Role of Heat Wave‐Induced Biogenic VOC Enhancements in Persistent Ozone Episodes Formation in Pearl River Delta

Abstract

Abstract Regional ozone (O 3 ) pollution is influenced by a combination of anthropogenic sources and biogenic volatile organic compounds (BVOC) emitted from vegetation. Under the influence of warming climate and projected expansion of urban green space, O 3 pollution may get worse, especially during heat waves (HWs). However, HW‐induced changes in BVOC and subsequent effects on regional O 3 pollution have not been adequately assessed. In this study, we used the Weather Research and Forecasting‐Community Multi‐scale Air Quality models to investigate the formation of a typical O 3 episode and quantify the O 3 response to BVOC in the Pearl River Delta during a HW in 2017. The results showed that the rate of increase of O 3 during the HW was 27.1 µg m −3 °C −1 , reflecting the rapid O 3 formation under high temperature. Compared with the non‐HW (NHW), gas‐phase chemistry and vertical transport were dominant contributors to O 3 formation. Sensitivity experiments indicate that the contribution of BVOC to ground‐level O 3 formation in Pearl River Delta was up to 42.1 μg m −3 because BVOC emissions in HW were 430 mol d −1 higher than the NHW. Under northerly winds and strong sea‐land breezes, BVOC and oxidation products from rural areas were transported to downwind VOC‐limited regimes and result in severe O 3 pollution owing to intense photochemical reactions and accumulated O 3 precursors. These findings point to the essential role of BVOC enhancements induced by HWs to O 3 formation and suggest the consideration of BVOC emission potential of planted trees in urban greening strategies for avoiding the offset effects from BVOC.