Impact of extended NAO buoyancy forcing on the subpolar North Atlantic and climate variability over the last millenium

• Main Authors: Myers, Paul G., Yang, Duo
• Format: Other/Unknown Material
• Language: English
• Published: 2007
• Subjects: envir; geo; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.7939/R36M33J3X; https://era.library.ualberta.ca/items/e2275a01-cbe2-4924-a799-f28a5cd852d5

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.