The effects of anthropogenic heat fluxes on regional meteorology and air quality in typical city clusters of China

Anthropogenic heat (AH) can affect regional meteorology and air quality. The spatial distributions of AH fluxes in the typical city clusters of China are estimated. Moreover, in order to study their impacts on regional atmospheric environment, these heat fluxes are incorporated into the modified WRF/Chem with the seasonal and the diurnal variation. The modeling results show that AH fluxes over YRD and PRD have been growing in recent years. The high values of AH can reach 113.5 W/m² in YRD and 60 W/m² in PRD, respectively. AH fluxes can significantly change the urban meteorology. In YRD, 2-m air temperature (T₂) increases by 1.6 °С in January and 1.4°С in July, the planetary boundary layer height (PBLH) rises up by 140m in January and 160m in July, and 10-m wind speed (W₁₀) is intensified by 0.7 m/s in January and 0.5 m/s in July. More moisture can be transported to higher levels, and increase the accumulative precipitation by 15-30% in July of YRD. In PRD, T₂ rises up by 1.1°С in January and over 0.5°С in July, the PBLH increases by 120m in January and 90m in July, W₁₀ is enhanced over 0.35 m/s in January and 0.3 m/s in July, and the accumulative precipitation is intensified by 20-40% in July. These changes in meteorology can influence the distribution of air pollutants as well. Due to the increase of PBLH, surface wind speed and upward movement, the concentrations of primary air pollutants decrease near surface and increase at the upper layers over the cities. Chemical effects can play a significant role in ozone changes over the urban areas of YRD, so ozone concentrations increase at surface and decrease at the upper layers. In PRD cities, however, the chemical effects play a significant role in ozone changes in winter, while the vertical movement can be the dominant effect in summer. Thus, ozone concentrations in big cities increase in January, but decrease at the lower layers and increase at the upper layers in July. In all, AH fluxes should not be ignored in urban meteorology and air quality assessments.