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研究生:李俊彥
研究生(外文):Chun-Yen Lee
論文名稱:莫拉克颱風雨帶內對流胞擾動氣壓分布之探討
論文名稱(外文):Perturbation Pressure in Cells of Rainbands Associated With Typhoon Morakot
指導教授:郭鴻基郭鴻基引用關係
口試委員:王重傑李清勝楊明仁陳台琦
口試日期:2013-07-05
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:大氣科學研究所
學門:自然科學學門
學類:大氣科學學類
論文種類:學術論文
論文出版年:2013
畢業學年度:101
語文別:中文
論文頁數:141
中文關鍵詞:低層噴流垂直風切擾動氣壓浮力垂直擾動氣壓梯度力
外文關鍵詞:low level jetvertical wind shearperturbation pressurebuoyancyvertical perturbation pressure gradient
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本論文研究颱風環境中對流胞與低層噴流的交互作用,莫拉克颱風(2009) 的觀測中顯示,東西走向的雨帶座落於臺灣海峽颱風環流與西南季風的氣流交會所產生的輻合帶中,雨帶由多個向東移動的對流胞組成,並伴隨30 m/s的低層西風噴流。成熟的對流胞西側常有新的對流發展,對流胞東移的速度一般而言比起低層噴流的速度更慢。我們使用空間解析度1公里的雲解析風暴(CReSS)模式模擬、分析莫拉克颱風雨帶內的對流胞,我們的研究假設為,當低層噴流伴隨的垂直風切與對流胞中垂直速度具有的水平差異交互作用時,可以在對流胞的上風處產生顯著的垂直氣壓梯度力,莫拉克颱風雨帶內對流胞西側的垂直氣壓梯度力有可能強化原本的對流胞。
我們使用數值模式資料分別求出浮力擾動氣壓與動力擾動氣壓的大小,並且可進一步的將動力擾動氣壓分離為線性與非線性項的貢獻,線性項包含低層噴流形成的垂直風切與在對流中的上衝流產生的水平差異貢獻,非線性項則來自對流胞本身。透過氣壓的診斷結果,線性的作用對動力擾動氣壓的貢獻最為重要,低層噴流與對流的交互作用,將分別在對流胞西側的低層與高層形成相對擾動高壓與低壓,以及正的垂直擾動氣壓梯度力。成熟的對流胞中除了浮力以外,動力垂直擾動氣壓梯度力也在對流胞的西側貢獻正的垂直加速度。
我們的分析強調颱風環境中低層噴流的重要性,當低層噴流與現有的對流胞交互作用時,對流胞的西側可能會在上風處產生顯著的垂直動力擾動氣壓梯度力,此作用力可能會在颱風雨帶內強化原本的對流胞。


This thesis studies the convective cell interaction with the low-level jet in the typhoon (TY) environment. Observations of TY Morakot (2009) indicate that the east-west oriented rainband in the Taiwan Strait is in the convergent zone caused by the interaction of the TY circulation and the southwesterly monsoon flow. The rainband is with low-level westerly jet of 30 m/s and composed of many eastward moving convective cells. The new convection often developed to the west of the mature cells and the eastward speed of the convective cell in general is slower than the low-level jet speed. We use 1-km resolution Cloud Resolving Storm Simulator (CReSS) model to simulate and to analyze the convective cells in rainbands associated with TY Morakot. Our hypothesis that the vertical wind shear associated with the low level jet, when interacted with the horizontal vertical wind variation in the presence of the convection, can generate significant vertical pressure gradient force on the upwind side of the convective cell. The vertical pressure gradient force to the west of the convective cells may strengthen the convective cell in the TY Morakot rainband.
With the numerical model data, we solve for the buoyancy pressure perturbation and dynamic pressure perturbation. The dynamic pressure perturbation can be further separated into the linear and non-linear contributions. The linear term mainly involves the product of the vertical wind shear from the low-level jet and the horizontal variation of the convective updraft and the nonlinear terms are from convective cells. Our pressure diagnosis suggests that the linear contribution is the most important in the dynamic pressure perturbation. The interaction of the low-level jet with convection will produce relative high (low) dynamic pressure perturbation in the lower (upper) level and positive vertical perturbation pressure gradient to the west of the convective cells. Together with the buoyancy, the dynamics vertical pressure perturbation gradient force also contributes to the positive vertical acceleration to the west of the mature convective cells.
Our analysis highlights the importance of the low-level jet in TY environment when interact with existing convective cells may produce significant dynamic vertical pressure perturbation gradient to the upwind side. The dynamic vertical pressure gradient force may strengthen the convective cells in the TY rainband.


第一章 前言 ......................................... 1
1.1 研究背景 ...................................... 1
1.2 文獻回顧 ...................................... 2
1.3 研究動機 ...................................... 5
第二章 資料說明 ...................................... 7
2.1 資料來源 ...................................... 7
2.2 模擬結果與回波之比較 .......................... 8
第三章 模式資料水平與東西剖面之分析 ................... 9
3.1 雨帶之選擇 ..................................... 9
3.2 求取擾動場 .................................... 9
3.3 東西剖面與水平面之分析 ......................... 11
3.3.1 q_3與溫度分析 ........................... 12
3.3.2 水平輻合輻散與東西風分析................. 12
3.3.3 垂直風切分析............................. 14
第四章 垂直動量方程式分析 ............................ 17
4.1 垂直動量方程式與各項分析 ...................... 17
4.2 時序圖分析與垂直加速尺度分析 .................. 21
4.2.1 對流胞選擇............................... 21
4.2.2 時序圖分析............................... 22
4.2.3 對流胞垂直加速尺度分析................... 23
第五章 擾動氣壓分離與對流胞內部分析.................... 25
5.1 分離擾動氣壓 .................................. 25
5.2 雨帶Laplacian擾動氣壓分布探討................... 26
5.3 對流胞Laplacian擾動氣壓分布探討................. 27
5.3.1 Laplcian動力擾動氣壓各項大小比較 ............... 27
5.3.2 對流胞東西剖面探討 ....................... 28
5.3.3 對流胞南北剖面探討 ......................... 34
5.3.4 背景場、擾動場垂直風切對動力擾動氣壓影響 .....37
第六章 結論 ............................................42
參考文獻 ............................................... 45
附錄 鬆弛法計算過程與結果.............................. 47
附圖表.................................................. 50


唐玉霜,2010: 2009 莫拉克颱風雷達觀測中尺度雨帶特性研究。國立中央大學大氣物理所碩士論文,70頁。

陳台琦,魏志憲,林沛練,廖宇慶,唐玉霜,張偉裕,周鑑本,紀博庭,林忠義,2010:莫拉克颱風雷達觀測中尺度雨帶特徵。莫拉克颱風科學報告,53-81。

蔡宜君,2012: 使用偏極化/多都卜勒雷達資料研究莫拉克颱風(2009)地形降雨特性。國立中央大學大氣物理所碩士論文,83頁。

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