研究者詳細 - 塩川　和夫

論文 - 塩川　和夫

分割表示 483 件中 161 - 180 件目／全件表示 >>

A scheme for forecasting severe space weather

Balan N., Ebihara Y., Skoug R., Shiokawa K., Batista I. S., Ram S. Tulasi, Omura Y., Nakamura T., Fok M. -C.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 122 巻 ( 3 ) 頁： 2824-2835 2017年3月

Localized polar cap precipitation in association with nonstorm time airglow patches

Zou Ying, Nishimura Yukitoshi, Lyons Larry R., Shiokawa Kazuo

GEOPHYSICAL RESEARCH LETTERS 44 巻 ( 2 ) 頁： 609-617 2017年1月

On the effect of thermospheric neutral winds on post-midnight field-aligned irregularities at low latitudes 査読有り

Dao, T; Otsuka, Y; Shiokawa, K; Nishioka, M; Yamamoto, M; Buhari, SM; Abdullah, M; Husin, A

2017 XXXIIND GENERAL ASSEMBLY AND SCIENTIFIC SYMPOSIUM OF THE INTERNATIONAL UNION OF RADIO SCIENCE (URSI GASS) 2017-January 巻頁： 1 - 4 2017年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：2017 32nd General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2017

We investigated a post-midnight Field-Aligned Irregularities (FAIs) event observed with the Equatorial Atmosphere Radar (EAR) at Kototabang (0.2°S, 100.3°E, dip lat. 10.4°S) in Indonesia on the night of 9 July 2010, using a comprehensive dataset of both neutral and plasma parameters. We compared FAI echoes collocated with 630 nm airglow depletion detected by an all-sky imager. The thermospheric neutral winds and temperatures obtained by a Fabry-Perot interferometer at Kototabang and the altitudes of F-layer (h'F) observed with ionosondes at Kototabang, Chiang Mai, and Chumphon were also examined. We found that the 3-m scale post-midnight FAIs occurred within plasma bubbles. The convergence of the equatorward neutral winds happened in this particular event related to midnight temperature maximum (MTM) and that the equatorward winds in both northern and southern hemispheres could be responsible for the growth of plasma bubbles around midnight. The uplift of F-layer at low latitudes could increase the growth rate of the Rayleigh-Taylor instability. Eastward electric currents driven by the equatorward winds could also contribute to the generation of the irregularities at post-midnight.

DOI： 10.23919/URSIGASS.2017.8105106

Web of Science

Scopus

その他リンク： http://orcid.org/0000-0002-4957-764X

The first long-term all-sky imager observation of lunar sodium tail 査読有り

Nishino Masaki N., Shiokawa Kazuo, Otsuka Yuichi

ICARUS 280 巻頁： 199-204 2016年12月

Ionospheric TEC Weather Map Over South America 査読有り

Takahashi H., Wrasse C. M., Denardini C. M., Padua M. B., de Paula E. R., Costa S. M. A., Otsuka Y., Shiokawa K., Galera Monico J. F., Ivo A., Sant'Anna N.

SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS 14 巻 ( 11 ) 頁： 937 - 949 2016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：Space Weather

Ionospheric weather maps using the total electron content (TEC) monitored by ground-based Global Navigation Satellite Systems (GNSS) receivers over South American continent, TECMAP, have been operationally produced by Instituto Nacional de Pesquisas Espaciais's Space Weather Study and Monitoring Program (Estudo e Monitoramento Brasileiro de Clima Especial) since 2013. In order to cover the whole continent, four GNSS receiver networks, (Rede Brasileiro de Monitoramento Contínuo) RBMC/Brazilian Institute for Geography and Statistics, Low-latitude Ionospheric Sensor Network, International GNSS Service, and Red Argentina de Monitoreo Satelital Continuo, in total ~140 sites, have been used. TECMAPs with a time resolution of 10 min are produced in 12 h time delay. Spatial resolution of the map is rather low, varying between 50 and 500 km depending on the density of the observation points. Large day-to-day variabilities of the equatorial ionization anomaly have been observed. Spatial gradient of TEC from the anomaly trough (total electron content unit, 1 TECU = 1016 el m−2 (TECU) <10) to the crest region (TECU > 80) causes a large ionospheric range delay in the GNSS positioning system. Ionospheric plasma bubbles, their seeding and development, could be monitored. This plasma density (spatial and temporal) variability causes not only the GNSS-based positioning error but also radio wave scintillations. Monitoring of these phenomena by TEC mapping becomes an important issue for space weather concern for high-technology positioning system and telecommunication.

