雙颱風一芙安與艾倫一之研究及其合併後對台灣之影響

A Case Study of Typhoon Pair (Ellen and Fran) and Their Effects to Taiwan

林財旺

T. W. Lin

　　Typhoon Ellen and Fran almost formed at the same time over the Pacific Ocean to the east and southeast of Taiwan respectively. The distance between the centers of these two storms was about 500NM when they just formed, and the location of Ellen was to the north of Fran about 3 degrees of latitude.
　　These two storms rotated after their formation. Fran moved to the north, Ellen moved to the south and her circulation was finally destroyed and mingled with the circulation of Ellen. Since the maximum sustained winds of these two storms were all less than 50 KTS, they had easily mingled into one, and the variation of their trajectories were all less than 270 degrees before the mingling had completed. For the strong typhoons the variation of the trajectories of the pair might be more than 360 degrees before the mingling had completed.
　　Typhoon Fran formed at 20.6°N 127.3°E. At first it moved to the northeast, then turned to the north, then to the northwest. If there were no Fujihwara effect, It would move to the open sea north to Taiwan and spare this island. As it was under the influence of Ellen, Fran finally turned to southwest and entered Taiwan Strait. The details will be discussed in the text.