研究者詳細 - 塩川　和夫

論文 - 塩川　和夫

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Motion of polar cap patches: A statistical study with all-sky airglow imager at Resolute Bay, Canada 査読有り

Hosokawa, K; Kashimoto, T; Suzuki, S; Shiokawa, K; Otsuka, Y; Ogawa, T

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 4 ) 2009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

A highly sensitive all-sky airglow imager (part of the Optical Mesosphere Thermosphere Imagers [OMTIs]) has been operating for 3 years at Resolute Bay, Canada (geographic latitude 74.7°N; geomagnetic latitude 82.9°N) since January 2005. One of its major applications is the observation of polar cap patches. Polar cap patches are generated in the vicinity of the cusp during southward interplanetary magnetic field (IMF) conditions, and they exhibit dynamic movement, possibly in association with the changes in the IMF orientation. In order to determine how their motions are controlled by the upstream IMF conditions, we applied a motion-tracking algorithm that was based on two-dimensional cross-correlation analysis to consecutive images obtained from January 2005 to December 2007 by the all-sky airglow imager at Resolute Bay. We identified and extracted 561 individual patches and then carried out a statistical study of their motion. It is demonstrated that the speed of patches is primarily controlled by the IMF Bz. Furthermore, the dawn-dusk component of the patch drift velocities is well correlated with the IMF B y, which is in good agreement with the published By dependence of the nightside polar cap convection. This enables us to monitor the plasma convection within the polar cap by using polar cap patches as tracers. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA014020

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Unusually elongated, bright airglow plume in the polar cap F region: Is it a tongue of ionization? 査読有り

Hosokawa K., Tsugawa T., Shiokawa K., Otsuka Y., Ogawa T., Hairston M. R.

GEOPHYSICAL RESEARCH LETTERS 36 巻 ( 7 ) 2009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：Geophysical Research Letters

[1] We report an event of unusually elongated, bright airglow plume, which is considered as an optical manifestation of tongue of ionization (TOI) in the central polar cap. This optical structure was detected with an all-sky airglow imager at Resolute Bay (74.73°N, 265.07°E) during a large magnetic storm on December 15, 2006. The absolute optical intensity of the plume was ≈ kR, which is much brighter than that of non-stormtime polar cap patches. Two-dimensional imaging capability of the all-sky imager demonstrates that some meso-scale structures (≈250-600 km) were embedded within the plume. Simultaneous ion density and drift measurements with the DMSP spacecraft strongly suggest that the plume was extending from the dayside as a narrow stream of dense plasma and thus is an optical manifestation of polar cap TOI. The DMSP data also implies that the possible source of the plume is a narrow stream of storm enhanced density (SED) transported from lower latitudes. The DMSP auroral particle observation demonstrates that the polar cap extremely expanded equatorward during this interval. This extreme expansion allowed the anti-sunward convection to capture plasmas within the SED and deliver them deep into the polar cap as a luminous airglow plume. This observation claims that the plasma transport from the dayside lower latitudes plays an important role in controlling the plasma environment in the polar cap ionosphere during magnetic storms. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2009GL037512

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Medium-scale traveling ionospheric disturbances observed with the SuperDARN Hokkaido radar, all-sky imager, and GPS network and their relation to concurrent sporadic <i>E</i> irregularities 査読有り

Ogawa, T; Nishitani, N; Otsuka, Y; Shiokawa, K; Tsugawa, T; Hosokawa, K

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 3 ) 2009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

We present midlatitude medium-scale traveling ionospheric disturbances (MSTIDs) observed with a Super Dual Auroral Radar Network (SuperDARN) HF radar at around 10 MHz in Hokkaido, Japan, in combination with a 630-nm all-sky imager and a GPS network (GEONET) that provides total electron content (TEC) data. MSTIDs propagating southward from high latitudes are detected at first with the HF radar and then with the imager and GEONET. We analyze two MSTID events, one in winter (event 1) and the other in summer (event 2), to find that MSTIDs appear simultaneously, at least, at 55°-25°N. It is shown that nighttime MSTIDs propagate toward the southwest over a horizontal distance of about 4000 km, and daytime MSTIDs do so toward the southeast. Daytime radar echoes are due to ground/sea surface (GS) scatter, while nighttime echoes in event 1 return from 15-m-scale F region field-aligned irregularities (FAIs) and those in event 2 are due to GS scatter. Doppler velocities of the nighttime F region FAI echoes in event 1 are negative (motion away from the radar) within strong echo regions and are positive (motion toward the radar) within weak echo regions. This fact suggests that the strong (weak) echoes return from suppressed (enhanced) airglow/TEC areas, in line with previous observations over central Japan. The nighttime MSTIDs in events 1 and 2 are often accompanied by concurrent coherent echoes from FAIs in sporadic E (Es) layers. The Es echo areas in event 2 rather coincide with suppressed airglow/TEC areas in the F region that are connected with the echo areas along the geomagnetic field, indicating the existence of E and F region coupling at night. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013893

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Super plasma fountain and equatorial ionization anomaly during penetration electric field 査読有り Open Access

Balan, N; Shiokawa, K; Otsuka, Y; Watanabe, S; Bailey, GJ

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 3 ) 2009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

Relative importance of diffusion, electric field, and neutral wind on equatorial plasma fountain and equatorial ionization anomaly (EIA) during a strong daytime eastward prompt penetration electric field (PPEF) event are evaluated using the Sheffield University Plasmasphere Ionosphere Model and the recorded PPEF during the super geomagnetic storm of 9 November 2004. The fountain rapidly develops into a super fountain during the PPEF event. The super fountain becomes strong with less poleward turning of the velocity vectors in the presence of an equatorward wind that reduces (or stops) the downward velocity component due to diffusion and raises the ionosphere to high altitudes of reduced chemical loss. The EIA crests in peak electron density and total electron content shift rapidly to higher than normal latitudes during the PPEF event. However, the crests become stronger than normal only in the presence of an equatorward wind. The results suggest that the presence of an equatorward neutral wind is required to produce a strong positive ionospheric storm during, a daytime eastward PPEF event. The equatorward neutral wind need not be a storm time wind though stronger wind can lead to stronger ionospheric storms. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013768

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Relationship between polar cap patches and field-aligned irregularities as observed with an all-sky airglow imager at Resolute Bay and the PolarDARN radar at Rankin Inlet 査読有り Open Access

Hosokawa, K; Shiokawa, K; Otsuka, Y; Ogawa, T; St-Maurice, JP; Sofko, GJ; Andre, DA

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 3 ) 2009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

Simultaneous two-dimensional observations of airglow enhancement and radar backscatter from field-aligned irregularities (FAIs) associated with polar cap patches were conducted. The spatial structure of 630 nm airglow from polar cap patches was imaged using an all-sky airglow imager at Resolute Bay, Canada, while backscatter echoes from decameter-scale FAIs were observed using the newly constructed HF Polar Dual Auroral Radar Network (PolarDARN) radar at Rankin Inlet, Canada. Both the airglow enhancement and the radar backscatter appeared within a structured region with the spatial extent of about 500-1000 km. The decameter-scale FAIs were found to extend over the entire region of airglow enhancement associated with polar cap patches, indicating that the polar patch plasma became almost fully structured soon after initiation (within approximately 2025 min). These findings imply that some rapid structuring process of the entire patch area is involved in addition to the primary gradient-drift instabilities. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013707

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Measurements of geomagnetically induced current in a power grid in Hokkaido, Japan 査読有り

Watari S., Kunitake M., Kitamura K., Hori T., Kikuchi T., Shiokawa K., Nishitani N., Kataoka R., Kamide Y., Aso T., Watanabe Y., Tsuneta Y.

SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS 7 巻 ( 3 ) 頁： S03002 2009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：Space Weather

There have been numerous reports showing that space weather affects power grids through a geomagnetically induced current (GIC). Generally, power grids consist of power lines connected to transformers, of which neutral points are directly grounded. The GIC flows into those transformers through the neutral points if geomagnetic variations cause a ground level potential. These currents can damage power grids, especially transformers. It has been tacitly assumed, however, that the effect of the GIC is minor in Japan because of the country's location at geomagnetically lower latitudes. To examine the GIC effect in Japan, we conducted approximately 2 years of GIC measurements in Hokkaido, Japan. It is found that GICs associated with substorms can be detected in Japan even at the solar minimum although intense GICs do occur mostly during geomagnetic storms. Temporal variations of GICs show high correlation with geomagnetic field variations, rather than time derivatives of the geomagnetic field. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008SW000417

