Navy Ship launches profilers to help climatologists predict deep ocean currents
14 September 2007
Royal Australian Navy (RAN) ship HMAS Adelaide (II) may be on its swan-song voyage before its decommissioning next year but the ship's company is taking part in a futuristic project to help scientists predict the influence of climate change on deep ocean currents.
The Royal Australian Navy is working with the CSIRO's Division of Marine and Atmospheric Research in Hobart to measure deep ocean temperatures and currents through the deployment of robotic ocean profilers that are part of the Argo ocean monitoring program.
Argo is an international collaboration of 26 countries that collects temperature and salinity profiles from the upper 2000 metres of the ice-free global ocean. Some profiling floats also measure oxygen, turbidity and deep ocean currents.
The $25,000 floats or profilers have a life of around four years. They drift with the currents and cycle between a depth of 2,000 metres and the surface every 10 days, uploading their temperature and salinity data to satellite while on the surface. They are a central feature of Australia's new Integrated Marine Observing System, bringing together existing and new components of a network to observe coastal waters and the deep ocean.
HMAS Adelaide, the oldest of the RAN's long range guided missile frigates, has provided an important platform for the launch of the Argo floats since Australia joined the initiative in 2006.
During its final voyage to India and South East Asia for Exercise MALABAR, Adelaide launched a set of floats North West of Christmas Island, bringing to 11 the total of floats deployed from the ship.
Data from the floats deployed by Adelaide are combined with information from almost 3000 floats which are currently active world-wide, giving climate researcher's unprecedented access to ocean temperature and salinity profiles from areas which are otherwise inaccessible. Argo data underpins all current research into climate change and variability and provides critical input to the joint RAN/Bureau of Meteorology and CSIRO project BlueLINK, designed to deliver ocean forecasts (similar to weather forecasts) to the Australian maritime community.
The Commanding Officer of Adelaide, CMDR Rob Slaven, said that it was pleasing that Adelaide was able to contribute to the Argo program during its final voyage prior its decommissioning on 19 January 2008.
" Adelaide is proud to be part of this international collaboration to map the world's oceans," CMDR Slaven said.
"The data gleaned from the Argo array will not only enhance the Navy's own capability to operate effectively in changing maritime and climatic conditions but will also enable future generations develop the tools to better manage the deep ocean environment," CMDR Slaven said.
Background
- Drawing on Greek mythology, Argo is named after the ship in which Jason sailed in search of the Golden Fleece and emphasizes the strong relationship between the global float array with the Jason satellite altimeter system.
- The Argo float is a direct descendant of Dr John Swallow's (1923-1994) invention of the neutrally buoyant float that made the first deep current measurements in 1955.
- Argo has been the largest single source of ocean profile data since 2002 and marks the first step towards the development of a co-ordinated and comprehensive long term global observation system.
- The Argo array extends beyond the 750m limit of previous observation systems and is able to measure temperature more accurately as well as collecting salinity and ocean current data.
- These earlier observations had other limitations. Temperature probes were usually dropped from individual merchant ships or research vessels but these probes only provided short term data, were mostly confined to the main commercial shipping routes and were seasonally dependent.
- Argo draws on the combined maritime resources of 27 nations and has a broader reach than previous attempts with an array extending into the ice-free regions of the Southern Ocean and the North Atlantic.
- Floats can be deployed from a range of platforms, from small research boats up to huge container vessels and even aircraft and warships.
- The Argo array is expected to reach 3000 by the end of 2007 and be sustained at this level well into the future provided contributing nations continued deploying around 800 floats per year.
- This annual deployment of 800 floats will effectively populate the world's ice-free oceans at a density of one float every 3x3 degrees or 300 kms.
- The total annual cost of Argo is about $A20m or approx. $25,000 per float lifetime which means that each profile costs around $200.
