Faculty Profiles - SHIOKAWA, Kazuo

Papers - SHIOKAWA, Kazuo

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プラズマバブルに伴う全電子数変化率・ロック損失分布 : ロック損失発生の有無と全電子数変化率の相関 Reviewed

菊地隼人, 中田裕之, 津川卓也, 大塚雄一, 西岡未知, 鷹野敏明, 島倉信, 塩川和夫, 小川忠彦

大気電気学会誌 = / Society of Atmospheric Electricity of Japan Vol. 4 ( 2 ) page： 80 - 81 2010.10

Simultaneous FAST and Double Star TC1 observations of broadband electrons during a storm time substorm Reviewed

A. Nakajima, K. Shiokawa, K. Seki, R. Nakamura, K. Keika, W. Baumjohann, T. Takada, J. P. McFadden, C. W. Carlson, A. N. Fazakerley, H. Reme, I. Dandouras, R. J. Strangeway, O. Le Contel, N. Cornilleau-Wehrlin, K. H. Yearby

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 115 2010.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Broadband electrons (BBEs) exhibit remarkable electron flux enhancements over a broad energy range (0.03-30 keV) near the equatorward edge of the auroral oval during geomagnetic storms. Here, we report a BBE event observed by the Fast Auroral Snapshot (FAST) satellite at 1355-1359 UT, similar to 61 degrees-66 degrees invariant latitudes, similar to 0600 magnetic local time (MLT), and similar to 3800 km altitude during a storm on 25 July 2004. The Double Star (DS) TC1 satellite was located near the magnetic equator at L = 5.7, close to the same local time as FAST. We investigate the acceleration process of BBEs from the inner magnetosphere to near the ionosphere by comparing electron data obtained by FAST and DS TC1. We also investigate both plasma and field variations in the inner magnetosphere associated with substorm onset using DS TC1 data to examine the relationship between the BBEs and the storm time substorm. Ground geomagnetic field data show a positive H-bay at similar to 1349 UT at similar to 0600 MLT, indicating that a storm time substorm started just before the appearance of the BBEs. At similar to 1350 UT, a tailward ion flow was observed by DS TC1. Then, DS TC1 observed a local dipolarization and a drastic ion density enhancement at similar to 1351 UT, indicating that particle heating associated with the substorm was occurring in the inner magnetosphere. From similar to 1352 UT, electron fluxes were isotropically enhanced at energies above similar to 0.5 keV as observed by DS TC1. On the other hand, the pitch angle distribution of BBEs at the FAST altitude showed field-aligned lower-energy electrons below similar to 0.5 keV and isotropic higher-energy electrons above similar to 0.5 keV. From these data, it was inferred that the BBEs might consist of two energy components due to the acceleration or heating of electrons at different altitudes in association with the storm time substorm.

DOI： 10.1029/2009JA014907

Web of Science

プラズマバブルに伴うGPSロック損失・全電子数変化率分布のマルチイベント解析 Reviewed

菊地隼人, 中田裕之, 津川卓也, 大塚雄一, 鷹野敏明, 島倉信, 塩川和夫, 小川忠彦

大気電気学会誌 = / Society of Atmospheric Electricity of Japan Vol. 4 ( 1 ) page： 58 - 59 2010.4

Rayleigh-Taylor type instability in auroral patches Reviewed

K. Shiokawa, A. Nakajima, A. Ieda, K. Sakaguchi, R. Nomura, T. Aslaksen, M. Greffen, E. Donovan

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 115 2010.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Based on observations by a high-resolution narrow field-of-view CCD camera, we found small-scale (5-25 km) finger-like structures at the western boundary of auroral patches in images obtained at Gillam (geomagnetic latitude: 65.5 degrees N), Canada, in January 2008. Since shear motion was not observed along the boundary of the patches, we suggest that these structures are formed by macroscopic Rayleigh-Taylor type plasma instability arising in the magnetospheric equatorial plane from the force balancing of the (eastward) magnetic tension force and the (westward) pressure gradient force.

