A characterization of the detroit wintertime aerosol

The physical characterization of winter-time aerosol in the Detroit area studied over a 7-week period (January–March, 1983) is presented. Total suspended particle levels (<15 μm) were 56 ± 29 μg m^?3, with 66% of the material in the fine (<2.5 μm) particle fraction. Coarse and fine particle masses were reasonably correlated, indicating that local sources, not long-range transport, influenced winter-time aerosol at the site. Mobile sources were responsible for a marked diurnal variation in the nuclei mode particle count and accounted for about 10% of the submicron aerosol mass. Decreases in submicron aerosol concentrations during precipitation appear to be associated with advection of clean air into the area during frontal passage rather than to precipitation scavenging.