Study On Tropical Cyclone And Precipitation In South China Under The Warming Environment

Based on the daily precipitation data at 740 stations in Chinese mainland from1957 to 2004, this paper uses the tropical cyclone precipitation separationmethod-OSAT to separate the Tropical Cyclone Precipitation (TCP) from theprecipitation data in South China. It also analyses the interrelated Tropical Cyclone(TC) there. The results show that:(1) There is a decreasing trend of the frequency of both TC and landfalling typhoons in South China. Under the warming environment, the downtrend of the frequency of TC is more obvious than before while that of landfalling typhoons is not so notable. Also, their cycles are larger and the probability of their extremums has reduced a little.(2)In warming environment, the average and intensities of TC in South China are decreasing more quickly, but the probability of its extremum is less than before. The decrease of the frequency of landfalling typhoons is mainly caused by the the decrease of the frequency of super typhoons. Under the warming environment, the frequency and proportion of super typhoons are reduced to a large extent but those of typhoons and severe typhoons have minor changes.(3) The annual TCP in South China accounts for 10-20% of the total precipitation, but its directional distribution is not even at all. It has a trend of sharp cutoff from coastal areas to inland areas in the direction of northwest, so are the contribution percentages of TC precipitation. The westmost areas effected by TC moved westward in the late 1990s.(4) Over the recent fifty years, the TCP in South China is has been falling and its downtrend is more obvious than that of the entire country. The extremum of TCP has a twelve-year oscillation period, which is 2-4 years shorter than that in North China. The extremum of TCP in South China and North China has a relation of antiphase. In warming environment, the landing area of TCP tends to be more centralized and the TCP period is 2-5 years longer than before; while the amount of TCP is reduced and this reduction appears more than ten years earlier compared with North China. The changes of TCP are closely related to those of TC frequency.