Effect of anthropogenic emissions in East Asia on regional ozone levels during spring cold continental outbreaks near Taiwan: A case study

A numerical simulation study to quantify the effect of upstream transport and fossil-fuel and biomass-burning emissions from East Asia on the surface ozone near Taiwan has been performed based on data taken April 8–13, 2001, when a cold air outbreak occurred. The TAQM (Taiwan Air Quality Model) is employed in this study. Results show that, without considering emissions in East Asia, upstream transport of chemical species associated with the movement of the cold air mass increased the levels of CO and ozone near Taiwan from 75 to 180 ppbv, and 35 to 55 ppbv, respectively. Fossil-fuel and biomass-burning emissions can thus result in a significant increase of CO and ozone levels (70–150% and 50–100%, respectively) from the emissionless background. The most noteworthy phenomenon is that biomass burning in Eastern China alone can contribute up to 20% of the increase for these species, while the biomass burning in Southeast Asia has negligible influence.