Recirculation of coastal urban air pollution under a synoptic scale thermal trough in Perth, Western Australia

Air pollutant recirculation is a common feature of coastal cities as a result of the diurnal variation of the land/sea breeze circulation. On the western coast of Australia, a thermally induced synoptic scale trough interacts with this local circulation to enhance the sea breeze flow, allowing pollutant to penetrate further inland. As well a low wind speed zone formed offshore near the trough axis leads to increased ozone concentrations and the rotation of the trough axis during its onshore movement spreads these higher concentrations of air pollutant over a larger area.