The sea formed upon separation of theNorth American Plate andGreenland Plate that started about 60 million years ago and stopped about 40 million years ago. It contains one of the world's largestturbidity current channel systems, theNorthwest Atlantic Mid-Ocean Channel (NAMOC), that runs for thousands of kilometers along the sea bottom toward the Atlantic Ocean.
The Labrador Sea is a major source of theNorth Atlantic Deep Water, a cold water mass that flows at great depth along the western edge of the North Atlantic.
Map showing the Labrador Sea according to the IHO definition
Between about 500 BC and 1300 AD, the southern coast of the sea containedDorset,Beothuk, andInuit settlements; Dorset tribes were later replaced byThule people.[6]
Natural Resources Canada uses a slightly different definition, putting the northern boundary of the Labrador Sea on a straight line from a headland onKilliniq Island abutting Lady Job Harbour to Cape Farewell.[8]
The Labrador Sea is about 3,400 m (1,859fathoms; 11,155feet) deep and 1,000 km (621miles; 540nautical miles) wide where it joins the Atlantic Ocean. It becomes shallower, to less than 700 m (383 fathoms; 2,297 ft) towards Baffin Bay (seedepth map) and passes into the 300 km (190 mi; 160 nmi) wideDavis Strait.[2] A 100–200 m (55–109 fathoms; 330–660 ft) deepturbidity current channel system, which is about 2–5 km (1.2–3.1 mi; 1.1–2.7 nmi) wide and 3,800 km (2,400 mi; 2,100 nmi) long, runs on the bottom of the sea, near its center from theHudson Strait into the Atlantic.[9][10] It is called theNorthwest Atlantic Mid-Ocean Channel (NAMOC) and is one of the world's longest drainage systems of Pleistocene age.[11] It appears as a submarine river bed with numerous tributaries and is maintained by high-density turbidity currents flowing within thelevees.[12]
The water temperature varies between −1 °C (30 °F) in winter and 5–6 °C (41–43 °F) in summer. The salinity is relatively low, at 31–34.9 parts per thousand. Two-thirds of the sea is covered in ice in winter. Tides aresemi-diurnal (i.e. occur twice a day), reaching 4 m (2.2 fathoms; 13 ft).[1]
There is an anticlockwise water circulation in the sea. It is initiated by theEast Greenland Current and continued by theWest Greenland Current, which brings warmer, more saline waters northwards, along the Greenland coasts up to the Baffin Bay. Then, theBaffin Island Current andLabrador Current transport cold and less saline water southward along the Canadian coast. These currents carry numerous icebergs and therefore hinder navigation and exploration of the gas fields beneath the sea bed.[3][13] The speed of the Labrador current is typically 0.3–0.5 m/s (0.98–1.64 ft/s), but can reach 1 m/s (3.3 ft/s) in some areas,[14] whereas the Baffin Current is somewhat slower at about 0.2 m/s (0.66 ft/s).[15] The Labrador Current maintains the water temperature at 0 °C (32 °F) and salinity between 30 and 34 parts per thousand.[16]
The sea provides a significant part of theNorth Atlantic Deep Water (NADW) — a cold water mass that flows at great depth along the western edge of the North Atlantic, spreading out to form the largest identifiable water mass in theWorld Ocean.[17] The NADW consists of three parts of different origin and salinity, and the top one, the Labrador Sea Water (LSW), is formed in the Labrador Sea. This part occurs at a medium depth and has a relatively low salinity (34.84–34.89 parts per thousand), low temperature (3.3–3.4 °C (37.9–38.1 °F)) and high oxygen content compared to the layers above and below it. LSW also has a relatively low vorticity, i.e. the tendency to form vortices, than any other water in North Atlantic that reflects its high homogeneity. It has apotential density of 27.76–27.78 mg/cm3 relatively to the surface layers, meaning it is denser, and thus sinks under the surface and remains homogeneous and unaffected by the surface fluctuations.[18]
^Reinhard Hesse And Allan Rakofsky (1992). "Deep-Sea Channel/Submarine-Yazoo System of the Labrador Sea: A New Deep-Water Facies Model (1)".AAPG Bulletin.76.doi:10.1306/BDFF88A8-1718-11D7-8645000102C1865D.
^abKenneth F. Drinkwater, R. Allyn Clarke."Labrador Sea".The Canadian Encyclopedia.Archived from the original on 2 August 2018. Retrieved3 February 2008.
