Steve.Beauchamp@ec.gc.ca (1), D. Waugh (1), J. Bottenheim (2), A. Pinette (1), A. Gallant (2) and F. Hopper (2)

(1) Atmospheric Environment Branch, Environment Canada, 1496 Bedford Highway, Bedford, Nova Scotia, Canada. B4A 1E5.

(2) Atmospheric Environment Service, Environment Canada, 4095 Dufferin Street, Downsview, Ontario, Canada. M3H 5T4

Abstract:

Elevated surface ozone concentrations in the Atlantic region result primarily from the advection of ozone and precursors from heavily populated and industrialized emission source regions but are also influenced by regional anthropogenic and biogenic emissions. Thus, variations in both local and synoptic scale meteorology are important in determining surface ozone concentrations. During substantial periods of the 1996 NARSTO-CE study, meteorology in the Atlantic region was dominated by transient weather systems moving along a jet stream displaced more to the south than normal. This precluded the 3-4 days of warm, sunny conditions conducive to ozone build-up. Meteorological stations in the region reported above normal precipitation while maximum daily temperatures were below normal. Conditions in late June throughout July were typically cool and cloudy with showers which did not favor long range ozone and ozone precursor advection or photochemistry. Much of the 1996 ozone season was marked by a dominant northwestly circulation.