研究者詳細 - 塩川　和夫

論文 - 塩川　和夫

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Geomagnetically conjugate observation of plasma bubbles and thermospheric neutral winds at low latitudes 査読有り

Fukushima D., Shiokawa K., Otsuka Y., Nishioka M., Kubota M., Tsugawa T., Nagatsuma T., Komonjinda S., Yatini C. Y.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 120 巻 ( 3 ) 頁： 2222 - 2231 2015年3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

This is the first paper that reports simultaneous observations of zonal drift of plasma bubbles and the thermospheric neutral winds at geomagnetically conjugate points in both hemispheres. The plasma bubbles were observed in the 630 nm nighttime airglow images taken by using highly sensitive all-sky airglow imagers at Kototabang, Indonesia (geomagnetic latitude (MLAT): 10.0S), and Chiang Mai, Thailand (MLAT: 8.9N), which are nearly geomagnetically conjugate stations, for 7 h from 13 to 20 UT (from 20 to 03 LT) on 5 April 2011. The bubbles continuously propagated eastward with velocities of 100-125 m/s. The 630 nm images at Chiang Mai and those mapped to the conjugate point of Kototabang fit very well, which indicates that the observed plasma bubbles were geomagnetically connected. The eastward thermospheric neutral winds measured by two Fabry-Perot interferometers were 70-130 m/s at Kototabang and 50-90 m/s at Chiang Mai. We compared the observed plasma bubble drift velocity with the velocity calculated from the observed neutral winds and the model conductivity, to investigate the F region dynamo contribution to the bubble drift velocity. The estimated drift velocities were 60-90% of the observed velocities of the plasma bubbles, suggesting that most of the plasma bubble velocity can be explained by the F region dynamo effect.

DOI： 10.1002/2014JA020398

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CDF data archive and integrated data analysis platform for ERG-related ground data developed by ERG Science Center (ERG-SC) 査読有り

Hori, T, Y. Miyashita, Y. Miyoshi, K. Seki, T. Segawa, Y.-M. Tanaka, K. Keika, M. Shoji, I. Shinohara, K. Shiokawa, Y. Otsuka, S. Abe, A. Yoshikawa, K. Yumoto, Y. Obana, N. Nishitani, A. S. Yukimatu, T. Nagatsuma, M. Kunitake, K. Hosokawa, Y. Ogawa, K. T. Murata, M. Nose, H. Kawano, T. Sakanoi

宇宙航空研究開発機構研究開発報告: 宇宙科学情報解析論文誌 4 (JAXA-RR-14-009) 巻頁： 75 - 89 2015年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

The Exploration of energization and Radiation in Geospace project Science Center (ERG-SC) has developed the science data file archive and integrated data analysis tool for the ground network observation data of the ERG project. We have organized data design consortiums to develop and elaborate the standard metadata and data variable sets for each type of the ERG-related ground data being archived as Common Data Format (CDF) files. The integrated data analysis software for the project has also been developed on the basis of the Space Physics Environment Data Analysis Software (SPEDAS) which works in concert with the CDF data file repository. The software tools, which are provided as plug-in libraries for SPEDAS, are made available to the international science community so that scientists and students are ready to proceed to integrated studies combining the ground data with other satellite and simulation data seamlessly. The integrated data analysis software can make scientific activities more productive and help the ERG project achieve the scientific goals.

Polarization analysis of VLF/ELF waves observed at subauroral latitudes during the VLF-CHAIN campaign 査読有り

Martinez-Calderon Claudia, Shiokawa Kazuo, Miyoshi Yoshizumi, Ozaki Mitsunori, Schofield Ian, Connors Martin

EARTH PLANETS AND SPACE 67 巻 2015年2月

The geospace response to variable inputs from the lower atmosphere: a review of the progress made by Task Group 4 of CAWSES-II 査読有り

Oberheide Jens, Shiokawa Kazuo, Gurubaran Subramanian, Ward William E., Fujiwara Hitoshi, Kosch Michael J., Makela Jonathan J., Takahashi Hisao

PROGRESS IN EARTH AND PLANETARY SCIENCE 2 巻 2015年2月

Daytime tweek atmospherics 査読有り

Ohya Hiroyo, Shiokawa Kazuo, Miyoshi Yoshizumi

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 120 巻 ( 1 ) 頁： 654-665 2015年1月

A statistical study of satellite traces and evolution of equatorial spread F 査読有り

