ASI 2013 update 4: bye bye, Beaufort

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily Cryosphere Today sea ice area (SIA) and IJIS sea ice extent (SIE) numbers, which I compare to data from the 2005-2012 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything of particular interest.

The animation on the right consists of NSIDC
sea ice concentration maps, one for each ASI update.

Check out the Arctic Sea Ice Graphs website (ASIG)
for daily updated graphs, maps, live webcam images and
the Arctic Sea Ice Forum (ASIF) for detailed discussions.

July 8th 2013

Here's another rehearsal for when I grow up and make good videos with a title roll and background music and everything. By the way, I make a big mistake as I go along. Can you hear what it is?

This update should actually be called 'Bye bye, Beaufort and Chukchi', but it doesn't sound as good. As announced in the previous ASI update the trend lines on various graphs have started to drop precipitously, with thin ice on the fringes (Hudson, Baffin, Kara) disappearing fast.

Despite a slow start unlike any other in recent years, which I described in this recent blog post, 2013 is still hanging in there, slowly leaving the less aggressive melting seasons behind and moving towards the record years of 2007, 2011 and 2012.

The question now is how things will proceed, as the amount of easy-to-melt ice is starting to run out. Even though this year's ice pack consists of a record amount of first-year ice, the weather still plays an important role. The interesting thing about last year's melting season was that decrease rates slowed down somewhat when the weather turned bad in July, but didn't stall, like they did in previous years under similar circumstances.

I think the same will go for this year as well, also because area/extent numbers are quite bit higher, and thus still a lot of melting potential. But there's no telling what could happen if the weather is very conducive to melting/compacting/transport for a week or two, and it looks like we're having some of that up ahead.

Sea ice area (SIA)

July is a month where trend lines on the Cryosphere Today sea ice area graph get divided in the two camps of winners and losers, with 2010 moving from one to the other. Because of steady, substantial drops since the last week of June the 2013 trend line has slowly started to move from one camp to the other.

Here's the graph based on the latest data:

At one point 2013 was trailing 2012 by an incredible 1.1 million km2, but the difference has been reduced to 781K km2. When it comes to century breaks, there have been just as many this melting season as last year's: 32 (with 2010 in third spot with 31 CBs). If 2013 doesn't falter, it could come a bit closer still until the month is done.

Here's the link to my updated CT SIA spreadsheet.

The SIA anomaly has been hovering around the -1 million km2 mark:
Sea ice extent (SIE)

On July 2nd IJIS reported a drop of 208K km2, which is the largest daily drop for July in the 2005-2013 period. Starting the month with 6 century breaks in 7 days, 2013 has finally left that last spot and could very well be in at least 4th position by the end of the month if some of this momentum is maintained. The 9 million km2 mark has also been passed today:

Here's the link to my updated IJIS SIE spreadsheet.

Cryosphere Today area per IJIS extent (CAPIE)

Because extent has dropped just as fast or even slightly faster than area,
CAPIE has been decreasing much slower than in previous years:

Just a reminder of what CAPIE tells us:

When trying to determine how much sea ice extent (SIE) or sea ice area (SIA) the ice pack covers, scientists divide the Arctic up into grid cells. They then look at what the sea ice concentration is within those grid cells. When the concentration is above the 15% threshold, the whole grid cell is counted as 100% ice-covered for SIE. However, for SIA it's the percentage that is counted, which can be anything between 15% and 100%. For both metrics a sea ice concentration below 15% is counted as zero.

This means that SIA will always be lower than SIE, as for instance holes within the ice pack get counted for area, but not for extent (unless they are really big and cover a whole grid cell, or several grid cells). When we divide Cryosphere Today SIA data by IJIS SIE data, we thus get a percentage that tells us something about how much divergence (in other words: holes) there are within the ice pack when the percentage is low, or how much compaction there is when the percentage is high (ie the difference between SIE and SIA is smaller). See this blog post from 2010 to understand how we got to develop this crude metric and have been using it ever since.

At first I was baffled that CAPIE for this year has been so high so far, because the recent persistent cyclone - or PAC-2013 - caused a lot of divergence within the ice pack, showing holes that haven't been witnessed during the satellite era, at least not that early in the melting season. But the answer was rather simple: because of the generally cold conditions this melting season, there has been less melt pond formation.

