Assessment of the Contribution of Traffic Emissions tothe Mobile Vehicle Measured PM2.5 Concentration byMeans of WRF-CMAQ Simulations

The Alaska adapted version of the Weather Research and Forecasting and the Community Modeling and Analysis Quality (WRF-CMAQ) modeling systems was used to assess the contribution of traffic to the PM2.5-concentration in the Fairbanks nonattainment area and to develop an algorithm to interpolate mobile measurements into areas without any observations. Simulations were performed with WRF-CMAQ with and without consideration of traffic emission for two episodes in winter 2009/10 and 2010/11. Comparison of the simulation results with observations showed that the Alaska adapted WRF-CMAQ has relatively good performance in simulating meteorological quantities and PM2.5-concentrations. Comparison of the simulations with and without consideration of traffic emissions revealed that emissions from traffic contributed to about 10% on average to the total PM2.5-concentration in the Fairbanks nonattainment area during the two episodes. The interpolation algorithm was developed based on the WRF-CMAQ results of the first episode and its performance was demonstrated by the results of the second episode. The algorithm can be used in the future to produce spatial distributions of PM2.5-concentrations over the nonattainment area based on the limited observation made by the instrumented vehicle. The interpolated distributions can be visualized and put onto the web to serve as a tool to provide spatially differentiated air quality advisory to the public.