Sea sentinels placed on climate watch
Sea patrol Marine sensors have been deployed to the north of Australia to measure changes in ocean currents moving between the Pacific and Indian oceans.
CSIRO scientists hope the long-term monitoring program will increase the accuracy of ocean circulation and climate models, and improve climate assessment outcomes for Australia and the region.
Three moorings were laid last month, with two placed in the Timor Passage and one in the Ombai Strait, north of East Timor.
The moorings, worth more than $1 million, join other monitoring moorings off the Kimberley Shelf in north-western Australia and the continental shelf off Darwin.
Dr Bernadette Sloyan, of CSIRO's Wealth from Ocean Flagship and the Centre for Australian Weather and Climate Research says the array of moorings will improve knowledge of coastal conditions around Australia, the Leeuwin Current along the west coast of Australia, and the Indonesian Throughflow.
The Indonesian Throughflow is a powerful system of ocean currents that moves water, and transfers heat, from the equatorial waters of the Pacific Ocean to the Indian Ocean.
The Timor Passage and Ombai Strait account for 80 per cent of the transfer of water from the Pacific to Indian oceans and act as "chokepoints" in the global system of ocean currents.
Sloyan says the throughflow influences seasonal climate in Australia, but also plays a major role in global climate.
Long-term records needed
It is also an important pathway for the transfer of climate signals around the globe.
Through the marine sensors researchers will be able to track variations in the movement of water, salinity and temperature.
"While the heat and fresh water carried by the Throughflow are known to affect the characteristics of both the pacific and Indian Oceans, variations from year to year and from decade to decade concerning the size, depth and distribution of the flow remains a troublesome unknown," says Sloyan.
"We have a three-year record but that doesn't even cover an El Niŉo or ENSO cycle," she says. ENSO is the oscillation between the El Niŉo and La Niŉa weather patterns.
"Long-term climate impacts need long-term records."
Sloyan says the top-half of the moorings is made of strengthened wire while the lower end is synthetic rope.
Modelling was used to determine the length of the mooring, with breaks in the line for marine sensor instruments and buoyancy.
She says it took five hours to lay the moorings out behind the boat and then a four-tonne anchor was dropped at the planned site to hold the mooring in place.
The moorings sit 40 metres below the sea surface to ensure they do not disturb shipping routes.
It is hoped they will provide data for at least 10 years, but the first information from the sensors will not be retrieved for 18 months.