Arctic Sea Ice

Concentration comparison

As ripping off graphs seems to be in vogue lately on the Arctic Sea Ice blog ;-), I've decided to copy an idea from commenter Kris. On his website he has pages with University of Bremen sea ice concentration maps of the past couple of years, enabling one to compare the different maps for a single date. I figured that would be a great addition to the Arctic Sea Ice graphs page, and spent most of this Sunday making it real: Concentration maps.

It looks something like this:

Which for me is a great and quick way to see how unusual something is, like the open waters in the western Kara Sea a couple of weeks back, or the retreat of the ice pack off Banks Island in the Beaufort Sea. It also makes it easier to compare years, in a way similar to the CT comparison page, minus the functionality. If you want to have a closer look I'd advise you to open the images in new tabs (by right-clicking them) which will get you a bigger version. Then switch between tabs, and count the amount of clicks when you scroll down with your scroll wheel to look at the region you're interested in.

So far I have only done May and June, 5 dates spread out over the month, as doing all the days in a month would be too much of a Herculean task for poor old, manual me. I will be uploading images for July and August when the time comes. I hope this is visible enough for everyone (I have a 20" monitor, and it works really well for me).

Novaya Zemlya April 2012

It's time to have another look at the region surrounding Novaya Zemlya, and see how the current situation compares to previous years, as the situation in the Kara and Barentsz Seas has been mightily intriguing this year. In the western Kara Sea, the basin between Novaya Zemlya and the Siberian coast, we saw a very early retreat, that except for last year has been unparalleled. Just like last year it froze over again when the winds turned, opened up again around the start of the month, and is yet again closing (see animation below), probably for the last time, with solar radiation coming into play now.

Here's the comparison with previous years, based as always on images from the Uni Bremen sea ice concentration map archive:

Things are looking much more 'normal' than they did over a month ago, except for the Barentsz Sea that seems to have reached an all-time low this year. As already mentioned the western Kara Sea has frozen up again. Not completely, but the difference with many other years is negligible. Another big difference is how the edge of the ice pack, under the influence of a persistent and large high pressure system over the central Arctic, has moved southwards in the past couple of weeks, enveloping both Svalbard and Franz Josef Land. That's quite a difference with the situation a little over a month ago, when both Svalbard and Novaya Zemlya looked circumnavigable on the LANCE-MODIS satellite images for a day or two:

2012 Novaya Zemlya Animation

I was planning to start making animations in May, but the sea ice has other plans. A little over a month ago I wrote a blog post about the spectacular and ominous situation in the Barentsz and Kara Seas. A combination of weather conditions and warm SSTs made the sea ice retreat so much that I ventured to say it looked unprecedented in the satellite record (without thoroughly checking, I admit). When the winds turned, the western Kara Sea, the part between Novaya Zemlya and the Siberian coast, finally froze over.

This situation has lasted about a week. The winds have turned again and sea ice is retreating so fast (see LANCE-MODIS satellite image on the top right) that I feel compelled to make an animation. But first let's look at images from the Uni Bremen sea ice concentration map archive to see what the situation in previous years was like:

Astute readers will have noticed that this is what the region looked like on April 15th, a little over a month from now.  There's a question mark for 2012, because as of yet we don't know how things will look by then. I'll fill in this blank in April.

Here's the animation for the last couple of days:

Barentsz and Kara

I had grown accustomed to writing Barentsz Sea without the Z, as everyone does. But I've decided to no longer scorn my Dutch roots. The Barentsz Sea has been named after Willem Barentszoon, a Dutch explorer and cartographer who died looking for an open Northeast Passage (now known as the Northern Sea Route) towards the end of the 16th century. At that time family names weren't used universally yet, and many people went through life with just a patronym, just like in Russian classic literature. Hence Willem was known as Barentsz., short for 'Barents zoon', the son of Barent.

The Barentsz Sea and its neighbour the Kara Sea are giving us an exciting prelude this year, as we await the melting season to start in about a month and a half from now. Large swathes of sea water that ought to be frozen by now, are still open or have opened up in the past fortnight.

According to the Norwegian Meteorological Institute this is what an average January (1976-2006) looked like in the region:

And this is how it looks now, one week into February:

September 2011 sea ice extent, looking back

Daily changes in the graphs, maps and numbers assessing sea ice are entertaining to follow. The day-to-day discrepancies between output from different research teams get close scrutiny by those of us on the outside, trying to learn more about what’s happening to the ice. Seen from the step-back view of monthly averages, however, daily disagreements blur into substantial agreement. Figure 4 illustrates by plotting time series of September means for five main indices produced by the National Snow and Ice Data Center (NSIDC: website, data), the University of Bremen’s Institute of Environmental Physics (Uni Bremen: website, technical paper), IARC-JAXA Information Systems (IJIS: website, data) and the Polar Research Group at the University of Illinois (Cryosphere Today: website, data). So far as I know, Figure 4 is the first graphic to show these five September series together. Disagreements among the indexes appear minor; all five vary together around declining area or extent trends that steepen over the period of observation.

