Trigger mechanism of a snow burst event in Northeast China  

东北一次雪飑事件的触发机制研究

作　　者：Baofeng Jiao Lingkun Ran Xinyong Shen Yanbin Qi 

机构地区：[1]Key Laboratory of Meteorological Disaster,Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science and Technology,Nanjing,China [2]Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing,China [3]Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai,China [4]Jilin Weather Modification Office,Changchun,China

出　　处：《Atmospheric and Oceanic Science Letters》2021年第2期13-20,共8页大气和海洋科学快报（英文版）

基　　金：supported by the Strategic Priority Research Program of the Chinese Academy of Sciences grant numbers XDA17010105and XDA20100304;the National Key Research and Development Program grant numbers 2018YFC1507104 and 2019YFC1510400;the Key Projects of Jilin Province Science and Technology Development Plan grant numbers 20180201035SF;the National Natural Science Foundation of China grant numbers 41775140 and 41790471。

摘　　要：A snow burst event characterized by brief heavy snowfall affected Northeast China and caused serious social impact on 26 January 2017,with the snowband generally aligned with a northeast–southwest-oriented cold front.ECMWF reanalysis data were used to diagnose the possible trigger mechanism.Results showed there were two stages:(a)an initial stage far away from the Changbai Mountains,and(b)an enhancement stage under the influence of high terrain.During the initial stage,the coupling of low-level frontogenesis and a favorable convergence pattern caused strong upward motion,contributing to the release of instability.When the snowband approached the high terrain during the enhancement stage,the various instabilities were triggered by the low-level frontogenesis,terrain circulation,and strong wind shear associated with the low-level jet.Further,a modified Q-vector divergence including generalized potential temperature was calculated to diagnose the vertical motion.It showed that the frontogenesis terms contributed greatly to the negative Q-vector divergence along the moist isentropes,while the pseudo-vorticity terms played a role in the regions with strong wind shear associated with the low-level jet in the warm section,suggesting both were important in stimulating the ascending motion.The regions with negative Q-vector divergence had a close relationship with the vertical structure of convection,indicating the potential to track the development of the snowband in the next few hours.2017年1月26日,中国东北地区发生了一次短时强降雪过程.本文利用ECMWF再分析数据诊断该过程的可能触发机制.分析表明,该过程可分两个阶段:初生阶段降雪远离高地形,低层锋生和有利的辐散场配置激发上升运动释放不稳定;增强阶段雪带接近长白山,低层锋生,地形环流以及与低空急流有关的风切变共同释放锋前不稳定.本文进一步计算了包含广义位温的修正Q矢量方程.结果表明,锋生项对沿湿等熵线的负Q矢量散度贡献较大,而拟涡度项在暖区强风切变区域中比较显著,两项在激发上升运动中同等重要.

关 键 词：Snow burst FRONTOGENESIS Q-vector 

分 类 号：P426.63[天文地球—大气科学及气象学]