本論文利用福爾摩沙衛星一號(ROCSAT-1)搭載電離層電動效應儀探測之正離子濃度、溫度和電漿速度及全球電離層圖(Global Ionosphere Map, GIM)長期連續觀測之全球電離層全電子含量(Total Electron Content, TEC)研究2002年3月31日台灣花蓮M6.8地震(331地震)期間之電離層異常前兆現象。利用福衛一號前後45天正離子資料建立參考背景，與觀測值進行分析比對。正離子濃度方面，結果顯示於331地震前1-5天，震央南方區域有異常減少現象，盒鬚圖分析其減少量為統計顯著。其對應之電漿飄移速度向南向下的異常現象，推論為地震前之異常西向電場。另一方面，分析同一時段之全球電離層圖，在震央上空之全電子含量也觀察到負異常現象，並且在地震天兩天前最為顯著，空間分析顯示震央附近出現連續22小時以上之異常，而對全球負異常發生區域做統計分析，累積異常次數證實地震前五天0600-1200UT異常最頻繁地區分布於震央周遭。;In this study we use ion density, ion temperature and ion drift velocity data observed by Ionospheric Plasma and Electrodynamics Instrument (IPEI) on Rocsat-1 (also named Formosat-1) satellite and total electron content (TEC) of CODE global ionosphere map (GIM) continuously observed the ionosphere, analyzing the Seismo-ionospheric precursor (SIPs) during 31st March 2002 M6.8 Taiwan Hualien 331 earthquake. Building the model of IPEI data to compare with the observation data, ion density result shows the decreasing anomaly appeared in 1-5 days before the earthquake, and using boxplot to define the significant difference between observation and background references. The plasma drift velocity shows equatorial ward and downward anomaly which indicate the anomalous westward electric field. On the other hand, analyzing the GIM TEC in the same period, the significant decreasing anomaly appeared. In spatial analysis, the phenomenon last more than 22 hours and distributed near to the epicenter. The most frequently happened region of decreasing anomaly during 0600-1200UT in the 1-5 days before the 331 earthquake is also close to the epicenter.
