风廓线雷达在“7.19”大暴雨过程中差异特征分析

Difference Characteristics of Wind Profiler Radar in “7.19” Heavy Rainstorm

利用京津冀地区三部风廓线雷达资料,结合常规气象观测资料、加密自动站资料、NCEP再分析资料及雷达探测资料,针对2016年7月19~20日发生在京津冀地区的一次大暴雨局地特大暴雨过程进行分析。结果表明:此次降水过程分为两个阶段,第一阶段呈现短时雨强大且强度变化显著的对流性降水特点,第二阶段降水相对平缓,雨强显著减小;天气系统配置结构满足华北地区出现大暴雨的典型背景条件;强降水第一阶段发生前3,h出现双层低空急流,而强降水第二阶段低空急流的出现仅提前1~2,h,且并无双层低空急流现象。

Using three wind profilers in Haidian,Handan and Baodi as well as the conventional observation,automaticweather stations,NCEP/NCAR1,°×1,°reanalysis data,a heavy rainfall event in Beijing-Tianjin-Hebei region during19～20July2016was investigated.The results showed that there were two stages during the torrential rain.The first stagepresents convective precipitation with short-time and high rainfall intensity.The second stage presents smooth stratiformprecipitation.The synoptic scale circulation situations on19～20July were typical circulation pattern of North China heavyrain.The divergence in high-level and the deep convergence system in low-vortex and surface cyclone caused the continuanceof strong vertical upward motion.The southwesterly and southeasterly low-level jet supplies sufficient moisture conditionfor the occurrence of torrential rain.The wind profile radar showed that about3hours before the first stage of heavyprecipitation,there appeared doubled low-level jets while the low-level jet was about1～2hours before the second stage ofheavy precipitation without doubled low-level jets.