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Artful Dodger

The surface layer in the Arctic Ocean is typically 100 to 150 m deep. Unlike fresh water lakes, when the surface of the Arctic Ocean cools, the water sinks and is replaced by deeper, warmer water in a kind of overturning circulation. As a dramatic illustration, note that sea surface temperatures in the southern Chukchi sea was still +4 C in early January 2010!

As a consequence, the entire surface water column must be chilled to below -1.8 C before the surface will freeze. Alternatively, melt continues as long as the surface layer remains above -1.8 C and there is sufficient mechanical turbulence to prevent an insulating fresh water boundary layer from forming around the ice. This situation holds as long as the salinity of the surface layer remains above about 30 psu, which again is strongly dependent on surface mixing.

Wind and wave action strips the layer of fresh melt water away from the ice edge and underside of an ice floe, and replaces it with more warm sea water. This is why recent strong winds resulted in enhanced melt throughout the Arctic. And this is why the Arctic Dipole anomaly is so important for extended melt in the Fall. While the winds blow, the melt continues, until the whole surface layer reaches -1.8 C, This is when freeze-up begins in earnest, but it can be long after the Sun sets.

Andrew Xnn

Interesting to see the huge area of cool (pink) over the Arctic around September 1st has dissipated by the 10th.

Locally (Great Lakes region) our weather was warm up until September 3rd, then a big shift of cool air from the north invaded and we've had a stretch of cool. So, from this, it looks to me as tho the Great Lakes region can serve as an outlet for cold air of the Arctic.

I've looking at the animation to try and figure out where else the cold arctic air may have gone to, but can't really pick it out. It probably went all over the place, but I know that we can get our share too.

fredt34

European sea temperature maps are computed with the Mercator model. They're avail at http://bulletin.mercator-ocean.fr/html/produits/bestproduct/welcome_fr.jsp?nom=bestproduct_20100908_22165&zone=arc for today in Arctic. Forecasts for one and two weeks are also avail.
Also, August air anomalies are avail on Jim Hansen's site, please see http://www.columbia.edu/%7Emhs119/Temperature/RecentT.gif (do we really need to use html syntax to display images??)

Daniel Bailey

Re: Andrew Xnn

I live in the Upper Peninsula of Michigan (Marquette). When the Arctic Oscillation goes negative, the tendency for colder polar air is to sink southward across the Great Plains and Great Lakes. Like you point out, we are experiencing those conditions now. When the AO was positive back in August, we had wonderful 80-degree weather. When it flipped negative, we dropped into the 50-60 degree range.

The NOAA AO website doesn't pertain beyond the US, so I cannot comment accurately if that cold air sinks elsewhere at a specific time. I do know that this past winter, when the AO went deeply negative the UK and Northern Europe had a lot of cold air some their way for an extended stay.

The projections for September are for the AO to deepen somewhat. Hopefully that corresponds to milder polar temps, stronger winds for more surface water overturning (increased melt) and strong PIPS arrows for ice excretion into the North Atlantic. I still have hopes for Logicman's prediction of possibly catching 2007 coming true. :)

The Yooper

Phil263

An increase of 10 k (before correction) reported by IJIS for 11 Sept. Will 10 Sept be the minimum extent for this year?

Kevin McKinney

No knowing just yet, Phil--could be. It's in the laps of the weather gods to a considerable degree. My gut feeling, though, is that we'll get one more episode of declines, for reasons that I've mentioned previously.

As always--we'll see! And rather soon, too.

Artful Dodger

2010 is now a dead heat for Sea Ice Area according to the IJIS Area chart. Even if there is no more melt, compaction could bring 2010 below 2008 levels for SIE. If there is no more compaction, the spread out Ice will be more vulnerable to rapid melt next year. What other records are lurking about?

NSIDC reports SIE based on a 30% concentration cutoff. Their posted SIE value for Sep 10, 2010 was 4.68 M sq.km (+/- 0.02 M):

Since IJIS uses a 15 % cutoff and reported 4.95 M sq.km for Sep 10, we know that there are about about 270,000 odd sq.km of Sea Ice Extent sitting between 15-30% concentration.

Going forward, all or none of this extent could plunge below 15% and be counted by IJIS as lost. WAG, say we lose half, so perhaps another 135,000 odd sq.km loss before the bottom? This neglects 'compaction', which would be counted as additional loses in SIE (although we know it's still Ice ;^).

