Arctic Sea Ice

2011/2012 Winter Analysis

I'm starting this blog post off with a conclusion that was reached a while back already: sea ice on the Atlantic side of the Arctic looks vulnerable, sea ice on the Pacific side should be thicker.

Right, with that out of the way we can now look at various aspects of the 2011/2012 freezing season, and compare them to previous years, to be precise the previous freezing season of 2010/2011, and the freezing seasons leading up to and following that other record year: 2006/2007 and 2007/2008. Simply put: I'll be comparing 2007, 2008, 2011 and 2012 before their respective start of the melting season.

I'll try not to use too many words, but I'll be using a lot of images. Click on them images if you want a bigger version.

Ice age

I'll start with the AARI ice age maps. These images are for the end of April, and they look upside down, because it's from the perspective of the Russians who produced them:

Another source of info on MYI

Just when you thought you knew it all, someone shows up with something new. That someone is Bob Wallace commenting in the latest post on CT SIA long-term regional graphs. And that something is this website showing the age of Arctic sea ice: Arctic Ice Age.

This website has animations for each month of the past 28 years, based on data provided by James Maslanik and Chuck Fowler, which are also used for the NSIDC March and September analyses of ice age distribution. It's a great tool to compare ice age distributions from year to year, and it even has an animation showing the weekly development of the 'ice year' since the start of the freezing season up to present. The only minor quibble is that this animation is still showing the freezing season starting in 2010.

But I'm definitely not complaining. Just like the CT SIA long-term regional graphs, this is the kind of info that makes it visually crystal clear to even the layest of lay persons what is going on in the Arctic. Thank you for putting this out there.

NSIDC Arctic sea ice news April 2012

Interesting bits from the NSIDC monthly analysis:

Arctic sea ice enters the spring melt season

Arctic sea ice reached its annual maximum extent on March 18, after reaching an initial peak early in the month and declining briefly. Ice extent for the month as a whole was higher than in recent years, but still below average.

As the melt season begins, researchers look at a variety of factors that may contribute to summer ice melt. While the maximum extent occurred slightly later than average, the new ice growth is very thin and likely to melt quickly. Ice age data indicate that despite the higher extent compared to recent years, the winter sea ice continues to be dominated by younger and thinner sea ice.

A first clue

However unpredictable it is, we still like to gather as much information as we can about the coming melting season. Obviously it's important to get an idea of what happened to the Arctic sea ice during the last freezing season. We've just witnessed the spectacular retreat of ice and late freezing in the Barentsz and Kara Seas and know that the Arctic Oscillation was mostly positive this winter, which ought to have caused increased export of sea ice through Fram Strait.

This has now been confirmed through a new NASA study by Josefino Comiso (published in the Journal of Climate):

still image captured by Arcticicelost80 from the video in the NASA news release

The NASA study shows much more, of course, about the long-term decline in MYI, but to be honest I'm primarily interested in what it can tell us about the coming melting season, as everyone here knows about long-term declines. The graph above shows the amount of multi-year ice (MYI) on January 31st since 1980. This year's MYI cover on that date is just a tad higher than that of 2008, which was extremely low due to the preceding record melting season of 2007. I'm expecting James Maslanik's yearly ice age percentage graph to come out soon (probably the next NSIDC monthly summary) and Arctic.io has promised to make a video of ASCAT radar images of the Arctic sea ice pack during winter (like he did last year). That will give us a more detailed look with regards to MYI.

New paper from Maslanik et al.

I'm going to try and regularly report on new scientific papers that discuss some aspect or other of Arctic sea ice. Creating a special segment on the blog that categorizes all important research papers (a bit like the AGW Observer blog) is still on my to-do list.

Following yesterday's blog post that referred to Chris R's blog where he devotes several posts to multiyear ice, I now call attention to a new paper by Maslanik, Stroeve, Fowler and Emery called Distribution and trends in Arctic sea ice age through spring 2011, which was published in Geophysical Research Letters on July 14th.

From the abstract:

Analysis of a satellite-derived record of sea ice age for 1980 through March 2011 shows continued net decrease in multiyear ice coverage in the Arctic Ocean, with particularly extensive loss of the oldest ice types. The fraction of total ice extent made up of multiyear sea ice in March decreased from about 75% in the mid 1980s to 45% in 2011, while the proportion of the oldest ice declined from 50% of the multiyear ice pack to 10%. These losses in the oldest ice now extend into the central Arctic Ocean and adjacent to the Canadian Archipelago; areas where the ice cover was relatively stable prior to 2007 and where long-term survival of sea ice through summer is considered to be most likely. Following record-minimum multiyear ice coverage in summer 2008, the total multiyear ice extent has increased to amounts consistent with the negative trend from 2001–2006, with an increasing proportion of older ice types. This implies some ability for the ice pack to recover from extreme conditions. This recovery has been weakest in the Beaufort Sea and Canada Basin though, with multiyear ice coverage decreasing by 83% from 2002 to 2009 in the Canada Basin, and with more multiyear ice extent now lost in the Pacific sector than elsewhere in the Arctic Ocean.

