Long-term observations of the oceans around Australia are providing the nation's climate scientists with significant benchmarks for seasonal forecasts and monitoring future climate change.Initiated near the end of a two-year El Nino event in May 1983, the program involves the deployment of simple "expendable instruments" (XBTs) from commercial shipping that measure temperature and currents to a depth of 800 metres along routes in the Indian, Pacific and Southern Oceans.
"There is so much ocean around Australia influencing our daily weather and longer term climate that it made sense to begin a record from which we could connect ocean change to shifts in rainfall patterns across southern Australia," said Dr Gary Meyers who, with colleagues at Commonwealth Scientific and Industrial Research Organisation (CSIRO), the Bureau of Meteorology (BoM) and the Scripps Institute of Oceanography in the US, established the ocean monitoring system.
"The 1982/83 El Nino came as a big surprise when we saw all kinds of changes around Australia but didn't understand them. Now these ocean temperature data contribute to the BoM's routine seasonal climate forecast."
At 25 years the system stands as one of the longest sustained ocean observing networks in the world, and is a rare long-term record of ocean change in the huge and poorly monitored Southern Hemisphere ocean domain.
Based on the records, CSIRO's Dr Susan Wijffels and co-authors at CSIRO's Wealth from Oceans National Research Flagship will publish a paper on the mean currents flowing between Australia and Indonesia in the Journal of Physical Oceanography. These currents form a critical ocean interconnection, the so-called Indonesian Throughflow, in the distribution of heat in the global climate system.
"Today, we have over 60,000 measurements of temperature around Australia that scientists regularly use to assess past long-term trends, test models used to predict future climate or forecast ocean behaviour," said Dr Meyers, who leads Australia's Integrated Marine Observing System (IMOS).
"More than 50 scientific publications and books have been published using the Australian data."
For their contribution, oceanographer Dr Gary Meyers acknowledged the support of Australian and international shipping companies, and their officers and crews, who make this program a vital contribution to climate science. Additional measurements come from research and Antarctic resupply vessels and the Royal Australian Navy.