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Thursday, January 10, 2013

"The impact of polar mesoscale storms on northeast Atlantic Ocean circulation," by Alan Condron & Ian A. Renfrew, Nature Geosci., 6 (2012); doi: 10.1038/ngeo1661

Nature Geoscience, 6 (published online December 16, 2012) 34-37; doi: 10.1038/ngeo1661

The impact of polar mesoscale storms on northeast Atlantic Ocean circulation

Atmospheric processes regulate the formation of deep water in the subpolar North Atlantic Ocean and hence influence the large-scale ocean circulation1. Every year thousands of mesoscale storms, termed polar lows, cross this climatically sensitive region of the ocean. These storms are often either too small or too short-lived to be captured in meteorological reanalyses or numerical models234. Here we present simulations with a global, eddy-permitting ocean/sea-ice circulation model, run with and without a parameterization of polar lows. The parameterization reproduces the high wind speeds and heat fluxes observed in polar lows as well as their integrated effects, and leads to increases in the simulated depth, frequency and area of deep convection in the Nordic seas, which in turn leads to a larger northward transport of heat into the region, and southward transport of deep water through Denmark Strait. We conclude that polar lows are important for the large-scale ocean circulation and should be accounted for in short-term climate predictions. Recent studies34 predict a decrease in the number of polar lows over the northeast Atlantic in the twenty-first century that would imply a reduction in deep convection and a potential weakening of the Atlantic meridional overturning circulation.


Anonymous said...

Not to talk against Prof I.Renfrew, but... as they decrease in the NE Atlantic, won't they go up in the N and E of Greenland/Spitzbergen, Perhaps once the Arctic is ice free on summers, they'll occur when there's major calving from the Greenland glaciers. No doubt this study is important wrt Great Britain winter weather and shipping in the North Sea. Just saying these kinds of local climate predictions may be confusing the issue of Arctic amplification. Of course in the issue of accuracy in local predictions these might well be important but couldn't these sorts of systems be incorporated in the synoptic scale lows tweaking them a bit when looking at the global scale. (Anyway, I'm probably over my head with this, some politicians want local near term predictions and this may well be the case here)

Tenney Naumer said...

Have a look:

Anonymous said...

yes the supplementary info @
explains better what they did. I think it's a bit similar to the models trying to get a good MJO.