This study aims to clarify the connectivity of the subtropical and subpolar North Atlantic by mapping exchange pathways for the upper and lower limbs of the meridional overturning circulation. The work is motivated in part by discrepancies between Eulerian transport estimates and the behavior of floats and drifters in the upper and lower limbs of the MOC. The work will take advantage of the extensive Lagrangian data set that has accumulated from different programs over the past 40 years, as well as of historical hydrographic data and altimetric sea surface heights. The data-based analysis will be augmented by numerical models. Insights into the relationship between kinematics and dynamics will result from comparisons of barriers with the potential vorticity field. Finally, an improved understanding of residence times for the waters comprising the upper and lower limbs of the overturning circulation should be forthcoming.
The connectivity between the subpolar and subtropical North Atlantic constitutes an important piece of the global ocean circulation and climate system. Because the meridional transport of heat and carbon in both the upper and deep ocean depends crucially on the linkage between these gyres, predictions of climate change will benefit from a better understanding of this complex link. The physical oceanographic community at large may also benefit from an illustration of the strengths and weaknesses of the dynamical systems techniques described herein. They have been applied to smaller scale flows and to idealizations of basin scale flows in the past, but never to a flow field of the scale and complexity of the North Atlantic wind-driven gyres and MOC.
