研究者詳細 - 藤木　謙一

論文 - 藤木　謙一

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A Study of an Equatorial Coronal Hole Observed at the First Parker Solar Probe Perihelion 査読有り

Karna Nishu, Berger Mitchell A., Asgari-Targhi Mahboubeh, Paulson Kristoff, Fujiki Ken'ichi

ASTROPHYSICAL JOURNAL 925 巻 ( 1 ) 2022年1月

Global Distribution of the Solar Wind Speed Reconstructed from Improved Tomographic Analysis of Interplanetary Scintillation Observations between 1985 and 2019 査読有り

Tokumaru Munetoshi, Fujiki Ken'ichi, Kojima Masayoshi, Iwai Kazumasa

ASTROPHYSICAL JOURNAL 922 巻 ( 1 ) 2021年11月

Coordinated Interplanetary Scintillation Observations in Japan and Russia for Coronal Mass Ejection Events in Early September 2017 査読有り

Tokumaru Munetoshi, Fujiki Ken'ichi, Iwai Kazumasa, Tyul'bashev Sergey, Chashei Igor

SOLAR PHYSICS 294 巻 ( 7 ) 2019年7月

Development of a coronal mass ejection arrival time forecasting system using interplanetary scintillation observations 査読有り

Iwai Kazumasa, Shiota Daikou, Tokumaru Munetoshi, Fujiki Ken'ichi, Den Mitsue, Kubo Yuki

EARTH PLANETS AND SPACE 71 巻 2019年4月

High-latitude Conic Current Sheets in the Solar Wind 査読有り

Khabarova Olga V., Malova Helmi V., Kislov Roman A., Zelenyi Lev M., Obridko Vladimir N., Kharshiladze Alexander F., Tokumaru Munetoshi, Sokol Justyna M., Grzedzielski Stan, Fujiki Ken'ichi

ASTROPHYSICAL JOURNAL 836 巻 ( 1 ) 2017年2月

Magnetohydrodynamic simulation of coronal mass ejections using interplanetary scintillation data observed from radio sites ISEE and LOFAR 査読有り国際共著

Iwai, Kazumasa ; Fallows, Richard A. ; Bisi, Mario M. ; Shiota, Daikou ; Jackson, Bernard V. ; Tokumaru, Munetoshi ; Fujiki, Ken'ichi

Advances in Space Research 72 巻 ( 12 ) 2023年12月

Interplanetary scintillation (IPS) analyses during LOFAR campaign mode periods that include the first three Parker Solar Probe close passes of the Sun 査読有り

Jackson, B. V. ; Tokumaru, M. ; Fallows, R. A. ; Bisi, M. M. ; Fujiki, K. ; Chashei, I. ; Tyul'bashev, S. ; Chang, O. ; Barnes, D. ; Buffington, A. ; Cota, L. ; Bracamontes, M.

Advances in Space Research 72 巻 ( 12 ) 2023年12月

East-West Asymmetry in Interplanetary-Scintillation-Level Variation Associated with Solar-Wind Disturbances 招待有り査読有り

Tokumaru, Munetoshi ; Nagai, Miho ; Fujiki, Ken'ichi ; Iwai, Kazumasa

Solar Physics 298 巻 ( 11 ) 2023年11月

The Origin of Extremely Nonradial Solar Wind Outflows 招待有り査読有り国際共著

Rout, Diptiranjan ; Janardhan, P. ; Fujiki, K. ; Chakrabarty, D. ; S. K., Bisoi

The Astrophysical Journal 950 巻 ( 1 ) 2023年6月

Forecasting Heliospheric CME Solar-Wind Parameters Using the UCSD Time-Dependent Tomography and ISEE Interplanetary Scintillation Data: The 10 March 2022 CME 招待有り査読有り国際共著

Jackson, Bernard V. ; Tokumaru, Munetoshi ; Iwai, Kazumasa ; Bracamontes, Matthew T. ; Buffington, Andrew ; Fujiki, Ken'ichi ; Murakami, Go ; Heyner, Daniel ; Sanchez-Cano, Beatriz ; Rojo, Mathias ; Aizawa, Sae ; Andre, Nicolas ; Barthe, Alain ; Penou, Emmanuel ; Fedorov, Andrei ; Sauvaud, Jean-Andre ; Yokota, Shoichiro ; Saito, Yoshifumi

Solar Physics 298 巻 ( 5 ) 2023年5月

Interplanetary Scintillation Observations of Solar-Wind Disturbances During Cycles 23 and 24 招待有り査読有り

Tokumaru, Munetoshi; Fujiki, Ken'ichi; Iwai, Kazumasa

Solar Physics 298 巻 ( 2 ) 2023年2月

Validation of coronal mass ejection arrival-time forecasts by magnetohydrodynamic simulations based on interplanetary scintillation observations 査読有り

Iwai Kazumasa, Shiota Daikou, Tokumaru Munetoshi, Fujiki Ken'ichi, Den Mitsue, Kubo Yuki

EARTH PLANETS AND SPACE 73 巻 ( 1 ) 2021年1月

A Daily Determination of B-Z Using the Russell-McPherron Effect to Forecast Geomagnetic Activity 査読有り

Jackson B. V, Yu H-S, Buffington A., Hicks P. P., Tokumaru M., Fujiki K., Kim J., Yun J.

SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS 17 巻 ( 4 ) 頁： 639 - 652 2019年4月

Comparative Study of Microwave Polar Brightening, Coronal Holes, and SolarWind over the Solar Poles 査読有り

Ken'ichi Fujiki, Kiyoto Shibasaki, Seiji Yashiro, Munetoshi Tokumaru, Kazumasa Iwai, Satoshi Masuda

Solar Physics 2019年3月

Comparative Study of Microwave Polar Brightening, Coronal Holes, and Solar Wind over the Solar Poles 査読有り

Fujiki Ken'ichi, Shibasaki Kiyoto, Yashiro Seiji, Tokumaru Munetoshi, Iwai Kazumasa, Masuda Satoshi

SOLAR PHYSICS 294 巻 ( 3 ) 2019年3月

Solar cycle 24: An unusual polar field reversal 査読有り

Janardhan, P, Fujiki, K, Ingale, M, Bisoi, S.~K, Rout, D

Astronomy and Astrophysics 618 巻 2018年8月

Rarefaction of the Very Slow (< 350 km/s) Solar Wind in Cycle 24 Compared With Cycle 23

Tokumaru Munetoshi, Shimoyama Tomoya, Fujiki Ken'ichi, Hakamada Kazuyuki

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 123 巻 ( 4 ) 頁： 2520 - 2534 2018年4月

Relation Between Coronal Hole Areas and Solar Wind Speeds Derived from Interplanetary Scintillation Measurements

Tokumaru Munetoshi, Satonaka Daiki, Fujiki Ken'ichi, Hayashi Keiji, Hakamada Kazuyuki

SOLAR PHYSICS 292 巻 ( 3 ) 2017年3月

LONG-TERM TREND OF SOLAR CORONAL HOLE DISTRIBUTION FROM 1975 TO 2014 査読有り

K. Fujiki, M. Tokumaru, K. Hayashi, D. Satonaka, K. Hakamada

Astrophysical Journal Letter 827 巻頁： 41-45 2016年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

We developed an automated prediction technique for coronal holes using potential magnetic field extrapolation in the solar corona to construct a database of coronal holes appearing from 1975 February to 2015 July (Carrington rotations from 1625 to 2165). Coronal holes are labeled with the location, size, and average magnetic field of each coronal hole on the photosphere and source surface. As a result, we identified 3335 coronal holes and found that the long-term distribution of coronal holes shows a similar pattern known as the magnetic butterfly diagram, and polar/low-latitude coronal holes tend to decrease/increase in the last solar minimum relative to the previous two minima.

A Prolonged Southward IMF-Bz Event of May 02-04, 1998: Solar, Interplanetary Causes and Geomagnetic Consequences 査読有り

Bisoi, Susanta Kumar, Chakrabarty, D., Janardhan, P., Rastogi, R. G., Yoshikawa, A., Fujiki, K., Tokumaru, M., Yan, Y.

Journal of Geophisical Research (space) 頁： in press 2016年

Relationship Between Solar-Wind Speed and Coronal Magnetic-Field Properties 査読有り

K. Fujiki, M. Tokumaru, T. Iju, K. Hakamada, M. Kojima

Solar Physics 290 巻頁： 2491-2505 2015年9月

A 20 year decline in solar photospheric magnetic fields: Inner-heliospheric signatures and possible implications

Janardhan, P., Bisoi, Susanta Kumar, Ananthakrishnan, S., Tokumaru, M., Fujiki, K., Jose, L., Sridharan, R.

Journal of Geophysical Research: Space Physics 120 巻 ( 7 ) 頁： 5306-5317 2015年7月

North-south asymmetry in global distribution of the solar wind speed during 1985-2013

Tokumaru, Munetoshi; Fujiki, Ken'ichi; Iju, Tomoya

Journal of Geophysical Research: Space Physics 120 巻 ( 5 ) 頁： 3283-3296 2015年5月

A Study of Density Modulation Index in the Inner Heliospheric Solar Wind during Solar Cycle 23 査読有り

Bisoi, S.K.; Janardhan, P.; Ingale, M.; Subramanian, P.; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.

Astrophysical Journal 795 巻頁： 69 2014年11月

Kinematic Properties of Slow ICMEs and an Interpretation of a Modified Drag Equation for Fast and Moderate ICMEs 査読有り

Iju, T.; Tokumaru, M.; Fujiki, K.

Solar Physics 289 巻頁： 2157-2175 2014年6月

MHD analysis of the velocity oscillations in the outer heliosphere 査読有り

Fujiki, K. ; Washimi, H.; Hayashi, K.; Zank, G.P.; Tokumaru, M.; Tanaka, T.; Florinski, V.; Kubo, Y.

Geophysical Research Letter 41 巻頁： 1420-1424 2014年3月

Radial Speed Evolution of Interplanetary Coronal Mass Ejections During Solar Cycle 23 査読有り

Iju, T.; Tokumaru, M.; Fujiki, K.

Solar Physics 288 巻 ( 1 ) 頁： 331-353 2013年11月

Heliolatitude and Time Variations of Solar Wind Structure from in situ Measurements and Interplanetary Scintillation Observations 査読有り

Sokół, J. M.; Bzowski, M.; Tokumaru, M.; Fujiki, K.; McComas, D. J.

Solar Physics 285 巻 ( 1-2 ) 頁： 167-200 2013年7月

Kinematics of interplanetary coronal mass ejections in the inner heliosphere 査読有り

Iju, Tomoya; Tokumaru, Munetoshi; Fujiki, Ken'ichi

SOLAR WIND 13: Proceedings of the Thirteenth International Solar Wind Conference. AIP Conference Proceedings 1539 巻頁： 183-186 2013年6月

Evolution of global distribution of the solar wind from cycle 23 to the early phase of cycle 24 査読有り

Tokumaru, Munetoshi; Fujiki, Ken'ichi; Kojima, Masayoshi

SOLAR WIND 13: Proceedings of the Thirteenth International Solar Wind Conference. AIP Conference Proceedings 1539 巻頁： 275-278 2013年6月

Scintillation Measurements of the Solar Wind Velocity in Strong Scattering near the Sun

M. Kojima, W. A. Coles, M. Tokumaru, K. Fujiki

Solar Physics 283 巻 ( 2 ) 頁： 519-540 2013年1月

The First Three Years of IBEX Observations and Our Evolving Heliosphere 査読有り

D. J. McComas, M. A. Dayeh, F. Allegrini, M. Bzowski, R. DeMajistre, K. Fujiki, H. O. Funsten, S. A. Fuselier, M. Gruntman, P. H. Janzen, M. A. Kubiak, H. Kucharek, G. Livadiotis, E. Möbius, D. B. Reisenfeld, M. Reno, N. A. Schwadron, J. M. Sokół, and M. Tokumaru

The Astrophysical Journal Supplement Series 203 巻 ( 1 ) 2012年10月

Global Observations of Evolving 3D Solar Wind Structure 査読有り

Tokumaru, M.; Fujiki, K.; Itoh, H.; Iju, T.; Kojima, M.

Hinode-3: The 3rd Hinode Science Meeting, Proceedings of the conference held 1-4 December 2009 at Hitotsubashi Memorial Hall, Tokyo, Japan. Edited by T. Sekii, T. Watanabe, and T. Sakurai. ASP Conference Series 454 巻頁： 413 2012年8月

Long-term evolution in the global distribution of solar wind speed and density fluctuations during 1997-2009 査読有り

Tokumaru, Munetoshi; Kojima, Masayoshi; Fujiki, Ken'ichi

Journal of Geophysical Research 117 巻 ( A6 ) 2012年6月

Heliolatitude and Time Variations of Solar Wind Structure from in situ Measurements and Interplanetary Scintillation Observations 査読有り

Sokół, J. M.; Bzowski, M.; Tokumaru, M.; Fujiki, K.; McComas, D. J.

Solar Physics 2012年5月

Solar wind evolution since 1990 and H ENA ionization rates and survival probabilities in the heliosphere 査読有り

Sokol, J. M.; Kubiak, M. A.; Bzowski, M.; Tokumaru, M.; Fujiki, K.; McComas, D. J.; Bochsler, P.

EGU General Assembly 2012, held 22-27 April, 2012 in Vienna, Austria 頁： 4723 2012年4月

Two-Station Interplanetary Scintillation Measurements of Solar Wind Speed near the Sun Using the X-band Radio Signal of the Nozomi Spacecraft 査読有り

Tokumaru, M.; Fujimaki, S.; Higashiyama, M.; Yokobe, A.; Ohmi, T.; Fujiki, K.; Kojima, M.

Solar Physics 276 巻頁： 315-336 2012年2月

Solar parameters for modeling interplanetary background 査読有り

Bzowski, M.; Sokol, J. M.; Tokumaru, M.; Fujiki, K.; Quemerais, E.; Lallement, R.; Ferron, S.; Bochsler, P.; McComas, D. J.

