Publication Date:
2022-05-25
Description:
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.
Description:
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.
Description:
Financial support for the early observations (2001-2004) was provided by
the G. Unger Vetlesen Foundation. Observations collected as part of the Line
Wprogram (2004-2008) were funded by the U.S. National Science Foundation
(grants number OCE-0241354 and OCE-0726720) as well as funding from
WHOI’s Ocean and Climate Change Institute.
Keywords:
Deep Western Boundary Current
;
Labrador Sea Water
;
Variability
;
Transport
;
Potential vorticity
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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