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Absolutely fantastic post, Neven. And well researched too.

Just a few points to make that may be salient to the overall discussion:

Cold core storms, especially powerful ones, tend to lower the atmospheric temperatures near their center and under their circulation by about 10-15 degrees (F).

In the earlier research, it seemed conclusive that these Arctic storms were a powerful negative feedback (under a regime of cooler temperatures and thicker ice) even during summer-time. And this is probably due to their cold nature as well as to their less decisive impacts on thicker ice.

GAC 2012, as noted in A. Kriegsmann and B. Brümmer's paper, however, raised the potential that these storms can be a positive feedback.

With rising ocean and atmospheric temperatures and thinner ice in the Arctic, the scales seem to be tipping moreso toward the positive feedback storm, despite the fact that storms lead to cooler, cloudier conditions. So, if ocean and atmospheric temperatures keep rising in the Arctic, then we should see more storms like GAC 2012 that result in ice melt.

In the case of PAC 2013, we have moderately lower than average atmospheric temperatures, but large fragmentation (and I would say, basal melt) in the regions impacted. Whether or not it becomes a positive feedback, overall, (and is unprecedented, as I have possibly, prematurely asserted) will probably be ruled by end season melt.

PAC 2013 looks to finally be finished by around Thursday or Friday of this week. So we'll get a chance to see what kind of an impact new conditions have on all that fragmented ice.

Best to all.

Account Deleted

This is an impressive review, Neven! Your prestige is very well fundamented.

I just wanted to ask, you may know, if there's a simple map somewhere that shows if it's gonna be sunny here, cloudy there ..., a prediction map just like the one the tv meteo guy shows, but for the Arctic. Doesn't sound very serious I guess...


Excellent post!

Within the last few days, the CT map has gone from showing mostly purple over Siberia to looking outright gangrenous.

I think the mechanical energy provided by PAC-13 totally chewed the ice up, and any reduction in insolation was ineffective at preserving the already weak ice.

I don't have a number for the other thread, but I'm throwing my prediction down: we're going to break the record and it's going to be ugly.

Protege Cuajimalpa

Congratulations, Neven. Excelent post and thank you for al this work.

Remko Kampen

Esteemed climate scientist (and meteorologist) :)

Fig. 3 really struck me. Looking at the Atlantic regime particularly I read therein that zonal years are better for the ice than are 'blocked' years. This was actually known in small circles by the 1980's, but I've not seen real confirmation like this before.
What was not well known back then was the role of cloud cover as provide by cyclones. But blocking events obviously send batches of heat far into the Arctic, which melt ice or inhibit freezing.

This is especially interesting today as blocking events seem to become more common, more vigourous and more persistent. But then we might be looking at another example of Arctic Amplification.

I just wanted to ask, you may know, if there's a simple map somewhere that shows if it's gonna be sunny here, cloudy there ..., a prediction map just like the one the tv meteo guy shows, but for the Arctic. Doesn't sound very serious I guess...

Ulises, I usually look at the ECMWF weather forecast on Wetterzentrale (click on N.-Hem. and then the days - 24, 48, 72, etc - next to 500 hPa, SLP). The position of the highs and lows tell me approximately where it will be sunny or cloudy, and which way the winds are pushing the ice.

Check out my ASI update videos, where I will regularly talk about the things I do to watch the ice.

Chris Reynolds

Very good post, enjoyed reading it.


Do not under rate yourself. You are far more knowledgeable then some who like to show off the degrees.
Seeing the historical highs in Alaska and other areas around the north, does this not show how much pulling in of hot air the cyclone is creating? Granted the temps were for only short times but that is a killer for any snow in the area and can also very negatively impact the permafrost I should think.
Having a major storm disrupting weather patterns this early in the season and add into that the weakened jet stream could this not create conditions where hot air continues to flow into the Arctic and with the massive fragmentation in the centre open up avenues for currents from the south?

Aaron Lewis

Global warming has been acting on the Arctic for a long time. The difference between the cold, dry environment of an Arctic cyclone in 1920 [320 ppmv CO2] and the almost as cold, almost as dry environment of an Arctic cyclone in 1960 [350 ppmv CO2] was small, but real. However, by 2012 [397 ppmv CO2], an Arctic cyclone was in a much warmer, much wetter environment. GAC-2012 was a different kind of storm. Serreze & Barrett, 2008) describe an intermediate form of Arctic storm in intermediate conditions.

