Influence of Mixed Air Pollution on Surface Micrometeorological Characteristics in Autumn and Winter in the Nanjing Area —Taking 2018 as an Example

Multielement observation data from the Station for Observing Regional Processes of the Earth System (SORPES) from 27 November to 3 December 2018 were used to quantitatively analyze the influence of mixed air pollution conditions on surface micrometeorological elements and energy balance characteristics under the combined effects of long-distance sand and dust and local emission pollution. On this basis, the response characteristics of surface meteorological elements and energy distribution under different pollution conditions in autumn and winter in Nanjing are compared by synthetic analysis. The results showed a daytime temperature of approximately 1 °C lower on polluted days than on clear days and a night temperature of approximately 2 °C higher. The downward/upward shortwave radiation flux on polluted days decreased as high as 48.8% and 55.2%, and the downward/upward long-wave radiation flux at night increased by 15% and 5.1%. On clear days, the net radiation budget during the day was 45.6% higher than that of polluted days, and the surface sensible heat flux was 75.5% higher than that of polluted days, while the difference in the surface latent heat flux was relatively small. The average Bowen ratio at night was higher on polluted days than on clear days, indicating stronger nighttime sensible heat exchange. The results help understand the influence process and mechanism of air pollution from different sources and different properties on surface energy balance and local meteorological elements in urban agglomerations of the Yangtze River Delta, as well as provide a verification basis for the interaction between air pollution and meteorological conditions, air quality prediction, and corresponding countermeasures.