Contrasting response of the eastern and western North Atlantic to an episodic climate event

Author: Ayan H. Chaudhuri
September 1, 2011
Journal Article
Journal of Physical Oceanography

Chaudhuri, Ayan H., Avijit Gangopadhyay, James J. Bisagni, 2011: Contrasting Response of the Eastern and Western North Atlantic Circulation to an Episodic Climate Event*. J. Phys. Oceanogr., 41, 1630–1638.

Regional observational studies in the North Atlantic have noted significant hydrographical shifts in 1997–98 because of the episodic drop in the North Atlantic oscillation (NAO) during 1996. Investigation using a basin-scale model finds that, although the western North Atlantic (WNA) witnessed unusually low-salinity water by 1997, the eastern North Atlantic (ENA) simultaneously evidenced intrusions of high-salinity water at intermediate depths. This study shows that a major source of high salinity in the ENA is from the northward penetration of Mediterranean Outflow Water (MOW) that occurred concurrently with a westward shift of the subpolar front. The authors confirm that the low-salinity intrusion in the WNA is from enhanced Labrador Current flow. Results from climatological high- and low-NAO simulations suggest that the NAO-induced circulation changes that occurred in 1997–98 are a characteristic North Atlantic basin response to different forcing conditions during characteristic high- and low-NAO periods.