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ra3000

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Re: The 2015 melting season
« Reply #4001 on: September 09, 2015, 01:37:58 AM »
I bet the Arctic Sea Ice refreeze will start actually in Beaufort.

Rick Aster

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Re: The 2015 melting season
« Reply #4002 on: September 09, 2015, 02:21:24 AM »
Just for laughs I repeated my 2 million square kilometer graphic from a year ago. In August 2014 I tried to position a 1000 x 2000 km rectangle over what at that time looked like the ice with the best staying power. This shows the 2014 rectangle over the current ice according to the latest AMSR2 map. It’s one way of thinking about how much things can change in a year. If I were drawing a box around the core of this year's ice I might prefer a square.

slow wing

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Re: The 2015 melting season
« Reply #4003 on: September 09, 2015, 04:09:58 AM »
The Pacific side appears to still be melting, along with some dispersion at the moment (as discussed above by SeaIceSailor).

The U. Bremen update shows perhaps the worst ice condition it has shown so far this melt season for all of: the dregs of the Beaufort Arm, the ESS forearm, and the ice around and inside 80N in front of the Beaufort Sea.

Click on gif to crossfade between the two latest daily ice concentration maps (apologies for the poor quality of the gif)...


Pmt111500

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Re: The 2015 melting season
« Reply #4004 on: September 09, 2015, 04:37:43 AM »
As there's a Pacific reorganization of air-pressure going on (developing el nino), there's no surprise that the Atlantic side of the pack has been pretty impervious to the melting factors of the Atlantic currents this year. The domination of the Pacific over the Atlantic as the global regulator of wind directions is becoming clearer. If that didn't make sense it's likely my fault.

helorime

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Re: The 2015 melting season
« Reply #4005 on: September 09, 2015, 06:47:55 AM »
There is still a lot of action in the ESS, look at this pair of images, top is Sept 4, bottom is Sept 7
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DavidR

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Re: The 2015 melting season
« Reply #4006 on: September 09, 2015, 10:14:09 AM »
As there's a Pacific reorganization of air-pressure going on (developing el nino), there's no surprise that the Atlantic side of the pack has been pretty impervious to the melting factors of the Atlantic currents this year. The domination of the Pacific over the Atlantic as the global regulator of wind directions is becoming clearer. If that didn't make sense it's likely my fault.
The Atlantic side of the ice appears to be fracturing quite significantly at the moment, which may  be putting a halt to extent declines.
I've been wondering if the reason the Atlantic has been slow to  melt this year has been because of the frequent  mini cyclones in winter which  kept  pushing the Ice in the Barents in to the CAB. Presumably this made the area more compact  and solid.
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DavidR

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Re: The 2015 melting season
« Reply #4007 on: September 09, 2015, 10:17:30 AM »
NOAA has rated August as the fourth hottest month on record but not in the top 15 for August in the Arctic. The strong melt in August  must  be due to the heat in the ocean in July.
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Killian

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Re: The 2015 melting season
« Reply #4008 on: September 09, 2015, 11:13:10 AM »
Hey all,

I have looked for evidence of the truly massive rise in ASI Area around day 231/32 and really don't see it. Now, these being models, we kind of get stuck with the declines subsequent being tied to that increase that seems, best I can tell, to be a problem with the model counting, what?, thin, temporary slush as resilient ice? 

Basically, I think the rise is false or mostly false and the decline real, and if that is correct, we have a gross miss-count of ASI area.

So, does that seemingly unprecedented rise hold up? I could never find the corresponding growth.

http://meteomodel.pl/index.php/arcticice

AmbiValent

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Re: The 2015 melting season
« Reply #4009 on: September 09, 2015, 11:43:07 AM »
I think what you're referring to is melt ponds in the CAB (which were registered as water) freezing over. Since they were made of still freshwater, they froze earlier than moving saltwater.
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Re: The 2015 melting season
« Reply #4010 on: September 09, 2015, 12:47:44 PM »
I'll put in a guess that the extent minimum arrives on 15th Sept, on the assumptions that:
  a) effects of compaction will ease off around then, and
  b) stray bits of ice in more southerly latitudes will have more or less finished melting

seaicesailor

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Re: The 2015 melting season
« Reply #4011 on: September 09, 2015, 02:38:09 PM »
Below are the rankings for 925hPa air temperatures north of 72.5N, based on the ncep reanalysis for since 1948.