Narayanan Viswanathan Lakshmi, Sau Sukanta, Gurubaran Subramanian, Shiokawa Kazuo, Balan Nanan, Emperumal Kaliappan, Sripathi Samireddipalle

EARTH PLANETS AND SPACE 66 巻 2014年12月

CME front and severe space weather 査読有り

Balan N., Skoug R., Ram S. Tulasi, Rajesh P. K., Shiokawa K., Otsuka Y., Batista I. S., Ebihara Y., Nakamura T.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 12 ) 頁： 10,041 - 10,058 2014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

Thanks to the work of a number of scientists who made it known that severe space weather can cause extensive social and economic disruptions in the modern high-technology society. It is therefore important to understand what determines the severity of space weather and whether it can be predicted. We present results obtained from the analysis of coronal mass ejections (CMEs), solar energetic particle (SEP) events, interplanetary magnetic field (IMF), CME-magnetosphere coupling, and geomagnetic storms associated with the major space weather events since 1998 by combining data from the ACE and GOES satellites with geomagnetic parameters and the Carrington event of 1859, the Quebec event of 1989, and an event in 1958. The results seem to indicate that (1) it is the impulsive energy mainly due to the impulsive velocity and orientation of IMF Bz at the leading edge of the CMEs (or CME front) that determine the severity of space weather. (2) CMEs having high impulsive velocity (sudden nonfluctuating increase by over 275 km s-1 over the background) caused severe space weather (SvSW) in the heliosphere (failure of the solar wind ion mode of Solar Wind Electron Proton Alpha Monitor in ACE) probably by suddenly accelerating the high-energy particles in the SEPs ahead directly or through the shocks. (3) The impact of such CMEs which also show the IMF Bz southward from the leading edge caused SvSW at the Earth including extreme geomagnetic storms of mean DstMP <-250 nT during main phases, and the known electric power outages happened during some of these SvSW events. (4) The higher the impulsive velocity, the more severe the space weather, like faster weather fronts and tsunami fronts causing more severe damage through impulsive action. (5) The CMEs having IMF Bz northward at the leading edge do not seem to cause SvSW on Earth, although, later when the IMF Bz turns southward, they can lead to super geomagnetic storms of intensity (Dstmin) less than even -400 nT. Key Points Impulsive energy at CME front causes severe space weather (SvSW) in heliosphere Impulsive energy and IMF Bz southward at the CME front causes SvSW at the Earth Northward IMF Bz at the CME front causes normal space weather at the Earth

DOI： 10.1002/2014JA020151

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Airglow observations of nighttime medium-scale traveling ionospheric disturbances from Yonaguni: Statistical characteristics and low-latitude limit 査読有り

Narayanan V. Lakshmi, Shiokawa K., Otsuka Y., Saito S.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 11 ) 頁： 9268 - 9282 2014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

The characteristics of nighttime medium-scale traveling ionospheric disturbance (MSTID) features observed over Yonaguni (24.5°N, 123.0°E; 19.3°N dip latitude), Japan are studied using all-sky imaging of OI 630.0 nm airglow emission. The uniqueness of these observations is that the area observed by the imager covers the transition region between low to middle latitudes in the ionosphere. Typical low-latitude limit of midlatitude-type nighttime MSTIDs possessing phase front alignments along the northwest to the southeast occurs in this region. These MSTID features are rarely sighted at dip latitudes below 15°. We selected 2 year period for analysis in which 1 year corresponded to the solar minimum conditions and another year to the solar maximum conditions. The MSTIDs were observed to extend to farther lower latitudes during the solar minimum conditions than during the solar maximum periods. Their observed range of wavelengths, phase velocities, phase front alignment, and propagation directions are similar to those observed at typical midlatitude sites. However, on many occasions the phase fronts of the observed MSTIDs did not extend over the whole field of view of the imager indicating that some process inhibits their extension to further lower latitudes. Detailed investigation suggests that the poleward propagating enhancement of airglow intensity, probably associated with the midnight pressure bulge, causes the MSTID features to disappear when they reach lower latitudes later in the night. When the MSTIDs reach lower latitudes well before midnight, they are found to be inhibited by the equatorial ionization anomaly crest region.

DOI： 10.1002/2014JA020368

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Traveling planetary wave activity from mesopause region airglow temperatures determined by the Network for the Detection of Mesospheric Change (NDMC) 査読有り

Reisin E. R., Scheer J., Dyrland M. E., Sigernes F., Deehr C. S., Schmidt C., Hoeppner K., Bittner M., Ammosov P. P., Gavrilyeva G. A., Stegman J., Perminov V. I., Semenov A. I., Knieling P., Koppmann R., Shiokawa K., Lowe R. P., Lopez-Gonzalez M. J., Rodriguez E., Zhao Y., Taylor M. J., Buriti R. A., Espy P. J., French W. J. R., Eichmann K. -U., Burrows J. P., von Savigny C.

