Research on the impact of land use and land cover changes on local meteorological conditions and surface ozone in the north China plain from 2001 to 2020.

Land use and land cover changes (LULCC) alter local surface attributes, thereby modifying energy balance and material exchanges, ultimately impacting meteorological parameters and air quality. The North China Plain (NCP) has undergone rapid urbanization in recent decades, leading to dramatic changes in land use and land cover. This study utilizes the 2020 land use and land cover data obtained from the MODIS satellite to replace the default 2001 data in the Weather Research and Forecasting-Community Multiscale Air Quality (WRF-CMAQ) model. It simulates and analyzes the direct impact of LULCC on meteorological parameters and the indirect impact on surface ozone (O) concentration through physical and chemical processes in the North China Plain during July in the summer. Six rapidly urbanizing cities were selected to represent the North China Plain. The results show that LULCC significantly increased sensible heat flux and 2-m temperature in rapidly urbanizing areas throughout the diurnal cycle, with more pronounced effects during the daytime, ranging from 6.49 to 23.46 W/m and 0.20-0.59 °C, respectively. The 10-m wind speed decreased at night and increased during the day, with changes ranging from - 0.43 to 0.27 m/s at night and - 0.16 to 0.15 m/s during the day. The planetary boundary layer height generally increased, with a larger rise during the daytime, ranging from 23.63 to 84.74 m. Simultaneously, surface O concentrations increased during both daytime and nighttime. The daytime increase ranged from 2.89 to 9.82 μg/m, while the nighttime increase ranged from 1.76 to 7.77 μg/m. LULCC enhanced meteorological and chemical processes as well as vertical transport, leading to an increase in O. At the same time, it reduced the increase in O through horizontal transport and dry deposition processes. These changes are related to the meteorological variations. The impact on O concentrations was not limited to the surface but extended to the top of the planetary boundary layer (approximately 1500 m). Below 500 m, vertical transport increased O concentrations, while horizontal transport decreased O concentrations. Additionally, the meteorological and chemical processes induced by LULCC showed enhanced effects above the surface, whereas the dry deposition process had a smaller impact on O concentrations above the surface. This study reveals the significant impact of urban expansion on regional meteorological parameters and air quality. It optimizes the model's simulation of regional air quality and provides new insights into understanding the effects of urbanization on meteorological conditions and air quality.