Methods of assessing the performance of IPCC-AR4 models in simulating Australian rainfall teleconnections with Indo-Pacific climate drivers

Methods of assessing the performance of IPCC-AR4 models in simulating Australian rainfall teleconnections with Indo-Pacific climate drivers

Significant improvements have been achieved in the simulation of Indo-Pacific variability, such as the India Ocean Dipole (IOD) and the El Niño-Southern Oscillation (ENSO) by models used in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4). In this paper, we discuss Australian rainfall teleconnections with these modes using 20th Century experiments from 23 IPCC-AR4 climate models. The results show that averaged over all models, the Australian rainfall teleconnection with ENSO is too weak over eastern Australia, and too strong over the northwest Western Australia. The latter is due to the well-known bias associated with the Pacific cold tongue, which extends too far west. Both the ENSO and IOD rainfall teleconnections vary strongly from one model to another, although the rainfall teleconnection with the IOD is more realistic compared with observations. Factors such as the amplitude of the simulated ENSO, the structure of the model cold tongue, and the signal to noise ratio in determining the teleconnections will be discussed.