2024/03/27 更新

写真a

フジキ ケンイチ
藤木 謙一
FUJIKI, Ken'ichi
所属
宇宙地球環境研究所 基盤研究部門 太陽圏研究部 助教
大学院担当
大学院理学研究科
職名
助教
連絡先
メールアドレス

学位 1

  1. 博士(学術)

研究分野 2

  1. その他 / その他  / 惑星間空間物理学

  2. その他 / その他  / 太陽物理学

現在の研究課題とSDGs 2

  1. 太陽風速度構造の研究

  2. IPS観測用大型UHFアンテナの開発

経歴 1

  1. 名古屋大学   宇宙地球環境研究所 基盤研究部門 太陽圏研究部   助教

    2015年10月 - 現在

学歴 1

  1. 総合研究大学院大学   数物科学研究科

    1994年4月 - 1997年9月

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    国名: 日本国

所属学協会 6

  1. 地球電磁気・地球惑星圏学会

  2. 日本物理学会

  3. 日本天文学会

  4. 日本物理学会

  5. 日本天文学会

  6. 地球電磁気・地球惑星圏学会

▼全件表示

 

論文 96

  1. 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

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/ac3c46

    Web of Science

  2. 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

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/ac1862

    Web of Science

  3. 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

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-019-1487-6

    Web of Science

  4. 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

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    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1186/s40623-019-1019-5

    Web of Science

  5. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/836/1/108

    Web of Science

  6. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.asr.2022.06.029

  7. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.asr.2022.09.028

  8. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-023-02220-8

  9. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/acd000

  10. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-023-02169-8

  11. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-023-02116-7

  12. 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

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1186/s40623-020-01345-5

    Web of Science

  13. 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

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1029/2018SW002098

    Web of Science

  14. 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

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    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)  

    DOI: https://doi.org/10.1007/s11207-019-1418-6

    arXiv

  15. 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

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    掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-019-1418-6

    Web of Science

    arXiv

  16. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1051/0004-6361/201832981

  17. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/2017JA025014

    Web of Science

    Scopus

  18. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-017-1066-7

    Web of Science

  19. 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

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    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.

  20. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  21. 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

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    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)  

    DOI: 10.1007/s11207-015-0742-8

  22. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/2015JA021123

  23. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  24. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1088/0004-637X/795/1/69

  25. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-014-0472-3

  26. 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

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    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)  

    DOI: 10.1002/2014GL059391

  27. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-013-0297-5

  28. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-012-9993-9

  29. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.4811018

  30. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.4811041

  31. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-012-0207-2

  32. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: doi:10.1088/0067-0049/203/1/1

  33. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  34. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1029/2011JA017379

  35. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-012-9993-9

  36. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  37. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1007/s11207-011-9864-9

  38. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 2011arXiv1112.2967B

  39. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: doi:10.1029/2011GL049227

  40. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  41. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: DOI: 10.1007/s11207-011-9864-9

  42. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: doi:10.1016/j.jastp.2010.11.023

  43. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: doi:10.1016/j.jastp.2010.10.007

  44. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  45. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  46. 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

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    担当区分:筆頭著者   記述言語:英語  

  47. 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

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    記述言語:英語  

  48. 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

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    記述言語:英語  

  49. 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

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    記述言語:英語  

  50. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  51. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  52. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  53. 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

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    記述言語:英語  

  54. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  55. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  56. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  57. 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

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    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.

  58. *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

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    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.

  59. 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

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    記述言語:英語  

  60. 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

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    記述言語:英語  

  61. 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

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    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.

  62. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  63. 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

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    記述言語:英語  

  64. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  65. *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

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    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.

  66. 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

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    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.

  67. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  68. 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

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    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.

  69. 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

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    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

  70. 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

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    担当区分:筆頭著者   記述言語:英語  

  71. 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

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    記述言語:英語  

  72. 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

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    記述言語:英語  

  73. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  74. 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

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    記述言語:英語  

  75. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  76. 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

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    記述言語:英語  

  77. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  78. 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

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    記述言語:英語  

  79. *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

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    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)  

  80. 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

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    担当区分:筆頭著者   記述言語:英語  

  81. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  82. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  83. 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

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    記述言語:英語  

  84. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  85. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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

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

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    担当区分:筆頭著者   記述言語:英語  

  87. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  88. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  89. 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

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    担当区分:筆頭著者   記述言語:英語  

  90. 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

     詳細を見る

    担当区分:筆頭著者   記述言語:英語  

  91. Corotating Ion Events Associated with Cosmic Ray Modulation 査読有り

    J. Geomag. Geoelectr.   47 巻   頁: 1333   1995年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  92. 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

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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

    J. Geomag. Geoelectr.   46 巻   頁: 713   1994年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  94. 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

