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.
August 6th 2011
We have seen about 3 steps back since weather patterns shifted in the Arctic about 3 weeks ago. But they have been shifting again, and this has now resulted in one step forward. It's quite a big step forward, as some extent decrease potential had been building up during the slowdown. In the meantime, area decrease hasn't really let up and 2011 is still leading the pack there. Needless to say, things are fascinating to watch.
It was only around mid-August that 2010 started to flip back again, so if this current transition sticks around for a while, the slowdown was half as long as last year's. Which explains why 2011 is still a contender, where 2010 had thrown in the towel by now.
It's not a done deal that 2011 will now cruise towards the finish and take the trophy, though. Those big highs I mentioned in the last SIE update have taken position. They are not ideally placed, but very big and pretty strong too. They will stay that way for the next couple of days, so this is bound to have an effect. But during the slowdown 2007 managed to take a big lead, at least when it comes to IJIS sea ice extent. If 2011 can manage the damage and nibble away at that lead we're in for a formidable finale. It won't be easy.
I stand by what I said in the previous SIE update: if by August 10th the difference between 2007 and 2011 is more than 200K, we can effectively rule out a new minimum extent record. August 10th is just a few days away, so I don't think the difference will be less than 200K, but if 2011 makes an extra effort, the extent decrease rate speeds up, and weather patterns more or less stay as they are, I'm willing to take back what I said.
Sea ice extent (SIE)
Here's the current IJIS SIE graph:
The gap between 2007 and 2011 can clearly be seen, but so is the downturn in the red trend line. IJIS reported a century break for yesterday's date, and almost a century break the day before. With the current weather patterns and the compaction potential I think we could be seeing 1 or 2 more century breaks in the coming week. This could be enough to start creeping towards 2007, which has ended its final century break series, or at the minimum stay well ahead of the others. Except for 2008 all other years have run out of century breaks.
The current difference between 2011 and the other years is as follows:
- 2005: -366K (-45,000)
- 2006: -483K (-37,697)
- 2007: +422K (-57,041)
- 2008: -529K (-70,333)
- 2009: -378K (-48,654)
- 2010: -227K (-51,736)
Between brackets is the average daily extent decrease for the month of August. 2011's average daily extent decrease for August is currently -49,563 square kilometers, but the month has just started, and this year's August started very, very slow.
Sea ice area (SIA)
Whereas 2007 has sprinted off on the SIE graph, the story is quite different in SIA land. 2011 has continued to decline relatively fast and is still leading the race. The lead over 2007 isn't big, just 49K, but it's there, as we can see on pdjakow's excellent Cryosphere Today sea ice area graph:
Naturally, this means that the Cryosphere Today SIA anomaly graph never has been as low either for this time of year:
As we can see on the Regional Graphs page, the SIA in the Arctic Basin has been going down steadily in the past week, as it has in the Canadian Archipelago, where a lot of the ice is melting in situ. Sea ice area in the East Siberian Sea is having another small hiccup, while renewed ice transport towards Fram Strait has SIA in the Greenland Sea going up again. Prior to this some of the transport had been towards Siberia for a couple of days, and I think that explains why Kara and Laptev haven't hit their minimum yet.
Cryosphere Today area per IJIS extent (CAPIE)
Our CAPIE percentage has been very low for the time of the year, below all other years. It's a sign that the ice pack has been diverging, causing that slowdown in extent decrease. 2011 hit a temporary bottom of 60.25% yesterday, which was already below the minima of 2005, 2006, 2009 and 2010. It will probably start going up, now that SIE decrease is underway again:
Sea Level Pressure (SLP)
Time to have a look at what has happened exactly with those weather patterns. Here's an animation of SLP images from the DMI Centre for Ocean and Ice of the past week:
We can see how the low-pressure area that was keeping the Arctic in its grip, started to lose that grip. In the meantime, a high between Greenland and Scandinavia started building up and moved slowly northwards. This isn't an ideal set-up for ice transport, but it moves the ice about nevertheless, produces clearer skies (there is still some extra insolation going on right now) and pulls in warm air from Siberia. Hence, a greater extent decrease.
The Arctic Oscillation is forecasted to stay negative for a while longer, meaning the high is there to stay in the short term. We can see what it's probably going to do the coming 5 days on this animation of the ECMWF forecast:
That high is going to position itself over the central Arctic and is getting pretty intense in the process. We haven't seen a lot of pressures of 1030 mb so far. I'm even seeing 1035 mb after this 5 days forecast, but there's not much sense in looking too far ahead, as these forecasts get updated a couple of times a day.
Update conclusion
I was expecting the slowdown to continue for a while longer, but after some changes at the end of this week, it seems to have stopped and SIA and SIE decrease are back in business.
Ice transport towards Fram Strait will seriously get underway the coming week. In fact, it has started already. If that high really gets to develop the way it is forecasted, I'm expecting extent decrease to make up for the relatively slow two weeks we have behind us and get below 6 million before the next SIE update.
What happens after that is up for grabs, but 2011 hasn't disappointed us much so far.
---
TIPS - Other blog posts and news articles concerning the Arctic and its ice:
New York Times: Shell finally has its coveted preliminary approval for drilling in the Beaufort Sea.
Lucia from the Blackboard has been having fun recently with Arctic sea ice statistics.
But if something goes wrong, they can only clean up 4 days out of 5 (if we're lucky).
sorry I mean day numbers it goes from 2011221 to 2011223
Posted by: Philiponfire | August 13, 2011 at 01:15
IJIS prelim is -64k. Decrease holding steady...
Posted by: maltose | August 13, 2011 at 05:13
Yes, a hefty but not stunning decrease.