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS 119 巻頁： 71 - 82 2014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 Atmospheric and Solar-Terrestrial Physics

The global distribution of traveling planetary wave (PW) activity in the mesopause region is estimated for the first time from ground-based airglow measurements. Monthly and total mean climatologies of PW power are determined from rotational temperatures measured at 19 sites from 78° N to 76° S which contribute to the Network for the Detection of Mesospheric Change (NDMC). Wave power is expressed as the standard deviation of nocturnal mean temperature around the seasonal temperature variation. The results from 20° N confirm the SABER traveling PW proxy by Offermann et al. (2009, J. Geophys. Res. 114, D06110) at two altitudes. Most sites between 69° S and 69° N show total mean traveling PW activity of about 6. K, and only some high latitude sites have considerably higher activity levels. At the two tropical sites, there is practically no seasonal variation of PW activity. At 70% of the midlatitude sites, the seasonal variation is moderate for most of the year, but it is quite appreciable at all high latitude sites. Results about traveling PW activity at 87. km and 95. km available from several sites signal similar behavior at both altitudes. The total mean climatological results here obtained have further been used to separate the traveling PW contribution from the superposition of wave types contained in OH rotational temperature fluctuations measured by the SCIAMACHY instrument on Envisat. A narrow equatorial wave activity maximum is probably caused by gravity waves, while a tendency towards greater activity at higher northern latitudes may be due to stationary planetary waves. © 2014 Elsevier Ltd.

DOI： 10.1016/j.jastp.2014.07.002

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地球磁気圏におけるオーロラの物理 (小特集太陽系プラズマ) -- (地球磁気圏) 査読有り

塩川和夫

プラズマ・核融合学会誌 90 巻 ( 11 ) 頁： 708-712 2014年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

オーロラは,磁気圏でのプラズマ変動を,地球大気に投影した形で2次元的に可視化し,その面的な把握を可能にする.近年のオーロラカメラの高感度化や多点化,米国THEMIS衛星や日本のれいめい衛星により,オーロラを通して磁気圏のさまざまな変動の様子が明らかになってきた.本節ではその中で,オーロラサブストーム,パルセィティングオーロラや波動と粒子の相互作用,共回転オーロラやブラックオーロラなどに代表されるプラズマの微細空間構造に関して,近年の主だった研究成果を紹介する.

Study of Pc1 pearl structures observed at multi-point ground stations in Russia, Japan, and Canada 査読有り

Jun Chae-Woo, Shiokawa Kazuo, Connors Martin, Schofield Ian, Poddelsky Igor, Shevtsov Boris

EARTH PLANETS AND SPACE 66 巻 2014年10月

Auroral fragmentation into patches 査読有り

Shiokawa Kazuo, Hashimoto Ayumi, Hori Tomoaki, Sakaguchi Kaori, Ogawa Yasunobu, Donovan Eric, Spanswick Emma, Connors Martin, Otsuka Yuichi, Oyama Shin-Ichiro, Nozawa Satonori, McWilliams Kathryn

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 10 ) 頁： 8249-8261 2014年10月

3D imaging reveals electrodynamics of polar cap aurora 査読有り

Dahlgren Hanna, Perry Gareth, St Maurice Jean-Pierre, Sundberg Torbjorn, Hosokawa Keisuke, Semeter Joshua L., Nicolls Michael J., Shiokawa Kazuo

ASTRONOMY & GEOPHYSICS 55 巻 ( 5 ) 頁： . 2014年10月

P130 広域多地点大気光観測による中間圏大気重力波(ポスター・セッション) 査読有り

鈴木臣, 塩川和夫, 大塚雄一, 川村誠治, 村山泰啓

大会講演予講集 106 巻頁： 212 2014年9月

Ground-based ELF/VLF chorus observations at subauroral latitudes-VLF-CHAIN Campaign 査読有り

Shiokawa Kazuo, Yokoyama Yu, Ieda Akimasa, Miyoshi Yoshizumi, Nomura Reiko, Lee Sungeun, Sunagawa Naoki, Miyashita Yukinaga, Ozaki Mitsunori, Ishizaka Kazumasa, Yagitani Satoshi, Kataoka Ryuho, Tsuchiya Fuminori, Schofield Ian, Connors Martin

