Freshwater export from the Labrador Current to the North Atlantic Current at the Tail of the Grand Banks of Newfoundland
Fratantoni, Paula S.
McCartney, Michael S.
MetadataShow full item record
KeywordLabrador Current; Subpolar gyre; Freshwater; North Atlantic Current; Boundary current retroflection
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.
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.
Showing items related by title, author, creator and subject.
Pickart, Robert S.; Spall, Michael A. (American Meteorological Society, 2007-09)The overturning and horizontal circulations of the Labrador Sea are deduced from a composite vertical section across the basin. The data come from the late-spring/early-summer occupations of the World Ocean Circulation ...
Deshayes, Julie; Curry, Ruth G.; Msadek, Rym (American Meteorological Society, 2014-05-01)The subpolar North Atlantic is a center of variability of ocean properties, wind stress curl, and air–sea exchanges. Observations and hindcast simulations suggest that from the early 1970s to the mid-1990s the subpolar ...
Straneo, Fiamma (American Meteorological Society, 2006-04)The seasonal and interannual variations in the export of Labrador Sea Water (LSW), and in the heat and freshwater transport through the central Labrador Sea, are examined for two different periods: from 1964 to 1974, using ...