Cause Analysis of Rainy Fog and Radiation Fog in Chongqing

Abstract

With the NCEP reanalysis data and L-band radar data to analyze the circulation situation and the vertical structure of temperature, humidity and wind speed of radiation fog and rainy fog in Chongqing by compositely analysis method. The result shows that: When radiation fog takes place, the 500hPa areas of Central Asia and Qinghai-Tibet plateau become high pressure ridge, and the cold front have reached the South China. When rainy fog takes place, the 500hPa area of Qinghai-Tibet plateau is controlled by the low pressure trough and the center of ground cold anticyclone will be in the northern area of China. Temperature inversion in the surface layer is obviously stronger when it’s radiation fog than rainy fog; And the moisture vertical structure are reflected as being dry in the upper layer, being moist in the lower layer when radiation fog occurs, and the moisture layer being deep and thick when rainy fog takes place. However in regard to wind speed, it’s slow in the surface layer during the formation of each fog.