Argo achieves its 3000 float target

Over 3000 active Argo floats
Over 3000 active Argo floats ©

07 November 2007

The oceans cover 70% of the Earth's surface and are a major influence on our climate system, yet relatively little is known about them.

Argo, a worldwide programme involving over 30 countries, was established in 2000 to provide regular measurements from previously data-sparse areas throughout the ice-free deep-ocean areas to improve our understanding.

Its aim was to create a global network of over 3000 active profiling floats. These specialised floats are able to descend and ascend through the water column by changing their buoyancy.

During October 2007, over 100 floats were deployed by various Argo scientists around the world to reach this target. It is expected that 800 new floats will need to be launched each year to maintain the 3000 float array, as a float can only operate for approximately four years.

Argo data

Each float sinks to a depth between 500 and 2000 metres, and drifts for five or nine days — providing information about ocean circulation. It then descends, if necessary, to a depth of 2000 metres to start data collection. As the float rises to the sea surface it collects temperature, salinity and pressure measurements. At the surface it transmits the data collected via satellite to a receiving station, before repeating the cycle.

The data are vital for monitoring ocean temperature, a key factor in climate change, and are also used by the Met Office in their ocean-atmosphere computer models to define the initial ocean conditions and circulation, thus providing more accurate seasonal forecasts.

UK Argo

The UK Argo programme has deployed around 230 floats to date. One of which, signed by comedian Marcus Brigstocke, was deployed during the Cape Farewell Greenland voyage. Cape Farewell is a charitable organisation which brings together artists, scientists and educators to collectively address and raise awareness about climate change.

Another prestigious UK float deployment is planned for late November 2007, in the western Indian Ocean. The BBC will deploy a float during the filming for OCEANS, an eight part television series about the sciences and history of our seas and oceans.

The UK Argo programme is managed by the Met Office in partnership with the

  • National Oceanography Centre, Southampton (NOCS)
  • UK Hydrographic Office (UKHO)
  • British Oceanographic Data Centre (BODC)

and is jointly funded by the Department for Environment, Food and Rural Affairs (defra), the Ministry of Defence (MOD) and the Natural Environment Research Council (NERC).

BODC act as the data centre for UK floats in the Argo programme, regardless of their location. We also act as the Regional Data Centre for the Southern Ocean in collaboration with the Commonwealth Scientific & Industrial Research Organisation (CSIRO), Australia.