雙熱帶氣旋的氣流場分析與路徑預報

Discussion on the Observed Movement of Binary Tropical Cyclones in the Indian Ocean

何台華(Tai-Hwa Hor) ； Gandikota V. Rao

《大氣科學》 18卷4期 (1990/12) Pp. 309-325

摘要

在印度季風開始之前或衰竭之際，印度洋上有時可見成對的熱帶氣旋出現，其中一個位於赤道北邊，另一個則在赤道南邊，這些氣旋對的移動並不完全受導引氣流的主宰，而是需要考慮它們彼此間流體動力的牽引作用。民國68年（西元1979年）5月6日至12日有一雙熱帶氣旋發生在印度洋，而且以赤道分隔。本文利用Lamb（1972）所描述的方法計算此氣旋對的藤原參數再加上駛流的考慮，最後預測它們未來的位置。結果顯示此對氣旋具有藤原效應式的移行，而且24小時的預測可信度高，與實際觀測位置相差150公里，但18小時以上的計算和當氣旋接近陸地時則不盡理想。

關鍵字

雙熱帶氣旋 ； 藤原效應 ； 駛流

並列摘要

In the pre-monsoon season two cyclonic vortices appear occasionally over the Indian Ocean, one south and a second to the north of the equator. The movement of these vortices is not guided by any well defined steering flow. Under such a circumstance the two vortices may interact hydrodynamically, influencing the path of each. This interaction was first studied by Fujiwhara in a laboratory. During 9-12 May 1979 binary tropical cyclones were noted over the Indian Ocean. The observed movement is explained and the interaction between these tropical cyclones and their environment is calculated by combining the Fujiwhara deflection and the steering flow. The result shows that within 24 hours the predicted location of the pair is reasonable and applicable.

並列關鍵字

binary tropical cyclone ； Fujiwhara effect ； steering flow