On persistent cyclones

As the persistent Arctic cyclone - or PAC-2013 - of the past couple of weeks winds down, I want to discuss what I've found on the subject in a couple of research papers. But first want to refer to two excellent blog posts from last week doing just that, on the Robertscribbler blog and FishOutofWater's blog on Daily Kos.

This animation of DMI SLP maps shows the birth and demise of PAC-2013:

Perhaps I should say near-demise, but the weather forecast says it's basically over for this cyclone. Of course, other cyclones come into play in other parts of the Arctic, but it's not the PAC-2013 anymore. After approximately 25 days of wandering around, weakening and re-strengthening to a pretty powerful cyclone at times, churning ice, keeping the Arctic cold, we've witnessed another remarkable cyclone in less than 1 year's time.

There are a couple of questions that have been on my mind ever since the cyclone started to show itself persistent:

1. Is PAC-2013 unprecedented?
2. Is it somehow caused by the progressive loss of Arctic sea ice?
3. If so, will we see these PACs more often?
4. What will the effect on the sea ice be, short-term and long-term?

To answer some of these questions I did a search on Google Scholar with summer arctic cyclone as search words. Because the Arctic is changing so fast, I was mostly interested in recent research, but I remembered there was one paper from 2008 that I read last year during GAC-2012, that also has interesting things to say about Arctic summer cyclones. So, I'll start off with that one and quote the most interesting parts.

The Summer Cyclone Maximum over the Central Arctic Ocean
Mark C. Serreze and Andrew P. Barrett, 2008, Journal of Climate

From the abstract:

A fascinating feature of the northern high-latitude circulation is a prominent summer maximum in cyclone activity over the Arctic Ocean, centered near the North Pole in the long-term mean. This pattern is associated with the influx of lows generated over the Eurasian continent and cyclogenesis over the Arctic Ocean itself. Its seasonal onset is linked to the following: an eastward shift in the Urals trough, migration of the 500-hPa vortex core to near the pole, and development of a separate region of high-latitude baroclinicity. The latter two features are consistent with differential atmospheric heating between the Arctic Ocean and snow-free land. Variability in the strength of the cyclone pattern can be broadly linked to the phase of the summer northern annular mode [also known as Arctic Oscillation, N.].

Figure 2 from the paper shows the annual cycle of number of cyclone centers within a specified region of the central Arctic Ocean in the 1958–2005 period:

There's now plenty of snow-free land available in late spring and early summer (see these long-term bar graphs for May and June), and this almost certainly played a role in last year's GAC and this year's PAC. The thing I learned from this paper was the part about how cyclones get born in eastern Eurasia, then move eastwards and northwards and either make it to the Arctic or not, where they either move over to the central Arctic or feed an existing cyclone there. That's something I'm on the look-out for nowadays when checking weather forecast maps.

Here's what they say about that further in the paper:

At least some of the systems generated over eastern Eurasia migrate into the central Arctic Ocean and contribute to the summer cyclone maximum, while those formed over northern Alaska instead tend to track eastward or southeastward into the Canadian Arctic Archipelago (Serreze et al. 2001).

(...)

We show that while the summer pattern is, in part, associated with the influx of lows generated along northeastern Eurasia, where the Arctic frontal zone is especially well expressed, the broader picture involves an eastward shift in the Urals trough and migration of the 500-hPa vortex core to near the pole, associated with the influx of systems generated along a wide swath of the Eurasian continent, augmented by cyclogenesis within the Arctic Ocean itself.

Serreze et al. also describe their case study of June 1989:

At 500 hPa, a closed low persisted over the Arctic Ocean for the entire month, meandering about the region. On a daily basis, it was typically highly asymmetric, and the surface lows developed and deepened ahead of the troughs.

Another paper by Tanaka et al. (2012, PDF) also has two examples of persistent cyclones:

The cyclone in Case 1 was strongest at 12Z on 19 July 2006 and persisted for 28-days staying in the middle of Arctic Ocean.

(...)

The cyclone in Case 3 was strongest at 06Z on 22 June 2008 and persisted for 20 days. These cyclones move rather randomly in direction for sufficiently longer period, indicating the characteristics of the arctic cyclone, which is distinctly different from the movement of the mid-latitude cyclones or tropical cyclones.

This answers question 1 above: PAC-2013 isn't unprecedented.

But the conclusion of Serreze and Barrett (2008) echoes questions 2 and 3:

While there have been no trends in the strength or persistence of the summer cyclone pattern over the period of 1958–2005, it is natural to speculate on its future behavior. Climate models are in near-universal agreement that Arctic warming in response to greenhouse gas loading will be especially strong. Results from the present study suggest that, at least in part, the summer cyclone pattern owes its existence to differential atmospheric heating between the Arctic Ocean and snowfree land. If patterns of differential heating change substantially, such as through earlier springtime loss of snow cover over land, or through changes in the presently strong summer net surface heat flux over the Arctic Ocean as the sea ice cover disappears, this may invoke changes in the summer circulation.

