A two-layer, quasi-geostrophic model incorporating orography, surface healing and the release of latent heat in convection is used to study the semi-permanent trough/ridge system of northeastern Australia. The model produces realistic flow patterns and these are used to examine the way In which various parameters affect the flow. It is found that the factors which are most favourable for a large-amplitude trough/ridge system art: (a) a shallow easterly low-level airstream, and (b) weak vertical wind shear. Results obtained suggest that there may be a positive feedback between latent heal released and the inland trough acting in such a way that the trough triggers the release of latent heat which, in turn, assists in maintaining the trough.
M. Adams (Mon,) studied this question.