[...]


Extremely interesting statistics!!

Compare 2011 and 2015

Year    May..June...July.Aug.MJJA
2011   7.......5.....1.....2.....1
2015   27....11.....2....26....13

These years shared similarities since the beginning of the season (remember Vid?). Even the shape of the final pack has a lot in common. And July month.

However see August 26th position! And yet the huge wreck that three weak cold storms caused over the already broken MYI Beaufort ice, and the compaction from the relatively cold Laptev area. Then the final storm.

And May in 27th position, which saw a warmth wave in Alaska and Canada, with South winds that opened up the Beaufort sea and Chukchi kicking in albedo effect, a preconditioning element that, in absence of it, melting would have been delayed.

Then snow cover preconditioning due to Winter weather. Not accounted for in these statistics.

Overall averaged temperatures are extremely misleading. Local temperatures 850hpa-925hpa and land surface temps can be significant though, especially in Peripheral areas during May-June.

This year we also had the out-of-mind hot Pacific and the few systems it brought to the Arctic, sometimes via North America, sometimes warm advection, other times not-so-warm systems like the big Chukchi August storm. You can have more and more heat being transported to the Arctic Ocean, under what seems overall cool temperatures. Then the ocean stores heat and releases it later in the season.


« Last Edit: September 09, 2015, 05:06:44 PM by seaicesailor »

Frivolousz21

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Re: The 2015 melting season
« Reply #4012 on: September 09, 2015, 06:10:16 PM »
IMO the snow albedo effect rules this seasons fortunes.

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BornFromTheVoid

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Re: The 2015 melting season
« Reply #4013 on: September 09, 2015, 10:09:01 PM »
Below are the rankings for 925hPa air temperatures north of 72.5N, based on the ncep reanalysis for since 1948.

[...]


Extremely interesting statistics!!

Compare 2011 and 2015

Year    May..June...July.Aug.MJJA
2011   7.......5.....1.....2.....1
2015   27....11.....2....26....13

These years shared similarities since the beginning of the season (remember Vid?). Even the shape of the final pack has a lot in common. And July month.

However see August 26th position! And yet the huge wreck that three weak cold storms caused over the already broken MYI Beaufort ice, and the compaction from the relatively cold Laptev area. Then the final storm.

And May in 27th position, which saw a warmth wave in Alaska and Canada, with South winds that opened up the Beaufort sea and Chukchi kicking in albedo effect, a preconditioning element that, in absence of it, melting would have been delayed.

Then snow cover preconditioning due to Winter weather. Not accounted for in these statistics.

Overall averaged temperatures are extremely misleading. Local temperatures 850hpa-925hpa and land surface temps can be significant though, especially in Peripheral areas during May-June.

This year we also had the out-of-mind hot Pacific and the few systems it brought to the Arctic, sometimes via North America, sometimes warm advection, other times not-so-warm systems like the big Chukchi August storm. You can have more and more heat being transported to the Arctic Ocean, under what seems overall cool temperatures. Then the ocean stores heat and releases it later in the season.

Any generalised area isn't going to capture the regional details. On top of that, north of 72.5N isn't the best representation of the Arctic, as it includes areas south of Svalbard which rarely have any ice, and misses out on parts of the Pacific side of the Arctic ocean, especially Chukchi and Beaufort. However, if you starting using latitudes that are further south, you begin to incorporate more and more of the Eurasian land mass, which can massively skew things.

