How long do phases of the Interdecadal Pacific Oscillation (IPO) persist?: utilising palaeoclimate data in stochastic hydrology

Incorporating the influence of climate change and natural variability into stochastic hydrology is a priority for water resource planners who are being challenged by changing supply and demand patterns. The influence of large scale ocean-atmosphere climate mechanisms on Australia’s highly variable rainfall regimes is a valuable means for improving the ability of stochastic models to characterise hydrological variability. This paper re-evaluates the characterisation of Pacific Ocean hydro-climatological variability using multiple independent palaeoclimate records for the Interdecadal Pacific Oscillation (IPO) and the Pacific Decadal Oscillation (PDO). A suitable stochastic model for the persistence of phases of the IPO/PDO is developed. The simulations were incorporated into a seasonal stochastic rainfall model and applied to three sites on the East coast of Australia. The analysis in this paper provides an improved understanding of the decadal-scale variability of Pacific Ocean climate processes over the past 500 years. The findings could have considerable implications for water resource planners seeking to incorporate the influence of the large scale ocean-atmosphere climate mechanisms into water resource planning