利用天气雷达平均散度产品分析短时强降水大气低层辐合特征

Analyzing the low level atmospheric convergence characteristics in the short-time heavy precipitation using average divergence products retrieved from weather radar

使用湖北新一代天气雷达平均散度反演产品,结合高空、地面和雷达观测资料,统计分析了短时强降水发生发展过程中大气低层辐合的演变特征,检验低层辐合的预警指示意义,并解释其天气意义。结果表明:低层辐合演变一般具有单波谷或双波谷特征,且中尺度特征明显。在强降水前期低层散度为辐合或由辐散转为辐合,强降水集中期低层辐合发展至最强,之后逐渐减弱,强降水后期低层转为辐散。低层辐合且明显增强可能具有预警指示意义。雷暴冷出流和低空急流加强对低层辐合有重要贡献。

Using the averaged divergence retrieval data based on Hubei new generation weather radar,combined with upper,surface and radar observation data,the evolution characteristics of the low level convergence in short-time heavy precipitation was analyzed.The warning significance was tested and the synoptic significance of low level convergence was explained.The results show that the evolution of low level convergence had the structural characteristics of single trough or double trough with the obvious mesoscale feature.In the early stage of heavy precipitation,the low level divergence is convergent or divergent to convergent.The low level convergence develops to the strongest stage in the concentration stage,then weakens gradually.At later stage,the low level convergence turns to divergence.The low level convergence and obvious enhancement may have the significance of early warning.Thunderstorm cold outflow and low-level jet reinforcement have important contributions to the low level convergence.