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Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #800 on: February 08, 2018, 11:10:57 AM »
The plunge in sea ice concentration poleward ... we'll have to wait and see if those hold up as AMSR2 can display a lot temporary weather artifacts (eg when the center of a cyclone passes over).

It's still looking distinctly dodgy on the latest AMSR2 update. See also Thomas Lavergne's sea ice drift animation:

http://GreatWhiteCon.info/2018/02/the-february-2018-fram-strait-cyclones/#Feb-08
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A-Team

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Re: The 2017/2018 freezing season
« Reply #801 on: February 08, 2018, 12:11:59 PM »
Quote
It's still looking distinctly dodgy on the latest AMSR2 update
There are both conserved ice features and weather artifacts on the AMSR2 3.125 km over the last three days of the storm, in addition to lee polynyas around the islands and lift-off north of SZ. (The mp4 shows heal-and-seal plus passing weather effects for the last 160 days.)

We'll need the Feb 8th and 9th to assess the new damage appearing on the 7th. Which is better done on Sentinel-1AB orbital swaths with time stamps. We're always looking for consilience on the source side.

The question is whether it matters. The damaged ice is mostly poised for Fram export anyway over the next month so won't be around for melt season. The darker tongues originated in late October from the Kara and Laptev and so do not represent export of older thicker central or CAA ice, though there will be more of that this week.

Quote
See also T Lavergne's sea ice drift animation
Those are hosted at OSI SAF; Lavergne's five sea ice motion papers are listed at the bottom link below. They're 48-hour interval ice drift products posted from 2016 to the present. The scaling is 3x literal displacement, purple arrows are nearest neighbor interpolation; the hollow-core arrows seem to denote scale-exceeding. Oceans are colored as closed ice, open ice (good idea) and open water.

That means an arrow extending a full 62.5 km grid cell spacing length corresponds to a drift of 20.8 km or distance between the start point and stop point after 48 hours. These grid points are conveniently built into the map as even 0 velocity gets a point. The two-day thing is a bit awkward on the overlap, eg 04-06 followed by 05-07. The storm overwhelmed the scaling system but we can always fix that in Panoply.

The 2x image is new to 2018. LR-drift means low resolution, SSMIS (91 GHz, DMSP F17), ASCAT (Metop-B), and AMSR-2 (18.7 and 36.5 GHz, GCOM-W1). Extraordinary job of annotating the product, see 3rd link below.

They also offer a medium resolution daily based on 1 km AVHRR channel 2 (Metop-A VIS) and channel 4 (Metop-A TIR). It also is offered as a netCDF, meaning we could easily auto-process the whole set into a single animation as described on DevCorner. We've also made these products here using SIFT etc on ImageJ. Panoply will pull out the velocity distribution, averages, and extremes.

http://osisaf.met.no/p/osisaf_hlprod_qlook.php?year=2018&month=02&day=01&prod=LR-Drift&area=NH&size=100%25

http://osisaf.met.no/p/ice/#mrdrift

http://osisaf.met.no/p/ice/lr_ice_drift.html

ftp://osisaf.met.no/prod/ice/drift_lr/merged/  netCDF archive
« Last Edit: February 09, 2018, 10:45:48 AM by A-Team »

Nightvid Cole

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Re: The 2017/2018 freezing season
« Reply #802 on: February 08, 2018, 04:31:03 PM »
Unfortunately, I can't do images on my computer right now, but take a look at Climate Reanalyzer. The Arctic is ground zero for an absolute blowtorch starting within the next few days!!!!

Neven

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Re: The 2017/2018 freezing season
« Reply #803 on: February 08, 2018, 05:01:45 PM »
Unfortunately, I can't do images on my computer right now, but take a look at Climate Reanalyzer. The Arctic is ground zero for an absolute blowtorch starting within the next few days!!!!

Yes, a 6.4 °C anomaly is quite something. Here's the mp4:

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Alexander555

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Re: The 2017/2018 freezing season
« Reply #804 on: February 08, 2018, 07:28:06 PM »

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #805 on: February 08, 2018, 07:53:01 PM »
What would be the impact of this on the arctic ?

https://watchers.news/2018/02/08/warnings-issued-as-sudden-stratospheric-warming-threatens-europe-with-big-freeze/
If your link connects with Neven's post above, this non-expert guess is while Europe (and Northern Canada ?) freezes the Arctic warms - a lot, (especially on Atlantic half ?). But wait for the guys who really know.
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uniquorn

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Re: The 2017/2018 freezing season
« Reply #806 on: February 08, 2018, 07:58:06 PM »
Worldview 8th Feb Brightness Temperature(Band15, Night)

Nares Strait bottom left.

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #807 on: February 08, 2018, 08:58:50 PM »
What would be the impact of this on the arctic ?

https://watchers.news/2018/02/08/warnings-issued-as-sudden-stratospheric-warming-threatens-europe-with-big-freeze/

That's a very badly written article I'm afraid.

Firstly SSWs in general, are not that rare.

It then says " hasn't occurred since 2010 when it brought coldest March for 51 years to Scotland."

I imagine they are trying to refer to the year 2013. March 2010 saw just average temperatures in Scotland.

Back in early Jan 2013 there was a substantial SSW event followed by the usual media circus throughout Europe of impending severe cold. Jan and Feb passed. The extreme cold weather occurred over far to the SE of Europe over Kazakhstan, the Southern part of Russia and the Northwestern part of China during mid-January 2013. Finally in March 2013  there was a strong blocking Scandanavian High which gave many European countries (including Scotland) cold weather.

It is stretching things to say this blocking high was the downstream result of events back in early Jan 2013.

The one thing I would agree with in the article is where they say the "process won't take place overnight as it usually takes 10 to 25 days to form (down in the troposphere) and there is still uncertainty of how things will develop." 

2 to 4 weeks. Not two months. The UKMO in their analysis of 2013 event mention the SSW was only one of many contributory factors.

Back to 2018. It is pretty much on the cards now for an SSW event. But what will that mean for us landlubbers down in the troposphere (and more relevant to this forum - what will it mean for the Arctic Sea Ice ?

It is too soon to look for guidance from the medium range models and from what I have seen so far the longer range models are a bit all over the place - sometimes showing a Scandanavian High, sometimes just more of the status quo.

So a lot of uncertainty. With SSW events there are few definites as to where the HP will locate, where the blocking will occur - if even at all.

In the medium term the big Fram storm earlier this week has circulated a lot of mild Atlantic air deep into the Arctic and more to come it seems (Bering side looks mild too).

But when looking at a big overall picture like the DMI N80 mean temp (which I expect will keep very high for several days now), the more specific temps for a smaller zones may go unnoticed.

Looking at Jim Hunt's images, the ice is particularly fragile now in the area to the NE of Svalbard over to the Franz Josef land. But at least the medium term forecast for FJL from yr.no this evening is not all doom and gloom. It shows temps recovering there as we start next week with east winds delivering temps 10 C colder than now.  Still probably above normal (whatever that is now?) but likely as good as we could hope for.
« Last Edit: February 08, 2018, 09:18:19 PM by Niall Dollard »

A-Team

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Re: The 2017/2018 freezing season
« Reply #808 on: February 08, 2018, 10:22:53 PM »
Nice spotting, uniquorn.

Looks like the Fram is starting a receding arch collapse like we see so often for the Nares. The dotted periphery is about two-thirds of the way to north pole, about 300 km short. The Kara ice finger now reaches well inside the arc but on the right-hand side obscured by weather.
« Last Edit: February 08, 2018, 11:02:51 PM by A-Team »

Ice Shieldz

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Re: The 2017/2018 freezing season
« Reply #809 on: February 08, 2018, 10:27:37 PM »
GFS 2-Meter mean temp anomalies. 1st is 7 day forecast. 2nd is Feb. mean to date (Feb. 1st through the 8th). The Chukchi and Barents seas continue their anomalous warmth that we've seen relatively persistently through out the freezing season. Doesn't bode well for these regions in terms of how they stand up to melting mechanisms and negative feedbacks associated with the resultant lower extent, sea ice thickness, etc.  Hopefully we see an abatement in the 7-Day trend of heat invading more of the central pack. However with the PV split, the odds of that kind of heat invasion increase.

Neven

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Re: The 2017/2018 freezing season
« Reply #810 on: February 08, 2018, 10:31:20 PM »
Anyone interested in reading more on SSWs, here's an ASIB guest blog post from 2013, written by Randall Gates: Sudden Stratospheric Warming Causes & Effects
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Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #811 on: February 09, 2018, 01:38:17 AM »
Hopefully we see an abatement in the 7-Day trend of heat invading more of the central pack. However with the PV split, the odds of that kind of heat invasion increase.

It often happens that an SSW event leads to a negative AO index. A negative AO would be better for the Arctic Sea Ice in general.

"Heat invasion" is more linked to a positive AO (which is what we have at present). 


FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #812 on: February 09, 2018, 02:49:28 AM »
This polar vortex splitting event in February will not produce several months of subsidence over the pole as the major stratospheric warming of January 2013. This event doesn't completely destroy the vortex, it displaces it to North America. Air is likely to subside over northern Siberia. Northern and central Siberia may have 4 to 6 weeks of colder than normal weather.

Events that take place in February have lesser impacts than events in early January.

Read Judah Cohen's blog.

This event is associated with the strongest west Pacific MJO wave on record. The heating was in the tropical Pacific and Indonesian regions. This is an atmospheric wave driven event. Heating is caused by wave dynamics, not lifting air off of the cold desert in the middle of winter. The physics is brutal. The explanation given in the guest blog post is just plain wrong. The potential temperature of the atmosphere at 200mb high above the deserts of Asia is much warmer than the surface potential temperature. That's why Beijing has such bad smog in the late fall and winter months. Air near the surface cannot rise much because of strong inversions.

Anyway, this is going to be primarily a wave 2 splitting event, not a wave 1 sudden stratospheric warming event so even if you don't follow what I just said, this event has very different dynamics than the 2013 event which was a sudden stratospheric warming driven by wave 1.

I'm a geochemist, not an atmospheric physicist. However, I studied enough geophysics to know that the blog post on SSWs proposed a mechanism that is not compatible with basic physics.

