Can polar lows lead to a warming of the ocean surface?

Authors: SAETRA, O.; LINDERS, T.; DEBERNARD, J.B.

Source: Tellus A, Volume 60, Number 1, January 2008 , pp. 141-153(13)

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Abstract:

Possible surface warming by strong wind-forcing from polar lows in the North-Atlantic has been investigated using a numerical model for vertical entrainment of waters from a subsurface warm core, and microwave satellite images of sea-surface temperature during polar low events. The hypothesis is based on the frequently observed subsurface warm core in oceans influenced by the North-Atlantic current (NAC) or by outflowing surface water from the Arctic Ocean. CTD-soundings from the Nordic Seas reveal that the waters from the NAC are located under colder and less saline surface waters in winter. For sufficiently strong wind events, turbulent entrainment of this subsurface warm core may lead to a rapid surface warming. Our main findings is that the surface warming of more than 1 °C may take place within a few hours. The result is based on model runs with initial temperature and salinity profiles from CTD-observations. Observational evidence of surface temperatures that support the hypothesis are found in microwave satellite observations from a polar low event. In the case presented here, increased sea-surface temperatures between 1 and 2 °C were observed. We believe that rapid surface warming of this magnitude may be a potential positive feedback mechanism for the cyclone intensity.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0870.2007.00279.x

Affiliations: 1: The Norwegian Meteorological Institute, PO Box 43 blindern, 0313 Oslo, Norway

Publication date: 2008-01-01