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A-Team

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Re: The 2017/2018 freezing season
« Reply #900 on: February 16, 2018, 09:26:40 PM »
Quote
More and more open water over Chukchi Sea
Right. Looks like some upper Bering Sea water is being blown in over that 53 m sill, which will continue for the next five days or so. Below yellow shows open water and green solid ice (0% and 100% sea ice concentration respectively). It is not at all uncommon to see lift-off of ice from along the coasts or lee or Wrangel as the ice pack shifts around. These polynyas rapidly refreeze or close in as the ice pack shifts again.

However not all the open water in the last few days is in those categories; there is additionally quite a bit of mid-concentration ice. The 'large' version of UH AMSR2 provides better resolution for regions of limited extent; posterizing the average sea ice concentration over the last 46 days gives a better sense of what is stably affected in the Bering Strait region since the beginning of the year.
« Last Edit: February 16, 2018, 10:06:54 PM by A-Team »

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #901 on: February 16, 2018, 09:49:43 PM »
You think we had the maximum for this year  ?

No.

Iceismylife

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Re: The 2017/2018 freezing season
« Reply #902 on: February 16, 2018, 11:08:18 PM »
You think we had the maximum for this year  ?
Maybe

JimboOmega

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Re: The 2017/2018 freezing season
« Reply #903 on: February 16, 2018, 11:34:23 PM »
Couldn't resist this cci-reanalyzer image for Tuesday 20th Feb. Arctic temp anomaly + 6.7 degrees celsius.

But by 26th Feb down to 2 degrees.

It's currently forecasting +6.9C on the 20th with a nowcast of +6...

Kind of crazy how it crashes down to +2 C (which seems so low these days...)

A-Team

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Re: The 2017/2018 freezing season
« Reply #904 on: February 17, 2018, 12:45:53 AM »
RASM-ESRL is back making forecasts after a two-week hiatus. Here is the ice thickness forecast two days out, to 20 Feb 18.

https://www.esrl.noaa.gov/psd/forecasts/seaice/

Technical note: the algorithm may have seen an improvement. Some of the graphics problems remain. This one was mis-scaled and too busy in colors. The animation gradually consolidates colors to simplify the view. The initial state on the 15th should agree with SMOS thinness and Ascat brightness but probably not. Cryosat is the only current source of observational thickness but it does not offer daily coverage. These latter resources do not make forecasts.
« Last Edit: February 17, 2018, 03:35:40 AM by A-Team »

Koop in VA

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Re: The 2017/2018 freezing season
« Reply #905 on: February 17, 2018, 03:41:51 AM »
You think we had the maximum for this year  ?

It's difficult to see how this would be the case.  The periphery seas are likely not in play for several months.  So ESS, Beaufort, Laptev, CAA, Hudson, even Chukchi are not going to go down in any meaningful manner.  So that leaves the focus on Bering, Barents, Okhotsk and Kara.

Bering is at record low for this time and is likely to rebound some (despite the 10 day forecast).  So any surge in Bering needs to be offset by declines in the other 3 to have a chance at the max already being achieved.  This is unlikely (to my lurker way of thinking).  Further, we need to consider the odds of when the maximum is typically achieved.  To have the maximum at this stage (a full month or more than is typical) would statistically have a very low probability.

So while this has been a weird/anomolous freezing season, the likelihood of already reaching the max is exceedingly low, in my layman's opinion.

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #906 on: February 17, 2018, 06:05:07 AM »
You think we had the maximum for this year  ?

No, I don't think so, just hoping since I'm starting to worry I don't see the times when people realise Earth is used up, and start to fight over dwindling resources by manufacturing claims of WMDs in some obscure countries that have had a decent harvest. Mind you, I want to die soon after this.
« Last Edit: February 17, 2018, 06:11:34 AM by Pmt111500 »
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El Cid

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Re: The 2017/2018 freezing season
« Reply #907 on: February 17, 2018, 09:13:06 AM »
You think we had the maximum for this year  ?

Mind you, I want to die soon after this.

