From AMS Glossary
One of the western boundary currents of the North Atlantic subtropical gyre and one of the swiftest ocean currents with one of the largest transports.
A deep, narrow, and swift current, it continues from the Florida Current for 2500 km in a northeastward direction, penetrating into the Atlantic as a free jet. It reaches its maximum transport of 90–150 Sv (90–150 × 106 m3s-1) near 65°W before beginning to lose water to the Sargasso Sea; this water rejoins the Florida Current as the Gulf Stream recirculation. Some 50–90 Sv (50–90 × 106 m3s-1) continue northeastward past the Grand Banks (50°W), where the current is also known as the Gulf Stream Extension and the North Atlantic Current (or North Atlantic Drift). It forms a marked temperature and salinity front with the Labrador Current, which meets the Gulf Stream Extension from the north and then flows parallel to it. As a free jet, the Gulf Stream develops instabilities in the form of meanders that eventually break off as eddies, also known as rings. Cyclonic (cold core) rings contain cold Labrador Current water and drift slowly southwestward into the Sargasso Sea. Anticyclonic (warm core) rings contain warm Sargasso Sea water and drift southwestward in the Slope Water found between the Gulf Stream and the continental shelf.