Cyclones and ice-free Arctic

[Richard Rathbone]

Do you disagree with the fact that we can measure quite accurately the energy imbalance between what is coming from the sun and what is being sent back to space? .

Reference? I didn't think this is possible (because the uncertainties swamp the signal) from radiation measurements and was actually done by ocean heat content measurements averaged over many years.

[sedziobs]

Wild, et al (2013) provides a pretty good overview of current energy balance measurements.

http://www.iac.ethz.ch/people/wild/Wild_et_al_ClimDyn_2013.pdf

[Juan C. García]

It is interesting the form in which this small cyclone is bringing heat from Asia to the East Siberian Sea (ESS).
I wonder how much time the ESS and the Beaufort Sea will stay with healthy sea ice.

[Laurent]

Hycom says not very long
http://www7320.nrlssc.navy.mil/GLBhycomcice1-12/navo/arcticictn_nowcast_anim30d.gif

[Vergent]

The ESS gets positively torched with warm, moist air. Each gram of condensation melts almost seven grams of ice.

Verg

[Juan C. García]

The small cyclone is better organized today than yesterday. It has moved away from the Asian coast, but it is still bringing heat to the Arctic.
Most of the Arctic has the air at surface with temperature more than 0ºC.
A crack is appearing on the East Siberian Sea.

[ChrisReynolds]

A tag line from the 2015 season thread.

But Thompson & Rogers 2014, "Swell and sea in the emerging Arctic Ocean"

Although the dynamics are more general than the conventional fetch dependence of
ocean waves, the result is simple: open water distances are the controlling variable for wave heights in the Beaufort Sea (and likely the rest of the Arctic Ocean). Future scenarios for reduced seasonal sea ice cover in the Arctic suggest that larger waves are to be expected and that swells will be more common. Swells carry more energy and have longer attenuation scales within ice [Squire et al., 1995; Squire, 2007] and thus will be more effective at breaking up the remaining ice. It is possible that the increased wave activity will be the feedback mechanism which drives the Arctic system toward an ice-free summer.

Swell - wikipedia.
https://en.wikipedia.org/wiki/Swell_(ocean)

Swell waves often have a long wavelength but this varies due to the size, strength and duration of the weather system responsible for the swell and the size of the water body e.g. wavelengths are rarely more than 150 m in the Mediterranean. Swell wavelength, also, varies from event to event. Occasionally, swells which are longer than 700 m occur as a result of the most severe storms. Swells have a narrower range of frequencies and directions than locally generated wind waves, because swell waves have dispersed from their generation area, have dissipated and therefore lost an amount of randomness, taking on a more defined shape and direction

Large fetch of water, strong winds blowing for a sustained period (some days I suspect) create strong swells.

Squire 2007 is referenced by Thompson & Rogers.
http://web.gps.caltech.edu/~tsai/files/Squire_2007.pdf
This looks at a glance to be the go-to source for ice/swell interactions.

Sorry I don't have the time to read that paper, but it starts off by saying that: "It is well-known that ocean waves can penetrate remarkable distances into ice fields, whether they are composed primarily of continuous sea-ice with imperfections such as cracks, leads or pressure ridges or are a concentration of discrete ice floes and ice cakes that are each free to move back and forth."

My understanding is that while waves (short wavelength high frequency) will be severely attenuated upon hitting the ice edge. Swells with a longer wavelength and lower frequency are not so sverely attenuated and penetrate deeper into the pack. As such the ice pack acts like a low pass filter, the cut off wavelength is probably in the region of several tens of metres (my guesstimate).

[Michael Hauber]

Damage on the back end of the cyclone currently transversing the arctic.  Damage during 2012 at nearly the same date, at the same scale but closer to the pole, and to the east.  The current cyclone is still going and could create some further damage yet.  Prior to the 2012 event the ice was looking comparatively solid, and it was after this point that a significant deterioration began.  It will be interesting to see how we got his year.  Another point about the current low is that it is moving from Russia to Canada, and is not particularly near the pole so its cooling effect is much less.  I think a big part of the cooling effect of lows such as in 2013 and 2014 is not just the cloud, but a persistent circulation near the pole that reduces the amount of warm air mixing into the Arctic from elsewhere.  An off pole low is going to bring in a lot more warm air.

[Jim Hunt]

My understanding is that while waves (short wavelength high frequency) will be severely attenuated upon hitting the ice edge. Swells with a longer wavelength and lower frequency are not so sverely attenuated and penetrate deeper into the pack. As such the ice pack acts like a low pass filter, the cut off wavelength is probably in the region of several tens of metres (my guesstimate).

Following you over from the 2015 melting thread, your understanding is correct, except that surfers (and oceanographers!) tend to talk about "period" rather than wavelength or frequency. They're more relevant to the Antarctic than the Arctic but it seems that  "transoceanic infragravity waves" do the most damage:

http://onlinelibrary.wiley.com/doi/10.1029/2009GL041488/full

Long-period oceanic infragravity (IG) waves (ca. [250, 50] s period) are generated along continental coastlines by nonlinear wave interactions of storm-forced shoreward propagating swell. Seismic observations on the Ross Ice Shelf show that free IG waves generated along the Pacific coast of North America propagate transoceanically to Antarctica, where they induce a much higher amplitude shelf response than ocean swell (ca. [30, 12] s period). Additionally, unlike ocean swell, IG waves are not significantly damped by sea ice, and thus impact the ice shelf throughout the year.

[seaicesailor]

Damage on the back end of the cyclone currently transversing the arctic.  Damage during 2012 at nearly the same date, at the same scale but closer to the pole, and to the east.  The current cyclone is still going and could create some further damage yet.  Prior to the 2012 event the ice was looking comparatively solid, and it was after this point that a significant deterioration began.  It will be interesting to see how we got his year.  Another point about the current low is that it is moving from Russia to Canada, and is not particularly near the pole so its cooling effect is much less.  I think a big part of the cooling effect of lows such as in 2013 and 2014 is not just the cloud, but a persistent circulation near the pole that reduces the amount of warm air mixing into the Arctic from elsewhere.  An off pole low is going to bring in a lot more warm air.

Well, clouds are welcome when it's too hot, especially at this time of the year.
Have a happy solstice day tomorrow you all!

[ChrisReynolds]

Thanks for that Jim, I use the common language in engineering for which I can only apologise.

[ChrisReynolds]

People might find this of interest.
http://dosbat.blogspot.co.uk/2015/06/what-role-did-gac-of-2012-play-in-2012.html

[Juan C. García]

"Did GAC 2012 really just cause 0.15M km^2 of loss? It's not a rigorously scientific position, evidence from a reliable model counters it, but when I look at what happened in terms of anomalies of sea ice extent, it is too much for me to swallow that the Great Arctic Cyclone of 2012 had little impact."
Chris Reynolds: http://dosbat.blogspot.co.uk/2015/06/what-role-did-gac-of-2012-play-in-2012.html

For me it is also very dificult to accept that the 2012 Great Arctic Cyclone only caused 0.15M km2 of SIE lost. It was the first Arctic cyclone that I followed and the way Neven announced it¹ and the way it divided the Arctic Sea Ice in two, was really impresive.

I don´t hope to see another cyclone like that one (seems apocalyptical to me) but I believe that it will happen again  in the following 10 years.

¹ http://neven1.typepad.com/blog/2012/08/cyclone-warning.html

[Michael Hauber]

The comparison between a PIOMAS model run without the cyclone shows that the cyclone caused an additional 450,000 km2 of melt by the 21st of August.  However after this date the model run without the cyclone gains ground, quickly at first, and then slowly right until minimum.  A large amount of ice is separated from the main pack, and melts rapidly during and immediately after the cyclone.  It is about the 21st that the melt of the separated portion is complete.  A large part of the extra melt is found in the model to be due to mixing of ocean heat from the near surface maximum temperature layer.  This results in a significant reduction in the amount of heat available in the near surface maximum layer.  I am guessing that the large gains made by the no-cyclone case after the 21st are due to the fact that the detached portion of ice is still melting out.  By the time this process is complete slow gains continue to be made, and my guess is that this due to the large amounts of heat available in the near surface layer.