Although the loss off arctic ice is now a fait accompli , there is no need to get overly pessimistic. Humanity is very adaptable and will easily survive the consequences. So, I think you can put off your dying  ;)


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Re: The 2017/2018 freezing season
« Reply #908 on: February 17, 2018, 10:20:24 AM »
You can't adapt to starvation due to global crop failures, pandemics due to weakened immune systems among the population, and you can't adapt to temperatures above your ability to lose metabolic heat.

I agree, I want out before that comes to pass.  As unpollyannish as that may be.
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Wherestheice

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Re: The 2017/2018 freezing season
« Reply #909 on: February 17, 2018, 10:30:18 AM »


Humans are very adaptable. The rest of the life on earth.... idk.... they will probably die..... leading to our eventual demise
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jdallen

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Re: The 2017/2018 freezing season
« Reply #910 on: February 17, 2018, 10:49:00 AM »


Humans are very adaptable. The rest of the life on earth.... idk.... they will probably die..... leading to our eventual demise
While as willing as any to bemoan future dark outcomes, can we please take this thread to consequences, eh?
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Pmt111500

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Re: The 2017/2018 freezing season
« Reply #911 on: February 17, 2018, 11:53:54 AM »


Humans are very adaptable. The rest of the life on earth.... idk.... they will probably die..... leading to our eventual demise
While as willing as any to bemoan future dark outcomes, can we please take this thread to consequences, eh?

Well... Yeah. It could be some future Gandhi reads these notes and gets discouraged if the main thread is all doom and gloom. Sorry for off topic.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #912 on: February 17, 2018, 01:12:57 PM »
Here are ice and snow thickness from the refreshed ESRL site and Ascat radar backscatter brightness for 16 Feb 2018. Note the snow is barely ankle deep -- reflective perhaps but not much of a thermal blanket.

This is one of the few ice thickness products that is able to see the chain of thick floes circling off the CAA into the Beaufort and Chukchi. SMOS is really struggling to see this region and Piomas has not a clue. These floes are in rapid motion to the west and so are washed out by any method (like CryoSat) that averages.

Technical note: it's not clear what is causing the 'pole hole' artifact in the ice thickness file. The two ESRL images are oriented at -175º, 85ºN, horizon 20º for better use of image space, rather than our usual Greenland down, pole-centric view. The Ascat image, which has no lat,lon markings or land mask, is similarly oriented but the center and horizon are slightly off.

https://www.esrl.noaa.gov/psd/forecasts/seaice/
ftp://ftp1.esrl.noaa.gov/RASM-ESRL/ModelOutput/RASM-ESRL_4UAF_ICE_2018-02-16.nc
« Last Edit: February 17, 2018, 01:35:58 PM by A-Team »

Apocalypse4Real

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Re: The 2017/2018 freezing season
« Reply #913 on: February 17, 2018, 03:20:23 PM »
A Team - Your imagery expertise is very appreciated. The lack of snow sets up a melting situation in the next few months, and large areas of less than a meter ice creates a summer/fall potential for large areas of open water. This will be an interesting melting season.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #914 on: February 17, 2018, 03:36:44 PM »


Humans are very adaptable. The rest of the life on earth.... idk.... they will probably die..... leading to our eventual demise
While as willing as any to bemoan future dark outcomes, can we please take this thread to consequences, eh?

Thank you. There are over 1800 topics on this wonderful blog. This topic is about this freeze season. In the winter, the consequences topics are highly energetic and worth the visit.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #915 on: February 17, 2018, 03:42:14 PM »
A Team - Your imagery expertise is very appreciated. The lack of snow sets up a melting situation in the next few months, and large areas of less than a meter ice creates a summer/fall potential for large areas of open water. This will be an interesting melting season.

If we have a sunny arctic summer, this is a disaster with so much ice under 1.5 meters and very little time left to thicken.

liefde

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Re: The 2017/2018 freezing season
« Reply #916 on: February 17, 2018, 04:10:32 PM »
Is it just me or do 2017 and 2018 seem to have their "breathing" synchronized? ie if you kinda squint your eyes, they expand and contract roughly at the same times. I would have thought that would be uncorrelated on daily or weekly time scales.
I thought I was the only one seeing that. It seems there's at least some kind of new equilibrium that sort of came to life around October 2016. The interesting detail around that shift is that it started precisely when the QBO went off-base: https://twitter.com/splillo/status/818959727036104705/photo/1 Perhaps the jetstreams and ocean currents have changed to a new state, or the next stepping stone to an ice-free planet.

