STOSOS—A Study of Ozone in the Vancouver - Whistler -Pemberton Corridor

Observations of ozone concentrations along the Sea-to-Sky corridor (Vancouver – Whistler – Lillooet Lake) were made during the summer of 2003 as part of the Sea-to-Sky Ozone Study (STOSOS) designed to address air quality issues along this rapidly growing region of complex terrain. Central scientific issues of concern in this preliminary study were related to the potential for local photochemical ozone production, together with the extent to which the corridor is affected by regional scale transport (from the Lower Fraser Valley) and long range transport (possibly Trans-Pacific). Observations included a passive sampling network along the corridor (OGAWA samplers), routine monitoring with standard ozone instruments, aircraft measurements during a photochemical “episode”, and high altitude measurements at the top of Whistler Mountain (Whistler Peak). Passive sampler measurements were consistent with standard measurements and showed that highest average ozone concentrations (weekly) were found at the northeastern end of the corridor (Lillooet Lake). Localized 'peaks' in ozone concentrations were found in the communities of Squamish and Whistler. Aircraft observations on 29 July 2003 indicate that Whistler Peak measurements, at least at times, may be representative of a Mountain Convective Layer (as described by De Wekker) and not the free troposphere. This has important implications for the interpretation of the Whistler High Altitude site measurements. Highest hourly ozone concentrations at Whistler Peak during summer were ~70ppbv. These results have important implications for air quality management in the region.