It takes a while for changes to become apparent statistically, but we might well have entered the period of changes some time back.

The following paper discusses the effects of cyclonic activity:

Dramatic interannual changes of perennial Arctic sea ice linked to abnormal summer storm activity
James A. Screen, Ian Simmonds and Kevin Keay, 2011, Journal of Geophysical Research

From the introduction:

The perennial (September) Arctic sea ice cover exhibits large interannual variability, with changes of over a million square kilometers from one year to the next. Here we explore the role of changes in Arctic cyclone activity, and related factors, in driving these pronounced year‐to‐year changes in perennial sea ice cover. Strong relationships are revealed between the September sea ice changes and the number of cyclones in the preceding late spring and early summer. In particular, fewer cyclones over the central Arctic Ocean during the months of May, June, and July appear to favor a low sea ice area at the end of the melt season. Years with large losses of sea ice are characterized by abnormal cyclone distributions and tracks: they lack the normal maximum in cyclone activity over the central Arctic Ocean, and cyclones that track from Eurasia into the central Arctic are largely absent.

Figure 3 shows the difference in total cyclones for ice loss years and ice gain years (in relation to the preceding melting season) during May, June and July:

I can confirm what the bolded text says, as it's something I learned quite quickly in the preceding melting seasons that were covered here on the Arctic Sea Ice Blog. But like I said last year: "I feel as if all I've learned in the past two years has already turned obsolete". This quote, BTW, was used by The Guardian columnist George Monbiot, where he actually called me a climate scientist.:-P

I'm not sure if the relation still holds true today (see question 4 above), as the ice is thinner than it has been probably since the Holocene Climatic Optimum. As we saw last year, weather conditions that weren't conducive to ice cover decrease didn't really matter all that much for the rate of decrease, and well before GAC-2012 struck, the trend lines on extent and area graphs were already in record territory, or headed there. This could be due to the good start to the melting season 2012 had, but the overall thinness of the sea ice definitely played a role as well.

Screen et al. say as much in the conclusion:

Our results also suggest that a strengthening of the central Arctic cyclone maximum during MJJ helps preserve the ice cover and leads to anomalously high September sea ice. However, the relationship does not appear to be entirely linear with a clearer association between low cyclone activity and reduced sea ice than between high cyclone activity and increased sea ice.

There is no doubt that dominating high pressure systems guarantee big ice losses, as they keep skies clear (leading to high insolation) and kick the Beaufort Gyre into action, leading to ice pack compaction and increased ice transport towards Fram Strait. It could very well be that the question whether increased cyclonic activity during late spring and early summer leads to a higher minimum or not, depends on the overall thickness and state of the ice pack. Does it slow the car down or does it make it go in reverse?

Another interesting tidbit looking forward from the conclusion:

We found no significant trends in late spring or summer Arctic cyclone frequency over the period 1979–2009, and neither did Simmonds et al. [2008] over a similar period but with different data sets. Serreze and Barrett [2008] also found no significant trend in summer cyclone occurrence over the central Arctic during the longer period 1958–2005. Therefore, it seems unlikely that multidecadal changes in cyclone activity are a primary cause of the observed decline in perennial sea ice. However, this does not imply that future changes in Arctic storm activity will be peripheral to determining when, if as projected, a seasonally ice‐free Arctic Ocean is realized.

Again, we touch upon question 4: What will the effect of (increased) cyclone activity on the sea ice be, short-term and long-term?

For that we turn to a recent paper that looks into the effects of cyclones:

Cyclone impact on sea ice in the central Arctic Ocean
A. Kriegsmann and B. Brümmer, 2013, The Cryosphere Discuss.

From the abstract:

In general, cyclones reduce the ice concentration on the order of a few percent increasing towards the cyclone centre. This is confirmed by independent AMSR-E satellite data. The reduction increases with cyclone intensity and is most pronounced in summer and on the Siberian side of the Arctic Ocean. For the Arctic ice cover the impact of cyclones has climatologic consequences. In winter, the cyclone-induced openings refreeze so that the ice mass is increased. In summer, the openings remain open and the ice melt is accelerated via the positive albedo feedback. Strong summer storms on the Siberian side of the Arctic Ocean may have been important reasons for the recent ice extent minima in 2007 and 2012.

Figure 1 shows the study area and spatial and seasonal distribution of the cyclone detections (dots) for the period 2006–2008 (click for a larger version):

This is a very interesting, though slightly technical, research paper. 7987 cyclones in the 2006-2008 period are analyzed with the help of a model, and categorized according to intensity, season and region. Here are the interesting tidbits:

The dynamic impact of cyclones has substantial impacts on the sea ice cover. The strong, inhomogeneous wind field deforms the ice cover and causes cracks, leads and polynias. The thermodynamic effect of these openings is different in winter and summer. In winter, the openings are the places with the largest heat fluxes from the ocean to the atmosphere. The openings refreeze so that the heat fluxes decrease with time and salt is released from the newly formed ice to the ocean. In summer, refreezing does not occur, so that almost all downwelling shortwave radiation is absorbed. This leads to a local warming of the uppermost ocean layer and promotes further ice melt.

