Ring of impact from the mega-urbanization of Beijing between 2000 and 2009

The transient climate, soil, and air quality impacts of the rapid urbanization of Beijing between 2000 and 2009 are investigated with three-dimensional computer model simulations. The simulations integrate a new satellite data set for urban extent and a geolocated crowd-sourced data set for road surface area and consider differences only in urban land cover and its physical properties. The simulations account for changes in meteorologically driven natural emissions but do not include changes in anthropogenic emissions resulting from urbanization and road network variations. The astounding urbanization, which quadrupled Beijing urban extent between 2000 and 2009 in terms of physical infrastructure change, created a ring of impact that decreased surface albedo, increased ground and near-surface air temperatures, increased vertical turbulent kinetic energy, and decreased the near-surface relative humidity and wind speed. The meteorological changes alone decreased near-surface particulate matter, nitrogen oxides (NOx), and many other chemicals due to vertical dilution but increased near-surface ozone due to the higher temperature and lower NO. Vertical dilution and wind stagnation increased elevated pollution layers and column aerosol extinction. In sum, the ring of impact around Beijing may have increased urban heating, dried soil, mixed pollutants vertically, aggravated air stagnation, and increased near-surface oxidant pollution even before accounting for changes in anthropogenic emissions.