A Study of the Influence of Terrain on Fog Development

Abstract

A general purpose mesoscale numerical weather prediction model is used to simulate the development of fog at Perth, Western Australia, on 27 April 1990. Using one-dimensional and two-dimensional model configurations, an attempt is made to identify the important processes involved. It is proposed that fog forms with an onshore wind when cold air drainage from the plateau to the east creates a stagnation point in the near surface flow on the coastal plain. A full model integration with time-dependent boundary conditions supports this but shows an along-coast variation associated with valleys that dissect the edge of the plateau. It is concluded that in uneven terrain the development of local nocturnal winds may frequently determine the location and timing of fog formation.