I'm sure there was recent research showing that the sinks (of NE Greenland) had returned back to their 'normal' patterns?
As for the 'freshening of the Basin' there's a lot of melt water (from 'old ice') and lots more outflow from the Northern European/Russian land masses. As to the 'shakedown' from this surface freshening? as long as it doesn't involve 'dark' algal blooms we are probably just playing 'swings and roundabouts' with earlier melting/freezing timings?
I did give this some thought earlier. Unless I am missing something surely the melt water from old sea ice will be saline?
A lot of the salt separates out and sinks when sea water freezes.I have a short explaination linked below.
Edited by user 29 March 2011 05:37:23(UTC)
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As the ice ages it sheds more of it's 'cargo' of salt. the old Paleocrystic was virtually salt free. We now only have young ice so it sheds salt as it forms and traps pockets in it's structure.
That said it may be the final melt out of the old ice that has played it's role in the 'freshening we now see (along with the uptick in discharge from the land).
Another thought is the 'layering' of the surface water of the Ocean. If we are seeing a more active surface layer ,mixed by swells, then we may see this 'new' top layer trapped above the remnants of the old Halocline (now only remaining at depth)?
Thanks AIMSIR, that was helpful.
As I'm sure you've guessed, the whole sea ice/saline system is a lot more complicated than the above,but it's a start.
Edited by user 29 March 2011 14:49:57(UTC)
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No Probs Gandalf.
I've found that most things in life are much more complicated that you expect. I find sometimes that I go through a process starting with thinking I understand, discovering I don't and then disappearing into confusion until the fog clears and I begin to understand properly.
It's very much the case here.
An encouraging late growth spurthttp://www.ijis.iarc.uaf.edu/seaice/extent/AMSRE_Sea_Ice_Extent_L.png
Yes, but only for one day and not at all unprecedented at this point in the cycle.
Last year there was a spurt of almost 150,000 sq km over 3 days at the end of March and close to 100,000 over 3 days in 2009. Similarly in 2006.
Gray-Wolf suggested that the late peaking last year was due to the ice melting and spreading out - remember that the definition of 'ice extent' is an area with at least 15% of ice. I think it is quite possible that the same thing might be occurring but we won't know for a while.
If we check our MODIS images we can see just where this 'stall' is founded. Both the peripheral pack and the coastal/peripheral ice of the basin and fragmenting and drifting.I suggest that to not see 'growth' in extent means 'losses' as the ice is only covering the same surface area (min 15%) yet there is visibly 'less' ice. By May the 15% or more rule will swing the other way with record drops in ice level. Driven not by melt alone but drift also taking all of the peripheral ice beyond the 15% min so rendering the pixel 'ice free'.
The other thing to note is the high AO+ve (forecast to get even higher??) This may not aid transportation (as PIPs shows) but ,come late spring, will result in a lot of sunshine across the basin. As we saw last year even paleocrystic ice succumbs to warm sun and warming waters (South Beaufort sea last July) and how much sub 2.5m ice do we have out there this year (sub 2.5m young ice will melt out over an 'average' season.....before the decline of the nineties and noughties this made up the summer melt for the central pack).
A further thing I have noted from MODIS is the lack of over-ride/pressure ridging going on? Ice appears to just break when ramming another floe leaving a mass of smaller fragments instead of 'healing' the lead??? If this is true then we will see a different July/Aug this year with some of the fastest melt rates ever recorded (I believe). By late July we will know if we are headed sub 4 million and have a feel for just how low the final min will be?
I am happy for the folk seeing 'positives' in this. Last year it was the very high extent and NH Snow cover. Those folk are now more careful about declaring signs of recovery from such augers. This year it may be the stall as the ice collapses around it's edges and melts whilst spreading out. Next year they will be more careful of such after seeing what this type of 'start to the melt season' brought us?
EDIT: The 'ice Bridge in NARES is now collapsing (2 weeks before I suggested?)
It was in place at 10:30 GMT yesterday but failing by 17:30GMT. Seems there may have been a lot of 'drift snow' from the glaciers to the East giving the impression of a thick ice plug but ,in fact, just a lot of wind blown snow. If it's broken and cleared by this time next week I'd 'worry' about the speed of the melt/collapse within the Archipelago itself?
