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Artful Dodger

Hi folks,

Toward the end of the melt season, melt ponds cover up to 50% of the sea ice area, decreasing the value of the surface albedo by up to 20%. Total melt is proportional to total solar energy absorbed, which is the time integral of sea ice albedo. Hence, earlier melt ponds, more melt.

Things aren't just black and white, not in the Arctic, and not with our energy choices. It's time for "Less Denial, More Action" by reducing our reliance on fossil fools.

Cheers,
Lodger

Artful Dodger

Neven wrote:

"Which goes to show how incredibly handy it would be to have near real-time melt pond cover fraction data at our disposal, which we could then compare to data from the last 5-6 years."

Our blog statistic "Cryosphere today Per Ijis Extent" (CAPIE) summarizes in melt pond fraction in numerical terms. Understand that CT ice area is derived with the ARTISAN sea ice algorithm, which is tuned to classify melt ponds as open water. On the other hand ( or denominator ;), IJIS extent uses an algorithm which classifies melt ponds as sea ice. Thus CAPIE also includes a measure of the total fraction of melt ponds.

Indeed, blog all-star Wipneus may be ideally situated to create the exact metric we'd be interested in seeing. With his access to daily IJIS AMSR2 data, by processing the data twice (once with each alternative algorithm), we would see JUST the melt pond fraction. And the geographic distribution of those melt ponds could be plotted on Wipneus' signature graphs and animations. :^)

Voor niets gaat de zon op!

Cheers,
Lodger

Micheltsamados

Thanks Neven,

great summary of our work.

Have a also a look at another piece on this at http://www.micheltsamados.co.uk/september/

Hopefully we will have some interesting feedback and useful discussions about this at EGU2014 next week.

Three of the authors Daniel Feltham, Daniela Flocco and me will be there. Sadly David Schroeder (the first author) will not make it this year.

Cheers,
Michel

Neven
Have a also a look at another piece on this

That's great. In fact, the rest of your website is also great. I've added links to the blog post.

Like you say, incorporating this stuff and ice drift into models, should really help improve forecasts. Ocean heat flux would be nice too, but I think that's the hardest thing to observe, and thus model.

Hopefully we will have some interesting feedback and useful discussions about this at EGU2014 next week.

Darn it, darn it, darn it! I already felt bad about not being able to go to EGU (even though I don't live that far from Vienna), now I feel even worse. :-(

If I would be there, I'd ask the following:

1)How difficult is it to create near real-time melt pond cover fraction data that can be compared to other melting seasons in the 2007-2013 period? May is just 5 days away. Easy, right?
2) Will you do another prediction this year, and make it known in June (preferably through the Arctic Sea Ice Blog ;-= )?

Kevin O'Neill

Neven asks - "How difficult is it to create near real-time melt pond cover fraction data that can be compared to other melting seasons in the 2007-2013 period?"

We may not be that far away. One of the papers currently in discussion at The Cryosphere Discuss is Sea ice melt pond fraction estimation from dual-polarisation C-band SAR – Part 1: In situ observations (R. K. Scharien, J. Landy, and D. G. Barber).

[Corrected the link, N.]

sofouuk

as Steve Bloom says on the other thread, the amount of melt ponding is obviously a reflection of spring weather, but what is the relative contribution of temperature and insolation? can the amount of melt ponding be predicted from general weather conditions (or even forecasts)?

Neven

Thanks a lot, Kevin! That's a completely different method, it seems. Hopefully something comes out of all this research that allows us to better assess the start of the melting season.

Our blog statistic "Cryosphere today Per Ijis Extent" (CAPIE) summarizes in melt pond fraction in numerical terms. Understand that CT ice area is derived with the ARTISAN sea ice algorithm, which is tuned to classify melt ponds as open water. On the other hand ( or denominator ;), IJIS extent uses an algorithm which classifies melt ponds as sea ice. Thus CAPIE also includes a measure of the total fraction of melt ponds.

That's true, but a direct measurement would be better, as CAPIE is also influenced by compactness of the ice pack.

