Labrador Sea Water is an intermediate water mass in the

Labrador Sea The Labrador Sea (; ) is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelf, continental shelves to the southwest, northwest, and northeast. It connects to the north with Baffi ...

. It is characterized by cold water, relatively low

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

compared to other intermediate water masses, and high concentrations of both

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and anthropogenic tracers.Pickart, Robert S., et al. "Is Labrador Sea Water formed in the Irminger basin?" Deep-Sea Research Part I: Oceanographic Research Papers 50.1 (2003): 23-52 It is formed by convective processes Yashayaev, I.M., et al. "Recent Decline of the Labrador Sea Water." Bedford Institute of Oceanography, 2000 located between

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

and the northeast coast of the

Labrador Peninsula The Labrador Peninsula, also called Quebec-Labrador Peninsula, is a large peninsula in eastern Canada. It is bounded by Hudson Bay to the west, the Hudson Strait to the north, the Labrador Sea to the east, Strait of Belle Isle and the Gulf of ...

. Deep convection in the Labrador Sea allows colder water to sink forming this water mass, which is a contributor to the upper layer of

North Atlantic Deep Water North Atlantic Deep Water (NADW) is a deep water mass formed in the North Atlantic Ocean. Thermohaline circulation (properly described as meridional overturning circulation) of the world's oceans involves the flow of warm surface waters from the ...

. North Atlantic Deep Water flowing southward is integral to the

Atlantic Meridional Overturning Circulation The Atlantic meridional overturning circulation (AMOC) is the main ocean current system in the Atlantic Ocean.IPCC, 2021Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Sem ...

. The Labrador Sea experiences a net heat loss to the atmosphere annually.

Formation

Convection in the Labrador Sea is the result of cyclonic circulation of the sea currents and cyclonic atmospheric forcing. At the southern tip of

, water enters the West Greenland Current from the East Greenland Current, continues to flow northwest around

Baffin Bay Baffin Bay (Inuktitut: ''Saknirutiak Imanga''; ; ; ), located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arctic Ocean. It is sometimes considered a s ...

, and then southeast into the Baffin Island Current, continuing in the same direction in the Labrador Current.

Sea ice Sea ice arises as seawater freezes. Because ice is less density, dense than water, it floats on the ocean's surface (as does fresh water ice). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans. Much of the world' ...

in the winter months inhibits surface flow into Baffin Bay. The Labrador Current and the Western Greenland Current flow in opposite directions, creating a cyclonic eddy. During winter months low pressure dominates in this region, and in years with a positive North Atlantic Oscillation deeper convection is observed.

Spreading

Labrador Sea Water spreads through the North Atlantic Ocean by three routes: northeast directly into Irminger Sea, into the eastern North Atlantic by means of the deep North Atlantic current, and meridionally via the Deep Western Boundary Current. A 2002 study presented data that suggest that the Labrador Sea is not the only formation site for Labrador Sea Water. They observed similar convective processes in Irminger Sea and noted that transit times for Labrador Sea Water into Irminger Sea were unusually fast, suggesting that Irminger Sea as another source.

Seasonality

Labrador Sea Water reflects seasonal and interannual variations. In late spring and summer, large amounts of cold freshwater accumulate from melting ice and are mixed downward during convection. The source for heat in the Labrador Sea is modified North Atlantic Current water after circulating the subpolar gyre.Straneo, F. "Heat and Freshwater Transport through the Central Labrador Sea." Journal of Physical Oceanography 36 (2005) In winter the sea becomes more saline as freshwater freezes to form sea ice. The greatest seasonal variability is largely confined to the surface waters, however an annual cycle of convective mixing and re-stratification is observed throughout the water column. Warming and increased salinity in the lower level and freshening at the surface is associated with re-stratification (May–December), whereas a convective mixing period (January–April) leads to cooling and a decrease in salt content in intermediate and deep waters and an increase in salt content at the surface. Interannual variations in the intermediate Labrador Sea Water are due largely to changes in convection throughout these periods. Weak convective periods are associated with more heat in the water column and deep convective periods are characterized by cold water. In the early 1990s, consecutive severe winters contributed towards deep convection in the Labrador Sea. These winters were associated with strong positive fluctuations in the North Atlantic Oscillation. Labrador Sea Water became cold, fresh, and dense during this period, and the layer extended to depths of in the spring of 1994. Due to weakened convection, Labrador Sea Water began warming significantly and increased in salinity over the following decade. This trend continued through 2010 and 2011 when weak convection was observed in relation with negative North Atlantic Oscillation. Deep convection was observed again in 2012 with Labrador Sea Water reaching 1400 m, corresponding with a positive North Atlantic Oscillation similar to those seen in the early 1990s.

References

{{reflist Oceanography

Formation

Spreading

Seasonality

See also

References