Mesoscale Air Quality under Stagnant Synoptic Cold Season Conditions in the Lake Powell Area

Mesoscale air quality under stagnant synoptic cold season conditions in the Lake Powell area is characterized through climatological, topographical and numerical studies. Using a synoptic climatological classification scheme, it is found that during the winter this region is dominated by stagnant conditions associated with slow-moving high pressure systems. Using topographic analyses, the Lake Powell area across S Utah and N Arizona can be regarded as a trapping basin which enhances pollution accumulation significantly under stagnant conditions. By applying a mesoscale meteorological model and a Lagrangian particle dispersion model, the dispersion characteristics of pollution from local sources are simulated for this situation. The results demonstrate the trapping and recirculation characteristics of the Lake Powell area for the commonly observed southwesterly synoptic flow just to the west of a surface polar high pressure system. Under such conditions during the winter, accumulation of pollution from local sources is expected to degrade the air quality in this region. Key word index: Mesoscale meteorological modeling, air quality, stagnant synoptic conditions, particle dispersion modeling, climatological classification, layered haze. I. INTRODUCfION quality to the prevalence of stagnant synoptic