A new CSIRO led expedition to the Southern Ocean – aboard Research Vessel Investigator – remains on track despite a ‘precautionary’ return to port earlier this month due to crew member illness.
RV Investigator was forced home to Hobart only three days into a six week voyage to the Southern Ocean to return a crew member to shore for precautionary health treatment.
However, the minor setback has not delayed the progress of the mission which focuses in large part on the deployment of eleven new model, deep sea Argo robotic floats near the edge of the Antarctic.
The deployment of the next generation robots will add to the existing global network of more than 3,800 units; with the new models – capable of autonomous operation up to 5,000 metres deep – supplied by research organisations from the USA (Scripps), Japan (JAMSTEC) and France (LOCEAN).
“It’s the first time these next-generation deep water Argo floats will be deployed near Antarctica. By providing year-round measurements through the full ocean depth, the floats will fill a massive data gap for the climate research community,” Voyage Chief Scientist Dr Steve Rintoul said.
“The world’s climate is strongly influenced by the oceans, and the vast Southern Ocean plays a major role in how climate variability and change will play out in future decades,” Dr Rintoul said.
In addition to CSIRO, researchers from the Antarctic Climate and Ecosystems Cooperative Research Centre will also be making measurements of trace elements like iron, using ultra-clean techniques to avoid contamination.
An international team of scientists from agencies including CSIRO, the Australian Bureau of Meteorology, the US National Centre for Atmospheric Research (NCAR), and the University of Utah, will also conduct experiments exploring the interaction between aerosols and clouds.
Investigator is managed by the Marine National Facility and Australia’s only blue-water research vessel, enabling scientists from across the world to conduct research from the equator to Antarctica.
Going down south
“The weather so far has been kind to us, despite some fifty knot (90 plus kilomtere per hour) winds on one of the evenings,” Dr Rintoul reported recently, with the voyage so far traversing “a large eddy of warm and salty water from the East Australian Current, then entered the Subantarctic Zone where waters are cooler and fresher.
“The team are now near the Subantarctic Front, the strongest current jet in this part of the Southern Ocean, with strong flow to the east,” having moved in location from the south of Tasmania down to the 51st parallel south.
“Over 20 Conductivity, Temperature and Depth (CTD) instruments have been deployed (as well as) two regular Argo floats and one biogeochemical Argo float. The trace metal rosette has been deployed 12 times.
“Two in-situ pump stations – pumps that are lowered into the ocean and pump large volumes of water through a filter to measure low-concentration elements and isotopes – have been completed,” Dr Rintoul said.
On the horizon
“We are now slowly making our way up the mid-ocean ridge, so the water depth is slowly shoaling from depths of 4,500 to 2,500 metres.
“The team will be comparing these new measurements to previous occupations of this transect, a time series that started in 1991. In this way we will be able to track changes in the Southern Ocean,” Dr Rintoul said.
“The Southern Ocean takes up more of the extra carbon dioxide added to the atmosphere by human activities than any other region of the ocean; it also takes up most of the extra heat that has entered the ocean.
“More than 93% of the extra heat stored by the planet over the past 50 years is found in the ocean. This means the ocean provides the best thermometer we have to track how the earth’s climate is changing,” Dr Rintoul said.
Health and safety questions
Staff Association Secretary Sam Popovski said that the union would write to CSIRO following the completion of the expedition seeking clarification on safety standards for members, crew, CSIRO employees, international collaborators and other passengers during future expeditions.
“It’s good news that the medical situation has been handled without delay to the scientific mission, however the safety of those onboard Investigator is always paramount.
“Following the safe return of the research vessel, the Staff Association will write to CSIRO for clarification of the corporate health, safety and environment (HSE) standards for Investigator including medical facilities and emergency protocols,” Mr Popovski said.