Does anyone know offhand what the NSIDC minimum daily SIE values were for 2006-9? Is 2010 close to any of them now?

r w Langford

Fred34; Your link to European sea temps is interesting. Warm surface water appears to still be moving north from many directions, both Asia and Canada. This little animation from your recommended site shows what the ice is encountering this fall. http://bulletin.mercator-ocean.fr/html/produits/bestproduct/welcome_anim_fr.jsp?zone=arc
To see a longer period pick an earlier date and click l'ancer. Quite dramatic to see how sea temperature is behaving. Still some calories to be used up melting ice before
freezeup can take place.

Neven

European sea temperature maps are computed with the Mercator model.

Génial, merci!

An increase of 10 k (before correction) reported by IJIS for 11 Sept. Will 10 Sept be the minimum extent for this year?

Could be, but according to weather forecasts a high might establish itself more firmly again over the Canadian Archipelago, leading perhaps to some more extent reduction. Too bad PIPS is not updating their ice displacement maps as regularly as they were just a few days ago.

fredt34

Damnit, my IP (and my not-so-good English) revealed I'm french. I'll post some explanations about how to use that page when I'm back on a real keyboard. But the high temps are striking.

I don't know if the Catlin arctic plan to go North again in "spring", but I'd love to see them plug some equipments in remaining big pieces of ice so we can get realtime data about melt and drift. I mean, putting buoys into the ice chunks.

L. Hamilton

Lodger, the NSIDC graph I'm watching says "extent" refers to 15% concentration, same as IJIS, so I assumed there was some other explanation for their current divergence.

Does anyone know a public source of daily numerical daily behind the graphs other than IJIS extent and CT area?

WhiteBeard

fredt34,

It's likely the IP, as your conversational style English, it seems to me, is flawless until your confession @ 16:47. The phrase most often used by well educated native speakers is less than perfect, as a forme de sous-ton. A further subtlety would be using not-so-good in this context as autodérision, and, in other framing, as slight moquerie without the quote marks, or ridicule with quotes.

The plural of equipment is equipment - without the ending "s".

I see those two quite often from non native speakers. I'm only commenting because, from this small sample, you're very good.

un immortel de la pseudo-Académie - using the Dictionary.Com translator. ;)

Neven

Pas du tout, pas du tout. In my TypePad stats I can see the links through which visitors get here. I saw a French forum, went over there and then saw fredt34's name. C'est tout. Besides the Mercator-website is French. If it weren't for that I'd never known you were from France, fredt34. Which is a great, great compliment, considering you are French (no, I won't post that Youtube vid of John Cleese). :-)

I wouldn't know how to trace someone's IP, but watch out for Lodger. He can guess the colour of your underwear through your IP. ;-)

Artful Dodger

It's Not a guess Neven, but a probability surface at the 95% Confidence Level ;^)

SIE for Sep 13, 2010 (preliem) 4,995,625 km^2 for a daily loss of -9,375 km^2.

Artful Dodger

The freezing point of water is a function of it's salinity, "s". So we can transform the scale of our Arctic Salinity map into a Freezing Point "s(t)" map, to estimate how freezing will occur:Freezing Point (oC)
Freezing Point (oC)
Salinity Legend (psu)

Christoffer Ladstein

Chuckling my pants of for the conversational level this blog is kept on :/). I must say I find it kind of a thrill how diversified all of us keeping this blog both mindboggling and civilized. Nationality and background doesn't count, but of course those of us derived from non-english speaking countries, will struggle harder to achieve the easygoing witty style that is befallen the "natives" out there. That for instance Lodger-Dodger is a true wizard in many fields, isn't exactly an exaggeration. Myself I'm just a "humble" Gardener, carrying around with some extra University degrees in the rucksack, periodically driving my wife nuts with my "bizzarre" hobbies, which is quite understandable!

Back so subject: The negative NAO for the past winter, making the past winter the coldest in the Western part of Norway (read: Bergen) for more than 150 years, was probably the strongest and most persistent for centuries ( http://europa.agu.org/?view=article&uri=/journals/gl/gl1014/2010GL043830/2010GL043830.xml&t=Seager ), and hencefort not likely to reappear to soon. This negative NAO was the main reason for the late date of SIA maximum this spring, i believe.