What is the snow pre-conditioning you'e referring to?
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slow wing

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Re: The 2015 melting season
« Reply #4014 on: September 10, 2015, 04:32:40 AM »
In today's U. Bremen update, it looks like the entire ice pack has been pushed bodily in the direction of Alaska. The ice edge on Atlantic side has retreated towards the Pole while that on the Pacific side has moved away from the Pole.


  Climate Reanalyser shows a big dipole setting up, with a low pressure system around the Pole and a high pressure system on the Pacific side.

  The low pressure system is dumping snow on the ice around the Pole. If that snow doesn't get a chance to melt before Winter then this is the most effective time for the snow blanket to insulate the ice and retard its thickening over the Winter.

  Due to the trapped air every cm of snow gives the equivalent insulation to around 20 cm of ice. It retards ice growth from the bottom, at its interface with the ocean water, by slowing the heat flux draining from the water, through the ice and into the Arctic Winter sky. Then, next Summer, it will melt quickly - insulating job done - with each cm of snow only requiring as much heat energy as about 1 mm of ice.

  So it's going to be very interesting to see how much snow falls just after the re-freeze. Does anyone know if the snow cover information is modelled and recorded in a map of snow thickness at any given time?

Click on gif to see the ice pack movement since yesterday's map...
 
« Last Edit: September 10, 2015, 04:42:33 AM by slow wing »

Blizzard_of_Oz

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Re: The 2015 melting season
« Reply #4015 on: September 10, 2015, 07:29:34 AM »

Any generalised area isn't going to capture the regional details. On top of that, north of 72.5N isn't the best representation of the Arctic, as it includes areas south of Svalbard which rarely have any ice ...

Agreed - temperature is by no means a completely informative diagnostic.

Though for what it's worth, see the "Monthly Temp. Ranks" link in the side menu here:
http://cires1.colorado.edu/~aslater/ARCTIC_TAIR/

See the "About these pages" link for a map of the region that makes the average.

BornFromTheVoid

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Re: The 2015 melting season
« Reply #4016 on: September 10, 2015, 08:52:08 AM »
Cheers, I didn't realise that had a rankings sections, makes the table I posted somewhat redundant. They do appear somewhat similar though, in showing that 2015 nowhere near the warmest overall despite a very mild July.
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seaicesailor

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Re: The 2015 melting season
« Reply #4017 on: September 10, 2015, 09:02:40 AM »

What is the snow pre-conditioning you'e referring to?

Yes, I meant the low snow cover on top of the ice in Spring that had its cause earlier, and thus cannot be reflected on these temp statistics. And also the low cover in the continents (above and below 72N) end of June, which still should contribute to Arctic Amplification.

And related to this, @slow wing, early snow insulation may have the effect you say, but it has a very high albedo, and takes time to melt out, delaying ice surface melt come Spring; just as Friv notes compare this year to 2014. It may not be the amount of heat needed (you say little for melting snow compared to ice), but when it is substracted. A few days of ice melt delay mean a lot of m3 of ice preserved later, due to delay of albedo amplification. Time clocks fast and Solstice is right there when melting starts ... :--)

BFTV I really thank you for these numbers.



slow wing

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Re: The 2015 melting season
« Reply #4018 on: September 10, 2015, 10:29:00 AM »
And related to this, @slow wing, early snow insulation may have the effect you say, but it has a very high albedo, and takes time to melt out, delaying ice surface melt come Spring; just as Friv notes compare this year to 2014. It may not be the amount of heat needed (you say little for melting snow compared to ice), but when it is substracted. A few days of ice melt delay mean a lot of m3 of ice preserved later, due to delay of albedo amplification. Time clocks fast and Solstice is right there when melting starts ... :--)
Ice has high albedo as well. So 1 cm of snow now on thin ice might retard Winter thickening by ~10 cm of ice. (See useful plot of ice thickness growth rate vs. ice thickness that has been posted several times on this forum.) Then it will only take up the heat equivalent of 0.1 cm of ice to melt out.

So I'm fairly sure that the net effect of snow now will almost always be to speed up the melt out of any ice it lands on.

crandles

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Re: The 2015 melting season
« Reply #4019 on: September 10, 2015, 11:45:48 AM »

Ice has high albedo as well.


So I'm fairly sure that the net effect of snow now will almost always be to speed up the melt out of any ice it lands on.

I think no to '(Edit: almost) always speed up melt out'. Ice has lower albedo though not as low as melt ponds or open water:



So more snow in fall means the ice is thinner due to insulation. However, there is more dry snow with high albedo so this takes more time to melt and the melt season gets off to a slow start. Some years it seems like the slow start is crucial.
« Last Edit: September 10, 2015, 01:47:24 PM by crandles »

slow wing

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Re: The 2015 melting season
« Reply #4020 on: September 10, 2015, 12:49:35 PM »
Ah c'mon! When I write "almost always" please don't start quoting me at "always" and then object...  ;)


Two points:

  1) If we're comparing the direct sunlight melting of an extra 1 cm of snow cover vs. an extra 10 cm of ice then that much ice requires of order 100 times the heat to melt out compared to that much snow. So even if the ice is absorbing say 3 times as much of the sunlight (snow/ice albedo = 0.85/0.55) it will still take about 30 times as long to melt.

  2) other heat sources - e.g. water vapour, warm air and and longwave radiation - won't favour heating ice over snow to the same extent, if at all.
« Last Edit: September 10, 2015, 01:04:27 PM by slow wing »

budmantis

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Re: The 2015 melting season
« Reply #4021 on: September 10, 2015, 09:42:45 PM »
Interesting I called for a potentially historic minimum and an early start to the refreeze in the beginning of August and everyone wanted to rip my head off...Right now it looks like day 244 maybe the actual minimum making it the earliest in the satellite era by one day. 1987 the minimum was set on  day 245....Interesting indeed

It'll be even more interesting in another week.

Steven

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Re: The 2015 melting season
« Reply #4022 on: September 10, 2015, 10:35:15 PM »
Due to the trapped air every cm of snow gives the equivalent insulation to around 20 cm of ice.

That may be true for freshly fallen snow.  But for old, compacted snow that number is an overestimate.

Semtner, 1975 on page 2 gives the following "empirical" values for the thermal conductivities of sea ice and snow in the Arctic in the freezing season:


thermal conductivity of snow ≈ 0.31 W m-1 K-1   (≈ 7.4 10-4 cal cm-1 s-1 K-1)

thermal conductivity of sea ice ≈ 2.0 W m-1 K-1   (≈ 4.86 10-3 cal cm-1 s-1 K-1)


This implies that every centimeter of snow gives the equivalent insulation of about 6.5 cm of ice (because 2.0/0.31 ≈ 6.5).  This is a ballpark estimate; in practice this will depend on factors such as snow density, e.g. see the graph below (source), which shows thermal conductivity of snow as a function of the snow density:



slow wing

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Re: The 2015 melting season
« Reply #4023 on: September 11, 2015, 05:12:29 AM »
Thanks Steven, that's very interesting. So it appears the Arctic Winter snow is usually denser  than fresh dry snow and so a less good insulator.

The rule of thumb I remember for fresh snow is 1 foot of snow is as much water as 1 inch of rain (US Imperial units) - so a density of 1/12 g/cm^3 and corresponding to the leftmost data points on the plot. The 'center of data' point on the plot is around 0.3 g/cm^3, so more than three times the density of fresh dry snow.

Not sure how the snow gets compacted? Could be melt-refreeze cycles? The density would presumably also depend on whether the snow fell dry or as wet slush.

There is a lot of scatter in the plot as well, so a lot of uncertainty unless the specific properties of the fallen snow are known.
« Last Edit: September 11, 2015, 05:19:08 AM by slow wing »

slow wing

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Re: The 2015 melting season
« Reply #4024 on: September 11, 2015, 05:25:35 AM »
Still plenty of wind in the Arctic and it shows up as the pack edges moving around in the U Bremen map update. Concentrations are increasing in some areas, decreasing in others - so we haven't yet reached full-on freeze up.