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  95. 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

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

  96. Geometric Factor of Geotail HEP-MI and-HI Telescopes

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

     詳細を見る

    記述言語:英語  

▼全件表示

書籍等出版物 3

  1. An Upgrade of Nobeyama Radioheliograph to a Dual-Frequency (17 and 34 GHz)System (共著)

    Coronal Physics From Radio and Space Observation (Lecture Note in Physics)  1997年 

     詳細を見る

    記述言語:英語

  2. Cross-Calibration of Far UV Spectra of Solar System Objects and the Heliosphere

    Bzowski, Maciej; Sokół, Justyna M.; Tokumaru, Munetoshi; Fujiki, Kenichi; Quémerais, Eric; Lallement, Rosine; Ferron, Stéphane; Bochsler, Peter; McComas, David J.( 担当: 共著)

    SPRINGER  2013年4月 

     詳細を見る

    記述言語:英語

  3. Solar wind properties from IPS observations,in "The Sun and the Heliosphere as an Integrated System", Editors: Giannina Poletto and Steven T. Suess

    Kojima, M., K. Fujiki, M. Hirano, M. Tokumaru, T. Ohmi, and K. Hakamada( 担当: 共著)

    Kluwer Academic Publishers  2004年 

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    記述言語:英語

    The solar corona changes its structure dramatically with solar activity. As a consequence, the solar wind also changes dynamically. Coronal holes and physical parameters in the coronal play an important role in determining the solar wind speed and the solar wind structure. We have been studying several interesting solar wind features found in the latitudinal structure observed by Ulysses; namely, how they depend on the solar cycle and what coronal parameters determine it. We proposed a model to determine the solar wind velocity structure.
    Since Hewish et al. (1964) discovered the interplanetary scintillation (IPS) phenomena, the IPS method has been one of the few devices which can be used to observe solar wind in three-dimensional space. However, because of the line-of-sight integration effect of IPS, solar wind had to be studied with blurred images. In the late 1990s, we developed a new method of IPS observation and analysis which can deconvolve the line-of-sight integration effect. Today we can obtain unbiased solar wind images with high spatial resolution from IPS observations.
    The Ulysses spacecraft has been observing detailed structures of solar wind in three dimensions. However, Ulysses takes ten months even to make a rapid latitudinal scan from the south to north poles. IPS measurements have several advantages in comparison with spacecraft measurements. IPS can observe three-dimensional solar wind in a short time, and the observations can be carried out consistently over a solar cycle. Making use of these IPS advantages, we conducted the present study.
    In the ascending/descending phase, the latitudinal width of the low-speed region extends/shrinks, and the velocity gradient in the high-latitude high-speed region becomes steeper/gradual. On the other hand, the velocities in the polar region and the velocity gradient between low-speed and high-speed regions do not change. When, at solar maximum, the polar coronal hole area shrinks and nearly vanishes, the v

MISC 4

  1. 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 Astrophysics618 巻   2018年8月

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    記述言語:英語   掲載種別:速報,短報,研究ノート等(学術雑誌)  

    DOI: 10.1051/0004-6361/201832981

  2. Rarefaction of the Very Slow (&lt;350 km/s) Solar Wind in Cycle 24 Compared With Cycle 23

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

    Journal of Geophysical Research: Space Physics123 巻 ( 4 ) 頁: 2520 - 2534   2018年4月

     詳細を見る

    記述言語:英語   掲載種別:速報,短報,研究ノート等(学術雑誌)   出版者・発行元:Blackwell Publishing Ltd  

    We investigate long-term variation of the very slow solar wind (VSSW), whose speed is less than 350 km/s, during the period between 1997 and 2015, that is, Cycles 23 and 24, using interplanetary scintillation measurements, which enable determination of the global distribution of the flow speed and the electron density fluctuation level ΔNe. We find that the occurrence rate of VSSW increases in the maximum phase of the solar cycle, and it was mostly associated with high ΔNe in Cycle 23. However, the VSSW is found to be more associated with low ΔNe in Cycle 24. This fact is consistent with an increased occurrence of the low-density VSSW observed in situ in Cycle 24. These facts, which are considered to be a manifestation of weak solar activity in this cycle, suggest that the VSSW has become significantly rarefied in recent years. We identify the source region of the VSSW on the photosphere using a potential field analysis and examine the magnetic field properties of the VSSW source. We find that the low-ΔNe VSSW is associated with a smaller expansion factor and possibly a slightly weaker photospheric field strength than the high-ΔNe VSSW. The results obtained here may suggest that more open magnetic field areas producing the VSSW in Cycle 24 are formed in the quiet Sun region, which is associated with a lower mass flux supply into the corona, than those in Cycle 23.

