中華衛星一號觀測磁暴時期電離層電漿槽中低緯度邊界位置及波動現象之研究; Investigation of storm-time low latitude ionosphere trough and the associated plasma wave phenomena using ROCSAT-1/IPEI data

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Title:	中華衛星一號觀測磁暴時期電離層電漿槽中低緯度邊界位置及波動現象之研究;Investigation of storm-time low latitude ionosphere trough and the associated plasma wave phenomena using ROCSAT-1/IPEI data
Authors:	鍾志斌;Tzu-Ping Chung
Contributors:	太空科學研究所
Keywords:	中華衛星一號;磁暴;電離層電漿槽;ROCSAT1;storm;trough
Date:	2004-06-17
Issue Date:	2009-09-22 09:46:38 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	摘要中華衛星一號在離地面高約600 km處；傾角35度的圓形軌道上繞行已逾五年。它的軌道範圍涵蓋地理緯度南北緯35度，最大磁緯度達50度。本論文利用中華衛星一號上的電離層電漿電動儀IPEI在2001 3/31的磁暴發生期間內收集到的電離層電漿濃度、溫度、運動速度、離子成份等資料，分析在這個磁暴事件發生期間電離層電漿槽邊界向中低緯度擴張及隨地方時（LT）分佈的情形，並對電離層電漿槽邊界做波譜分析和觀測存在於此的極向電場大小，以利探討在這個邊界上所產生的不規則體的波擾動空間尺度及其背後機制。在2001 3/31這個磁暴事件中（09:00~10:00 UT間DST最低約達-390 nT，kp>7）可以發現電離層電漿槽邊界出現在磁緯度-40°~-43°之間，在半夜00:00 LT以前的緯度位置有隨著地方時增加而下移的趨勢，而在高於這個電漿槽邊界磁緯度的區域則有速度極大約1000 m/s~1600 m/s電離層電漿向西的移動，這個區域也同時觀察到有溫度及成份的變化﹔此區域所計算的電場則顯示了隨緯度位置越高而增加的趨勢，而波譜分析顯示低緯邊界可能存在甚強10 km-100 m尺度的電漿不規則體結構。類似電磁波的離子速度波動也在後半夜的這個邊界上被觀察到。 Abstract The ROCSAT-1 satellite was launched into a circular orbit at about 600 km altitude with an inclination of 35 degrees. The onboard ionosphereic plasma and electrodynamic instrument (IPEI) takes in-situ measurements of ionospheric parameters. The ROCSAT-1 orbits cover the geographic latitude range between 35°N and 35°S (maximum magnetic latitude, about ±50°). The data used here include ionospheric ion density, temperature, ion drift velocity and ions composition measured by IPEI during the great magnetic storm on March 31 and April 1, 2001. These data are used to demonstrate the presence and the local time (LT) distribution of the ionosphere plasma density troughs whose equator-ward boundaries extended to the lower mid-latitude region during the heights of this storm. Furthermore, wave spectra of ion density, and the two cross-track velocity components at equatorward boundaries of troughs are analyzed to investigate the spatial scales of the irregularities and the associated processes. During this storm (DST is at the lowest –390 nT in 09:00 ~10:00 UT, kp > 7), the trough equatorward boundary were found at magnetic latitudes as low as -40° ~ -43°. In pre-midnight sector, the latitude of this boundary moved equator-ward as local time increasing. Inside the trough region, at latitudes which are higher than those of trough equatorward boundary, large westward ion drifts were detected (about 1000 m/s ~ 1600 m/s). In addition, significant disturbances in temperature and ion composition were observed inside the trough region. The poleward electric field observed in this region was increasing with increasing latitude in the pre-midnight sector. The results of spectral analysis indicate that there exist irregularity structures with spatial scale size from 100 m to 10 km, and electromagnetic wave signatures at the eguatorward boundary of the trough.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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