一次冰雹天气过程的云系发展演变及云物理特征研究

利用中尺度数值模式WRF(Weather Research and Forecasting)的数值模拟,结合NECP/FNL再分析资料、地面、探空、多普勒雷达基数据和卫星产品等观测资料,综合分析了2014年3月30日发生在贵州省西南部的一次冰雹天气过程。研究了有利于冰雹发生的环流特征和环境条件,分析了冰雹云系的发展演变特征、云微物理结构特征,初步分析了冰雹形成的云物理机制。结果表明:此次冰雹天气是典型的低压辐合线型降雹类型,地面降雹位置位于700 hPa切变线和近地面辐合线附近及南侧;发生此次冰雹过程的对流云系经历了对流云系的初生阶段、合并加强阶段、成熟降雹阶段和东移阶段。贵州地区上空对流云系的微物理结构具有混合相云特征,高层为冰晶、雪,中层为云水、霰,低层为雨水、冰雹。霰和云水是形成雨水和冰雹的主要来源,霰撞冻过冷云水和霰的自动转化是冰雹形成的主要微物理机制。

Study on the Evolution of Hailstorm and Its Cloud Physical Characteristics

In this study, a hailstorm that occurred in southwest of Guizhou Province on 30 March 2014 is simulated using the mesoscale model WRF (Weather Research and Forecasting). Combined with NCEP/FNL reanalysis data, ground, sounding, Doppler radar data, satellite products and other observation data, this hailstorm process is comprehensively analyzed. In addition, the characteristics of the hailstorm and its environmental conditions, the evolution characteristics of the hailstorm and the characteristics of the cloud microphysical structure, the cloud physical mechanism of the hailstorm are analyzed. The results show that this hailstorm was a typical low pressure convergence line hailstorm, and the hail position on surface was at (or southern to) shear line at 700 hPa, closing to the ground convergence line. The convective cloud of this process underwent the initial stage, the consolidation stage, the mature hail stage and the eastward shift stage. Thus, the microphysical structure of convective cloud over Guizhou Province has the characteristics of mixed phase cloud with ice crystal and snow in upper layer, cloudwater and graupel in mid layer, and rainwater and hail in lower layer. The most important sources for the rainwater and hail are the graupel and cloudwater. During the process of hail formation, the accretion between graupel and supercooled cloudwater, and the automatic conversion of graupel are the main microphysical mechanism.