DOI： 10.1002/2016SW001474

Web of Science

Scopus

Localized field-aligned currents in the polar cap associated with airglow patches 査読有り

Zou Ying, Nishimura Yukitoshi, Burchill Johnathan K., Knudsen David J., Lyons Larry R., Shiokawa Kazuo, Buchert Stephan, Chen Steve, Nicolls Michael J., Ruohoniemi J. Michael, McWilliams Kathryn A., Nishitani Nozomu

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 10 ) 頁： 10172-10189 2016年10月

Heliospheric plasma sheet (HPS) impingement onto the magnetosphere as a cause of relativistic electron dropouts (REDs) via coherent EMIC wave scattering with possible consequences for climate change mechanisms 査読有り

Tsurutani B. T., Hajra R., Tanimori T., Takada A., Bhanu R., Mannucci A. J., Lakhina G. S., Kozyra J. U., Shiokawa K., Lee L. C., Echer E., Reddy R. V., Gonzalez W. D.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 10 ) 頁： 10130 - 10156 2016年10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

A new scenario is presented for the cause of magnetospheric relativistic electron decreases (REDs) and potential effects in the atmosphere and on climate. High-density solar wind heliospheric plasmasheet (HPS) events impinge onto the magnetosphere, compressing it along with remnant noon-sector outer-zone magnetospheric ~10-100 keV protons. The betatron accelerated protons generate coherent electromagnetic ion cyclotron (EMIC) waves through a temperature anisotropy (T⊥/T|| > 1) instability. The waves in turn interact with relativistic electrons and cause the rapid loss of these particles to a small region of the atmosphere. A peak total energy deposition of ~3 × 1020 ergs is derived for the precipitating electrons. Maximum energy deposition and creation of electron-ion pairs at 30-50 km and at < 30 km altitude are quantified. We focus the readers' attention on the relevance of this present work to two climate change mechanisms. Wilcox et al. (1973) noted a correlation between solar wind heliospheric current sheet (HCS) crossings and high atmospheric vorticity centers at 300 mb altitude. Tinsley et al. () has constructed a global circuit model which depends on particle precipitation into the atmosphere. Other possible scenarios potentially affecting weather/climate change are also discussed.

DOI： 10.1002/2016JA022499

Web of Science

Scopus

Spectral characteristics of steady quiet-time EMIC waves observed at geosynchronous orbit 査読有り

Kim Khan-Hyuk, Park Jong-Sun, Omura Yoshiharu, Shiokawa Kazuo, Lee Dong-Hun, Kim Gi-Jeong, Jin Ho, Lee Ensang, Kwon Hyuck-Jin

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 9 ) 頁： 8640-8660 2016年9月

A proposal on the study of solar-terrestrial coupling processes with atmospheric radars and ground-based observation network 査読有り

Tsuda Toshitaka, Yamamoto Mamoru, Hashiguchi Hiroyuki, Shiokawa Kazuo, Ogawa Yasunobu, Nozawa Satonori, Miyaoka Hiroshi, Yoshikawa Akimasa

RADIO SCIENCE 51 巻 ( 9 ) 頁： 1587-1599 2016年9月

Quasi-periodic rapid motion of pulsating auroras 査読有り

Fukuda Yoko, Kataoka Ryuho, Miyoshi Yoshizumi, Katoh Yuto, Nishiyama Takanori, Shiokawa Kazuo, Ebihara Yusuke, Hampton Donald, Iwagami Naomoto

POLAR SCIENCE 10 巻 ( 3 ) 頁： 183-191 2016年9月

Fast modulations of pulsating proton aurora related to subpacket structures of Pc1 geomagnetic pulsations at subauroral latitudes 査読有り

Ozaki M., Shiokawa K., Miyoshi Y., Kataoka R., Yagitani S., Inoue T., Ebihara Y., Jun C. -W, Nomura R., Sakaguchi K., Otsuka Y., Shoji M., Schofield I., Connors M., Jordanova V. K.

