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As promised in my previous post on the situation in the Bering Strait and Sea, here's an updated comparison with previous years around this date (images from the Uni Bremen archive):
2011 seems to be ahead of 2004 and 2005, if only slightly (mainly because there's less ice in the Gulf of Anadyr). This year still ressembles 2007 most. But the melting is almost done in the Bering Sea, so from now on we'll concentrate more on the Chukchi and Beaufort Seas:
This is a follow-up to the first installment on the breaking up of the landfast ice on the shores of Barrow, Alaska.
Each year a few kilometres of fast ice gets stuck to the coast off of Barrow. The Sea Ice Group of the Geophysical Institute at the University of Alaska Fairbanks tries to predict when this fast ice will start to break up. In typical years, the timing of break-up is associated with the amount of incoming solar energy, and so they use solar flux data to determine when the fast ice will start to break up and the coast is cleared. This graph from the 2010 Sea Ice Break-Up Forecast webpage shows the relationship between solar flux and break-up in previous years:
One important factor for the forecast is the formation of grounded pressure ridges. These ridges are formed when the ice converges towards the coast, gets pushed together, ice floes flip and get stuck in the sea floor of the shallow waters off the coast of Alaska:
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 graph webpage for daily updated graphs, maps and live webcam images.
May 25th 2011
There's still some time to go before we reach the end of the melting season and see where this year's minimum extent ends up in the list. In the meantime we have to satisfy ourselves with some other, minor milestones. Werther came up with a good one: Will this year's IJIS SIE trend line dive below the 11 million mark before the end of the month? If it does, it would be for the first time in the IJIS dataset.
To be fair, I was expecting the SIE number to decrease faster than it did, based on the setting up of the Beaufort Gyre. This is one of the things that made 2007 such a big sea ice loss year. For weeks on end the Beaufort Gyre kept turning in a clockwise fashion and churned the sea ice as well as transported it to the North Atlantic (with the help of the Transpolar Drift Stream) where it melted out.
It was naive of me to think that this would immediately lead to bigger daily SIE decreases. These things always need a bit of time, until the shift in conditions is done. In this case the cold air cleared from the Canadian side, winds started to blow the ice pack away from the Canadian and Alaskan coast, and a semi-static high pressure area was bringing clear skies for the eternal sun to shine in.
But this also meant, of course, that things slowed down on the Siberian side, which up till now had been the place where all the action was. And so SIE decrease slowed down a bit as well right after the last SIE update, but just for a couple of days and just below the monthly average, which means the curve is still smoothly going down.
In fact things have speeded up a bit in the past few days. If this keeps up the 11 million mark should be in sight by the end of the month.
Sea ice extent (SIE)
Here's the IJIS SIE graph:
The current difference between 2011 and the other years is as follows:
This is a quick and dirty blog post to be used as a reference later on. Yesterday I remarked in the comment section of the last SIE update that I saw some melt puddles starting to form on the ice that can be seen on the webcam in Barrow, Alaska (see map to the right where that is). Each year a few kilometres of fast ice gets stuck to the coast. The Sea Ice Group of the Geophysical Institute at the University of Alaska Fairbanks tries to predict when this fast ice will start to break up.
They have a great website and I can highly recommend reading their forecast page for last year that has a lot of info on what it is they do exactly. They also have a webpage that is filled to the brim with graphs that are monitoring all kinds of current conditions (temperature, thickness, relative humidity, etc). And last but not least, the thing that has inspired this blog post, they have a webcam in downtown Barrow that is updated every five minutes. Lodger offered a link to an archive of these images that I'll use for a next blog post that compares webcam images from 2008 to the present day.
Here's a good image that shows the first melt puddles:
This isn't the place where they are monitoring break-up conditions, by the way. They do this a bit further north at the Navy Arctic Research Laboratory (NARL):
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:
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 graph webpage for daily updated graphs, maps and live webcam images.
May 15th 2011
First, let me apologize for not doing an update last week, even though I promised I would do one every week from now on. There's only so much time, and the pieces on sea ice thickness took precedence. And although as fascinating as always, nothing really spectacular has been happening with the Arctic sea ice in the past few weeks. But this depends on your perspective of course, as there's always more to the eye in the Arctic.
What could be labeled as a lack of spectacle is the fact that the sea ice extent decrease has been incredibly steady. Except for a very short blip upwards when an extent increase of 26,094 square km was reported for May 6th, the trend line for 2011 is dropping very gradually (as can be seen on the IJIS graph below). The curve has been remarkably steady all year.
However, and this in a way is quite spectacular, the actual circumstances on the ground haven't been steady at all. The Arctic Oscillation turned negative at the start of the month and as we saw in the previous SIE update this meant that the anomalously warm air in Siberia was moving slowly towards North America. But instead of getting more negative the AO index has remained stuck just below neutral.
