HR: 0800h
AN: OS21C-1257    [Abstracts]
TI: Spatial and Temporal Variability of Labrador Sea Water Export Pathways
AU: * Mich, N T
EM: ntm20@duke.edu
AF: Duke University, Nicholas School of the Environment and Earth Sciences P.O. Box 90227, Durham, NC 27708 United States
AU: Lozier, M S
EM: mslozier@duke.edu
AF: Duke University, Nicholas School of the Environment and Earth Sciences P.O. Box 90227, Durham, NC 27708 United States
AU: Bower, A S
EM: abower@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Physical Oceanography MS #21 Clark 315A, Woods Hole, MA 02543 United States
AB: Labrador Sea Water (LSW), a critical element of the bottom limb of the Atlantic meridional overturning cell, has been shown to be a particularly sensitive indicator of changes in sea surface conditions on decadal time scales. Though the export of these signals out of the subpolar region is crucial for our understanding of how climate signals spread, the variability of Labrador Sea Water pathways on decadal time scales is not clearly understood. Recent profiling float studies in the subpolar region have shown surprisingly little evidence of an export pathway via the Deep Western Boundary Current (DWBC). Floats launched in the Labrador Sea, including some intentionally placed in the DWBC, did not follow the western boundary to subtropical latitudes, but instead were pulled offshore to drift eastward at the subpolar-subtropical gyre boundary, raising questions addressed by this study, namely: Is there a dominant pathway for waters from the subpolar region to reach the subtropics? Is there temporal variability in the strength or dominance of these pathways? Are these pathways sensitive to climate variability? In this study, we combine data from the Bedford Institute of Oceanography Climate database and from Hydrobase 2, a database of hydrographic profiles, to address these questions. The study area covers most of the North Atlantic, from $30\deg$N to $65\deg$N and from $80\deg$W to $5\deg$W. We have focused on three density surfaces most common to LSW, $\sigma$$_{1.5}$ = 34.62, 34.66, and 34.68 kg m$^{-3}$. We use well-known properties of LSW, including its low temperature, low salinity, low potential vorticity, and high oxygen content, to trace the changing pathways of LSW over time. Understanding these changing pathways is crucial to understanding how the oceans will respond to climate change.
DE: 4215 Climate and interannual variability (3309)
DE: 4532 General circulation
DE: 1635 Oceans (4203)
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting