一次攀西地区飑线天气过程形成机制分析

利用地面气象常规观测资料、区域自动站观测资料、雷达及卫星资料和NCEP 1°×1°的逐6h再分析资料,对2018年5月13日攀西地区南部的飑线天气过程的形成机制进行分析。结果表明:飑线发生在高空槽前,高空槽逐渐东移推动冷性气流沿背风坡东移,然后与前方低层暖空气汇合抬升形成对流;露点锋触发了飑线天气过程的形成;产生飑线天气区域的大气具有上干下湿、不稳定能量高、垂直风切变强、高层风速大和形成之前存在逆温层的特点;高空急流和动量下传对飑线的发生和加强具有促进作用;地形对飑线的形成和天气现象的分布有影响。

Formation Mechanisms of a Squall Line in Panxi Area

Using the data of surface meteorological observation, regional automatic meteorological station observation, radar and satellites, and NCEP 1°×1° 6 hour reanalysis, the formation mechanisms of a squall line weather process in the southern part of the Panxi area on 13 May 2018 is analyzed. The high altitude trough gradually moved eastward to push the cold airflow to the east along the leeward slope, and then merged with the low level warm air in front to form convection. The main trigger factor making the squall line weather process happen was the dew point front. The atmosphere around the squall line had the characteristics of dry at upper levels and wet at lower levels, high instability energy, strong vertical wind shear, large high level wind speed and the presence of an inversion layer before formation. The upper level jet stream and momentum downward transfer had a positive effect on the occurrence and strengthening of the squall line. The terrain had an effect on the formation of the squall line and the distribution of the weather phenomena.