大气环流10~25 d振荡对佛山市冬半年空气质量的影响

Impacts of atmospheric 10-25-day oscillations on the air quality of Foshan in winter seasons

基于2016/2017年冬半年佛山市的空气质量数据以及大气环流资料,分析了它们的显著变化周期以及大气环流对空气质量的影响过程。结果表明:1)大气环流、空气质量指数及污染物浓度具有显著的10~25 d周期变化特征。地表气压的逐日变化超前空气质量指数及污染物浓度变化4~5 d,前者是空气质量潜在的预测因子。2)在冬半年,当东亚区域大气环流10~25 d分量的地表高压系统、低层的偏北风以及伴随的下沉运动自北向南及东南移动至华南地区,可使华南上空的大气层结较稳定,容易出现晴空少云天气,有利于大气污染物的光化学反应以及不利于污染物的扩散,从而导致污染物浓度升高及空气质量变差。3)当10~25 d分量的地表低压系统、低层的偏南风以及伴随的上升运动自北向南及东南移动至华南地区,则可使得华南的大气层结较不稳定,容易出现阴雨天气,有利于空气中污染物的净化和稀释,污染物浓度降低,空气质量变好。当南移的高压系统取代低压系统控制华南,则空气质量又开始变差。

This study investigates the dominant cycles of air pollutant concentrations and meteorologi‐cal elements and the influence of atmospheric circulation on air quality,based on the datasets of air quality and meteorological variables in the winter seasons of 2016/2017 in Foshan.The atmospheric variables,the air quality index,and the concentration of pollutants exhibit prominent 10-25-day oscillations.The surface air pressure shows a leading change 4-5 days ahead of the air quality index(AQI)and pollutant concentration,suggesting the former may be a potential predictor of air quality.In the winter seasons,as the surface high-pressure system,the northerly wind in the lower level layer and the accompanying sinking motion in 10-25-day components,move southward from north to South China,the atmospheric stratification over South China becomes more stable.Then,the clear sky and less cloud weather will easily appear,which is conducive to the photochemical reaction of atmospheric pol‐lutants and not conducive to the diffusion of pollutants,increasing pollutant concentration and the air quality becomes worse.In another case,as the 10-25-day components of the surface low-pressure sys‐tem,the southerly wind in the lower level and the accompanying upward motion move to South China from the north,the atmospheric stratification over South China will be more unstable and prone to cloudy or rainy weather,which is conducive to the purification and dilution of air pollutants.Then the concentration of pollutants will be reduced and the air quality will be improved.As the low-pressure system is replaced by the southward high-pressure system over South China,the air quality begins to deteriorate again.