High and low pressure areas are continuously trading places, resulting in ice displacement arrows pointing every which way from one day to the next. One other effect is that in the past week temperatures have shown a negative anomaly practically all over the Arctic (more on that below). Moreover, our CAPIE index has dipped several percentage points below other years, which could be a sign that there is a slight divergence of ice (more on that below as well).
Both these factors, especially combined, ought to have slowed down the rate of extent decrease. But extent is plodding downwards unperturbed, and showing a very decent average daily decrease for the month so far. So the fact that extent decrease isn't spectacular, is pretty spectacular, si vous catchez mon drift.
Sea ice extent (SIE)
Here's the IJIS SIE graph with its smooth curve for 2011. It has just passed the 12 million mark:
The current difference between 2011 and the other years is as follows:
Between brackets is the average daily extent rate for the month of May. 2011's average daily extent rate for May is -51,049 square km, which is quite a bit more than most other years, very close to 2009, but of course out of 2010's league. 2010 has been catching up very fast - the difference with this year was 474K two weeks ago - and is now in 5th spot. It will take the lead quite soon and hold it until the end of June, with the incredible streak we witnessed last year. 2011 is currently in third position, more or less tied with 2007.
The slowly, but steadily increasing rate of decrease for this year is also reflected in this graph from the university of Bremen that shows the change per month of Arctic SIE:
If things continue in this manner, 2011 will soon have the fastest rate of SIE decrease after 2010.
While trying to find out why the TOPAZ forecast maps were no longer updated I came into contact with Dr Laurent Bertino, a research director at the Nansen Environmental and Remote Sensing Center who is responsible for the TOPAZ system that is delivered as part of the MyOcean project.
Not only did he direct me to the new dynamic viewer that contains the images of sea ice thickness (and much more), but he also consented in my request for a short interview.
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N: Laurent Bertino, thanks for this interview. What is it you do exactly over at the Nansen Environmental and Remote Sensing Center?
LB: The Nansen Center is a private research foundation (~60 persons) with various activities in climate research, remote sensing, modeling and data assimilation, the latter two are the activities I am personally involved in. See our fresh new web-site for more information: http://www.nersc.no/
What we call "data assimilation" is working out the combination of numerical model forecast and observations that makes a forecast most accurate. This is a field at the crossroads of mathematics, statistics, physics and computer sciences.
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N: There are several discrepancies between the sea ice thickness models. I discussed them in a recent blog post and follow-up. PIPS 2.0 for instance is showing a lot more thick ice than TOPAZ. What are your thoughts on this?
Unfortunately I couldn't include PIOMAS in the last blog post I did on sea ice thickness models, but to make up I'm putting up the latest volume data from the PIOMAS model, as calculated by FrankD.The graph was updated a few days back and the anomaly trend line seems to have dipped below 2 STD again.
As was discussed in the comments following Larry Hamilton's excellent Trends in Arctic Sea Ice Volume, these numbers differ slightly from the official PIOMAS numbers, because the latter are obtained by running several ensembles, whereas the PIOMAS graph (on which FrankD bases his dataset) on the website of the University of Washington's Polar Science Center is based on the results from the ensemble that has the best overall performance.
FrankD has also sent me this graph with simple quadratic trend lines for each month (click for a larger version):
As promised I'm returning to the sea ice thickness models I wrote about two weeks ago, highlighting some of the current differences between PIPS, PIOMAS and TOPAZ. The satellite that will give us a definitive answer on ice thickness and volume, CryoSat-2, is currently being calibrated with the help of surveys by ESA and NASA. It will take some more time before definite data will be made publicly available, so in the meantime we'll continue looking at what sea ice thickness models have told us so far.
PIPS 2.0 2004-2011
PIPS 2.0 (Polar Ice Prediction System) has an excellent archive, so I have retrieved all the ice thickness images from the period 2004-2011 and put them side by side (click for a larger image):
Towards the end of last melting season we had a lot of fun speculating about large patches of ice getting separated from the main pack. Well, at least I did. So much so that I wrote an article about it, called Breaking away from the pack. Much of the ice seemed to be very thin at the time and there was so much divergence that a bit of consistent freak weather ought to have been enough to blow away a patch. It didn't come about in the end, but was educative nonetheless.
I was reminded of this as we witnessed two things in the past few weeks. The first was that the ice south of the narrow Bering Strait seemed to get cut off from the ice in the Chukchi Sea. The other was a huge polynya forming north of Franz Josef Land (a group of islands more or less halfway between Svalbard and Severnaya Zemlya) that seems to extend towards Svalbard, cutting off all the ice south of it. A very important factor in this is the upwelling of warm water from the West Spitsbergen Current.
The large patches of blue water can easily be discerned through the clouds on yesterday's MODIS satellite image:
To prevent my becoming a prisoner of premature spouting of speculations I decided to have a look at previous years, using the University of Bremen's excellent archive of sea ice concentration maps. Let's see how peculiar these dark blue holes really are:
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