两次飑线过程中短时强降水和冰雹强度差异及成因分析

利用常规观测资料、雷达反射率资料和NCEP/NCAR提供的FNL再分析资料,结合中尺度非静力模式(WRF)的模拟结果,分析了2009年6月3—6日两次飑线过程的环境背景、移动路径以及短时强降水和冰雹强度的差异及其产生的原因。结果表明:移动路径的差异主要由500 hPa以下引导气流不同造成。数值模拟和水汽试验得出,两次过程在垂直方向的水汽条件存在明显差异可能是短时强降水及冰雹强度不同的主要原因。700~850 hPa水汽的多少对霰(雹)比含水量的大小非常敏感,这一区域的水汽增多,则霰(雹)比含水量明显增加,反之,有明显减少。

Analysis on intensity difference and its causes of short-term heavy rainfall and hail in two squall line processes

Based on the conventional observation data,radar reflectivity data and FNL reanalysis data from NCEP/NCAR, and combined with the simulation results by non-hydrostatic mesoscale model, the environment background, moving path, intensity difference and its causes of the short-term strong rainfall and hail in two squall line processes during June 3 to 6,2009 were analyzed. Results indicate that the different steering flows below 500 hPa lead to the different moving paths. Numerical simulation and water vapor test show that the main reason why the intensity difference of short-term precipitation and hailstone occurred on June 3 and June 5 is the differences of water vapor in vertical structure. The water vapor content at 700-850 hPa is very sensitive to graupel(hail). When the water vapor in this area increases, the water proportation in graupel(hail) increases significantly, otherwise, it significantly reduces.