Dr Ian Watterson1, Lauren Stevens1, Mark Collier1, Terry O’Kane2
1CSIRO, Aspendale, Australia,
2CSIRO, Hobart, Australia
CSIRO’s new Decadal Forecasting Project aims to investigate climate predictability and deliver multi-year climate forecasts for Australia. A prototype Climate Analysis and Forecast Ensemble System has been based on the ACCESS Ocean – GFDL AM2.1 coupled model. Given the potential importance of ENSO and the southern annular mode (SAM) to the variability of Australian rainfall, the links between these are explored first in a 100-year climatological simulation. Regression fields show that anomalies in atmospheric circulation linked to both the NINO34 ENSO index and a height-based SAM index extend through much of the southern hemisphere. Correlations between NINO34 and rainfall in eastern and northern Australia exceed –0.5 in summer and spring, in part through a link between NINO34 and SAM. These links can be seen also in two versions of ensemble forecast simulations, initialised from 1 January in years 2004-2016. Variability is enhanced for a year or more in the version that includes assimilation of observed ocean temperatures in the initial states and the use of mode-like perturbations. Given the links, predictive skill in forecasting NINO34 would imply some predictability in anomalies of SAM and Australian rainfall.
Dr Ian Watterson is a senior principal research scientist at CSIRO Oceans and Atmosphere, located at Aspendale where he has worked since 1989. From a background in atmospheric dynamics, he has contributed to CSIRO climate modelling and climate impact programs over the years. He was one of the lead authors of the recent Australian projections, and also of the IPCC’s Climate Change 2007, and has written over 60 journal papers. Dr Watterson is currently contributing to CSIRO’s new Decadal Forecasting Project, along with co-authors of the submission to C3DIS.