A PRELIMINARILY STATISTIC AND SYNOPTIC STUDY ABOUT THE BASIC CURRENTS OVER SOUTHEASTERN ASIA AND THE INITIATION OF TYPHOONS
HSIEH YI-PING, CHEN SHOU-JUN, CHANG I-LIANG, HUANG YIN-LIANG (Peking University)
The relation between the basic currents of the low latitudes and the initiation of typhoons is investigated statistically and synoptically by means of recent aerological data. It is shown that about 80% of typhoons developed in the eastern part of the equatorical convergence zone between the equatorial westeries and trade wind of West Pacific Ocean. The equatorial westeries is a large scale and quasi-steady phenomeanon therefore it is probably reasonable to be called "basic current" and typhoons are considered as vortices of smaller scale. There is a quite definite relationship between the time, position, frequency of the initiation of typhoons and the position, strength of the basic currents in the low latitudes. There is a quasi-periodical variation of the strength and position of the basic currents with a period longer than one month. This fact may be helpful for the extended forecast the initiation and development of typhoons.