The Southern Ocean has a predominant role in the movement of heat and carbon dioxide into the ocean interior, moderating Earth’s average surface climate. The IMOS Southern Ocean Time Series (SOTS) ocean monitoring equipment consists of a set of automated moorings to measure these processes under extreme conditions, where they are most intense and have been least studied.
The atmosphere-ocean exchanges occur on many timescales, from daily cycles to ocean basin decadal changes. IMOS is collecting high frequency observations sustained over many years to enable a better understanding of these processes.
Dr Tom Trull from CSIRO and the Antarctic Climate & Ecosystems Cooperative Research Centre (ACE CRC) is the leader of the IMOS SOTS Observations sub-facility. Dr Trull is Co-Chief Scientist on this voyage with Dr Eric Schulz from the Bureau of Meteorology, who leads the IMOS Air-Sea Flux Stations sub-facility.
The primary objective of the scientific voyage is to first deploy a new set of SOTS moorings and then recover the existing SOTS moorings. Additional work will obtain information on atmospheric and oceanographic conditions using submersible instruments, including CTD casts, the Triaxus towed body, and shipboard sensors.
This voyage will also support projects that aim to advance understanding of aspects of biological processes that contribute to the control of carbon dioxide uptake. One control is the availability of dissolved iron, which is the limiting nutrient for phytoplankton productivity, despite being present at lower than parts per billion levels.
To determine this availability, a new trace-element clean water sampler designed to collect monthly samples for iron analyses will be trialled inside one of the floats. This device is a contribution to the project from the ACE CRC. Studies of sinking particles will also be carried out to examine the processes that strip iron from surface waters and carry organic carbon to the ocean interior.
Another new effort will be the deployment of an acoustic-optical profiler to provide information on the diversity, distribution, biomass of small crustaceans, squids, fishes and gelatinous organisms that are a key biological link between primary production by the phytoplankton and larger fish and top predators.
“The current context of anthropogenic forcing of rapid climate change adds urgency to the work,” said Dr Trull.
“The effort required to understand our changing ocean requires global effort, and we are particularly pleased to be joined this year by several international teams working to ensure data comparability among national effort,” he said.
Watch our 'IMOS in MOcean' video that explains the role of the Southern Ocean in climate processes and how IMOS contributes to our knowledge of these processes.
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