在中緯度的電離層F層中，距離地球表面上空600公里處，平時N 、NO 及O 等重離子的含量幾乎不可能超過1%。然而在西元2003年11月20日當天，磁暴(最低Dst =-472)發生期間，透過中華衛星一號上之電離層電漿及電動效應儀(IPEI)卻探測到在磁暴初始恢復期UT 19:27 ~ 19:37、UT 20:57 ~ 21:15與UT 22:33 ~ 22:51三個時段中，NO 離子密度超過全離子濃度的5%，有時甚至高達20%以上，且沿衛星軌道連續被觀測跨4500公里。本文利用IPEI在當天所收集到的相關資料，研究中緯度重離子(主要是NO )異常現象的發生機制。從觀測到這些重離子的緯度及地方時及這些離子的流速方向，我們推斷這些重離子可能源自中緯度的副極光區，這些離子受到極向SAPS(副極光區極化電漿流)電場作用向西飄移也沿磁力線向中低緯度傳播。 Heavy ions such as N 、NO and O are hardly (< 1%) observed at 600 km altitude in the mid-latitude ionosphere under geo-magnetically quiet conditions. However, the ROCSAT-1 IPEI payload did observe abnormal percentage content (5% ~20%) of NO which spanned large region (4500km) along the satellite orbit for three consecutive passes during the early recovery phase of the November 20, 2003 great magnetic storm. Specifically, the IPEI saw the abnormal NO events in three UT intervals including UT 19:27 ~ 19:37, UT 20:57 ~ 21:15 and UT 22:33 ~ 22:51. This thesis studies the possible mechanism of the anomalous increase of heavy ions (mainly NO ) in mid-latitude using the data of ion density, ion composition and drift velocities from IPEI for that day. From the correlations among the above IPEI parameters and their dependencies on local time and latitude, we infer that the heavy ions may originate from the subauroral latitudes, meanwhile these heavy ions were driven by the pole-ward SAPS (Subauroral Polarization Stream) electric fields to drift westward and equator-ward toward middle latitudes.
