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 2006-2009. The IJIS graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a good explanation of what sea ice extent is in their FAQ.
August 14th 2010
There has been an unusual amount of days between this SIE update and the last one, not because the melting season is over and the Arctic has recovered and the alarmist fun of proclaiming the end is nigh has been denied me, as everything is still very much open. The ice can still dip below 5 million square km, or - if the weather doesn't cooperate - stay above it.
No, the reason I was off-line for so long, was that I decided to take a few days off because a good friend from the Netherlands was coming over. He had taken some of those herbs from Amsterdam along with him, which explains part of the title. I was contemplating doing some science in the spirit of Carl Sagan, but thought better of it. Instead I watched the movie Contact yesterday, which was written by Sagan. And very good and thought-provoking it was.
So what has happened in the past week in the Arctic? Well, for one, that forecasted high has developed and shifted over to the Canadian Archipelago. It looks like this has brought an end to the spreading out of the ice, with winds blowing in a clockwise fashion and away from the coast. It hasn't brought any serious melting figures as of yet, but the daily reported extent numbers show a relatively stable decrease of around 60K square km per day (which explains the other part of the title).
These are the consecutive daily melts as they were reported by IJIS: 50,313 square km for the 8th, 68,125 square km for the 9th, 60,781 square km for the 10th, 67,969 square km for the 11th, 61,719 square km for the 12th, and today's revised number was 59,531 square km. Except for the 8th of August, all of these melts were second highest for those dates in the period 2006-2010.
What this means is that 2010 is still in second place. It has managed to extend its lead over 2008, 2009 and 2006 since the last SIE update and even nibbled a bit at that tremendous lead 2007 has built up so far. As is known 2008 maintains a pretty hefty rhythm in this period, so it will be interesting to see if 2010 can keep up.
The current difference between 2010 and the other years is as follows:
- 2006: -373K (37,697)
- 2007: +705K (57,041)
- 2008: -138K (70,333)
- 2009: -235K (48,654)
The average daily melt for the month of August is between brackets. 2010's average daily melt for August is currently 67,031 square km per day.
If 2010 loses as much sea ice extent as...
- 2006 did after this date it will bottom out at 5.41 million square km.
- 2007 did after this date it will bottom out at 4.96 million square km.
- 2008 did after this date it will bottom out at 4.58 million square km.
- 2009 did after this date it will bottom out at 5.01 million square km.
Here's the IJIS sea ice extent graph:
Strangely enough sea ice area has been decreasing at a very slow rate. The trend on the Cryosphere Today sea ice area anomaly graph was holding steady at around 1.5 million square km below the 1979-2008 mean, but has now plummeted back to -1.277 million square km. The sea ice area in the Arctic Basin and the East Siberian Sea has stopped dropping for a while now and has even been going up in the past few days. The same goes for the Laptev Sea and the Canadian Archipelago where multi-year ice from the Arctic Basin has been spilling into its straits and channels. The Kara Sea and the Beaufort Sea seem to have reached their bottom.
If we look at the compactness graphs that show the ratio between CT sea ice area and IJIS sea extent (a not so trustworthy, but still interesting indicator of melt ponds and divergence/convergence that lets us compare 2010 to previous years), we see that the slowdown in sea ice area decrease has caused compactness to go up. It was holding steady around 65%, but has gone up in the last day and currently stands at 67.62%.
It remains to be seen whether 2010 will reach a new bottom this month, like 2007 and 2008 did. Have a look at FrankD's latest compactness graph that shows the ratio between IJIS extent data and IJIS area data estimated from the IJIS sea ice area graph and looks quite a bit different.
But enough about the ice, let's talk about the weather.
I have asserted in the last SIE update that 2010 has a last chance for change as the window of the melting season starts to close and temperatures will be going down to the point that sea water between floes will start to refreeze. This last chance is highly dependent on weather patterns that will once again cause transport and convergence of the sea ice, after the 6 week lull during July and the first part of August that spread out the ice all over the Siberian side of the Arctic Basin and in large part prevented ice from flowing out of Fram Strait.
In the blog post Any way the wind blows, preceding the last SIE update, I wrote that a change in atmospheric patterns was forecasted by the ECMWF medium-range weather forecast. What was forecasted has indeed come about and this is, I believe, the reason that the sea ice extent has been dropping by around 60K for the past few days, which is a pretty decent number for this phase of the melting season.
On the daily updated Arctic weather map from the University of Cologne that I have downloaded these past days we can see how a high-pressure system developed over the Beaufort Sea and has been slowly moving towards the Canadian Archipelago:
The Arctic Oscillation Index is also showing a very negative AO, indicating that the Arctic is currently dominated by high-pressure systems:
So what can we expect? Will 2010's chance to do something remarkable and dip below the 5 million square km mark be extended? This is the ECMWF forecast for the coming 10 days:
A serious high-pressure system is expected to stabilize over the Canadian Archipelago, extending itself over Greenland by Tuesday, with sea level pressures reaching 1030 and even 1040 hPa. This should cause some big winds blowing in a clockwise fashion. Speaking of big winds: another thing I've noticed is the forming of a very big low-pressure area over the Kara Sea. This cyclone might wreak havoc and kickstart the Transpolar Drift Stream, enabling the transport of sea ice through Fram Strait. It will also push the last narrow band of ice away from the Siberian coast that is blocking the Northern Sea Route, allowing our Norwegian friends Børge Ousland and Thorleif Thorleifsson to push forward towards the Northwest Passage that should also be officially announced to be ice-free and navigable soon.
PIPS is showing ever bigger ice displacement arrows pointing in a clockwise fashion. I expect this 'circle' of arrows to move more to the right and get that Beaufort Gyre going for real.
One would expect sea ice area and extent to keep decreasing, perhaps even faster than in the past week. But with the Arctic sea ice you can never be sure about anything. The ice looks so thin and mobile that it just gets pushed around every which way. With the straits and channels in the Canadian Archipelago opening up for transport there might not even be enough resistance for sea ice to be compacted in a serious way, like Patrick Lockerby says in one of the comment sections.
I don't think I'm exaggerating when I say that we have the most interesting part of the melting season ahead of us.
TIPS - Other interesting blog posts and news articles concerning the Arctic and its ice:
I have updated the animations of Peary + Sverdrup and Adolf Gustaf + Ballantyne. The southward transport of the ice in the Canadian Archipelago is very plain to see. The Northwest Passage seems to be practically ice-free as well.
Patrick Lockerby has released the second update of his Arctic Ice August 2010.