关键词: 强对流, 对流参数, 雷达回波, 卫星云图, 对比

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