    DOI: 10.1002/2017JA025014

    Scopus

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

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

    SOLAR PHYSICS292 巻 ( 3 )   2017年3月

     詳細を見る

    記述言語:英語   掲載種別:速報,短報,研究ノート等(学術雑誌)   出版者・発行元:SPRINGER  

    We investigate the relation between coronal hole (CH) areas and solar wind speeds during 1995 - 2011 using the potential field (PF) model analysis of magnetograph observations and interplanetary scintillation (IPS) observations by the Institute for Space-Earth Environmental Research (formerly Solar-Terrestrial Environment Laboratory) of Nagoya University. We obtained a significant positive correlation between the CH areas (A) derived from the PF model calculations and solar wind speeds (V) derived from the IPS observations. The correlation coefficients between them are usually high, but they drop significantly in solar maxima. The slopes of the A-V relation are roughly constant except for the period around solar maximum, when flatter or steeper slopes are observed. The excursion of the correlation coefficients and slopes at solar maxima is ascribed partly to the effect of rapid structural changes in the coronal magnetic field and solar wind, and partly to the predominance of small CHs. It is also demonstrated that V is inversely related to the flux expansion factor (f) and that f is closely related to A(-1/2); hence, V alpha A(1/2). A better correlation coefficient is obtained from the A(1/2) - V relation, and this fact is useful for improving space weather predictions. We compare the CH areas derived from the PF model calculations with He I 1083 nm observations and show that the PF model calculations provide reliable estimates of the CH area, particularly for large A.

    DOI: 10.1007/s11207-017-1066-7

    Web of Science

  4. High-latitude Conic Current Sheets in the Solar Wind

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

    ASTROPHYSICAL JOURNAL836 巻 ( 1 )   2017年2月

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    記述言語:英語   掲載種別:速報,短報,研究ノート等(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of coniclike magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.

    DOI: 10.3847/1538-4357/836/1/108

    Web of Science

講演・口頭発表等 21

  1. ISEEの太陽圏研究について

    藤木謙一

    太陽圏の次世代研究検討会  2024年3月6日  名古屋大学宇宙地球環境研究所

     詳細を見る

    開催年月日: 2024年3月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:名古屋大学  

  2. Decades of Solar Wind Structure and Its Origins: Insights from IPS Observations and PFSS Analysis 国際会議

    2023年10月11日  名古屋大学宇宙地球環境研究所

     詳細を見る

    開催年月日: 2023年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:名古屋大学  

  3. A Periodic Variation of Solar Wind Origins in Solar Cycles

    Ken'ichi Fujiki, Kazumasa Iwai, and Munetoshi Tokumaru

    SGEPSS 2023 Fall meeting  2023年9月24日 

     詳細を見る

    開催年月日: 2023年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:Tohoku University  

  4. Distribution of Solar Wind Sources at the Solar Surface from 1985 to 2016

    Fujiki, K.; Tokumaru, M.; Iwai, K.

    SGEPSS 2021  2021年11月2日  Society of Geomagnetism and Earth, Planetary and Space Sciences

     詳細を見る

    開催年月日: 2021年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:online  

  5. Simple Estimation of the Global Solar Wind Structure

    Japan Geoscience Union Meeting 2021  2021年6月5日  Japan Geoscience Union

     詳細を見る

    開催年月日: 2021年5月 - 2021年6月

    記述言語:日本語   会議種別:ポスター発表  

    開催地:online  

  6. Reconstruction of Global Solar Wind Structure from 1975 to 2016 by Using Interplanetary Scintillation and Solar Magnetogram Observations 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru

    AOGS 15th Annual Meeting 

     詳細を見る

    開催年月日: 2018年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii, USA   国名:アメリカ合衆国  

  7. Reconstruction of global solar wind structure from 1975 to 2016

    Ken'ichi Fujiki, Munrtoshi Tokumaru, Kazumasa Iwai

    JpGU 2018 

     詳細を見る

    開催年月日: 2018年5月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  8. Solar Wind Structure and Coronal Hole Distribution 国際会議

    ISEE Founding Symposium 

     詳細を見る

    開催年月日: 2015年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  9. Investigations of Inner- and Outer-Heliosphere Using STEL-IPS 国際会議

    FUJIKI, Ken'ichi, TOKUMARU, Munetoshi, KOJIMA, Masayoshi, IJU, Tomoya, Haruichi WASHIMI, Keiji HAYASHI

    AOGS 12th Annual Meeting 

     詳細を見る

    開催年月日: 2015年8月

    記述言語:英語   会議種別:ポスター発表  

    国名:シンガポール共和国  

  10. Test of Solar Wind Models Using Interplanetary Scintillation Data 国際会議

    FUJIKI, Ken'ichi TOKUMARU, Munetoshi, KOJIMA, Masayoshi, IJU, Tomoya

    AOGS 11th Annual Meeting 

     詳細を見る

    開催年月日: 2014年7月 - 2014年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Royton Sapporo Hotel, Japan   国名:日本国  