Now, melt ponds can fool the satellite sensors into thinking there is open water where there isn't, which gets recorded for SIA and not for SIE, causing SIA to drop faster than SIE, and thus CAPIE to go lower as well. This, by the way, is the main reason why scientists prefer SIE over SIA as a measurement, but most of the amateurs here and elsewhere prefer SIA, because melt ponds eventually get drained or frozen over. That leaves the open holes, a more and more common feature of the Arctic sea ice pack, which are better reflected better in SIA data.

A lot of text, but I want to make sure that people understand what CAPIE is:
a crude, but useful tool to determine how compact or not the ice pack is, compared to previous years.

Here's the link to my updated CAPIE spreadsheet.

Regional SIE and SIA

Regional graph of the week, taken from the Regional Graphs page:
Arctic sea ice virtuoso Wipneus has made me a map (based on data by Uni Hamburg, see blog post here) showing the differences that have taken place since the previous ASI update. Red = ice two weeks ago, open water now; blue the other way around:

Now the MASIE product disagrees with me, but I'm under the subjective impression that there is very, very little ice off the east coast of Greenland. I think the Uni Bremen sea ice concentration comparison page for July 7th on the ASIG (Arctic sea ice graphs page) is showing the same. Except for perhaps 2009, no year in the 2006-2013 period has had as much open water in this particular region.

The reason for this is probably two-fold: warm sea surface temperatures (see further below), and either less transport of ice from the Arctic Basin through Fram Strait, or transport of thinner ice that melts out easier. It's difficult to tell what the exact situation is down on the ground, because clouds have been in the way for quite some time now, maybe fooling sensors into thinking there is ice, where there isn't. Last week one could peek just a bit through the clouds and that's when I noticed how dispersed the relatively small amount of ice floes were (image courtesy of Arcticio):

If the - now very blue - fast ice comes loose, SSTs remain high in the region, and transport is low or consists mostly of thin ice, there could be a lot of open water here in August. We'll see what happens.

Sea Level Pressure (SLP)

It's time for yet another animation of Danish Meteorological Institute SLP images for the last two weeks:

With PAC-2013 gone nothing out of the ordinary has been transpiring in the Arctic in the past two weeks. In fact, this is what I referred to as the 'neither fish nor flesh'-setup of atmospheric patterns in my recent blog post comparing this year's patterns with those of previous years, which is actually the set-up that is least conducive to melting/compaction/transport (MCT). It is also reflected in the AO Index, where a negative AO is a sign of high pressure areas dominating the Arctic (usually the best set-up for MCT) and a positive AO is a sign of lows dominating the Arctic (a slightly worse set-up for MCT, except when a Great Arctic Cyclone comes along):

Although the AO Index has been mostly neutral or slightly positive (cyclones dominating) since May 1st, the rate of ice loss has increased in the past week, mostly because of all that melting potential on the fringes coming to fruition. All bad starts come to an end.

And that brings us to the most interesting of all graphs and maps, the 6-day weather forecast by the ECMWF model (click for a larger version):

This is the big one, this is the ideal set-up for large ice loss, this is the rationale behind this update's subtitle (in case anyone was puzzled). It was in the works for a couple of days already, but the forecast needs to be consistent from day-to-day, and now it shows a huge high-pressure area over the Chukchi and Beaufort Seas. Especially the latter region is what separates 2012 and this year (see, again, the Uni Bremen sea ice concentration map for July 7th).

Because of last year's good start to the melting season with lots of clear skies over the Beaufort Sea, there was a lot of melt ponding there that was a prelude to the big crash in June and July. This year the ice was supposed to be thinner than ever, with hardly any multi-year ice to keep things together. I think most of us expected the retreat to be very fast this year, especially after the big cracking event in February and March, but the Arctic is known for doing counterintuitive stuff, and thus the cracking event may actually have let a lot of heat escape that helped make the ice more sturdy. As it stands, the Beaufort region is still almost completely covered with sea ice.

This might now change in the 7-14 days to come. One week at least of maximum insolation seems feasible, as ECMWF has 10 days of 1025-1030 hPa over the Chukchi, Beaufort and Central Arctic regions. The Chukchi looks especially vulnerable to lots of sunlight.

To quote Frank Zappa: Here comes the ice pick in the forehead!

Temperatures

The Arctic is still not showing any signs of anomalously high air temps, especially not over water:

We've almost reached the midline of the bell on the DMI 80N temp graph, but air temperatures north of 80 degrees northern latitude still haven't gone above average (only 2009 looks similar in the last 13 years):

Compared to two and a half weeks ago sea surface temperatures have gone down considerably in the Bering Strait, but up considerably in the Kara and Barentsz Seas. There's some more orange in the Laptev Bite, and a hint of red on the Beaufort coast:

Still looks pretty benign compared to last year.

