The Arm

This melting season we witnessed something peculiar. Patches of highly concentrated ice - in the Beaufort and East Siberian Seas and on the other side in the Greenland Sea - started moving away from the ice pack in the Arctic Basin. We discussed this phenomenon at the start of August in the blog post Breaking Away From the Pack:

What if that forecasted high-pressure system over the Beaufort Sea starts to develop for real next week and the Beaufort Gyre kicks into gear again, spurred by westerly winds? One would think the small patch(es) in the Beaufort Sea would get pressed into the central pack again, but perhaps the bigger patch in the East Siberian Sea would get swirled loose by the winds blowing westwards. Either way it will be interesting to watch.

All of this more or less came about and since then we have witnessed the forming of holes in the central ice pack and massive movements of ice at the fringes of the ice pack. Not exactly breaking away from the pack, but as close as you can get to it.

Of course, Artful Dodger and Jack Taylor have been making animations that show all these things happening, but I decided to take a closer look at the arm of ice that is stretching out towards the Siberian coast. It has become of extra interest now that the extent has made a feint, fooling everyone into thinking the melting season was over. The recent decline is of course partly caused by compacting winds, but the arm is stretching so far southwards that melt has something to do with it as well (especially as sea surface temperatures are anomalously high in that part of the Arctic).

Have a look:

  

So, will it melt out completely? It's very hard to tell, but if it does extent might actually drop a bit more.

Here's an SST map for September from EORC/JAXA:

And here's an animation of daily sea surface temperature images from NCEP's Marine Modeling and Analysis Branch of the Environmental Modeling Center of the last 10 days:

Comments

[Artful Dodger]

Neven, there was some decent MODIS coverage of this area on Sep 17. Here's a link to the 1km-pixel image, in false colour: (red is sea ice, white is cloud)

http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r05c04.2010260.terra.367.1km

If you zoom in further to the 250m resolution, you can see the wisps of sea ice characteristic of a melting event. Also, HUGE potential for compaction here, long after the melt ceases.

[Neven]

Indeed, Lodger! I doubt it will drive total extent towards an even lower extent minimum, but it might slow the onset of extent and area increases. Area is currently rising very sharp, however. In part probably because all these holes in the spread out ice in and around Olga Strait still have to be filled.

[Peter Ellis]

Area is not clear cut. CT is rising, but IJIS is falling...

[Artful Dodger]

Peter: Agreed. The Healy is currently in the 'Beaufort finger' of sea ice. Tell me, do these look like melt ponds on the surface of the sea ice?

Healy show the air temp as 33.2 F ( 0.67 C ). The cruise report here shows SSTs between -0.9 and -1.2 C over the last 6 hours.

The local sea water melting point t(s) is about -1.6 C so we are probably seeing both bottom- and surface-melt. How's that for singing ?

[Steve Bloom]

A slightly later photo makes the melt ponds obvious. I interpret the appearance as basically slushy, cycling back and forth between freezing and melting.

[Artful Dodger]

An interesting story is continues to developing in the area of the E. Siberian "Arm". The Freezing line as shown by SSTs has continued to advance Northward since Sep 18 (the day of SIE minimum):