ISSI Scientific Report No 12 12 巻 2011年12月

Three-Dimensional Solar Wind Structures Obtained with MHD Simulation Model Using Observation-Based Time-Varying Inner Boundary Map 査読有り

Hayashi, K.; Tokumaru, M.; Fujiki, K.; Kojima, M.

5th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2010) 444 巻頁： 111 2011年10月

The prelude to the deep minimum between solar cycles 23 and 24: Interplanetary scintillation signatures in the inner heliosphere 査読有り

Janardhan, P.; Bisoi, Susanta Kumar; Ananthakrishnan, S.; Tokumaru, M.; Fujiki, K.

GEOPHYSICAL RESEARCH LETTERS 38 巻 2011年10月

Two-Station Interplanetary Scintillation Measurements of Solar Wind Speed near the Sun Using the X-band Radio Signal of the Nozomi Spacecraft 査読有り

M. Tokumaru, S. Fujimaki, M. Higashiyama, A. Yokobe, T. Ohmi, K. Fujiki and M. Kojima

SOLAR PHYSICS 2011年8月

Solar Mass Ejection Imager (SMEI) 3-D reconstruction of density enhancements behind interplanetary shocks: In-situ comparison near Earth and at STEREO 査読有り

Jackson, B. V.; Hamilton, M. S.; Hick, P. P.; Buffington, A.; Bisi, M. M.; Clover, J. M.; Tokumaru, M.; Fujiki, K.

Journal of Atmospheric and Solar-Terrestrial Physics 73 巻 ( 11-12 ) 頁： 1317-1329 2011年7月

Three-dimensional reconstruction of heliospheric structure using iterative tomography: A review 査読有り

Jackson, B. V.; Hick, P. P.; Buffington, A.; Bisi, M. M.; Clover, J. M.; Tokumaru, M.; Kojima, M.; Fujiki, K.

Journal of Atmospheric and Solar-Terrestrial Physics 73 巻 ( 10 ) 頁： 1214-1227 2011年6月

Three-dimensional Reconstructions and Mass Determination of the 2008 June 2 LASCO Coronal Mass Ejection Using STELab Interplanetary Scintillation Observations 査読有り

Bisi, M. M.; Jackson, B. V.; Hick, P. P.; Buffington, A.; Clover, J. M.; Tokumaru, M.; Fujiki, K.

The Astrophysical Journal Letters 715 巻 ( 2 ) 頁： L104-L108 2010年6月

Solar cycle evolution of the solar wind speed distribution from 1985 to 2008 査読有り

Tokumaru, Munetoshi; Kojima, Masayoshi; Fujiki, Ken'ichi

Journal of Geophysical Research 115 巻 ( A4 ) 頁： CiteID A04102 2010年4月

Solar Wind Forecast by Using Interplanetary Scintillation Observations 査読有り

Fujiki, K., Ito, H, Tokumaru, M.

TWELFTH INTERNATIONAL SOLAR WIND CONFERENCE. AIP Conference Proceedings 1216 巻頁： 663-666 2010年3月

Is the Polar Region Different from the Quiet Region of the Sun? 査読有り

Ito, Hiroaki; Tsuneta, Saku; Shiota, Daikou; Tokumaru, Munetoshi; Fujiki, Ken'ichi

TWELFTH INTERNATIONAL SOLAR WIND CONFERENCE. AIP Conference Proceedings 1216 巻頁： 88-89 2010年3月

Large-Scale Heliospheric Structure during Solar-Minimum Conditions using a 3D Time-Dependent Reconstruction Solar-Wind Model and STELab IPS Observations 査読有り

Bisi, M. M.; Jackson, B. V.; Hick, P. P.; Clover, J. M.; Hamilton, S.; Tokumaru, M.; Fujiki, K.

TWELFTH INTERNATIONAL SOLAR WIND CONFERENCE. AIP Conference Proceedings 1216 巻頁： 355-358 2010年3月

3D Reconstruction of Density Enhancements Behind Interplanetary Shocks from Solar Mass Ejection Imager White-Light Observations 査読有り

Jackson, B. V.; Hick, P. P.; Buffington, A.; Bisi, M. M.; Clover, J. M.; Hamilton, M. S.; Tokumaru, M.; Fujiki, K.

