The effects of tides on the water mass mixing and sea ice in the Arctic Ocean

• Published in: Journal of geophysical research. Oceans 2015-10, Vol.120 (10), p.6669-6699
• Main Authors: Luneva, Maria V., Aksenov, Yevgeny, Harle, James D., Holt, Jason T.
• Format: Article
• Language: English
• Subjects: Arctic Ocean; Arctic sea ice; Bottom topography; Boundary layers; Computer simulation; Dynamics; Ekman pumping; Entrainment; Geophysics; Ice; Ice environments; Ice volume; Isopycnals; Marine; mixing; NEMO; Ocean currents; Oceanography; Oceans; Reduction; Relative vorticity; Salinity; Salinity effects; Sea ice; Sea surface; Sea surface temperature; Slope; Surface salinity; Surface water; Tidal currents; Tidal dynamics; Tidal effects; Tidal interaction; Tides; Topography; Topography (geology); Trends; Vorticity; water mass; Water mass mixing; Water masses
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/2014JC010310

In this study, we use a novel pan‐Arctic sea ice‐ocean coupled model to examine the effects of tides on sea ice and the mixing of water masses. Two 30 year simulations were performed: one with explicitly resolved tides and the other without any tidal dynamics. We find that the tides are responsible for a ∼15% reduction in the volume of sea ice during the last decade and a redistribution of salinity, with surface salinity in the case with tides being on average ∼1.0–1.8 practical salinity units (PSU) higher than without tides. The ice volume trend in the two simulations also differs: −2.09 × 103 km3/decade without tides and −2.49 × 103 km3/decade with tides, the latter being closer to the trend of −2.58 × 103 km3/decade in the PIOMAS model, which assimilates SST and ice concentration. The three following mechanisms of tidal interaction appear to be significant: (a) strong shear stresses generated by the baroclinic clockwise rotating component of tidal currents in the interior waters; (b) thicker subsurface ice‐ocean and bottom boundary layers; and (c) intensification of quasi‐steady vertical motions of isopycnals (by ∼50%) through enhanced bottom Ekman pumping and stretching of relative vorticity over rough bottom topography. The combination of these effects leads to entrainment of warm Atlantic Waters into the colder and fresher surface waters, supporting the melting of the overlying ice. Key Points: Tides have an important role in mixing in the Arctic This leads to a stronger reduction in sea ice A new pan‐Arctic NEMO model is used to explore this