关键词: 暴雪, 多普勒雷达, 回波, PPI基本反射率, 径向速度, 定性定量分析

Abstract: Based on the circulation patterns at the upper air and surface, numerical weather prediction forecasting products from the ECMWF model, Doppler radar products from C-band such as reflectivity factor, radial velocity and VWP products in Datong, the heavy snow process on November 9-10, 2009 was analyzed. The results indicate that the surface return current and jets in upper and lower levels are the main reasons causing the heavy snow. The echoes characteristics of a heavy snow and a continuous rainfall are similar. The convergence and divergence can be estimated using a direction of the zero line, the areas of the positive and negative velocity and radial velocity value. They can also be calculated using the curving extent of zero velocity line and the included angle between zero velocity point in the stationary range and radar center line. The results calculated using the two methods are in good consistency. Both could be used to judge convergence and divergence quickly at work. Doppler radar wind profile data per 30 minutes could be obtained by rehandling primeval data, and it can display clearly the vertical structure of wind field of the heavy snow and its changes and it can reflect intuitively the wind field features.

Key words: Heavy snow, Doppler radar, Echo, PPI reflectivity, Radial velocity, Qualitative and quantitative analysis