A numerical study of the impact of climate and emission changes on surface ozone over South China in autumn time in 2000-2050

Abstract Using the Weather Research and Forecasting Model with Chemistry (WRF/Chem) model, we conducted a series of numerical experiments to investigate the relative contributions of climate and emission change to surface ozone (O 3 ) over South China for the period of October in 2005–2007 and 2055–57. WRF/Chem was driven by the outputs of Community Climate System Model version 3 (CCSM3). The simulations predict that on average near-surface temperature and water vapor mixing ratio are projected to increase 1.6 °C and 1.6 g kg − 1 under A1B scenario. In response to the climate change, the emissions of isoprene and monoterpenes in South China increase by 5–55% and 5–40%, respectively. The change of climate and biogenic emission can result in a change of −5 to 5 ppb of afternoon surface O 3 mixing ratios, with an average of 1.6 ppb over the land region in South China. Over Pearl River Delta, a region of dense network of cities, the 2000–2050 climate changes increase afternoon mean surface O 3 by 1.5 ppb. The change of anthropogenic emission can result in a change of −3–24 ppb of afternoon surface O 3 mixing ratios, with an average of 12.8 ppb over the land region in South China. Our analysis suggests that the anthropogenic emissions have greater impact on the change of surface O 3 concentration over South China compared to climate change. The combined effect of climate and emission can increase afternoon mean surface O 3 over South China by an average of 18.2 ppb in the land region, with the highest increase up to 24 ppb occurring over southeast of Hunan province.