 
Figure 4

SIE 2011 update 21: post mortem

During the melting season I'm regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2005-2010. NSIDC has a good explanation of what sea ice extent is in their FAQ. I also look at other things like sea ice area, concentration, volume, temperature and weather forecasts, anything that can be of particular interest. Check out the Arctic sea ice graphs webpage for daily updated graphs, maps and live webcam images.

September 24th 2011

This is the last SIE update for this melting season, which ended about two weeks ago (feels like an eternity). I have basically said everything I think needed saying with regards to the minimum, so I won't repeat myself here. Just like last year I've had a very educative experience, and I'd like to thank the 'old' crew and newcomers for all the info and inspiring speculation they've been bringing to this little corner of the Internet. That's what's making this blog worthwhile in my opinion.

As always I'll start with the IJIS sea ice extent graph:

We can see the upswing when the melting season ended abruptly on September 9th. After a few days the increase slowed down and it's now more or less tracking 2008. The interesting thing to do is to try and find out what the mechanism is behind the uptick and the subsequent slowdown in increase.

It has obviously everything to do with the weather at this stage of the transition phase between melting/compacting and spreading/freezing, so I suggest we first have a look at this animation of images from the DMI Centre for Ocean and Ice that I've saved:

Final score: 2011 vs 2007

Now that I've called the minimum, it's time to have a look at the differences between the two years with the lowest minimums in all data sets. This post will be a potpourri of different factors.

If we look at the six most important data sets - which IMHO are IJIS extent, NSIDC extent, Cryosphere Today area, Uni Bremen extent, DMI extent and PIOMAS volume - we see that this year a new record has been reached in three of them:

In the remaining three (NSIDC, IJIS and DMI extent) 2007 still holds the record low, but 2011 brushes past very closely and is firmly in second place:

If we compare the sea ice concentration maps from the University of Bremen we can see how close 2007 and 2011 match, despite differences in final shape:

Some more flash melting?

Update September 6th 2011: Some of the ice that was gone in the preliminary map for September 5th returned in the final version. Below to the right there's a new animation that shows maps for the 4th, the preliminary and the 5th.

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Today's preliminary sea ice concentration map from the University of Bremen holds yet another surprise. A large area of low concentration ice has suddenly disappeared in what I refer to as the Laptev Bite, the place where warm waters from the Laptev Sea have been munching their way into the ice pack.

Of course, just as last time, this doesn't mean the ice has totally disappeared. It just doesn't show up on the image because the concentration has gone below the threshold, for whatever reason. And mind you, this is a preliminary map. The definite version might still show a different picture.

Nevertheless, that's quite a bite!

I'm not sure what the reason could be. This time there was only a smallish cyclone passing by, not like that big one from the last flash melting event.

But maybe that was enough to stir the thin ice up.

Let's wait and see what happens next.

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Update:

Here's an ENVISAT radar image of this area for September 5th from Arctic.io:

2011 End Zone

Last year I wrote a series of five posts called End Zone, comparing different aspects of the final phase of the Arctic melting season in different years, to be able to predict a bit what those last weeks of the 2010 melting season could be holding in store. A lot of that ground work still stands, so I don't have to repeat it this year. In this post I'll be looking at sea ice concentration and sea surface temperatures mainly, as these are most interesting right now. I basically said everything there is to say about atmospheric pressure, air temperature and ice displacement (no more PIPS, sniff) last year.

Sea ice concentration

I'm trying out something new here, which I hope you'll like. I'm comparing the years of the new Arctic era with 2011 on August 29th by fading the images:

2011 looks quite a bit like 2007, except that the large protuberance is sticking out in the East Siberian Sea instead of the Laptev Sea. That protuberance blocked the Northern Sea Route right till the end of the 2007 melting season. This year it's been wide open since very early on.

Flash melting

I introduced the term 'flash melting' in a recent SIE update. It was a pun on the term 'flash flooding' where lots of rain falls out of the sky in a short amount of time, causing creeks and rivers to flood very fast. I based the concept on the state of large parts of the ice pack in the Beaufort, Chukchi and East Siberian Seas that looks like slush puppie on the satellite images. It seems so weak that one can't help but wonder if it will all "just melt away quite suddenly", to quote Professor Peter Wadhams from this 2007 BBC interview (as I did in the piece CAPIE hits record low).

In the last two days something weird has happened on the sea ice concentration maps of the University of Bremen, with large swathes of ice suddenly disappearing from the radar (the full animation from August 6th-22nd can be watched here) on the upper left of the image:

Update August 24th: Added yesterday's image. Could be the sensor is picking up ice again.

Update August 25th: Added yesterday's image. No more flash melting (thank God).

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This looks so spectacular that it could just be a fluke, a deceived satellite sensor. Flash melting is a nice term for fast melting, but it can never be as fast as flash flooding. It ought to occur more on a time scale of say one week (which is very fast in the Arctic). Because however weak the slush puppie ice may be, it still takes large amounts of energy to make it disappear completely.

On the other hand IJIS extent took a bit of a nosedive with a reported melt of 98K square km for yesterday's date, and there's a huge cyclone battering the ice as we speak: