CFCs were first produced for use as refrigerants in the 1930s. Scientists use CFC tracers to calculate how recently a water mass was at the surface, providing a 'clock' with which to measure the motion of water masses. Understanding the role of ocean circulation in controlling the biological productivity of Southern Ocean surface waters . The Southern Ocean is not as productive as expected, given the abundant nutrients. A variety of biological and chemical measurements are made during expeditions on the Aurora Australis and the Southern Surveyor to investigate the factors controlling the biological productivity of the Southern Ocean.
Ships provide an opportunity to make observations over a wide area at a particular time.
To obtain measurements at particular sites over a long period, moorings are used. Australian and US scientists have recently deployed the most comprehensive array of moorings ever deployed in the Southern Ocean along the repeat transect between Tasmania and Antarctica. To answer these questions, three types of instruments are being used. Conventional current meters , which use a rotor and a vane to measure current speed and direction, have been deployed in the centre of the array. The other instruments are being used for the first time in the Southern Ocean.