Most spectacular is the dispersion on the Atlantic side, which the Aqua satellite images shows to be due to long cracks through most, if not all, of the Atlantic-side ice pack. A greater degree of crumbling is also seen close to the ice pack edge.

Click on gif for the comparison between yesterday's and today's maps...
 

Adam Ash

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Re: The 2015 melting season
« Reply #4025 on: September 11, 2015, 06:05:57 AM »
At the scale of these images (refer the 100 km scale bar) these fractures must be at least a kilometre wide to show up at all. 

The implication of what was near-continuous wall-to-wall ice with numerous series of leads cutting through it almost all the way to the Pole will be interesting to discern in the coming months. 

My guess is that these leads will allow localised rotation and jostling of slabs of the ice, with consequential on-going erosion and break-up of the edge of each slab, even when the slab (which is many kilometres in extent) is thickening due to re-freeze, and the water between the slabs is also building first-year ice.  So we may start the next melt season with lots of first year ice interspersed among these existing (by then) second year-old slabs over most of the CAA. 

Mmmm...

Michael Hauber

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Re: The 2015 melting season
« Reply #4026 on: September 11, 2015, 07:48:00 AM »
Ice that is solid enough to show up large scale cracking patterns is a bit of a surprise to me.  For the last few years at around this date we have been looking at slushy floes near the north pole speculating on whether a large enough area of water might open up to declare the pole 'ice free'.
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Re: The 2015 melting season
« Reply #4027 on: September 11, 2015, 08:25:40 AM »
Here is a gif over on the Laptev / ESS area from Sept 3, 4, 8, 11 at the 50 km scale.  There's a lot more wind heading to that area, will be interesting to see what develops.
FNORD

seaicesailor

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Re: The 2015 melting season
« Reply #4028 on: September 11, 2015, 12:53:28 PM »
Here is a gif over on the Laptev / ESS area from Sept 3, 4, 8, 11 at the 50 km scale.  There's a lot more wind heading to that area, will be interesting to see what develops.

Looks to me that the ESS Arm is showing signs of break up due to winds, and at the same time, refreezing around its edge.

Steven

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Re: The 2015 melting season
« Reply #4029 on: September 11, 2015, 01:30:52 PM »
that's very interesting. So it appears the Arctic Winter snow is usually denser  than fresh dry snow and so a less good insulator.

The rule of thumb I remember for fresh snow is 1 foot of snow is as much water as 1 inch of rain (US Imperial units) - so a density of 1/12 g/cm^3 and corresponding to the leftmost data points on the plot. The 'center of data' point on the plot is around 0.3 g/cm^3, so more than three times the density of fresh dry snow.

Yes, freshly fallen dry snow has a density of less than 0.1 g/cm3, whereas the typical density of the snow layers on the arctic sea ice in winter seems to be about 0.3 g/cm3.

Melt-refreeze cycles in early autumn seem to play a role in compacting the snow.  And thick snow layer may be compacted somewhat by gravity.

The graph below shows the average snow density for each month as measured at drifting stations on Arctic sea ice.  Source: Warren et al. 1999.  The average snow density in the freezing season is about 0.3 g/cm3 (= 300 kg/m3), consistent with the numbers mentioned before.  It gradually increases from about 0.25 g/cm3 in September, to 0.32 g/cm3 in April and May.



« Last Edit: September 11, 2015, 02:37:10 PM by Steven »

Jim Pettit

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Re: The 2015 melting season
« Reply #4030 on: September 11, 2015, 05:32:04 PM »
Interesting I called for a potentially historic minimum and an early start to the refreeze in the beginning of August and everyone wanted to rip my head off...Right now it looks like day 244 maybe the actual minimum making it the earliest in the satellite era by one day. 1987 the minimum was set on  day 245....Interesting indeed

Well, to be fair to "everyone [who] wanted to rip [your] head off", your exact words were " I'm calling for a 4 week early start". And, of course, 1 day ≠ 28 days.
« Last Edit: September 11, 2015, 08:53:49 PM by Jim Pettit »

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Re: The 2015 melting season
« Reply #4031 on: September 11, 2015, 05:51:36 PM »
Do you think we are above the minimum now.
At least on the pacific side we should see increasing, i think at least area should get higher, and we have allready also some Extendrise until now.