GEOPHYSICAL RESEARCH LETTERS 43 巻 ( 15 ) 頁： 7859 - 7866 2016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

To understand the role of electromagnetic ion cyclotron (EMIC) waves in determining the temporal features of pulsating proton aurora (PPA) via wave-particle interactions at subauroral latitudes, high-time-resolution (1/8 s) images of proton-induced N2+ emissions were recorded using a new electron multiplying charge-coupled device camera, along with related Pc1 pulsations on the ground. The observed Pc1 pulsations consisted of successive rising-tone elements with a spacing for each element of 100 s and subpacket structures, which manifest as amplitude modulations with a period of a few tens of seconds. In accordance with the temporal features of the Pc1 pulsations, the auroral intensity showed a similar repetition period of 100 s and an unpredicted fast modulation of a few tens of seconds. These results indicate that PPA is generated by pitch angle scattering, nonlinearly interacting with Pc1/EMIC waves at the magnetic equator.

DOI： 10.1002/2016GL070008

Web of Science

Scopus

Direct observational evidence for the merging of equatorial plasma bubbles 査読有り

Narayanan V. L., Gurubaran S., Shiokawa K.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 8 ) 頁： 7923 - 7931 2016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: Space Physics

In this work we present direct ground-based observational evidence for the merging of individual equatorial plasma bubbles (EPBs) obtained through the imaging of OI 630.0 nm airglow. Three potential mechanisms have been identified: (1) One of the EPBs tilts and reaches location of the adjacent growing EPB finally merging with it. (2) Some of the branches of an EPB arising from secondary instabilities reach out to adjacent EPB and merge with it. (3) The eastward zonal drift of the EPB on the eastern side slows down while the adjacent EPB on the western side drifts relatively faster and catches up. In one of the cases, a branch of an EPB was observed to get interchanged with another EPB as a result of merging and consequent pinching off from the parent EPB.

DOI： 10.1002/2016JA022861

Web of Science

Scopus

Shrinking equatorial plasma bubbles 査読有り

Narayanan V. L., Gurubaran S., Shiokawa K., Emperumal K.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 7 ) 頁： 6924 - 6935 2016年7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 formation of equatorial plasma bubbles (EPBs) associated with spread F irregularities are fairly common phenomenon in the postsunset equatorial ionosphere. These bubbles grow as a result of eastward polarization electric field resulting in upward E × B drift over the dip equator. As they grow they are also mapped to low latitudes along magnetic field lines. The EPBs are often observed as airglow depletions in the images of OI 630 nm emission. On occasions the growth of the features over the dip equator is observed as poleward extensions of the depletions in all-sky images obtained from low latitudes. Herein, we present interesting observations of decrease in the latitudinal extent of the EPBs corresponding to a reduction in their apex altitudes over the dip equator. Such observations indicate that these bubbles not only grow but also shrink on occasions. These are the first observations of shrinking EPBs. The observations discussed in this work are based on all-sky airglow imaging observations of OI 630.0 nm emission made from Panhala (11.1°N dip latitude). In addition, ionosonde observations made from dip equatorial site Tirunelveli (1.1°N dip latitude) are used to understand the phenomenon better. The analysis indicates that the speed of shrinking occurring in the topside is different from the bottomside vertical drifts. When the EPBs shrink, they might decay before sunrise hours.

DOI： 10.1002/2016JA022633

Web of Science

Scopus

ELF/VLF wave propagation at subauroral latitudes: Conjugate observation between the ground and Van Allen Probes A 査読有り

Martinez-Calderon Claudia, Shiokawa Kazuo, Miyoshi Yoshizumi, Keika Kunihiro, Ozaki Mitsunori, Schofield Ian, Connors Martin, Kletzing Craig, Hanzelka Miroslav, Santolik Ondrej, Kurth William S.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 6 ) 頁： 5384-5393 2016年6月

Special issue "The 12th International Conference on Substorms"

Shiokawa Kazuo, Fok Mei-Ching, Fujimoto Masaki

EARTH PLANETS AND SPACE 68 巻 2016年5月

Possible generation mechanisms for Pc1 pearl structures in the ionosphere based on 6 years of ground observations in Canada, Russia, and Japan 査読有り

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

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 5 ) 頁： 4409-4424 2016年5月

An evidence for prompt electric field disturbance driven by changes in the solar wind density under northward IMF Bz condition 査読有り