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Re: The 2017/2018 freezing season
« Reply #917 on: February 17, 2018, 04:29:32 PM »
Is it just me or do 2017 and 2018 seem to have their "breathing" synchronized? ie if you kinda squint your eyes, they expand and contract roughly at the same times. I would have thought that would be uncorrelated on daily or weekly time scales.
I thought I was the only one seeing that. It seems there's at least some kind of new equilibrium that sort of came to life around October 2016. The interesting detail around that shift is that it started precisely when the QBO went off-base: https://twitter.com/splillo/status/818959727036104705/photo/1 Perhaps the jetstreams and ocean currents have changed to a new state, or the next stepping stone to an ice-free planet.
Today I was looking back at Global Sea Ice Extent, I quote from my post

Quote
JAXA's graph for global extent since 1978... tells me is how for many years extent was in a tight pack. The bottom two lines are 2017 and 2018. So much farther apart from the pack. This separation started in October 2016 and has never really stopped.

And in October 2016 it was Antarctic Sea Ice that started the rot. Coincidence?
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uniquorn

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Re: The 2017/2018 freezing season
« Reply #918 on: February 17, 2018, 05:20:17 PM »
Bering is at record low for this time and is likely to rebound some (despite the 10 day forecast). 

I hope it does.
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bbr2314

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Re: The 2017/2018 freezing season
« Reply #919 on: February 17, 2018, 05:34:39 PM »
It isn't going to be rebounding with weather imminent like this...





If anything we should see a rapid retreat through day 3-4-5.

CalamityCountdown

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Re: The 2017/2018 freezing season
« Reply #920 on: February 17, 2018, 06:56:48 PM »
If only using 2 specific data sources, I think a case could be made that the winter maximum may have been reached. Using: 1) the NSIDC five day average chart, and looking specifically at yellow trend line (2015), a year in which the maximum came early, and 2) factoring in the anomalously warm weather in the near term temperature forecast,  then it seems feasible. However, given the record amount of open water and the fact that the daily extent numbers have already started bouncing back from the low on 2/14, it seems vastly more likely that there will be at least one more upward spike in extent during this freezing season, and that I am using "denier" methods to come to a conclusion that the maximum had been reached

jdallen

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Re: The 2017/2018 freezing season
« Reply #921 on: February 17, 2018, 08:53:13 PM »
It isn't going to be rebounding with weather imminent like this...
If anything we should see a rapid retreat through day 3-4-5.
No, it is not, I concur.

Add to that, persistent 40-60KPH winds at the surface in the Bering over this time stretch to churn up the water and generate waves, I would be surprised if we lost half the current extent in the Bering this week.
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jdallen

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Re: The 2017/2018 freezing season
« Reply #922 on: February 17, 2018, 09:14:41 PM »
Thinking about that forecast, watching the GFS SLP model advance right now, I'm struck by something I'm seeing.

There is what in essence is a locus centered over the Sea of Okhotsk, around which low pressure systems are being spawned.  Effectively, it's a truncated cyclone cannon - maybe call it a cyclone shotgun - that shows constant and occasional  fairly deep lows - 970-975mb, sometimes lower - spawning NE of Hokaido and spinning up into the Bering.  There are 6 or 7 over the next 200 hours in the run. 

Even considering the rapidly decaying skill of the prediction at the bleeding edge of the time frame, I think we can still draw the conclusion that a persistent pattern is present, and may continue well past the time there is any chance for good freezing conditions to return.

