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Magma

Excellent guest post, Alek. Logical and clearly written explanation of a phenomenon that I (and likely some other readers) have been watching without necessarily grasping many of the interesting details, including the changes over the past decades. Thanks.

wayne

I particularly like the sketched about old and new sea ice with respect to winds. The missing one may be new sea ice, mostly flat, only having "sails" by much lower smaller pressure ridges. This fits with respect to another missing component, the newish counterclockwise gyre driven by persistent lower pressure cyclones during summer and also very lately winter, in effect, creating no gyre at all. There is no circulation, just melting in place ( summer 2013-2014). It is a natural defense against total eradication by compaction. Sea ice onto itself is equally complex, either thin or thick, boundary layers exist, and sometimes boundary layers increase surface interface wind speeds, a particular not so rare occurrence especially during the long night.

D

FishOutofWater aka George here.

With the warming of Alaskan waters the Bering strait is ice free longer and more warm moderately salty water is entering the Arctic from the Pacific, especially in the fall. Good measures of the mass balances of salt and water are needed to model the stability of the water in the Beaufort sea. Unfortunately, many of the buoys have gone out of service and sampling of the depth profiles and currents is very thin.

This year the high pressure is much more persistent so the wind push on the ice is probably more efficient than when the winds are briefly strong but of variable direction. Summer 2014 was good for building ice in the Arctic because there was little net motion despite all the highs and lows.

Good post. Thank you for telling us about the excellent research.

Aaron Lewis

Thank you very much. I had thought about this, and it is very nice to see that others get the same answers.

Um, does the rapidly moving keels of thin ice stir the fresh water lens more than the slowly moving keels of thick ice? That is, with increased continental melt has the fresh water lens gotten thicker and more stable?, Or, less stable?

I tend to think that thinner ice allows more light in, warming the top of the lens, and heat from the mid-waters warms the bottom of the lens making it over-all warmer, lighter, and more stable, but less protected from cyclones.

I still think that the sea ice will continue to diminish as long as the fresh water lens is intact. Then, when a cyclone drives deep mixing, the Arctic will go abruptly blue.

fryingpan136

When the Central Arctic basin eventually becomes mostly free ice, hopefully in the distant future, will it result in a large clockwise gyre about the North Pole? Will the Beaufort Gyre still be strong, or will it get sucked into the polar gyre? Will the increasing polar warmth tend to decrease the gyre strength?

Chris Reynolds

Thanks for the post Alek,

PIOMAS Gice reflects the presence of exported MYI in the East Siberian Sea, for example in 2010 in the following graph. And it seems that since the early 2000s (approx 2002), the previous regime of regular presence of volume from the thickest ice ends. This has ushered in a new regime of 'patchy and sporadic' appearance of large slugs of MYI volume.

https://c2.staticflickr.com/8/7212/27189627866_40e07bd140_o.png

This seems to have happened as both Chukchi and the ESS have begun to exhibit predominant September open water, implying a collapse of summer ice survival rates in these regions.

ESS
https://c2.staticflickr.com/8/7099/27223724265_9ea3f6eebe_o.png

Chukchi
https://c2.staticflickr.com/8/7095/27127120702_0a557c07c3_o.png

Of course a reduction in thick ice volume reduces summer extent in turn.

This means that the mass circulation of the Arctic Ocean ice pack has been interrupted.
https://nsidc.org/cryosphere/seaice/processes/circulation.html
Resulting in the collapse of the Beaufort Gyre Flywheel. The BG flywheel is described by the BG Exploration project.
http://www.whoi.edu/page.do?pid=66596

Susan Anderson

Beautifully done, thank you.

Alekpetty

Thanks very much for the comments so far everyone! It's very inspiring to observe this active sea ice blogging community, and many of the ideas discussed here (and in other blog entries) have definitely given me food for thought.

