Seasonal and Interannual Variations of Irminger Ring Formation and Boundary–Interior Heat Exchange in FLAME

• Published in: Journal of Physical Oceanography
• Main Authors: de Jong, M.F., Bower, A.S., Furey, H.H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Labrador Sea
• Online Access: https://www.vliz.be/imisdocs/publications/86/292486.pdf

The contribution of warm-core anticyclones shed by the Irminger Current offWestGreenland, known asIrminger rings, to the restratification of the upper layers of the Labrador Sea is investigated in the 1/ 128Family of Linked Atlantic Models Experiment (FLAME) model. The model output, covering the 1990–2004 period, shows strong similarities to observations of the Irminger Current as well as ring observationsat a mooring located offshore of the eddy formation region in 2007–09. An analysis of fluxes in the modelshows that while the majority of heat exchange with the interior indeed occurs at the site of the IrmingerCurrent instability, the contribution of the coherent Irminger rings is modest (18%). Heat is provided tothe convective region mainly through noncoherent anomalies and enhanced local mixing by the ringsfacilitating further exchange between the boundary and interior. The time variability of the eddy kineticenergy and the boundary to interior heat flux in the model are strongly correlated to the density gradientbetween the dense convective region and the more buoyant boundary current. In FLAME, the densityvariations of the boundary current are larger than those of the convective region, thereby largely controllingchanges in lateral fluxes. Synchronous long-term trends in temperature in the boundary and theinterior over the 15-yr simulation suggest that the heat flux relative to the temperature of the interior islargely steady on these time scales.