Sea ice, having been rather dull this summer - though it was also briefly interesting in April / May - has suddenly become really quite interesting. Which is odd; the minimum is usually the only time anyone pays attention.
Tamino has a nice post as does Mark Brandon and so does every man and his rabbit. What does that leave me to say? I have to fill in quite a few lines before I get to the bottom of my inset image, after all.
While NH ice is clearly low - indeed, a record for the time of year - it will look much less exciting if it recovers (duh!); just as in summer the April / May excursion became less exciting. MB does a better job, by actually analysing the patterns to some extent, from which you might begin to attribute why it is behaving as it is, which is after all the interesting bit; few people care about the ice for its own sake.
Speaking of which, what about the Antarctic, and by extension the global ice extent? The Antarctic is much more interesting that the Arctic, after all.
Update: Antarctic sea ice 2016: Historic lows by Mark Brandon • November 24, 2016.
The downside of the Antarctic stuff, of course, is that we've spent years explaining why the growth of ice there isn't terribly surprising oh no not at all. Browsing my past, I discover that just in August I was less than convinced by Antarctica’s sea ice said to be vulnerable to sudden retreat? (OTOH I'm happy to say that the DEVM is now looking pretty good even for 8DPSK). However, I don't think that was intended to apply on the interannual timescale. But how time flies! It looks like it was way back in 2012 that I was waving away the increase based on Paul Holland's analysis (wind driven). Eli (bizarrely, IMO, because he's quoting a Curry paper that I didn't like) attributed the increase to snowfall; SKS seem to go for "its complicated" but what all these analyses have in common is that they didn't predict the change, and - at least at the moment - don't provide any explanation for the sudden decrease.
Quite possibly the lack of prediction or explanation is because the answer is "its weather", but in that case its also dull. Vastly more interesting would be if the retreat that "should" be there in the Antarctic but has been "masked" for years has finally kicked in. Only time will tell.
* Silly me to be puzzled. Phil Plait knows exactly what is going on.
Sooner or later as you warm the atm and sea, snow turns not to ice at the edge but to slush. Manabe and Zwally (no e) pretty much nailed that pre-Curry.
[That one is a bit bleedin' obvious and doesn't need nailing :-) -W]
I don't think anyone is keeping the late Andrew Slater's Freezing Degree Days charts up-to-date. Given the DMI N80 warm anomalies and the low extent/area numbers, the implied ice thickness for this spring should be by far the lowest on record - even if temps return to 'normal' for the rest of the winter.
Lebedev gives thickness (cm) = 1.53 * FDD ^ 0.59
Billelo gives thickness (cm) = 1.33 * FDD ^ 0.58
Previous years A comparison of where we are at present compared to previous years would be interesting.
Chris Reynolds did a post on the thickness/growth data with data through 2013. Simple Model of Sea Ice Growth
While "it's complicated" is probably right I think generally sea ice will follow surface temperature. Actual surface datasets don't appear to be very useful, measurements too sparse in that region at this time of year. However, satellite TLT data indicates a big record warm anomaly for October in the Southern Ocean.
To follow up on FDD; just eyeballing the DMI N80 graphs looks like the baseline accumulated FDDs to date from the end of the melt season would be about 1300. This year looks to be approximately 600. Historically we should be a little above 4000 for the winter with recent years slightly below 4000.
Just based on that deficit of 700 FDDs would imply a reduction in thickness of 0.3m. I suspect for N70 the numbers would be even worse since much of that area hasn't even begun to freeze yet.
Crazy Cryosphere: Record Low Sea Ice, An Overheated Arctic, and a Snowbound Eurasia, By: Bob Henson at Weather Underground:
"Experts agree that the laggard sea ice this month around Antarctica is a separate matter from the Arctic, because sea ice in the northern and southern polar regions is produced by two markedly different circulation regimes and geographies. “At NSIDC, we generally frown on the practice of looking at the global sea ice extent,” said Mark Serreze, director of the National Snow and Ice Data Center, “the reason being that ice in the two hemispheres tends to behave rather differently; while Arctic extent shows clear downward trends in all months, the pattern for the Antarctic has been much more complex.” Serreze and several other ice experts I contacted agreed that there was no obvious explanation for why sea ice extent would suddenly dip in unison in both the Arctic and Antarctic when the two processes are typically so uncorrelated. Previous record-warm years didn’t behave this way. Could some previously dormant or absent connection be popping up just now? If so, it’s not an obvious one. NSIDC’s Ted Scambos: “I’d say that to link the two poles with a single causality chain at the seasonal/annual level is probably about a decade of research in the future.”
10 years in the future may be closing the barn door after the horse has already gone on his merry way :)
Horse? Barn? As close as I'll ever get to having a reason to pimp Poco - Rose of Cimarron.
It's not "laggard sea ice" around Antarctica (I had to look the word up: "slow progress and falls behind others".
[For shame! -W]
It's an early spring break out.
Look at the seasonal cycle in Antarctica:
So November historically always has a very rapid rate of change in sea ice. I pointed out on my blog (links on the sea ice post WC refers to above) that this year has seen a lot of open water in the Antarctic / compressed ice edge action. And if you shift the rapid melt region time a week early you will end up with a huge relative change in the Antarctic sea ice.