The timing of this is really bad for any sort of recovery in the Bering and Chukchi.  It also doesn't bode well for the Beaufort and eastern portions of the ESS.
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #923 on: February 17, 2018, 09:24:48 PM »
If only using 2 specific data sources, I think a case could be made that the winter maximum may have been reached.
NSIDC daily data:- An early maximum sometimes does not mean much. In 2015 the maximum was reached on 22nd February. 29 days later, extent had reduced by a paltry 41 k. As of 16th Feb, 2018 is 420k less than 2017 on that date, which I guess is significant, given that 2017 ended up with a record low maximum.
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bbr2314

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Re: The 2017/2018 freezing season
« Reply #924 on: February 17, 2018, 10:43:21 PM »
Thinking about that forecast, watching the GFS SLP model advance right now, I'm struck by something I'm seeing.

There is what in essence is a locus centered over the Sea of Okhotsk, around which low pressure systems are being spawned.  Effectively, it's a truncated cyclone cannon - maybe call it a cyclone shotgun - that shows constant and occasional  fairly deep lows - 970-975mb, sometimes lower - spawning NE of Hokaido and spinning up into the Bering.  There are 6 or 7 over the next 200 hours in the run. 

Even considering the rapidly decaying skill of the prediction at the bleeding edge of the time frame, I think we can still draw the conclusion that a persistent pattern is present, and may continue well past the time there is any chance for good freezing conditions to return.

The timing of this is really bad for any sort of recovery in the Bering and Chukchi.  It also doesn't bode well for the Beaufort and eastern portions of the ESS.
You are correct, but I believe part of the reason for what is unfolding is the unique situation evolving in 2018, where shore-bound sea ice is almost completely absent on the southern side of Russia's Bering Sea coastline.

This has been a unique feature that has only ever happened this year.

The lack of sea ice development in this particular region over the winter is acting in sync with the generous sea ice coverage in Okhotsk and the ice along Alaska's south shore to funnel large amounts of warm salty Pacific water into the Arctic itself. E.G., the contrast between the ice-free and ice-covered regions is what is driving this worsening anomaly.

Hopefully ^ makes sense? In any case, it is probably only going to get worse through March, as the imported Pacific water is going to be increasingly difficult to freeze with the sun now rising higher and higher.

bbr2314

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Re: The 2017/2018 freezing season
« Reply #925 on: February 17, 2018, 10:49:13 PM »
Please see attached which illustrates our new predicament --


Neven

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Re: The 2017/2018 freezing season
« Reply #926 on: February 17, 2018, 11:25:12 PM »
Here are ice and snow thickness from the refreshed ESRL site and Ascat radar backscatter brightness for 16 Feb 2018. Note the snow is barely ankle deep -- reflective perhaps but not much of a thermal blanket.

Doesn't this imply the ice should be much thicker?
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bbr2314

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Re: The 2017/2018 freezing season
« Reply #927 on: February 17, 2018, 11:29:29 PM »
"Bering Sea Ice Doom" has officially made it within aerial range of DMI, projected as of 2/22!




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Re: The 2017/2018 freezing season
« Reply #928 on: February 17, 2018, 11:55:55 PM »
Lincoln Sea is breaking up even more - so much for the ice bridge.  :o  Well I guess the ice bridge could set up before the freezing season is done? Maybe with some of the nearby larger floes interlocking closer to the Nares, but i wouldn't bet on it. Also in the eastern Lincoln sea, along the shore of northern Greenland, ice is breaking free which is unusual since this ice is typically more consolidated/compacted and land-fasted.

