臺灣博碩士論文加值系統

利用單都卜勒氣象雷達資料來研究伴隨鋒面的中尺度對流系統與低層噴流之相互關係，就日常天氣預報作業而言，是有其絕對的必要性。本研究的目的，就是利用中正機場單一都卜勒氣象雷達資料，分析1987年6月8日與1997年6月10日發生在台灣中北部海面中尺度對流系統的演變過程，探討低層噴流在激發與維持鋒面中尺度對流系統的可能機制。
兩個案的綜觀環境顯示在對流系統發展之前，低層噴流已存在於廣東沿海至台灣一帶，鋒面逐漸通過台灣北部，然而板橋測站的探空資料顯示，兩者的大氣環境在提供氣塊舉升的能量上有極大的差異，在1987年6月8日0000 UTC之對流可用位能值僅為2.9 m2/s2，且在900 hPa以下存在逆溫現象。而第二個案在1997年6月10日1200 UTC時沒有低層逆溫，對流可用位能值卻可達到2375.4 m2/s2。
由雷達資料對降水回波中心在水平與垂直結構的細微分析中，可知兩個案均存在深（發展高度大於10公里）與淺（發展高度介於5至9公里）的對流系統。綜合而言有以下的發現：大氣熱力提供對流發展的能量並非為決定對流發展深淺的主要因素，低層噴流的動力機制在對流的生成與發展扮演舉足輕重的角色。而低層噴流在激發與維持對流系統之影響，可歸納出四種動力作用：低層噴流在鋒面前導線之輻合激發淺對流系統發展；低層噴流與西來氣流交互作用，可激發對流系統；低層噴流左側之輻合維持深對流系統的發展；低層噴流與陣風鋒面形成之局部輻合僅可維持對流系統短暫時間的發展。

ABSTRACT
It is quite necessary for daily weather forecasting to realize the relationship between frontal mesoscale convective systems（MCSs） and low-level jet （LLJ）. Two cases（8 June 1987 and 10 June 1997）, based upon the observations of the ground-based single doppler radar, were investigated in this research in order to find out the appropriate physical mechanisms of the triggering and maintenance of MCSs by the LLJ.
From the synoptic scale point of view, LLJ had been located at the south China and Taiwan areas before the MCSs developed while the Mei-yu front accompanied with MCSs was approaching and passing the northern Taiwan. The Pao-chiao station sounding profiles showed that the energies supporting the parcel lifting in the atmosphere for these two cases were quite different. There was an inversion layer below 900 hPa, and the magnitude of convective available potential energy was only 2.9 m2/s2 at 0000 UTC of 8 June 1987. But the magnitude of convective available potential energy was 2375.4 m2/s2 at 1200 UTC of 10 June 1997 in the second case.
According to the horizontal and vertical structures of MCSs after the detailed analysis of radar data, it was recognized that deep (larger than 10 km in altitude) and shallow (between 5 and 9 km in altitude) convections were present in both cases. The significant findings in the study are: The atmospheric thermodynamic condition is not a key factor for the development of convection. The dynamic mechanisms play important roles for the initiation and development of convection. Furthermore, there are four flow patterns delineating the triggering and maintenance of convective systems: The convergence initiated by LLJ over frontal leading edge is responsible for triggering the development of shallow convective systems; The confluence of southwesterly LLJ and westerly flow usually starts the convective systems; The cyclonic convergence on the left flank of LLJ maintain the development of deep convection systems; The local convergence interacted between the LLJ and gust frontal system can only support the existence of convective systems over a short period.

1. 前言1
1.1. 論文回顧1
1.2. 研究動機及目的3
2. 資料來源與分析方法5
2.1. 資料來源5
2.2. 雷達資料處理方法5
2.3. 速度方位顯示6
3. 綜觀天氣概述8
3.1. 傳統天氣資料分析8
3.1.1. 1987年6月8日 個案8
3.1.2. 1997年6月10日個案15
3.2 衛星雲圖分析19
3.2.1. 1987年6月8日 個案19
3.2.2. 1997年6月10日 個案22
3.3. 小結22
4. 降水回波演變與徑向風場特徵之分析24
4.1. 降水回波演變24
4.1.1. 1987年6月8日 個案24
4.1.2. 1997年6月10日 個案25
4.2. 徑向風場分析31
4.2.1. 1987年6月8日 個案31
4.2.2. 1997年6月10日 個案34
5. 低層噴流與中尺度對流系統之運動特性42
5.1. 低層噴流與中尺對流系統之特徵分析42
5.2. VAD 風場與低層噴流形勢之分析78
6. 討論85
6.1. 大氣熱力特性的影響85
6.2. 低層噴流對激發及維持對流系統之影響86
7. 結論92
參考文獻98
自 傳…..………………………………………………………101

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