Do not expect this vortex splitting event to be good for sea ice because the cooling effects are likely to affect the continents, not the Arctic ocean.

Below is an image of today's velocity potential anomaly. Green show areas of rising air. Red shows subsidence.

Below is a 3 day forecast of momentum flux driven by planetary wave 2. There's a very large momentum flux at 50º N. Note that wave number 2 is consistent with warm oceans/Arctic and cold continents.

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #813 on: February 09, 2018, 03:02:15 AM »
In March and April the CFSv2 model predicts enhanced subsidence over the far north Pacific. This forecast is consistent with the known effects of La Niña, perhaps enhanced by the event in the stratosphere.

This forecast subsidence pattern would not help sea ice thickening.

jdallen

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Re: The 2017/2018 freezing season
« Reply #814 on: February 09, 2018, 04:51:59 AM »
In March and April the CFSv2 model predicts enhanced subsidence over the far north Pacific. This forecast is consistent with the known effects of La Niña, perhaps enhanced by the event in the stratosphere.

This forecast subsidence pattern would not help sea ice thickening.
I will hasten to add... both 2007 and 2012 were either in or on the slopes of a La Nina.
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numerobis

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Re: The 2017/2018 freezing season
« Reply #815 on: February 09, 2018, 06:50:45 AM »
Chilly across Nunavut for the past few days — some new daily record lows. That’ll thicken up the pressed garlic, along with a bunch of ice that will melt regardless.

jdallen

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Re: The 2017/2018 freezing season
« Reply #816 on: February 09, 2018, 07:30:30 AM »
Chilly across Nunavut for the past few days — some new daily record lows. That’ll thicken up the pressed garlic, along with a bunch of ice that will melt regardless.
It will, and unfortunately at this point a few days - even a few weeks - of record lows won't thicken the ice as much as we need.  Most of that ice is already 2-ish Meters thick, which means there's fairly considerable lag in the heat transfer.  Temps need to go down and stay down at around -30/40C for things to improve.
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FredBear

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Re: The 2017/2018 freezing season
« Reply #817 on: February 09, 2018, 01:07:00 PM »
Hi numerobis, the weather reports at the Kimmirut page seem to have frozen at 19 January (the forecasts & photo still change). I have noticed the forecasts have been much colder than the averages would lead us to expect lately.

El Cid

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Re: The 2017/2018 freezing season
« Reply #818 on: February 09, 2018, 01:21:19 PM »
Anyone interested in reading more on SSWs, here's an ASIB guest blog post from 2013, written by Randall Gates: Sudden Stratospheric Warming Causes & Effects

Thanks! That is just the thing I was asking about in "Stupid Questions"!

numerobis

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Re: The 2017/2018 freezing season
« Reply #819 on: February 09, 2018, 06:42:28 PM »
FredBear: you can get all the Environment Canada reports here:
https://weather.gc.ca/forecast/canada/index_e.html?id=NU

jdallen: Every little bit helps. Lower surface temps mean the ocean will start up with that much less heat content, even if there is a lag, so it'll melt more slowly in the "warm" season.

But that's for the Canadian Arctic. Siberia and Alaska are steaming, relatively speaking. And the cold spell, while persisting here in the East for another week, has been pushed out of Western Nunavut by a nice little storm (which is cancelling flights out of Cambridge Bay).

romett1

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Re: The 2017/2018 freezing season
« Reply #820 on: February 09, 2018, 08:49:24 PM »
The Chukchi and Barents seas continue their anomalous warmth that we've seen relatively persistently through out the freezing season.
Looks like melting season and not freezing - Pacific side Feb 6 - Feb 8. Indeed, current models show warmth until at least Feb 19 over Bering and Chukchi.

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Re: The 2017/2018 freezing season
« Reply #821 on: February 09, 2018, 10:49:42 PM »
The Chukchi and Barents seas continue their anomalous warmth that we've seen relatively persistently through out the freezing season.
Looks like melting season and not freezing - Pacific side Feb 6 - Feb 8. Indeed, current models show warmth until at least Feb 19 over Bering and Chukchi.
Retreat in the Bering does not surprise me, not one little bit.  There's plenty of heat just below the surface, which itself for the most part is near or above 0C.  Add in rising amounts of insolation, and the slash ice that is standing in for "pack" will vanish quite readily.
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Re: The 2017/2018 freezing season
« Reply #822 on: February 10, 2018, 12:37:10 AM »
Wondering how much of the persistence of 2 meter atmospheric heat is tied to the fact that the waters are so much warmer? I'm not talking about how the lack of sea ice relates to larger synoptics that deliver atmospheric heat, but rather how the net effect of warmer water (even under the ice) locally contributes to persistent atmospheric heat anomalies?


jdallen

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Re: The 2017/2018 freezing season
« Reply #823 on: February 10, 2018, 02:58:04 AM »
Wondering how much of the persistence of 2 meter atmospheric heat is tied to the fact that the waters are so much warmer? I'm not talking about how the lack of sea ice relates to larger synoptics that deliver atmospheric heat, but rather how the net effect of warmer water (even under the ice) locally contributes to persistent atmospheric heat anomalies?
My reflex answer was "Yes", but thinking about it, I'm not so sure.