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Re: The 2017/2018 freezing season
« Reply #929 on: February 18, 2018, 04:31:13 AM »
FAB ;D(2) appears to be very close to 100 days of existence, which was my prediction ~ 40+ days ago.... much like my posts, nurse-maiding FAB ;D(1) to its record breaking 230+ days of existence from latter 2016 to deep into 2017.
It appears FAB ;D(2) may continue well past 100 days of existence. Strong warm fronts are developing & will envelope Greenland & Canadian Arctic Archipelago & appear to pump heat into the High Arctic. These warm fronts continue to suppress  the long term cold front over Canada, to the south. The continuing north Siberian cold front is bordered by higher latitude warm fronts, both in eastern & western Siberia.
//////
Don't worry. I won't post too often, taking away from the better science you posters present. But I wanted you to know that some oppose the AGW deniers in other ways too.   
     litesong wrote: After 3 weeks this vast system of similar temperature still exists.....the system no longer extends to the U.S. border, & withdraws to the higher latitudes of Canada. Tho still heavy on Greenland, the system is sporadically thinned in the High Arctic, affected by FAB 8)(2) which is still at 12degC above its normal average. The system also, has become spotty in its southern latitudes over Asia.
 FAB 8)(2), which is defined CONTINUOUS excess AGW temperatures above the 80th parallel, now has extended to almost 195 straight days. Soon FAB 8)(2) will have extended its life to 5 TIMES the straight days of over-temperature days occurring in late 1950's & early 1960's. It does appear that FAB 8)(2) will reach 200 days of STRAIGHT existence, the second time since 2015, that High Arctic temperatures have extended for 200 STRAIGHT DAYS OF EXISTENCE. Previous to 2015, back to the late 1950's, NO 200 DAY PERIODS of over-temperature STRAIGHT DAYS have occurred over the entire High Arctic. Even, 100 STRAIGHT DAY PERIODS of over-temperatures were very rare & ONLY IN THE LATTER PORTION OF THE PERIOD MENTIONED.

bbr2314

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Re: The 2017/2018 freezing season
« Reply #930 on: February 18, 2018, 05:19:10 AM »
00z GFS continues theme of possible end to freezing season... wow...

First from Pacific...



And then an even larger pulse of heat from the ATL...



If models are correct it seems we may be in for a repeat of the massive cyclone only a week or two ago...



The net impact is impossible to gauge from so many days out, but it seems quite possible that both the main ATL and PAC fronts will see substantial melt through the end of the month. Perhaps Okhotsk, Labrador, and Kara will be resilient & cold enough to counter... but perhaps not?

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Re: The 2017/2018 freezing season
« Reply #931 on: February 18, 2018, 08:35:01 AM »
I don't see the problem so much as potentially melt-through as much as I see it as too much heat present at a very critical juncture in the refreeze season, where last year ice which had been thin - less than 1.5 meters across much of the basin - was able to recover between 50-75CM of growth between the end of January and early April.  I don't see that happening this year.

A-Team's report of a much thinner snow pack on the ice also portends more rapid acceleration of the melt season than the last two years as well.

After the equinox, I think we need to be watching both albedo and snow depth very closely.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #932 on: February 18, 2018, 12:43:15 PM »
Quote
a much thinner snow pack implies  the ice should be much thicker?... after the equinox watch both albedo and snow depth very closely.
Snow depth and snow properties are factually problematic in my view. Nobody is out there nine months a year; the buoys are missing or inoperative. It is very rare to even have a one-time observational transect in fall, winter or spring. Lines don't provide areal coverage yet the Arctic Ocean is vast and has regionally diverse and rapidly changing weather and winds. So what sort of Dec-Jan-Feb field calibrations exist for satellite sensors producing these snow depth products?

Because of the data hiatus and algorithm update with RASM-ESRL, it's not clear that new snow depth netCDFs are 'backwards compatible' with earlier. So there's no depth comparisons for a while. But yes, it's worth following from here on out as they have albedo, rain and melt pond products too. I could equally envision a big inhibitory effect from a mere dusting of fresh snow just at the start of melt season or a devastating enhancing effect from rain on thicker snow.

Overall it's probably better to focus on the more direct satellite products. The farther along they are in processing, modeling, theorizing, interpolating, interpreting and visualizing, the riskier they become.

Technical note: the last hundred days of ice motion below has new land and water masks that reduce extraneous weather flashing, new day numbering feature that doesn't get buried under the forum mp4 controller, and a 3º lat overlays that provides a scale of 333 km per and also help visualize westward and poleward components of the motion, eg the CAA floe stringer is not moving along a line of constant latitude. The day-label tool is not smart enough to step monthly dates nor merge in a table of frame labels.

Two floe trajectories are shown: one a persistent smooth spot wobbling around near the pole, the other a floe that came off the CAA headed for the Chukchi. The little numbers correspond to rows in the numerical position database, attached below as txt. (ImageJ does all these very conveniently.)

