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meddoc

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Re: The 2017/2018 freezing season
« Reply #850 on: February 12, 2018, 10:17:16 AM »
The Polar Vortex has been completely split in half, the one on the Siberian Side is going to collapse completely, leaving only Northern America & Greenland under its Cover. Only this Half has some Chance of Survival under the still partially Dark Arctic. The Rest of the Cold will be gone and be missing big- time in Spring - Summer.

https://earth.nullschool.net/#current/wind/isobaric/70hPa/orthographic=-1.00,80.99,304/loc=92.110,81.277


subgeometer

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Re: The 2017/2018 freezing season
« Reply #851 on: February 12, 2018, 10:38:52 AM »
GFS doesn't show any sign of cold in the Bering over the next ten days, nor on the Atlantic front. The Sea of Okhotsk and Baffin Bay are both much colder, and any extent growth is likely to be in those irrelevant regions

DavidR

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Re: The 2017/2018 freezing season
« Reply #852 on: February 12, 2018, 11:23:17 AM »
Interesting to see that Andrew Slaters predictions for this year have just  started coming in and his methodology is predicting a NSIDC extent of 13.62M km^2 for the 2nd of April.  That's a massive 500K km^2 below the current record for that day.

http://cires1.colorado.edu/~aslater/SEAICE/

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Neven

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Re: The 2017/2018 freezing season
« Reply #853 on: February 12, 2018, 01:34:28 PM »
Interesting to see that Andrew Slaters predictions for this year have just  started coming in and his methodology is predicting a NSIDC extent of 13.62M km^2 for the 2nd of April.  That's a massive 500K km^2 below the current record for that day.

http://cires1.colorado.edu/~aslater/SEAICE/

Andrew Slater is no longer alive, so is this graph produced automatically or has someone at NSIDC taken this task on him/her?
Compare, compare, compare

DavidR

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Re: The 2017/2018 freezing season
« Reply #854 on: February 12, 2018, 01:47:19 PM »
Andrew Slater is no longer alive, so is this graph produced automatically or has someone at NSIDC taken this task on him/her?

There is no information on the website however this is one of the few graphs that is updating so I suspect it has been automated somehow.
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #855 on: February 12, 2018, 02:32:24 PM »
The stratospheric polar vortex was colder than normal before this split, while at the surface the Arctic and both the north Atlantic and north Pacific were warmer than normal. This split will speed up the processes that happen in the spring months. Tropospheric winds will speed up at the midlatitudes as spin moves outwards from the polar region.

This won't be like January 2013 because the polar vortex won't have time to recover in the following month. February 2013 was perfect for sea ice recovery because there was a huge high pressure area parked over the pole for the whole month. With clear dark skies and subsidence, enormous amounts of heat radiated out to space.

That won't happen this time because the sun is already rising on the north slope of Alaska.

Moreover, with the predicted displacement pattern, high pressure will set up over northern Siberia and pressure will be relatively low on the American side. This means there will likely be a dipole with more storms and heat entering the Arctic from the Atlantic.

Correction & addendum: I won't delete what I just wrote but the latest CFSv2 run predicts high pressure over most of the Arctic with a solid Beaufort high in March. If it's correct, March will be a good month for sea ice volume recovery in the high Arctic. However, winds will be favorable for Fram export and import of Pacific water through the Bering strait if the forecast verifies.

« Last Edit: February 12, 2018, 03:20:12 PM by FishOutofWater »

A-Team

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Re: The 2017/2018 freezing season
« Reply #856 on: February 12, 2018, 03:42:07 PM »
Here is Fram export since Jan 1st, with five days of GFS wind forecast out to Feb 17th. Export of ice between Morris Jesup and the pole has picked up the last couple of days. Ice export out the Fram depends not only on wind and pick-up by the East Greenland Current but also on forcings from remote motions of the ice pack. There is seldom any back-pressure from islands or ice along the Svalbard line.

This area sees the sun about a month later than the Beaufort-Chukchi-ESAS ice, around March 5th. Note Wrangel Island is within the sunlit zone already. The sun is too low and weak to be melting ice but is enough to be affecting the air column.

Technical notes: To see sunlit areas change by date, set Worldview on a visible wavelength satellite and scroll older 2017 dates. Sunrise times are the same every year.

To build a final pause into mp4 images, copy the last frame and use the concatenate feature in ImageJ to give five duplications. The codecs might remove stationary frames but the ones used do not. Here the near-real time data products had to pause at yesterday whereas the GFS wind could continue on five days of forecast.

To make nullschool animations over a given date range, arrange the view, then vary the date and time using mail-merge from a simple spreadsheet into a link like the one below, open all the resulting urls in new tabs using web browser plugin like 'Bulk URL Opener', save out whole window screenshots as layers in ImageJ or Gimp (as 'Save image as...' won't work), then crop and resize to forum limits, retaining the data in the green circle.

https://earth.nullschool.net/#2018/02/13/1200Z/wind/isobaric/1000hPa/overlay=temp/stereographic=-45.00,90.00,2259/loc=14.000,85.000
« Last Edit: February 12, 2018, 08:54:25 PM by A-Team »

Peter Ellis

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Re: The 2017/2018 freezing season
« Reply #857 on: February 12, 2018, 05:21:28 PM »
Basically what happened with these buoys is they melted out in September and then the pack consolidated and froze them back in a few weeks later. However the ice never achieved any free-board...

How can you tell freeboard from IMB data - it doesn't show sea level. The initial zero point is the top surface of the ice as and when the buoy was placed. At that point, the water levelwould have been at around -20cm, since 20cm freeboard is what you'd expect for a floe that's 1.7 metres thick.

As the ice thickened from below, note that the buoy remained frozen in place, so the zero point (ice surface) doesn't change even as the floe thickens and rides higher in the water.  Conversely, when top melt starts, the ice surface goes down relative to the buoy, reaching about -25cm in early August.  This doesn't mean the floe was underwater at that point - as the surface layers melt away, the remainder of the floe will inevitably have risen in the water by simply physics.

When the buoy melted free in September it will have bobbed freely in the hole (giving unstable readings) until it re-froze.  After re-freeze, the new zero is at an arbitrary point depending on how the buoy happens to have ended up relative to the ice surface. Once it freezes in place, that resets a new zero level at the (new) ice surface, which then remains fixed even as snow accumulates above.

Crucially, you have no data as to the water level, and thus cannot tell what the freeboard is, whether the floe is submerged, or any such conjecture.



Edit:  Also, why are you blithering about data "censorship" from the two other buoys? They were placed in September, but so far there's been no output from them (except maybe GPS? There's a supposedly "current" position from early December...).  Possibly they were dead on arrival and they're just not giving data.  Maybe they weren't designed to generate data during the winter, but they're conserving battery power so as to give accurate data once they start receiving sunlight in the spring.  We just don't know, and leaping to accusations of censorship is plain ridiculous.
« Last Edit: February 12, 2018, 05:27:11 PM by Peter Ellis »

jdallen

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Re: The 2017/2018 freezing season
« Reply #858 on: February 12, 2018, 09:34:09 PM »
<snippage>
Correction & addendum: I won't delete what I just wrote but the latest CFSv2 run predicts high pressure over most of the Arctic with a solid Beaufort high in March. If it's correct, March will be a good month for sea ice volume recovery in the high Arctic. However, winds will be favorable for Fram export and import of Pacific water through the Bering strait if the forecast verifies.
That's still a mixed blessing, as high pressure means the clear skies will also be passing through increasing insolation as we run up to the equinox.

This won't be impactful over the central basin, but as you point out, the sun has risen on the North Slope, so the Bering, Beaufort and Chukchi will also be seeing the net energy equation shifting back against the ice.

Even with a high getting established, I'm not hopeful that the ice on the Atlantic side will have time to recover especially; there's too much open water, and to much heat already in place, and I expect we will still see storms and imported moisture running up to the margins of the basin, as well as running through the Barentsz and Kara seas.
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #859 on: February 13, 2018, 03:24:31 AM »
Agreed, JD a mixed blessing and we can't expect the models to get this unprecedented PV disruption right. According to Judah Cohen this event involved a record poleward heat transport across the 100mb surface - heat transferred from the troposphere to the stratosphere.

His blog post today was very informative.
https://www.aer.com/science-research/climate-weather/arctic-oscillation/

Pavel

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Re: The 2017/2018 freezing season
« Reply #860 on: February 13, 2018, 10:31:14 AM »
The Bering sea looks essentially ice-free comparatively with the last year's mild winter

2phil4u

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Re: The 2017/2018 freezing season
« Reply #861 on: February 13, 2018, 12:36:05 PM »
I recognize and i became more extreme that the very end of the NAO, the island called "Spitzbergen" in germany.
In the 60 ice was even south of this island.
The border is not changing this much over the year like in other areas, just because there is a warm water flow.
but if you look now there is really no ice, it fails like 200km.
this is interesting because some say that the warm water from south slowed down but here we have like the area where water falls to the ground wandered to the north.



At DMI you see, that salinity is high, like water got more and more salty over the last decades and the temperature is still between 0-2 degree at near N80 and up to 6 degree in the south !!!





But it looks like it is just to late, water still gets colder but winter isnt long enouph to freeze the region, that was never ice free until the last years.


« Last Edit: February 13, 2018, 12:48:34 PM by 2phil4u »

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #862 on: February 13, 2018, 03:26:05 PM »
phil, that salty water on the Atlantic side won't freeze because there's warm salty water under it. That's why the term "Atlantification" was coined. The only way to get ice on over that warm salty water now is to force it over by winds and ice pack motion.

Those salinity maps are consistent with Mercator ocean maps which show warm Atlantic water moving into the Arctic seas at depth.

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #863 on: February 13, 2018, 05:04:02 PM »
From being very undecided yesterday, the Climate Prediction Center has grown more certain of a distinctly negative AO index as we head towards the end of February.

Some of the members go as low as -5 and -6, which would be very low indeed.


jdallen

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Re: The 2017/2018 freezing season
« Reply #864 on: February 13, 2018, 05:52:33 PM »
From being very undecided yesterday, the Climate Prediction Center has grown more certain of a distinctly negative AO index as we head towards the end of February.

Some of the members go as low as -5 and -6, which would be very low indeed.
... and presages major chaos in circulation with blowouts of arctic air south and intrusions of heat and moisture north. Record late winter snowstorms, anyone? Deepfreezes in the lower Mississippi valley? 30C positive temp anomalies north of 80? Rain in the Kara?  All possible.
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Cid_Yama

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Re: The 2017/2018 freezing season
« Reply #865 on: February 13, 2018, 11:15:12 PM »

numerobis

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Re: The 2017/2018 freezing season
« Reply #866 on: February 13, 2018, 11:32:02 PM »
Temperature is shooting up 8 degrees in south Baffin! From highs of -38 to highs of -30 (and even warmer tomorrow).

bbr2314

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Re: The 2017/2018 freezing season
« Reply #867 on: February 14, 2018, 06:10:36 AM »
It appears the freezing season is now over for the Bering. The GFS and especially CMC show a firehose of warmth and moisture that leads to repeated intrusions of +0C air through D10.

Ice has already been retreating, it seems this may accelerate.

While the melt season may be starting across the Bering and perhaps the ATL front, it seems that freezing will continue in Okhotsk/Labrador/Barents, which may pencil out to small additional gains in area and extent, and that could also mask the severity of the Chuchki/Bering problem through to early June. But once all the FYI that's going to melt out anyways does exactly that...

Combined with the lack of snowcover relative to last year, it seems like the warmth is winning out over the cold this spring. 2017 without its snowcover could've well been substantially worse than 2012, and given the Pacific this year, we may be heading for a situation as bad or worse.

bbr2314

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Re: The 2017/2018 freezing season
« Reply #868 on: February 14, 2018, 06:49:07 AM »
Also --

SST/SSS maps show that it appears the West Greenland Current may have shut down, either mostly or completely. Ice has advanced well past the front of any other recent year in the Labrador Sea as a result. This may continue into March if the flow of freshwater from the NW & resilient weather pattern keeps up unabated (and that seems quite possible).

It seems as though the Irminger Current may have superseded the WGC? It looks like it normally/used to run underneath the WGC, with the WGC buffered by the sea ice adjacent to SE Greenland.

Perhaps the lack of ^ as a buffer has allowed substantially more saline waters to intrude along Greenland's SE shore (as SSS comparison maps indicate), in turn degrading the EGC/WGC, and in turn allowing the Irminger Current to supersede them both, interacting with the displaced freshwater from the dislodged Beaufort Gyre in a very new and novel way?
« Last Edit: February 14, 2018, 07:06:03 AM by bbr2314 »

meddoc

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Re: The 2017/2018 freezing season
« Reply #869 on: February 14, 2018, 08:28:45 AM »
The Polar Vortex at 10 & 70 mb will collapse the coming Days. Centered over Labrador, the only System will survive- further convincing Whmericans- there's no such Thing as Global Warming.

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #870 on: February 14, 2018, 11:29:07 AM »
Interesting to see that Andrew Slaters predictions for this year have just  started coming in and his methodology is predicting a NSIDC extent of 13.62M km^2 for the 2nd of April.  That's a massive 500K km^2 below the current record for that day.

http://cires1.colorado.edu/~aslater/SEAICE/

April 2nd? That would make it the latest day for the maximum in the satellite record ? - and therefore means both an amazingly low extent gain for a very long period until then, and on the other hand a a very late start to the melting season. The assumptions behind the graph would be fascinating - and here they are

Quote
What are these plots?

These are probabilistic projections of sea ice extent. I use a very simple regression/projection method based on prior years and assimilation of the latest data - it's not the most sophisticated method but it does have a fair degree of skill.

The timeseries plot is compiled from many individual daily forecasts. The Forecast is based on Slater (2014) and Anomaly Persistence uses data from 1988-2013 as the mean state. The forecast timeseries are not a single forecast from a timestepping model! Each day a forecast is made for 50 days ahead and this point is added to the plotted timeseries.

The quantity being forecast is the NASA-Team data, which is different from the official NSIDC values (partly due to the "pole hole").

Remember that there is no single correct answer; colors show expected probabilities only. One way to think about the plot is that for the area that shows 80% probability of being ice covered on the forecast date, 20% of that area is expected to be ice free. Do not mistake the blue colored areas as being a simplified extent forecast.

The projected probabilities can also contain error. For example, in August and September, the projections are overconfident at the mid-range probability levels. In hindcast simulations (2005-2011), where the projections expected there to be ice 50% of the time, ice was only present 40% of the time; that's a non-trivial error. Reliability is computed for days within a given month over the whole period indicated (2005-2012); individual days may do better or worse. Some months do better than others.

Forecasts (actually, hindcasts!) for prior years are also shown, along with the observed sea ice extent for the forecast day so you can see the skill/failure of the method.

The images should update around 9am Colorado time each day.

What Data is used?
NASA-Team data is used, both the archive and the near-real-time. Many "behind the scenes" people at NSIDC do a great job keeping this data up-to-date, available and well documented.


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lurkalot

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Re: The 2017/2018 freezing season
« Reply #871 on: February 14, 2018, 12:07:27 PM »
"April 2nd? That would make it the latest day for the maximum in the satellite record ? - and therefore means both an amazingly low extent gain for a very long period until then, and on the other hand a a very late start to the melting season."

I think you may have misunderstood: Slater is predicting 50 days ahead, so April 2nd was the first date of his prediction not a suggested maximum. To attain that it would have reached a maximum prior to April 2nd and be on its way down again.

DavidR

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Re: The 2017/2018 freezing season
« Reply #872 on: February 14, 2018, 12:57:32 PM »
"April 2nd? That would make it the latest day for the maximum in the satellite record ? - and therefore means both an amazingly low extent gain for a very long period until then, and on the other hand a a very late start to the melting season."

I think you may have misunderstood: Slater is predicting 50 days ahead, so April 2nd was the first date of his prediction not a suggested maximum. To attain that it would have reached a maximum prior to April 2nd and be on its way down again.

 The 2018 minimum extent is already  at  least 13.979( 5 Feb), well above Slater prediction for Apr. 2nd.  Slater is predicting the extent on 2nd April  not the date the maximum occurs.  It  should be noted that the predictions at this state tend to  underestimate the extent in early  April.
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #873 on: February 14, 2018, 01:50:33 PM »

Thanks for setting me straight. When I put my paintbrush down a look at what happened twixt now and April 2nd in previous years might be worth a look ?
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A-Team

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Re: The 2017/2018 freezing season
« Reply #874 on: February 14, 2018, 03:00:15 PM »
Quote
what happened twixt now and April 2nd in previous years might be worth a look
Quite a different configuration of FYI/MYI ice a year ago in the Arctic Ocean. The dark tongues in the upper right are not from the Kara but rather formed in open water along the MYI edge during 2016 freeze-up. The first mp4 shows the next 100 days of last year; the second shows the lead-up this year to today's date. There was a huge loss of thick CAA and central ice during this time frame.

Be aware of the distinction between NH ice and Arctic Ocean ice this time of year; year-on-year variation is geolocated almost entirely in the periphery, NH-AO.

Technical note: I've not yet determined what is causing the small rectangular artifact with its lower left corner in the pole hole, it looks like a slight multiplicative scaling error in their contrast pipeline. It goes back for years. I've asked NOAA to re-process the Ascat archive to remove it.

It looks like the equation of motion for the entire ice pack can easily be obtained by tessellating floe trajectory positions which can be done directly by the ImageJ 'point' tool. These won't quite give a voronov triangulation and won't always give 100% AO coverage but the resulting elastic mesh does transfer Ascat raster images (~adobe photoshop) into the displacement vector realm (~adobe illustrator) which is far more convenient for gradient, curl and divergence. They do a very similar thing in astronomy where it's called DTFE for delaunay tessellation field estimator. The necessary spreadsheet triangle math was worked out by the babylonians thousands of years ago.
« Last Edit: February 14, 2018, 06:20:59 PM by A-Team »

uniquorn

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Re: The 2017/2018 freezing season
« Reply #875 on: February 14, 2018, 05:08:52 PM »
Good view of the Beaufort yesterday. The ice is quite mobile but clouds obscure an animation.

A-Team

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Re: The 2017/2018 freezing season
« Reply #876 on: February 14, 2018, 05:16:38 PM »
The mp4 below shows Arctic Ocean ice thinness according to UBremen SMOS, 2017 on the left, 2018 on the right. There's a pause on the last available day for 2018 (Feb 13th) but the 2017 continues on to April 15th, perhaps suggesting what 2018 might do. The Bering Strait is in the bottom left corner. The second mp4 chops out the central region to facilitate comparison of the Barents Edge and the Beaufort-Chukchi regions.

Quote
Good view of the Beaufort yesterday. The ice is quite mobile but clouds obscure an animation
The gif rescales Ascat to that of Suomi VIIRS band 15 night brightness. The older thicker rougher ice shows up as bluer/colder. The floe string lines up fairly well but Ascat is not picking up the fracture lines probably because they are too narrow though enough to let ocean heat show which is favorable for band 15.
« Last Edit: February 15, 2018, 03:21:37 PM by A-Team »

oren

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Re: The 2017/2018 freezing season
« Reply #877 on: February 14, 2018, 07:39:58 PM »
The first mp4 shows the next 100 days of last year; the second shows the lead-up this year to today's date. There was a huge loss of thick CAA and central ice during this time frame.
Thanks for all these animations. I am particularly fascinated by the action in the Lincoln Sea. The ASCAT animation shows the thick ice north and west of Kap Morris Jessup being "lifted" up and to the left, at least 3 major times, with chunks of it peeled away to flow down the Nares.
I estimate from the animation that about half of that ice is already gone. To compare, the 2016 animation shows it starting to lose integrity only at the very end of the mp4, in early April, while still retaining its full area.

Tor Bejnar

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Re: The 2017/2018 freezing season
« Reply #878 on: February 14, 2018, 08:27:40 PM »
Oren: as A-Team said to me...
Quote
gif shows about half of the NE Lincoln Sea MYI was actually exported.
Good eye! Blue to pink area ratio below is 46%.
...
{edit of my quoted [not referenced] sentence - the image is A-Team's.}
Arctic ice is healthy for children and other living things.

romett1

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Re: The 2017/2018 freezing season
« Reply #879 on: February 14, 2018, 09:06:27 PM »
It appears the freezing season is now over for the Bering. The GFS and especially CMC show a firehose of warmth and moisture that leads to repeated intrusions of +0C air through D10.
Ice has already been retreating, it seems this may accelerate.
One storm after another is coming towards Bering Sea. Those 25 m/s winds with +3 °C air (Saturday morning) are definitely not too helpful for ice (Earth.nullschool). Interesting to watch how much Chukchi Sea will be affected.

A-Team

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Re: The 2017/2018 freezing season
« Reply #880 on: February 14, 2018, 10:23:02 PM »
Quote
I am particularly fascinated by the action in the Lincoln Sea. The ASCAT animation shows the thick ice north and west of Kap Morris Jessup being "lifted" up and to the left, at least 3 major times, with chunks of it peeled away to flow down the Nares.
That is about the quietest pocket for the ice in the whole Arctic Ocean until it isn't. The ice that is in there now hasn't been there very long ...  attritional episodes seem to add up to complete turnover. But it gets replaced by old thick ice from elsewhere along the CAA or centrally.

Lincoln Sea ice has been the subject of numerous studies because of its relative convenience to the Nord Station, Alert and Thule, even though it does not seem a good representative of AO ice. Nobody would set up a camp out there today though.

Comparison of sea-ice thickness distribution in the Lincoln Sea in 2004 and 2005
C. Haas, S. Hendricks and M. Doble
https://doi.org/10.3189/172756406781811781
14 September 2017

Results of helicopter-borne electromagnetic measurements of total (ice plus Snow) Sea-ice thickness performed in May 2004 and 2005 in the Lincoln Sea and adjacent Arctic Ocean up to 86˚N are presented. Thickness distributions South of 84˚N are dominated by multi-year ice with modal thicknesses of 3.9 m in 2004 and 4.2 m in 2005 (mean thicknesses 4.67 and 5.18 m, respectively). Modal and mean Snow thickness on multi-year ice amounted to 0.18 and 0.30 m in 2004, and 0.28 and 0.35 m in 2005. There are also considerable amounts of 0.9–2.2m thick first-year ice (modal thickness), mostly representing ice formed in the recurring, refrozen Lincoln Polynya.
« Last Edit: February 14, 2018, 10:43:37 PM by A-Team »

subgeometer

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Re: The 2017/2018 freezing season
« Reply #881 on: February 14, 2018, 10:23:30 PM »
From being very undecided yesterday, the Climate Prediction Center has grown more certain of a distinctly negative AO index as we head towards the end of February.

Some of the members go as low as -5 and -6, which would be very low indeed.
... and presages major chaos in circulation with blowouts of arctic air south and intrusions of heat and moisture north. Record late winter snowstorms, anyone? Deepfreezes in the lower Mississippi valley? 30C positive temp anomalies north of 80? Rain in the Kara?  All possible.

The GFS  is/has been showing constant +20C anomalies over the Chukchi sea and its margins right out the end of the forecast. A N Pacific cyclone cannon drives lows into Kamchatka and far eastern Siberia,withe constant southerlies on their western flanks pushing warm air and moisture through the Bering Strait. High pressure dominates the central basin but even that cannot bring the cental arctic down to the average

Cid_Yama

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Re: The 2017/2018 freezing season
« Reply #882 on: February 15, 2018, 12:55:17 AM »
Andrew Slater is dead.  No one has answered the question of what we are seeing.  Has someone taken it over and doing the what needs to be done to maintain the model's connection with reality?  That needs to be answered, because, unattended, it may have already run off the rails.

And could people start referring to it as something different than 'Slater's'.  Obviously, it is no longer him.   

 

DrTskoul

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Re: The 2017/2018 freezing season
« Reply #883 on: February 15, 2018, 05:13:26 AM »
Andrew Slater is dead.  No one has answered the question of what we are seeing.  Has someone taken it over and doing the what needs to be done to maintain the model's connection with reality?  That needs to be answered, because, unattended, it may have already run off the rails.
Y8
And could people start referring to it as something different than 'Slater's'.  Obviously, it is no longer him.   

 

Somebody's model will continue to be named after them, long after their death if successful and useful.
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
― Richard P. Feynman

Tor Bejnar

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Re: The 2017/2018 freezing season
« Reply #884 on: February 15, 2018, 05:15:36 AM »
Slater's 50-day projection is automatic.  I've read others state this this year as well as last year.  He died in 2016.  Think of this as his spirit living on, but I still morn his passing.
Arctic ice is healthy for children and other living things.

John

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Re: The 2017/2018 freezing season
« Reply #885 on: February 15, 2018, 11:21:24 AM »
The mp4 below shows Arctic Ocean ice thinness according to UBremen SMOS, 2017 on the left, 2018 on the right. There's a pause on the last available day for 2018 (Feb 13th) but the 2017 continues on to April 15th,


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.

charles_oil

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Re: The 2017/2018 freezing season
« Reply #886 on: February 15, 2018, 12:13:08 PM »

Cid/ Tor -
I have had some discussion (early 2017) with NSIDC about this page and they were researching it - so its great if its back on track


http://cires1.colorado.edu/~aslater/SEAICE/


I now have asked if they are continuing using the same methodology and if its being kept in this form....

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #887 on: February 15, 2018, 12:44:51 PM »
The mp4 below shows Arctic Ocean ice thinness according to UBremen SMOS, 2017 on the left, 2018 on the right. There's a pause on the last available day for 2018 (Feb 13th) but the 2017 continues on to April 15th,


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 once tried to calculate if there was some sort of lunar synchronicity on the values of ice growth/decrease and found out there was not. It's though still clear that the tidal cracks near coast expand and contract due it. It's just not in same sync everywhere. Add to that the satellites passages over a particular area are not in sync with lunar cycles it's pretty impossible to find out, from observations, if there is a synchrony present. There's quite a lot of room to make hypotheses though. I won't try again, at least from images from orbit.
Amateur observations of Sea Ice since 2003.

John

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Re: The 2017/2018 freezing season
« Reply #888 on: February 15, 2018, 02:45:06 PM »
The mp4 below shows Arctic Ocean ice thinness according to UBremen SMOS, 2017 on the left, 2018 on the right. There's a pause on the last available day for 2018 (Feb 13th) but the 2017 continues on to April 15th,


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 once tried to calculate if there was some sort of lunar synchronicity on the values of ice growth/decrease and found out there was not. It's though still clear that the tidal cracks near coast expand and contract due it. It's just not in same sync everywhere. Add to that the satellites passages over a particular area are not in sync with lunar cycles it's pretty impossible to find out, from observations, if there is a synchrony present. There's quite a lot of room to make hypotheses though. I won't try again, at least from images from orbit.

I'm not sure I see it now, in fact. At the end yes in the bigger movement but not through the shown history. So I'll put it down to a coincidence.

I am more inclined to doubt my eyes in general now that I am working with graphics a lot these days. Amazing what they paint into scenes.

uniquorn

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Re: The 2017/2018 freezing season
« Reply #889 on: February 15, 2018, 03:00:21 PM »
The floe string lines up fairly well but Ascat is not picking up the fracture lines

A closer look at some of those older floes

A-Team

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Re: The 2017/2018 freezing season
« Reply #890 on: February 15, 2018, 04:18:35 PM »
Quote
A closer look at some of those older floes
Nice. Floes can hardly be seen in the visible except by tweaking the contrast. I wonder if those older floes would jump out if driving across on a snowmobile, risky business. Do they make polarized sun goggles? We don't have polarization in satellite imagery except at radar wavelengths.

The mp4 shows the provenance of these big floes.
« Last Edit: February 15, 2018, 05:29:27 PM by A-Team »

oren

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Re: The 2017/2018 freezing season
« Reply #891 on: February 15, 2018, 09:59:28 PM »
I keep wondering in idle speculation about this "wall" of thicker floes stretching into the Beaufort (and Chukchi?).
On the one hand, the wall may serve to slow extent losses around June, as I believe they have in the last two years. Once past the barrier, extent losses went faster than expected. But maybe a delay during peak insolation has saved the central pack from further damage.
On the other hand, if this wall is "breached" early on, there will be little defenses behind. Having a lot of the best ice in far southern waters could end in disaster, especially with the Bering extent as shockingly low as it is.

bbr2314

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Re: The 2017/2018 freezing season
« Reply #892 on: February 15, 2018, 10:39:19 PM »
So that would not be good... D9-10, but nevertheless, not good...


dosibl

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Re: The 2017/2018 freezing season
« Reply #893 on: February 15, 2018, 11:15:39 PM »
The latest d10 forecast on cci is shocking, but since its so far out I'm inclined to wait a few days and see if the models still think that once its closer.

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #894 on: February 16, 2018, 12:23:43 AM »
Has Pettit's NSIDC graph just declared not getting a record low max an outlier?

A-Team

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Re: The 2017/2018 freezing season
« Reply #895 on: February 16, 2018, 12:48:50 AM »
GFS-nullschool next five days suggesting a full trans-polar shear as winds are tugging in opposing directions rather than setting the ice pack in rotation. (Wind sprites are brighter at their leading ends.)

The OSI SAF sea ice drift vectors show regionally specific differential ice velocities quite well, in accord with Ascat image pairs: the blue band of low wind velocity corresponds to a stationary axis of ice motion. Ice within the CAA is solidly frozen and shows no displacement (other than periodic popping up of the block east of Banks Island discussed up-forum).
« Last Edit: February 16, 2018, 07:14:44 PM by A-Team »

A-Team

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Re: The 2017/2018 freezing season
« Reply #896 on: February 16, 2018, 05:02:59 PM »
Here is a comparison of ice thinness on Feb 14th for the last 8 years (from UH SMOS). The Chukchi is in the worst shape this year it has been (though 2016 was also in very poor condition); elsewhere there are patterns but also a lot of variability.
« Last Edit: February 16, 2018, 06:09:12 PM by A-Team »

romett1

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Re: The 2017/2018 freezing season
« Reply #897 on: February 16, 2018, 07:34:52 PM »
Here is a comparison of ice thinness on Feb 14th for the last 8 years (from UH SMOS). The Chukchi is in the worst shape this year it has been (though 2016 was also in very poor condition)
More and more open water over Chukchi Sea (Feb 06 - Feb 14 - Feb 15). Images: ftp://ftp-projects.cen.uni-hamburg.de/seaice/AMSR2/

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #898 on: February 16, 2018, 08:20:18 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.
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Alexander555

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Re: The 2017/2018 freezing season
« Reply #899 on: February 16, 2018, 08:23:56 PM »
You think we had the maximum for this year  ?