Kevin McKinney

Exciting! It would be great if seasonal-scale constraints could be arrived at...

wayne

Melt ponds should mirror the ice bottom topography. But the larger reason for their appearance has something to do with complex thermal interactions luckily made simple by observing the horizon. I deal with what may be ice models Achilles' heel, the very reason why they fail might have something to do with the remarkable phenomena of ice cooling faster than air:

http://eh2r.blogspot.ca/

A simple example may help reveal the error, of which thermal conductivity may be greater in sea ice, or one of the reasons why it melts and also accretes so quickly.

Pjie2

Hi Wayne. In the second sentence on your site, you say "...sea ice must warm or cool faster than surface air, this is impossible with a standard physics interpretation."

This is wrong, it's perfectly possible for a surface to warm or cool faster than the overlying air, as anyone who's ever stood in the sun or found frost on their car windshield in the morning can tell you!

In particular, you can get frost forming on nights where the air temperature never goes below freezing. The thermal capacity of the air is low, as is the efficiency of heat transfer between (solid) surface and (gas) air. Thus the heating or cooling of the surface itself is dominated by the radiative flux rather than by conduction. Since the surfaces are radiating straight up to the night sky and the cosmic microwave background (-270 degrees C), this means they can lose heat rapidly and drop well below the ambient air temperature. You end up with a very steep temperature gradient above the surface, with the surface being below freezing, and the air temperature even a few centimetres higher being above freezing.

wayne

"who's ever stood in the sun or found frost on their car windshield in the morning can tell you!"

Hi Pjie2

In the morning after several hours of over night radiative cooling the ground is just as cold as the air, in fact it may be cooler than the air. Standing in front of the sun is an impression best sensed in a warmer atmosphere, try standing in the sun at -20 C and see how warm it is.

Or try an experiment, place water in a freezer and see how long it takes for water to change temperature, if you want it fancy, place water in a container half filled with water and air. See which one cools first.

Pjie2

"in fact it may be cooler than the air"

Yes, precisely. So why does the second sentence on your website say that ice cooling faster than air "is impossible with a standard physics interpretation"?

It's perfectly ordinary physics.

wayne

Pje2, , after several hours, perhaps 8 or more, that is not a nearly instant thermal response as suggested on my blog. Its all physics, but sometimes physics is extraordinary and requires more study.

Kevin McKinney

"…cooler than the air…"

Indeed. Readers may be interested in the investigations of William Charles Wells, who investigated the phenomenon of dew in the 1810s, winning the Royal Society's Rumford Medal for his considerable pains. (Also, later, the admiration of none other than John Tyndall.)

Having considered these “circumstances” affecting the formation of dew, Wells examines the “circumstances” affecting the cold which is dew’s precursor: on clear, still nights, the grass would become much cooler than the air temperature (customarily measured at 4 feet); long grass would cool more than short grass; and wind or cloud tended to eliminate this difference in temperature—although high cloud “would yet frequently allow of the grass being several degrees colder than the air.” The ground beneath the grass would be warmer; metal lying upon the grass tended to be warmer, too.

http://doc-snow.hubpages.com/hub/Global-Warming-Science-In-The-Age-Of-Washington-And-Jefferson-William-Charles-Wells

wayne

Hi Kevin, that is an easy familiar one, now try find one about sea ice.
Not at all the same as land in the morr'n. I believe that mixing land effects same as sea ice, as part of the larger problem of understanding, or rather misunderstanding sea ice interactions.

George Phillies

Readers interested in seeing melt ponds, open water, floating ice, landfast ice, and melting frozen soil, all in one picture in which you can see small details, may find the Barrow webcam http://feeder.gina.alaska.edu/webcam-uaf-barrow-seaice-images/current/image
to be of some interest.

wayne

Yes I added Theory Vs Observation discussion, its not as simple as morning dew, or feeling the noon sun at 70 degrees elevation. Simple physics may be warped into something more exotic and interesting, but first one must observe it. http://eh2r.blogspot.ca/

P-maker

A new observation-based Nature paper is out:

http://www.nature.com/news/climate-science-understand-arctic-methane-variability-1.15196

trying to make the link between melt ponds and methane emissions.

It turns out that 2007 had the highest growth rate in atmospheric methane concentrations.

Joffan7

You're quite right to be clear about how you are using "good" in "a really good start to the melting season, so good that...". Even better than footnoting might be to use a different adjective; "strong", perhaps?

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