There are enough stable features for 50-60 of these floe trajectories to be drawn. These suffice to for a daily tesselation of the Arctic Ocean when all the vertex-connecting triangles are drawn. A spline fitted to the resulting simplex then has all the attributes of an equation of motion for the ice pack; it is not gridded but rather small plates. It's easy to morph one triangularization into the next, that process takes an Ascat forward with it. However it's hard to see how Ascat's could be generated more than ten days in advance given uncertainty with the wind field.

I also located a firefox plugin that will save out screenshots of whatever is showing when a list of urls is opened in new tabs. These then drag-n-drop into readily animations for ImageJ which can be saved as gifs or mp4s, for example of nullschool weather at its 4 hour frame rate. https://addons.mozilla.org/en-US/firefox/addon/grab-them-all/

It looks like keeping mp4's at 660 pixel width or below defeats the forum's inclination to display them at 720 (one of a few default sizes). The issue here is not avoiding multiple rounds of rescaling that degrade image quality.
« Last Edit: February 18, 2018, 07:53:50 PM by A-Team »

Gray-Wolf

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Re: The 2017/2018 freezing season
« Reply #933 on: February 18, 2018, 12:55:28 PM »
Should we worry about Low solar and its habit of driving high pressure across the north ( even if mainly over winter?)?

The last time we descended into low solar we saw 07' , 2010 and , as sunspot numbers were on the up ,2012?

With us facing some possible northern blocking , over the atlantic side of the basin, from the ongoing SSW I wondering if we will see a runaway start to the season with HP domination the Atlantic side of the basin? If we see the Beaufort high join in the fun then we could see a high melt pond start to the season , a start not seen since the last low end of the sunspot cycle?
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DrTskoul

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Re: The 2017/2018 freezing season
« Reply #934 on: February 18, 2018, 01:06:39 PM »
Should we worry about Low solar and its habit of driving high pressure across the north ( even if mainly over winter?)?

The last time we descended into low solar we saw 07' , 2010 and , as sunspot numbers were on the up ,2012?

With us facing some possible northern blocking , over the atlantic side of the basin, from the ongoing SSW I wondering if we will see a runaway start to the season with HP domination the Atlantic side of the basin? If we see the Beaufort high join in the fun then we could see a high melt pond start to the season , a start not seen since the last low end of the sunspot cycle?

Only problem: low solar affected the weather in such magnitude previously because its contribution was similar magnitude as the background noise. Nowadays the GHG signal is so much higher. Next solar low will be uneventful...

romett1

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Re: The 2017/2018 freezing season
« Reply #935 on: February 18, 2018, 03:00:36 PM »
Pacific side - Feb 06 and Feb 14 - 17. No surprises here. Images: ftp://ftp-projects.cen.uni-hamburg.de/seaice/AMSR2/

numerobis

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Re: The 2017/2018 freezing season
« Reply #936 on: February 18, 2018, 03:11:03 PM »
A-team: How will regional weather variations change the physics of snow depth measurements?

There’s people in the Arctic year round, including researchers.

pileus

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Re: The 2017/2018 freezing season
« Reply #937 on: February 18, 2018, 03:12:52 PM »

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #938 on: February 18, 2018, 03:59:20 PM »
In that image in the previous post, note 2012, which posted a really high and late maximum all over. Not a good starting gate on which to launch a record low minimum.
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Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #939 on: February 18, 2018, 04:01:45 PM »


After the equinox, I think we need to be watching both albedo and snow depth very closely.

Yep.

Warmer, cloudy, wet winters are becoming the new norm for the Arctic. Let's hope we get a repeat of cool, cloudy this summer.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #940 on: February 18, 2018, 04:09:20 PM »
A-Team-

Looking at these wonderful Arctic wide visual videos, I am amazed at the mobility of the entire ice pack. Has this always been the case? When we had MYI of many meters thick across the ocean in the 1990's, were certain areas far less mobile?

