Sea Level and Rainfall Correlations in Australia: Tropical Links

Abstract

A preliminary study is made of simultaneous and lagged seasonal cross correlations between northern Australian sea level and district rainfall anomalies. Zero-lagged patterns show strong links with the El Niño/Southern Oscillation (ENSO) phenomenon over northern and eastern Australia during austral winter–spring seasons. These findings are similar to, but more robust than, those reported for simultaneous cross correlations between Australian district rainfall and either the southern oscillation index, Darwin mean sea level pressure, or northern Australian sea surface temperatures. This appears to be a consequence of the strong integrating response of northern Australian sea levels, particularly to inverse barometric and wind forcings on seasonal time scales. Such relationships are explored further in lagged cross correlations. As observed in other studies of seasonal persistence associated with ENSO and anti-ENSO phases, rainfall precursors extend in time from one to two seasons. However, significant seasonal cross correlations are found at longer intervals, reflecting the marked sea level response to the often observed anti-ENSO to ENSO sequence of the phenomenon. In particular, austral spring sea levels in northern Australia are negatively correlated with the following austral winter rainfall over parts of northern and south-southeastern Australia. At present an operational evaluation of precursors must await the installation of new telemetering tide gauges in northern Australian ports.