摘要
利用NCEP再分析资料和常规观测资料,对2001年1月6日冀南暴雪过程进行分析。结果表明:偏南暖湿气流在东北南下的冷垫上爬升是降雪发生与维持的有利条件;暴雪过程以回流降雪为主,后期为西来槽降雪;暴雪发生时,有较强的上升运动和较大的水汽输送与辐合,高层辐散低层辐合、中低层正涡度的发展尤其是正涡度平流的增强为暴雪过程提供了动力条件;偏南风急流为暴雪区提供了充沛的水汽和能量;非地转湿Q矢量散度的辐合区与降雪区对应;低层高能舌的演变可以大致判断强降水出现的时间和位置;在回流降雪阶段出现对流性不稳定。
Based on the conventional meteorological data and reanalysis data from NCEP,the heavy snow process on January 6,2001 was analyzed.The results show that the south warm and humid airflow climbing along the southward cold air cushion is favorable to snowfall.Backflow snowfall is the main in this process,while snowfall from west trough is the main in the late of this process.It will have the strong ascending motion and plenty of water vapor transport and convergence when the heavy snow happens.The development of high level divergence and low level convergence together with positive vorticity in the middle and low level could provide dynamic conditions for the heavy snow,especially the concentration of positive vorticity advection.The southerly jet could afford abundant water vapor and energy for snowfall.Convergence area of ageostrophic wet Q-vector is accorded with snowfall area.Evolvement of the low level high energy tongue could determine the time and position of strong precipitation approximately.Convective instability appears at the stage of backflow snowfall.
出处
《气象与环境学报》
2010年第5期1-6,共6页
Journal of Meteorology and Environment
基金
国家自然科学基金项目(40875024
40875025
40875030
40775033
40405009)
气象灾害省部共建教育部重点实验室开放课题(KLME0905)
河北省自然科学基金项目(D2008001282)共同资助
关键词
暴雪过程
高空急流
上升运动
湿Q矢量
Heavy snow process
Upper level jet
Ascending motion
Wet Q-vector
