Pathways and transformation of the Denmark Strait Overflow Water in the Irminger Basin

The Denmark Strait Overflow (DSO) supplies one third of the North Atlantic Deep Water and is a key component of the global thermohaline circulation. Knowledge of the pathways of DSO through the Irminger Basin and its transformation there is still incomplete however. We deploy over 10,000 Lagrangian particles at Denmark Strait in a high resolution ocean model to study these issues. The particle trajectories map the dense water pathways on the continental shelf that are consistent with available observations and these shelf particles contribute significantly to the dense water at the Angmagssalik section (approx. 25%, see Figure). We estimate particle transit time distributions in the Irminger Basin and find that the particles released at the Denmark Strait sill transit the Irminger basin to the Spill Jet section (65.25N) in, typically, 5-7 days and to the Angmagssalik section (63.5N) in two-three weeks. We also identify two places where the water density following particle trajectories decreases rapidly due to intense mixing with waters of Atlantic origin: southwest of the sill and southwest of the Kangerdlugssuaq Trough on the continental slope. Intense mixing occurs also on the shelf, involving the Polar Waters. Finally, we find that the densest waters in the Irminger Basin may originate from the shelf adjacent to the sill, not from the sill itself as previously believed. Our study extends the conceptual view of the DSO in the Irminger Basin, and motivates observational campaigns to verify these results and monitor different pathways of DSO components.

Publication: M. Koszalka, Inga, Thomas W. N. Haine, Marcello G. Magaldi, 2013: Fates and Travel Times of Denmark Strait Overflow Water in the Irminger Basin. J. Phys. Oceanogr., 43, 2611–2628, doi: dx.doi.org/10.1175/JPO-D-13-023.1