NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Warm and Saline Events Embedded in the Meridional Circulation of the Northern North AtlanticOcean state estimates from 1958 to 2005 from the Simple Ocean Assimilation System (SODA) system are analyzed to understand circulation between subtropical and subpolar Atlantic and their connection with atmospheric forcing. This analysis shows three periods (1960s, around 1980, and 2000s) with enhanced warm, saline waters reaching high latitudes, alternating with freshwater events originating at high latitudes. It complements surface drifter and altimetry data showing the subtropical -subpolar exchange leading to a significant temperature and salinity increase in the northeast Atlantic after 2001. The warm water limb of the Atlantic meridional overturning cell represented by SODA expanded in density/salinity space during these warm events. Tracer simulations using SODA velocities also show decadal variation of the Gulf Stream waters reaching the subpolar gyre and Nordic seas. The negative phase of the North Atlantic Oscillation index, usually invoked in such variability, fails to predict the warming and salinization in the early 2000s, with salinities not seen since the 1960s. Wind stress curl variability provided a linkage to this subtropical/subpolar gyre exchange as illustrated using an idealized two ]layer circulation model. The ocean response to the modulation of the climatological wind stress curl pattern was found to be such that the northward penetration of subtropical tracers is enhanced when amplitude of the wind stress curl is weaker than normal. In this case both the subtropical and subpolar gyres weaken and the subpolar density surfaces relax; hence, the polar front moves westward, opening an enhanced northward access of the subtropical waters in the eastern boundary current.
Document ID
20120016994
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hakkinen, Sirpa (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rhines, Peter B. (Washington Univ. Seattle, WA, United States)
Worthen, Denise L. (Wyle Information Systems Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
March 4, 2011
Publication Information
Publication: Journal of Geophysical Research
Volume: 116
Subject Category
Meteorology and Climatology
Report/Patent Number
GSFC.JA.6582.2012
Distribution Limits
Public
Copyright
Other