Rout Diptiranjan, Chakrabarty D., Sekar R., Reeves G. D., Ruohoniemi J. M., Pant Tarun K., Veenadhari B., Shiokawa K.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 5 ) 頁： 4800 - 4810 2016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

Before the onset of a geomagnetic storm on 22 January 2012 (Ap = 24), an enhancement in solar wind number density from 10/cm3 to 22/cm3 during 0440–0510 UT under northward interplanetary magnetic field (IMF Bz) condition is shown to have enhanced the high-latitude ionospheric convection and also caused variations in the geomagnetic field globally. Conspicuous changes in ΔX are observed not only at longitudinally separated low-latitude stations over Indian (prenoon), South American (midnight), Japanese (afternoon), Pacific (afternoon) and African (morning) sectors but also at latitudinally separated stations located over high and middle latitudes. The latitudinal variation of the amplitude of the ΔX during 0440–0510 UT is shown to be consistent with the characteristics of prompt penetration electric field disturbances. Most importantly, the density pulse event caused enhancements in the equatorial electrojet strength and the peak height of the F layer (hmF2) over the Indian dip equatorial sector. Further, the concomitant enhancements in electrojet current and F layer movement over the dip equator observed during this space weather event suggest a common driver of prompt electric field disturbance at this time. Such simultaneous variations are found to be absent during magnetically quiet days. In absence of significant change in solar wind velocity and magnetospheric substorm activity, these observations point toward perceptible prompt electric field disturbance over the dip equator driven by the overcompression of the magnetosphere by solar wind density enhancement.

DOI： 10.1002/2016JA022475

Web of Science

Scopus

Lower thermospheric wind variations in auroral patches during the substorm recovery phase 査読有り

Oyama Shin-ichiro, Shiokawa Kazuo, Miyoshi Yoshizumi, Hosokawa Keisuke, Watkins Brenton J., Kurihara Junichi, Tsuda Takuo T., Fallen Christopher T.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 4 ) 頁： 3564-3577 2016年4月

Coordinated observations of F region 3m field-aligned plasma irregularities associated with medium-scale traveling ionospheric disturbances 査読有り

Lin F. F., Wang C. Y., Su C. L., Shiokawa K., Saito S., Chu Y. H.

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 121 巻 ( 4 ) 頁： 3750 - 3766 2016年4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

Three meter field-aligned irregularities (3 m FAIs) associated with medium-scale traveling ionospheric disturbances (MSTIDs) that occurred on 5 February 2008 were observed by using the Chung-Li 52 MHz coherent scatter radar. Interferometry measurements show that the plasma structures responsible for the 3 m FAI echoes are in a clumpy shape with a horizontal dimension of about 10-78 km in a height range of 220-300 km. In order to investigate the dynamic behaviors of the plasma irregularities at different scales in the bottomside of F region, the VHF radar echo structures from the 3 m FAIs combined with the 630 nm airglow images provided by the Yonaguni all-sky imager are compared and analyzed. The results show that the radar echoes were located at the west edge of the depletion zones of the 630 nm airglow image of the MSTIDs. The bulk echo structures of the 3 m FAIs drifted eastward at a mean trace velocity of about 30 m/s that is in general agreement with the zonal trace velocity of the MSTIDs shown in the 630 nm airglow images. These results suggest that the observed F region 3 m FAIs for the present case can be regarded as the targets that are frozen in the local region of the MSTIDs. In addition, the radar-observed 3 m FAI echo intensity and spectral width bear high correlations to the percentage variations of the 630 nm emission intensity. These results seem to suggest that through the nonlinear turbulence cascade process, the MSTID-associated 3 m FAIs are very likely generated from the kilometer-scale plasma irregularities with large amplitude excited by the gradient drift instability.

DOI： 10.1002/2016JA022511

Web of Science

Scopus

Special issue "International CAWSES-II Symposium"

Yamamoto Mamoru, Shiokawa Kazuo, Nakamura Takuji, Gopalswamy Nat

EARTH PLANETS AND SPACE 68 巻 2016年2月

　前のページ - 次のページ　

<塩川 和夫>

論文 - 塩川 和夫

<塩川　和夫>

論文 - 塩川　和夫