Where you have open water, I think the answer is somewhat yes, as the dynamic exchange with atmosphere will buffer temperatures via the huge reservior of heat available in ocean generally. There the factor is less to do with anything about higher water temperatures and much related to the simple fact there is open water.

Where ice is present, not so much, as ice seriously impedes heat flow.
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DavidR

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Re: The 2017/2018 freezing season
« Reply #824 on: February 10, 2018, 03:23:01 AM »
Wondering how much of the persistence of 2 meter atmospheric heat is tied to the fact that the waters are so much warmer? I'm not talking about how the lack of sea ice relates to larger synoptics that deliver atmospheric heat, but rather how the net effect of warmer water (even under the ice) locally contributes to persistent atmospheric heat anomalies?
My reflex answer was "Yes", but thinking about it, I'm not so sure.

Where you have open water, I think the answer is somewhat yes, as the dynamic exchange with atmosphere will buffer temperatures via the huge reservoir of heat available in ocean generally. There the factor is less to do with anything about higher water temperatures and much related to the simple fact there is open water.

Where ice is present, not so much, as ice seriously impedes heat flow.

However ice doesn't form where there is heat. So part of the reason for a slow build up of ice in the Pacific is the increase in temperatures in the sea there as shown in the graph. I  have emphasized the effect of pacific water temperatures by listing the years according to the increase in sea ice from now to the maximum. 2014 had a large late increase in March reflecting the plunge in temperatures in that  month.

« Last Edit: February 10, 2018, 03:35:17 AM by DavidR »
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jdallen

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Re: The 2017/2018 freezing season
« Reply #825 on: February 10, 2018, 03:50:08 AM »
Speaking of... Over the nest week, GFS has temperatures consistently 5-10C warmer than normal over the Arctic almost in its entirety.

Heat over the Bering is particularly sharp, and the ice there is already in serious trouble.  Snapshot (somewhat fuzzy, but resolveable) from Worldview today below.
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aperson

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Re: The 2017/2018 freezing season
« Reply #826 on: February 10, 2018, 05:29:43 AM »
That prompted me to check the other side of the Bering Strait. Holy fuck.

Top: Feb 4th bands 7-2-1
Bottom: Feb 9th bands 7-2-1
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #827 on: February 10, 2018, 09:27:57 AM »
Wondering how much of the persistence of 2 meter atmospheric heat is tied to the fact that the waters are so much warmer? I'm not talking about how the lack of sea ice relates to larger synoptics that deliver atmospheric heat, but rather how the net effect of warmer water (even under the ice) locally contributes to persistent atmospheric heat anomalies?
My reflex answer was "Yes", but thinking about it, I'm not so sure.

Where you have open water, I think the answer is somewhat yes, as the dynamic exchange with atmosphere will buffer temperatures via the huge reservior of heat available in ocean generally. There the factor is less to do with anything about higher water temperatures and much related to the simple fact there is open water.

Where ice is present, not so much, as ice seriously impedes heat flow.

ice seriously impedes heat flow.

I am sure you are right, but my question is what impedes the heat flow, as the thermal conductivity of ice (and any snow on top) is greater than that of water. Is it because of wind and waves and turbulence assisting the process?
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gerontocrat

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Re: The 2017/2018 freezing season
« Reply #828 on: February 10, 2018, 10:35:54 AM »
Sudden Stratospheric Warming - something going on this weekend

https://www.netweather.tv/weather-forecasts/news/8730-sudden-stratospheric-warming-this-weekend-but-what-is-it-how-will-it-affect-our-weather

I like this article from Netweather as it is full up caveats and uncertainties, and brings in the MJO,  Atmospheric Angular Momentum (AAM)  and La Nina, and the  Quasi-Biennal Oscillation (QBO), all of which seem to increase the possibility of high latitude blocking and a risk of nationwide (UK) sustained colder weather later this month.

Effect on the Arctic ? Another wait and see job.
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Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #829 on: February 10, 2018, 10:41:16 AM »
An interesting insight into CryoSat-2 sea ice thickness measurements from Stefan Hendricks on Twitter:

http://GreatWhiteCon.info/2018/02/the-february-2018-fram-strait-cyclones/#Feb-09
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A-Team

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Re: The 2017/2018 freezing season
« Reply #830 on: February 10, 2018, 01:21:42 PM »
Quote
Thomas Lavergne's 48-hour sea ice drift products are hosted at OSI SAF https://tinyurl.com/y8bsc24m
The montage below shows 156 days of those from early Sept up to Feb 9th. The storms show up very clearly as dark blotches (from the longer black velocity vectors being consolidated by the 14x downscaling). The mp4 goes through these days one at a time. Less than 3% are traditional 'Beaufort Gyre' or 'TransPolar Drift' days, though depictions of those concepts have gone strongly adrift from their traditional moorings. There is zero support for either in the velocity-vector grid averaged over the last six months.

These two-day vectors do not provide net drift (floe trajectories) over the freezing season; that can only be done by feature tracking. The OSI SAF netCDFs are broken at the moment but the drift vectors lift off fairly well off the graphics onto Ascat overlays, for which I've made some 700 days of separate land and daily open water masks from AMSR2.