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 9 ) 2014年9月

New statistical analysis of the horizontal phase velocity distribution of gravity waves observed by airglow imaging 査読有り

Matsuda Takashi S., Nakamura Takuji, Ejiri Mitsumu K., Tsutsumi Masaki, Shiokawa Kazuo

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 119 巻 ( 16 ) 頁： 9707 - 9718 2014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：Journal of Geophysical Research: Atmospheres

We have developed a new analysis method for obtaining the power spectrum in the horizontal phase velocity domain from airglow intensity image data to study atmospheric gravity waves. This method can deal with extensive amounts of imaging data obtained on different years and at various observation sites without bias caused by different event extraction criteria for the person processing the data. The new method was applied to sodium airglow data obtained in 2011 at Syowa Station (69°S, 40°E), Antarctica. The results were compared with those obtained from a conventional event analysis in which the phase fronts were traced manually in order to estimate horizontal characteristics, such as wavelengths, phase velocities, and wave periods. The horizontal phase velocity of each wave event in the airglow images corresponded closely to a peak in the spectrum. The statistical results of spectral analysis showed an eastward offset of the horizontal phase velocity distribution. This could be interpreted as the existence of wave sources around the stratospheric eastward jet. Similar zonal anisotropy was also seen in the horizontal phase velocity distribution of the gravity waves by the event analysis. Both methods produce similar statistical results about directionality of atmospheric gravity waves. Galactic contamination of the spectrum was examined by calculating the apparent velocity of the stars and found to be limited for phase speeds lower than 30 m/s. In conclusion, our new method is suitable for deriving the horizontal phase velocity characteristics of atmospheric gravity waves from an extensive amount of imaging data.

DOI： 10.1002/2014JD021543

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Diagnostics of equatorial and low latitude ionosphere by TEC mapping over Brazil 査読有り

Takahashi H., Costa S., Otsuka Y., Shiokawa K., Monico J. F. G., Paula E., Nogueira P., Denardini C. M., Becker-Guedes F., Wrasse C. M., Ivo A. S., Gomes V. C. F., Gargarela W. Jr., Sant'Anna N., Gatto R.

ADVANCES IN SPACE RESEARCH 54 巻 ( 3 ) 頁： 385 - 394 2014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：Advances in Space Research

The total electron content (TEC) in the equatorial and low-latitude ionosphere over Brazil was monitored in two dimensions by using 2011 data from the ground-based global navigation satellite system (GNSS) receiver network operated by the Brazilian Institute for Geography and Statistics. It was possible to monitor the spatial and temporal variations in TEC over Brazil continuously during both day and night with a temporal interval of 10 min and a spatial resolution of about 400 km. The daytime equatorial ionization anomaly (EIA) and post-sunset plasma enhancement (PS-EIA) were monitored over an area corresponding to a longitudinal extension of 4000 km in South America. Considerable day-to-day variation was observed in EIA and PS-EIA. A large latitudinal and longitudinal gradient of TEC indicated a significant ionospheric range error in application of the GNSS positioning system. Large-scale plasma bubbles after sunset were also mapped over a wide range. Depletions with longitudinally separated by more than 800 km were observed. They were extended by more than 2000 km along the magnetic field lines and drifted eastward. It is expected that 2-dimensional TEC mapping can serve as a useful tool for diagnosing ionospheric weather, such as temporal and spatial variation in the equatorial plasma trough and crest, and particularly for monitoring the dynamics of plasma bubbles. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.asr.2014.01.032

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Day-night coupling by a localized flow channel visualized by polar cap patch propagation 査読有り

Nishimura Y., Lyons L. R., Zou Y., Oksavik K., Moen J. I., Clausen L. B., Donovan E. F., Angelopoulos V., Shiokawa K., Ruohoniemi J. M., Nishitani N., McWilliams K. A., Lester M.

