Abstract:

Based on conventional observation data, NCEP/NCAR reanalysis data, radar data and cloud images of FY-2 satellites, two severe convection processes occurring on 20 March 2013 and 29 April 2013 in Guangxi were comparatively analyzed. The results show that  the main affecting systems of “0320” process were upper cold trough, low level shear and surface front, while for “0429” process, they were upper trough and southwest low level jet. Compared with “0429” process, there were negative temperature change in 24 hours on 500 hPa, bigger temperature difference between 850 hPa and 500 hPa, bigger CAPE, stronger vertical wind shear, appropriate height of 0 ℃ and -20 ℃ levels and dry in the upper level and wet in the lower level for “0320” process, which were conducive to occurrence of hail and gale weather. For “0429” process, there were deep wet layer, weak vertical wind shear and thick warm cloud layer, which were conducive to the heavy rainfall. Convection of “0320” process was triggered by front, surface convergence line and dew point front together, while for “0429” process, it was triggered by surface convergence line. Large hail process on 20 March 2013 was caused by many isolative severe convective storms with long cirrus plume. The structure of super-cell storm was obvious, and there were fast moving speed, stronger echo and higher stretching height of echo. However, the heavy rainfall process on 29 April 2013 belonged to mixed cloud precipitation with the cumuliform cloud and stratiform cloud. The convective cloud clusters were nearly round or oval, and they moved slowly, merged and strengthened. Compared with “0320” process, the echo of “0429” process was weak, the stretching height of the strong echo was low.

Key words: severe convection, convection parameter, radar echo, satellite cloud image, comparison

摘要：

利用常规探测资料、NCEP/NCAR再分析资料、雷达、FY-2系列卫星等资料，对2013年3月20日大风冰雹过程（简称“0320”过程）和2013年4月29日强降水过程（简称“0429”过程）进行对比分析。结果表明：高空冷槽、低层切变、地面锋面是“0320”过程的主要影响系统，而“0429”过程的影响系统主要为高空槽、西南低空急流。“0320”过程500 hPa上有明显的24 h负变温，850 hPa与500 hPa的温差较大，CAPE较大，垂直风切变较强，0 ℃、-20 ℃层高度明显偏高，上干冷、下暖湿有利于冰雹大风的发生；“0429”过程湿层深厚，垂直风切变较弱，暖云层较厚，有利于强降水的产生。“0320”过程由锋面、辐合线和露点锋共同触发，而“0429”过程由地面辐合线触发。“0320”过程由多个孤立且带有长云砧的强对流风暴造成，超级单体风暴结构明显，移速快，回波强度强，强回波伸展高度高；“0429”过程是积状云为主的层、积状云混合降水，对流云团近乎圆形或椭圆形，移动缓慢，合并加强，回波强度相对偏弱，强回波伸展高度偏低。

关键词: 强对流, 对流参数, 雷达回波, 卫星云图, 对比