These suppress weather noise on Ascat allowing ice features to be tracked through the summer melt season. A couple of the in-house LUTs at ImageJ are actually more effective for feature tracking than the original imagery. The lighter blue on OSI SAF denotes 'open ice' and so provides a convenient mask refinement, amounting to an unspecified cut-off on AMSR2 sea ice concentration.
« Last Edit: February 10, 2018, 01:49:02 PM by A-Team »

A-Team

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Re: The 2017/2018 freezing season
« Reply #831 on: February 10, 2018, 04:10:28 PM »
The first time series below reviews the six day storm. Some bland weather is ahead in terms of winds capable of setting the ice notably in motion, though Fram export will continue (bottom 4-day). Warm air and less ice thickening is a separate forecast consideration.

Part 2 of this epic study of ice-busting waves on the Beaufort just came out:

Wave attenuation through an Arctic Marginal Ice Zone
F Ardhuin ... P Wadhams  https://tinyurl.com/y8fanoat free full

The second movie reviews ice motion in the Chukchi-ESAS-Bering Strait region for the last 100 days from four perspectives: OSI SAF, Ascat 2x-enhanced, UB SMOS ice thinness, and Ascat 2xe-indexed. The ice here is milling about, with little trend to displacement. It will melt out in situ next summer if this pattern continues. The quadrant shown has the north pole in lower right corner.

There would be no persistent ice in the Arctic Ocean were it not for confinement by its basin. Here the De Long islands, notably Zhakhova, Bennett and Henrietta (Ostrov Genriyetty) in the New Siberian Islands (Novosibirskiye Ostrova) may pose somewhat of a barrier to further westward motion. (Henrietta, together with Ellesmere and Komsomolets in SZ, are the limits to ice pack rotation.)  Bennett has permanent ice and is always visible in Ascat; it often shows lee atmospheric plumes (see https://en.wikipedia.org/wiki/Bennett_Island for discussion) and less commonly ice wakes like Ushakov but see about day 320 below.

Quote
Technical note: The mp4 in the upper right initially struggled to capture gray scale nuances with all the competition from color in the other quarters, eventually pixelating even though the original was saved out under the 'excellent' option. The .mov format uploads and downloads but does not display. I currently save out as .avi using 'raw' and 'excellent', open that huge file in Quicktime, which it converts to its .mov, which it then converted to .mp4 at the most excellent converter https://www.online-convert.com/
« Last Edit: February 10, 2018, 10:48:40 PM by A-Team »

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #832 on: February 10, 2018, 04:21:35 PM »
The GFS, CFS and ECMWF models all show much warmer air over the Arctic ocean and colder than normal temperatures in Siberia. Intense storm activity in the subpolar seas of the Atlantic is pulling the cold air on the north American side towards the Labrador, Irminger and Greenland seas. The far north Pacific ocean will also have storms impacting the Berning strait. The northern hemisphere has a wave 2 pattern from sea level to the top of the stratosphere with a warm Arctic, warm oceans and cold continents. Coastal western Europe will be colder than normal because of multiple periods of northerly and easterly flow.

This will not be like the 2013 SSW. A weakened polar vortex will remain on the North American side and high pressure will be strongest over northern Siberia. Heat will be advected over the Arctic ocean from both the Atlantic and Pacific oceans.

This pattern may be setting up for this year to have the lowest Arctic sea ice maximum on record. It's very much a continuation of the WACC pattern we have seen all fall and winter.

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Re: The 2017/2018 freezing season
« Reply #833 on: February 10, 2018, 04:34:43 PM »
It's very much a continuation of the WACC pattern we have seen all fall and winter.
Now I know what WACC is,  "WACC stands for Warm Arctic Cold Continents" (so Neven said back in 2012 on his blog).

It does not stand for "Weighted average cost of capital (WACC) is a calculation of a firm's cost of capital in which each category of capital is proportionately weighted" which is the first and almost only response by Google (shows Google's priorities?)
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SteveMDFP

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Re: The 2017/2018 freezing season
« Reply #834 on: February 10, 2018, 04:52:30 PM »


ice seriously impedes heat flow.

I am sure you are right, but my question is what impedes the heat flow, as the thermal conductivity of ice (and any snow on top) is greater than that of water. Is it because of wind and waves and turbulence assisting the process?

Yep.  The thermal conductivity of water is a measure that assumes zero bulk flow by any mechanism.  Wind, waves, turbulence and especially temperature differentials drive huge amounts of bulk flow.  If water cools at the surface, it becomes denser and sinks, replaced by slightly warmer water.  The importance of thermal conductivity of water is tiny in comparison to the thermodynamic effects of bulk flow.

Air is a great insulator.  But step outside in a freezing gale, and all that insulating capacity doesn't exactly keep you warm.


FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #835 on: February 10, 2018, 05:39:28 PM »
Notice how the Arctic ocean salinity at 30m depth has changed according to the Mercator ocean model. There has been a surge of moderately salty Pacific water through the Bering Strait. The fresh water lens of the Beaufort high has been pushed towards the Canadian side of the northern coast of Alaska. The west side of the main channel of the CAA has freshened as has the west side of the Labrador sea.

The salinity changes show increasing outflow through the CAA and increasing inflow of Pacific water at 30m (100 feet). Of course, if we go down to 300m depth we see something very different because the Fram straight is very deep while the Bering strait has a shallow sill, but these data support A-Team's assertion that the supposed transpolar drift is not working now.
« Last Edit: February 10, 2018, 05:50:13 PM by FishOutofWater »

oren

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Re: The 2017/2018 freezing season
« Reply #836 on: February 10, 2018, 06:19:01 PM »
The montage below shows 156 days of those from early Sept up to Feb 9th. The storms show up very clearly as dark blotches (from the longer black velocity vectors being consolidated by the 14x downscaling). The mp4 goes through these days one at a time. Less than 3% are traditional 'Beaufort Gyre' or 'TransPolar Drift' days, though depictions of those concepts have gone strongly adrift from their traditional moorings. There is zero support for either in the velocity-vector grid averaged over the last six months.

These two-day vectors do not provide net drift (floe trajectories) over the freezing season; that can only be done by feature tracking. The OSI SAF netCDFs are broken at the moment but the drift vectors lift off fairly well off the graphics onto Ascat overlays, for which I've made some 700 days of separate land and daily open water masks from AMSR2.
Thank you A-Team, the ice-drift animation is highly instructive, allowing to visually understand the contribution of drift vs. in situ freezing (and occasional melting) to wintertime ice growth and retreat.
The second movie reviews ice motion in the Chukchi-ESAS-Bering Strait region for the last 100 days from four perspectives: OSI SAF, Ascat 2x-enhanced, UB SMOS ice thinness, and Ascat 2xe-indexed. The ice here is milling about, with little trend to displacement. It will melt out in situ next summer if this pattern continues. The quadrant shown has the north pole in lower right corner.
It is striking how the ice struggles to thicken in the Bering Strait area, due to inflow of Pacific water and warm air. For what seems like the last 30 days of the animation the SMOS thin ice area remains mostly the same and refuses to disappear.

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Re: The 2017/2018 freezing season
« Reply #837 on: February 10, 2018, 06:50:10 PM »
I bet these wily Canadians know all about sill height barriers between the Arctic Ocean and the CAA ... don't have time to chase that down today but see:

http://onlinelibrary.wiley.com/doi/10.1002/jgrc.20330/full 

Quote
The Canadian Arctic Archipelago throughflow in a multiresolution global model: Model assessment and the driving mechanism of interannual variability
C Wekerle et al 13 Sept 2013

The volume and freshwater transports through the Canadian Arctic Archipelago (CAA) are assessed using the unstructured-mesh Finite Element Sea ice-Ocean Model (FESOM) in a global setup with the CAA resolved at 5 km scale. The hindcast simulation realistically represents fluxes through the main gates of the Arctic Ocean and the Arctic sea ice conditions.

During the period 1968–2007, the mean volume transports through Lancaster Sound and Nares Strait amount to 0.86 and 0.91 Sv, respectively. The monthly mean volume transport through western Lancaster Sound is highly correlated with the observational estimate (r = 0.81). The seasonal variability of the Lancaster Sound transport is well represented in the model. The simulated mean CAA freshwater export rate is 123 mSv, slightly higher than the observational estimate. The interannual variability of CAA volume transports is determined by sea surface height (SSH) gradients between the Arctic Ocean and northern Baffin Bay.

The sea level upstream of Lancaster Sound is mainly determined by that along the Beaufort Sea coast, which can be explained by changes in the wind regimes (cyclonic versus anticyclonic) associated with release or accumulation of freshwater in the Beaufort Gyre. Sea level variations downstream of Lancaster Sound and Nares Strait are connected to SSH variations in the eastern Baffin Bay and in the Labrador Sea, which can be attributed to the variability of ocean-atmosphere heat fluxes. Both processes upstream and downstream of the CAA are linked with the North Atlantic Oscillation type of atmospheric variability.

The local mesh refinement of ∼5 km allows us to investigate the contribution of individual narrow straits to the Parry Channel volume transport. The volume transports through these straits show a very similar variability.

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Re: The 2017/2018 freezing season
« Reply #838 on: February 10, 2018, 07:05:52 PM »
<snippage>
ice seriously impedes heat flow.

I am sure you are right, but my question is what impedes the heat flow, as the thermal conductivity of ice (and any snow on top) is greater than that of water. Is it because of wind and waves and turbulence assisting the process?
Water is dynamic and while the "r" value of water may be less than ice, water can transfer heat via convection, which ice cannot.

Water will also loose heat via evaporation, which ice will not, so you have a loss from phase change in addition to straight-up thermal transfer.
« Last Edit: February 10, 2018, 07:24:06 PM by jdallen »
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Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #839 on: February 10, 2018, 10:45:22 PM »
It's very much a continuation of the WACC pattern we have seen all fall and winter.
Now I know what WACC is,  "WACC stands for Warm Arctic Cold Continents" (so Neven said back in 2012 on his blog).

It does not stand for "Weighted average cost of capital (WACC) is a calculation of a firm's cost of capital in which each category of capital is proportionately weighted" which is the first and almost only response by Google (shows Google's priorities?)

