CSIRO PUBLISHING Journal of Southern Hemisphere Earth Systems Science, 2019, 69, 205–215 https://doi.org/10.1071/ES19015 Analysis of a southerly buster event and associated solitary waves Shuang WangA,B,D, Lance LeslieA, Tapan RaiA, Milton SpeerA and Yuriy KuleshovC AUniversity of Technology Sydney, Sydney, NSW, Australia. BBureau of Meteorology, PO Box 413, Darlinghurst, NSW 1300, Australia. CBureau of Meteorology, Melbourne, Vic., Australia. DCorresponding author. Email:
[email protected] Abstract. This paper is a detailed case study of the southerly buster of 6–7 October 2015, along the New South Wales coast. It takes advantage of recently available Himawari-8 high temporal- and spatial-resolution satellite data, and other observational data. The data analyses support the widespread view that the southerly buster is a density current, coastally trapped by the Great Dividing Range. In addition, it appeared that solitary waves developed in this event because the prefrontal boundary layer was shallow and stable. A simplified density current model produced speeds matching well with observational southerly buster data, at both Nowra and Sydney airports. Extending the density current theory, to include inertia-gravity effects, suggested that the solitary waves travel at a speed of ,20% faster than the density current. This speed difference was consistent with the high-resolution satellite data, which shows the solitary waves moving increasingly ahead of the leading edge of the density current. Additional keywords: coastally trapped disturbance, density currents. Received 19 May 2019, accepted 7 October 2019, published online 11 June 2020 1 Introduction speed of ,20 m/s at the leading edge of the ridge (Holland and Southerly busters (SBs) occur during the spring and summer Leslie 1986).