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The impact of the North Atlantic Oscillation on the uptake and accumulation of anthropogenic CO 2 by North Atlantic Ocean mode waters
Author(s) -
Levine Naomi Marcil,
Doney Scott C.,
Lima Ivan,
Wanninkhof Rik,
Bates Nicholas R.,
Feely Richard A.
Publication year - 2011
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2010gb003892
Subject(s) - oceanography , north atlantic oscillation , atlantic multidecadal oscillation , environmental science , gulf stream , thermohaline circulation , north atlantic deep water , atlantic equatorial mode , geology
The North Atlantic Ocean accounts for about 25% of the global oceanic anthropogenic carbon sink. This basin experiences significant interannual variability primarily driven by the North Atlantic Oscillation (NAO). A suite of biogeochemical model simulations is used to analyze the impact of interannual variability on the uptake and storage of contemporary and anthropogenic carbon ( C anthro ) in the North Atlantic Ocean. Greater winter mixing during positive NAO years results in increased mode water formation and subsequent increases in subtropical and subpolar C anthro inventories. Our analysis suggests that changes in mode water C anthro inventories are primarily due to changes in water mass volumes driven by variations in water mass transformation rates rather than local air‐sea CO 2 exchange. This suggests that a significant portion of anthropogenic carbon found in the ocean interior may be derived from surface waters advected into water formation regions rather than from local gas exchange. Therefore, changes in climate modes, such as the NAO, may alter the residence time of anthropogenic carbon in the ocean by altering the rate of water mass transformation. In addition, interannual variability in C anthro storage increases the difficulty of C anthro detection and attribution through hydrographic observations, which are limited by sparse sampling of subsurface waters in time and space.