李天浩2006-07-252018-07-092006-07-252018-07-092005http://ntur.lib.ntu.edu.tw//handle/246246/2915在多雷達觀測區域中進行風場反演，可 以獲得多個都卜勒風限制式，但無法取得所 有點的三維正交風速分量觀測值。為了彌補 觀測資訊的不足，可以使用連續方程式或其 他限制條件結合多個都卜勒風限制式一起聯 立求解；或是假設風場具有某種特性下，採 用迴歸方程式表現風的三維分量，以減少未 知數的數量。Scialom 和 Lemaitre（1990） 提出三維解析風場的概念，將其代入泛函求 極小值的問題中，使原本的變分問題轉換為 待定係數問題，利用最小誤差平方和法即可 求解風場（MANDOP 分析），本研究將其延 伸應用到求解颱風風場，希望藉由依環流特 性所選擇的圓柱座標系統來提升風場反演的 準確度。 選擇颱風風場函數時，採用以颱風中心 為中心軸的圓柱座標系統，並假設風場解析 函數為三個多項式函數的乘積，在徑向方向 使用冪次(Power)多項式展開，切向方向使用 傅利業(Fourier)多項式展開，而垂向方向則使 用勒尖德(Lengendre)多項式展開。在限制條 件方面，除了使用都卜勒風限制式與連續方 程式限制條件外，還包括近地面、近對流層 頂和颱風中心等三處垂直風為零的邊界條 件。 在模擬實際應用時，除了使用均勻流與 渦旋流進行測試外，並採用洪景山博士以 MM5 模式模擬賀伯颱風的三維風場輸出資 料，作為真實颱風的風場。在探討風場反演 的效果時，假設有二到三個雷達，分別設在 不同位置，模擬各雷達的都卜勒風速觀測資 料，接著利用研擬的方法反演風場，比較反 演風場與真實風場在不同條件下，評估風場 反演的效果與權重因子的影響。Many Doppler wind constrains can be obtained in multiple radars observation area, but the three orthogonal wind components can not be acquired in full domain. In order to compensate the lost information of observation, continuity equation or other constrains combined with many Doppler wind constrains are used. Besides, under the assumption of certain characters of the wind field, regression equations can be applied for representing the wind components to reduce the unknown numbers. Scialom and Lemaitre (1990) addressed the concept of a three dimensional analytical wind field and brought it into the cost function, and thus converted the variational problem into the regression problem which can be solved by the least square error method. The present research is devoted to the application of MANDOP analysis in retrieving the typhoon wind field and introducing the cylinder coordinates to improve the accuracy of the result. The present paper adopts the cylinder coordinates in which the center axis is typhoon center and assumes that the analytical wind components, with respect to each coordinate, may be written as a product of three functions of each coordinate. The base functions are power series in radial, Fourier series in tangential and Lengendre series in vertical direction. In the respect of constrains, except for using Doppler wind and continuity constrains, the boundary condition at ground, top of troposphere and typhoon center are included. Besides using uniform flow and vortex for testing, the simulated typhoon Herb data, produced from MM5 model, are used as the real typhoon wind field. Doppler wind observations are simulated from two to three radars which are at different places. The wind retrieval method above is used to evaluate the results and the affects by comparing the retrieval wind with the true wind under different conditions.application/pdf1090249 bytesapplication/pdfzh-TW國立臺灣大學土木工程學系暨研究所都卜勒雷達三維風場反演Doppler radar3D wind retrievalMANDOPreporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/2915/1/932625Z002012.pdf