徑向行星際磁場下日側極光與電離層對流型態;Dayside aurora and ionospheric convection under radial interplanetary magnetic fields

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Title:	徑向行星際磁場下日側極光與電離層對流型態;Dayside aurora and ionospheric convection under radial interplanetary magnetic fields
Authors:	李先明;Li, Hsien-Ming
Contributors:	太空科學與工程研究所
Keywords:	日側極光;電離層對流;徑向行星際磁場;磁重聯;dayside aurora;ionospheric convection;radial interplanetary magnetic field;magnetic reconnection
Date:	2023-07-25
Issue Date:	2024-09-19 14:49:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究探討2014年1月4日徑向行星際磁場事件分別對日側極光與電離層對流型態的影響程度。過去的研究偏重在對磁層的影響層面或是特殊極光現象上，不同於過去研究，我們整合來自挪威Svarlbard島上的全天影像儀、芬蘭Hankasalmi高頻雷達、DMSP衛星及SuperMAG觀測資料，實施日側極光與電離層對流型態分析。分析的結果表明，日側極光出現三類不同的型態：侷限在某個緯度範圍內亮度增加、極向運動與赤道向運動。電離層對流型態出現太陽向流、反太陽向流以及兩者共存現象，從日側極光與電離層對流型態說明徑向行星際場具有使場向電流增加與磁重聯的特性，增強的場向電流從DMSP衛星與SuperMAG觀測資料間接證明源自於磁鞘高速流的作用，不同於南向與北向行星際磁場對電離層對流有固定且可預測的對流型態，這些對流型態在徑向行星際磁場期間交替出現，未來在電離層對流型態預報上必須注意徑向行星際磁場。;This research explored the influence of the radial interplanetary magnetic field event on January 4, 2014 on the dayside aurora and ionospheric convection patterns, respectively. Previous studies focused on the impact on the magnetosphere or special aurora phenomena. Unlike previous studies, we coordinated the observations obtained from the all-sky imager on Svarlbard Island in Norway, the Hankasalmi high-frequency radar in Finland, DMSP satellites and SuperMAG data to examine the dayside aurora and ionospheric convection patterns for radial interplanetary magnetic field. The results of the analysis showed that there are three different patterns of dayside aurora: brightness increase limited to a certain latitude range, polar movement and equatorial movement. The convection patterns in the ionosphere included sunward flow, anti-sunward flow, and the coexistence of both. These patterns indicated that the radial interplanetary magnetic field had the characteristics of increasing the field-aligned current and magnetic reconnection. The enhanced field-aligned current indirectly proved from the observation data of DMSP satellite and SuperMAG that it originated from the effect of high-speed flow in the magnetosheath. Ionospheric convection was different from the fixed and predictable convection patterns under the southward and northward interplanetary magnetic fields. These convection patterns appeared alternately during the radial interplanetary magnetic field, and the radial interplanetary magnetic field must be paid attention to in the forecast of the ionospheric convection pattern in the future.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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