Meteorological Modeling on High-Ozone Days in Perth, Western Australia

Abstract

The West Australian capital city of Perth is located on a coastal plain between the sea to the west and an escarpment rising to the east. It is isolated from all other cities or sources of pollution. In this study, the meteorological conditions leading to high ozone levels have been classified according to the dominant weather patterns using both synoptic charts and air monitoring data. The data revealed that practically all high-ozone days were associated with recirculation of ozone or its precursors. Meteorological modeling was then performed for the generic conditions leading to high ozone in the Perth region. The modeling predicted that recirculation of surface air over the Perth region was common. Both same-day and next-day recirculation of surface air are features of the model predictions and are conducive to high ozone levels. The modeling predicts day-by-day buildup of smog to be a favored occurrence under these synoptic conditions. Other interesting meteorological features seen in Perth observations on high-ozone days were also predicted by the modeling, including stalling sea breezes under some conditions, hydraulic jump effects over the escarpment, and mesoscale enhancement of the west coast trough.