TWELFTH INTERNATIONAL SOLAR WIND CONFERENCE. AIP Conference Proceedings 1216 巻頁： 659-662 2010年3月

Evolution of the anemone AR NOAA 10798 and the related geo-effective flares and CMEs 査読有り

Asai, Ayumi; Shibata, Kazunari; Ishii, Takako T.; Oka, Mitsuo; Kataoka, Ryuho; Fujiki, Ken'ichi; Gopalswamy, Nat

Journal of Geophysical Research 114 巻 ( A12 ) 頁： CiteID A00A21 2010年2月

Is the Polar Region Different from the Quiet Region of the Sun? 査読有り

Ito, Hiroaki; Tsuneta, Saku; Shiota, Daikou; Tokumaru, Munetoshi; Fujiki, Ken'ichi

The Astrophysical Journal 719 巻 ( 1 ) 頁： 131-142 2010年

From the Sun to the Earth: The 13 May 2005 Coronal Mass Ejection 査読有り

Bisi, M. M.; Breen, A. R.; Jackson, B. V.; Fallows, R. A.; Walsh, A. P.; Mikić, Z.; Riley, P.; Owen, C. J.; Gonzalez-Esparza, A.; Aguilar-Rodriguez, E.; Morgan, H.; Jensen, E. A.; Wood, A. G.; Owens, M. J.; Tokumaru, M.; Manoharan, P. K.; Chashei, I. V.; Giunta, A. S.; Linker, J. A.; Shishov, V. I.; Tyul'Bashev, S. A.; Agalya, G.; Glubokova, S. K.; Hamilton, M. S.; Fujiki, K.; Hick, P. P.; Clover, J. M.; Pintér, B.

Solar Physics 265 巻 ( 1-2 ) 頁： 49-127 2010年

Relation between loop-shaped interplanetary disturbances and the magnetic flux rope 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, K. Munakata, T. Kuwabara, and K. Marubashi

Advances in Geoscience (World Scientific Publishing Co., USA) 3 巻頁： in press 2009年

Non-dipolar solar wind structure observed in the cycle 23/24 minimum 査読有り

Tokumaru, M., Kojima, M., Fujiki, K., Hayashi, K.

Geophysical Research Letters 36 巻 ( p ) 頁： CiteID L09101 2009年

Interplanetary scintillation observations of the solar wind for space weather modeling 査読有り

Tokumaru, M., M. Kojima, and K. Fujiki

Space Technology Japan 8 巻頁： in press 2009年

Origins and properties of the quasi-stationary slow solar wind 査読有り

Eselevich, M. V., Eselevich, V. G., Fujiki, K.

Astronomy Reports 52 巻 ( 7 ) 頁： 576-589 2008年

A solar neutron telescope in Tibet and its capability examined by the 1998 November 28th event 査読有り

Y. Murakia, H. Tsuchiya, K. Fujiki, S. Masuda, Y. Matsubara, H. Menjyo, T. Sako, K. Watanabe, M. Ohnishi, A. Shiomi, M. Takita, T. Yuda, Y. Katayose, N. Hotta, S. Ozawa, T. Sakurai, Y.H. Tan and J.L. Zhang

Astroparticle Physics 28 巻 ( 1 ) 頁： 119-131 2007年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

A new solar neutron telescope has been constructed at Yangbajing, Tibet (600 g/cm2) and has been successfully operated for 8 years. During this time several interesting events were observed in coincidence with large solar flares. In this paper the authors discuss a directional count rate enhancement 1998 November 28 as to whether it is related to solar phenomena or not. We use this event to evaluate the sensitivity of the solar neutron telescope and discuss the detection limit for solar neutrons and high energy solar protons of this detector.

*What coronal parameters determine solar wind speed? 査読有り

Kojima, M., M. Tokumaru, K. Fujiki, H. Itoh, T. Murakami, and K. Hakamada

New Solar Physics with Solar-B Mission", ASP Conference Series,eds K. Shibata, S. Nagata, and T. Sakurai 369 巻頁： 549-555 2007年

記述言語：英語

It is crucially important for modeling solar wind acceleration to find universal physical parameters which can determine velocities of all kinds of solar wind from various sources such as slow wind from a helmet streamer, slow wind from an equatorial small coronal hole, the fast wind from a polar coronal hole. One of the parameters is the coronal hole scale size. A large-scale polar coronal hole is a source of fast solar wind, and medium and slow speed streams originate in smaller coronal holes. Nolte et al. (1976) obtained a linear correlation between the solar wind speed and coronal hole scale size for equatorial coronal holes. Kojima et al. (2004) analyzed the dependence of the solar wind speed on the scale size of high latitude coronal holes and reported that the speed was independent of the scale size if it was larger than 5X1010 km2. Another property is a flux expansion rate (f), which has a good inverse relation with solar wind velocity (Wang and Sheeley, 1990), and the third parameter is the magnetic field (B) energy released by reconnection at the lower corona (Fisk et al., 1999).
We have studied physical conditions of coronal magnetic field which determine solar wind velocity using an interplanetary scintillation method which can observe the solar wind at all latitudinal ranges. From studies in the solar minimum phase we found that the ratio of two parameters of B and f has a considerably higher correlation with the solar wind velocity than an individual parameter of f and B. This work gives the crucially important constraints for the solar wind acceleration models.

IPS tomographic observations of 3D solar wind structure 査読有り

Kojima, M., M. Tokumaru, K. Fujiki, K. Hayashi, and B. V. Jackson

Astronomical and Astrophysical Transactions 26 巻頁： 467-476 2007年

The source and propagation of the interplanetary disturbance associated with the full-halo coronal mass ejection on 28 October 2003 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, M. Yamashita, and B. V. Jackson

(10.1029/ 2006JA012043) 巻 2007年

Streamer belt and chains as the main sources of quasi-stationary slow solar wind 査読有り

Eselevich, M., V. Eselevich, and K. Fujiki

Solar Physics 240 巻 ( 135-151 ) 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

It has been known that periods of the low geomagnetic activity in near-earth environment coincide with arrival time of the “slow" solar wind (SW) at Earth's orbit. In this connection, sources of the “slow" SW on the Sun are significant issue in the space weather problem. In this work synoptic maps of white-light coronal brightness from SOHO/LASCO C2 and distributions of solar wind velocity obtained from interplanetary scintillation were studied. Regions with velocity V ≈ 300-450 km s-1 and increased density N > 10 cm-3, typical of the “slow" solar wind originating from the belt and chains of streamers, are shown to exist at Earth's orbit, between the fast solar wind flows (with a maximum velocity Vmax ≈ 450-800 km s-1). The belt and chains of streamers are the main sources of the “slow" solar wind. As the sources of “slow" solar wind, the contribution from the chains of streamers may be comparable to that from the streamer belt.

Tracking heliospheric disturbances by interplanetary scintillation 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, and M. Yamashita

Nonlin. Processes Geophys. 13 巻頁： 329-338 2006年

Reconstructed global feature of interplanetary disturbance for the full-halo coronal mass ejection event on 1999 September 20 査読有り

Tokumaru, M., M. Yamashita, M. Kojima, K. Fujiki, and T. Nakagawa

Adv. Space Res. 38 巻頁： 547-551 2006年

Interplanetary consequences caused by the extremely intense solar activity during October-November 2003 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, M. Yamashita

J. Geophys. Res. in press 巻頁： doi:10.1029/2004JA010656 2005年

*Relation between solar wind velocity and properties of its source region 招待有り査読有り

Fujiki, K., M. Hirano, M. Kojima, M. Tokumaru, D. Baba, M., Yamashita, K. Hakamada

Advances in Space Research 2005 巻頁： doi:10.1016/i.asr.2005.05.057 2005年

担当区分：筆頭著者記述言語：英語

Different kinds of coronal holes are sources of different kind of solar winds. A successful solar wind acceleration model should be able to explain all those solar winds. For the modeling it is important to find a universal relation between the solar wind physical parameters, such as velocity, and coronal physical parameters such as magnetic field energy. To clarify the physical parameters which control the solar wind velocity, we have studied the relation between solar wind velocity and properties of its source region such as photospheric/coronal magnetic field and the size of each coronal hole during the solar minimum. The solar wind velocity structures were derived by using interplanetary scintillation tomography obtained at Solar-Terrestrial Environment Laboratory, Japan. Potential magnetic fields were calculated to identify the source region of the solar wind. HeI 1083 nm absorption line maps obtained at Kitt Peak National Solar Observatory were used to identify coronal holes. As a result, we found a relation during solar minimum between the solar wind velocity and the coronal magnetic condition which is applicable to different kind of solar winds from different kind of coronal holes.

Resolving the enigmatic solar wind disappearance event of 11 May 1999 査読有り

Janardhan, P., K. Fujiki, M. Kojima, M. Tokumaru, and K. Hakamada

Journal of Geophysical Research 110 巻頁： 10.1029/2005JA010535 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

On 11 and 12 May 1999, the Earth was engulfed by an unusually low-density (<1 cm^-3) and low-velocity (<350 km s^-1) solar wind for a period of over 1 day. Extensive studies of this unusual event that occurred during Carrington rotation 1949 (CR1949), using both ground-based and space-based in situ observations, have not as yet been able to identify the cause or the solar source of this event. Using solar wind velocity measurements from the four-station IPS observatory of the Solar-Terrestrial Environment Laboratory (STEL), Toyokawa, Japan, we investigate the structure of the solarwind in May 1999 during CR1949. IPS observations from STEL were used to make tomographic velocity maps to identify and delineate the extent and morphology of the stable solar wind flows during CR1949 in the vicinity of the Earth. Combined with in situ measurements of the interplanetary magnetic field (IMF), potential field computations of the solar magnetic fields in the period, and HeI 10830A° observations of coronal hole boundaries during CR1949, we have identified the source region of the unusual flows and have shown that the flow responsible for the "disappearance event" was a stable unipolar flow originating in the vicinity of a large midlatitude active region AR8525, located at 18N and between heliographic longitudes 280 and 300. Earlier workers have speculated that such events may be caused by the large-scale restructuring of the solar magnetic field at the maximum of each solar cycle. However, by identifying the solar source and nature of this event, we believe that at least in this particular case, the association with global, large-scale solar phenomena like the periodic 11-year solar polar field reversal is most likely to be coincidental.

Correlation between expansion rate of the coronal magnetic field and solar wind speed in a solar activity cycle 査読有り

Hakamada, K., M. Kojima, T. Ohmi, M. Tokumaru, K. Fujiki

Solar Physics 227 巻頁： 387-399 2005年

Origin of the slow solar wind 査読有り

Ohmi, T., M. Kojima, M. Tokumaru, K. Fujiki, and K. Hakamada

Adv. Space Res. 33 巻頁： 689-695 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

The origin of the slow solar wind is an interesting subject on its own, and is also important in relation to the origin of the solar wind including the fast solar wind, especially if the slow wind originates directly from a coronal hole. We have been studying the solar wind whose speed is comparable to, or slower than, that measured in the heliospheric plasma sheet. We derived solar wind velocity distribution maps on the source surface using an interplanetary scintillation tomography analysis, and low-speed regions in them were investigated in relation to a coronal hole using potential field magnetic field lines.
We found the slow solar wind which originated from an equatorial coronal hole located in the vicinity of active regions and also from a polar coronal hole which was about to disappear at the solar activity maximum. The properties of the slow solar wind from an equatorial coronal hole were investigated using spacecraft in situ measurements. Magnetic polarity in this wind was uniform, as expected from a potential field analysis. The helium relative abundance was as large as the fast wind, and variances of density, velocity, and helium abundance were as small as the fast wind from a large coronal hole. In spite of the small equatorial coronal hole origin, the density and ion freeze-in temperature were as large as observed for the slow wind in the heliospheric plasma sheet.
This study clearly showed one of the origins of the slow solar wind and solved the age-old puzzle as to why a potential neutral line does not tend to pass through the locus of a low-speed stream. We think this work provides crucial information to reveal what determines the acceleration efficiency of the solar wind: physical properties in the coronal base or/and flux expansion.

Fast solar wind after the rapid acceleration 査読有り

Kojima, M., A. R. Breen, K. Fujiki, K. Hayashi, T. Ohmi, and M. Tokumaru

J. Geophys. Res. 109 巻頁： (10.1029/2003JA010247) 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

Since Grall et al. (1996) reported the acceleration profile of the polar solar wind near the sun region, the acceleration of the polar wind has been thought to be rapid. However, their velocities measured with interplanetary scintillation (IPS) method have a large velocity spread with some measurements being over 1000 km/s. Coles and Harmon (2001) have shown that density fluctuations produced by oblique Alfve´n waves can cause a large overestimation of flow velocities in the IPS measurement especially within 20 Rs. They attributed the wide spread of radial velocities obtained in IPS measurements near the Sun to this biasing effect. Therefore, the acceleration profile of the fast solar wind, how it is accelerated and how it approaches asymptotically the final velocity, has not yet elucidated, and it is crucially important for the study of solar wind acceleration.
We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13–0.9 AU. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. For this study a new IPS tomographic analysis method was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU form IPS observations. From this analysis, average velocities of 770–780 km/s were obtained at distances of 0.13–0.3 AU, which were 19 ± 17 km/s lower than those at 0.3–0.9 AU. The results from this work, taken together with measurements of SOHO/LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 Rs and a small but not negligible acceleration exists beyond 30 Rs which tends to become smaller at farther heliocentric distances.
This work revealed that the so-called rapid acceleration does not mean the completion of the acceleration within 10 s

Solar cycle dependence of high-latitude solar wind 査読有り

Fujiki, K., M. Kojima, M. Tokumaru, T. Ohmi, A. Yokobe, and K. Hayashi

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 141-143 2003年

Radial dependence of propagation speed of solar wind disturbance 査読有り

Yamashita, M., M. Tokumaru, and M. Kojima

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 754-757 2003年

Global structure of interplanetary coronal mass ejections retrieved from the model fitting analysis of radio scintillation observations 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, and M. Yamashita

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 729-732 2003年

Toroidal-shape interplanetary disturbances associated with the halo coronal mass ejection event on July 14, 2000 査読有り

Tokumaru, M., M. Kojima, K. Fujiki, M. Yamashita, and A. Yokobe

J. Geophys. Res. 108 巻頁： 1220 2003年

Evidences for low-speed streams from small coronal hole 査読有り

Ohmi, T., M. Kojima, K. Hayashi, A. Yokobe, M. Tokumaru, K. Fujiki, and K. Hakamada

Solar Wind Ten, AIP Conference Proceeding 679 巻頁： 137-140 2003年

Polar low-speed solar wind reappeared at the solar activity maximum of cycle 23 査読有り

Ohmi, T., M. Kojima, M. Tokumaru, K. Fujiki, K. Hayashi, and K. Hakamada

Geophy. Res. Lett 30 巻頁： 1409-1412 2003年

Time-dependent tomography of heliospheric features using interplanetary scintillation (IPS) remote-sensing observations 査読有り

Jackson, B.V., P.P. Hick, A. Buffington, M. Kojima, M. Tokumaru, K. Fujiki, T. Ohmi, and M. Yamashita

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 75-78 2003年

MHD tomography using interplanetary scintillation measurement 査読有り

Hayashi, K., M. Kojima, M. Tokumaru, and K. Fujiki

Journal of Geophysical Research 108 巻頁： (10.1029/2002JA009567) 2003年

Basic results of MHD tomography analysis method for IPS observation 査読有り

Hayashi, K., K. Fujiki, M. Kojima, and M. Tokumaru

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 144-147 2003年

*How did the solar wind structure change around the solar maximum? - From interplanetary scintillation observation 査読有り

Fujiki, K., M. Kojima, M. Tokumaru, T. Ohmi, A. Yokobe, K. Hayashi, D. J. McComas, and H. A. Elliott

Annales Geophysicae 21 巻頁： 1257-1261 2003年

Solar wind velocity structure around the solar maximum observed by interplanetary scintillation 査読有り

Fujiki, K., M. Kojima, M. Tokumaru, T. Ohmi, A. Yokobe, K. Hayashi, D. J. McComas, and H. A. Elliott

Solar Wind Ten, AIP Conference Proceedings 679 巻頁： 226-229 2003年

Tomographic analysis of solar wind structure using interplanetary scintillation 査読有り

Kojima, M., K. Fujiki, M. Tokumaru, T. Ohmi, Y. Shimizu, A. Yokobe, B.V. Jackson, and P.L. Hick

COSPAR Colloquium Series 12 巻頁： 55-59 2002年

Solar wind speed and expansion rate of the coronal magnetic field in solar maximum and minimum phases 査読有り

Hakamada, K., M. Kojima, M. Tokumaru, T. Ohmi, A. Yokobe, and K. Fujiki

Solar Physics 207 巻頁： 173－185 2002年

Latitudinal velocity structures up to the solar poles estimated from IPS tomography analysis 査読有り

Kojima, M., K. Fujiki, T. Ohmi, M. Tokumaru, A. Yokobe, and K. Hakamada

Journal of Geophysical Research 106 巻頁： 15,677－15,686 2001年

Polar Low-speed Solar Wind at the Solar Activity Maximum 査読有り

Ohmi, T., M. Kojima, A. Yokobe, M. Tokumaru, K. Fujiki, and K. Hakamada

Journal of Geophysical Research 106 巻頁： 24,923－24,936 2001年

Microwave Observation of Eruptive Solar Events with and without Flare Activity(共著) 査読有り

Astrophysical Journal 533 巻頁： 557 2000年

Microwave Preflare Enhancement and Depletion in Long Duration Events 査読有り

Advanced Space Research 26 巻 ( 3 ) 頁： 477 2000年

Three-dimensional propagation of interplanetary disturbances detected with radio scintillation measurements at 327MHz(共著) 査読有り

Journal of Geophysical Research 105 巻 2000年

Low speed solar wind from the vicinity of solar active regions(共著) 査読有り

Journal of Geophysical Research 104 巻頁： 16993 1999年

The highest solar wind velocity in a polar region estimated from IPS tomography analysis(共著) 査読有り

Space Science Review 87 巻頁： 237 1999年

17 and 34 GHz Observations of the Sun with the Nobeyama Radioheliograph 査読有り

Proceedings of Nobeyama Symposium, NRO Report 479 巻頁： 249 1998年

Corotating Ion Events Associated with Cosmic Ray Modulation 査読有り

J. Geomag. Geoelectr. 47 巻頁： 1333 1995年

Energy Loss Straggling of Heavy Charged Particles in thick Silicon Absorbers 査読有り

Journal of the Physical Society of Japan 63 巻 ( 1 ) 頁： 92 1994年

Rapid Recovery of Anomalous Cosmic Ray Flux at 1 AU in Solar Cycle 22 査読有り

Geophysical Research letter 21 巻 ( 25 ) 頁： 3027 1994年

The Energetic Particle Spectrometer HEP onboard the GEOTAIL Spacecraft 査読有り

J. Geomag. Geoelectr. 46 巻頁： 713 1994年

Determination of Charge and Energy for Particles Penetrating a Silicon △E×E Telescope in Space Radiation 査読有り

Jpn. J. Appl. Phys. 33 巻頁： 4106 1994年

Geometric Factor of Geotail HEP-MI and-HI Telescopes

Bulletin of Science and Engineering Research Laboratory, Waseda Univ. ( 139 ) 頁： 1 1992年

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