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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/4937


    Title: 利用單都卜勒雷達反演三維風場之研究─以數值模式資料驗證
    Authors: 章鶴群;Ho-Chin Chang
    Contributors: 大氣物理研究所
    Keywords: 雷達;反演
    Date: 2003-06-23
    Issue Date: 2009-09-22 09:41:34 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 摘要 移動座標法是單都卜勒雷達反演風場的一種方法。為了減少因為雷達不連續觀測所造成計算上的誤差,所以在反演的過程中採用移動的參考座標。此方法主要是利用雷達觀測到的回波、徑向風(Vr),配合著若干數學上的約束條件,以變分法解出一個風場,能夠最滿足這些約束條件。傳統上,此方法是用於反演低層的水平風場(u、v),而移動座標的移速是指系統水平移速(U、V)。 本研究改變了移動座標為「水平」的傳統,將反演的區域從二維平面推廣到三維的空間中,嘗試同時反演三個未知的變數(u、v、w)。為了要驗証此方法的可行性,先採用簡單的平流模式初步証實是可行的,此平流模式模擬回波隨著風場的平流效應而移動,風場並不隨著時間改變。 其次,再利用RAMS model產生的理想資料做測試,RAMS Model所模擬的風場是根據流體力學方程組預報的,因此會隨時間改變。測試的結果顯示,這樣在三維空間中的反演是可行的,並且對於垂直速度反演的相當好,相關係數均能夠達到0.9以上。而反演的區域與雷達距離的遠近、掃瞄的策略不同以及系統是否有移速,並沒有太大的影響,可能是因為本實驗中使用滿足流體力學的方程式、回波保守、且無觀測誤差的理想數值模式的資料進行反演。 ABTRACT The moving frame of reference technique is a method that retrieves wind field from single-Doppler radar observed radial wind and reflectivity. In this paper, this technique is developed to retrieve three dimension wind field. The performance of this method is explored using idealized data sets generated from a numerical model. Several factors which may affect retrieval results have been tested. These factors include: the distance between the radar site to the area of interest; the scanning strategy; as well as the moving speed of the weather system. The results show that three-dimensional wind field can be retrieved accurately from single-Doppler radar observed radial wind and reflectivity simulated by numerical model. Especially, there is high correlation between the retrieved vertical flow structure and its true counterpart. This result is particularly encouraging
    Appears in Collections:[大氣物理研究所 ] 博碩士論文

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