Open AccessImpact of extended NAO buoyancy forcing on the subpolar North Atlantic and climate variability over the last millenium
Author(s) -
Yang Duo,
Myers Paul G.
Publication year - 2007
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1029/2007pa001439
Subject(s) - atlantic multidecadal oscillation , climatology , forcing (mathematics) , north atlantic oscillation , shutdown of thermohaline circulation , buoyancy , atlantic equatorial mode , north atlantic deep water , thermohaline circulation , geology , oceanography , general circulation model , climate change , physics , quantum mechanics
We examine the impact of forcing a regional eddy‐permitting ocean model of the subpolar North Atlantic with anomalous buoyancy fluxes corresponding to extended extreme states of the North Atlantic Oscillation (NAO). We find a weakened (enhanced) Meridional Overturning Circulation (MOC) in our low (high) NAO simulations. Such results may be consistent with ideas that suggest the Medieval Warm Period (MWP) and the Little Ice Age are associated with periods when the NAO is predominantly in one phase. Our results also show multidecadal MOC variability with a period of 70 years in our high‐NAO simulation, in comparison to an equilibrium‐like circulation under low‐NAO related forcing. A less stable climatic state is therefore suggested to occur under high‐NAO forcing, which may be consistent with ideas that suggest the warming associated with the MWP did not occur synchronously over the North Atlantic. The variability appears to be brought about by internal oceanic processes.