一次东北冷涡暴雪过程分析

利用NCEP再分析资料和实况资料,对2013年11月16—20日东北冷涡暴雪过程进行分析。结果表明,暴雪发生在对流层低层辐合线附近,对流层低层有暖脊、中层有冷槽。暴雪区水汽主要来源于东北地区东部海上,对流层低层水汽通量在2 g/(cm·hPa·s)以上。东北冷涡发展期,斜压性特征明显,有利于降雪增强;冷涡成熟期、减弱期,显示出正压的特征,降雪减弱。等θse线陡立密集区对流稳定度小,有利于特大暴雪发生。

Analysis on an Snowstorm Event Caused by Northeast Cold Vortex

The routine surface observational data and NCEP reanalysis data are used to analyze a persistant snowstorm process of a northeast cold vortex in the Northeast China during 16-19 November,2013.The results show snowstorm appears near convergence line of the low troposphere,and there is warm ridge in the low troposphere and cold trough in the middle troposphere.The source of water vapor is the seas off northeast China's eastern coastline,and water vapor flux at lower troposphere is above 2 g/(cm·hPa·s).At the initial stage,its baroclinic characteristic is obvious,which provides advantageous condition for the occurrence of snowstorm.At the stage of maturity and decay,snow tends to weaken.Snowstorm often occur in the stiff and dense zone of the θse contour line,where the convective stability is small.