摘要
利用常规气象资料和NCEP CFSv2高分辨率(0.5°×0.5°)再分析资料,从天气形势、物理量场等方面分析了2018年1月4日豫西地区暴雪的产生机理。结果表明:这次暴雪属于典型的南支槽前西南急流配合地面东路冷空气共同作用的结果;中低层正涡度、高层负涡度,涡度带随高度向北倾斜,散度场上中低层辐合、高层辐散,这种配置有利于上升运动的发展和维持,为暴雪的产生提供了动力条件;中低层的水汽通量散度、上游水汽辐合区的强度和移动方向对降雪落区和强度预报有一定的指示意义;豫西上空有明显的锋生带自北向南移动,在南部的稳定维持有助于暴雪的产生,与暴雪带对应较好;锋生函数主要受水平散度项的影响,水平风场的辐合作用既有利于锋生,又有利于南方暖湿气流汇聚到暴雪区,暖湿气流沿锋面倾斜上升有助于暴雪的产生。
Using conventional observations and NCEP CFSv2 global 0.5°×0.5°final-analysis data,the circulation fea⁃ture and physical quantity field of a heavy snowfall event in Luoyang on January 3 in 2018 were analyzed.The results show that this heavy snowfall event in Luoyang belonged to typical transverse trough circulation background field,the conversion of transverse trough into perpendicular trough would guide cold airflow into Henan.The relative vorticity was positive in the middle-low troposphere and negative in the upper troposphere.The relative vorticity band tilted towards the north in the vertical direction.The vertical structure of convergence at low level and divergence in upper level caused to persist increase of ascending motion,thus provided dynamic condition for heavy snowfall.The mois⁃ture flux divergence field in the middle-low troposphere had better implications of the areas and strength of heavy snowfall.The frontogenesis band had moved from north to south over Luoyang,the stable maintenance of frontogene⁃sis in the south of Luoyang was conducive to the development of heavy snowfall.The frontogenesis band had a good prediction of the heavy snowfall areas.Frontogenesis function was mainly affected by the divergence term.The con⁃vergence of horizontal wind field was conducive to frontogenesis and moisture convergence,thus warmer and wetter airflow tilting upward along the front could be conducive to the development of heavy snowfall.
作者
许方璐
陈红霞
XU Fanglu;CHEN Hongxia(Luoyang Meteorological Bureau,Luoyang Henan 471000)
出处
《河南科技》
2020年第22期129-134,共6页
Henan Science and Technology
基金
河南省气象局预报员专项(KY201927)。
关键词
暴雪
西南急流
水汽通量散度
锋生函数
heavy snowfall
transverse trough
moisture flux divergence
frontogenesis function
