Moorings back in the Roaring Forties

Two Southern Ocean moorings that take measurements aimed at improving scientists’ understanding of how the ocean processes carbon were successfully redeployed in August. ACE Carbon program leader Professor Tom Trull led the voyage from Hobart on the Southern Surveyor and, despite some “unpleasantly lumpy” seas, described it as very successful. Deployment and retrieval of moorings in the Southern Ocean is a complex undertaking. The two moorings – called Pulse-8 and SAZ47-14 - are located 580 km southwest of Tasmania. They are part of the Southern Ocean Time Series facility, which is a facility in Australia’s Integrated Marine Observing System, and also part of the OceanSITES international network of open ocean observatories. The Pulse-8 mooring has sensors which provide biogeochemical information on the ocean including temperature, salinity, dissolved oxygen, total dissolved gases, phytoplankton fluorescence, particulate optical backscatter, photosynthetically available radiation and dissolved nitrate concentrations.  It will also collect water samples at approximately weekly intervals for later measurement of dissolved nitrate, silicate, inorganic carbon, alkalinity and phytoplankton identification. The SAZ47-14 mooring has funnel-shaped sediment traps which collect samples that will tell scientists how much particulate carbon and other materials are being taken into ocean’s interior. Samples are taken at depths of 1000m, 2000m and 3500m. With the exception of some wave data, transmitted via satellite, the information gathered by both moorings will be analysed by scientists when the moorings are recovered in winter 2012. The instruments at the Southern Ocean Time Series facility are recording processes that vary on daily, weekly, seasonal and yearly timescales, which means that obtaining observations with the necessary frequency is not possible from ships. This is the third outing for the Pulse mooring. The SAZ47 mooring has been deployed approximately annually since 1997. An ocean glider deployed on the voyage will obtain spatially distributed measurements of temperature, salinity, oxygen, phytoplankton fluorescence and particle backscatter in the vicinity of the moorings, as it steers itself slowly back to Tasmania. A third mooring at the facility – the Southern Ocean Flux System, which measures meteorological and oceanographic conditions - was retrieved in April and will be redeployed in November.


Authorised by the CEO of the Antarctic Climate and Ecosystems Cooperative Research Centre October 2019.

The ACE CRC was established and supported under the Australian Government’s Cooperative Research Centres Program.

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