Southern Oscillation Index and transmission of the Barmah Forest virus infection in Queensland, Australia

El Nino-Southern Oscillation (ENSO) events are usually accompanied by changes in the trade winds, cloud amounts and rainfall over the tropical Pacific and Australian regions,and seem to be related to many climatic anomalies around the globe. A measure of ENSO is the Southern Oscillation Index (SOI),which is the normalised atmospheric pressure diVerence between Tahiti in the south Pacific and Darwin in northern Australia. The SOI is closely related to variations in temperature and rainfall across the Pacific and in eastern Australia. 1