四川盆地南部一次持续性雾霾过程的特征及成因分析

本文利用常规气象资料、NCEP (1°×1°)再分析资料和环监站实时监测数据,分析了2017年12月四川盆地南部一次持续性雾霾的气象特征和增强机制。结果表明:(1)中高纬平直纬向环流、低层弱偏南偏东气流、地面均压场组成的静稳天气长时间维持为雾霾天气的形成和维持提供了有利的环流背景条件。(2)上干下湿、逆温明显的大气稳定层结,连续无降水、近地层高湿和较弱的风场提供有利的气象要素条件。(3)低层弱冷平流、上层暖平流促进稳定层结长时间维持和近地层水汽凝结作用加强,为雾霾天气的增强和持续起到了重要作用。(4)冷空气、降水,水平和垂直扩散能力增强是空气污染物浓度降低的重要条件。 

Characteristics and Cause Analysis of a Persistent Haze Process in Southern Sichuan Basin

By using regular meteorological data, reanalysis data of NCEP 1°×1°, environmental monitoring data, the article discusses the persistent haze in southern Sichuan Basin in December 2017. The findings are follows: Firstly, the zonal circulation in the mid-high latitude is straight; the low level is the weak eastward and southward wind; the Sichuan Basin is located in the lower pressure of the ground. The long-term stable weather situation provides favorable circumfluence background condition for fog and haze. Secondly, upper-layer is dry and lower-layer is wet. The temperature inversion character is obvious.No rainfall, the high relative humidity and weak wind provide the favorable meteorological conditions. Thirdly, the low-level cold advection and upper-level warm advection are favorable for long-term maintenance of stable stratification and condensation of water vapor in surface layer, which play an important role in enhancing and sustaining fog and haze weather. Fourthly, the cold air, the precipitation, and the enhancement of horizontal and vertical diffusivity are important conditions for reducing the concentration of air pollutants.