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Abstract

The Atlantic Meridional Overturning Circulation (AMOC) in the subpolar North Atlantic has vital impacts on global climate. This study diagnoses the AMOC characteristics using a high resolution data assimilative reanalysis product. Its results are evaluated against the latest observations collected by trans-basin mooring arrays. The meridional volume transport across the section from Greenland to Scotland(i.e., the East Section) is much stronger than that in the Labrador Sea(i.e., the West Section). While the boundary currents in the Labrador Sea show substantial seasonal changes, their compensations yield a very weak seasonality in the AMOC strength. On the other hand, the AMOC across the East section has an apparent seasonal cycle with density changes in the Irminger Basin playing a dominant role. The AMOC interannual variations have comparable amplitudes in both West and East sections. In addition, we further split the AMOC fluctuations into components associated with barotropic and baroclinic processes. The decomposed fields indicate that the isopycnal layer thickness west of Greenland is the primary factor to modulate the AMOC interannual variability across the West section. The AMOC interannual variability across the East section is mostly determined by barotropic velocity changes near the pathway of the North Atlantic Current.