VERTICAL PROFILES OF OZONE DURING THE EMEFS-I EXPERIMENT IN SOUTHERN ONTARIO

Vertical profiles of ozone from the surface to over 15 km altitude wer e obtained with a combination of free-flying and tethered ozonesondes and differential absorption lidar. During the Eulerian Model Evaluatio n Field Study (EMEFS I) of July-August 1988, these profiles were compa red with the output of a sophisticated regional-scale three-dimensiona l Eulerian dispersion and chemistry model, the Acid Deposition and Oxi dant Model (ADOM). The results show that ADOM predicts the ozone conce ntration profiles with accuracy only in the lower troposphere and part icularly well during simple synoptic situations. In the upper troposph ere, the model does not predict the intrusions of ozone from the strat osphere which appear to be extremely important in determining the ston e concentration profiler.