Using the regular aerological data in the summers of 1981 and 1982

the relationship between the activities of the South China Sea typhoons and the circulation systems of the East Asia Monsoon is discussed. The results show: 1

The cross-equatorial air currents at about 105°E strengthened

and ITCZ developed when the cold high Over Australia intensified. The South China Sea typhoons occurred during the dates of descening of the cold high over Australia. 2

The South-west current is an important belt of energy transport for the generation of the typhoons. 3

The development of the Southern branch of the easterly jet and the downward transport of the momentum of the nothern branch of the easterly jet favour the development of the typhoons. 4. The cyclonic waves coming from the Western Pacific promote the generation of the lows over the South China Sea.