This study investigated the impacts of seasonal andregional variability in biogenic volatile organic compounds (BVOCs) onsurface ozone over the Pearl River delta (PRD) region in southern China in2010 with the WRF–Chem/MEGAN (Weather Research and Forecasting coupled with Chemistry/Model of Emissions of Gases andAerosols from Nature) modeling system. Compared to observations inthe literature and this study, MEGAN tends to predict reasonable BVOCemissions in summer, but may overestimate isoprene emissions in autumn, evenwhen the local high-resolution land-cover data and observed emission factorsof BVOCs from local plant species are combined to constrain the MEGAN BVOCemissions model. With the standard MEGAN output, it is shown that the impactof BVOC emissions on the surface ozone peak is ~3 ppb onaverage with a maximum of 24.8 ppb over the PRD region in autumn, while theimpact is ~10 ppb on average, with a maximum value of 34.0 ppbin summer. The areas where surface ozone is sensitive to BVOC emissions aredifferent in autumn and in summer, which is primarily due to the change ofprevailing wind over the PRD; nevertheless, in both autumn and summer, the surface ozone is most sensitive to theBVOC emissions in the urban area because the areais usually VOC-limited. Three additional experiments concerning thesensitivity of surface ozone to MEGAN input variables were also performed toassess the sensitivity of surface ozone to MEGAN drivers, and the resultsreveal that land cover and emission factors of BVOCs are the most importantdrivers and have large impacts on the predicted surface ozone.
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