Cross-Isobath Freshwater Exchange Within the North Atlantic Subpolar Gyre

• Main Authors: Pennelly, Clark, Hu, Xianmin, Myers, Paul G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Boundary currents; Freshwater; Labrador Sea; Numerical modeling; Stratification; Greenland; North Atlantic
• Online Access: https://era.library.ualberta.ca/items/cc3488d3-9ca2-48f0-9d1f-ed5d95493c9e; https://doi.org/10.7939/r3-m2mk-3n64

The amount of cross‐isobath freshwater exchange within the North Atlantic subpolar gyre is estimated from numerical modelling simulations. A regional configuration of the Nucleus for European Modelling of the Ocean model is used to carry out three simulations with horizontal resolutions of 1/4°, 1/12°, and 1/4° with a 1/12° nested domain. Freshwater transport is calculated across five isobaths in six regions for three distinct water masses. Fresh Polar Water is only transported offshore from the western coast of Greenland and the southern coast of Labrador; other regions have onshore transport of freshwater or little offshore transport. The salty water masses of Irminger and Labrador Sea Water typically have onshore transport, acting to promote subsurface freshening of the Labrador Sea. The freshwater transport via the Polar Water mass experiences a large degree of seasonal variability, while the Irminger and Labrador Sea Water masses do not. Decomposing the freshwater transport into the mean and turbulent components indicates that most regions and water masses have stronger freshwater transport associated with the mean flow while the turbulent flow in often the opposite direction. The only water mass and region where the mean and turbulent freshwater transport act in the same direction is Polar Water along the western margin of Greenland. Model resolution plays an important role in determining cross‐isobath exchange as our results from an identically forced simulation at 1/4° has reduced seasonal cycles, reduced transport, and sometimes transport in the opposite direction when compared against the 1/12° resolution simulations.