa are located fairly close in longitude, with only 2 hour difference in local lime, on occasions the storm-time responses have been very different. Some differences in the latitudinal response of the F region were also observed in the two sectors. Both positive and negative storm phases have been observed at all the four stations. A comparison of the ionospheric parameters obtained from the TIMEGCM model runs and the observed ionospheric parameters at the four stations shows a reasonable agreement during the quiet periods. During the geomagnetic disturbance period, when there were sharp decreases in Dst, some of the observed rapid uplifts of the F region peak heights are not reproduced by the model results. Also, sometimes the model foF2 results differ considerably from the observed foF2 variations. The period investigated represents an extreme storm situation for validation of the model and points to ways in which the model might be improved in the future.

DOI： 10.1029/2004JA010999

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Ground and satellite observations of substorm onset arcs 査読有り Open Access

Shiokawa, K; Yago, K; Yumoto, K; Baishev, DG; Solovyev, SI; Rich, FJ; Mende, SB

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 110 巻 ( A12 ) 2005年12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：Journal of Geophysical Research: Space Physics

Auroral features and associated particles and fields are investigated for a sequence of substorm onsets observed at ∼1900 MLT on 24 October 2000. During a 30-min interval at 1020-1050 UT, we identified three Pi 2 wave packets with positive H enhancements at midlatitudes and associated auroral brightenings in auroral images obtained by a ground all-sky camera and the IMAGE FUV imager. The DMSP F15 satellite crossed brightening arcs during the third Pi 2 pulsation in the field-of-view of the ground camera at Tixie (66.0° MLAT), Russia. The crossing was 1-2 hours duskside of the main onset local time. The brightening arcs were located in the region 1 upward field-aligned current system. The most equatorward arc, which brightened just after the second Pi 2 pulsation, was at the equatorward boundary of the region 1 current and in the sunward convection region. The arcs corresponded to inverted-V accelerated electrons with energies of ∼10 keV. On the basis of these simultaneous ground-satellite measurements, we discuss substorm onset models of reconnection/flow braking and near-Earth plasma sheet instabilities. Copyright 2005 by the American Geophysical Union.

DOI： 10.1029/2005JA011281

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