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 (O3) 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 O3 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 O3 by 1.5 ppb. The change of anthropogenic emission can result in a change of -3-24 ppb of afternoon surface O3 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 O3 concentration over South China compared to climate change. The combined effect of climate and emission can increase afternoon mean surface O3 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.