A Model Study of the Impact of Uncertainty in the Heterogeneous Uptake Coefficients on Dust Aerosol Surface

The heterogeneous uptake coefficients (γ) taken from recent laboratory studies are analyzed in terms of aerosol sample, experiment method, and analysis method. The reference γ which are theoretically more suitable for Asian dust aerosol are derived and applied in a regional air quality model to represent heterogeneous reactions of dust aerosol in East Asia. In order to explore the sensitivity of model results to γ values, two sensitivity experiments, namely T-up (upper limit) and T-low (lower limit), are conducted based on the upper and lower limits of γ values for four gaseous species (HNO3, N2O5, O3, and SO2). T-rh experiment is also conducted to investigate the influence of relative humidity on γ values for HNO3 and N2O5. Model results using referenceγvalues are generally better than those using upper and lower limits of γ values in comparison with observations. This study also shows that it would be more reasonable to take γ as a function of relative humidity than to take it as a constant. Through heterogeneous reactions, dust aerosol can make the average concentrations of SO2, NOx, and O3 decrease by 3.44%, 5.92%, and 1.75%, respectively, while those of sulfate and nitrate increase by 5.22% and 23.25% below 3 km within the model domain, showing heterogeneous reactions exert more influence on aerosols than gases. The percentages could be changed when using different γ values, especially ozone and nitrate. The model results of ozone and nitrate can differ by 13.4% and 10.1% between T-up and T-low.