See the tweet I posted here
I am in the process of sorting out some data to help figure how much earlier the Antarctic break out is.
[Potentially interesting, especially if you can link the breakout to open water and then explain that... -W]
> link the breakout to open water
there's that regression-to-the-mean or is it drunkard's walk thing about variability, in the absence of a trend
"the Antarctic sea ice yearly wintertime maximum extent hit record highs from 2012 to 2014 before returning to average levels in 2015 ..."
Antarctic sea ice extent depends upon the circumAntarctica wind.
Seems like a relevant recent article: http://www.nature.com/news/how-much-longer-can-antarctica-s-hostile-oce…
I am wondering what the optimum configuration of sea ice is for the transfer of mechanical wind and wave energy into water turbulence and heat? By configuration, I mean the ratio of open water to ice, ice size,ice shape, ice density, ice structure, ice strength. Looking at an animation of this year's melting Arctic ice, it sure looks like the ice has much more motion, reflecting more surface turbulence, just before it rapidly succumbs to the melting process. That may, of course simply be an artifact of the fact that just before the ice disappears, it is presumably at its thinnest point, and therefore is more susceptible to and more illustrative of the motion of the wind. Or, perhaps at some points in the melting or refreezing process, conditions are optimal for transferring mechanical energy to the sea/ice matrix and thus making one process or the other more favorable.
If there is anything to this speculation, perhaps one can expect a precipitous diminution of ice at times when one might otherwise expect normal refreezing to be taking place.
Know what I mean Vern?
[Transfer of momentum from air to water - at least in the version that I used to know, which is in the climate models - is simply a matter of the wind speed and the surface roughness; and the latter, of course, depends on the proportion of water and ice and perhaps the characteristics of the ice. Well, rather than me try to remember it, I could point you at, e.g., http://journals.co-action.net/index.php/tellusa/article/viewFile/14505/… -W]
As surfers and jetty designers can confirm, the power density of the fluid sea surface approximates the fourth power of the wave amplitude, - 2 meter waves are 16 times more powerful than 1m .
So the Joule thermal equivalent is large in storm conditions ( waves > 5m) but small in a mild breeze ( waves < 50 cm )
My eyeballs were a little off. I've downloaded and charted the DMI N80 data and converted it to FDDs. The result can be seen in this comment at the Arctic Sea Ice Blog Forum
Thru Nov 19 we should be, per 1958-2002 climo, at 1100 FDDs. We're at 500 (-600 on the graph). We're also significantly lower than any of the previous ten years.
Over the full season climo accumulated FDDs is about 5450. The 2015-6 freeze season was the lowest on record at about 4300.
Given the non-linear relationship between ice thickness growth and FDDs, temperatures returning to anywhere near normal would make the current deficit of minor interest -- but like so many arctic metrics we're in unknown territory. Beware of dragons -- and black swans :)
Must be playing heck with all the old plans for hiding the second-strike nuclear submarines under the ice ...
So, THAT is why those last “little” pieces of ice appear to dance around like spit on a hot griddle just before they disappear... turbulence from second strike subs furiously trying to hide under them! (Note to tin foil hatters.... I am just joking.) Although I suspect that the real reason is that the smaller pieces of ice are just thinner and have less mass, so their surface area to mass ratio optimizes their susceptibility to wind effects... and also increases the amount of sea water that they are exposed to and to which they can transfer heat to as they skittles about in the wind. Or maybe it was just a very warm and/or very windy and turbulent time period when they took that particular sequence of photos.
Oh and thanks to William and Russell for the very helpful citation and basic knowledge. Knowing some basic terminology sure helps the search process!
> why those last “little” pieces of ice appear to dance around
I think you're seeing pixels rather than little pieces of ice, at that scale -- trying to show that, what, 15 percent ice cover when the pieces of ice are too small and not optically resolved.
Oh my have you been listening to Alan Parsons?
[Only when not listening to Rio :-) -W]
Not to expose my ignorance, but surely you don't mean Duran Duran?
[But of course! https://www.youtube.com/watch?v=KcIUbKkYah8 -W]
Zut alors! I hope you have Toto IV on your carousel too.
Steve & Kevin
A propose of wave energy & black swans, I should have mentioned that the ocean wave height spectrum features one 3x mean height Rogue Wave per few thousand 2x mean height big waves.
absent slush ice to raise the effective viscosity and damp them, the rogues can chew up the edge ice something fierce.
As if we needed annother reason to sail in the tropics.
Updated version of the global area graph is kept at
not all that much better looking.
[What do you mean not much better? That clearly shows that in the second half of November it usually declines steeply, but this year it increased slightly :-) -W]
>"[But [PIOMAS] will either be more interesting in a month, or less -W]"
"Gridded thickness data has been updated. Volume data not yet. From the thickness data I estimate volume on day 335 is 9.515 [1000 km3], about 700 km3 below 2012, lowest for the day."
Still doesn't look much better.
Is this what hitting a tipping point would look like?
Which doesn't mean we have actually hit a tipping point, of course.
"Accumulated Freezing Degree Days N80 thru Dec 29, 2016:
Implied new ice thickness to date:
Climo: 1.412 m
2016: 0.973 m
Climo: 1.137 m
2016: 0.788 m"
Looking a long way from the pack. FDD anomaly almost as large as actual.
Rather worrying for 2017?