Updating Biogenic Volatile Organic Compound (BVOC) Emissions With Locally Measured Emission Factors in South China and the Effect on Modeled Ozone and Secondary Organic Aerosol Production

Biogenic volatile organic compounds (BVOCs) emitted from terrestrial plants contribute substantially to ozone (O3) and secondary organic aerosol (SOA) formation in the troposphere. Accurate estimation of BVOC emissions is highly challengeable with a variety of uncertainties, one of which is the use of default emission factors (EFs) particularly for underrepresented regions without local data. In this study, locally measured BVOC‐EFs in south China, a subtropical region with abundant vegetation, were used to update regional BVOC emissions as estimated by the Model of Emissions of Gases and Aerosols from Nature (MEGAN). These EFs were recently determined in situ with characterized dynamic chambers for the emissions of isoprene, monoterpenes, and sesquiterpenes from tree species. The Community Multiscale Air Quality (CMAQ) model was then employed to see how much the regional O3 and SOA production is altered with the updated BVOC emissions. Results revealed lower BVOC emission estimates in south China when using the localized EFs than the MEGAN default ones, particularly for sesquiterpenes with a notable average reduction rate of approximately 40%. Using the updated BVOC emissions improved model O3 predictions in all seasons when compared to surface O3 monitoring, yet the lower BVOC emissions resulted in modeled O3 and SOA concentrations decreased by up to −6 ppb and −1.5 μg m−3, respectively, throughout south China. This study highlights the significance of localized EFs in refining emission estimates and air quality predictions in regions with a wealth of vegetation. Plain Language Summary Terrestrial plants can emit a variety of biogenic volatile organic compounds (BVOCs), such as isoprene and terpenes. These BVOCs significantly impact tropospheric ozone (O3) and secondary organic aerosol (SOA) formation, and therefore accurate BVOC emission estimates are crucial for air quality modeling particularly in regions with a wealth of vegetation. However, in many regions local BVOC emission factors (EFs) are unavailable and using the model default EFs may bias the regional BVOC emissions. Here we carried out in situ measurements of EFs with well characterized dynamic chambers in south China. With these local EFs, the BVOC emissions was estimated by the MEGAN model, revealing a reduction in BVOC emissions in south China than those using the default EFs. When compared the modeling results with those from surface monitoring network, model performance in the predictio