The Antarctic Intermediate Water is formed in the Southern Ocean and is characterized by a salinity minimum below the thermocline. It is found north of the Subantarctic Front. This water mass plays an important role in the South Atlantic and in the global ocean circulation since it contributes significantly to the northward flow of the upper limb of the Meridional Overturning Circulation.
There are two source water masses that feed into the Antarctic Intermediate Water found in the Atlantic Ocean. One of them is the Subantarctic Mode Water, which is formed in the Pacific Ocean and enters the southwest Atlantic through the Drake Passage. This water mass is found south of the Subantarctic Front. The second one is Antarctic Intermediate Water of Indian Ocean origin that flows into the eastern South Atlantic via the Agulhas/Benguela Current system.