電離層中的散塊E層(Sporadic E)簡稱Es，高度大約在90~120公里間，成分除了一些分子性離子外，金屬性離子佔絕大部分。
中緯度Es層的QP( Qusai -Periodic)現象首度被Yamamoto在1991年利用MU雷達觀測到，其後台灣Chung-Li雷達也有接收到QP的回波，但是對於QP的發生卻有各門各派的解釋方法。本篇論文的資料是在1997年8月7日晚上及8月8日凌晨中壢特高頻雷達觀測到的電離層Es層散塊回波，從RTI圖上發現訊號存有準週期回波的特徵，而頻譜圖呈現是屬於型態二梯度飄移不穩定所造成的二次回波。利用雷達干涉法我們可分析不規則體的飄移情形，並在比較各個QP理論後對台灣地區中緯度QP現象的發生嘗試找出合理的解釋。

Sporadic E (Es) layers are ionization enhancements in the E region at altitude between 90 and 120 km. The density can be up to an order of magnitude greater than that in the background and the major species in the layer are metallic.
High-resolution observations of quasi-periodic (QP) structures of the midlatitude E region irregularities made with the MU radar were presented in 1991. The structures were found to display striations with periods close to the Brunt Vaisala period. After then, the Chung-Li radar observed the same phenomenon, too.
The physical mechanisms proposed for the generation of QP echoes are associated with gravity wave and wind shear. In this study we present an optimum postulate for the QP echoes observed at the Chung-Li VHF radar.

Tom, B., Atmospheric Waves, Halsted Press, New York, 1974.
Chu, Y. H., and C. Y. Wang, Interferometry observations of three-dimensional spatial structures of sporadic E irregularities using the Chung-Li VHF radar, Radio Science, 32, 817, 1997.
Farley, D. T., H. M. Ierkic, and B. G. Fejer, Radar interferometry: A vew technique for studying plasma turbulence in ionosphere, Journal of Geophysical Research, 86, 1467, 1981.
Fukao, S., M. Yamamoto, R. T. Tsunada, H. Hayakawa, and T. Mukai, The SEEK(sporadic-E experiment over Kyushu) campaign, Geophysical Research Letters, 25, 1761, 1998.
Henry Rishbeth, O. K. Garriott, Introduction To Ionospheric Physics, International Geophysical Series, Academic Press, New York, 1969.
Huang, C. M., E. Kudeki, S. J. Franke, C. H. Liu, and J. Rottger, Brightness distribution of midlatitude E region echoes detected at the Chung-Li VHF radar, Journal of Geophysical Research, 100, 14703, 1995.
Julio Urbina, E. Kudeki, S. J. Franke, 50MHz radar observations of mid-latitude E-region irregularities at Camp Santiago, Puerto Rico, Geophysical Research Letters, 27, 2853, 2000.
Kagan, M. L., M. C. Kelley, A wind-driven gradient drift mechanism for mid-latitude E-region ionospheric irregularities, Geophysical Research Letters, 25, 4141, 1998.
Kelley, M. C., The Earth’s Ionosphere: Plasma Physics and Electrodynamics, International Geophysical Series, Academic Press, New York, 1989.
Larsen, M. F., A shear instability seeding mechanism for quasiperiodic radar echoes, Journal of Geophysical Research, 105, 24931, 2000.
Pan, C. J., R. T. Tsunoda, Quasi-periodic echoes observed with the Chung-Li radar during the SEEK campaign, Geophysical Research Letters, 25, 1809, 1998.
Riggin, D., W. E Swartz, J. Providakes, and D. T. Farley, Radar studies of long-waves associated with mid-latitude sporadic E layers, Journal of Geophysical Research, 91, 8011, 1986.
Sudan, R. N., J. Akinrimisi, and D. T. Farley, Generation of small-scale irregularities in the equatorial Electrojet, Journal of Geophysical Research, 78, 240, 1973.
Tsunoda, R. T., S. Fukao, and M. Yamamoto, On the origin of quasi-periodic radar backscatter from midlatitude sporadic E, Radio Science, 29, 349, 1994.
Whitehead, J. D., The formation of sporadic-e layer in the temperate zones, J. Atmos. Terr. Phys., 20, 40, 1961.
Woodman, R. F., M. Yamamoto, and S. Fukao, Gravity wave modulation of gradient drift instabilities in mid-latitude sporadic E irregularities, Geophysical Research Letters, 18, 1197, 1991.
Yamamoto, M., S. Fukao, R. F. Woodman, T. Ogawa, T. Tsuda, and S. Kato, Mid-latitude E region field-aligned irregularities observed with the MU radar, Journal of Geophysical Research, 96, 15943, 1991.
Yokoyama, T., M. Yamamoto, and S. Fukao, Computer simulation of polarization electric fields as a source of midlatitude field-aligned irregularities, Journal of Geophysical Research, 108, 1054, 2003.
楊國峰，電離層散塊E層型態二不規則體之研究，碩士論文，國立中央大學太空科學研究所，2001。
陳建智，梯度飄移不規則體之準週期性移動的研究，碩士論文，國立中央大學太空科學研究所，2000。