Coupled Model Simulations Investigating the Role of East Australian Current Eddies in the Formation of East Coast Lows

Australian East Coast Lows (ECLs) are low pressure weather systems that can develop rapidly over the oceanic region where the warm East Australian Current flows southward. ECLs can produce intense hurricane scale winds and have historically been responsible for major flooding events, damage to coastal infrastructure, and the wrecking of multiple ships. ECLs are hybrid systems that can develop rapidly within large scale upper troughs and involve topographic influences and baroclinic processes, but within which deep convection also appears to play a critical role. Preliminary simulations using the Coupled Limited Area Model (CLAM) are used to investigate the role of the ocean in the formation of ECLs. In particular the role in storm development of SST gradients along the boundaries of warm and cold ocean eddies is considered. If deep convection is initiated along these boundaries in a cyclonically rotating environment then diabatic processes could redistribute potential vorticity and lead to intensification in a manner similar to that hypothesized to occur in tropical cyclones. The impact of ECLs on ocean conditions (e.g. SST, vertical mixing, and storm surge) is also investigated. This work forms part of an international research network from Canada, Australia, the U.K. and Brazil that aims to (a) improve short-term forecasts of extreme marine events, and (b) estimate the frequency of extreme marine events over coming decades with realistic measures of uncertainty.