A good start

One of the commenters of this blog, Chris R, informed us in the comment section of SIE update 11 that he has started a blog and kicked it off with a couple of posts on Arctic sea ice (always a good start).

Most of us know this graph (from NSIDC monthly summaries, which I also used in this post on Ice thickness models) that Chris R uses at the start of The loss of multi-year sea ice, Part 1:

What is interesting is how Chris R compares Maslanik's graph with another graph from Nghiem et al's Rapid reduction of Arctic perennial sea ice (2007):

And follows it with the following question:

Both are startlingly different, yet apparently cover the same thing - the fate of the MY sea ice. So why is there a difference between Nghiem 2007 and James Maslanik's treatments of the loss of perennial sea-ice? And does this difference tell us anything of use?

There are various differences between the aproaches of Nghiem and Maslanik, also differences in the areas covered. However in my opinion the major difference is in the treatment of mixed ice.

I can recommend reading this blog post as well as the other ones he has produced so far:

The loss of multi-year se ice, Part 2

In flux

Ice Age

No,  this is not a review of one of the Disney sequels. Fredt34 sent me a mail to draw my attention to this ice analysis map from the Arctic and Antarctic Research Institute from St. Petersburg, Russia. This institute had some great weekly sea ice displacement forecast maps last year, but unfortunately the web page went down in the middle of the melting season.

This ice analysis map is nice too, though, as it gives us an idea of the age of different parts of the ice pack, which is why I think this blog post will fit in nicely with the recent string of posts on sea ice thickness.

Here's the current situation according to AARI (click for a larger version):

The light blue shows where the open sea is, and the dark blue is for water covered with Nilas (very thin ice). The pink is for young ice between 0-30 cm thick, and the green is first-year ice with a thickness of 30-200 cm. The brown colour for olde ice that survived at least one melting season, is what interests us most, as all the other colours will probably melt out this season.

To us Europeans and Americans this image might look like it's upside down, but that's because it's from a Russian perspective. They are perfectly entitled to do this. In fact, I'll even flip this Arctic sea ice age figure from the NSIDC March analysis (courtesy of J. Maslanik and C. Fowler from the University of Colorado) so it's easier to compare:

Ice In Baffin Bay

It looks like the ice floes in Baffin Bay didn't compact too well during the winter.  Instead of slabbing and compacting, the floes appear to have merely become congealed together with winter ice.  That ice is now first year ice.  'First year' doesn't imply year-old: the ice which surrounds older floes in Baffin Bay is just over 6 months old.

As ice forms over sea water it traps pockets of water.  Over a period of time the ice in effect squeezes the salt water out through the bottom.  This makes older ice less salty.  Salty ice is a matrix of ice crystals surrounding pockets of water.  That structure makes the ice somewhat flexible and weak: the younger the weaker.  Salty ice also melts faster than fresh-water ice.

Recent images from the Arctic mosaic show cracks in the newer ice running outside of the older ice.  This appears to me to be yet one more positive feedback in the ice-melting saga.  Previously the ice in Baffin Bay has built up in thickness by slabbing.  It takes much more energy to crack thick multi-year ice than to crack the first year ice that surrounds last year's floes.

The images below, all taken from Arctic mosaics, compare ice on March 22 2009, 2010 and 2011.

March 22 2009

 

March 22 2010

 

March 22 2011

 

March 22 2011 in more detail

 

My expectation is that this ice will break up, disperse and melt rapidly as the melt season gets fully under way.  Baffin Bay ice usually presents a great obstruction to the export of ice from Nares Strait and the Canadian Archipelago.  I suggest that it will not continue to do so for long.

 

Images courtesy http://rapidfire.sci.gsfc.nasa.gov/

Race to Fram Strait 6

Now that the melting season is really over (wait, let me check that... Yep, it's finito) I'm giving Artful Lodger's animations of cropped IJIS images of both sides of the Arctic one last minute in the limelight. There's still plenty to see there, especially The Arm of course. Will it disappear or will the freeze-up give it new flesh and bones?

 

Fram and the Frozen Holes:

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: