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Changes in the pool of Labrador Sea Water in the subpolar North Atlantic
Author(s) -
Kieke Dagmar,
Rhein Monika,
Stramma Lothar,
Smethie William M.,
Bullister John L.,
LeBel Deborah A.
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl028959
Subject(s) - ocean gyre , baroclinity , north atlantic deep water , north atlantic oscillation , oceanography , climatology , geology , water mass , circumpolar deep water , subtropics , thermohaline circulation , fishery , biology
Measurements of chlorofluorocarbon inventories during 1997–2003 allow the detection and quantification of significant changes in the formation rates of two modes of Labrador Sea Water (LSW): Upper (ULSW) and deep LSW, both here defined in fixed density intervals. Both modes contribute to the cold limb of the Meridional Overturning Circulation. Results reveal that the lighter ULSW formed since the mid‐1990s has started to replace the large pool of the deep LSW stored in the western North Atlantic. Formation of deep LSW was absent in 1997–2003. Formation of ULSW compensated for this absence during 1998/99 (7.9 Sv), but afterwards significantly declined to 2.5 Sv. The decrease of the overall LSW formation throughout 1997–2003 correlates with a declining eastward baroclinic mass transport between the centers of the subpolar and subtropical gyres since 1997, a warming of LSW, and a gradually decreasing North Atlantic Oscillation index after 1999.