Implementation of road and soil dust emission parameterizations in the aerosol model CAMx: Applications over the greater Athens urban area affected by natural sources

Abstract

A detailed dust emission parameterization was developed for aerosol production by human and natural activity. The road dust scheme includes tire wear, break wear, road abrasion and vehicle-induced re-suspension. The natural dust scheme includes wind (Aeolian) erosion from soil surfaces and land disturbances, and considers the effects of soil and atmospheric parameters on dust productivity. Emission rates are chemically and size-resolved and are incorporated in the CAMx aerosol model coupled with the ISORROPIA II inorganic module. Emissions and concentrations are predicted for five simulation periods, using a domain covering Greece with a fine mesh over the greater Athens area. Re-suspended mass is the main dust component, calculated 4-5 times higher than exhaust emissions. Soil dust emissions are much greater than road dust during high winds but are of less importance inside the city with maximums located at the periphery of the urban core. Comparison with observations suggests that the road dust component seems adequately estimated in traffic-affected areas and accounts for 15-40% of the total PM 10. Calcium, regarded as a soil dust tracer, is calculated to be 2-4 μg m -3 in areas with high Aeolian emission rates, similar to measured values. Sodium and magnesium predictions show their marine origin, and reasonably replicate the observed mass and size distribution during well-established onshore flows. Nitrates are predicted as measured during lower winds, but are underestimated when stronger winds prevail from the west. This is caused by an overestimated industrial influence of Athens. As a result, ammonia is bound to the excess of sulfate, rather than reacting with nitric acid. Secondary species are influenced slightly by heterogeneous chemistry on dust particles. © Copyright 2010 by the American Geophysical Union.