Australia: The Land Where Time Began

A biography of the Australian continent 

Atlantic Ocean - Northeast Circulation Impacted by Mesoscale Polar Storms

Deep water formation in the subpolar North Atlantic Ocean is regulated by atmospheric processes, which means the large-scale circulation of the ocean is influenced by these atmospheric processes (Marshall & Schott, 1999). This climatically sensitive region of the Atlantic Ocean is passed over by thousands of mesoscale storms, aka polar lows, every year, and many of these storms are not picked up by meteorological reanalyses or numerical models as they are either too small or too short-lived (Condron et al., 2006; Kolstad, 2008; Zahn & von Storch, 2010. In this article the authors1 present the results of simulations that they carried out using global circulation model, that permitted eddies and sea ice, that they ran both with and without paramiterisation of polar lows. The high speed winds and heat fluxes that are observed in polar lows, as well as their integrated effects, are reproduced by the paramiterisation, which leads to simulated depth increases, and in the Nordic seas, frequency and area of deep convection, which then leads to an increased transport of heat to the north into the region, and deep water being transported southwards through the Denmark Strait. The authors1 conclude that for the large-scale circulation polar lows are important and suggest they should be included in climate short-term predictions. A decrease in the number of polar lows is predicted  over the northeast Atlantic in the 21st century by recent studies (Kolstad & Bracegirdle, 2008; Zahn & von Storch, 2010) and this would imply deep convection would be reduced and a potential weakening of the Atlantic meridional overturning circulation (AMOC).


Sources & Further reading

  1. Condron, Alan, and Ian A. Renfrew. "The Impact of Polar Mesoscale Storms on Northeast Atlantic Ocean Circulation." Nature Geosci 6, no. 1 (01//print 2013): 34-37.


Author: M. H. Monroe
Last updated 18/02/2013

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