Western boundary current

The North Atlantic Current (NAC), also known as North Atlantic Drift and North Atlantic Sea Movement, is a powerful warm western boundary current within the Atlantic Ocean that extends the Gulf Stream northeastward.

The Kuroshio Current (黒潮; "Black Tide"), also known as the Black Current or Japan Current (日本海流, Nihon Kairyū), is a north-flowing, warm ocean current on the west side of the North Pacific Ocean basin. It was named for the deep blue appearance of its waters. Similar to the Gulf Stream in the North Atlantic, the Kuroshio is a powerful western boundary current that transports warm equatorial water poleward and forms the western limb of the North Pacific Subtropical Gyre. Off the East Coast of Japan, it merges with the Oyashio Current to form the North Pacific Current.

The Kuroshio Current has significant effects on both physical and biological processes of the North Pacific Ocean, including nutrient and sediment transport, major pacific storm tracks and regional climate, and Pacific mode water formation. Additionally, the current's significant nutrient transport results in a biologically rich ecoregion supporting an important fishing industry as well as diverse marine food webs. The South China Sea for example has relatively low nutrient concentrations in its upper waters, but experiences enhanced biological productivity due to the input from the Kuroshio Current Intrusion. Ongoing research centered around the Kuroshio Current's response to climate change predicts a strengthening in surface flows of this western boundary current which contrasts the predicted changes in the Atlantic Ocean's Gulf Stream.

The Agulhas Current (/əˈɡʌləs/) is the western boundary current of the southwest Indian Ocean. It flows south along the east coast of Africa from 27°S to 40°S. It is narrow, swift and strong. It is suggested that it is the largest western boundary current in the world ocean, with an estimated net transport of 70 sverdrups (70 million cubic metres per second), as western boundary currents at comparable latitudes transport less — Brazil Current (16.2 Sv), Gulf Stream (34 Sv), Kuroshio (42 Sv).

The East Madagascar Current is an oceanic flow feature near Madagascar. It flows southward from 20°S on the east side of Madagascar to the southern limit at Cape Saint Marie and subsequently feeds the Agulhas Current. Its flow is complicated by large cyclonic and anticyclonic eddies.

The East Madagascar Current has a controlling role in the western boundary current of the southwest Indian Ocean together with the Mozambique Current. The mean speed of the East Madagascar Current varies between 0.2–0–9 m/s (0.66–0.00–29.53 ft/s) with a peak in spring and the lowest point in summer. It creates a high-pressure area and affects the Indian Monsoon.

The South Equatorial Current are ocean currents in the Pacific, Atlantic, and Indian Ocean that flow east-to-west between the equator and about 20 degrees south. In the Pacific and Atlantic Oceans, it extends across the equator to about 5 degrees north.

Within the southern hemisphere, the South Equatorial Current is the westward limb of the very large-scale subtropical gyres. These gyres are driven by the combination of trade winds in the tropics and westerly winds that are found south of about 30 degrees south, through a rather complicated process that includes western boundary current intensification.