Impacts of land use and land cover change on regional meteorology and air quality over the Beijing-Tianjin-Hebei region, China

摘要

The land use and land cover (LULC) change can modulate regional meteorology and consequently influence the air quality. This study incorporates two types of LULC data (representing early 1990s and most recent years respectively) into the Weather Research and Forecasting Model-Community Multiscale Air Quality (WRF-CMAQ) model to investigate the impacts of LULC change on the meteorology and air quality. The LULC change and associated parameters including land cover proportion, land surface albedo, roughness length result in some variations of surface energy balance, surface temperature, planetary boundary layer height (PBLH), surface wind speed and direction, which lead to domain-wide increases of 2-m temperature (T2) (0.53–0.96 °C, 3.6–14.9%), PBLH (3.3–130 m, 3.5–38.3%) and decrease of 10-m wind speed (WS10) (0.12–0.47 m/s, 5.2–15.7%) in the urban. As a result, the concentrations of air pollutants are also affected by LULC change. It leads to a domain-wide decrease of PM2.5in the urban. The reductions are more obvious during the rush hour in the morning and evening. The impacts of LULC change on O3vary in different seasons and cities. In Beijing, O3increases by 0.5–4.3 ppb during daytime in July. While in Tianjin, O3decreases by up to 3.4  ppb at noon. In summer, the change of O3is inversely corresponding to NOxchange, which may be associated with the VOC-limited O3chemistry in daytime and NOxtitration at night in the urban. In winter, the change of O3is mainly related to the reduced radiation which is unfavorable for O3formation. Meanwhile, these changes of PM2.5and O3are different under variable levels of air pollution. The largest reduction ratio of PM2.5occurs at slightly-heavily polluted levels instead of severely polluted level, while the extent of O3increase becomes greater along with the aggravation of O3pollution.