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Climatic variability in upper ocean ventilation rates diagnosed using chlorofluorocarbons
Author(s) -
Doney Scott C.,
Bullister John L.,
Wanninkhof Rik
Publication year - 1998
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 - 10.1029/98gl00844
Subject(s) - ocean gyre , chlorofluorocarbon , hydrography , zonal and meridional , environmental science , climatology , water mass , oceanography , mode water , subtropics , convection , water column , atmospheric sciences , geology , meteorology , physics , fishery , biology
The chlorofluorocarbon CFC‐12 (CCl 2 F 2 ) distributions from two occupations of a meridional hydrographic section in the eastern North Atlantic are used to describe the oceanic penetration of CFCs and change in the integrated ventilation patterns over the five years from 1988 to 1993. The CFC‐12 water‐column inventories increased by 30–40%, despite a slowing atmospheric growth rate (14%), because of continuing uptake by undersaturated subsurface water masses whose response is lagged by the ventilation time‐scales. After removing the long‐term CFC temporal trend using a tracer age based normalization technique, we observe a distinct dipole pattern in upper ocean ventilation, with reduced convection in the subpolar gyre and enhanced production of saline subtropical underwater in 1993. These differences are discussed in relation to interannual variability in atmospheric surface forcing, upper ocean anomalies, and convection patterns associated with the North Atlantic Oscillation.