The cold Labrador Current originates in the extremely cold water of the Sub-Polar Region. It flows through the Baffin Bay and the Davis Strait. This cold current continues its southward journey along the east coast of North America up to the Cape Cod.
The origin of this current, according to Munk, was due to the wind-stress torque between the westerlies of middle-latitudes and the polar easterlies.
A south ward-setting western-boundary current is essential to balance the tendency for a northward movement of waters on the pole-ward side of the North Atlantic Drift.
There are two main reasons why this current is extremely cold. The first reason is that the source of this current lies in the Arctic Ocean, where the surface temperature is very low, about the freezing point.
The second reason is that there are thousands of icebergs in this current. Besides, this current is reinforced by currents carrying extremely cold Arctic water through the sounds between the islands to the west of Greenland.
Part of the West Greenland Current turns round when approaching Davis Strait and joins the Labrador Current. According to Smith, Soule, and Mosby, the outflow along the coast of Labrador amounts to 5.6 million m3/sec. above a depth of 1500 meters.
On the continental shelf off Labrador the temperature of the surface water is 0°C and the salinity is less than 34%0. Of course, there are seasonal variations in the surface temperature of this current.
In spring months, a large number of icebergs, nearly all of them broken from the snouts of glaciers of Greenland, are carried along the Labrador Current up to the Grand Banks.
The icebergs reach farthest south off the Grand Banks of Newfoundland in the months of March, April, May, and June. These icebergs are a constant source of menace to shipping.
The Titanic disaster which took place in 1912 is well known. Since then the International Ice Patrol was established to safeguard the shipping. Where this current meets the Gulf Stream System eddies develop along its margins.
Some of the cold water brought down by this current mixes with the warm Gulf Stream, while some sinks down as sub-surface current below the Gulf Stream.
Because of the cold water of the Labrador Current, there is a rapid fall in the temperature, and its influence extends up to Massachusetts, U.S.A. It may be stated that the sub-surface flow of cold and dense water affects the entire deep sea circulation of the Atlantic Ocean.