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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5145

    Title: 中壢上空低高度準週期回波之探討;Investigations of LQP echoes over Chung-Li
    Authors: 陳中亮;Chung-Liang Chen
    Contributors: 太空科學研究所
    Keywords: 散塊E層;電離層;場沿不規則體;Ionosphere;FAI;Es
    Date: 2005-06-03
    Issue Date: 2009-09-22 09:45:54 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 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.
    Appears in Collections:[太空科學研究所 ] 博碩士論文

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