The rapid melt due to the GAC 2012 was largely due to a rapid melting of the detached area of weak ice, and due to a rapid mixing of heat from the near surface maximum layer.  If this cyclone had not occured the detached area of ice would have melted regardless , and a lot of the near surface maximum temperature layer heat would have reached the ice anyway.  A lot of the impact of the GAC 2012 was to speed up melt that was going to happen anyway.

Some interesting reading on the near surface temperature maximum layer.  It is roughly 10-20 meters down, is not throughout the Arctic, but is particularly prevalent in the Beuafort Gyre and Candian Basin. It is formed by heat absorbed from above during summer.   Research in 1995 found that the layer disappeared by about October, however current research finds that thinning of the Beaufort Gyre, increased downwelling of water and stratification have allowed some of this layer to survive through winter.

[Jim Hunt]

Some interesting reading on the near surface temperature maximum layer.

Thanks for the link to that paper Michael. It is indeed most interesting, and I hadn't come across it before. In all the circumstances I cannot help but wonder what the addition of >20 s swells to the mix might do!

[Nightvid Cole]

The comparison between a PIOMAS model run without the cyclone shows that the cyclone caused an additional 450,000 km2 of melt by the 21st of August.  However after this date the model run without the cyclone gains ground, quickly at first, and then slowly right until minimum.  A large amount of ice is separated from the main pack, and melts rapidly during and immediately after the cyclone.  It is about the 21st that the melt of the separated portion is complete.  A large part of the extra melt is found in the model to be due to mixing of ocean heat from the near surface maximum temperature layer.  This results in a significant reduction in the amount of heat available in the near surface maximum layer.  I am guessing that the large gains made by the no-cyclone case after the 21st are due to the fact that the detached portion of ice is still melting out.  By the time this process is complete slow gains continue to be made, and my guess is that this due to the large amounts of heat available in the near surface layer.

The rapid melt due to the GAC 2012 was largely due to a rapid melting of the detached area of weak ice, and due to a rapid mixing of heat from the near surface maximum layer.  If this cyclone had not occured the detached area of ice would have melted regardless , and a lot of the near surface maximum temperature layer heat would have reached the ice anyway.  A lot of the impact of the GAC 2012 was to speed up melt that was going to happen anyway.

Some interesting reading on the near surface temperature maximum layer.  It is roughly 10-20 meters down, is not throughout the Arctic, but is particularly prevalent in the Beuafort Gyre and Candian Basin. It is formed by heat absorbed from above during summer.   Research in 1995 found that the layer disappeared by about October, however current research finds that thinning of the Beaufort Gyre, increased downwelling of water and stratification have allowed some of this layer to survive through winter.

Yeah, this is very true. I would argue that a cyclone merely speeds up the melt that is already set to happen. This also aligns with simple physical considerations, that the majority of heat delivered to the upper ocean and ice over the course of the melting season is from direct solar heating, not from cyclones, and it is this energy input which ultimately sets the limit on how much ice can melt each year.

[ChrisReynolds]

"Did GAC 2012 really just cause 0.15M km^2 of loss? It's not a rigorously scientific position, evidence from a reliable model counters it, but when I look at what happened in terms of anomalies of sea ice extent, it is too much for me to swallow that the Great Arctic Cyclone of 2012 had little impact."
Chris Reynolds: http://dosbat.blogspot.co.uk/2015/06/what-role-did-gac-of-2012-play-in-2012.html

For me it is also very dificult to accept that the 2012 Great Arctic Cyclone only caused 0.15M km2 of SIE lost. It was the first Arctic cyclone that I followed and the way Neven announced it¹ and the way it divided the Arctic Sea Ice in two, was really impresive.

