2021年11月6—9日辽宁省极端暴雪过程诊断分析

Diagnosis and analysis of the extreme blizzard in Liaoning province from 6 to 9,November,2021

选用常规气象观测资料和NCEP 1°×1°再分析资料,对2021年11月6—9日辽宁省极端暴雪过程进行天气形势和物理量诊断分析。结果表明:此次极端暴雪过程主要受东北冷涡和强气旋共同影响,最大降雪量为80.8 mm,有20个站最大积雪深度超过30 cm。导致极端暴雪的主要原因是持续时间较长的强水汽输送和水汽辐合,最大值分别为18 g·hPa^(-1)·s^(-1)·cm^(-1)和-7×10-5 g·hPa^(-1)·cm^(-2)·s^(-1);异常偏强的低层辐合、高层辐散产生的强上升运动,中心值达到-3.0 Pa·s^(-1),对极端性暴雪预报有指示作用。斜压强迫和850 hPa强烈的水平锋生是此次极端降雪发生发展的重要机制。湿位涡MPV1>0且MPV2<0的配置表明,气旋性涡度及对称不稳定性的增大为暴雪过程的发生提供了有利条件。

Using the conventional meteorological observational data and 1°×1°reanalysis data from the NCEP(National Centers for Environmental Prediction),the weather situation and physical quantity diagnosis and analysis of the extreme blizzard process in Liaoning province from 6 to 9,November,2021 were carried out.The results show that the extreme blizzard process is mainly affected by the Northeast cold vortex and strong cyclone,the maximum snowfall is 80.8 mm,and the maximum snow depth measured at 20 stations exceeds 30 cm.The main cause of extreme blizzard is the long duration of strong water vapor transport and water vapor convergence,with the maximum values of 18 g·hPa^(-1)·s^(-1)·cm^(-1) and-7×10-5 g·hPa^(-1)·cm^(-2)·s^(-1),respectively.The strong ascending motion produced by abnormally strong convergence at the low level and divergence at the high level,with a central value of-3.0 Pa·s^(-1),is indicative of an extreme blizzard forecast.The baroclinic forcing and strong horizontal frontogenesis at 850 hPa are important mechanisms for the occurrence and development of this extreme snowfall event.The configuration of the moist potential vortex,with MPV1>0 and MPV2<0 indicates that the increase of cyclonic vorticity and symmetric instability provides favorable conditions for the occurrence of the blizzard process.