Abstract
An analysis of mesoscale influences on ground level wind fields indicates that topography and the thermal cells associated with mesoscale ground temperature anomalies (urban heat islands and land-water contrasts) are the major determinors of horizontal trajectory perturbations on scales appropriate for air pollution analyses. Simple analyses based on the divergence equation permit calculations of wind fields for air pollution trajectories that appear much more realistic than conventional objective analysis of surface wind observations. The analysis provides a unique objective procedure for real-time integration of the conservation of pollutant equation or for the development of regional air pollution climatology.