I don´t hope to see another cyclone like that one (seems apocalyptical to me) but I believe that it will happen again  in the following 10 years.

¹ http://neven1.typepad.com/blog/2012/08/cyclone-warning.html

I agree Juan.

Michael, Nightvid,

Having read that paper several times I get what you're saying, I'm just stuck on the behaviour of the NSIDC extent anomalies, so don't think the impact was as little as 0.15M km^2.

[Juan C. García]

Thank you for your comments!  Some of them are very interesting.
Just one day left to make your vote!
Have a good day!

[anthropocene]

The comparison between a PIOMAS model run without the cyclone shows that the cyclone caused an additional 450,000 km2 of melt by the 21st of August.  However after this date the model run without the cyclone gains ground, quickly at first, and then slowly right until minimum.  A large amount of ice is separated from the main pack, and melts rapidly during and immediately after the cyclone.  It is about the 21st that the melt of the separated portion is complete.  A large part of the extra melt is found in the model to be due to mixing of ocean heat from the near surface maximum temperature layer.  This results in a significant reduction in the amount of heat available in the near surface maximum layer.  I am guessing that the large gains made by the no-cyclone case after the 21st are due to the fact that the detached portion of ice is still melting out.  By the time this process is complete slow gains continue to be made, and my guess is that this due to the large amounts of heat available in the near surface layer.

The rapid melt due to the GAC 2012 was largely due to a rapid melting of the detached area of weak ice, and due to a rapid mixing of heat from the near surface maximum layer.  If this cyclone had not occured the detached area of ice would have melted regardless , and a lot of the near surface maximum temperature layer heat would have reached the ice anyway.  A lot of the impact of the GAC 2012 was to speed up melt that was going to happen anyway.

Some interesting reading on the near surface temperature maximum layer.  It is roughly 10-20 meters down, is not throughout the Arctic, but is particularly prevalent in the Beuafort Gyre and Candian Basin. It is formed by heat absorbed from above during summer.   Research in 1995 found that the layer disappeared by about October, however current research finds that thinning of the Beaufort Gyre, increased downwelling of water and stratification have allowed some of this layer to survive through winter.

Yeah, this is very true. I would argue that a cyclone merely speeds up the melt that is already set to happen. This also aligns with simple physical considerations, that the majority of heat delivered to the upper ocean and ice over the course of the melting season is from direct solar heating, not from cyclones, and it is this energy input which ultimately sets the limit on how much ice can melt each year.

Most of what you say is most probably correct but I look at it a different way. I haven't done the calculations but I would guess there is more than enough energy in the arctic to melt all the ice. (There was a discussion many moons ago about the inflow of energy through the Bering Strait. iirc the amount of energy in a year alone would melt all the ice).  The issue is getting the energy to the ice in a way such that the ice melts. "cyclone merely speeds up the melt" downplays the impacts. I agree that the ice may have melted anyway but the speed up means that there is more time for other processes to occur (insolation, mixing of the cool 'just melted' water with warmer incoming water,increased contact area of ice to water etc.).  The above would be much clearer if upper ocean and ice were treated independently. In the (simple!) model in my head I treat them as separate systems. The problem then becomes getting the energy in the upper ocean to the ice. Cyclones are very effective at doing this.

[Juan C. García]

The issue is getting the energy to the ice in a way such that the ice melts. "cyclone merely speeds up the melt" downplays the impacts. I agree that the ice may have melted anyway but the speed up means that there is more time for other processes to occur (insolation, mixing of the cool 'just melted' water with warmer incoming water,increased contact area of ice to water etc.).  The above would be much clearer if upper ocean and ice were treated independently. In the (simple!) model in my head I treat them as separate systems. The problem then becomes getting the energy in the upper ocean to the ice. Cyclones are very effective at doing this.

I agree 100%. That's why I asked on this poll for a cyclone in June, July or August.
I believe that a cyclone of the same intensity than the GAC 2012, but in July, will collaborate to establish an ice-free Arctic in September, measure in CT area on a daily basis.