Which brings us to the Candian Archipelago. We saw the last of the 'Channel Ice' melt out there last year so it is comprised of ice similar to Nares. If it breaks up and collapses before June then we'll inherit another drain on the thickest/oldest ice in the basin (the 'thin white line' along Ncoast Greenland/C.A.). The clearing of the channels also allows the spread of warmer waters around the Archipelago.
Things will start to happen fast over the next 6 weeks and give us a better 'feel' for the season ahead!
Edited by user 02 April 2011 12:43:39(UTC)
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Superb image Gray Wolf.The Petermann glacier tongue looks in good condition.
Mabey I am one of those hope er's.LOL
Eitherway ,A superb image.
Edited by user 03 April 2011 14:48:04(UTC)
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Quite a drop over the past 2 days? (164,000)
Hope this is just compaction and not the start of the peripheral 'float off' of ice beyond 15% per pixel cover?
We will know soon enough, I think.
Since the maximum on March 9th we've had three periods of decline so far, interspersed with some brief recovery. Based on the years since 2003 we are in the period now where increases are very rare and mostly marginal. Equally the rate of decline accelerates and daily losses around 50k are common.
Yep we're approaching the time of year when the year-to-year variability is very low, so even less can be read into the little ups and downs. Looking at the graphs it's only by around June at the earliest that the trajectory of the ice loss has any real bearing on September's minimum.
We are still within 250k sq km of the lowest value at this point in the cycle since 2002 and 1.7m down on the 1979-2000 mean. If we have even an average melt season (9.0m sq km) we will be 2nd or 3rd lowest again and a melt similar to 3 of the last 4 years would put us close to breaking the 2007 4.25m level.
The Guardian's report on the research about the increasing freshwater in the Arctic -
A vast expanse of freshwater in the midst of the Arctic Ocean is set to wreak unpredictable changes on the climate in Europe and North America, new scientific analysis has shown.
The water – comprising meltwater from the ice cap and run off from rivers – is at least twice the volume of Lake Victoria in Africa, and is continuing to grow. At some point huge quantities of this water are likely to flush out of the Arctic Ocean and into the Atlantic, which could have significant impacts on the climate. Scientists say they cannot predict when this will happen though.
"This could have an influence on ocean circulation," said Benjamin Rabe of the Alfred Wengener Institute. "It could have an influence on the Gulf Stream."
I'm more concerned with the immediate impacts that the Arctic Amplification is having on our atmospheric circulation myself. The changes that 'could' occur due to freshening of the north Atlantic will not have too great an impact on the N.A.D. as it's 'motion', across the Atlantic, is augmented by it's atmospheric impacts on the Western seaboard of the U.S. (drifting it our way).
We have now turned the corner into melt season proper (no 'balancing act' from now on with losses matching gains) and we await our first 100k loss day (we've had a 160k over 2 days a few days back).
I don't think your comment about the NAD is correct. Firstly I wonder how much the wind influences or drives the current - very little I would think. Secondly, even if the wind did maintain some sort of flow, it would be much less warm water if the ocean conveyor was weaker or turned off.
As we keep repeating, the global climate system is highly complex, full of interdependencies and has non-linear responses to changes in inputs. This news is just such an example, i.e. a gradual build up over years of fresh water in the Arctic basin followed potentially by a tipping point if it spills out into the Atlantic and disrupts the sink mechanism upon which the thermohaline circulation depends.
Losses of 100k or more in a day are actually exceedingly rare in April and rare May.
Taking April and May since 2003:
2003: April - 0, May - 0
2004: 2 & 2
2005: 0 & 0
2006: 1 & 2
2007: 0 & 0
2008: 1 & 1
2009: 0 & 1
2010: 0 & 3
So, over 8 years only 4 occasions (out of 240) in April and 9 (out of 248) in May.
New warning on Arctic ice melt
Scientists who predicted a few years ago that Arctic summers could be ice-free by 2013 now say summer ice will probably be gone within this decade.
Original ice-loss predictions were for an ice free summer some time around mid-century. I still consider that a possibility, but also possible is that the ice will detstabilise and sometime in the next 10-20 years it goes kaput. I give that latter viewpoint much more credence given that ice hasn't really had a recovery to speak of since 2007's extreme loss.
It really doesn't surprise me that they've pushed the prediction back from 2013 though.
It will depend to an extent on the definition of 'ice free'. If this means no solid ice area then that is obviously more likely than nothing above 15% coverage (the current definition for 'ice extent'). Completely free of ice seems unlikely in the near future.