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その他リンク： http://orcid.org/0000-0001-8451-6941

赤道プラズマバブルに伴うGPSでのロック損失と全電子数変化率分布査読有り

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 3 巻 ( 1 ) 頁： 126 - 127 2009年3月

Medium-Scale Traveling Ionospheric Disturbances and Plasma Bubbles Observed by an All-Sky Airglow Imager at Yonaguni, Japan 査読有り

Ogawa Tadahiko, Otsuka Yuichi, Shiokawa Kazuo, Tsugawa Takuya, Saito Akinori, Hoshinoo Kazuaki, Matunaga Keisuke, Kubota Minoru, Ishii Mamoru

TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES 20 巻 ( 1 ) 頁： 287 - 295 2009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：Terrestrial, Atmospheric and Oceanic Sciences

We report on nighttime airglow imaging observations of the low latitude ionosphere by means of a 630-m all-sky imager installed in March 2006 at Yonaguni. Japan (24.5°N. 123.0°E; 14.6°N geomagnetic). about 100 km east of Taiwan. The imager detected medium-scale traveling ionospheric disturbances (MSTIDs) for about 7 hours on the night of 26 May 2006. A dense GPS network in Japan also observed the same MSTID event on this night. The imager and GEONET data indicate that most of the MSTIDs propagated southwestward from the north of Japan to the south of Yonaguni and Taiwan over 4000 km. with a southern limit of 19°N (geomagnetic latitude 9°N) or lower. On the night of 10 November 2006. the imager observed two weak emission bands that were embedded on the F-region anomaly crest to the south of Yonaguni. The simultaneous electron density profiles from the FORMOSAT-3/COSMIC mission demonstrate that the weak emission bands are due to density depletions in equatorial plasma bubbles. These case studies suggest that the Yonaguni imager in collaboration with other instruments is very suitable for the study of ionospheric disturbances in and around the northern F-region anomaly crest.

DOI： 10.3319/TAO.2007.12.06.02(F3C)

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Statistical characteristics of polar cap mesospheric gravity waves observed by an all-sky airglow imager at Resolute Bay, Canada 査読有り

Suzuki, S; Shiokawa, K; Hosokawa, K; Nakamura, K; Hocking, WK

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 1 ) 2009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: Space Physics

An airglow imager at Resolute Bay, Canada (74.7°N, 265.1°E) has been used for the observation of gravity waves in the polar cap mesosphere since January 2005. On the basis of the long-term imaging observations obtained over 137 nights during the winter seasons of 2005 and 2006, we extracted 143 events of small-scale (<100 km) gravity waves from sequential sodium airglow (589.3 nm) images. The observed waves typically had horizontal wavelengths of 20-50 km and phase speeds of 30-60 ms-1. The propagation directions were predominantly westward. We also identified larger-scale (>100 km) gravity waves using airglow keograms, which represent a time series of the horizontal cross sections of the airglow images. The horizontal wavelengths and phase speeds of the large-scale waves were typically 100-400 km and 60-100 ms -1, respectively. The propagation directions of these large-scale waves also showed a westward preference. The wave parameters appeared to have no relation with the geomagnetic activities represented by the Kp index. On the other hand, the propagation directions of the observed waves were consistent with the prevailing eastward winds in the mesosphere and the updraft associated with a low-pressure area that generally appears to the east of Resolute Bay at tropospheric altitudes. These results suggest that the main source of the gravity waves in the polar cap mesosphere is tropospheric dynamics rather than auroral activities. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013652

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Effects observed in the ionospheric <i>F</i> region in the east Asian sector during the intense geomagnetic disturbances in the early part of November 2004 査読有り Open Access

Sahai, Y; Becker-Guedes, F; Fagundes, PR; de Jesus, R; de Abreu, AJ; Otsuka, Y; Shiokawa, K; Igarashi, K; Yumoto, K; Huang, CS; Lan, HT; Saito, A; Guarnieri, FL; Pillat, VG; Bittencourt, JA

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 114 巻 ( 3 ) 2009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: Space Physics

