Modelling a coastal ridging event over south-eastern Australia

Abstract

Coastal ridging is an important component of the weather of south-eastern Australia during the summer. The mesoscale aspects of such an event are often not well forecast, and this can have serious implications for aviation, shipping, air quality and bushfire control. A previous study by Speer & Leslie (1997) identified three types of coastal ridging according to the associated synoptic conditions. In this study, a coastal ridging event, which appears to have aspects of all three types, is examined with the aid of mesoscale manual analyses, surface and radiosonde data and simulations with a mesoscale numerical model (Colorado State University Regional Atmospheric Modeling System).

It is found that the model is able to capture the salient features of the event but, on the east coast, tends to produce a weaker event than that observed. The model ridging also tends to lag the observed feature on the east coast by a few hours. It is suggested that these model deficiencies may relate to deficiencies in the lower atmosphere air mass characteristics, which, in turn, may relate to the surface parameterisations in the model.