The impact of biogenic emissions on ozone formation in the Yangtze River Delta region based on MEGANv3.1

Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry due to their large quantities and high reactivity. In this study, the impacts of BVOC emissions on ozone formation were investigated based on MEGANv3.1 in the Yangtze River Delta (YRD) region, which has increasingly suffered from ozone pollution in recent years. The sensitivities of BVOC emissions to different drought stress configurations and the quality of emission factors were evaluated. Furthermore, BVOC contribution to ozone formation was simulated by integrated meteorology and air quality model system and the impacts of different BVOC emission scenarios on ozone concentration were discussed. Annual BVOC emissions estimated with the default drought stress configuration (i.e., base case) was 6.8 × 105 tons. The drought stress algorithm implemented in MEGANv3.1 could suppress BVOC emissions by 58% and this algorithm was sensitive to the choice of wilting point values. The BVOC contribution to the average of daily maximum 8 h ozone concentration without drought stress effect in July 2016 was 104% higher than that in the base scenario when the drought stress effect is activated. Using an alternative set of wilting point led to BVOC contribution being 48% higher than that in the base scenario. High contributions of BVOCs to simulated ozone concentration were found in northern Zhejiang, especially in Hangzhou and its surrounding areas.