Recent progress towards understanding cold fronts in the Australian region is re-viewed, with emphasis on the summertime 'cool change' of southeastern Australia. We discuss a conceptual model for the cool change, based on observational data obtained during the Australian Cold Fronts Research Programme (1979-1987), and relate this to theoretical ideas that have emerged from numerical model studies. The importance of synoptic-scale frontogenetic forcing, and the role of strong diabatic heating on frontal behaviour are stressed. Orographic influences and the development of the 'southerly buster' along the east coast of New South Wales are discussed in the light of field measurements and recent modelling studies. The presence of a pre-frontal surface-based stable layer can lead to the generation of a bore-like disturbance which moves ahead of the air mass change. The passage of the bore brings about a sharp rise in pressure, a strong, but in some cases temporary wind surge, and frequently an abrupt rise in temperature. The latter is caused by the downward mixing of potentially warm air by turbulence at the bore. Such disturbances appear to be common a few hours before sunrise over the continent, but renewed diabatic heating during the day removes the stable layer and the bore decays. Accordingly, cold fronts over the continent show a marked diurnal variation in structure. Over the sea, bore-like disturbances are likely to be most pronounced during the daytime when there is a hot offshore pre-frontal wind. Recognition of this type of behaviour is important for a correct analysis of fronts.
Reeder et al. (Sun,) studied this question.