The sea-ice performance of the Australian climate models participating in the CMIP5

The sea-ice performance of the Australian climate models participating in the CMIP5 experiment, ACCESS1.0, ACCESS1.3 and CSIRO-Mk3.6, is assessed. Comparison with model output from five other international climate modelling centres and observational data are also included in the assessment process. The assessment takes into account modelled climatologies and interannual variability of the sea ice extent, concentration, thickness and transport. The ACCESS models give good simulations of the global sea-ice, within the scatter of models studied, and is one of the top performing models for sea-ice metrics. CSIRO-Mk3.6 has too extensive sea-ice and the sea-ice model would likely have performed significantly better after adjustment of the model parameters. As a consequence, ACCESS and CSIRO-Mk3.6 show opposite hemispheric climate sensitivities in terms of sea ice. The ACCESS models generally capture the observed decline of the Arctic sea ice over the period of 1981–2011, but not the small increase in the Antarctic sea ice, although the simulated changes over this period are generally smaller in the Antarctic than in the Arctic. In the Arctic, the sea-ice reductions in the ACCESS models occur in the Laptev and Kara Seas rather than in the Chukchi and Beaufort Seas as observed.