Role of Anthropogenic Volatile Organic Compounds and Nitrogen Oxides as Ozone Precursors in the Wintertime over East Asia

As an exercise in model sensitivity, the Models-3 Community Multiscale Air Quality (CMAQ) modeling system with meteorological fields from the Regional Atmospheric Modeling System (RAMS) was applied to study the response of photochemical oxidants to systematic increases in anthropogenic volatile organic compounds (VOC) and nitrogen oxides (NOχ) emissions in January 1997 over East Asia. Three simulations-one base case and two sensitivity simulations were carried out. Two sensitivity simulations were performed by assuming a 35% separate increase in anthropogenic VOC and NOχ emissions comparing with the base case. Biogenic VOC emissions were held constant across the sensitivity simulations. To evaluate the model performance, ozone mixing ratios (O3) from the base case simulation were compared with surface observations at five remote sites in Japan, and it was found that the model reproduces most of the important features in the observations. Monthly average O3 concentrations in the daytime were examined to gain an understanding of how the increase in anthropogenic emissions affected the overall chemical system for each sensitivity simulation.