People sometimes say that watching the Arctic sea ice melt is like watching paint dry. Well, let me ask them this: does their freshly painted wall have a NASA satellite monitoring it? Because if they do, I'm coming over with a beer and a bag of salted pistachios.
Yes, we're finally there. The MODIS white ball has been growing smaller and smaller and will be gone in a couple of days. And this means the gazing for things out of the ordinary is resuming. Of course, speculation has already started here and there, as the fringes of the ice pack have been visible for quite a while. I had a look at the situation in the Bering Strait, and Patrick Lockerby's first guest post here focused on the ice in Baffin Bay. Over on Patrick's blog, in the comment section of Arctic Ice March 2001 Update #2, we already had a bit of a look at Nares Strait, which is one of the most interesting things to keep an eye on in the Arctic, especially around this time.
So to celebrate the return of the full Arctic Mosaic I'll give a brief overview of the current situation in the Nares Strait:
As Patrick pointed out in his second March Update an ice bridge has formed in Nares Strait blocking the export of ice from the Lincoln Sea. This ice bridge doesn't always form which has repercussions for the transport of ice from the Lincoln Sea to Baffin Bay.
In the last couple of years the ice bridge didn't form. 2007, 2009 and 2010 all had a more or less open Nares Strait at the end of the winter season (2008 was an exception, when an ice bridge formed, albeit further north than normal) in the sense that ice floes were transported through the strait. Here's an overview of the area in the period 2003-2010 around the end of March:
2009 and 2010 were retrieved from the Arctic Mosaic, previous years from the MODIS Rapid Response System Real-Time archive. The quality of the images isn't all that great, because I was too lazy to do it properly (one time only, I promise), but you get the gist.
This year an ice bridge has reformed. Although the winter of 2010 started out anomalously warm, this region between the Canadian Archipelago and Greenland saw some very low temperatures since the beginning of 2011, freezing up the waters of Nares Strait. Here's yesterday's MODIS image (March 29th):
Although the ice bridge seems pretty solid on MODIS images, we can see on these radar images from ESA's ENVISAT satellite (source: DMI) that the bridge consists of ice floes trapped in the Strait and kept there by water that has frozen up. The parts of frozen water look much darker however, and if I'm not mistaken, darker means less thick.
Here's the southern part of the strait (more geographical details on Wikipedia):
And the northern part of Nares Strait, with the Petermann Glacier visible:
North Water Polynya
One other thing that had me wondering over at Patrick's was the fact that there were so many ice floes right behind the ice bridge in the northeastern part of Baffin Bay, the area that is known as the North Water Polynya, a large patch of open water. This polynya used to be a common feature of this part of the Arctic and important for local ecosystems, but now that the ice bridge doesn't always form the water is less open than it used to be (also leading to articifically higher area/extent numbers BTW). Here's an interesting paper on ocean circulation within the North Water Polynya. And here's an image from Patrick's blog that shows how this polynya looked in May 2006.
The fact that there was hardly any open water a week ago (see the image on Patrick's recent Arctic analysis for March) suggested that the current through Nares Strait was flowing northwards - instead of the other way around, which I believe is more common - pushing the ice floes in Baffin Bay to the edge of the ice bridge. This was corroborated by one of the buoys from the International Arctic Buoy Programme drifting away from the north end of Nares Strait (see image on the right).
In fact, there was a polynya forming in the Lincoln Sea just 4 days ago:
But things can change fast in the Arctic. In the meantime the ice floes in Baffin Bay have moved back from the edge of the ice bridge - as can be seen on one of the images above that shows the situation for March 29th 2011 - and there is a considerable area of open water that starts to shape into a North Water Polynya. The temporary polynya in the Lincoln Sea has been covered in thin ice and part of the ice pack has fragmented and is pushing towards the Nares Strait, which could be a sign that the current has reversed again:
So now the big question is how long the ice bridge will hold. Will it be long enough for the North Water Polynya to form? Or will it break up giving the ice floes from the ice pack in the Central Basin free passage towards Baffin Bay? Patrick has repeatedly stated he expects the ice bridge to break up soon, with ice from Lincoln Sea advecting through Nares Strait by April 14th. I tend to agree with him.We'll be following developments in Nares Strait closely the coming weeks.
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As always, I refer to Patrick's classic Broken Bridges of Nares for a more in-depth look at the situation last year and the Nares Strait in general. A large part of another article of his, Arctic Ice 2010 #3 - The State of the Ice, is about Nares as well. Some more info written last year can be found on the website of Environment Canada. Finally, here's the first animation of Nares Strait I made last year.
Nice summary, Neven--thanks. Thanks, too, for an opening paragraph that featured a real LOL.
Posted by: Kevin McKinney | March 30, 2011 at 15:31
I second that LOL!
If I say that this is a great article does that make us a mutual appreciation society? Oh, to hell with it! Great article!
Following a suggestion by The Yooper, I reposted my March #2 update over at Skeptical Science, with a brief introduction and some minor updates.
http://www.skepticalscience.com/Chatter_box_March_26_2011.html
Currently in progress is a Chatter-Box article on how materials science can help us understand ice advection processes in Fram Strait. The title is "Fram Jam Floe Flows". :)
Posted by: logicman | March 30, 2011 at 16:43
"The title is "Fram Jam Floe Flows". :)"
Not writing for radio, luckily!
Posted by: Kevin McKinney | March 30, 2011 at 19:14
Glad you LOLed, gentlemen. :-)
Looking forward to your Flam Joe... Fram Flam Jows.. Jam Floes...
...to your article, Patrick!
Posted by: Neven | March 30, 2011 at 19:19
Slightly OT. The bit of the Peterman Glacier, that broke off last year and had the beacon on it, has left the arctic circle http://www.sailwx.info/shiptrack/shipposition.phtml?call=47557 . Is this Lockerby Island? I haven't looked for it on MODIS yet.
Posted by: MikeAinOz | March 31, 2011 at 00:15
Patrick has some images of a first small break-up at the southern end of the Nares Strait ice bridge.
Posted by: Neven | April 02, 2011 at 09:31
Neven: I just posted some more images of the breakup in an article:
http://www.science20.com/chatter_box/nares_ice_bridge_breakup-77741
My short term forecast of March 26 is looking good:
"The Nares ice bridge will be fragmented, and the ice in Kane Basin will be melting out by April 7th." Was I being too cautious with the plus/minus 3 days? Time will tell.
Posted by: logicman | April 02, 2011 at 16:28