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #941 on: February 18, 2018, 04:37:54 PM »
A-Team-

Looking at these wonderful Arctic wide visual videos, I am amazed at the mobility of the entire ice pack. Has this always been the case? When we had MYI of many meters thick across the ocean in the 1990's, were certain areas far less mobile?

No A-Team here, but Basically, yes. If by "certain area" you mean the whole Arctic Sea Ice, then mostly yes. In short.
Amateur observations of Sea Ice since 2003.

Shared Humanity

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Re: The 2017/2018 freezing season
« Reply #942 on: February 18, 2018, 05:00:57 PM »
A-Team-

Looking at these wonderful Arctic wide visual videos, I am amazed at the mobility of the entire ice pack. Has this always been the case? When we had MYI of many meters thick across the ocean in the 1990's, were certain areas far less mobile?

No A-Team here, but Basically, yes. If by "certain area" you mean the whole Arctic Sea Ice, then mostly yes. In short.

Many highly informed experts here have explained the Beaufort Gyre, transpolar drift and Fram export and I follow these discussions carefully. If you look at the above animation, with the decimation of the last refuge of truly thick, relatively immobile MYI north of the CAA, it appears as if the entire Arctic Ocean has begun to simply spin clockwise. Were these more regional ice behaviors (Beaufort gyre, transpolar drift, Fram export) simply imposed by this large, stable ice feature north of the CAA and as that has disintegrated, we now see a new behavior that will dominate the Arctic?

Circling the bowl in a manner of speaking.

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #943 on: February 18, 2018, 05:30:36 PM »
I can't say anything for certain. F.e. the tidal movement would be clockwise but how much it and other factors like deeper currents of Atlantic origin contribute to this apparent reworking of Arctic currents/ice flows? Maybe A-team knows better since I haven't kept up with all this but present just sporadic observations and mostly homespun thoughts of all of this.
« Last Edit: February 18, 2018, 05:37:26 PM by Pmt111500 »
Amateur observations of Sea Ice since 2003.

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Re: The 2017/2018 freezing season
« Reply #944 on: February 18, 2018, 07:24:31 PM »
I can't say anything for certain. F.e. the tidal movement would be clockwise but how much it and other factors like deeper currents of Atlantic origin contribute to this apparent reworking of Arctic currents/ice flows? Maybe A-team knows better since I haven't kept up with all this but present just sporadic observations and mostly homespun thoughts of all of this.
You can clearly see in the above animation how the lack of shore-side ice along the southern edge of the Siberian side of the Bering is 100% to blame for the current predicament. If the depicted pattern had occured with ^ present, the ice would have jammed into the Strait & that would have been that, producing some decent thickness in the process. Instead, water now makes its way directly into the Arctic, and the FYI in its path is not tolerating its heat/force with any kind of notable resistance...

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Re: The 2017/2018 freezing season
« Reply #945 on: February 18, 2018, 07:25:01 PM »
That is a 100 day animation and all of the ice is rotating clockwise. I suppose we would need to look at longer animations to see if this were more than transitory.

bbr2314

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Re: The 2017/2018 freezing season
« Reply #946 on: February 18, 2018, 08:02:27 PM »
The next few days are going to bring very dramatic losses if we are already seeing the above animations from current conditions.

By hr 48 it seems rapid melting could even be possible in areas of the Beaufort adjacent to the spreading open water.



By D5, the Bering Heat is more residual (but remains, at least this winter, as seemingly always...) but the push from the Atlantic is making headway into the CAB with blazing temps over the heart of the Pac and a 960-970MB low over the already-wrecked icepack of the Lincoln Sea.



The combination of this should result in a simultaneous retreat of both Bering & ATL ice fronts while export of Lincoln Sea ice is also temporarily boosted through the Nares (which has no ice bridge of any sort). The latter is perhaps the least quantifiable in terms of ongoing impact into spring and summer but would imagine the surplus of thick CAB ice entering the Labrador Sea come May, June, and July will have some practical impact as well.

