关键词: 飑线, 强度, 垂直风切变, 冷池, 移动

Abstract: Based on the conventional observation data, regional automatic station data, composite reflectivity factor of Doppler radar and NCEP GFS analysis field with 0.25°×0.25° spatial resolution, the intensity and motion characteristics of a strong squall line process affecting Fujian Province on 26 April 2016 were analyzed. The results show that the differences of intensity, structure, motion and induced weather were significant during the early stage and the late stage of the squall line process. During the early stage, the intensity of the squall line was strengthened by strong vertical wind shear in low level of troposphere and dry and cold air involvement in middle level. Furthermore, the triggering of ground convergence line, the dynamic lifting of low-level shear line and the vapour transportation of low-level jet were more favorable to development of the squall line. During the late stage, the intensity of the squall line weakened, and it merged and restructured as a back-building squall line with new convective cells in Longyan of Fujian Province and northern Guangdong Province, but the new system was quasi-stationary and caused a wide range heavy rainfall in the middle of Fujian Province. The improved vector technique of convective system motion can estimate the motion of forward-propagating and back-building squall line, and the results were basically matched with the observation, which can be a valuable reference in short-term forecasting and nowcasting of severe convective weather.

Key words: squall line, intensity, vertical wind shear, cold pool, motion