资源环境科技发展态势分析平台

The impact of urbanization-induced land-cover change and increase in anthropogenic emissions on the air quality of the megacity cluster of the Yangtze River Delta is investigated using the WRF-Chem model coupled with an urban canopy model at cloud-resolving resolution. The urban land-cover effect results in considerable reduction of near-surface aerosol concentrations over urban regions and an increase in particle concentrations at higher altitudes over the surrounding rural areas. The urban heat island effect increases the lower atmospheric instability and vertical velocity, thus increasing the planetary boundary layer height and ventilation over the urban area, favoring the dispersion of pollutants from urbanized areas to their immediate vicinities. However, the urbanization-induced increases in aerosol emissions outweigh that of land-cover change, resulting in a net increase in surface particle concentrations by up to 50 mu g m(-3) and the occurrence of winter haze by more than 10 d season(-1) in the Yangtze River Delta region.

Plain Language Summary Urbanization can significantly impact land-cover properties, surface heating, and emissions of air pollutants. China has experienced very rapid urbanization in the past few decades. Yangtze River Delta urban region became the largest megacity cluster in the world. In this study, we use an atmospheric model to examine how the urbanization-induced changes affect the air quality in the YRD urban and surrounding rural areas. Land-cover change and associated surface heating effect provide a favorable condition for moving pollutants out of Yangtze River Delta urban areas, but the increased pollutant emissions add even more, resulting in a net increase in the occurrence of winter haze. The number of days with very poor air quality increased by up to 10 days in each winter during 2000s, compared to 1970s.