I might be narcissistic, but I much prefer the cold continent be Asia, not North America.  I know that in the long (?) run cold is only relative, but I don't really have a long run ahead of me.

Dharma Rupa

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Re: The 2017/2018 freezing season
« Reply #840 on: February 10, 2018, 11:03:58 PM »
Since the end of December 2015 the DMI 80N has fallen below 245K exactly once, and it has never fallen to the historical average in Winter at all.  It is getting to be a bit too long to call that weather, and I think it might be the definition of this "freezing" season.

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Re: The 2017/2018 freezing season
« Reply #841 on: February 10, 2018, 11:41:32 PM »
Since the end of December 2015 the DMI 80N has fallen below 245K exactly once, and it has never fallen to the historical average in Winter at all.  It is getting to be a bit too long to call that weather, and I think it might be the definition of this "freezing" season.
From about end October to sometime in March DMI 80 N goes up and down like a yo-yo every year, and then varations become less. 2016-17 winter was probably warmer than 2017-18. Since about 2015 winter temps have rarely been below the average.
However, surely the low extent this year is more to do with temps at lower latitudes than 80+ and ocean heat getting into the Arctic?

But what do I know
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numerobis

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Re: The 2017/2018 freezing season
« Reply #842 on: February 11, 2018, 06:21:04 AM »
<snippage>
ice seriously impedes heat flow.

I am sure you are right, but my question is what impedes the heat flow, as the thermal conductivity of ice (and any snow on top) is greater than that of water. Is it because of wind and waves and turbulence assisting the process?
Water is dynamic and while the "r" value of water may be less than ice, water can transfer heat via convection, which ice cannot.

Water will also loose heat via evaporation, which ice will not, so you have a loss from phase change in addition to straight-up thermal transfer.

Not to mention that liquid water is at least -2 C, whereas ice can be cold. Ice presents the atmosphere with a surface about the same temperature as the air (-40 for example), and has linear increase in temperature as you go down. Water shows the air -2C.

Ice though isn’t actually an unbroken slab. There’s holes all over the place where heat (and mammals) can poke through the ice. In open water I assume the effect on temperature flux is slight, but near shore we see in Iqaluit the steam come out through tidal cracks. I’d expect the narrow passages through the archipelago would also provide a fair bit of creasing and cracking.

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Re: The 2017/2018 freezing season
« Reply #843 on: February 11, 2018, 09:52:20 AM »


I might be narcissistic, but I much prefer the cold continent be Asia, not North America.  I know that in the long (?) run cold is only relative, but I don't really have a long run ahead of me.
[/quote]

Well, for some reason, I think that let North America be the cold one, and keep Europe nice and cozy during winter :D

Hyperion

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Re: The 2017/2018 freezing season
« Reply #844 on: February 11, 2018, 02:34:22 PM »
<snippage>
ice seriously impedes heat flow.

I am sure you are right, but my question is what impedes the heat flow, as the thermal conductivity of ice (and any snow on top) is greater than that of water. Is it because of wind and waves and turbulence assisting the process?
Water is dynamic and while the "r" value of water may be less than ice, water can transfer heat via convection, which ice cannot.

Water will also loose heat via evaporation, which ice will not, so you have a loss from phase change in addition to straight-up thermal transfer.

Not to mention that liquid water is at least -2 C, whereas ice can be cold. Ice presents the atmosphere with a surface about the same temperature as the air (-40 for example), and has linear increase in temperature as you go down. Water shows the air -2C.

Ice though isn’t actually an unbroken slab. There’s holes all over the place where heat (and mammals) can poke through the ice. In open water I assume the effect on temperature flux is slight, but near shore we see in Iqaluit the steam come out through tidal cracks. I’d expect the narrow passages through the archipelago would also provide a fair bit of creasing and cracking.
I think this is very important point. Especially when you have a situation like north of Svalbard last week with large long swell penetrating deeply into fragile pack with deep heterogeneous layered water with much heat below.
Its worth downloading the data http://imb-crrel-dartmouth.org/imb.crrel/irid_data/2017B_clean.csv from imb 2017B which finally took the fram exit ramp along with co-locate itp95 late December. The charts show the picture in brief:






, but looking closely at the in depth thermistor data is far richer.
spreadsheet column format:
1Date   2Latitude (degrees)   3Longitude (degrees)   4Quality (+/- km)   5Air Temp (C)   6Air Pressure (mb)   7Snow Surface Position (m)   8Ice Thickness (m)   9Ice Surface Position (m)   10Ice Bottom Position(m)   11T1 (C)   12T2 (C)   13T3 (C)   (....further thermistors at 10cm intervals)

and final data point on 12/12/2017:
12/12/2017 12:00   83.30389   2.17579   GPS   -6.09   1003.13   0.39   0.74   0   -0.74   -6.42   -5.6   -4.85   -4.1   -3.72   -3.34   -2.84   -2.4   -1.96   -1.77   -1.83   -1.83   -1.83

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 and up to mid December when they stopped reporting no bottom growth or thickening was achieved. However the snow load had built to 40cm from sea level to above. It is possible that more than 40cm of snow actually built up, the portion of this weighted to below waterline, or wicking up water, scavenging a little inter-grain ice crystal growth from the seawater. And a little bottom melt continued at least up to end of data. whatever, the ice never got above 0.75m thick.