The Sun was very active in the early part of November 2004. During the period of 8-10 November 2004, intense geomagnetic disturbances with two superstorms were observed. In a companion paper (hereinafter referred to as paper 1), the effects observed in the F region during the intense geomagnetic disturbances in the early part of November 2004 in the Latin American sector were presented. In the present paper, we investigate the effects observed in the F region during the intense geomagnetic disturbances in the early part of November 2004 in the east Asian sector. We have used the ionospheric sounding observations at Ho Chi Minh City (Vietnam) and Okinawa, Yamagawa, Kokubunji, and Wakkanai (Japan) in the present investigations. Also, GPS observations in the east Asian sector (several longitude zones) have been used to study the effect in the F region during the intense geomagnetic disturbances. The ion density versus latitudinal variations obtained by the DMSP F15 satellite orbiting at about 800 km altitude in the east Asian sector and the magnetic field data obtained at several stations in the Japanese meridian are also presented. Several important features from these observations in both the sectors during this extended period of intense geomagnetic disturbances are presented. The east Asian sector showed very pronounced effects during the second superstorm, which was preceded by two storm enhancements. It should be mentioned that around the beginning of the night on 10 November, ionospheric irregularities propagating from higher midlatitude region to low-latitude region were observed in the Japanese sector. The most intense geomagnetic field H component in that sector was observed on 10 November at L = 2.8, indicating that the auroral oval and the heating got further to low latitudes and the ionospheric irregularities observed in the Japanese sector on this night are midlatitude ionospheric disturbances associated with the second superstorm. The absence of ionospheric irregularities in the Japanese sector during the 8 November superstorm suggests that the magnetosphere-ionosphere system was possibly preconditioned (primed) when the second interplanetary structure impacted the magnetosphere. Copyright 2009 by the American Geophysical Union.

DOI： 10.1029/2008JA013053

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Equatorial GPS ionospheric scintillations over Kototabang, Indonesia and their relation to atmospheric waves from below 査読有り

Ogawa Tadahiko, Miyoshi Yasunobu, Otsuka Yuichi, Nakamura Takuji, Shiokawa Kazuo

EARTH PLANETS AND SPACE 61 巻 ( 4 ) 頁： 397 - 410 2009年

Fine structures and dynamics in auroral initial brightening at substorm onsets 査読有り

Sakaguchi K., Shiokawa K., Ieda A., Nomura R., Nakajima A., Greffen M., Donovan E., Mann I. R., Kim H., Lessard M.

ANNALES GEOPHYSICAE 27 巻 ( 2 ) 頁： 623-630 2009年

Propagation characteristics of nighttime mesospheric and thermospheric waves observed by optical mesosphere thermosphere imagers at middle and low latitudes 査読有り

Shiokawa K., Otsuka Y., Ogawa T.

EARTH PLANETS AND SPACE 61 巻 ( 4 ) 頁： 479-491 2009年

28pSP-16 イオンサイクロトロン波動による地球放射線帯電子の散乱(28pSP プラズマ宇宙物理(粒子加速,加熱,相対論プラズマ),領域2(プラズマ基礎・プラズマ科学・核融合プラズマ・プラズマ宇宙物理)) 査読有り

三好由純, 坂口歌織, 塩川和夫

日本物理学会講演概要集 64.1.2 巻 ( 0 ) 頁： 228 2009年

Characteristics of equatorial gravity waves derived from mesospheric airglow imaging observations 査読有り

Suzuki S., Shiokawa K., Liu A. Z., Otsuka Y., Ogawa T., Nakamura T.

ANNALES GEOPHYSICAE 27 巻 ( 4 ) 頁： 1625 - 1629 2009年

New observational deployments for SEALION-Airglow measurements using all-sky imagers 査読有り Open Access

Kubota M., Ishii M., Tsugawa T., Uemoto J., Jin H., Otsuka Y., Shiokawa K.

Journal of the National Institute of Information and Communications Technology 56 巻 ( 1-4 ) 頁： 299 - 307 2009年

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 the National Institute of Information and Communications Technology

An airglow all-sky imager (ASI)-a new monitoring instrument-is scheduled to be set up in February 2010 at Chiang Mai, Thailand, as part of the framework of the Southeast Asia Low-latitude Ionospheric Network (SEALION) being developed in the Southeast Asian region by the National Institute of Information and Communications Technology (NICT). The ASI images airglow having an emission layer near the ionospheric F-layer in order to observe the two-dimensional structure and time evolution of such ionospheric disturbances as plasma bubbles. In Southeast Asia, the Solar-Terrestrial Environment Laboratory (STE) of Nagoya University has been conducting ASI-based observations at Kototabang, Indonesia, ever since 2002. This paper provides detailed insight into the formation, growth and propagation of plasma bubbles as derived from observational data recorded using ASI at Kototabang and using SEALION ionoson-des and GPS receivers. The functional requirements for another ASI to be installed and ASI-based observation schemes are then discussed based on that insight.

