Abstract:
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.