AN ANALYSIS OF THE METEOROLOGICAL PARAMETERS AFFECTING AMBIENT CONCENTRATIONS OF ACID AEROSOLS IN UNIONTOWN, PENNSYLVANIA

Ambient concentrations of aerosol strong acidity (H+) that were collec ted in Uniontown, Pennsylvania, during the summer of 1990 were evaluat ed to determine the relationships between meteorology and the magnitud e of the H+ concentrations. An extensive database containing 17 meteor ological parameters was compiled for the Uniontown - Pittsburgh region . The database included both surface and upper air meteorological para meters. Concentrations of ambient acid sulfate aerosols collected in U niontown, Pennsylvania, in the summer of 1990 were greatly affected by both local and regional meteorological conditions. Seven distinct met eorological synoptic types or regimes were identified for the summer m onths. A clear association was shown between episodic events of elevat ed ambient H+ concentrations and one of the regimes, referred to here as synoptic type 5, which occurred when an anticyclone set up to the e ast of the mid-Atlantic states. Much of the variability (approximately 45%) in H+ concentrations for the overall model was explained by the surface air temperature. Approximately 10% of the H+ variability was e xplained by westerly winds as expressed by the U components of the mor ning 850 mb wind and the mean daily surface wind at Uniontown. Results showed that for days under the influence of synoptic type 5, which wa s associated with the highest levels of ambient H+, the surface temper ature explained approximately one-third of the variability in H+ conce ntrations. The height of the mixing layer also affected the variabilit y in H+ concentrations, accounting for nearly a quarter of the varianc e. These results show that an analysis of the surface wind speed and d irection alone will not adequately explain the variability in the conc entrations of ambient acid aerosols. Analyses of the meteorological pa rameters affecting ambient concentrations of acid aerosols should incl ude the mixing height, as well as the temperature, wind speed, and win d direction; both at the surface and for an upper level of the atmosph ere that facilitates regional transport of pollutants. Copyright (C) 1 996 Elsevier Science Ltd