Analysis of squall lines occurrign in cold vortexes over Northeast China
Squall lines which occurred in cold vortexes over Northeast China were analyzed by using data observed at the Harbin weather station and other data sets. The results show that ① The squall lines mostly occurred when the cold vortexes developed strongly and were over the front regions,which had thermodynamically unstable structure. ② There are basically three necessary conditions for the occurrence of squall lines,i.e. unstable thermodynamically structure,convergence of water vapor in the low levels and strong convection.③ A mesoscale weather system occurred near surface. ④ The synoptic scale kinetic energy was transferred to the mesoscale system when the squall lines enhanced.