GEOPHYSICAL RESEARCH LETTERS 41 巻 ( 11 ) 頁： 3701 - 3709 2014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：Geophysical Research Letters

We present unique coordinated observations of the dayside auroral oval, polar cap, and nightside auroral oval by three all-sky imagers, two Super Dual Auroral Radar Network (SuperDARN) radars, and Defense Meteorological Satellite Program (DMSP)-17. This data set revealed that a dayside poleward moving auroral form (PMAF) evolved into a polar cap airglow patch that propagated across the polar cap and then nightside poleward boundary intensifications (PBIs). SuperDARN observations detected fast antisunward flows associated with the PMAF, and the DMSP satellite, whose conjunction occurred within a few minutes after the PMAF initiation, measured enhanced low-latitude boundary layer precipitation and enhanced plasma density with a strong antisunward flow burst. The polar cap patch was spatially and temporally coincident with a localized antisunward flow channel. The propagation across the polar cap and the subsequent PBIs suggests that the flow channel originated from dayside reconnection and then reached the nightside open-closed boundary, triggering localized nightside reconnection and flow bursts within the plasma sheet. © 2014. American Geophysical Union. All Rights Reserved.

DOI： 10.1002/2014GL060301

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Height-dependent ionospheric variations in the vicinity of nightside poleward expanding aurora after substorm onset 査読有り Open Access

Oyama, S; Miyoshi, Y; Shiokawa, K; Kurihara, J; Tsuda, TT; Watkins, BJ

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 5 ) 頁： 4146 - 4156 2014年5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

High-latitude ionospheric variations at times near auroral substorms exhibit large temporal variations in both vertical and horizontal extents. Statistical analysis was made of data from the European Incoherent Scatter UHF radar at Tromsø, Norway, and International Monitor for Auroral Geomagnetic Effects magnetometer for finding common features in electron density, ion and electron temperatures and relating these to currents and associated heating. This paper particularly focused on the height dependencies. Results show clear evidences of large electric field with corresponding frictional heating and Pedersen currents located just outside the front of the poleward expanding aurora, which typically appeared at the eastside of westward traveling surge. At the beginning of the substorm recovery phase, the ionospheric density had a large peak in the E region and a smaller peak in the F region. This structure was named as C form in this paper based on its shape in the altitude-time plot. The lower altitude density maximum is associated with hard auroral electron precipitation probably during pulsating aurora. We attribute the upper F region density maximum to local ionization by lower energy particle precipitation and/or long-lived plasma that is convected horizontally into the overhead measurement volume from the dayside hemisphere. Key Points Ionosphere near poleward moving aurora is studied using EISCAT data Joule energy is dissipated just outside the poleward expanding aurora Ionospheric density at early recovery phase has a double peak in height ©2014. American Geophysical Union. All Rights Reserved.

DOI： 10.1002/2013JA019704

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Pi2 pulsation simultaneously observed in the E and F region ionosphere with the SuperDARN Hokkaido radar 査読有り Open Access

Teramoto, M; Nishitani, N; Pilipenko, V; Ogawa, T; Shiokawa, K; Nagatsuma, T; Yoshikawa, A; Baishev, D; Murata, KT

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 119 巻 ( 5 ) 頁： 3444 - 3462 2014年5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 investigated Pi2 pulsations in the nightside ionosphere that began at 14:15 UT (2315 LT) on 11 July 2010, and they were observed with high-temporal (8 s) resolution by beam 4 of the Super Dual Auroral Radar Network (SuperDARN) Hokkaido radar. These pulsations were simultaneously observed in both the ground/sea scatter echoes reflected from the F region height and in ionospheric echoes from field-aligned irregularities in the sporadic Es region. They had the same period of 110 s and approximately no phase lag. From the radar observations and the International Geomagnetic Reference Field model, the amplitude of the eastward (EEW) component of the electric field of the Pi2 pulsations in the ionosphere was estimated ~8.0 mV/m in the F region and ~2.0 mV/m in the E region. Corresponding Pi2 pulsations appeared dominantly in the horizontal northward magnetic field component (H) at nearby ground stations, Moshiri (MSR), St. Paratunka (PTK), and Stecolny (STC), with amplitudes ranging from 6 nT (MSR) to 10 nT (STC). At the dominant frequency of 8.8 mHz, the coherences between H and EEW were high (>0.9), the cross phases of EEW relative to H were -56° and -45°, and the amplitude ratios were 2.7 × 105 m/s and 8.4 × 105 m/s, in the E and F regions, respectively. Based on a comparison of these results with theoretical predictions, we suggest that the concept of a pure cavity mode is not sufficient to explain the combined observations for midlatitude Pi2 waves and that the contribution of an Alfvén waves must be taken in account. Key Points Midlatitude SuperDARN radar observed Pi2 pulsations in the E and F regions The electric field of Pi2 pulsations in the ionosphere are estimated The conception of pure cavity mode is not sufficient ©2014. American Geophysical Union. All Rights Reserved.

DOI： 10.1002/2012JA018585

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