Argo floats have revolutionised our understanding of the broad scale structure of the oceans to 2000 m depth. In the past 10 years more high resolution hydrographic profiles have been provided by Argo floats then from the rest of the observing system put together.
Argo floats alter their buoyancy by using a battery pack and motor to drive oil from inside the float to an external bladder. This changes the floats volume and thus its density relative to the surrounding seawater allowing it to move up and down through the water column. The diagram below shows the inner workings of an Argo float with the major component parts labelled.
Argo floats also send us engineering data to help track the performance of the hardware and diagnose errors. Our realtime engineering data with plots can be seen at the CSIRO Argo technical website.