To rank Arctic cyclones strictly on the basis of central pressure is like comparing desert dust devils to real tornadoes, and tornadoes to hurricanes. These are three different phenomenon that occur in three different environments. The Arctic "then" is not the Arctic "now". The Arctic now is warmer, wetter, and produces different kinds of atmospheric phenomena.

GAC-2012 and PAC-2013 are different from the Arctic cyclones from before 2005, when the Arctic was drier and colder. If you remember, more than a year ago I predicted that in 2013, a large Arctic cyclone would fracture the ice this year. One could not make such predictions about traditional Arctic cyclones. They were too small and localized to cause wide spread ice fracturing and movement. They were fueled by one lobe of the 500 mb jet stream coming across Siberia.

Today's, Arctic cyclones suck in latent heat from both the North Atlantic and the Pacific (across Alaska) at the same time. This is a sea change from the kind of storms that Serreze & Barrett,(2008) address.

Further, I predict that PAC-2014 will be larger and more stable. GAC/PAC are more closely related to polar vortex and global circulation phenomena than to the traditional Arctic cyclones.

In the past, latent heat from the oceans had a more zonal flow at the southern edge of the Arctic. Now, that latent heat from the North Pacific and North Atlantic is transitioning to a more meridional flow into the Arctic. I expect more persistent Arctic cyclones are a part of what is driving increased meridional atmospheric circulation. Ultimately, meridional atmospheric circulation will drive additional meridional ocean circulation. This additional meridional ocean circulation will carry a good deal of heat into the Arctic.

Such enhanced ocean circulation is the pathway to a year-round, sea ice free Arctic. I suggest that GAC-2012 and PAC-2013 mark the trail head to a sea ice free Arctic.

Kevin McKinney

Thanks for a very nice summary, Neven. Some of these questions were bothering me, too, but you did something about it!

Well-done, and much appreciated.


".. heavy ice losses will become visible as soon as the weather switches (or even if the weather doesn't switch)"

Fantastic post.

The clouds have just lifted above the Bering Strait as far as microwave is concerned -- if that reddish brown really represents melt ponds, an incredible development.

Will we see this region of melt link up to the Svalbard to New Siberian Island fracture zone?

Attribution of either phenomenon to the recent cyclone is problematic as we don't know how things would have looked without it.

 photo 18JunemeltPonds2_zps8207fe8a.gif


Saw this article today - where will this heat be travelling after Alaska?



Um. Wrangle island wind speed at 150 knots? Screaming temperature differential or erroneous data?

I've saved the Uni-koeln image. Will post tomorrow.

John Christensen

Another great entry and summary Neven!

Some comments above compare GAC12 and PAC13, but this is not supported by the findings of Screen, Simmonds and Keay above, where they conclude that increased cyclonic activity in late spring/early summer (May-July) tends to favor a higher SIA by September. Therefore, a late summer cyclone such as GAC12 is a different animal and would need to be so, since it impacts less compact ice and moves it across heated surface water.
As I indicated on 5/29 on the ASI I entry, I would favor a low in the early summer for these reasons; increased cloud cover/lower temperatures around solstice, and then quiet weather/open skies for late summer/early fall, where the sun has lowered significantly already.
However, the stage is different this year, so it is possible that old rules do not apply anymore.


Nicely done, reads like a thesis proposal. The recent cyclone has led to quite cloudy weather over nw Greenland, but lots of clear weather images from NE Greenland. Zachariae Ice Stream being one outlet with nice recent imagery including from Junea 17th, explanation at link above.


More fragmented ice than ever all over the Artic, partly because of the cyclone:

Thru the mostly clear sky and albedo flip warming and melting will now speed up. It will be interesting to see how fast.


Here is that Bering Strait region again without the clouds, this time on Modis 7-2-1 for RGB, 645-853-2130 nm. This is a new product that I am only seeing on Nasa Worldview alpha after changing projection and other defaults. It is a much more successful combination of channels than 3-6-7 orange and indeed more useful than their visible. Note that it largely confirms Jaxa color and may even distinguish melt ponds from open water.

