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.
July 23rd 2011
As I concluded in the last SIE update sea ice extent decrease has slowed down a bit, but despite some similarity to 2010, it's the differences that stand out.
Most of you will remember how 2010 was going down hard, when all of a sudden atmospheric conditions in the Arctic altered radically. Low-pressure areas moved in and kept almost all of the Arctic in a deadlock for a month and a half, resulting in one of the lowest extent decrease rates for July in the IJIS dataset (starting 2002) and some spectacular satellite images of a massively diverging ice pack.
This past week low-pressure areas have moved in as well, and extent decrease has slowed down, but this year's low isn't as low as last year's low (and will stay not so low for a while to come). Extent decrease has slowed down, but area decrease has been picking up, which has had consequences for CAPIE as well (more below). And last, but most certainly not least, the distribution of low-pressure and high-pressure areas is different from last year.
What we have been seeing the past couple of days is the so-called Dipole Anomaly causing ice to be blown away from the Siberian coast and transported towards Fram Strait (I have started an animation to keep an eye on progress over there) by the Transpolar Drift Stream. If this keeps up, a lot of ice will be blown through Fram Strait and melt out at lower latitudes, AND that huge warm water polynya in the Laptev Sea is going to eat its way through the first year ice towards the North Pole. These effects could seriously come into play towards the end of the melting season.
The key question is, of course: will it keep up? Is it one step back, and then two steps forward? Or will we see a repeat of 2010?
Sea ice extent (SIE)
Here's the current IJIS SIE graph:
2011 has just passed the 7 million square km mark, one day earlier than 2007, but despite this we can clearly see 2011 bending off towards 2007, as there were a few low extent decrease days this past week (one day of 30K being particularly low). At the same time 2007 is landing a few punches with a small series of century breaks. It still has 5 days of relatively high daily extent decreases coming up, so it remains to be seen if 2011 will remain in the lead (probably not).
The current difference between 2011 and the other years is as follows:
- 2005: -782K (-83,709)
- 2006: -723K (-70,025)
- 2007: -101K (-98,608)
- 2008: -1024K (-81,068)
- 2009: -717K (-92,127)
- 2010: -593K (-62,601)
Between brackets is the average daily extent rate for the month of July. 2011's average daily extent rate for July is currently -99,197 square kilometers, which is 15K lower than last week. Here's the average other years had after the first 22 days of July:
- 2005: -86,058
- 2006: -73,899
- 2007: -107,536
- 2008: -81,527
- 2009: -96,783
- 2010: -59,261
- 2011: -99,197
Sea ice area (SIA)
I was doubting a bit this past week if 2011 really was record material, as SIA (and by consequence CAPIE too) was lagging behind. But in the past couple of days area decrease has accelerated quite significantly. This has caused the trend on the Cryosphere Today SIA anomaly graph to shoot down to over -1.7 million square km:
Because of the increase in ice transport towards Fram Strait, the SIA anomaly in the Greenland Sea has shot up (it was relatively high to begin with). Something to keep an eye on. In the Arctic Basin SIA has gone down some more, although extent has gone up a tad. In the Canadian Archipelago both SIA and SIE are going down hard, probably having to do with the ice in the Northwest Passage and between the islands of the Archipelago starting to crack up all over the place. Sea ice area in the East Siberian Sea is still dropping very, very fast.
Cryosphere Today area per IJIS extent (CAPIE)
With area going down much faster than extent,our CAPIE percentage has taken a nosedive and is currently lowest in the 2005-2011 period:
As I've shown in the last SIE update, the high that was stuck over the Beaufort Sea weakened in strength and moved towards the Canadian Archipelago, while low-pressure areas were starting to form off the Siberian coast. Here's an animation of SLP images from the DMI Centre for Ocean and Ice of the past week:
A very weak high on the North American side of the Arctic combined with a big low on the other side (very big today) is pushing the ice out towards Fram Strait, as can be seen on the PIPS ice displacement forecast maps:
In the past two days the arrows aren't pointing as clearly towards Fram Strait, probably due to that very big low. This could mean that the Dipole Anomaly is already losing its effect, unless a high over the Canadian Archipelago reforms.
So what can we expect the coming few days? According to the NOAA Ensemble Mean AO forecasts the Arctic Oscillation will continue to remain fairly neutral the coming 7-14 days, perhaps even going slightly negative after August 1st:
And here's the ECMWF forecast for the coming 5 days:
The weak highs over the Canadian Archipelago are forecasted to be pushed out completely by lows. This would mean the Dipole Anomaly was short-lived and we won't be seeing a large increase of ice transport towards Fram Strait in the coming week. But as the AO remains fairly neutral, all it needs is the right distribution of highs and lows for transport to pick up again.
I'm not expecting extent decrease to radically stall like it did last year, but I'm not seeing any century breaks coming about either the coming 5-7 days. I was hoping we'd see more of that fast ice transport toward Fram Strait to see what it would do to the SIE and SIA numbers, but the highs aren't in the right place. The low off the Siberian coast is pretty strong right now, but is forecasted to weaken in the coming days. It'll be interesting to see what happens.
At the moment 2011 is neither fish nor flesh. It could very well be losing its 100K lead to 2007 in the coming week.
TIPS - Other blog posts and news articles concerning the Arctic and its ice:
I have updated the Northwest Passage animation.
Patrick Lockerby has written an update to his Arctic Ice July 2011 analysis.
Gareth Renowden has done an update on the current situation in the Arctic: Wet, wet, wet
AGW poet Horatio Algeranon has written a cover to a Steam song: Na Na Hey Hey Kiss the Sea-Ice Goodbye