It would be the soonest minimum for years and here



the ice near to ostasien can get some lost of course but the region north of alaska should refreeze soon.

This is a few days after and the 0 degree circle is much wider then the ice remaining.

I think we saw the minimum at boat are and extent.


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Re: The 2015 melting season
« Reply #4032 on: September 11, 2015, 09:49:12 PM »
I think what you're referring to is melt ponds in the CAB (which were registered as water) freezing over. Since they were made of still freshwater, they froze earlier than moving saltwater.

Then I'd expect to see many similar events, but I don't.

magnamentis

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Re: The 2015 melting season
« Reply #4033 on: September 11, 2015, 10:12:57 PM »
I think what you're referring to is melt ponds in the CAB (which were registered as water) freezing over. Since they were made of still freshwater, they froze earlier than moving saltwater.

Then I'd expect to see many similar events, but I don't.

why exactly would you expect many similar events. i mean the ice cover is so small now and that far north that i refroze within 2-3 days and never melted again, hence one event only. in years where the ice was compact above 80° north and the ponds were more south, the refreeze was regionally more dispersed IMO and due to be more south able to re-melt in places, hence no such significant hooks happen in the charts, while there are many enough though. if you understood wrong what you meant, please elaborate.

slow wing

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Re: The 2015 melting season
« Reply #4034 on: September 12, 2015, 04:08:48 AM »
Still no full-on re-freeze in today's U. Bremen update.

With a big high pressure system on the Pacific side, the ice pack edge is pushing in hard from the Laptev Sea while the Pacific and Atlantic sides are both bulging out.


The MODIS Worldview satellite images are showing long cracks everywhere on the Altantic side, including all around the Pole:
https://earthdata.nasa.gov/labs/worldview/?p=arctic&l=MODIS_Aqua_CorrectedReflectance_TrueColor,MODIS_Terra_CorrectedReflectance_TrueColor,Graticule,Reference_Labels(hidden),Reference_Features(hidden),Coastlines&t=2015-09-11&v=-919313.2307214282,-423104.2675485037,983278.7692785718,595775.7324514963

Click on gif to see ice movement since yesterday:

NeilT

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Re: The 2015 melting season
« Reply #4035 on: September 12, 2015, 11:18:58 AM »
I note that the deep water channel of the NW passage is now fully open.  Neven was right on that one.  Ice continues to melt and the CT Area continues to fall.

I'm not so fussed with records.  More solid trends.  Regardless of "growth" or "rebound" or any other fancy term, every year post 2007 is reacting like a state change happened in 2007 which has not changed back.

There is no hint that things are going to return to pre 2007 levels.  Which, to me, means that no matter what the final graphs show, the trend continues and, one year, pretty soon, there will be so much ice lost in summer that it will be obvious to the most hardened idiot that our cryosphere has changed and is releasing it's stored cold back to the planet in order to try and cool it.
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crandles

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Re: The 2015 melting season
« Reply #4036 on: September 12, 2015, 11:58:35 AM »
Regardless of "growth" or "rebound" or any other fancy term, every year post 2007 is reacting like a state change happened in 2007 which has not changed back.

There is no hint that things are going to return to pre 2007 levels.  Which, to me, means that no matter what the final graphs show, the trend continues and, one year, pretty soon, there will be so much ice lost in summer that it will be obvious to the most hardened idiot that our cryosphere has changed and is releasing it's stored cold back to the planet in order to try and cool it.

Above post seems designed to provoke:

https://tamino.wordpress.com/2015/09/06/change-point-fun/

Statistically significant state change happened in 2006 changing to slower rate of decline.

