2012 Project Summary Pathways of Meridional Circulation in the Ocean Climate System

• Main Authors: Pis Peter Rhines, Sirpa Häkkinen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: doi; 10.1029/2010JC006275; Curl; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.434.795; http://www.usclivar.org/sites/default/files/amoc/Rhines_2012AMOC_projsum.pdf

Our goal is to understand the variability of the upper limb of the AMOC such as the recent intense warming and salinization of the subpolar North Atlantic after year 2000. This subpolar warming coincides with a warm phase of the Atlantic Multidecadal Variability (AMV). Recent Results (1) In SODA assimilation data we identified three periods (1960s, 1980 and 2000s) with enhanced warm, saline Gulf Stream waters reaching high latitudes. Atmospheric forcing of these warm events was analyzed by focusing on the wind stress curl. The second mode, the gyre mode, which represents amplitude fluctuations of the climatological wind stress curl pattern, was found to be important for the northward penetration of warm subtropical waters acting through weakening gyre circulation. (2) We extended the analysis of the wind stress curl variability using a 20 th century reanalysis (Compo et al. 2011) to develop linkages to the AMV. Our findings can be summarized as follows: the gyre mode represents strengthening and weakening of blocking activity in the northern North Atlantic and the associated storm track changes; decades of