DOI： 10.1029/2009JA014273

Web of Science

A physical mechanism of positive ionospheric storms at low latitudes and midlatitudes Reviewed

Balan N., Shiokawa K., Otsuka Y., Kikuchi T., Lekshmi D. Vijaya, Kawamura S., Yamamoto M., Bailey G. J.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 115 2010.2

Reorganization of polar cap patches through shears in the background plasma convection Reviewed

Hosokawa K., St-Maurice J. -P., Sofko G. J., Shiokawa K., Otsuka Y., Ogawa T.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 115 2010.1

The STEL induction magnetometer network for observation of high-frequency geomagnetic pulsations Reviewed

K. Shiokawa, R. Nomura, K. Sakaguchi, Y. Otsuka, Y. Hamaguchi, M. Satoh, Y. Katoh, Y. Yamamoto, B. M. Shevtsov, S. Smirnov, I. Poddelsky, M. Connors

EARTH PLANETS AND SPACE Vol. 62 ( 6 ) page： 517 - 524 2010

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER HEIDELBERG

The Solar-Terrestrial Environment Laboratory (STEL) induction magnetometer network has been developed to investigate the propagation characteristics of high-frequency geomagnetic pulsations in the Pc1 frequency range (0.2-5 Hz). Five induction magnetometers were installed in the period 2005-2008 at Athabasca in Canada, Magadan and Paratunka in Far East Russia, and Moshiri and Sata in Japan. The sensitivity of these magnetometers is between 0.3 and 13 V/nT at turnover frequencies of 1.7-5.5 Hz. GPS time pulses are used for accurate triggering of the 64-Hz data sampling. We show examples of PiB/Pc1 magnetic pulsations observed at these five stations, as well as the harmonic structure of ionospheric Alfven resonators observed at Moshiri. We found that the Pc1 packets are slightly modulated as they propagate from high to low latitudes in the ionospheric duct. These network observations are expected to contribute to our understanding of Pc1-range magnetic pulsations and their interaction with relativistic electrons by combining the obtained results with future satellite missions that observe radiation belt particles.

DOI： 10.5047/eps.2010.05.003

Web of Science

Scopus

Erratum: Geospace Exploration Mission: ERG Project

MIYOSHI Yoshizumi, SEKI Kanako, SHIOKAWA Kazuo, ONO Takayuki, KASABA Yasumasa, KUMAMOTO Atsushi, HIRAHARA Masafumi, TAKASHIMA Takeshi, ASAMURA Kazushi, MATSUOKA Ayako, NAGATSUMA Tsutomu, Working Group ERG

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN Vol. 8 ( ists27 ) page： Tm_13 2010

Language：English Publishing type：Research paper (scientific journal) Publisher：THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

This paper describes a small-satellite mission for geospace exploration ERG (Energization and Radiation in Geospace) that aims at understanding the acceleration process of relativistic electrons and dynamical variations of the space storm. The project consists of not only the satellite mission but also ground-based observations and integrated studies/simulation teams. The satellite will be launched into the inner magnetosphere around the next solar maximum. In efforts to understand the cross-energy coupling process that is essential to generate relativistic electrons and the dynamical evolution of space storms, the satellite is equipped with instruments for comprehensively observing plasma/particles, fields and waves. Possible international collaborations are also discussed in this paper.

DOI： 10.2322/tastj.8.tm_13

CiNii Research

Geospace Exploration Mission: ERG Project Reviewed

MIYOSHI Yoshizumi, MATSUOKA Ayako, NAGATSUMA Tsutomu, Working Group ERG, SEKI Kanako, SHIOKAWA Kazuo, ONO Takayuki, KASABA Yasumasa, KUMAMOTO Atsushi, HIRAHARA Masafumi, TAKASHIMA Takeshi, ASAMURA Kazushi

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN Vol. 8 ( 27 ) page： Tm_1-Tm_6 2010

Calculation of the parameter η krassovsky airglow emissions from the O2 (0-1) and OH (6-2) Reviewed Open Access

Amelia Naomi Onohara, Hisao Takahashi, Delano Gobbi, Kazuo Shiokawa

Revista Brasileira de Geofisica Vol. 28 ( 4 ) page： 579 - 592 2010

Language：Portuguese Publishing type：Research paper (scientific journal) Publisher：Sociedade Brasileira de Geofisica

In this work, the Krassovsky's η parameter, was used to investigate the amplitudes and phases of periodic variations of O2(0-1) and OH(6-2) airglow emissions. The data set was obtained from photometer measurements at Rikubetsu (43.5°N, 143.8°E), Japan, from March 2004 to August 2005, under collaboration with STEL-LAB (Solar-Terrestrial Environment Laboratory), Nagoya University. The results showed |η| = 5.3 ± 1.7 and Φ = -40.2°± 30.6° for O2 emission, and {pipe}η{pipe} = 8.0 ± 4.7 and Φ = -41.9°± 41.4° for OH emission. There is a good agreement between the results obtained in this work with the previous results. But, it must be emphasized that the models for Φ don't predict the results as good as the models for |η|. It was found the existence of larger |η| values for the OH emission, so that there are few results in literature concerning of this high values. Comparing it with the models of Schubert et al. (1991), it was observed that they have good correlation with the model for a gravity wave with a horizontal wavelength of 100 km. © 2010 Sociedade Brasileira de Geofísica.

