A skill score based evaluation of simulated Australian climate

Abstract

The three Australian submissions to CMIP5, based on two versions of the ACCESS coupled climate model and the upgraded CSIRO model Mk3.6, are evaluated using skill scores for both global fields and for features of Australian climate. Global means of surface air temperature and precipitation are similar to those from observational datasets, except for a cool bias in Mk3.6. The agreement of the climatological seasonal mean fields for these and eleven other quantities, as measured by the M score, is comparable to the Australian CMIP3 models, in the case of Mk3.6, but mostly improved on by both ACCESS1.0 and ACCESS1.3. The ACCESS mean sea-level pressure and winds are notably better. An overall skill score, calculated for both global and Australian land, shows that the ACCESS models are among the best performing of 25 CMIP5 models. ACCESS1.0 improves slightly on the U.K. Met Office submissions. A suite of tests developed for the CAPTIVATE project is applied, and again ACCESS1.0 matches the U.K. Met Office reference model. ACCESS1.3 has improved cloud cover and a better link between equatorial sea surface temperatures (SSTs), using the Pacific-Indian Dipole index, and Australian rainfall. Mk3.6 has excessive variability in the SST index. In all, both versions of ACCESS are highly successful, while the ensembles of simulations of Mk3.6 make it also a very worthwhile submission to CMIP5.