Aerometric studies in Greater Cincinnati using an integrating nephelometer

Horizontal and vertical scattering profiles are presented for Greater Cincinnati. The ground and upper air profiles were obtained from a nephelometer attached to a station wagon and a Cessna aircraft, respectively. Preliminary results show that under anticyclonic weather the dust dome is well pronounced with scattering coefficients of 8 × 10^-4 m^-1 (304 µg/m³) on the ground and 5 × 10^-4 m^-1 (190 µg/m³) at 900 m MSL. The most polluted city areas have about 2-2.5 × higher dust loadings than the outskirts. Under cyclonic weather the scattering profiles are flattened with values below 2 × 10^-4 m^-1 (76 µg/m³) both for surface and upper air samplings. The vertical profiles seem to indicate that Cincinnati's dust dome does not extend much beyond 1 000–1 500 m above the ground. Horizontal and meridional scattering profiles show that the nephelometer is well suited for monitoring small-scale changes in air pollutant concentrations due to changes in land use. The research has shown that in spite of inaccuracies in the assessment of absolute values, the instrument can provide valuable information on three-dimensional variations of particle concentrations.