Statistical analysis of mesoscale convective system(MCS) in the context of the cold vortex

摘要

This study based on the definition of cold vortex and 60 cold vortex were identified from April to September in 2005-2011.The cold vortexformed mainly in Mongolia and the northeastern of China.Meanwhile,according to the MCS size,it was classified asmeso-αmesoscale convective system(MαCS) and meso-β mesoscale convective system (MβCS).Then according to the shape,MαCSwas classified as mesoscale convective complex (MCC) and persistent elongated convective system (PECS).Furthermore,MβCSwas classified as meso-β circular convectie system (MβCCS) and meso-β elongated convective system (MβECS).Using the FY-2C and FY-2E geostationary satellite infrared digital image data,the MCSs were identified at the context of the cold vortex,the spatial-temporal characteristics and relationship between cold vortex and MCS were also analysis.The resultsshow that:(1) 61 MCSs were identified in the 60 cold vortex process,MCS mainly initiated in the Northeastern and North China,MCC and PECS generated more decentralized; MβCC mainly concentrated in Northeastern and North China,MβECS mainly concentrated in Northeastern China (fig.1).(2) Most of MCSs initiated in June,the number is 16.MCSs initiated less in September (fig.2).Most of MCSs generated in the afternoon and evening.At that moment,the convection was prosperous andconducive to the generation of MCS.MCSs matured at night and dissipated in the early morning (fig.3).(3) Most of MCSs moved from the west to the eastat the context of the cold vortex,it's consistent with the moving weather system of mid-latitude westerly in China.But because of the cold vortex and others weather system,there were different moving path (fig.4).(4) Most of MCSsmainly generated in the stage of cold vortex development.(5) MCS mainly initiated in the south of cold vortex,and few in other parts (fig.5).(6) MβCSs from the initiation to mature stage were faster than MαCSs,and the durationwere shorter than MαCSs (fig.6).