(...)

On average, each cyclone has 5.05 detections, i.e. a lifetime of about 30 h [in the 2006-2008 period, N.].

(...)

On average, the wind is weaker in summer than in autumn and winter. However, the differences are not large: the maximum is 6.2ms−1 in summer and 6.8ms−1 in winter.

(...)

The general impact of cyclones on sea ice concentration consists of a 24 h-reduction within the radius of the cyclone in all seasons (Fig. 10). The reduction is most pronounced in spring and summer. In the core of the cyclone the ice concentration is reduced within 24 h by 0.92% in winter, 1.67% in spring, 2.53% in summer and 1.17% in autumn.

(...)

The seasonal difference in the duration of a cyclone’s impact can have extensive climatological consequences. A lot of studies were done on the change of cyclone activities. Some of them found an increase of the number of cyclones in the Arctic (e.g. Sepp and Jaagus, 2011). Zhang et al. (2004) found, that the number of summer cyclones increases. If the number of cyclones in the summer increases, than the melting of sea ice can be accelerated.

And from the conclusion:

On the short time scale of a passing cyclone, freezing and melting play a minor role in the change of ice concentration. Thus, the cyclone-induced reduction of ice concentration is almost solely due to ice sheet deformation. This means that there is no loss of ice mass but that the ice is ridged. Thus, the cyclone causes more thick ice. The following processes, freezing and melting, have different longer-term or even climatologic consequences in winter and summer. In winter, the heat flux between ocean and atmosphere over the cyclone-induced open water areas is increased for a few days. This heats and moistens the shallow Arctic boundary layer. At the same time the freezing of the open water areas leads to the formation of new sea ice, so that a further important impact of the wintertime cyclones is an increase of the Arctic ice mass. In summer, the cyclone-induced reduction of sea ice concentration is largest and the open water areas remain open. This summertime impact is expected to be especially large in areas with thinner ice as, e.g. on the Siberian side and in the marginal ice areas of the Arctic Ocean. Strong summer storms in those areas can lead to increased exceptional reduction of the sea ice concentration. The strong summer cyclone between 4 and 8 August 2012 is believed to be one reason for the following record ice extent minimum in September 2012 (e.g. Beitsch, 2012).

One thing we know for sure and that's that there's a lot of first-year ice in the Arctic right now. Let's return to our 4 questions at the top of the blog post, with summarized answers:

1. Is PAC-2013 unprecedented?

No, but its effect on the sea ice might be. Previous PACs had substantially more ice below them to withstand the pulling forces of the cyclone.

2. Is it somehow caused by the progressive loss of Arctic sea ice?

It seems that decreased Arctic sea ice area and volume, combined with a radical decrease in spring and summer snow cover on the Northern Hemisphere, play a role in cyclogenesis (love that word) and cyclonic behaviour.

3. If so, will we see these PACs more often?

Could be, it's too early to tell. We had GAC-2012 last year, and PAC-2013 this year. We'll see what happens next. Or to paraphrase the historic quote by Dr Jennifer Francis: How could we not?

4. What will the effect on the sea ice be, short-term and long-term?

We still have to find out what exactly the short-term effect of PAC-2013 will be. Either the clouds and cold that the cyclone brought in, offset the churning and dispersing of the ice pack, and equalling last year's record smashing melting season is virtually impossible. Or the cyclone pre-conditioned the ice pack by causing many holes to show up from Svalbard to the New Siberian Islands, and heavy ice losses will become visible as soon as the weather switches (or even if the weather doesn't switch, like we saw last year in July).

For the long-term: If this cyclonic activity early in the melting season helps conserve the ice, even though it's thinner, AND cyclonic activity increases because of Arctic sea ice and NH snow cover loss, then we have a serious negative feedback that could postpone the occurrence of a sea ice-free Arctic.

If it this isn't the case, we have a slightly better set of conditions compared to anti-cyclonic dominance (high pressure systems with clear skies and Beaufort Gyre), but it doesn't really matter in the longer term as it doesn't help the ice pack recover.

This year might give us some clues. And so we learn...

Comments

[Robertscribbler.wordpress.com]

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...

[Rlkittiwake]

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.

[Neven]

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.

[LRC]

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.

[A-Team]

".. 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.

[Kate]

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

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/06/18/record-shattering-heat-bakes-alaska/

[Robertscribbler.wordpress.com]

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.

[Glacierchange.wordpress.com]

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.

[Lennartvdl]

More fragmented ice than ever all over the Artic, partly because of the cyclone:
http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic.2013169.terra.4km

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

[A-Team]

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.

[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:

http://fallmeeting.agu.org/2012/eposters/eposter/a11k-0196/

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.

[Robertscribbler.wordpress.com]

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.

[Robertscribbler.wordpress.com]

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.

http://onlinelibrary.wiley.com/doi/10.1002/joc.3743/abstract

[Clare]

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.
C

[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.