Just a response to a few comments:

wayne - yes, I should have made it clearer that this mean anticyclonic (clockwise) circulation is the average of very variable ice circulation patterns, including cyclonic (anti-clockwise) drifts on occasion. I've not looked to see if those cyclonic drift patterns (holding the sea ice in the Beaufort) have increased in recent years - as you suggest - but I find the idea of storms contributing to this an interesting one for sure.

Young flat sea ice with more pronounced sails was represented by mechanism 3 in Figure 5. I still expect this to contribute to a reduction in drag compared to the rougher multi-year ice, despite the sails being less weathered. I'm actively looking into this at the moment, however!

D - good point about the importance of repeated wind patterns. And you're right we need more direct observations to understand the freshwater/salt budgets. I was involved with a cruise around the Beaufort Gyre (the same one mentioned by Chris Reynolds) which is trying to do just that. The cruise is limited to late summer, but many of the buoys and the moorings, give us year-round data. More data would be nice though!

Aaron - good point about the stirring. People are actively trying to work out what a younger, thinner sea ice cover might do to momentum transfer into the Arctic Ocean (stirring of the ocean if you like). A new paper came out in the same journal last month by some colleagues of mine (http://onlinelibrary.wiley.com/doi/10.1002/2015JC011186/abstract)which I briefly mentioned in the blog. They concluded that the ice-ocean stress may be reducing (on average across the Arctic) due to the decreased roughness of the younger ice. This was a model study, however, so we still need to figure out how realistic those results were.

There definitely is more heat being absorbed by the upper ocean (thinner ice and more open water) which would make that freshwater lens more stable as it's lighter and thus more buoyant, as you said. The cold layer of Atlantic water below this means the sea ice is somewhat protected from the warmer Pacific Water that resides deeper in the water column. Clearly an idea worth exploring more though.

fryingpan136 - I would say this is a huge unknown! We don't know how much the removal of that insulating 'sea ice lid' will change the Arctic atmosphere/circulation patterns. Clearly there is a lot more heat/moisture being exchanged with the atmosphere now - but I'm not sure exactly what that might do to the location/strength of the BG? Maybe it could become more variable in strength and location?

Chris - I agree with the points about the MYI export variable and melt out increasing in recent years (perhaps's doesn't even matter if it's MYI or FYI, it looks like a lot of that doesn't survive the summer in the Chukchi and ESS as you say). Not sure this will lead to a collapse of the BG flywheel, as that still depends on the wind forcing and ability of the winds to maintain a spun-up ocean, however?


wayne

Thanks Alek,

It is good to have focus on a subject, apparently easy, but deeply complex. Good tidings for your further research!

Chris Reynolds

Alek,

To be clear: I'm not saying the Beaufort High will necessarily collapse or shift, I've not read anything hard and fast about the future prospects in modelling studies. So the circulation will, I expect, continue.

What I am saying is that if the sea ice 'mass' is stripped off the flywheel every summer it no longer provides the 'smoothing' function that keeps summer extent up in Beaufort/Chukchi/East Siberian Sea. Meaning that open water formation efficiency remains high in those regions.

Colorado Bob

Current atmospheric models underestimate the dirtiness of Arctic air

Black carbon aerosols--particles of carbon that rise into the atmosphere when biomass, agricultural waste, and fossil fuels are burned in an incomplete way--are important for understanding climate change, as they absorb sunlight, leading to higher atmospheric temperatures, and can also coat Arctic snow with a darker layer, reducing its reflectivity and leading to increased melting. Unfortunately, current simulation models, which combine global climate models with aerosol transport models, consistently underestimate the amount of these aerosols in the Arctic compared to actual measurements during the spring and winter seasons, making it difficult to accurately assess the impact of these substances on the climate.

Link

Colorado Bob

Sorry Neven , but everyone needs to this -

Sculpture by Isaac Cordal, entitled “Politicians discussing global warming.”

http://d2jv9003bew7ag.cloudfront.net/uploads/Isaac-Cordal-Politicians-Discussing-Global-Warming-from-the-series-Follow-the-leaders-2011-Berlin-Germany-installation-view-photo-credits-Isaac-Cordal.jpg

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