DOI： 10.1590/S0102-261X2010000400004

Open Access

Scopus

Lower-thermospheric wind fluctuations measured with an FPI during pulsating aurora at Tromso, Norway Reviewed

S. Oyama, K. Shiokawa, J. Kurihara, T. T. Tsuda, S. Nozawa, Y. Ogawa, Y. Otsuka, B. J. Watkins

ANNALES GEOPHYSICAE Vol. 28 ( 10 ) page： 1847 - 1857 2010

Language：English Publishing type：Research paper (scientific journal) Publisher：COPERNICUS GESELLSCHAFT MBH

Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI) at a wavelength of 557.7 nm, an all-sky camera at a wavelength of 557.7 nm, and the European Incoherent Scatter (EISCAT) UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2) campaign in January 2009. This paper concentrated on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found in a darker area that appeared within the pulsating aurora. During the same time period, the EISCAT radar observed sporadic enhancements in the F-region backscatter echo power, which suggests the presence of low-energy electron (1 keV or lower) precipitation coinciding with increase in amplitude of the electromagnetic wave (at the order of 10 Hz or higher). While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during the pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.

DOI： 10.5194/angeo-28-1847-2010

Web of Science

Scopus

Telescope of Extreme Ultraviolet boarded on KAGUYA: Science from the Moon Reviewed

Yoshikawa, I, Murakami, G, Ezawa, F, Yoshioka, K, Obana, Y, Taguchi, M, Yamazaki, A, Kameda, S, Nakamura, M, Kikuchi, M, Kagitani, M, Okano, S, Shiokawa, K, Miyake, W

Advances in Geosciences Vol. 19 page： 109 - 121 2010

Language：English Publishing type：Research paper (scientific journal)

We have succeeded in observations by the Telescope of Extreme Ultraviolet (TEX) aboard Japan's lunar orbiter KAGUYA to characterize the evolution of the Earth's plasmasphere. The view afforded by the KAGUYA orbit encompasses the plasma distribution in a single exposure, enabling us to examine for the first time the globally-averaged properties of the plasmasphere from the side (meridian) view. We focus on a study period that began with a likely moderate erosion event of plasma patches in a geomagnetically disturbed period, and follow refilling of plasma from the upper ionosphere. The Earth's plasmasphere grew up to saturated level at the rate of approximately 1,600 km per day to 4,800 km per day on the equatorial plane. From the “side view” of the Earth, a specific magnetic flux tube with cold dense plasmas was seen and likely moved to outer magnetosphere, even while geomagnetic activity was low. From the moon, we are studying the terrestrial plasmas in the vicinity of the Earth. This is called “Geoscience from the Moon”.

DOI： 10.1142/9789812838162_0009

Scopus

Azimuthal structures of ray auroras at the beginning of auroral substorms Reviewed

K. Sakaguchi, K. Shiokawa, E. Donovan

GEOPHYSICAL RESEARCH LETTERS Vol. 36 ( 23 ) 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

The time evolution of optical structures in brightening auroras was examined for two substorm events that occurred on January 15, 2008 and February 27, 2009. The onsets of both auroral substorms were captured in the field of view of an all-sky TV camera at Gillam, Canada. We found that in both cases, the brightening auroras formed vertical structures, or so-called 'ray auroras', which lined up longitudinally for several tens of seconds before luminosity increased sharply. The ray structure implies precipitating electrons accelerated over a broad energy range at substorm onset. Two dimensional Fourier transform analysis of the auroral images showed the ray auroras have characteristic wavenumbers and harmonics that develop within a few seconds of the initial brightening. These results suggest that dispersive Alfven waves containing turbulent parallel electric fields form in brightening regions at the beginning of auroral substorms. Citation: Sakaguchi, K., K. Shiokawa, and E. Donovan ( 2009), Azimuthal structures of ray auroras at the beginning of auroral substorms, Geophys. Res. Lett., 36, L23106, doi: 10.1029/2009GL041252.

DOI： 10.1029/2009GL041252

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Scopus

GPS total electron content variations associated with a polar cap arc Reviewed Open Access

P. T. Jayachandran, K. Hosokawa, J. W. MacDougall, S. Mushini, R. B. Langley, K. Shiokawa

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 114 ( 12 ) 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

We report an example of total electron content (TEC) variations, using Global Positioning System (GPS) measurements, associated with a polar cap arc detected by an all-sky imager and ionosonde at a polar cap station. During the transit of the arc, GPS signals along the arc length showed an increase of similar to 2 TEC units whereas GPS signals perpendicular to the arc showed only an increase of similar to 0.3 TEC units. This indicates that the GPS TEC variations associated with a polar cap arc are dependent on the geometry of the GPS raypaths with respect to the arc. Ionosonde measurements confirm that this arc was an E region feature at similar to 110 km with peak electron density of 5.4 x 10(11) el/m(3). Estimated speed of the arc using a GPS triangulation method was about 300 m/s.

DOI： 10.1029/2009JA014916

Web of Science

Scopus

Ionospheric and geomagnetic disturbances during the 2005 Sumatran earthquakes Reviewed

Alina Marie Hasbi, Mohammed Awad Momani, Mohd Alauddin Mohd Ali, Norbahiah Misran, Kazuo Shiokawa, Yuichi Otsuka, Kiyohumi Yumoto

JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS Vol. 71 ( 17-18 ) page： 1992 - 2005 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

This paper investigates the ionospheric and geomagnetic responses during the 28 March 2005 and 14 May 2005 Sumatran earthquakes using GPS and magnetometer stations located in the near zone of the epicenters. These events occurred during low solar and geomagnetic activity. TEC oscillations with periods of 5-10 min were observed about 10-24 min after the earthquakes and have horizontal propagation velocities of 922-1259 m/s. Ionospheric disturbances were observed at GPS stations located to the northeast of the epicenters, while no significant disturbances were seen relatively east and south of the epicenters. The magnetic field measurements show rapid fluctuations of 4-5 s shortly after the earthquake, followed by a Pc5 pulsation of 4.8 min about 11 min after the event. The correlation between the ionospheric and geomagnetic responses shows a good agreement in the period and time lag of the peak disturbance arrival, i.e. about 11-13 min after the earthquake. (C) 2009 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.jastp.2009.09.004

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Scopus

Spatial relationship of F-region field-aligned irregularities and medium-scale traveling ionospheric disturbances observed with the MU radar and all-sky airglow imagers Reviewed

Otsuka Y., Shiokawa K., Ogawa T., Yokoyama T., Yamamoto M.

ICCAS-SICE 2009 - ICROS-SICE International Joint Conference 2009, Proceedings page： 1310 - 1311 2009.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ICCAS-SICE 2009 - ICROS-SICE International Joint Conference 2009, Proceedings

We report simultaneous observations of medium-scale traveling ionospheric disturbances (MSTIDs) and field-aligned irregularities (FAIs) in the F region by using two all-sky airglow imagers and the MU radar in Japan. MSTIDs propagating southwestward were observed in 630-nm airglow images on the night of June 16, 2004. During this MSTID event, FAIs in the F region were observed by making multibeam measurements with the MU radar. We found that FAIs with intense (weak) signal-to-noise ratio (SNR) coincided with the airglow depletion (enhancement) caused by the MSTIDs. This result indicates that the FAIs could be generated by the gradient drift instability at the airglow depletion region. © 2009 SICE.

Scopus

The optical mesosphere thermosphere imagers (OMTIs) for network measurements of aurora and airglow Reviewed

Shiokawa K., Hosokawa K., Sakaguchi K., Ieda A., Otsuka Y., Ogawa T., Connors M.

AIP Conference Proceedings Vol. 1144 page： 212 - 215 2009.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AIP Conference Proceedings

The Optical Mesosphere Thermosphere Imagers (OMTIs) currently consist of eight all-sky cooled-CCD imagers and several interferometers and spectrometers. They are making routine observations of aurora and airglow in Japan, Australia, Indonesia, and Canada. Here we show recent results of OMTIs particularly from the two Canadian stations at Resolute Bay (RSB) and Athabasca (ATH). At RSB, we observe polar-cap plasma patches almost always during southward IMF periods. From two-dimensional cross-correlation analyses, we determine velocity vectors of the patches, which indicates the ionospheric convection vector, showing high correlation with the IMF-By and -Bz variations. At ATH, we often observe isolated proton arcs and Stable Auroral Red (SAR) arcs, which are located equatorward of the auroral oval. The appearance of the isolated proton arcs is highly correlated with the Pc 1 geomagnetic pulsations measured simultaneously at ATH, suggesting interactions between the electromagnetic ion cyclotron (EMIC) waves and protons in the vicinity of the plasmapause and the ring current. Similar interactions without waves are also suggested for the SAR arcs, which appear after the substorm expansion phase even without geomagnetic storms. These observations show promising capability to monitor magnetospheric processes from the ground stations, which would contribute to the future satellite projects, such as THEMIS, ERG, and Scope/Xscale. © 2009 American Institute of Physics.

