本篇論文分析印度Gadanki MST雷達、中壢VHF雷達與日本FAR雷達對於電離層E層之觀測資料，並將中壢VHF雷達和日本FAR雷達之觀測結果與中壢以及Yamagawa電離層探測儀的資料做一比對，以尋找不同地區E層回波的特性。研究結果顯示： 1.在近磁赤道地區，Gadanki MST雷達夜晚的E層回波在高度90到105公里與105到120 公里兩個區域較常出現；白天則在高度100公里附近的區域較常出現。而且在100公里附近有觀測到所謂的較低高度之QP（Low altitude QP, LQP）回波，而此類回波為經常性出現的回波。 2.在中緯度地區，中壢VHF雷達的觀測結果顯示出現週期、徑向速度以及斜紋斜率（Range Rate）存在特定關係。至於日本FAR雷達的觀測結果，是以負斜率的QP（Negative QP, NQP）回波為較常出現的回波型態。 3.比較FAR雷達與Yamagawa電離層探測儀之共同觀測結果顯示，當回波型態為NQP時，雷達回波的出現時間與（foEs - fbEs）增大的時間兩者有一差距。就回波的出現高度來看，兩者觀測所得之回波高度有良好的相關性。 The Field Aligned Irregularities (FAI) in the ionosphere E region have been observed by the radar for decades. In this study, we analyze the data obtained from three radars, namely the Gadanki MST radar, the Chung-Li VHF radar and the FAR (Frequency-Agile Radar). The results show that the echo signals detected by Gadanki radar are frequently appeared in the two ranges of height: 90-105 km and 105-120 km at the nighttime and at about 100 km in the daytime. LQP (Low altitude Quasi-Periodic radar echoes) echoes have also been detected by Gadanki radar at around 100 km frequently. By using the Chung-Li VHF radar, we find the correlations among the periodicity, radial velocity, and range rate of the QP echoes. The periodicity and range rate are lager when radial velocities are more broadly spread, and vice versa. However, we also find that the periodicity decreases with increasing range rate. For the FAR results, only the appearance periods of the QP echoes with negative range rate slope may characterize a time delay with those of the enhancement of the gradient of the electron observed by the Ionosonde. We also notice that the altitude distributions of the QP echoes are well correlated with the h'Es.
