Gulf Stream

(oceanography) A relatively warm, well-defined, swift, relatively narrow, northward-flowing ocean current which originates north of Grand Bahama Island where the Florida Current and the Antilles Current meet, and which eventually becomes the eastward-flowing North Atlantic Current.

A great ocean current transporting about 70,000,000 tons (63,000,000 metric tons) of water per second (1000 times the discharge of the Mississippi River) northward from the latitude of Florida to the Grand Banks off Newfoundland. The Gulf Stream is thought of as a portion ofa great horizontal circulation in the ocean, where each particle of water executes a closed circuit, sometimes moving slowly in midocean regions and other times rapidly in strong currents like the Gulf Stream. Thus the beginning and end of the Stream have arbitrary geographical limits. See also Atlantic Ocean.

The Gulf Stream is a narrow (62 mi or 100 km) and swift (up to 5 knots or 250 cm/s) eastward-flowing current jet which is embedded in a weaker and broader mean westward flow and which issurrounded by intense eddies. As it leaves the coast at Cape Hatteras, the Stream meanders fromside to side like a river.

The near-surface Gulf Stream transports warm water from southern latitudes eastward to the Grand Banks, where the flow becomes broader and weaker, separating into several branches and eddies. About half the near-surface flow continues eastward across the Mid-Atlantic Ridge, and half recirculates southwestward, with part of the recirculation consisting of a countercurrent located south of the Stream.

The Gulf Stream is predominantly driven by the large-scale wind pattern, the westerlies in the north and the trades in the south. The winds exert a torque on the ocean that, due to the shape and rotation of the Earth, causes a large western-intensified gyre. Cold, deep water is formed in northern seas and flows southward as a western boundary current; warm water flows northward and replaces it. See also Ocean circulation.