The Characteristic Analysis Of Diurnal Variations Of Precipitation Over Southern China Before Typhoon Landfall

This paper used JMA best trackdata,TRMM 3B42 hourly satellite precipitation dataset and JRA55 6-hourly reanalysis data from1998-2017.The diurnal variations of precipitation over Southern China before the arriving of typhoon rain belt were studied.Specifically,these typhoons were originated in the Northwest Pacific and its moving path located in the south of Taiwan Island and landed in Guangdong province.The following conclusions are drawn:(1)There are two types of impacts of typhoon to South China on the daily precipitation in South China.Under the influence of type I,the daily precipitation intensity in South China is significantly enhanced,especially in the afternoon,and the probability of peak precipitation in the afternoon is also significantly increased;under the influence of type II typhoon,the daily precipitation intensity in South China is obviously weakened,and the precipitation in the afternoon weakened and the early morning precipitation increased,The probability of daily precipitation peak decreases in the afternoon and increases in the morning.(2)In addition to the type I typhoon originated in October,the daily precipitation in the key area decreased significantly under the influence of two types of typhoons,especially the daily precipitation of type II typhoon;the peak value of daily precipitation in South China under the influence of type I typhoon also appeared in the morning and night,and the peak value of precipitation under the influence of type II typhoon occurred in September except in the afternoon,night to morning,but in August the peak value occurred in the night;typhoon intensity has little effect on daily precipitation,the typhoon intensity is mostly tropical storm or typhoon When the first rain band reached South China.(3)Under the influence of type I typhoon,the water vapor transported from the sea to the land is more,and the water vapor content in the lower land layer in South China is large,so the precipitation is more;under the influence of type II typhoon,the water vapor transported from the sea to land is less,and the water vapor content in the lower land layer of South China is small,then the precipitation is less.(4)The difference of precipitation peaks in South China is affected by the time when the unstable energy appears to be extreme.The extreme time of atmospheric instability under the action of type I typhoon occurs in the afternoon,and the precipitation is more likely to form the precipitation peak in the afternoon;type II typhoon occurs mostly from night to morning,and the peak value of precipitation is more inclined to night to morning.