绥中一次暴雪伴雷电天气过程的成因分析

为了探讨绥中一次暴雪伴雷电天气过程的成因,利用常规观测资料、NCEP每6h间隔的1°×1°的再分析资料和营口多普勒雷达的资料,分析此过程的天气形势特点、高低空急流的作用、雷达回波的特征及反映动力、热力和水汽条件的相关物理量场的特征。结果发现:雷电发生在对流层中层的西南风急流和底层偏东风均处在最强的时刻,当对流云团发展到-20℃温度层时,温差起电产生雷电;雷电发生在低层850hPa附近存在的逆温层消失之后,同时配合低层水汽的辐合,产生了暴雪天气;雷电和强降雪发生在大气底层南风和北风转换的过程中,强降雪的时间与冷空气扩散加强的时间比较一致,当冷空气扩散到整个大气底层时强降雪结束;引起雷电和强降雪的对流不稳定层结主要处在对流层中层,并为上升运动的发生提供了动力和热力条件,促使雷电发生和强降雪的维持。

Cause Analysis on a Weather Process of Blizzard With Thunder In Suizhong

In order to investigate the causes of blizzard with thunder in Suizhong, based on conventional observa- tions, NCEP/NCAR reanalysis data and Yingkou Doppler radar data, the article analyzed the weather situation, the upper and lower level jets, and the radar echo and related physical quantities which reflected dynamic, ther- mal and water vapor conditions. The results showed that： thunder caused by temperature difference, occurred in the moment when middle-level southwest wind and low-level east wind were the strongest and convective cloud developed to -20~C temperature layer. Thunder occurred after the inversion layer on 850hPa disappeared, and snowstorm occurred in conjunction with the low-level moisture convergence. Thunder and heavy snowfall oc- crated in the process of conversion of the low-level south wind and north wind, and heavy snowfall was consis- tent with the cold air diffusion until it spread to the whole low-layer. Convective instability stratification caused thunder and heavy snowfall mainly in the middle of troposphere, and provided dynamic and thermal conditions for the upward motion, prompting occurrence of thunder and maintenance of heavy snowfall.