The role of Atlantic variability in modulating the tropical cyclone formation in the Australian region

Previously the interannual variability of tropical cyclone genesis (TCG) in the Australian region has mainly been attributed to the climate variability in the Pacific and Indian Oceans. In this study, we found that the influence from climate variability in the Atlantic is of equal importance. Application of a state-of-the-art causality analysis reveals that the Atlantic meridional mode (AMM), Atlantic multidecadal oscillation (AMO) and north tropical Atlantic (NTA) sea surface temperature (SST) anomalies are all causal to the Australian region TCG frequency. The associated physical mechanisms are investigated as well. Based on this causal analysis and inference, a statistical model is constructed to forecast TCG, using the Poisson regression and the step-by-step predictor selection method. The Atlantic causal factors, after being taken in as new predictors, help increase the forecast skill for the seasonal Australian region TCG by as much as 10% in terms of correlation increase and 40% in terms of root-mean-square error reduction.