Changes in summer biogenic volatile organic compound emission and secondary organic aerosols over the 2001–2018 period over China: Roles of leaf biomass, meteorology, and anthropogenic emission variability

A regional air quality model system (RAQMS), coupled with a biogenic emission model was applied to investigate the variations of summertime biogenic volatile organic compound (BVOC) emission and secondary organic aerosols (SOA) during 2001–2018 over China. During 2001–2018, evident land use changes occurred, especially in the Sichuan Basin, the Qinling Mountains, and the megacities over east China. Leaf aera index (LAI) increased significantly over the western parts of northeast China, the Qinling Mountains, the North China Plain (NCP), and most areas of south China. The domain-average LAI and BVOC emission increased by 0.2 m 2 m −2 (19%) and 3.0 Tg (26%), respectively, over China during 2001–2018, mainly due to the increases in LAI and air temperature. It is found that near surface BSOA concentration increased apparently over China from 2001 to 2018, with the maximum increment exceeded 2 μg m −3 (75%) in the middle reaches of the Yangtze River. The domain-average surface BSOA concentration increased remarkably by 0.44 μg m −3 (41%) over China, resulting from the combined effect of LAI and anthropogenic emission increases, and meteorological change, in which the land use and LAI changes were the dominant driving factors, explaining over 50% of the BSOA increase, while the changes in meteorology and anthropogenic emission contributed almost equally to the remaining BSOA increase. The changes in near surface BSOA concentration (μg m −3 ) between summer 2001 and 2018 due to (a) land use and LAI changes; (b) meteorology change; (c) anthropogenic emission change; (d) all the above factor changes. • Summer BVOC emissions and BSOA concentration over China during 2001–2018 are explored. • The domain-average LAI increased by 0.2 m 2 m −2 (19%) over China from 2001 to 2018. • BVOC emissions in China increased by 3.0Tg (26%) due to increased LAI and air temperature. • BSOA concentration increased by 0.4 μg m −3 (41%) due to land use, meteorology, and anthropogenic emission variability.