Strengthening of Indian Ocean teleconnections permits predictions of springtime rainfall in SE Australia

Abstract

Rainy years and dry years in SE Australia are known to be correlated with sea surface temperatures in the specific areas of the Indian Ocean. While over the past 100 years the correlation had been both positive and negative, it significantly increased in strength since the beginning of the 21st century. Over this period, Indian Ocean sea surface temperatures during the winter months, together with the El Ni\~no variations, contain sufficient information to accurately hindcasts springtime rainfall in SE Australia. Using deep learning neural networks trained on the early 21st century data we performed both hindcasting and simulated forecasting of the recent spring rainfall in SE Australia, Victoria and South Australia. The method is particularly suitable for quantitative testing of the importance of different ocean regions in improving the predictability of rainfall modelling. The network hindcasting results with longer lead times are improved when current winter El Ni\~no temperatures in the input are replaced by forecast temperatures from the best dynamical models. High skill is limited to the rainfall forecasts for the September/October period constructed from the end of June.