雲簇系統如何發展成熱帶低壓的過程是科學家所重視的研究題目之一，因為熱帶低壓往往會形成颱風，本研究的目的即在分析南海地區的雲簇系統發展成熱帶低壓過程中，雲簇系統的生成與環境場變化。首先利用SSM/I及QuikSCAT衛星資料反演出總合成熱能與近海面渦度場，分別建立客觀熱力與客觀動力指數，再分析熱帶低壓環境場的熱力與動力條件，嘗試歸納出預測熱帶低壓生成與否之機制。 結果顯示:南海區域從雲簇系統發展成熱帶低壓之客觀動力指數與客觀熱力指數的時序變化中，熱帶低壓是否形成的關鍵因素是要同時達到兩指數的門檻值，在JTWC發佈為熱帶低壓前一至兩天，就可判斷此雲簇系統繼續發展成熱帶低壓的可能性。換言之，此方法有助於以客觀角度提前篩選出較易形成熱帶低壓的雲簇系統，以利颱風的防災減災。 The process of cloud clusters developing into tropical depressions is an important subject which scientists are interested. In this study, we analyzed the environmental field variations related to the cloud clusters which were developing into tropical depressions over the South China Sea. We employed SSM/I and QuikSCAT satellite data to estimate the total heat energy and sea surface vorticity ,and then establish the objective heat index and the objective dynamic index, respectively. We analyzed the variations of the objective heat index and the objective dynamic index of those tropical depressions, and tried to find the main mechanism as whether the tropical depressions will occur or not. The result shows that the process of cloud clusters developing into tropical depressions over the South China Sea. The key factor of whether a tropical depression will occur or not is that its objective heat index and the objective dynamic index both are higher than the thresholds. This result can allows the warning time is shifted to be one to two days earlier before the official JTWC warning is announced. In other words, this research provide an objective method for earlier predicting whether a tropical depression will occur or not .
