It looks like the ice floes in Baffin Bay didn't compact too well during the winter. Instead of slabbing and compacting, the floes appear to have merely become congealed together with winter ice. That ice is now first year ice. 'First year' doesn't imply year-old: the ice which surrounds older floes in Baffin Bay is just over 6 months old.
As ice forms over sea water it traps pockets of water. Over a period of time the ice in effect squeezes the salt water out through the bottom. This makes older ice less salty. Salty ice is a matrix of ice crystals surrounding pockets of water. That structure makes the ice somewhat flexible and weak: the younger the weaker. Salty ice also melts faster than fresh-water ice.
Recent images from the Arctic mosaic show cracks in the newer ice running outside of the older ice. This appears to me to be yet one more positive feedback in the ice-melting saga. Previously the ice in Baffin Bay has built up in thickness by slabbing. It takes much more energy to crack thick multi-year ice than to crack the first year ice that surrounds last year's floes.
The images below, all taken from Arctic mosaics, compare ice on March 22 2009, 2010 and 2011.
March 22 2009
March 22 2010
March 22 2011
March 22 2011 in more detail
My expectation is that this ice will break up, disperse and melt rapidly as the melt season gets fully under way. Baffin Bay ice usually presents a great obstruction to the export of ice from Nares Strait and the Canadian Archipelago. I suggest that it will not continue to do so for long.
Images courtesy http://rapidfire.sci.gsfc.nasa.gov/
Neven: I finally figured out how to jump through all the hoops to get logged in and on the full editor page. Thank you for letting me in as a guest writer. I do hope I haven't broken anything. ;-)
Posted by: logicman | March 22, 2011 at 22:54
Patrick, interesting stuff. :) Is there still an ice bridge in the Nares? If so, how long do you think that it is likely to remain?
[i'm currently having trouble accessing your blog, so you might reply here]
David
Posted by: Evilreductionist.blogspot.com | March 23, 2011 at 04:05
If there is an ice bridge in the Nares still, it's not anymore where it was a week ago. Currently clouds are blocking the wiew. Kara Sea area looks to be in the beginning of the melt, though it may take a while to get in speed since the export from the central basin.
Posted by: Erimaassa.blogspot.com | March 23, 2011 at 04:54
Great stuff, Patrick! And you didn't break anything which is even greater! ;-)
I can't imagine that big red blob of anomalously high SST off the coast of Newfoundland isn't having an effect on the ice in Baffin Bay.
Kara, Bering and Barents are the other places of interest, and Nares of course, but only if clouds permit. I noticed that on the Cryosphere Today area maps Kara has dropped quite a bit, as has Barents. I think those huge leads off the Siberian coast that can be perceived through the mist and clouds have something to with that. The Bering trend went up for a while, but has dropped again.
That huge lead off the south coast of Novaya Zemlya (and the rest of the Siberian coast) must have led to some substantial slabbing/compaction. I wonder how that will pan out when the melting starts for real. Will it put a brake on melting in the Barents Sea and Kara Sea?
Posted by: Neven | March 23, 2011 at 10:55
The ice bridge in Nares Strait is still there, holding up surprisingly well. ASAR radar images show it hasn't moved in weeks: http://ocean.dmi.dk/arctic/kane.uk.php
(But surely its just a matter of time...)
The current that works up the west coast of greenland has caused a lot of movement below Kane Basin, but above the bridge, everything is locked solid. A few days ago, ice that "should" have moved down Nares got sick of waiting and started heading off NE across Lincoln Sea. It will probably finish up passing through Fram Strait instead.
I agree with Neven that that huge Novaya Zemlya lead must have led to slabbing. While SST's have been high, it has mostly occurred because of a series of lows to the north generating persistant strong westerly winds, which has blown the ice away from the east coast of Novaya Zemlya. I'd guess the fact that it has moved so easily suggests it was pretty thin before any slabbing that might have happened.
But the ice in Baffin Bay looks really poor - we're seeing CT area there climbing steadily, but surely its just the weak ice "glue" between bigger older floes giving way and allowing spreading.
Posted by: FrankD | March 23, 2011 at 12:10
Hi Frank D et al,
Frank, you mentioned about a month back that something odd and grey was blocking the Kane Basin.
If its still there I regret not posting what sort of occured to me at the time, as a slightly tongue-in-cheek suggestion:
Could that perhaps be the Humboldt Glacier?
The big red blob Neven has highlighted above is a fairly constant feature that began in November 2009 and has persisted since.
Posted by: idunno | March 23, 2011 at 14:24
What is also interesting - at least, I find it is - is comparing the entire Mosaic of a few days back (very clear on the Canadian side) with the same date last year (coincidentally quite clear as well, except for Nares unfortunately):
2010 vs 2011
Posted by: Neven | March 23, 2011 at 19:52
Nevin,
Can you get a picture of the ice that makes that big orange blotch curving North East from Svalbard up to the pole over at Cryosphere Today? Could that be the Atlantic warm water coming through? Is the ice from that area going out the Fram Strait? It looks like the ice is thinning when it should still be freezing.
Posted by: michael sweet | March 24, 2011 at 02:14
>"What is also interesting - at least, I find it is - is comparing the entire Mosaic of a few days back (very clear on the Canadian side)"
Yes I like the full mosaic comparison to last year.
A few days back I though it looked like there were a lot of cracks in 2010 along the archipelago compared with solid ice in 2011.
