2002 Fiscal Year Final Research Report Summary
Observational approaches for resolving the solar wind acceleration mechanism
| Project/Area Number |
12440130
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | Nagoya University |
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Principal Investigator |
KOJIMA Masayoshi Nagoya University, Solar-Terrestrial Environment Laboratory, Professor, 太陽地球環境研究所, 教授 (70023687)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Keiji Nagoya University, Solar-Terrestrial Environment Laboratory, COE research associate, 太陽地球環境研究所, COE研究員
FUJIKI Ken'ichi Nagoya University, Solar-Terrestrial Environment Laboratory, Assistant Professor, 太陽地球環境研究所, 助手 (20303597)
TOKUMARU Munetoshi Nagoya University, Solar-Terrestrial Environment Laboratory, Associate Professor, 太陽地球環境研究所, 助教授 (60273207)
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| Project Period (FY) |
2000 – 2002
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| Keywords | solar wind / CME / radio observation / acceleration mechanism / interplanetary plasma / interplanetary shock |
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| Research Abstract |
(1) Properties of slow solar wind originated from a small coronal hole
It is well-known that fast solar wind originates from polar coronal holes. On the other hand, the origin of slow solar wind is complex in comparison with that of fast solar wind. Thus we have analyzed the origin of the slow solar wind by using IPS tomography velocity maps) photospheric magnetograms (Kitt Peak/NSO) and coronal hole boundary maps obtained from HeI1803 nm observation (Kitt Peal/NSO). We found several slow solar wind regions originated from small coronal holes at mid-latitude. Next we analyzed plasma parameters such as temperature, density, helium abundance, and their fluctuation levels using in situ measurements data. As results, we also found that plasma parameters of the slow solar wind originated from the small coronal hole resemble those of fast solar wind.
(2) Spatial structure of ICMEs
We have analyzed in this study g-value data for two IOME events, which occurred on June 2000 and 1998 September. It is found from the model fitting analysis that an angular span for these ICME events is not isotropic. Such a troidal-shape structure also has been disclosed from the model fitting analysis for the ICME event associated with an X5.7/3B flare on July 14, 2000. The E-W angular span is about 7 larger than the N-S span for this event. While angular anisotropy estimated for 2000 June and 1998 Sep. events is smaller than one for the 2000 July event, we consider that such angular anisotropy might be a common feature for a certain class of ICME events. A possible agency to cause the angular anisotropy of ICME structure is either an interaction with the slow speed component of the solar wind or the effect of the magnetic flux rope.
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Research Products
(32 results)
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[Publications] Moran, P.J., S.Ananthakrishnan, V.Balastibramanian, A.R.Breen, A.Canals, R.A.Fallows, P.Janardhan, M.Tokumaru, P.J.S.Williams: "Observations of interplanetary scintillation during the 1998 Whole Sun Month : A comparison between EISCAT, ORT and Nagoya data"Annales Geophysicae. 18. 1003-1008 (2000)
Description
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[Publications] Fry, C.D., Sun, W., Deehr, C.S., Dryer, M., Smith, Z., Akasofu, S.-I., Tokumaru, M., Kojima, M.: "Improvements to the HAF solar wind model for space weather predictions"J.Geophys.Res. Vol.106,(2000JA000220). (2001)
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[Publications] Manoharan, P.K., M.Tokumaru, M.Pick, P.Subramanian, F.M.Ipavich, K.Schenk, M.L.Kaiser, R.P.Lepping, A.Vourlidas: "Coronal mass ejection of July 14, 2000 Flare Event : Imaging from near-Sun to Earth environment."Astrophys.J.. 559. 1180-1189 (2001)
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[Publications] Kojima, M., Fujiki, K., Ohmi, T., Tokumaru, M., Yokobe, A., Hakamada, K.: "Latitudinal velocity structures up to the solar poles estimated from interplanetary scintillation tomography analysis"J.Geophys.Res.. 106. 24923-24936 (2001)
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