Anyway IMO any of this ice or snow would be ridiculous to portray as anything but fragile, porous, soggy with seawater and brine inclusions.

You get big long swell propagating hundreds of km into stuff like this like last week, then unlikely its anything but a soggy slushy, wetted with seawater to the snow surface by swells 4-6 times a minute . It wouldn't surprise me if heat transfer seawater to atmosphere can far exceed open water in situations like this. The surface area of water exposed to the air would be far greater, and phase change when air temps are below zero probably allows latent heat to  transfer to atmosphere too.

its an ongoing source of extreme frustration that imb's 2017C,D are still being data censored in the Beaufort, where the have been colocates with itp's 101 and 108 for six months.











IMHO a coordinated pester campaign to the following email addresses would be appropriate:

"To obtain information on the datafiles contact Don Perovich at Donald.K.Perovich@Dartmouth.edu"

"Please address any questions regarding the data to Bruce Elder ( Bruce.C.Elder@usace.army.mil )"

These have always previously been available from prior missions. Be nice to have an explanation at least, better still the valuable picture of whats going on that tax dollars have paid for.

« Last Edit: February 11, 2018, 09:48:13 PM by Hyperion »
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uniquorn

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Re: The 2017/2018 freezing season
« Reply #845 on: February 11, 2018, 03:26:34 PM »
The northern hemisphere has a wave 2 pattern from sea level to the top of the stratosphere

Nullschool 10hPa (~30,000m) 2018-02-11

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Re: The 2017/2018 freezing season
« Reply #846 on: February 11, 2018, 05:02:45 PM »
Quote
the ice struggles to thicken in the Bering Strait area ... the last 30 days thin ice area remains mostly the same and refuses to disappear.
Right, Oren. The ice here is not paying the slightest attention to peer-reviewed climate models. The mp4 below shows 516 consecutive days of UH AMSR2 sea ice concentration for the Chukchi-Bering Strait region, from 10 Sep 2016 to 10 Feb 2018. During this period, for the region shown shown, open water made up 26.1% of the scene (excluding land) on average, intermediate concentration ice 37.1%, and solid ice 36.8%. Thus on average 63.2% of the time this area was not frozen solid over the course of the last seventeen months.

The second montage version makes better use of space; the faint blues of intermediate concentration ice have been enhanced. There's a prolonged run-up to the main open water season as well as a prolonged aftermath. Those are the near-future directions.

Technical note: it looks like we could run 3 full years of this 555 x 233 pixel frame and still stay under 10MB forum file size. The 233 is set up to allow for 555 x (3x233) or 555 x 699 so under 700 pxl height. Thus the three years could be run simultaneously.

However the plan here is to use those two slots for Ascat and Smos with an OSI SAF ice motion vector overlay. The mega-automation floe server of Dryland over at DevCorner really comes into play when combining 4 separate netCDF assemblages over a freeze season or multiple years, especially updating daily to the current date which is approaching inconceivable on a human scale.

The former is flashy during the summer and needs the AMSR2 for its land and daily water mask; Smos takes a break during the summer. It might make more sense just to start on Oct 1st and compare freezing seasons, with 2018 pausing at whatever the current date.

It takes 700 x 190 pixels to show a year of montage. That pencils out to 3.7 years per 700 x 700 or 14.7 years that could be shown with the four-image forum limit. The UH archive begins 01 Aug 2012 so it could all be shown, with some trimming at ~2x the resolution shown below. It contains various glitches in satellite function as well as inexplicable image size changes.

The dates are hidden by the forum controller so mouse it away to see them. I could put them sideways but otherwise it gets away from automation options.
« Last Edit: February 11, 2018, 10:40:47 PM by A-Team »

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #847 on: February 11, 2018, 06:29:29 PM »
That little movie of the Bering strait is devastating, A-Team.  The strait has a shallow sill, so it used to be that there was only a "summer water" effect and there was no effective heat transport through the strait. The Pacific water was completely stripped of its heat. The strait is effectively completely open now, in mid-February, with a thin veneer of broken ice and slush on top. Not only is salt moving into the Arctic, heat is entering under the thin ice. There's not much heat, but it's there.

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Re: The 2017/2018 freezing season
« Reply #848 on: February 11, 2018, 07:27:20 PM »
To my eyes it seems the catastrophic salinity situation along the Pacific front is to be blamed on the lack of coastal ice formation along Russia's Bering shoreline. Residual summertime heat and constant buffering by winds has left this stretch of normally frozen water open.

Simultaneously, the Alaskan shoreline has actually frozen up relatively more substantially this winter.

It seems when this situation occurs, the large concentration of sea ice to the south of waters that are normally not open acts as an enormous suctioning mechanism, transporting large amounts of salty Pacific water directly into the Arctic.

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #849 on: February 12, 2018, 01:39:34 AM »
Southerly wind anomalies in the Bering strait and far eastern Siberia regions have increased the flow of Pacific water into the Arctic seas.