大氣風場與降水探測技術的建立與研究; Observation technique development on atmosphere wind field and preciepitation

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题名:	大氣風場與降水探測技術的建立與研究;Observation technique development on atmosphere wind field and preciepitation
作者:	蘇清論;Ching-Lun Su
贡献者:	太空科學研究所
关键词:	三甲基鋁;風場;渦漩;波束半功率波束寬;冰晶粒子;過冷水;雷達;降水;Radar;precipitation;TMA;wind field;vortex;HPBW;ice crystal;super cool water
日期:	2004-12-23
上传时间:	2009-09-22 09:45:10 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	地球包覆在大氣層中，大氣的各種變化與結構特性，除了影響生存環境，也保護著所有生物。從古至今，國內外學者對於大氣環境的種種研究從未間斷，本人亦參與了低層大氣的研究與高層大氣約80~150km左右中性風的研究。首先，利用雷達脈波長度2μs和脈波長度4μs的不同解析度特性，進行降水觀測，證實在較低層的區域，降水粒子的分布並未如氣象觀念中傳統的假設---均勻分布在雷達體積中，而是呈現不均勻分布情形。其次，分別假設雨滴分布函數為指數分布函數形式N(D)=Noexp(-δD)與Gamma分布函數形式N(D)=NoD^(-μ)exp(-δD)推導出以前學者未導出的power-law關係中的α和β值。接著，利用中壢VHF雷達同時發射垂直波束與傾斜波束，配合天線場型模擬分析軟體，在降水環境下，利用降水回波特性，確認中壢VHF雷達傾斜波束與垂直波束的方向靈敏性關係；並利用固態冰晶與液態水粒子產生的雷達回波功率差異性，分辨出單一物態如固態冰晶粒子、液態降水粒子的高度範圍；且證實0℃等溫線以上含有液態水或過冷水的區域範圍，應該在1公里高度範圍之內；並利用雷達波束方向靈敏性的理論，發現雷達波束半功率波束寬與天線增益，會隨著環境而改變，尤其在降水環境中，影響最大。最後，TMA實驗部分，建立一套TMA地面高解析度數位照相技術；利用數位底片高解析度的特性，使用球面三角與平面三角結合定位法，以較以更高的精度定位出TMA尾跡的位置。另外，TMA實驗同時觀測到渦漩亂流結構，經詳細定位出其中心位置，可計算出渦漩亂流結構的南北、東西分布尺度與高度分布厚度分別約為5公里、1.3公里和2公里厚。TMA尾跡定位後，得以計算出台灣上空中氣層與低熱氣層中性風場，成功地說明TMA環型尾跡成因。 The earth is surrounded with atmosphere layer. The variation and structure of the atmosphere not only affects our living environment but also protects all creatures on the earth. From ancient times to the present, the research of atmosphere has been conducted by Scholars around the world. My major research is on the study of the neutral wind around 80~150km height and the study of lower atmosphere phenomena. At first, the precipitation observations were conducted with different resolutions at 2μs and 4μs pulse width. The precipitation particles were found to reveal non-uniform distribution that is not consistent with the traditional assumption of uniform distribution in the radar volume. The rain drops distribution can be described by exponential type equation, N(D)=Noexp(-δD), or by the Gamma equation, N(D)=NoD^(-μ)exp(-δD) , The important coefficients ,αandβin the power-law relationship, it is successfully deduced for the first time. While observing by the vertical beam and 17 degree tilt beam at the same time, the aspect sensitivity is verified through the precipitation echo power analysis. The antenna pattern is carefully analyzed and calibrated in order to prove these important characteristics. The height distribution of the solid ice crystal and the liquid water particle can be differentiated by the radar echo return power from each other. It was proved that the extend range of liquid water and super cool water should be confined within one kilometer. The half power beam width and the gain of the antenna change with environment, especially under precipitation. The wind field deduction around 80~150km height is based on the TMA experiment results. To conduct the TMA experiment, a very high resolution digital camera system was set up. High accuracy of image position determination method was developed by using spherical trigonometry and surface trigonometry techniques. The turbulence vortex structure was detected. The distribution scale from north to south, east to west was found to be 5km and 1.3km and the thickness is 2 km. The neutral wind can be deduced after the TMA trail location has been precisely determined. The reason of ring type trail formation can be explained successfully through this analysis.
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