强冰雹和短时强降水天气雷达特征及临近预警

Radar Features and Nowcasting of Severe Hail and Short-Time Heavy Rainfall

利用恩施多普勒雷达和常规分析资料,详细对比分析了2007—2008年发生在恩施山区强冰雹和短时强降水天气过程中的雷达产品特征。在此基础上,找出了适合恩施山区强冰雹和短时强降水天气的雷达临近预警指标:选取负温区回波厚度≥7km、CR强中心回波强度≥55dBz、强回波梯度≥15dBz·km^(-1)、45dBz强回波伸展高度≥7.5km、累积液态含水量(VIL)密度≥3.2g·m^(-3)和雷达风廓线1.8～6.1km风垂直切变均值≥2.3×10^(-3)s^(-1)作为强冰雹临近预警指标;当满足组合反射率(CR)强中心回波强度、VIL密度、40dBz强回波伸展高度和雷达风廓线(VWP)上1.8～6.1km风垂直切变值达43.0dBz,1.1g·m^(-3),7.0km和1.9×10^(-3)s^(-1),可以考虑该站点及附近地区进入短时强降水临近预警状态,并利用2009年发生的强冰雹和短时强降水天气过程检验了这些临近预警指标性能。

Using Enshi Doppler radar and MICAPS data,the radar product characteristics are conducted by the comparative analysis between severe hail and short-time heavy rainfall occurring in the Enshi mountain area during 2007 to 2008.On this basis,some radar nowcasting indicators of severe hail and short-time heavy rainfall are found and chosen which are suitable for the Enshi mountain area：the thickness of the negative temperature region echo≥7 km,CR strong central echo reflectivity≥55 dBz,strong echo gradient≥15 dBz·km^-1,45 dBz strong echo height≥7.5 km,VIL density≥3.2 g·m^-3,and VWP shear means≥2.3×10^-3 s^-1 are selected as nowcasting indicators of approaching severe hail;while the strong central echo reflectivity,VIL density,40 dBz strong echo height and wind profiler radar on the VWP shear means（1.8—6.1 km） are 43.7 dBz,1.1 g·m^-3,7.0 km and 1.9×10^-3 s^-1,the nowcasting status of short-time heavy rainfall to the site and the surrounding areas is very appropriate.Finally,the severe hail and short-time heavy rainfall events occurring in 2009 are adopted to test the performance of these nowcasting indicators.