Temporal Variability of the Labrador Current Pathways Around the Tail of the Grand Banks at Intermediate Depths in a High-Resolution Ocean Circulation Model

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The Northwest Atlantic Shelf and Slope have warmed dramatically in the past decade, changing marine life and challenging fisheries management. A rapid warming event in 2009/2010, linked to a reduced supply of cold water from the Labrador Sea, pushed this region to a new state of unprecedentedly high temperatures that persists today. However, a mechanistic understanding of how the Labrador Current connectivity is reduced at the Tail of the Grand Banks of Newfoundland has been lacking. Here, we present the results of a 25-year (1993–2017) Lagrangian analysis using the HYbrid Coordinate Ocean Model. Synthetic particles were released in the vicinity of the Labrador Current upstream of the Grand Banks and tracked in a 2-D velocity field. We found that the Labrador Current can be completely blocked by Gulf Stream eddies and meanders that impinge on the shelf break along the Grand Banks. This blocking can occur in many different locations at, upstream, or downstream of the Tail of the Grand Banks, since the Labrador Current needs a clear passage over a long distance to continue its path. In the simulation, the Labrador Current has been blocked more often since 2008, which led to the warming of the Northwest Atlantic Shelf and Slope. These results, which are consistent with satellite observations, can provide predictability for the New England and Nova Scotia shelf environments potentially helpful for ecosystem management.

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Journal of Geophysical Research: Oceans