Application of the Urban Airshed Model in the Fraser Valley of British Columia, Canada and Implications to Local Ozone Control Strategies

Abstract

The Fraser Valley in the southwestern province of British Columbia, Canada is one of Canada’s highest ozone concentration areas where the National Ambient Air Quality Objective of 82 ppb per hour is exceeded several times a year under high pressure ridge conditions (Taylor, 1991; McKendry, 1994). Modeling efforts are aimed at supporting local regulatory agencies in their attempt to apply appropriate control strategies to the problem. The complex nature of the Fraser Valley offers a modeling challenge. The irregular terrain (Figure 1) generates complex mesoscale flows and modeling is further complicated by changing land use from the urban centre of Vancouver in the west to agricultural farmland in the east. Located on the east coast of the Pacific Ocean, the area is not influenced by upstream transport and thus provides a unique closed system in which to assess and verify model behavior.