达州一次持续性雾霾过程特征及成因分析

Characteristics and Cause Analysis of a Persistent Haze Process in Dazhou

利用达州污染物浓度资料,结合常规气象观测资料和ERA5再分析资料,分析2023年1月达州一次持续雾霾的特征和成因。结果表明:(1)前期高空纬向环流、低层弱暖平流和地面均压场的配置为雾霾天气的形成和维持提供了有利的环流背景;后期南支槽活跃,水汽条件转好,出现弱降水,有利大雾或浓雾维持及污染物累积,霾减弱消失。(2)边界层逆温是本次雾霾过程的重要特征,雾霾的形成和维持与逆温强度(尤其是双层强逆温)呈正相关;湿层厚度大有利于大雾或浓雾维持及污染物颗粒吸湿增长,但不利于霾维持。(3)弱风条件、低层弱的负涡度(或0涡度)和边界层微弱的湍流运动均有利于雾霾的形成和维持。

Using the conventional meteorological data,ERA5 reanalysis data,and pollutant concentration data,the characteristics and causes of a sustained haze in Dazhou in January 2023 were analyzed.The results showed that:(1)The configuration of high-altitude meridional circulation,low-level weak warm advection,and ground pressure field in the early stage provided favorable circulation background for the formation and maintenance of haze weather.In the later stage,the southern trough became active,the water vapor conditions improved,and there was weak precipitation,which was conducive to the maintenance of heavy fog or fog and the accumulation of pollutants,and the haze weakened and disappeared.(2)The boundary layer inversion was an important feature of the haze process,and the formation and maintenance of haze were positively correlated with the inversion intensity(especially the double-layer strong inversion).The high wet layer thickness was beneficial for maintaining heavy fog or fog and increasing the moisture absorption of pollutant particles,but was not conducive to maintaining haze.(3)Weak wind conditions,weak negative vorticity(or zero vorticity)in the lower layers,and weak turbulent motion in the boundary layer were conducive to the formation and maintenance of haze.