Industrial Dry Heat\nIsland and Dispersion of Air Pollutants\nInduced by Large Coal-Fired Activities

Notable anthropogenic heat sources such as coal-fired\nplants can\nalter the atmospheric boundary layer structure and the pollutant dispersion,\nthereby affecting the local environment and microclimate. Herein,\nin situ measurements inside a coal-fired steel plant were performed\nby multiple advanced lidars from 21 May to 21 June of 2021 in Yuncheng,\nShanxi Province, China. Comparing with an adjacent meteorological\nsite, we found a prominent nighttime dry heat island overhead of the\nfactory, which was 3–10 °C hotter and 30%–60% drier\nthan the surrounding fields. Large-eddy simulations constrained by\nthe measured thermal contrast suggested that the heat-island-induced\ncirculation could upward transport factory-discharged pollutants and\nhorizontally spread them below the residual layer top, forming a mushroom-shaped\ncloud. The shape, size, and pollutant loading of the cloud were highly\ndetermined by thermodynamic variables such as aerodynamic wind and\nanthropogenic heat flux. Furthermore, these retained residual-layer\npollutants can be convected downward to the ground after sunrise through\nthe fumigation effect, causing the peaking phenomena aboveground.\nThese peaks were statistically evidenced to be common in major urban\nagglomerations in China. The study provides a new insight regarding\nthe origins of residual-layer pollutants and highlights the needs\nfor programming representations of coal-fired heat emissions in mesoscale\nair-quality models.