Lodger: That salinisation map might show there is still hope of further meltdown north of Svalbard/Novaja Selmja, but that is mainly thanks to the Gulf stream, so there isn't really any big surprises left, is it?

Artful Dodger

Takk, Christoffer! I think you're right, unless the DA restarts soon. If the main pack does freeze in place without further significant compaction, the Fall/Winter Ice export through Fram Strait will be monumental. Either way, bad new for the "Recovery".

Enjoy this new article on Explorer's Web about our Norse heroes and their Russian mates on Peter 1:
http://explorersweb.com/oceans/news.php?id=19641

Christoffer Ladstein

These rather grim prospects just show what I've been telling for some weeks now: These 2 teams are roughly 7-10 days behind schedule, which might prove dramatic in the next 2 weeks... This adventure is ALMOST as exciting as the more slow churning melodrama of the Arctic! At least this latter "drama" will keep rentering the "stage" as long as we keep crawling around on Terra.

Artful Dodger

The Sun has set on 2010 at the N. Pole. Next MODIS sunrise March 29, 2011.

NASA Image for 2010/257 (09/14/10):
http://rapidfire.sci.gsfc.nasa.gov/subsets/?mosaic=Arctic.2010257.terra.4km

Jon/Charles/Larry: Thanks for helping to get the various ice-rules sorted ;^)

Artful Dodger

Christoffer Ladstein | September 14, 2010 at 12:50

"...so there isn't really any big surprises left, is it?"

Well, maybe one more surprise... At 12:00 UTC a large Low is transiting the North coast of Siberia, creating strong Easterly winds in the East Siberian Sea. The tongue of Sea Ice present there is starting to tear apart near 165 E 78 N.

The tearing event is apparent on time series of Uni-Bremen and Uni-Hamburg maps, and there is good MODIS visibility of the region today.

If the tear manages to completely separate the ice tongue from the main pack, this free-floating mass could move West rapidly, and rejoin the main pack near Severnaya Zemlya. From there, it would then be advected through Fram Strait, perhaps as early as this Fall / Winter. This would be a full year ahead of the expected time to lose Sea Ice from the E. Siberian Sea. How surprising is that?

Christoffer Ladstein

Artful: Yes, the remains of the ice in this "tongue" seem very able to vanish until mid- October. What you imply by this drifting normality-theory must also in 2007, have been a year with no multiyear ice left from the E. Siberian Sea?
I'm starting to get incredibly excited just how much multiyear ice there will be left for next season, over the latest years it's been steadily dropping, so if the NAO will stay put 3 months in a row next summer, we will definitly be able to "surf the Northpole". The point of North Pole isn't either the most common place for ice to "get stuck", that's closer to Greenland/Canadian Archipelago.

If this Low pressure keep developing, the seesaw will endure for a longer period of time, making the SIA extent for the autumn look more similar to 2007, or don't we have warm enough sea to keep that theory alive?

Artful Dodger

Fall is the Ice Advection season, and it's all about losing or retaining the oldest, thickest ice. This is the under-reported story of the Arctic. Once all the multi-year ice is gone, we will have sea ice-free Summers each year as the new saltier ice melts out quickly and completely.

Lord Soth

Re: Early Sunset

My understanding is that on Sept 22, the sun will be half above the horizon at the North Pole. The disk of the sun will not actually sink below the horizon until Sept 24. Then for almost two weeks we will get twilight (white nights) at the pole.

The MODIS imagery does get a little wanky about a week before sunset however. May have something to do with the incidence angle of the sun, and low light levels. If anybody has a definite explanation, I would be interested.

I still figure that we have a 50/50 chance for a late minimun. The Laptev and E. Siberian sea will continue to melt until the end of the month. Any new ice that forms in the arctic must go thru the frazil, nilas stage before it becomes grey white ice. I suspect that anything less than grey-white ice will not show up in the sat photos.

We are only 50,000 km above the minimun, and we have about a week left for compaction to have any effect. We could stil have another 100-200K drop in store, but it will all depend on the wind patterns.

Christoffer Ladstein

Crazy! The graph is going nuts http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic

Seems like the line came across a "hole in the ice", :-).

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