Barrow Break-up 2

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:

There's a very good explanation on the Barrow Break-Up forecast webpage that describes what happens during the melting season:

Break-up proceeds in two stages: Initially, ice shoreward of grounded pressure ridges begins to move collectively along the coast, followed by a period of sporadic break-out events of individual grounded ridges. After the disappearance of the snow cover in the first half of June, landfast ice closest to the shore weakens structurally due to solar heating of dirty ice and under meltponds. Eventually, regular winds are able to push the ice along shore. With reduced snow cover, more solar energy is absorbed and the oceanic heat flux to the ice increases, eroding grounded pressure ridges from below.

Previous years

The stabilizing influence of grounded pressure ridges can vary from year to year. As explained on the 2011 Sea Ice Break-Up Forecast webpage:

Some years in the past (2002, 2003, 2004, 2007) have seen insufficient stabilization by grounded pressure ridges, leading in 2004 to the sudden disappearance of the entire coastal ice within 24 hours as early as 18 June. These cases cannot be predicted with the approach presented here. However, if grounded ridges are present, break-up should take place in the first half of July, with some grounded ridges possibly persisting into early August.

This year those grounded pressure ridges did form alright, and quite seriously too. Tzupancic1 posted a link in the comment section of the previous Barrow Break-up to an article in the Arctic Sounder that starts with "towering pressure ridges off the coast of Barrow have delayed access to open-water leads where subsistence whaling happens, leaving crews far below their usual catch at this time".

The article was accompanied by this photo (courtesy of Craig George):

I have collected some webcam images from previous years to compare to this year. Some of them I retrieved from this archive, 2006 and 2007 are still images from these time-lapse videos that have been posted on Youtube. I can recommend those, and not just because of the great accompanying music. Here are the webcam images from 2006 to 2011 (click for a larger version):

Except for the melt ponds on this year's webcam image and some more snow on last year's webcam image, I don't see a lot of differences with previous years, but give a shout in the comment section if you notice something.

As we saw in Barrow Break-up 1 melt ponds formed early this year, due to a high pressure system dominating the North American side of the Arctic. This led to relatively clear skies (more insolation), higher temps and the Beaufort Gyre starting to turn (see last SIE update) and pushing away the ice pack from the coast of Alaska.

It will be interesting to see the dynamic interaction between the "towering pressure ridges off the coast of Barrow" and weather conditions, especially if they remain unfavourable (for ice). In the meantime we'll await the first update (around June 5th) from the pros over at the Sea Ice Group of the Geophysical Institute at the University of Alaska Fairbanks.

Comments

[Artful Dodger]

I watch this temperature profile chart from the Pt Barrow Sea Ice Mass Balance Site:

Amazingly, the temperature in the middle of the sea ice layer has increased from -4 C a few days ago to -2.5 C now...

Neven, would you consider replacing one of the non-updating graphics on your Sea Ice Graphs page with this one?

Cheers, Lodger

[R. Gates]

Thanks for the Barrow breakup update. Based on my current analysis, I expect the forecast to show the date for the breakup right smack between the June 27th line and the July 4th line...so right around June 30th.

[Neven]

There's a preliminary forecast on the UAF Sea Ice group webpage:

Current forecast for break-up: after June 14

[Artful Dodger]

Hi Neven, your link seems to be 'under-populated'...

[Timothy Chase]

Dodger, I think Neven meant:

2011 Sea Ice Break-Up Forecast for Barrow, Alaska
http://seaice.alaska.edu/gi/observatories/barrow_breakup

... which currently gives:

Current forecast for break-up: after June 15
Break-up can be forecast no more than 16 days in advance

[Artful Dodger]

Thanks Timothy. That's an important distinction. "Not before June 16" does not mean they are predicting a June 16 breakup.

[Artful Dodger]

"The mass balance probe has been recovered for the season on 7 June 2011..."

"Ice thickness may be incorrect since June 1, 2011 due to melt at the site."

http://seaice.alaska.edu/gi/observatories/barrow_sealevel

[Rob Dekker]

Thanks Neven, for this focus on the Barrow break up. And Timothy, for the link to the 2011 projection.
Considering that most of the break ups at Barrow occurred between July 4 and July 11, I am not surprised that this year's projection is "after June 24" or whatever the current prognosis entails.

Even though it is an interesting metric, since the break up at Barrow pertains only to land-bound ice and seems to keep little correlation with minimum sea ice extent, I doubt that it has much to do with the overall state of the Arctic Basin sea ice, or Arctic sea ice state in general. Anyone cares to dispute that statement ?

[michael sweet]

Rob,
All the data available needs to be considered. When the multi year ice is gone will the first year ice continue to form the same thickness or thinner? The Barrow ice gives data to see what will happen. There is a lot of year to year variation, and the record is short, but as more years are collected the pattern will show. If the sea ice at Barrow starts to break up earlier in the melt season that indicates the rest of the ice is getting thinner also. The Canadian Ice Service has some data on ice north of Barow that shows it is melting more every year.

[Gas Glo]

Break up forecast is now 'on' 8 July rather than 'after' 16 days.

[Neven]

Thanks, Gas Glo. I think I'll do an update tomorrow.