Attribution of Meteorological Variability, Land-Cover/LAI Change, and O3-Induced Stomatal Regulation to Summer Biogenic VOC Emissions in China during 2013-2023.
Abstract
Biogenic volatile organic compounds (BVOCs) strongly influence atmospheric oxidation capacity, ozone (O3) formation, and secondary organic aerosol production. In China, BVOC emissions are being reshaped by concurrent meteorological variability, land-cover changes, and increasing surface O3 pollution, yet their relative contributions remain unclear. Here, we developed an improved WRF-MCIP-BEIS modeling framework incorporating O3-induced stomatal regulation through the canopy energy-balance pathway, and integrated O3-on/O3-off experiments, factorial scenarios, and Shapley decomposition to attribute summer BVOC emission changes across China during 2013-2023. BVOC emissions exhibited strong regional heterogeneity, with relatively high summer emissions occurring in Southwest China (2019.3 kt summer-1), East China (1601.4 kt summer-1), and South China (1223.6 kt summer-1). O3-induced stomatal regulation consistently enhanced summer BVOC emissions, increasing national total emissions by 17.9 kt summer-1 in 2013 and 29.1 kt summer-1 in 2023, although the relative effect remained modest (0.20-0.31%). Species-level responses were more pronounced: isoprene showed the strongest sensitivity to O3-induced stomatal regulation, with relative increases of 0.36-0.55%, approximately two to three times larger than those of other BVOC groups. Shapley decomposition revealed that BVOC emission changes were primarily governed by competing meteorological and land-cover/LAI effects, with national mean contributions of approximately -558.0 and +454.3 kt summer-1, respectively, whereas O3-induced stomatal regulation accounted for a much smaller but systematic positive scenario-based contribution (+7.6 kt summer-1). These findings demonstrate that O3-induced stomatal regulation introduces a modest but chemically relevant vegetation feedback through the canopy energy-balance pathway, while meteorological variability and land-cover/LAI changes remain the dominant controls on long-term summer BVOC variability.