Note Neven is doing very well in the search game, ahead of wikipedia and perhaps sneaking up on NSIDC.

 photo 721Bering19Jun13_zpsaf81324f.jpg

Craig Dillon

Excellent research and post. Thanks.

R. Gates

Excellent post as usual Neven. It will indeed be interesting to watch how the PAC-2013 influences the rest of the summer melt. A few things to point out. These cyclones do not actually bring cold air to the Arctic. but rather, they lead to conditions whereby longwave is being transfered from the atmosphere to the ice, thereby cooling the atmosphere continually above where the cyclone and associated clouds are. The opening up of the ice to open water during the cyclone will be important later on once the cyclone is gone and allowing for more shortwave to penetrate into the open water. Far more important for the melt of the ice is the longwave associated with the greater cloud cover.

I would reference this research:


And this quote from the abstract:

"Moreover, we also show that the anomaly in longwave radiation is due to an anomaly in clouds. Simply put, more clouds give more net longwave radiation to the surface which enhances the melt."

The cyclones in summer actually advect more energy from lower latitudes to the Arctic, but they appear to bring "colder air" because the longwave from the clouds is being absorbed by the ice below, therby keeping a persistent area of cold centered where the cyclone is.

In general, I wonder if we might end up seeing a one-two-three punch from these summer cyclones as the ice thins:

1) More long-wave is transferred from cloud to sea ice during the cyclone. (cooling the atmosphere, but leaving more vulnerable ice)
2) More short wave can penetrate to the open water left after the cyclone ends
3) More melting of the sea ice from below can occur as the warmer water can occur at increasingly higher latitudes and later into the season.

Finally, I do not see the summer cyclones as even possibly being negative feedbacks, but rather quite the opposite, as even more energy is being advected to the polar region. More energy can only mean the even quicker ultimate destruction of the ice, even if during period of the cyclone we might get some interesting divergences happening.


From the summary:

"We find a clear correlation between negative (positive) sea-ice extent anomalies in September and positive (negative) anomalies in net longwave radiation the preceding March-through-May"

I'd be curious to see what the findings are for June and July. Sent a request for the discussion.

Lynn Shwadchuck

Wow, wonderful sleuthing, Neven. I agree with the few people who have said in response to your post that only positive feedbacks seem likely.


Looking at the most recent pressure map from DMI, we see PAC forming a trough with a new low in the Central Arctic. ECMWF shows lows in or near the CAB all through the model runs.

So it looks like the dance continues...

Oh, and fractures now from Wrangle Island all the way to Svalbard.

@ R Gates

Thanks for the report. Had posted a brief response on it, but seems to have been eaten by the spam filter.

Did you see the new Greenland report? Found a blocking pattern-induced heat dome that formed low clouds which enhanced melt for 2012. Wayne had also posted on the effect of clouds earlier.



Excellent researching & summing up, Neven.
I should have been commissioning you to write my Climate Literacy course assignment for me! Whayaya know about NZ's glaciers responding to climate changes.....
darn, I see you're going to be away.

William Hughes-Games

I wonder if the opposite could also happen. Think to the future when much more of the Arctic Ocean is ice free for longer periods in the summer and hence has accumulated much more heat. Toward fall, as the incident radiation on the surrounding land decreases, at some point, snow falls and doesn't melt. The land cools off very rapidly since only the top foot or so is involved. Now you have a very cool area surrounding the ocean, with the air above the land cooling off and falling. Over the ocean, by contrast, the heat accumulated in the summer is warming the air and putting much water vapor into the air. You have a positive AO from the surrounding land to the ocean and Coriolis starts this body of air rotating counter clockwise. It would seem to be a formula for some very strong cyclones in late summer and fall. Since in an anticlockwise rotating system, Coriolis is away-from-the-centre, if the ocean is spun counterclockwise by the storm, ice and fresh water should be pushed toward the exits from the Arctic ocean, making the surface water shallower and bringing the deep, salty, slightly warmer Atlantic water closer to the surface. The longer, higher waves from such storms will then be able to mix these layers more effectively, further pushing the Arctic toward an ice free condition.

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