2022年初冬伊犁河谷一次极端暴雪过程诊断分析

Diagnostic Analysis of an Extreme Blizzard Process Over Yili River Valley in the Early Winter of 2022

利用常规探空和地面观测、NCEP/NCAR 1°×1°再分析等资料,采用天气学诊断方法对2022年11月22—24日伊犁河谷极端暴雪过程进行分析,结果表明:(1)此次过程为强锋区降雪,锋区内不断有短波东移,是暴雪发生的大尺度环流背景。(2)低空偏西急流的长时间维持及加强,为暴雪区提供了丰富的水汽。强降水出现在中层强水汽辐合中心之后,低层水汽强辐合时。(3)双辐合—辐散结构的散度场特征,以及低层的辐合抬升,高层的辐散加强,为暴雪区提供了动力条件。(4)暴雪发生时大气处于稳定状态,但存在对称不稳定能量的释放。

Using conventional radiosonde and surface observations,as well as NCEP/NCAR 1 °× 1 ° reanalysis and other data,this study employed synoptic diagnosis to analyze the process of extreme snowfall that occurred in the Ili River Valley during 22-24 November 2022.The results indicate that:(1)The snowfall was located within a strong front area,with a short wave moving continuously eastward in the front area,providing the large-scale circulation background for the snowfall.(2)The long-term maintenance and strengthening of low-level westerly jets provided abundant water vapor for the blizzard area.Heavy precipitation occurred after the strong water vapor convergence center in the middle layer and the strong water vapor convergence in the lower layer.(3)The divergence field characteristics of the dual convergence-divergence structure,the convergence uplifting of the low layer,and the divergence strengthening of the high layer provided dynamic conditions for the blizzard area.(4)The atmosphere was in a stable state when the blizzard occurred,but there was the release of symmetric unstable energy.