A Preliminarily Statistic and Synoptic Study about the Basic Currents over Southeastern Asia and the Initiation of Typhoons ^{* # &}

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 equatorial convergence zone between the equatorial westerlies and trade wind of West Pacific Ocean. The equatorial westerly is a large scale and quasi-steady phenomenon; 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.