本篇論文以特高頻(VFH)雷達研究低高度準週期雷達回波（LQP），並以國際地磁參考場(IGRF) 2000模型與電離層探測儀輔助研究。利用雷達干涉法分析追蹤LQP回波塊狀在三維的運動。此法優於從範圍高度時間強度圖 (RTI)探討回波功率隨時間及高度變異現象。利用干涉法 發現在RTI圖上呈現不同條紋的回波塊狀，當隨時間變化追蹤這獨立的回波區域並直到他們從雷達消失前幾乎出現在同一高度。利用這兩種方法比較條紋斜率。證明了利用干涉法與測量RTI 圖上條紋斜率探討LQP回波隨時間的高度變化具有顯著的相關性。但是，標準高度分析法（RTI）並不能提供LQP不規則體正確位置和變異的資訊。干涉法表明產生不規則體回波的正確位置是侷限在高度94-100公里之間，有2-4公里的厚度並呈緩慢下降。出現時間週期約幾十秒鐘至最大值三分鐘。因為中壢是接近赤道區域，證明LQP也發生在溫帶區域。
電離層探測儀之虛高(97~100公里)，約略在干涉法所得高度之上部。foEs 與fbEs的時間變化與高度之遞減變化時間有對應關係，Δf並無明顯變化。利用IGRF 2000模型進行方向靈敏度的分析中，發現回波功率與範圍高度關係不明顯。但是，回波功率與對地球磁場的垂直角度偏差有一明顯負關係存在。

This paper presents observations of Low-altitude QP. Our interferometer analysis allows investigating the motion of the LQP echo patches in three-dimensions. This method is superior to just evaluating the variations of the echo power as function of range and time in the standard RTI plots. By applying this method, we show that the echo patches in different striations remain at almost the same altitude when we trace the isolated echoing regions until they disappear from the radar view. We further compare the rate of change of the range (range rate dR/dt) by two techniques. We prove that the changes in range as function of time, deduced from the interferometer technique are significantly correlated with those of the standard range rate analysis. However, the standard range rate analysis does not provide information about the correct location and the variation of the LQP irregularities. We study and find correct locations of these echoes creating irregularities, which are confined to the height range between 90 km and 100 km, have a thickness of 2-4 km and are only slowly descending in altitude. They occur with periods of some tens of seconds to maximum three minutes. Since Chung-Li is close to the equatorial region, we prove that these LQP occur in this temperate region as well.
Altitude distributions of the QP echoes are well correlated with the h’Es by the Ionosonde. From the IGRF 2000 model, there are well correlation between the angle offset perpendicularity of the magnetic line and the echo power. In comparison, we find that there exists negative correlation between them more offset gets lower echo power.

Bernhardt, P.A.,The modulation of sporadic-E layers by Kelvin-Helmholtz billows in the neutral atmosphere, J. Atmos. Sol-Terr. Phys., 64, 1487-1504, 2002.
Buneman, O., Excitation of field aligned sound waves by electron streams, Physical Review Letters, 10, 285, 1963.
Chau, J.L., and R.F. Woodman , Low-latitude quasiperiodic echoes observed with the Piura VHF radar in the E region, Geophys. Res. Lett., 26, 2167-2170, 1999.
Chen, C.L., C.J.Pan, J.Roettger, and V.K.Anandan , Three-dimensional tracking of mid-latitude quasi-periodic E-region echoes observed with the Chung-Li VHF radar, Ann. Geophy., 23, 393-400, 2005.
Choudhary, R.K.,and K.K. Mahajan , Tropical E region field-aligned irregularities: Simultaneous observations of continuous and QP echoes, J. Geophys. Res., 104, 2613-2619, 1999.
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 Sci., 32(2), 817-832, 1997.
Farley, D.T., A plasma instability resulting in Field-aligned irregularities in the ionosphere, J. Geophys. Res., 68, 6083-6097, 1963.
Farley, D.T., H.M. Ierkic, and B.G. Fejer , Radar interferometry: a new technique for studying plasma turbulence in the ionosphere, J. Geophys. Res., 86, 1467-1472, 1981.
Fukao, S., M. Yamamoto, R.T. Tsunoda, H. Hayakawa, and T. Mukai , The SEEK (Sporadic-E Experiment over Kyushu)campaign, Geophys. Res. Lett., 25, 1761-1764, 1998.
Haldoupis, C., G.C. Hussey, A. Bourdillon, and J. Delloue , Azimuth-Time-Intensity striations of quasiperiodic radar echoes from the mid-latitude E-region ionosphere, Geophys. Res. Lett., 28, 1933-1936, 2001.
Haldoupis, C., A. Bourdillon, A. Kamburelis, G.C. Hussey, and J.A. Koehler : 50 MHz continuous wave interferometer observations of the unstable mid-latitude E-region ionosphere, Ann. Geophysicae, 21, 1589-1600, 2003.
Hysell, D.L., and J.D. Burcham, HF radar observations of quasiperiodic E layer echoes over North America, J. Geophys. Res., 104, 4361-4371, 1999.
Hysell, D.L., and J.D. Burcham, The 30-MHz radar interferometer studies of midlatitude E region irregularities, J. Geophys. Res.,105, 12797-12812, 2000.
Hysell, D.L., M. Yamamoto, and S. Fukao, Imaging radar observations and theory of type I and type II quasiperiodic echoes, J. Geophys. Res., 107, doi10.1029/2002JA009292, 2002.
Kagan, M. L., M. C. Kelley , A wind-driven gradient drift mechanism for mid-latitude E-region ionospheric irregularities, Geophys. Res. Lett., 25, 4141, 1998.
Kelley, M. C., The Earth’s Ionosphere, Academic Press, London, 1989.
Kelly, M.C., D. Riggin, R.F. Pfaff, W.E. Swartz, J.F. Providakes, and C.S. Huang, Large amplitude quasi periodic fluctuations associated with a midlatitude sporadic E layer, J. Atmos. Terr. Phys., 57, 1165-1178, 1995.
Larsen, M.F., A shear instability seeding mechanism for quasiperiodic radar echoes, J. Geophys. Res., 105(A11), 24931-24940, 2000.
Lee, C. C., J. Y. Liu, and C. J. Pan, The heights of sporadic-E layer simultaneously observed by the VHF and ionosondes in Chung-Li, Geophys. Res. Lett., 27, 641, 2000.
Mathews, J.D. , Sporadic E: current views and recent progress, J. Atmos. Terr. Phys., 60, 413-435, 1998.
Pan, C.J. and M.F. Larsen , Observations of QP radar echo structure consistent with neutral wind shear control of the initiation mechanism, Geophys. Res. Lett., 27(6), 867-870, 2000.
Pan, C.J., and P.B. Rao , Low altitude quasi-periodic radar echoes observed by the Gadanki VHF radar, Geophys. Res. Lett., 29(11), doi:10.1029/2001GL014331, 2002.
Pan, C.J., C.H. Liu, J. Röttger, and S.Y. Su , A three dimensional study of E region irregularity patches in the equatorial anomaly region using the Chung-Li VHF radar, Geophys. Res. Lett., 21(17), 1763-1766, 1994.
Pan, C.J., and R.T. Tsunoda , Quasi-periodic echoes observed with the Chung-Li VHF radar during the SEEK campaign, Geophys. Res. Lett., 25, 1809-1812, 1998.
Pan, C.J., and R.T. Tsunoda , Semidiurnal behavior of quasi-periodic echoes in the mid-latitudes Es region observed with the Chung-Li VHF radar, Geophys. Res. Lett.,26, 2621-2624, 1999.
Pan, C.J., and P.B. Rao , Morphology of the field-aligned E-layer irregularities observed by the Gadanki VHF radar, Proceedings of the Tenth Workshop on Technical and Scientific Aspects of MST Radar,114-117, 2003.
