基于CMA-BJ的北京地区雷达弱回波区径向风同化及其对暴雨预报的影响OA

In order to utilize radial velocity observations within the weak echo region and investigate the application of their assimilation on regional model forecasts,a cyclic assimilation and forecasting experiment based on the CMA-BJ 2.0 system was conducted for a heavy precipitation event in southwestern Beijing.The data analysis revealed that the radial velocity in the weak echo region is primarily distributed around the periphery of the convection,with substantial data available at both high and low atmospheric levels.The cyclic assimilation and forecasting experiment demonstrate that assimilating radar radial velocity observations in weak echo region,in addition to those from strong echo region assimilation,can gradually enhance the overall dynamics of the analyzed field.Furthermore,this approach improves the forecast accuracy of conventional elements in both the high and low atmospheric layers.This results in more reasonable adjustments to the dynamics,thermal,and water vapor fields of the model,effectively enhancing the prediction of 3 h and 6 h precipitation.The study highlights the significant role of radial velocity assimilation within the weak echo region in improving convective forecasting,providing valuable insights for operational applications.