Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 57 (2010): 258-283, doi:10.1016/j.dsr.2009.11.006.
Description:
Historical hydrographic data, spanning the period 1896-2006, are used to examine the annual
mean and seasonal variations in the distribution of freshwater along and across the shelf/slope
boundary along the Labrador and Newfoundland Shelves and the Grand Banks of
Newfoundland. Particular attention is paid to the export of freshwater along the eastern Grand
Banks, between Flemish Cap and the Tail of the Grand Banks, as this has long been identified as
a preferential region for the loss of mass and freshwater from the boundary. The data are
combined into isopycnally averaged long-term annual and monthly mean gridded property fields
and the evolving distribution of fresh arctic-origin water is analyzed in fields of salinity anomaly,
expressed as departures from the “central water” temperature-salinity relation of the Gulf
Stream. The climatology confirms that cold/fresh northern-source waters are advected offshore
within the retroflecting Labrador Current along the full length of the boundary between Flemish
Cap and the Tail of the Grand Banks. In fact, it is estimated that most of the equatorward
baroclinic transport at the boundary must retroflect back toward the north in order to explain the
annual mean distribution of salinity in the climatology. While the retroflection of the Labrador
Current appears seasonally robust, the freshwater distribution within the retroflection region
varies in response to (1) the freshness of the water available for export which is set by the arrival
and rapid flushing of the seasonal freshwater pulse at the boundary, (2) seasonal buoyancy
forcing at the surface which alters the vertical stratification across the retroflection region,
restricting certain isopycnal export pathways, and (3) the density structure along the eastern
Grand Banks, which defines the progressive retroflection of the Labrador Current.
Description:
This work was supported by a grant
from the Woods Hole Oceanographic Institution’s Ocean and Climate Change Institute (PF) and
by the National Science Foundation under grant OCE-0550423 (PF and MM).
Keywords:
Labrador Current
;
Subpolar gyre
;
Freshwater
;
North Atlantic Current
;
Boundary current retroflection
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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