Editing Antarctic Circumpolar Current (section)

== Structure ==
[[Image:Antarctic Circumpolar Current.jpg|thumb|The Antarctic Circumpolar Current is the strongest current system in the world oceans and the only ocean current linking all major oceans: the Atlantic, Indian, and Pacific Oceans.  Seawater density fronts after {{Harvnb|Orsi|Whitworth|Nowlin|1995}}.]]
The ACC connects the [[Atlantic Ocean|Atlantic]], [[Pacific Ocean|Pacific]], and Indian Oceans, and serves as a principal pathway of exchange among them. The current is strongly constrained by [[landform]] and [[bathymetric]] features. To trace it starting arbitrarily at South America, it flows through the [[Drake Passage]] between South America and the [[Antarctic Peninsula]] and then is split by the [[Scotia Arc]] to the east, with a shallow warm branch flowing to the north in the [[Falkland Current]] and a deeper branch passing through the Arc more to the east before also turning to the north. Passing through the Indian Ocean, the current first retroflects the [[Agulhas Current]] to form the [[Agulhas Return Current]] before it is split by the [[Kerguelen Plateau]], and then moving northward again. Deflection is also seen as it passes over the [[mid-ocean ridge]] in the Southeast Pacific.

===Fronts===
The current is accompanied by three [[Front (Oceanography)|fronts]]: the Subantarctic front (SAF), the [[Polar front]] (PF), and the Southern ACC front (SACC).<ref>{{Harvnb|Stewart|2007}}</ref> Furthermore, the waters of the Southern Ocean are separated from the warmer and saltier subtropical waters by the [[subtropical front]] (STF).<ref>{{Harvnb|Orsi|Whitworth|Nowlin|1995|loc=Introduction, p. 641}}</ref>

The northern boundary of the ACC is defined by the northern edge of the SAF, this being the most northerly water to pass through Drake Passage and therefore be circumpolar. Much of the ACC transport is carried in this front, which is defined as the latitude at which a subsurface salinity minimum or a thick layer of unstratified Subantarctic [[mode water]] first appears, allowed by temperature dominating density stratification. Still further south lies the PF, which is marked by a transition to very cold, relatively fresh, Antarctic Surface Water at the surface. Here a temperature minimum is allowed by salinity dominating density stratification, due to the lower temperatures. Farther south still is the SACC, which is determined as the southernmost extent of [[Circumpolar deep water]] (temperature of about 2&nbsp;°C at 400&nbsp;m). This water mass flows along the shelfbreak of the western Antarctic Peninsula and thus marks the most southerly water flowing through Drake Passage and therefore circumpolar. The bulk of the transport is carried in the middle two fronts.

The total transport of the ACC at Drake Passage is estimated to be around 135&nbsp;Sv, or about 135 times the transport of all the world's rivers combined. There is a relatively small addition of flow in the Indian Ocean, with the transport south of [[Tasmania]] reaching around 147&nbsp;Sv, at which point the current is probably the largest on the planet.