在赤道地區日落後電離層F 層，因為突增的東向電場(Eastward Electric Field)，造成垂直上昇漂移速度(Vertical Drifts)的增大，使得電離層F 層向上抬升，讓不規則體產生的機率提高。 我們利用中華衛星一號上的電離層電漿電動效應儀(IPEI)所量測 到的離子資訊，從2000 年2 月份到2004 年1 月份，取出K p<3 的資料，分成3 個當地時段(Local Time) ，在赤道地區對日落後的不規則體發生的機率特性，隨著經度、當地時間以及季節的變化，與其相對應的垂直上昇速度作一系列的相關性研究。觀測結果發現，在日落後其當地時段(18 LT ~19 LT)的垂直上昇漂移速度突增，與不規則體的產生有很大的相關性；而且磁偏角會影響到四個季節的垂直上昇漂移速度的變化，所以也會造成在其相對應的季節有不同的不規則體的產升機率。 Large vertical drifts driven by eastward electrical fields appear in the post-sunset equatorial F region. These enhanced vertical drifts drive the ionospheric F region to high altitude and results in many scintillation-producing irregularities from February 2000 to January 2004.We also use the ROCSAT-Ι data to obtain vertical drifts in three separate 16:00~19:00 local time regions when the geomagnetic Kp index is smaller than 3. The correlation of the post-sunset equatorial irregularity occurrences and the vertical drifts is studied with different of LT regions,geographic longitudes,and seasons. From our study,we found that the vertical drifts increase rapidly at the post-sunset of 18LT~19LT and have a good correlation with vertical drifts. Furthermore,we found the magnetic declination affects the vertical drifts ,and it leads to a better correlation with the irregularity occurrence with the vertical drifts for all seasons.