However now:
http://rapidfire.sci.gsfc.nasa.gov/subsets/?mosaic=Arctic.2011082.terra.4km
There is a lead in 2011 and the 2010 cracks look more like they are old cracks that had iced over. While this possibly make me more concerned about ice entering Archipelago via northern entrances earlier, I still think it will only be late in the Season. Patrick is more likely to be right than me but I think he is overdoing the importance and the amount of ice that could flow though Archipelago.
Posted by: Gas Glo | March 24, 2011 at 14:04
Michael Sweet, when I started observing the ice real closely for the first time last year, I was also impressed by those changing colours on the CT sea ice concentration map (and to a lesser extent on the Uni Bremen map, for instance here and here), but concluded after a while that most of the time they don't mean much. Whether they are sensor glitches or clouds or whatever, they just don't mean that much right now.
However, somewhere in June is when the large melt ponds on the ice start to show up and fool the sensors into thinking the ice concentration is low. That's when you see huge blotches of yellow, orange and green swerving all over the place.
Posted by: Neven | March 24, 2011 at 16:10
Nevin,
I know that after June the blotches are often caused by melt ponds on top of the ice. These color splashes look a little different to me. It is too cold for melt ponds to form so they must be from something else. We will see in a month if the ice is thin there or if it is just the sensor acting up.
PIPS today showed a lot of ice going out Fram Strait. I hope the NSIDC talks about how much ice has left the Arctic this winter. They will update in 10 days or so.
Posted by: michael sweet | March 25, 2011 at 00:38
The yellow splodges on CT are almost exactly following the areas of maximal displacement on the PIPS chart for the previous day.
http://www7320.nrlssc.navy.mil/pips2/archive/retrievepic.html?filetype=Displacement&year=2011&month=3&day=22
That says to me that the "low" concentration areas (mostly still above 90% though) are due to leads opening up as the ice gets shunted around.
Whether this is a good or bad thing is unclear - presumably the ice around the leads is getting ridged/rafted and thus thickening, however the leads themselves will ice over with thinner, more fragile ice.
Posted by: Peter Ellis | March 25, 2011 at 10:44
Looking at MODIS pix: http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c02.2011085.terra
The ice in Nares Strait below the ice bridge has been breaking up, and the cracking front has reached a points about 20 km's below the bridge. Its easier to see on the 250 m scale, but the cracking can be seen at the narrowest part of Nares Strait, while the ice bridge is the grey curve to the right of that point.
Its very hard to tell - due to intermittant views - how fast that leading edge is moving north, but I would guess that it will reach the bridge some time this week.
When it does, I suppose a lot of ice will move down Nares Strait which will probably to "good" things for extent measures in Baffin Bay in particular, but that will be at the expense of sucking volume out of the central basin.
We are also about a week away from the "pole hole" (that was the name Neven settled on?) being filled in, and getting 100% coverage!
Posted by: FrankD | March 27, 2011 at 10:18
I've covered the Nares Strait breakup in my latest update. I'll be reposting an updated version of that update on http://www.skepticalscience.com/.
I think Neven is going to write about Nares also.
The melt season is well under way and the race is on - between me and Neven. ;-)
http://www.science20.com/chatter_box/arctic_ice_march_2011_update_2-77499
I'll post the SkS link here as soon as I've finished editing.
Posted by: logicman | March 27, 2011 at 13:36
Nevin, you made a point about the color coding on CT. Your comments seem to relate to false readings during the melt process. This winter, though, the CT color coding indicated a lot of light purple, reds, and yellows, which should mean coverages in those areas from 85% to 97%, approximately. Do you think that those winter readings were wrong? Previous years did not show such readings. I am inclined to accept them as real, which has great implications for this summer's melt. Am I wrong?
Posted by: Craig Dillon | March 31, 2011 at 18:22
Previous years did show such readings, at least if you look at the higher res images. Where you *don't* see them is in the smaller thumbnails used for the side-by-side comparison tool - but in that case you don't see them for this winter either.
Posted by: Peter Ellis | March 31, 2011 at 19:18
@Peter Ellis: Previous years did show such readings, at least if you look at the higher res images
?
Which higher res images do you mean, Peter? The high resolution images here:
http://arctic.atmos.uiuc.edu/cryosphere/archive.html
are the basis of the thumbnails for the comparison feature, and use the same colour scale (where everything above ~70% is pink).
Do they have an archive using the same scale as their daily images (ie where 80% concentration = green, not pink)?
If so, I can haz link?
Posted by: FrankD | April 01, 2011 at 14:59
As far as I'm aware CT don't archive the hi res versions, when I want to make such comparisons I use the uni-bremen maps:
http://www.iup.uni-bremen.de:8084/amsredata/asi_daygrid_swath/l1a/n6250/
Phil.
Posted by: me.yahoo.com/a/nSjChi4X3vr8X3DRw93GkY1.cerja.8nvWk- | April 01, 2011 at 17:01
Strange, I was sure I'd looked through an archive of figures at some point. Must have been remembering the Bremen ones. The point stands that this year doesn't seem grossly out of line with previous years across the central basin
Posted by: Peter Ellis | April 01, 2011 at 19:41
Hi Craig Dillon,
Do you think that those winter readings were wrong?
Wrong is a big word, but I think one should be cautious in assigning too much meaning to those swathes of colours (up to certain point in time of course). The SIC (sea ice concentration) images of Uni Bremen are a bit more conservative when it comes to that, but I think it's still useful to have a look in the archive that Phil. posted.
I'll have a look too after this weekend and compare with dates in previous years.
And remember, it's always good to cross-check with MODIS images. Apart from some big leads here and there in the central ice pack I don't think I'm seeing anything out of the ordinary, but as said before, I didn't really started gazing at satellite images since June last year.
Posted by: Neven | April 01, 2011 at 20:55