Polynyas – What they are and what they may mean for North America?

Polynyas are areas of persistent, almost permanent open water where in the past we would expect to find sea-ice flows.  For the most part, they tend to be roughly oval, oblong, or circular in shape, but they can be irregularly shaped, too.   The water remains open because of processes that prevent sea ice from forming or that quickly move sea ice out of the region.

Everywhere between the orange-yellow boundary in the median edge, 1981-2010 and actual sea-ice cover there is open water in our sea-ice concentration map for 23JUN19.  Except for the Barents-Kara (B-K) Sea region over Russia – where there has been no sea-ice – this is ALL NEW-FORMED POLYNYAS.

Screen Shot 2019-06-24 at 9.17.12 AMNote, the oblong open water shores of Arctic Alaska, Northwest Territories and Nunavut.  NSIDC and Fridtjof Nansen Environmental ResearchLaboratories

Screen Shot 2019-06-24 at 9.53.19 AMClose-up view of frost flowers grown on new ice in very calm conditions. Photo courtesy of Ted Maksym, United States Naval Academy. 

Sea ice is not a continuous, smooth sheet, but rather complex surfaces that varies dramatically across even short distances.

Sea-ice is usually covered with just plain snow, insulating it and delaying melting in the summer. The snow also modifies the electromagnetic radiation signal detected by polar satellites.  Wind from a consistent direction can blow snow into ridges parallel to the wind direction, just like small sand dunes. These complex, fragile shapes are called sastrugi.

Unusual features form on the surface of sea-ice may include  frost flowers – crystals of ice deposited when water vapor bypasses the liquid phase and becomes a solid. (Sublimation).  Frost flowers roughen the surface and dramatically alter its electromagnetic signal.

There are two types of polynyas (described below), differentiated by the mechanism of ice removal. One process often dominates in a given polynya, but both can occur…

Arctic Sea Ice Polynyas

Particularly with this oblong polynyas over Alaska, we are given something absolutely “new!” We have no idea how this will effect our Winter 2019-2020, nor that of the rest of the World until we model its appearance. Not an easy task.

To say something is “new!” in the Arctic is not a good thing, perhaps, during a rise in Global Temperatures to 1.5-2.0C above pre-Industrial levels.  We will monitor this new development.

It could be just a Bad Winter for the Eastern Seaboard, or it could be the ‘beginning of the end’ for the present Arctic Sea-Ice cover.  It is predicted by the IPCC reports and the National Arctic Report Card (USA) that the Arctic Polar Cap will melt completely within the next 10-15 years, then re-fomr with cooling temperatures.  Is this the beginning?  No one can tell, just yet.


 

 

 

 

 

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