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Abstract Because new observations have revealed that the Labrador Sea is not the primary source for waters in the lower limb of the Atlantic Meridional Overturning Circulation (AMOC) during the Overturning in the Subpolar North Atlantic Programme (OSNAP) period, it seems timely to re‐examine the traditional interpretation of pathways and property variability for the AMOC lower limb from the subpolar gyre to 26.5°N. In order to better understand these connections, Lagrangian experiments were conducted within an eddy‐rich ocean model to track upper North Atlantic Deep Water (uNADW), defined by density, between the OSNAP line and 26.5°N as well as within the Labrador Sea. The experiments reveal that 77% of uNADW at 26.5°N is directly advected from the OSNAP West section along the boundary current and interior pathways west of the Mid‐Atlantic Ridge. More precisely, the Labrador Sea is a main gateway for uNADW sourced from the Irminger Sea, while particles connecting OSNAP East to 26.5°N are exclusively advected from the Iceland Basin and Rockall Trough along the eastern flank of the Mid‐Atlantic Ridge. Although the pathways between OSNAP West and 26.5°N are only associated with a net formation of 1.1 Sv into the uNADW layer, they show large density changes within the layer. Similarly, as the particles transit through the Labrador Sea, they undergo substantial freshening and cooling that contributes to further densification within the uNADW layer.
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Surface Pathways Connecting the South and North Atlantic Oceans
Abstract The North Brazil Current (NBC) is considered a bottleneck in the South Atlantic, responsible for carrying upper‐ocean waters into the North Atlantic. This work explores the surface pathways connecting the NBC and 26°N in the North Atlantic. To identify said pathways, we use observational trajectories from surface drifters in conjunction with transition path theory applied on a Markov chain. The pathways are computed as ensembles of paths transitioning directly between the NBC and 26°N. Our results suggest that there are two dominant surface pathways: The first is the traditional pathway through the Caribbean Sea and Gulf of Mexico, carrying waters to the Florida Current, while the second is a direct route east of the Caribbean supplying waters to the Antilles Current and basin interior. The latter is composed of multiple pathways that are collectively more probable than the traditional pathway.
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- PAR ID:
- 10385517
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 1
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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