乌鲁木齐风廓线雷达资料在暴雨天气分析中的应用

The Application of Wind Profiler Radar Products in A Heavy Rainfall Episode in Urumqi

利用乌鲁木齐风廓线雷达提供的风场资料、自动站逐时降水量和NCEP/NCAR每6 h再分析资料(1°×1°),详细分析了2012年5月19日15:00—20日04:00间乌鲁木齐暴雨天气过程。结果表明:高空急流与低空辐合区相配合产生的强垂直上升运动触发了此次暴雨天气;强降雨发生2 h前西北急流迅速下传,引发低层西北急流的加强,低层急流的加强与强降水有较好的对应关系,特别是1 500 m以下的西北急流;低层上升速度2 m/s可作为降水临界值,低层上升速度越大降水越强;强降水阶段整层大气折射率结构常数探测值在-128^-120 dB之内,表明整层大气水汽充沛;风廓线雷达产品(垂直速度、折射率结构常数)清楚地反映降水的开始、结束以及降水的强度,可为精细化预报提供参考。

Using the wind data from wind profiler radar in Urumqi, hourly rainfall data and NECP/NCARreanalysis data, the heavy rainfall episode in Urumqi from 1500 on 19th to 4：00 on 20th, May areanalyzed. The results indicate that the strong vertical ascending motion was produced by thecombination of the upper-level jet stream and the low-level convergence,which triggered this heavyrainfall. The northwest jet stream quickly passed clown 2 hours before the heavy rainfall, causing theenhancement of the low-level northwest jet stream, which is corresponding to the heavy rainfall,especially below 1 500 m. Low-level vertical ascending speed 2 m/s can be used as rainfallthreshold. The rain would be heavier as the low-level vertical velocity became larger. During heavyrainfall period the value of whole layer of atmospheric refractive index structure constant （RISC）ranges between -128--120 dB, which shows that water vapor is abundant. The wind profiler radarproducts （vertical velocity, refractive index structure constant） reflect the start and end, and theintensity of precipitation clearly, providing reference for the refine forecast.