| Summary: | A fast response chemiluminescent ozone sonde originally intended for use as a
balloon borne instrument, was deployed on a single engine light aircraft to determine
mean ozone concentrations in the boundary layer downwind of a major urban centre.
Vancouver is a coastal city at the mouth of a major river delta and valley walled in by
mountains to the north and east. Hence, the pollutant distribution during anti-cyclonic
conditions is influenced by the thermally induced flows of the sea/land breeze and
mountain/valley wind systems. This study focused on ozone concentration in a steep
walled, glacial valley near the city, where ozone concentrations had not been previously
monitored but were suspected to be high. Measurements confirmed this hypothesis and
the mass budget of ozone for the valley was calculated for a period shortly after sunrise
when the rate of boundary layer growth was at its maximum. The high levels of ozone
found in the valley were partly attributed to residual layer storage of ozone above the
nocturnal stable layer. This overnight storage of ozone during sustained anti-cyclonic
conditions suggests that the Pitt River valley and possibly other tributary valleys
represent an important net sink for ozone emanating from precursor sources in the Lower
Fraser Valley. === Science, Faculty of === Earth, Ocean and Atmospheric Sciences, Department of === Graduate
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