非常规探测资料在江西一次暖区暴雨过程分析中的应用

Applications of Unconventional Observation Data on the Analysis of Warm Area Rainstorm Happened in Jiangxi

综合运用风廓线雷达等多种非常规探测资料,对江西省2013年6月29日暖区大暴雨进行分析,并对比6月28日锋面暴雨,归纳总结短时大暴雨发生的一些前兆信号及可用指标。结果表明:1)风廓线雷达能直观反映暴雨区附近中小尺度扰动、近地面弱冷空气入侵、急流脉动发展等特征,1.5—4 km高度层出现16 m/s以上急流对暖区暴雨发生有利,对强降水的发生有1—3 h提前指示作用。2)0.5—1.5 km高度层正的风垂直切变带对应降水发生发展,正速度带中大于4 m/s风速切变对应下游降水加强。3)PWV值在强降水发生前常出现持续上升或波浪上升。PWV值达到65 mm且维持较长时间,同时配合动力触发条件,有利于强降水的发生;PWV值低于60 mm并持续性下降,对应降水趋于减弱停止;强降水落区出现在湿舌前端的PWV等值线密集区内。4)此次强降水主要发生在TBB小于-40℃区域前端的等值线密集区和地面辐合线附近,且地面辐合线的强度、移向与新生单体的发展密切相关;强回波不断在地面辐合线附近合并加强形成"列车效应",雷达回波上逆风区、急流核、速度对等特征的出现有利于强降水的维持。

The unconventional observation data, such as wind profile radar data, are used to comparatively analyze the different rainstorms occurred on June 28th and 29th 2013, and some of the precursor signals and available index for short time rainstorms are summarized. The results show that： 1 ） The wind profiler radar can directly reflect the features of small and meso-scale disturbance near the rainstorm area, the weak cold air intrusion near surface, the development of jet flow fluctuation, and so on. And southwest jet,＇ with the wind speed more than 16 m/s at 1.5-4.0 km altitude, is favorable for rainstorm maintaining in the warm zone, which is useful for forecasting rainstorm 1-3 hours in advance. 2） Positive wind vertical shear belt locating at 0.5-1.5 km altitude is corresponding to the occurrence and development of precipitation, and wind speed shear more than 4 m/s in positive velocity belt can increase the downstream precipitation. 3 ） Before the occurrence of heavy rain, the PWV value always presents persistent rise or wavy rise. If the PWV value keeps more than 65 mm for a long time, the heavy rain will occur with the favorable dynamic trigger. While if the PWV value keeps less than 60 mm and decrease continuously, the heavy rain will weaken down or finish. Strong precipitation zone appears in the dense area of PWV isoline in the fore-end of wet tongue. 4） This rainstorm mostly happened in dense TBB isoline part of front area with TBB 〈-40 ~C and near surface convergence line. The intensity and moving direction of surface convergence line are closely related to development of new cells. The merging and development of strong echo near surface convergence line are favorable for ＂train effect＂. Contrary wind, jet stream core and velocity pairs in the radar echo are helpful for rainstorm maintaining.