2018年1月江苏3次致灾暴雪成因对比分析

Comparative analysis on causes of three disastrous snowstorms in Jiangsu in January 2018

应用常规天气图资料、FY-2E云顶亮温(TBB)资料、多普勒雷达观测资料和NCEP/NCAR 1°×1°再分析资料,对江苏2018年1月3—4日(简称“01·04”过程)、1月24—25日(简称“01·25”过程)和1月27—28日(简称“01·27”过程)3次暴雪过程进行了对比分析。结果表明:1)3次暴雪过程都是在500 hPa高空槽、中低层切变线、700 hPa西南急流和地面冷空气的共同影响下产生的;暴雪过程中水汽主要来源于中层,降雪期间逆温层结始终存在。2)不同之处是,“01·04”过程中层暖湿气流先形成,水汽条件更好,而后弱冷空气自低层楔入,促使暖湿气流抬升,上升运动发展更为旺盛;“01·25”过程和“01·27”过程低层先形成冷垫,而后中层暖湿气流增强沿冷垫爬升,冷垫更冷,“01·25”过程逆温更强。3)暴雪过程中TBB稳定低值期基本可以反映强降雪时段;“01·04”过程中有弱对流发展,造成降雪强度大。

By using conventional meteorological data,FY-2E black-body temperature(TBB)data,Doppler radar observations,and NCEP/NCAR 1°×1°reanalysis data,three snowstorm processes in Jiangsu Province from 3 to 4(“01·04”process),from 24 to 25(“01·25”process),and from 27 to 28(“01·27”process)January 2018 are comparatively analyzed.The results are listed as follows.1)The three snowstorms are all caused by the joint influence of upper-level trough at 500 hPa,shear line at middle and lower level,southwest jet stream at 700 hPa,and surface cold air.During the snowstorms,water vapor mainly comes from the middle level and inversion stratification persists.2)There are differences between the three snowstorms.In the“01·04”process,the warm and wet air flow in the upper level is formed in advance with better water vapor condition,and then the weak cold air wedges in from the lower level,which prompts the warm and wet air to rise,so the upward movement is stronger.In the“01·25”process and“01·27”process,the cold air cushion is formed first at the lower level,and then the warm and wet air in the middle level is intensified and climbs along the cold air cushion,which is much colder.In the“01·25”process,the temperature inversions is stronger.3)The stable low value period of TBB during rainstorms can basically reflect the heavy snowfall period.Weak convection develops in the“01·04”process,which causes intensified snowfall.