Ocean acoustic tomography water formation and the gyre circulation. Other applications include the measurement of ocean tides, and the estimation of ocean mesoscale dynamics by combining tomography, satellite altimetry, and in situ data with ocean dynamical models. In addition to the decade-long measurements obtained in the North Pacific, acoustic thermometry has been employed to measure temperature changes of the upper layers of the Arctic Ocean basins, which continues to be an area of active interest. using data from acoustic pulses sent from one end of the earth to the other. Acoustic thermometry is an idea to observe the world's ocean basins, and the
Southern Ocean four toothed whales. The largest of these, the blue whale ("Balaenoptera musculus"), grows to long weighing 84 tonnes. Many of these species are migratory, and travel to tropical waters during the Antarctic winter. Five species of krill, small free-swimming crustaceans, have been found in the Southern Ocean. The Antarctic krill ("Euphausia superba") is one of the most abundant animal species on earth, with a biomass of around 500 million tonnes. Each individual is long and weighs over . The swarms that form can stretch for kilometres, with up to 30,000 individuals per , turning the water red. Swarms usually remain