Recent changes in the Labrador Sea Water within the Deep Western Boundary Current southeast of Cape Cod
Joyce, Terrence M.
Toole, John M.
MetadataShow full item record
KeywordDeep Western Boundary Current; Labrador Sea Water; Variability; Transport; Potential vorticity
Water properties measured by the central mooring in the Line W mooring array southeast of Cape Cod document a large character shift during the period of November 2001 to April 2008. The observed temperature, salinity and planetary potential vorticity (PPV) anomalies manifest changes in the formation region of the water masses present at Station W, specifically upper Labrador Sea Water (uLSW), deep Labrador Sea Water (dLSW) and Overflow Water (OW). During the observation period, the minimum in the PPV anomaly field relative to the record mean PPV profile migrated from 1500m, where it was originally found, to 700m. Temporal changes in the vertical distribution of temperature and salinity were correlated with the PPV changes. This suggests a dLSW-dominated first half of the record, versus an uLSW-dominated second half. The structure of these anomalies is consistent with observations within the Labrador Sea, and their transit time to Line W agrees well with tracer-derived times for signals spreading along the western boundary. In that context, the observed water properties at Line W in the early 2000s reflected the intense deep convection in the Labrador Sea in the mid 1990s, with less intense convection subsequently affecting lighter isopycnals. The observed velocity field is dominated by high-frequency (periods of days to months) fluctuations, however, a fraction of the velocity variability is correlated with changes in water mass properties, and indicate a gradual acceleration of the southwestward flow, with a corresponding increase in Deep Western Boundary Current transport.
Author Posting. © The Author(s), 2011. 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 58 (2011): 1019-1030, doi:10.1016/j.dsr.2011.07.006.
Showing items related by title, author, creator and subject.
Palter, Jaime B.; Lozier, M. Susan; Lavender, Kara L. (American Meteorological Society, 2008-05)Labrador Sea Water (LSW), a dense water mass formed by convection in the subpolar North Atlantic, is an important constituent of the meridional overturning circulation. Understanding how the water mass enters the deep ...
Intermediate water links to Deep Western Boundary Current variability in the subtropical NW Atlantic during marine isotope stages 5 and 4 Evans, H. K.; Hall, Ian R.; Bianchi, G. G.; Oppo, Delia W. (American Geophysical Union, 2007-08-02)Records from Ocean Drilling Program Sites 1057 and 1059 (2584 m and 2985 m water depth, respectively) have been used to reconstruct the behavior of the Deep Western Boundary Current (DWBC) on the Blake Outer Ridge (BOR) ...
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. (2009-11)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 ...