Pretty soon it will be obvious to the most hardened idiot that less ice means that more heat can be lost in winter allowing a slower decline in ice and the rapid phase from 2002 to 2006 was just replacement of MYI with FYI that just could not continue.

 ;)

(OK, no I don't believe the current slow rate means we will have sea ice in September in 50 years time. I think it will get interesting again. However comment seemed so much against the data it deserved this reaction.)

NeilT

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Re: The 2015 melting season
« Reply #4037 on: September 12, 2015, 01:24:55 PM »
Hmmm,  Yes, Extent.

Where 85% open water is counted exactly the same as 100% solid ice in previous decades.

But, even then.  Perhaps we could use this image for extent from the NSIDC.



Or the NSIDC SOTC montly Anomalies



Which show what I remember.  Namely that the decline started around 2002, jumped in 2005 and changed state in 2007.

Or even our own Wipneus PIOMAS graphs



And finally the Anomaly trace from CT.  Which shows several distinct anomaly phases.



I'm not being inflammatory.  The response mechanisms of the Arctic Ice changed in 2005, changed state in 2007 and is stuck in that state now.

I don't believe I commented against the data.  I did, however, comment against a chart who's long term trend line has multiple baselines.

I thought that was against the rules????





Being right too soon is socially unacceptable.

Robert A. Heinlein

ktonine

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Re: The 2015 melting season
« Reply #4038 on: September 12, 2015, 02:33:22 PM »
I don't believe I commented against the data.  I did, however, comment against a chart who's long term trend line has multiple baselines.

I thought that was against the rules????

Huh?

Do you understand change point analysis?  Do you understand where, when, and why it is used?
 
Tamino doesn't give us multiple baselines, he provides multiple trend lines - that is sort of the whole point of change point analysis.

I think you have seriously misunderstood the rules.  If change point analysis isn't allowed, then many of the temperature datasets will also be in trouble.  It's one way to detect undocumented  station moves, equipment problems, TOBS changes, etc.


slow wing

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Re: The 2015 melting season
« Reply #4039 on: September 13, 2015, 04:01:10 AM »
The ice pack edge continues to retreat fast from the Laptev Sea, in today's U. Bremen update, while that on the Altantic side in particular bulges out, away from the Pole.

The Central Arctic Basin air temperature is heading well below freezing now - average temperature and even maximum temperature in most places there - as shown on Climate Reanalyser's 5-Day Outlook Maps page:
http://cci-reanalyzer.org/WeeklySummary/

Click on gif for comparison with yesterday:

seaicesailor

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Re: The 2015 melting season
« Reply #4040 on: September 13, 2015, 02:00:41 PM »
This gif compares Sep 7 and Sep 12. As slow wing reports well every day, the retreat in Laptev , the thinning of the ESS arm and the expansion in the Atlantic side are spectacular, as well as the gradual refreezing of the Pacific side.

Note that, even under dispersing winds straight from North, the loose ice close to CAA and Beaufort sea is still melting in situ, or so the images seem to indicate.

With the Beaufort high, surface temperatures go down and clockwise convergent drift will drag excess heat down.
Associated coastal upwelling too. If there was warm sub-surface water accumulated along the coast, it should delay refreezing at Beaufort sea coasts.



seaicesailor

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Re: The 2015 melting season
« Reply #4041 on: September 13, 2015, 02:21:40 PM »
Seems to me the upper part of the ESS arm is starting to look like sort of a sheep head, or goat head. My imagination  ::) :--)

NeilT

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Re: The 2015 melting season
« Reply #4042 on: September 13, 2015, 02:46:35 PM »
I don't believe I commented against the data.  I did, however, comment against a chart who's long term trend line has multiple baselines.

I thought that was against the rules????

Huh?

Do you understand change point analysis?  Do you understand where, when, and why it is used?
 
Tamino doesn't give us multiple baselines, he provides multiple trend lines - that is sort of the whole point of change point analysis.

OK I've just skimmed an article on change point analysis.