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Re: The 2017/2018 freezing season
« Reply #947 on: February 18, 2018, 09:20:13 PM »
Quote
That is a 100 day animation and all of the ice is rotating clockwise.
Whoa, back up a ways. The last eight years of Arctic sea ice motion were posted up-forum as a simulcast. There was also a 541 consecutive day mp4. Not all the ice is rotating CW this month, look at the ESAS. During the last storm, the ice surged strongly across the central Arctic in anti-TransPolar Drift direction. No ice has managed to cross the line between the New Siberian Islands and North Pole since May 2017.

Quote
ice is thinner, so more mobile
That seems intuitively sensible but to actually compare different years requires a quantitative measure of mobility. And what might that be?

The ice pack today rarely moves as a rigid unit, ie by translations or rotations. Did it ever? You can browse the OSI SAF archive of two-day displacements but it only goes back to 2016; NSIDC has a much longer series but in non-graphical format.

Here you would want to generate a straight translation and a shearless rotation in Panoply to be sure how these vector fields look in flat-earth projection view. However flipping through hundreds of OSI SAfs doesn't even kick out any plausible candidates.

At the scale of satellite animation data, the 4000 km wide Arctic Ocean is represented by only 440 Ascat pixels, which has the effect of completely smoothing over opening leads, ridges, over-rafted ice, narrow ribbons of land-fast ice and pockets of open water, anything below the size of 9x9 km pixels.

On any given day, at this resolution, the ice pack appears to move and stretch smoothly in response to different local and regional forces acting on it. Features are deformed yet remain recognizable for many months. This is sometimes called viscoelastic deformation even though no balancing restorative force exists as it would for an idealized elastic rubber band, metal spring or rebounding pizza dough.

However that's not to say the ice is not acting back on itself to damp regionally conflicting motions/ Given a stationary cyclonic feature, the pack would like to rotate but is always playing catch-up to moving weather systems, not to mention land boundary conditions acting like the cup of a Couette viscometer. The properties of compressible and incompressible media are very different. While ice area is not strictly conserved, it's quite close on short time scales.

The CAA stringer is speeding up as it extends further to the west. That is, the deformation has been more extreme the farther along the stringer, the outer floes are moving faster causing the stringer to stretch out. Ice already in the Chukchi has to move aside to accommodate the intrusion.

The immense MYI-fringed feature off the Laptev-SZ has also been deforming rapidly westward the last few days. And ice of all origins approaching the Fram speeds up and so extensionally deforms. Meanwhile shapes and distances in the pole region itself are quite stable and features move in unison.

Can time-dependent triangulation of ice deformation, up-forum, lead to an actual mobility metric? Sure, if the intrinsic propensity of ice to deform can be disentangled from possibly systemic variation in wind speed strength and frictional coupling that acts on the ice.

The nice graphic below from @zlabe shows the multi-year seasonal variation of Bering Sea ice, putting this month well into unprecedented anomaly territory. Very warm air foreseen seven days out.

Technical note: Little Diomede in the Bering Strait is at latitude 65.75ºN, Longyearben in Svalbard is diametrically opposite at 78.22ºN so the difference is 24.25 + 11.78º = 36.03 so at 111.67 km per degree latitude on the ellipsoidal earth, the width of the Arctic here is 4023 km. In the archived Ascat view, that measures 440 pixels so each pixel is about 9.1 km on a side. Polar stereographic projection is not quite equal area..
« Last Edit: February 19, 2018, 02:34:35 AM by A-Team »

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Re: The 2017/2018 freezing season
« Reply #948 on: February 18, 2018, 10:57:27 PM »
By hr 48 it seems rapid melting could even be possible in areas of the Beaufort adjacent to the spreading open water.

Those are temperature anomaly maps you're posting. Actual temperatures will barely get above 0 °C.

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bbr2314

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Re: The 2017/2018 freezing season
« Reply #949 on: February 18, 2018, 11:50:05 PM »
By hr 48 it seems rapid melting could even be possible in areas of the Beaufort adjacent to the spreading open water.

Those are temperature anomaly maps you're posting. Actual temperatures will barely get above 0 °C.



Open water is visible and spreading. The action will come in sync with wind and waves. IMO there will be melt over a wide area and come 2/25 the picture over Bering will be substantially more bleak than today.