臺灣博碩士論文加值系統

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.

目錄
頁次
摘要………………………………………………………………………i
英文摘要…………………………………………………………………ii
致謝………………………………………………………………………iii
目錄………………………………………………………………………iv
圖目錄……………………………………………………………………vi
表目錄……………………………………………………………………viii
第一章 緒論
◎1.1簡介電離層…………………………………………………………1
◎1.2 磁暴造成之電離層電漿槽(trough)現象………………………1
◎1.3 研究目的…………………………………………………………4
第二章 儀器簡介
◎2.1 中華衛星一號簡介………………………………………………6
◎2.2 電離層電漿及電動效應儀( IPEI)………………………………7
第三章 資料處理與分析
◎3.1 資料選取與分析方式……………………………………………12
◎3.2 電漿槽區域特徵及定義中低緯度邊界位置……………………13
◎3.3 電漿槽區域內離子濃度隨緯度之分佈…………………………15
◎3.4 電漿槽中低緯度邊界上離子速度、濃度波譜…………………16
◎3.5 電漿槽區域內及中低緯度邊界上之電場計算…………………18
第四章 觀測結果與討論
◎4.1 電漿槽的衛星觀測……………………………………………19
◎4.2 電漿槽的中低緯度邊界位置與Local Time…………………21
◎4.3 電漿槽中低緯度邊界相關的波現象…………………………23
◎4.4 電漿槽區域內及中低緯度邊界的極向電場…………………24
第五章 總結……………………………………………………………26
參考文獻…………………………………………………………………28
附錄A 本文內容圖………………………………………………………29
附錄B
16:30~17:00 UT、19:40~20:20 UT、21:20~21:50 UT、23:00~23:30 UT時段衛星所提供觀測的物理參數圖………………………………50


圖目錄
圖1.1電離層離子濃度的垂直高度分佈圖…………………………………29
圖1.2地球磁層結構…………………………………………………………29
圖1.3 電場投射入電離層造成離子V=E×B/B2運動示意圖…………………30
圖2.1 中華衛星一號外型……………………………………………………30
圖2.2 IPEI儀器外觀…………………………………………………………31
圖2.3中華一號衛星座標定義示意圖………………………………………31
圖2.4離子流向量測儀構造示意圖…………………………………………32
圖3.1 2001 3/31號的磁暴事件DST，Kp，IMF(Bz)的時間變化…………32
圖3.2粗略的quick look資料圖……………………………………………33
圖3.3 衛星提供觀測的物理參數…………………………………………33
圖3.4 衛星LT前半夜所觀測到的資料對磁緯度作圖……………………34
圖3.5 LT>00:30跟LT<00:30的離子速度跟濃度隨緯度分佈……………35
圖3.6五個觀測時段(路線)的磁緯度與LT極座標分佈圖………………36
圖3.7電漿槽區域內濃度隨磁緯度位置變化……………………………37
圖3.8a、b、c 電漿槽後半夜的低緯度邊界上離子濃度和離子速度Vy、Vz的波譜分析圖…………………………………………………………………38、39、40
圖3.9a、b、c 電漿槽區域內的離子濃度和離子速度Vy、Vz的波譜分
析圖………………………………………………………………41、42、43
圖3.10a、b、c電漿槽前半夜的低緯度邊界上離子濃度和離子速度Vy、Vz的波譜分析圖…………………………………………………………………44、45、46
圖3.11 IGRF模型提供的磁場向量表示法…………………………………46
圖4.1 磁暴事件DST與衛星觀測到電漿槽區域的五個時段………………47
圖4.2 衛星觀測所行經的路徑位置分佈圖………………………………47
圖4.3a 電漿槽區域內在七個LT時區的極向電場大小隨磁緯度分佈
………………………………………………………………………………48
圖4.3b 電漿槽區域內在七個LT時區的離子西向速度大小隨磁緯度分佈.………………………………………………………………………………49

表目錄
表2.1中華衛星一號的基本概述……………………………………………6
表2.2電離層電漿及電動效應儀之概述……………………………………10
表4.1電漿槽區域的低緯度邊界上的極向電場及對應的L值……………25

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