I stand corrected.  Cumulative change measured against average change.  Interesting.  But hardly representative on a system which counts an area of 15% ice as 100% ice, in comparison with a time when the same area was actually covered in 100% ice, as the same thing.

Also the chart there shows the very greatest annual changes as an almost flat line.  Why?  Because it's a cumulative value being compared with the long run average.  Which will smooth out any large annual moves.

So, in fact, as far as the arctic goes, the most damaging changes to the ice stability are smoothed out into nothing more than a smooth, slowly descending, line.  Whereas the small but continuous extent drops, post 2000, are highlighted as a change.  Why?  Because they shift the cumulative value, v the average value, over time.

This is even worse when applied to the anomaly count.  That anomaly value being applied to an already averaged baseline.  So a cumulative count of an average of an average.  The penultimate in smoothing out radical impacts or changes.

Anyway.  This season is almost over.  On to 2016 and 2017.  Where we can watch the lack of "change point" as represented by a cumulative count compared to an average.

Or Not.
Being right too soon is socially unacceptable.

Robert A. Heinlein

slow wing

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Re: The 2015 melting season
« Reply #4043 on: September 14, 2015, 04:08:43 AM »
The trend continues in today's U. Bremen update of the ice edge retreating fast from the Laptev Sea (now extending to the forearm projection at ~155E) while advancing away from the Pole on the Atlantic side.

There appears to be a net freeze-up amongst the lower concentration ice on the Pacific side. We'll see if that is confirmed tomorrow.

Click on gif to compare yesterday's and today's maps...


seaicesailor

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Re: The 2015 melting season
« Reply #4044 on: September 14, 2015, 06:07:23 AM »
Interesting I called for a potentially historic minimum and an early start to the refreeze in the beginning of August and everyone wanted to rip my head off...Right now it looks like day 244 maybe the actual minimum making it the earliest in the satellite era by one day. 1987 the minimum was set on  day 245....Interesting indeed

you were saying?

seaicesailor

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Re: The 2015 melting season
« Reply #4045 on: September 14, 2015, 06:25:38 AM »

It would be the soonest minimum for years and here




I don't want to discourage you, but in your first post you didn't exactly hit the mark

Lord M Vader

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Re: The 2015 melting season
« Reply #4046 on: September 14, 2015, 07:38:06 AM »
According to IJIS daily valuues we are right now 1154 km2 below the minimum of 2011. Thereby putting 2015 in most likely a third place behind 2012 and 2007.

Conclusion: While perhaps early, the minimum of 2015 won't be record early.

Gonzo

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Re: The 2015 melting season
« Reply #4047 on: September 14, 2015, 03:28:37 PM »
Lord M Vadar
Quote
Thereby putting 2015 in most likely a third place behind 2012 and 2007.
Would it be true to say that 2015 is the lowest minimum that was not ravaged by a cyclone?
2012 lost integrity due to major cyclone (not sure about 2007). In other words, possibly lowest on record just by melting alone? Thank god we didn't have a cyclone.
« Last Edit: September 14, 2015, 06:48:12 PM by Gonzo »

seaicesailor

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Re: The 2015 melting season
« Reply #4048 on: September 14, 2015, 03:35:24 PM »
Lord M Vadar
Quote
Thereby putting 2015 in most likely a third place behind 2012 and 2007.
... In other words, possibly lowest on record just by melting alone...

I agree, but main reason because practically there was not export through the Fram. A lot of ice was lost in 2007 and 2012 due to export, especially 2007. I'd see the movie of 2007 season at the "uiuc cryosphere today" site. Or any of the movies of "map of ice age" in youtube. It is very impressive IMO.

DavidR

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Re: The 2015 melting season
« Reply #4049 on: September 14, 2015, 11:44:22 PM »
For those of you  who missed it, Australia is pleased to  announce that Tony " Climate change is Crap" Abbott, our scientifically  illiterate Prime Minister   has been dumped by his own party in favour of a leader who is known to  have some understanding of the Climate problems we face.

Cheers!
Toto, I've a feeling we're not in Kansas anymore