Open Access

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Joint observations of a traveling ionospheric disturbance with the Paratunka OMTI camera and the Hokkaido HF radar 査読有り

Koustov A., Nishitani N., Ponomarenko P. V., Shiokawa K., Suzuki S., Shevtsov B. M., MacDougall J. W.

ANNALES GEOPHYSICAE 27 巻 ( 6 ) 頁： 2399 - 2406 2009年

Effects of geomagnetically induced current on power grids 査読有り

Watari S, Kunitake M, Kitamura K, Hori T, Kikuchi T, Shiokawa K, Nishitani N, Kataoka R, Kamide Y, Watanabe Y

Journal of the National Institute of Information and Communications Technology 56 巻 ( 1-4 ) 頁： 125 - 133 2009年

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 the National Institute of Information and Communications Technology

There have been many reports that geomagnetically induced current (GIC) has affected the operation of electric power grids. Given Japan's location at lower geomagnetic latitude than its geographic latitude, the effects of GIC on electric power grids there are believed to be small, but have yet to be subjected to elaborate analysis. This paper describes the results of GIC measured in Hokkaido over a two-year period in collaboration with the National Institute of Information and Communications Technology (NICT), Hokkaido Electric Power Co., Inc., and the Solar- Terrestrial Environment Laboratory (STEL) of Nagoya University.

Scopus

その他リンク： http://orcid.org/0000-0001-8451-6941

ULF geomagnetic anomalous changes possibly associated with 2004-2005 Sumatra earthquakes 査読有り

Saroso S., Hattori K., Ishikawa H., Ida Y., Shirogane R., Hayakawa M., Yumoto K., Shiokawa K., Nishihashi M.

PHYSICS AND CHEMISTRY OF THE EARTH 34 巻 ( 6-7 ) 頁： 343 - 349 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics and Chemistry of the Earth

Anomalous ULF geomagnetic field change is considered to be one of the most convincing and promising phenomena among earthquake-related electromagnetic effects, because we expect emissions from the crust of the source region. There has been a great deal of accumulated and convincing evidence of ULF magnetic signatures before large earthquakes as reported in the previous studies. In order to verify these phenomena preceding large earthquakes and to clarify the relationship between electromagnetic phenomena and possible physical mechanism, we have investigated the data of ULF geomagnetic observations at Kototabang and Biak stations associated with the 2004/2005 Sumatra earthquakes. A case study is carried out in this work to investigate the pre-earthquake ULF geomagnetic anomalies during the Sumatra-Andaman earthquake on December 26, 2004 (magnitude Mw = 9.0 and depth = 30 km from USGS catalog), and Sumatra-Nias earthquake on March 28, 2005 (Mw = 8.7 and depth = 30 km). For the aim of finding any precursors, we have adopted the spectral density ratio analysis and transfer functions analysis based on wavelet transform method. Results of the spectral density analysis indicate similar variations to those of amplitude for the induction arrow in transfer function analysis. Both of these variations at Kototabang exhibit strange or anomalous changes from a few weeks before the Sumatra-Andaman earthquake to July 2005, while there are no apparent changes at remote station of Biak. To make these results more convincing, the fractal analysis based on a Higuchi method has been applied to the same observed data, which also show a significant change (or decrease) in mono-fractal dimension a few weeks before the earthquakes. This result would lend a further support to those by the spectral density ratio and transfer function analyses. So, we can conclude that the anomalous change as observed simultaneously by the three methods, might be a possible signature related with the earthquake preparation phase of Sumatra earthquakes. © 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.pce.2008.10.065

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Longitudinal development of a substorm brightening arc 査読有り

Shiokawa K., Ieda A., Nakajima A., Sakaguchi K., Nomura R., Aslaksen T., Greffen M., Spanswick E., Donovan E., Mende S. B., McFadden J., Glassmeier K. -H., Angelopoulos V., Miyashita Y.

ANNALES GEOPHYSICAE 27 巻 ( 5 ) 頁： 1935 - 1940 2009年

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