A physics ensemble investigation of the 8th July 2007 Newcastle storm.

The severe East Coast Low event at Newcastle, Australia on the 8th of July 2007 caused widespread flooding and damage including the beaching of the Pasha Bulker. In this study this event is simulated using the Weather Research and Forecasting (WRF) model. By varying the physical parametrizations for the planetary boundary layer, the surface layer, the cumulus convection, microphysics and the radiation a 36 member physics ensemble was produced. By evaluating the simulations against various observational datasets the “best” collection of physics parametrizations is identified along with an estimate of the uncertainty associated with imperfect parametrizations. By carefully selecting two physics parametrization collections that reside near the outer edges of the 36 member ensemble we are able to identify a three member ensemble (the “best” plus the two outer) that spans almost all the variability found within the 36 member ensemble and which can be applied to a longer time series with minimum computational cost.