Patra, A.K., S. Sripathi, V.S. Kumar, and P.B. Rao , Evidence of kilometer-scale waves in the lower E-region from high resolution VHF radar observations over Gadanki, Geophys. Res. Lett., 29(10), doi:10.1029/2001GL013340, 2002.
Ratcliffe, J. A., An Introduction to the Ionosphere and Magnetosphere, Cambridge, UK, 1972.
Rao, P.B., M. Yamamoto, A. Uchida, I. Hassenpflug, and S. Fukao , MU radar observations of kilometer-scale waves in the midlatitude lower E-region, Geophys. Res. Lett., 27(22), 3667-3670, 2000.
Rogister, A. and N. D’Angelo , Type II irregularities in the equatorial electrojet, J. Geophys. Res., 75, 3879, 1970.
Sripathi, S., A.K. Patra, V. Sivakumar, and P.B. Rao , Shear instability as a source of the daytime quasi-periodic radar echoes observed by the Gadanki VHF radar, Geophys. Res. Lett., 30(22), 2149, doi:10.1029/2003GL017544, 2003.
Sudan, R. N., J. Akinrimisi, and D. T. Farley , Generation of small-scale irregularities in the equatorial Electrojet, J. Geophys. Res., 78, 240, 1973.
Tsunoda, R.T., S. Fukao, and M. Yamamoto , On the origin of quasi-periodic radar backscatter from midlatitude sporadic E, Radio Sci., 29, 349-365, 1994.
Tsunoda, R.T., J.J. Buoncore, A. Saito, T. Kishimoto, S. Fukao, and M. Yamamoto , First observations of quasi-periodic radar echoes from Stanford, California, Geophys. Res. Lett., 26, 995-998, 1999.
Urbina, J., E. Kudeki, S.J. Franke, S. Gonzalez, Q. Zhou, and S.C. Collins , 50 MHz radar observations of mid-latitude E-region irregularities at Camp Santiago, Puerto Rico, Geophys. Res. Lett., 27(18), 2853-2856, 2000.
Urbina, J., E. Kudeki, S.J. Franke, and Q. Zhou , Analysis of a mid-latitude E-region LQP event observed during the Coqui 2 Campaign, Geophys. Res. Lett., 31, No. 14, L14805, doi: 10.1029/2004GL020031, 2004.
Wakai, N., H. Ohyama, and T. Koizumi, Manual of ionogram scaling, third version, Radio Research Laboratory, Ministry of Posts and telecommunications, Japan, 1987.
Wang, C.Y. and Y.H. Chu , Interferometry investigations of blob-like sporadic E plasma irregularity using the Chung-Li VHF radar, J. Atmos. Solar-Terr. Phys.,63,123-133, 2001.
Woodman, R.T., M. Yamamoto, and S. Fukao , Gravity wave modulation of gradient drift instabilities in mid-latitude sporadic E irregularities, Geophys. Res. Lett., 18, 1197-1200, 1991.
Yamamoto, M., S. Fukao, R.F. Woodman, T. Ogawa, T. Tsuda, and S. Kato , Midlatitude E region field-aligned irregularities observed with the MU radar, J. Geophys. Res.,96(A6), 15943-15949, 1991.
Yamamoto, M., N. Komoda, S. Fukao, R.T. Tsunoda, and T. Ogawa , Spatial structure of the E-region field aligned irregularities revealed by the MU radar, Radio Sci., 29(1), 337-348, 1994.
Yamamoto, M., T. Ono, H. Oya, R.T. Tsunoda, M.F. Larsen, S. Fukao, and M. Yamamoto , Structure in sporadic-E observed with an impedance probe during the SEEK campaign: Comparisons with neutral-wind and radar-echo observations, Geophys. Res. Lett., 25, 1781-1784, 1998.
陳益華，中壢特高頻雷達電離層觀測與研究，博士論文，國立中央大學大氣物理研究所，1993。