A STUDY OF THE INFLUENCE OF TERRAIN ON FOG DEVELOPMENT

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 configura tions, an attempt is made to identify the important processes involved . It is proposed that fog forms with an onshore wind when cold air dra inage from the plateau to the east creates a stagnation point in the n ear surface flow on the coastal plain. A full model integration with t ime-dependent boundary conditions supports this but shows an along-coa st variation associated with valleys that dissect the edge of the plat eau. It is concluded that in uneven terrain the development of local n octurnal winds may frequently determine the location and timing of fog formation.