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Heat and Freshwater Through The Labrador Sea
Like much of the
subpolar region, the Labrador Sea
experiences a net heat loss to the atmosphere. On a yearly average,
this heat loss amounts to approximately 2GJ of net heat loss per square
meter which has to be balanced by a supply of heat by the ocean
circulation. This heat is advected into the Labrador Sea via its
boundary currents, and supplied to the interior region (where the bulk
of the dense water formation occurs) by eddies. Similarly, freshwater
of Arctic origin is advected around the basin by the surface boundary
currents and advected into the interior via instabilities/eddy fluxes.
This freshwater is mixed vertically during convection, and partly
removed with the export of the fresh, cold, dense Labrador Sea Water
that is produced during convection.
To first order, for the ocean to be in steady state,
one would expect
the heat and freshwater transports through the Labrador Sea to balance
on an annual basis. In practice, however, there occur large variations
in the heat and freshwater transports through the basin which, in turn,
affect the water column's stability and its ability to undergo deep
convection.
 The net seasonal
cycle of heat and freshwater through the central Labrador Sea, and
their interannual variations are examined using historical (1964-1974)
and modern (1996-2000) data (see Figure). The historical data were
collected at Ocean Weather Station Bravo in the central Labrador Sea,
while the modern time series were constructed using profiling float
data, mostly concentrated in the central region.
Note the shutdown of deep convection recorded from
1969 to 1972,
resulting in an increase of heat and salt in the sub-surface waters.
See:
Straneo, F., 2006: Heat and Freshwater
Transport through the Central Labrador Sea.
J. Phys. Ocean.,36(4), 606-628.
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