Conclusion

2013 has started to catch up, and although the easy ice has almost melted out on the fringes, some perfect weather in the coming 7-14 days is probably going to maintain the pace for a while longer. The Chukchi Sea will melt out, there might very well be a total crash in the Beaufort Sea as well, Nares Strait is about to open up, the ice in the Northwest Passage is about to break and melt in situ (just like last year), the Laptev Hole is getting bigger every day and could eventually connect to that huge region of low concentration slush, that extends from the middle of the ice pack all the way to Franz Josef Land.

It looked for a while as if 2013 was out of the running and wouldn't be able to rival last year's record bonanza. That's only logical after such a bad start to the melting season. But this year's upcoming and first streak of weather that is super conducive to melt, compaction and transport might change all that. The next two to three weeks could be incredibly important in determining where this melting season is going to end up and this might teach us more about the million dollar questions:

How far has the shift in the division of power between weather conditions and ice thickness/volume progressed? Is a slow first half of the melting season enough to cause a (temporary) plateau or even a recovery? Or doesn't the ice give a damn?

Next update is in two weeks.

Comments

[Martin Gisser]

Looking at the NSIDC extent graph (instead of Hans' link) I see a good chance that 2013 can catch up: July heads straight down. Extend this line and you get down to 2012.

[Henry1]

A lot of years would pass 2012 if we simply extended the trend line down from mid-July. Extent loss slows down in late July and August which is why we look at area or concentration to get an idea if it will be an unusual late cliff like last year was.

[Jai Mitchell]

even at 2012's currently steeper slope (for same days last year) 2013 is about 79% greater melt on a day to day level.

While I don't expect this pace to continue the fact is 2012 does slow down by about 50% for the last week of July and it won't take much for this year to catch up at current levels (at this rate even if slopes are held steady 2013 would catch 2012 in about 10 days.

[Henry1]

2012 slows down in late July but its a false plateau. It completely craters in August like no other year. So even if 2013 gains close to it by the end of this month, it will have to somehow keep up with 2012 in August which I cannot see happening given the higher concentration of the ice in 2013. It's way ahead in area.

The ice looked horrible last year at this point. http://www.iup.uni-bremen.de:8084/ssmisdata/asi_daygrid_swath/n6250/2012/jul/asi-SSMIS-n6250-20120717-v5_nic.png

One week later: http://www.iup.uni-bremen.de:8084/ssmisdata/asi_daygrid_swath/n6250/2012/jul/asi-SSMIS-n6250-20120724-v5_nic.png

[Werther]

Of course it looked horrible day 198 2012. Melt was one week ahead.

And I'm pointing at the Beaufort Sea here.

I've just stopped comparing the images I had posted on the Forum day 185.
Don't get fooled by the 'static' graphs (like the Bremen maps). They're good in their way.
But things do happen out there. The ice has moved almost 100 km, rotating 22 dg into the direction of the Mackenzie delta. Opening up 65 km West of Banks.
The ice boundary parallel to the coast has held up to the Can-USA border.
More to the West it is now further away than last year.
You won't find it in the numbers, but, while being pushed into the ice free waters, 24K was lost.
Meanwhile, further up the pack, the Feb cracks start showing up. Indicating thinning. And spread. The patterns change rapidly.

I leave further speculation on the melt to your imagination...

[wayne]

Right Werther, Bremen product is better than the Chicago made map, at least when comparing to a NOAA visual picture.

http://www.iup.uni-bremen.de:8084/amsr2/NorthWestPassage_AMSR2_visual.png

Neven, the image above is not exciting compared to last year, but the physics were different, the ice was more compressed, it took months for the gyre current to be overwhelmed this summer, it will not bounce back strong overnight. This is the right way of explaining things:

July 16 Bremen map looks like a traditional September 16 Minima depiction for where the ice should be. We are 2 months ahead of normal, one strong wind with current and momentum all vectoring in the same direction could cause an all time ice melt record any moment. Its a matter of physics. Say we freeze this day until September 15, the ice conditions would be still amazingly different, multi-year ice is mostly replaced with fragile 1st year. Again the record here is beyond the visuals but rather in the details.

