Antarctica is located in what is commonly called the Southern Ocean, one of the richest marine ecosystems in the world. Three basic water masses comprise the Southern Ocean: Antarctic Surface Water, Circumpolar Deep Water, and Antarctic Bottom Water. The boundaries between the water masses tend to be sharp. On the continental shelf of Antarctica, there are two main water masses: Surface Shelf Water and a modified version of Circumpolar Deep Water.
Each water mass has different characteristics, and these differences drive circulation around the continent. As part of the global heat engine, the Antarctic has a major role in the world’s transfer of energy. Its ocean/atmosphere system is known to be both an indicator and a component of climate change. Oceanographers are attempting to improve our understanding of this oceanic environment, including global exchange of heat, salt, water, and trace elements, sea-ice dynamics, and marine biosphereresearch.
One of the most important ocean processes-one that is uniquely related to the Antarctic-is ocean ventilation, the process by which the deep ocean affects the atmosphere on the time scale of decades to centuries. If we could mark a cubic meter of sea water and follow its global meanderings through the various oceanic current systems, we would find that it spends most of its time isolated in the deep ocean, where it is dark and cold. Only occasionally-once every 600 years on the average-would it appear on the surface, and then only south of the Antarctic Circumpolar Current. This process is called overturning or ventilation of the ocean. Typically, when deep water reaches the surface, it gives up heat to the much colder atmosphere and picks up dissolved atmospheric gases, including carbon dioxide. The ventilation or overturning of the ocean can significantly affect climate change.