Numerous regional climate simulations have been completed for the Australian region by nesting the Division of Atmospheric Research Limited-Area Model (DARLAM) within the R21, 9-level CSIRO GCM and within ECMWF analyses. The climatologies generated from these runs have consistently shown improvements over Australia corresponding to the increased horizontal resolution. In this study, the characteristics of the storm tracks are examined for the latest runs, nested within transient and equilibrium GCM simulations and also within analyses.
The ability of the model to capture the location and magnitude of the storm tracks, and their interannual variation, will be presented. The effectiveness of the forcing provided by the lateral boundary conditions upon the climate over Australia is assessed by comparing the simulations nested within analyses to those nested within the GCM. In addition to investigation of the mean storm track and its relation to the surface climate, aspects of the daily and interannual variability of the model are also examined.
The mean baroclinic structure of the various simulations are analyzed using regression/correlation analyses to determine whether these structures are realistic, and how these structures are likely to change under doubled-greenhouse gas conditions.
A key result is that there is a decrease in intensity of the low level storm track due to a decrease in low level baroclinicity, whilst the converse is true for upper levels. Complementary changes in the baroclinic structure are also noted.