[Kate]

I've been watching a fairly strong system spinning in the Arctic. Has been spinning ice out through the Fram for the past day or so. If you want to see the hot air from the US from the link go all the way back and load as many images as you can. The waves through the US/Canada and into the north are quite amazing to watch.

http://weather.gc.ca/satellite/animateweb_e.html?imagetype=satellite&imagename=hrpt_dfo_nir_m_..................jpg&nbimages=1&clf=1

hope that works

[Kate]

Some recent temps around the arctic today
Alert 3C at 09:00 UTC
Barrow 10C at 08:53 UTC
Thule 6C at 08:58 UTC
Resolute 7C at (09:00 UTC
Longyearbyen 10C at 08:53 UTC

These temps have been fairly consistent over the last few days. There are no 0C land temps anywhere within the arctic circle on a 'regular' basis... And it's only July.

[Pjie2]

"Only" July? July is the hottest month of the year for every one of those locations.

[Boa05att]

The Washington Post blogs about the Arctic snow and ice melt -

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/07/18/snow-and-arctic-ice-extent-plummet-suddenly-as-globe-bakes/

[wayne]

It was more than I expected, July 17 272 K melt, lots of it from the Beaufort, is this close to the all time high daily drop?? With this there will be a change in weather dynamics, hold on to your hats we are going for a wild roller coaster ride.

[Jim Hunt]

I'm slightly surprised nobody seems to have mentioned it here yet, but another cyclone seems to be on its way to the Beaufort Sea:

The isobars are a bit close together, but it looks like 980 hPa in the middle by Wednesday. A "wild roller coaster ride" awaits us?

[jdallen_wa]

@Jim

It has been getting some column width in the forums. The consensus/concern about the incipient "GAC2013" is pretty much summarized in:
Hammer (Wind and Rain)
Plus Glass (Fractured, fragile arctic pack)
Plus Anvil (Beaufort Sea and Arctic Ocean)
Equals: dust

[Christoffer Ladstein]

Jim: Are you hinting at the pretty strong low that have been hoovering above the pole for the last days? That one also ought to be able to stir things up like a blender.
Temps at Svalbard have been 2-3 C above normal this summer, expect huge losses at the multiple glaciers. Assume the same for Novaya Zemlja, where temps reached at least 23 C yesterday, thats not very far of records!

[Henry1]

It looks like the weather is turning a lot colder in the arctic basin over the next 10 days compared to what we just went through. The cyclone next week might be the last chance to change the ice dramatically enough to challenge any records.

[LRC]

Now I can not read a weather map to save myself, but I can put 1+1=2 occasionally.
a)You have cold temps building near the NP.
b)You have lots of warm to very warm temps, for the purpose of cyclones, near by.
c)Ready access to cold water near the possible core.
From my limited understanding of core cold cyclones do you not have most of the main ingredients of a long lasting cyclone?
Also GAC2012 to last as long as it did had to do a major job on the ice to get to the water it needed. This time PAC2013 has taken care of that job so that if a GAC2013 gets going could it not be stronger and last longer? Or were the perimeter temps higher?

[Paul Beckwith]

@LRC
I posted a lot of YouTube videos on the August, 2012 massive cyclone (ice thickness, motion, SSS, SST, SSH... and the jet behavior and other meteorology)

I then repeated this for the last 2.5 weeks. Have not fully analyzed this yet, but I think the low coming in 6 days will set up a repeat of August, 2012.

Another similarity is the huge number of fires in the north. In August, 2012 they were in Siberia and this year they are in northern Canada. The ash and heat will be captured if the cyclone is as large as last years.

[LRC]

Sorry about forgetting Youtube possibles. I can handle hitech fairly well, just forget all the time what is out there. Thanks.

[Jim Hunt]

Apologies for any confusion. I hastily linked to an image I uploaded to the forum, but it looks like it was invisible to anybody else! Here's the latest GFS forecast for the Beaufort Sea next Wednesday:

and it still says 980 in the centre.

[Kate]

@Jim Hunt
Nice pic! it is gathering momentum today and for the next few days at least!

[John Goddard]

Visit this site daily. You guys are doing a great job!

SIE lost 227841km on the 16th
and 231813km on the 17th

https://sites.google.com/site/pettitclimategraphs/sea-ice-area

That seems significant to me!

[John Goddard]

Another 2 century drop (200372km) for the 18th.

Potential for clearing from 5 to 4 million km2 in 5 days.