中文摘要：

基于集合和奇异值分解的三维变分同化方法（SVD-En3DVar）对2009年6月14日江苏地区的一次飑线过程进行多普勒雷达资料同化预报数值试验,以检验该方法在这类尺度较小的强对流天气过程中的同化应用效果。同时,还讨论了SVD-En3DVar的分块局地化方案中水平半径对此次飑线过程同化效果的敏感性,并应用WRF 3DVar进行了平行对比试验。数值试验结果表明,应用SVD-En3DVar方法同化多普勒雷达资料后能够有效调整风场、比湿和位温等状态变量,同化预报结果对分块局地化方案中水平半径参数较为敏感,水平分块半径为50 km时对组合反射率的预报效果最好。SVD-En3DVar和WRF 3DVar两种同化方法同化雷达资料后都能够提高雷达组合回波的预报水平,但SVD-En3DVar方法的效果明显优于WRF 3DVar同化系统,对回波带位置及其向东南方向发展趋势的预报和观测回波较为一致。

英文摘要：

The effectiveness of using a three-dimensional assimilation method based on the forecast-ensemble and singular value decomposition（SVD-En3DVar） to assimilate real Doppler radar observations is investigated by applying the technique to a squall line case occurred on June 14,2009 over Jiangsu Province of China.The assimilation and forecast experiments are conducted with the Weather Research and Forecasting（WRF） model.The impact of the localization parameters in SVD-En3DVar on assimilation skill is also examined and the identical assimilation experiments are performed with WRF 3DVar as a comparison.The experimental results show that the SVD-En3DVar method has the ability to assimilate Doppler radar data effectively.The SVD-En3 DVar method is slightly sensitive to horizontal localization parameter for the convective-scale weather system.In this squall line case,the horizontal localization radius of about 50 km can achieve the best prediction of composition reflectivity;The radar data assimilation both using the SVD-En3DVar and WRF 3DVar all improves the prediction of reflectivity,and the SVD-En3DVar method outperforms WRF 3DVar.Compared with observed reflectivity,the predicted reflectivity with using SVD-En3DVar can capture the structure and evolution of the squall line well.