一次局地短时大暴雨中-γ尺度分析  

Analysis on a Meso-γ Scale of Local Short-Time Heavy Rainstorm

作　　者：王丽荣[1] 刘黎平[2] 王立荣[1] 郭卫红[1] 杨荣珍[1] 

机构地区：[1]河北省石家庄市气象局,河北石家庄050081 [2]中国气象科学研究院,北京100081

出　　处：《高原气象》2011年第1期217-225,共9页Plateau Meteorology

基　　金：国家自然科学基金项目(40975013);中国气象局预报员专项(CMATG2010Y02);公益性行业(气象)科研专项(GYHY200706004)共同资助

摘　　要：利用多普勒天气雷达和地面降水资料,应用四维变分风场反演方法,对2008年8月14日发生在石家庄城区西北部的局地短时大暴雨进行了深入分析,结果表明:(1)短时暴雨发生时,一般会出现反射率因子超过60 dBz的回波,而且径向速度图上会产生明显的辐合区。(2)依据回波顶高和垂直累积液态含水量产品能够提前18 min预报短时暴雨的发生。(3)四维变分风场反演产品能够清晰地展现短时暴雨发生前后低层的风场结构:首先在3 km以下有气旋性涡旋生成,再由涡旋前部的西南气流激发产生强对流回波,之后涡旋移动;但强回波附近始终存在风向的辐合,致使回波稳定维持,造成当地短时强暴雨。风场反演揭示的中-γ涡旋和风场辐合等小尺度系统,对短时强降水的落区及生消预报有较大的作用,跟踪风场的发展演变可以进一步认清局地短时暴雨发生的机理。A local short-time heavy rainstorm,which takes place in the north-west of Shijiazhuang on 14 August 2008,is analyzed by means of Doppler radar,ground automatic station data and 4DVAR wind retrieval method.The obtained conclusions are as follows：（1） In general,the radar reflectivity exceed 60 dBz and convergence zone exist in radial velocity PPI when short-time heavy rainstorm occur.（2） It is possible that the short-time heavy rainstorm is forecasted more than 18 min in advance based on the radar products such as ET and VIL.（3） 4DVAR method can clearly reveal the low-level wind field structure of rainstorm： A cyclonic vortex is first generated in the region of heavy rain,and then the southwest airflow in front of the vortex arouses severe convection echo which maintain stability because of the convergence always existing,and lead the local heavy rainstorm.Whereby,the meso-γ scale or small scale systems can be revealed by 4DVAR wind field retrieval,which can play an important role in forecasting the drop zone of heavy rainstorm,tracking the generation and evolution of meso-γ scale vortex,and understanding the mechanism of the local short-time rainstorm clearly.

关 键 词：局地大暴雨 雷达产品 四维变分风场反演 

分 类 号：P426.62[天文地球—大气科学及气象学]