How well do IPCC-AR4 models simulate Australian rainfall teleconnections during two-consecutive positive Indian Ocean dipole events?

It has been hypothesised that in a warmer world, positive Indian Ocean Dipole (pIOD) events, which refer to a phase with low sea surface temperature (SST) anomalies in the eastern Indian Ocean (IO) and warm anomalies in the west, may become more frequent or more intense, resulting in more drought-like conditions across much of Australia. Indeed, in 2006-2007 two consecutive pIOD events occurred in conjunction with a 2007 La Nina event causing wide-spread drought across eastern Australia. Significant improvements have been achieved in the simulation of Indo-Pacific variability, such as the IOD and the El Nino-Southern Oscillation (ENSO) by climate models used in the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4). In this paper, we discuss the dynamics behind Australian seasonal rainfall teleconnections associated with two-consecutive pIOD events and with one occurring in a La Nina year, using outputs from IPCC-AR4 climate models. The results show that only six out of 24 models produce at least one such combinations during the latter part of their 20th Century simulation, and that the associated evolution of rainfall anomalies are reasonably simulated.