THE STRUCTURE ANALYSIS OF A TYPICAL MEIYU FRONT

There existed a typical Meiyu front along the mid-lower Yangtze Basins during Meiyu period in 1999. The Meiyu front and rain belt extended eastward from Sichuan Province to Japan. Along the Meiyu front, there was a sharp contrast of temperature and hum idity. What's more, a few mesoscele vortexes moveed to the east along the Meiyu front, which produced severe rainstorms and floods in mid-lower Yangtze Basins. The results reveal that there is almost not emperature contrast in the lower level of Meiyu front because of the highly development of convection and rain. But it owns the typical Meiyu front structure at the upper level. In the lower level, the structure of meridional temperature likes "sandwich", for the relative low temperature in the Meiyu rain realm, and the relative high temperature along the other two sides. Under this condition, there forms a sharp temperature contrast belt between the cold air mass of Meiyu region and the relative warm air mass of the north land. Following the definition of Equatorial Front defined by Xie Yibing, we define this belt as Meiyu Equatorial Front. So the East-Asia Meiyu front system includes Meiyu Equatorial Front and Meiyu front under 600 hPa, but there is only Meiyu front above 600 hPa. To illustrate this structure more clearly, we provide an East-Asia front structure model.