Mean sea level pressure indices of the El Nino-Southern Oscillation: relevance to stream discharge in south-eastern Australia

Six separate Southern Oscillation Index (SOI) series are discussed here, all based entirely or in part on observations of mean sea level pressure at Tahiti and Darwin. Three of the six appear to offer promise in future water-resource assessments in regions of Australia subject to ENSO influence. Over the century of river discharge records beginning in 1891, annual natural inflows to Hume Reservoir, located on the inland slopes of the Great Dividing Range of south-eastern Australia, show appreciable correlation with SOI values. Annual natural inflows to Hume Reservoir average almost a factor of two greater during strong La Nine, compared to strong El Nino episodes.