由都卜勒風場反演熱動力場的新方法 ——TAMEX IOP#2颮線個案應用分析

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Title:	由都卜勒風場反演熱動力場的新方法 ——TAMEX IOP#2颮線個案應用分析
Authors:	鍾高陞;Gao-Xin Zhung
Contributors:	大氣物理研究所
Keywords:	值函數;線;力擾動場;動力方程式;量方程式;分法;反演
Date:	2001-07-11
Issue Date:	2009-09-22 09:40:52 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究提供一個反演熱動力場的新方法。藉由完整的動量方程式(momentum equation)與熱動力方程式(thermodynamic equation)的結合，利用3D-VAR的變分方式，一旦知道風場在空間上的分佈便能夠反演出壓力與溫度的擾動場。首先，使用數值模擬資料，由一個冷池(cold pool)的中尺度現象來檢驗本方法的可行性。反演所需的輸入場由模式提供。比較模式與反演獲得的壓力與位溫擾動場，在定性及定量上皆有不錯的的結果。接著利用TAMEX計畫在1987年5月17日（IOP#2）觀測到的颮線系統在海上時期進行個案分析。從雙都卜勒雷達合成的三維風場反演壓力與浮力擾動場。由反演的熱動力場可以進一步分析氣壓梯度力、浮力、垂直淨加速度項(dw/dt)在空間上的分佈，探討颮線在對流區與層狀區熱力結構上的不同。而在垂直結構上，比較本反演方式與傳統反演的方法發現，由於後者反演出來的是相對於水平平均的偏差量，在不曉得每一層水平平均值的情形下，解釋垂直結構時可能會發生誤判！最後，藉由可信度參數(reliability parameter)、地面測站的觀測資料、斜溫圖、物理解釋上的合理性以及比較過去數值模擬對颮線的研究等種種間接證據證明，此反演方式可以應用到真實個案，對於瞭解中尺度天氣系統有一定的幫助。 This research presents a new method whereby one can apply the 3D-Var technique to momentum equations and thermodynamic equation to simultaneously retrieve pressure and potential temperature perturbations from Doppler wind measurements. First, a set of artificial data produced by a model-generated cold pool is used to verify this method. The retrieved results are found to be in good agreement with their model-generated counterparts both qualitatively and quantitatively. Then, the newly designed method is utilized to study a squall line system observed during TAMEX IOP#2. The major focus is placed on the structure of the pressure gradient force, buoyancy force, and net acceleration along the vertical direction. The validity of the retrievals is decided based on the reliability parameter, TAMEX surface observation, pre-squall sounding data at Makung , as well as the concept model of a squall line. It is also found in some vertical cross sections that the traditional thermodynamic retrieval algorithm may lead to erroneous interpretation of the thermodynamic field.
Appears in Collections:	[Department of Atmospheric Sciences and Graduate Institute of Atmospheric Physics ] Department of Earth Sciences

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