How Is Meridional Coherence Maintained in the Lower Limb of the Atlantic Meridional Overturning Circulation?
©2018. The Authors. Despite a strong focus on latitudinal continuity of the Atlantic Meridional Overturning Circulation (AMOC) variability, transport continuity in different layers that constitute the AMOC lower limb has received considerably less attention. In this study, we investigate the transport connectivity of Upper North Atlantic Deep Water (UNADW) and Lower NADW (LNADW), with both defined by density. Using two ocean circulation models and an ocean reanalysis, we find that subpolar-originated transport anomalies, particularly for UNADW, do not propagate to the subtropics over a period of five decades. We also find that transports in both layers are linked to AMOC at subpolar latitudes, yet only LNADW transport shows linkage to AMOC in the subtropical gyre. Thus, latitudinal AMOC continuity is likely unrelated to transport continuity in any single layer, but rather a result of connection between subpolar-AMOC and subtropical-LNADW transport. An exception to this generalization is possible with strong LNADW transport events.
Zou, S; Lozier, MS; Buckley, M
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