The Diurnal Variation Of Heavy Rain In South China And The Gravity Waves In Heavy Rain

The main objective of this study is to investigate the diurnal rainfall variation in south china by analyzing the TRMM (Tropical Rainfall Measuring Mission)satellite observation 3b42RT and eight land stations' precipitation and surface pressure in Jun 2006.Results show that most land and offshore areas exhibit more rainfall in 12-24LST ,while over most coastal areas rainfall peaks during 00-12LST. Precipitation peaks in 11-17LST over land of South China ,and reach its peak at 08LST with a secondary 14LST maximum over coastal areas of South China. Phase of the diurnal cycle reveals differences in these two areas. The dominant diurnal cycle feature of the heavy rain process from 8th June to 9th June in the year of 2006 in South China is a rainfall maximum in 17LST 8th June and 11LST 9th June over land, while over coast areas the dominant maximum occurs in the 02LST-08LST hours of 9th June. The diagnosis analysis based on the Fourier transform using both of surface presses and TRMM rainfall rate data come to the conclusions that distinct twelve hours period gravity waves occurred in the precipitation process and the precipitation have a diurnal cycle. Both the gravity waves and the precipitation spread out from coastal land to the ocean, indicating that the Gravity wares may have important impacts to the Diurnal variation precipitation.