组网雷达在暴雨过程低层水平风场反演试验初步研究

Preliminary Study on Retrieval Experiments of Low-level Horizontal Wind Field for Two Heavy Rainfall Cases Based on Two Radar Networks

从实际应用考虑,略去基于组网雷达的两步变分法目标函数中与反射率因子有关的约束项。为验证简化后的两步变分法的风场反演能力及稳定性,设计了水平分辨率、垂直层数、垂直分辨率、反演区域以及反演中心等约束条件对水平风场反演结果影响的敏感性试验。通过对重庆地区的2次暴雨过程在3 km高度上的水平风场反演试验分析,发现简化后的两步变分法对暴雨过程低层水平风场的反演具有较高的可靠性,且各设计试验条件下的反演结果较稳定。具体表现为反演的水平风场能够反映出暴雨过程的中-β尺度流场结构特征,且2次过程在低层存在的中-β尺度强回波区与反演风场辐合区配置较好。

Considering the operational applications,the constraint term associated with reflectivity factor in objective function of the two-step variational method based on two radar networks was omitted. For the sake of verifying the capacity and stability of the simplified two-step variational method to retrieve the wind field,the sensibility experiments by changing constraint conditions such as horizontal resolution,vertical layers,vertical resolution,retrieval area and retrieval center were designed,and which were applied to the retrieval of horizontal wind field on 3 km height for two heavy rainfall processes occurring from 18 to 19 June 2010 and 3 to 5 July 2010 in Chongqing. The results show that the simplified two-step variational method to retrieve the low-level horizontal wind field under different constraint conditions during two rainstorm processes was more reliable and stable. The retrieved horizontal wind field could reveal the characteristics of flow field structure for the meso-β scale system during the heavy rainfall processes,and the configurations of the strong echo zone with the meso-β scale in low level and the convergence zone of retrieved wind field were better.