Posted by: Kevin McKinney | August 13, 2011 at 05:19
A slaughter of the ice is still possible in the East Siberian Sea. Check out what happened in August 2008...
http://igloo.atmos.uiuc.edu/cgi-bin/test/print.sh?fm=08&fd=12&fy=2008&sm=09&sd=01&sy=2008
Posted by: maltose | August 13, 2011 at 05:26
Starting with 8/12/07 the following week averaged 43,192 and 60k was hit only four times in the remainder of the annual melt.
64k is a catch-up number. If weather predictions hold some ground should be gained over the weekend.
Posted by: Bob Wallace | August 13, 2011 at 06:21
Re Philiponfire | August 13, 2011 at 01:15
That was my point of query, sorry for not making that clear. Problem with this, leaving out day records, that if you plot this out as-is, you get the weirdest visuals unless one starts infilling the missing dates when charting. Looking at the CA Regional chart they definitely do plot along the full calendar and connect the available data points. Now that I know, applied a few changes. Having to look up the dates to put the data points in the right place is a painful way with the software I use. Cannot rely on logic like "what's the difference between yesterday and the day before". Found a similar problem with plotting ACRIM and SORCE TSI in 1 chart. SORCE in-fills missing records and puts a -9999 line in, so you know, and ACRIM just skips forward, with sometimes multi-day to a week and more missing records. My problem though. :|
Posted by: Seke Rob | August 13, 2011 at 11:45
so it looks like the SEARCH August 2011 outlook is out already
http://www.arcus.org/search/seaiceoutlook/2011/august
Posted by: k eotw | August 13, 2011 at 12:33
Neven, new Search ice outlook is finally out:
http://www.arcus.org/search/seaiceoutlook/2011/august
with mean at 4.6 mio km2.
Posted by: Patrice Pustavrh | August 13, 2011 at 12:33
Personally I like the below linked view better than the one with Greenland at the low side in this phase of the melt: http://arctic.atmos.uiuc.edu/cryosphere/NEWIMAGES/arctic.seaice.color.003.png
Now, don't look at the ice... it's depressing, look at the open water, is there massive plankton bloom in the Arctic Ocean?
Posted by: Seke Rob | August 13, 2011 at 14:11
IJIS is now at 5827500 km^3 for August 12th, down 12,500 from the prelim. Could mean a big day for the 13th...
Posted by: maltose | August 13, 2011 at 16:08
Whenever you see for JAXA a wild number with e.g. 4 zeros at the end, it's a sign they've plugged a number to fill the hunger for... a number. Yesterday now gains 30k on 2007... 406,406 kmsq behind, on extent. Their Area chart flatly overlays 2007. Once send them a mail if they could publish their area dailies, but the reply was, that it was not in their mission. Think many would love a single source daily for Area+Extent.
Posted by: Seke Rob | August 13, 2011 at 16:58
Seke Rob said:
Um, no:
6.25km x 6.25km x 149,184 cells = 5,827,500.0 km^2 sea ice extent (SIE), exactly.
Please don't invent explanations, when it is so easy to ask on this very friendly forum. There is already ample misinformation on Arctic sea ice.
Regards,
Lodger
Posted by: Artful Dodger | August 13, 2011 at 17:40
Point taken, but I was talking about the initial number 5840000 of prelim... those have odd numbers.
Posted by: Seke Rob | August 13, 2011 at 17:49
I was off-line for two days, and I just want to thank everyone for the excellent comments (these are the heart and soul of this blog).
And thanks for letting me know about SEARCH. Post will be up in a minute.
Posted by: Neven | August 13, 2011 at 18:00
Seke Rob:
149,504 cells x 6.25km x 6.25km = 5,840,000 km^2 SIE
Hey, this is fun! Now you try one!
Posted by: Artful Dodger | August 13, 2011 at 19:00
Dodger, does nature create 149,504 or any other 'random' set of cells that exceed 15% or more sea ice that total, so they multiply to 5840000 or 6595000 or 7895000 or 7525000 or 9740000 or 9815000? Calculus is one, you had your fun, getting to know why these odd numbers come out in such high frequency is another, those 5 earlier on quick peruse since June. Are they using more raw masks or a variation of masks, depending on what larger quadrants image properties are? They note a higher error potential on their chart page, which makes roundings not improbable. It's an observation, of very low importance.
cheers
Posted by: Seke Rob | August 13, 2011 at 19:22
It looks to me like all the JAXA numbers are divisible by 12.5 twice meaning a 0000 end every 64 days on average.
Lodger are you sure it is 6.25km not 12.5km 'squares'?
Posted by: crandles | August 13, 2011 at 20:31
Bob Wallace: "I'm returning to my previous idea that wider spread ice is going to suffer more bottom melt. In addition to having more room for wind/wave and sunlight to impact its edges."
I don't know about the bottom melt as such, but Rampal et al. point to the latter as a big factor. AIUI the low-conc. ice tends to grind itself into smaller and smaller pieces, which become progressively more prone to melting.
Posted by: Steve Bloom | August 13, 2011 at 23:58
Hi Chris,
You are quite right. No two unique IJIS SIE values are closer than 156 km^2, so they must be using a 12.5 km grid. Thanks for pointing that out :^)
The native resolution of the AMSR-E sensor is 6.25 km according to NASA's AMSR-E Science webpage. Also, the Uni-Bremen Daily Graph says this in the bottom-left corner:
However, I see that there is also a 12.5 km gridded sea ice product for AMSR-E, so that's almost certainly the resolution they use at IJIS.
Cheers,
Lodger
Posted by: Artful Dodger | August 14, 2011 at 12:06