DOI： 10.1063/1.3169292

Scopus

プラズマバブルに伴うGPSにおけるロック損失分布・全電子数変化率分布の時間変化 Reviewed

菊地隼人, 中田裕之, 津川卓也, 大塚雄一, 鷹野敏明, 島倉信, 塩川和夫, 小川忠彦

大気電気学会誌 = / Society of Atmospheric Electricity of Japan Vol. 3 ( 2 ) page： 68 - 69 2009.10

Coordinated observations of nighttime medium-scale traveling ionospheric disturbances in 630-nm airglow and HF radar echoes at midlatitudes Reviewed Open Access

S. Suzuki, K. Hosokawa, Y. Otsuka, K. Shiokawa, T. Ogawa, N. Nishitani, T. F. Shibata, A. V. Koustov, B. M. Shevtsov

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 114 ( 7 ) 2009.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

We investigate nighttime medium-scale traveling ionospheric disturbances (MSTIDs) using the SuperDARN HF radar at Hokkaido, Japan (43.5 degrees N, 143.6 degrees E), and an OI 630-nm airglow imager located at Paratunka, Russia (53.0 degrees N, 158.2 degrees E), within the radar field of view. The imager identified southwestward propagating MSTIDs with a horizontal wavelength of similar to 300 km on 8 December 2007. Throughout this event, the radar continuously detected ionospheric echoes originating from decameter-scale field-aligned irregularities (FAIs) at the F region heights. The Doppler velocities of these echoes showed systematic polarity changes which were consistent with airglow intensity variations. These polarity changes would be attributed to E x B plasma drifts caused by the polarization electric field embedded in the MSTIDs. The FAI echo powers also varied in agreement with the airglow intensity variations: strong (weak) echoes coincided with the airglow depletion (enhancement) region. Considering the MSTID polarization electric field, it is suggested that the observed FAIs were generated by the gradient drift instability on the bottomside of the F region.

DOI： 10.1029/2008JA013963

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Scopus

Spatial relationship of nighttime medium-scale traveling ionospheric disturbances and F region field-aligned irregularities observed with two spaced all-sky airglow imagers and the middle and upper atmosphere radar Reviewed Open Access

Otsuka Y, Shiokawa K, Ogawa T, Yokoyama T, Yamamoto M

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS Vol. 114 ( 5 ) 2009.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Blackwell Publishing Ltd

We report simultaneous observations of medium-scale traveling ionospheric disturbances (MSTIDs) and field-aligned irregularities (FAls) in the F region using two all-sky airglow imagers and the middle and upper atmosphere (MU) radar. MSTIDs propagating southwestward were observed simultaneously in 630-nm airglow images over Sakata (39.0°N, 139.9°E) and Shigaraki (34.90N, 136.1°E), Japan, on the night of 16 June 2004. By using all-sky images over both sites, we estimated the altitude of the airglow layer to be 260 km by the triangulation method. During the MSTID event, FAIs in the F region were observed by making multibeam measurements with the MU radar at Shigaraki. In order to investigate the spatial relationship between the MSTIDs and FAIs, the FAIs were mapped onto the 630-nm airglow layer (altitude, 260 km) along the geomagnetic field lines. We found that FAIs with an intense (weak) signal-to-noise ratio coincided with the airglow depletion (enhancement) caused by the MSTIDs. FAI velocity obtained from a combination of the Doppler velocities on the three radar beams oscillated in the northwest-southeast direction, with an amplitude of approximately 82 m/s. The FAI velocity was northwestward (southeastward) at the airglow depletion (enhancement). The directions of the FAI velocity were consistent with those of the ExB drifts caused by the polarized electric fields associated with the MSTIDs. The northeastward polarized electric field at the airglow depletion region strengthened the background eastward effective electric field and drove the gradient drift instability generating FAIs. This might be the reason why the FAIs preferred to occur at the airglow depletion region. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013902

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Scopus

Other Link： http://orcid.org/0000-0001-8392-6455

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Papers - SHIOKAWA, Kazuo