  11. Upgrade of STEL IPS system 国際会議

    Ken'ichi Fujiki

    IPS Worksiop 2013 

     詳細を見る

    開催年月日: 2013年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Nagoya University, Japan   国名:日本国  

  12. Relationship between solar wind speed and coronal magnetic field properties (I) 国際会議

    Ken'ichi Fujiki, Masayoshi Kojima, Munetoshi Tokumaru, Tomoya Iju

    International CAWSES-II Symposium 

     詳細を見る

    開催年月日: 2013年11月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Nagoya University, Japan   国名:日本国  

  13. Solar Wind Observations Using STEL 327-MHz Interplanetary Scintillation System 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru, Masayoshi Kojima, Tomoya Iju

    2013 Asia-Pacific Radio Science Conference 

     詳細を見る

    開催年月日: 2013年9月

    記述言語:英語   会議種別:ポスター発表  

    開催地:Howard International House, Taipei, Taiwan   国名:台湾  

  14. SOLAR WIND FORECAST BY USING STELAB-IPS 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru, Tomoya Iju

    AOGS-AGU (WPGM) Joint Assembly 

     詳細を見る

    開催年月日: 2012年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Resorts World Convention Centre, Singapore   国名:シンガポール共和国  

  15. Solar Wind Observations Using STELab-IPS Arrays In Japan 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru, Masayosi Kojima

    ASJ-KAS Joint Sessions on Space Weather and Space Climate 

     詳細を見る

    開催年月日: 2011年10月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Jeju, Korea   国名:大韓民国  

  16. Global Solar Wind Structure Observed with STELab-IPS 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru, Masayoshi Kojima

    AOGS 2011 

     詳細を見る

    開催年月日: 2011年8月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Taipei International Convension Centre   国名:台湾  

  17. Variation of Global Solar Wind Structure Observed with STELab-IPS 国際会議

    Ken'ichi Fujiki

    IPS Workshop 

     詳細を見る

    開催年月日: 2011年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Aberystwyth University   国名:グレートブリテン・北アイルランド連合王国(英国)  

  18. SOLAR WIND FORECAST BY USING INTERPLANETARY SCINTILLATION OBSERVATION 国際会議

    Ken'ichi Fujiki, Hiroaki Ito, Munetoshi Tokumaru

    Solar Wind 12 

     詳細を見る

    開催年月日: 2009年6月

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:St Malo, France   国名:フランス共和国  

  19. Solar wind studies with multi-station interplanetary scintillation observation 国際会議

    Ken'ichi Fujiki, Munetoshi Tokumaru, Masayoshi Kojima

     詳細を見る

    開催年月日: 2008年11月

    記述言語:日本語   会議種別:口頭発表(一般)  

    国名:日本国  

  20. Reconstruction of global solar wind structure from 1975 to 2016 国際会議

    Ken'ichi Fujiki, Munrtoshi Tokumaru, Kazumasa Iwai

    日本地球惑星科学連合2018年大会  2018年5月20日 

     詳細を見る

    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:幕張メッセ  

  21. Reconstruction of Global Solar Wind Structure from 1975 to 2016 by Using Interplanetary Scintillation and Solar Magnetogram Observations

    Ken'ichi Fujiki, Munetoshi Tokumaru

    AOGS 15th Annual Meeting  2018年6月3日 

     詳細を見る

    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:Honolulu, Hawaii, USA  

▼全件表示

Works(作品等) 1

  1. 野辺山電波ヘリオグラフの像処理法の開発

    1996年
    -
    1997年

科研費 1

  1. 特異な太陽ダイナモ活動に伴う太陽圏全体構造の変動の解明

    研究課題/研究課題番号:25247079  2013年4月 - 2018年3月

    徳丸 宗利

      詳細を見る

    担当区分:連携研究者 

    異常に弱い活動度を示すサイクル24における太陽風の全球的分布とその時間発展を明らかにするため、改良された名古屋大学ISEEの多地点IPSシステムを用いて連続観測を行った。その結果、本サイクルにおいて速度が350km/s以下(超低速)で密度が高速風のように低い太陽風の出現が顕著に増えていること、開いた磁場領域の面積や磁束管拡大率と速度の関係には低い太陽活動の影響は見られないこと、などが判った。これらの事実は太陽活動の著しい低下に伴ってコロナからの質量供給率またはエネルギー注入率が減少していること示唆し、超低速風の領域でその効果が特に顕著であることは太陽風加速機構を探る重要な手掛かりを与える。