Arctic Sea Ice

Arctic storm part 3: detachment

Yes, ladies and gentlemen, the Arctic summer storm is still there. After approximately 48 hours (which is long for an Arctic summer storm) it has weakened some compared to yesterday or the day before, but as far as I can see sea level pressure in the centre of the storm is still around 970 mb, which is low.

And so we're still seeing significant changes on the Uni Bremen sea ice concentration maps. Here's the animation from August 3rd to 7th:

That large patch of sea ice in the East Siberian Sea is almost entirely detached from the main ice pack. This is something I for one have never seen before, and I wouldn't be surprised if it's unprecedented in the satellite era. We have speculated a lot about this in previous melting seasons, but now the moment seems to have finally arrived. The fact that the ice pack can get divided like this, is yet another sign that the ice is exceptionally thin, as thin ice gets pushed around more easily and melts quicker, leaving open space between thicker, slower moving ice floes.

I've also updated the animation of DMI sea level pressure maps that shows the development and position of the storm:

Arctic storm part 2: the color purple

A new day with new information. Here's an animation of Uni Bremen sea ice concentration maps from August 3rd-6th:

We see some more flash melting from the 5th to the 6th on the edge of the ice pack in the Beaufort Sea region, although technically I think this is more compaction than real melting. We also see some of the early flash melting flashing back, or 'unflashing', in the East Siberian Sea. It looks like that large swath of ice there has almost detached itself from the main ice pack.

On this animation of DMI sea level pressure maps we can see how the cyclone developed from the 3rd to the 6th. The purple in the centre of the storm shows how low sea level pressure was and still is (lowest I've seen in yesterday's reports was 963 mb):

Arctic storm part 1: in progress

This is what I meant when I said 'flash melting' yesterday:

Now it's there on the Uni Bremen sea ice concentration map, the next day, poof, it's gone. Mind you, not all of it is gone, the sensor is thrown off a bit due to that crazy cyclone downstairs, but it ain't exactly good for the ice if you catch my drift.

Here's the culprit:

Cyclone warning!

I have postponed this post until I was sure that what follows is going to happen.

Remember the term 'flash melting'? That's when from one day to the next large swathes of ice disappear on the University of Bremen sea ice concentration maps. We witnessed one such instance last year when a relatively large and intense low-pressure area moved in from Alaska over the ice in the Beaufort and Chukchi Sea regions (see blog post). It lasted about a day or two and then quickly faded, but the effects were spectacular.

Well, it looks like we have something bigger coming up this year. This is the ECMWF weather forecast for the coming four days (click for a bigger version):

Not only does this low-pressure area, or cyclone, look bigger, more intense and longer-lasting than the one from last year, the ice also seems to be in a weaker state than ever, as evidenced by the fact that 2012 trend lines on both sea ice area and sea ice extent graphs track lower than previous record years, despite weather that until recently would completely stall the decline.

There are many things that cyclones do to cause flash melting:

New CAPIE record

The trend line on one of our in-house charts has broken last year's record:

56.85% vs 57.39% on August 12th 2011.

CAPIE stands for Cryosphere-today Area Per IJIS Extent, and it tells us something about the compactness (official scientific term) of the ice. It all revolves around the different definitions for sea ice area and sea ice extent, which are two ways of calculating the total ice cover. The NSIDC explains it well:

PIOMAS August 2012

The PIOMAS people are early this month with updating the numbers (probably so that the SEARCH people have some extra info for their SIO). Here is the updated Arctic sea ice volume graph as calculated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center:

I think it's pretty safe to say that we're going to have a new record volume low, although the difference with 2010 and 2011 has become smaller. Right now it's 1249 and 730 km3 respectively.

Here is Wipneus' version with the calculated "expected" 2012 values (dotted lines), based on the same date values of 1979-2011 and an exponential trend.
A caveat from Wipneus: "Note that the statistical error bars are quite large."

Peeking through the clouds 2: animation

This a follow-up to last week's blog post with the same title, in which I discussed the MODIS Composites that are made every week by Environment Canada. Their False-Colour Composite image which can be downloaded here is particularly interesting because it allows us to see through the clouds. This is useful, because low-pressure systems have been dominating the Arctic in the past weeks, and that means that clouds hide the situation below.

Now right after I posted this blog post commenter dabize sent me alternative versions of these composite images, in which he had removed the clouds even more. This image that he sent me yesterday clearly shows the ice loss (red) since June 5th up till now:

But even more visually stunning are the blue images he sent me that I have turned into an animation (each frame represents a week of averaged LANCE-MODIS satellite images):

2012 lower than all minimums before 2007

With more than a month left to go before the melting season ends, 2012 has already surpassed all of the sea ice area minimums preceding 2007 in the Cryosphere Today (Polar Research Group, University of Illinois at Urbana-Champaign) data set. Larry Hamilton's bar graph makes for an excellent visual representation of this fact:

Needless to say, this is the earliest date for this to happen, as 2012 is still in the lead in this data set. Jim Pettit has more statistical info: