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subgeometer

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Re: The 2017/2018 freezing season
« Reply #750 on: February 03, 2018, 01:33:27 AM »
Wow, computer breaks for a week and when it comes back up - that's some storm forecast

The ECMWF forecast currently has tit bottoming out at 947mb

romett1

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Re: The 2017/2018 freezing season
« Reply #751 on: February 03, 2018, 11:38:08 AM »
The models this evening are indicating that the main storm centre will track up the Fram Strait late Sunday/Monday and then grind to a halt somewhere between the Pole and Severnaya Zemlya on Tuesday and slowly fill.
After this storm new one is already coming sometime between Thursday and Saturday. Of course it's bit too far, but worth to keep an eye on.

A-Team

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Re: The 2017/2018 freezing season
« Reply #752 on: February 03, 2018, 03:43:16 PM »
Some things to watch here are total precipitable water (advection of warm moisture, snow blanket), effect of waves incident to the Barents ice edge (monitorable by UH SMOS thinness and Sentinel-1AB), and induced translation, rotation, divergence, compression and export of the overall icepack (monitorable by Ascat).

This storm could leave an imprint on the upcoming melt season, notably by upending Atlantic Waters along the Barents Edge.

Mercator Ocean has a nine-day forecast of this region at four relevant depths out to 10 Feb 18, the ever-changing color scale masking any drama and precluding pre- and post-storm differencing. They have fixed some earlier programming blunders but still have not corrected overly dynamic palette squashing nor do they release netCDF files so someone else could. 

People frequently post outdated journal factoids to the effect AW is at 300 m depth and so doesn't come in contact with surface ice; actually incoming warmth has long been evident at intermediate depths of 100 m and 30 m as well as the surface. There is abundant buoy and CTD cast data for this region in addition to MercOcean depictions.

http://bulletin.mercator-ocean.fr/en/PSY4#4/47.22/-62.71

GFS is showing 948 hPa attained on Monday with a peak wind of 104 km/hr. For a reality check, there are actual weather stations at Alert CA, Kap Morris Jesup and Nord in northern Greenland, Ny Alesund in Svalbard and FJL, Ostrov Ushakov and SZ in Russia.

https://www.timeanddate.com/weather/canada/alert Alert
https://www.timeanddate.com/weather/@3421844 KMJ
https://www.timeanddate.com/weather/greenland/station-nord/ext Nord
https://www.timeanddate.com/weather/norway/ny-alesund SV
https://www.timeanddate.com/weather/@562426 FJL
https://www.timeanddate.com/weather/@1488349 OU
https://www.timeanddate.com/weather/@1492613 SZ

Technical note: the TPW graphic is not ideal for our purposes, being on a mercator projection sliced meridionally out of Arctic geo-registration, showing only two days out and using a very poor contrast color palette at high latitudes. The version here butts up two copies, crops to emphasize the Bering Strait and Barents regions, inverts the color scheme, tweaks the murky red/magentas to show fainter moisture levels better, and deletes its 14 duplicated pause-frames. This is an extensible product over the full extent of the storm.

For time series overlays of Ascat with any netCDF Geo2D product, note it uses 1154 pixels for a 45º horizon centered on the north pole in Greenland down (-45º) stereographic projection. A similarly oriented Panoply map of size 190 with horizon 25º has diameter 684 pixels. These thus use 25.64 and 15.24 pxl/deg respectively, allowing precision rescaling and auto-registration to the pole. Blueing open water and deleting thicker ice and land mask to transparency creates the overlay onto the Ascat (which has technical problems on marginal ice and open water).

To co-register Nullschool with other map products, adjust the url to orient and size the display. Duplicate a whole-window screen capture, excise the numeric display and time, shrink, and overlay on the main weather display. Setting the size at '2000' allows consistent resizing to fit over standard Ascat or netCDF Panoply maps. Toggling 'overlay' to 'none' gives a wind grayscale for simplified overlays.
« Last Edit: February 04, 2018, 02:40:43 PM by A-Team »

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #753 on: February 03, 2018, 06:54:21 PM »
The stratospheric polar vortex has been displaced towards Greenland. That is enhancing the 500mb vortex around Greenland which is going to bring a series of intense storms in the Labrador, Irminger and Greenland seas and into the central Arctic ocean.

The intense storms are blowing very cold Arctic air over the Labrador and Irminger seas at very high speeds. Note that 100 knots, not 100 km/h is the minimum speed of a category 3 hurricane. The repeated blasts of cold air will trigger deep water formation near the shelf slope and a major overturning event in the subpolar seas of the north Atlantic. This will lead to an enormous amount of heat released to the atmosphere and the rapid warming of the Arctic air blown over the subpolar seas.

So much heat will be released that the wave energy will propagate into the upper stratosphere, splitting the stratospheric polar vortex. This splitting will lead to subsidence and high pressure over northern Siberia and easterly flow into Europe from Siberia. Expect western Europe and northern Siberia to be colder than normal for the next  four to six weeks. Expect the Arctic ocean area to have much above normal temperatures for the next 4 to 6 weeks.

Sea ice on the Atlantic side will take a beating from warmth, waves and high dewpoint air. These winds will also import warm water at depth into the Atlantic side of the Arctic ocean while cold Arctic water is exported from the Arctic through the Labrador sea and down to the bottom of the north Atlantic.

This is a major planetary event that will couple the processes from the bottom of the North Atlantic to the top of the stratosphere. Watch it carefully as it evolves. I expect it will be the topic of a number of scientific papers in the years to come. Note that both the ECMWF and GFS models predict this vortex splitting event and have been predicting it for days.
« Last Edit: February 03, 2018, 10:25:38 PM by FishOutofWater »

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #754 on: February 03, 2018, 08:31:41 PM »
The state of play in the Arctic as the latest Fram Strait cyclone is brewing:

http://GreatWhiteCon.info/2018/02/facts-about-the-arctic-in-february-2018/

Including an animation revealing the effects of the previous set:



It has been noted that the latest PIOMAS thickness map from Wipneus shows sea ice where the satellites reckon there is none.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

A-Team

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Re: The 2017/2018 freezing season
« Reply #755 on: February 03, 2018, 08:55:03 PM »
Great to see people coming out of hibernation for this event!

Here are the 'before' Sentinel radar image of the ice for 02 Feb 18 (needs click for full scale) and the side-by-side water temperatures by depth for the same date.

Sea water at these depths and salinities freezes at about -1.81ºC. Surface temperatures are not remotely close now; mixing open water to intermediate depth would make things worse along a 1000 km corridor. Winds don't mix water under ice but year-round currents would move mixed Atlantic Waters east along the Barents Edge continental shelf bathymetry, propagating open water (or early melt).

Finally, just a variation on what JimH already did above. The 'large' version of UH AMSR2 sea ice concentration does quite a bit better around all these little islands. Given the winds more or less orthogonal to the ice edge, it's also worth tracking the less-than-100% ice because it is a prime candidate for consolidation, with low freeboard floes swamped with sea water and fractured by swells possibly a couple hundred km (!) into the ice pack.

The last frame averages out AMSR2 weather flashes over the 33 days and differentiates less solid areas from those consistently all ice. It's repeated as a standalone prediction of the post-storm compaction zone. There'll also be ice piling up on the southern shores of FJL and extended ice eddies on the lee side of Ostrov Ushakov.

Technical note: the UH ftp site is fast, soit takes but a minute to round up the files, change names, drag'n'drop into ImageJ, rotate 90º, crop to the Barents Edge, montage in date text, change colors in gimp off the palette with the color picker, pause on 02 Feb 18 and less-than-solid average, save out as small gif, upload, and get back to gardening before it gets any hotter.
« Last Edit: February 03, 2018, 10:09:10 PM by A-Team »

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #756 on: February 04, 2018, 03:40:36 AM »
2018 Arctic extent still lowest on record for most of January.
Looks like it 'might' claw its way back into the crowd if it keeps trying:

http://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/

nicibiene

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Re: The 2017/2018 freezing season
« Reply #757 on: February 04, 2018, 09:29:21 AM »
Great to see people coming out of hibernation for this event!

No hibernation here.  ;D Highly apprechiate to read the discussion and your amazing graphics here A-Team. I'm following the weather models, trying to learn and to think about (guess) what will happen next. Helpful to read all your information and opinions here. Thanx guys!  :-*

It could be a nice entertaining thriller, if it wouldn't be so scary realistic.... :'(
“We cannot solve our problems with the same thinking we used when we created them.” –“Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning.” Albert Einstein

Paddy

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Re: The 2017/2018 freezing season
« Reply #758 on: February 04, 2018, 09:36:35 AM »
The one consolation in all this is that at least albedo still doesn't matter that much until after the equinox. However, thete's really not much time left for a refreeze if this drives unseasonsl melt.

meddoc

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Re: The 2017/2018 freezing season
« Reply #759 on: February 04, 2018, 10:49:30 AM »
I've never seen such a Storm that close to the Pole in Winter, since nullschool.net is available for public Use.

Probably no Coincidence, that the Land of the Free just declared in their renewed Nuclear Doctrine, that basically they can attack Anyone, Anywhere without any Reason whatsoever, if necessary.

These are the Times, we' re livin in.

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #760 on: February 04, 2018, 11:14:43 AM »
The latest Fram Strait swell forecast for tomorrow afternoon:

http://GreatWhiteCon.info/2018/02/the-february-2018-fram-strait-cyclones/

Note that this is just the underlying long distance swell. There are giant wind waves superimposed on top of that. See the last image. Note also that "significant height" does not refer to the biggest waves:

"Statistically, it is possible to encounter a wave that is much higher than the significant wave.

Given that Hs is 10 metres (33 feet), statistically:

1 in 10 will be larger than 10.7 metres (35 ft)
1 in 100 will be larger than 15.1 metres (50 ft)
1 in 1000 will be larger than 18.6 metres (61 ft)"
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

A-Team

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Re: The 2017/2018 freezing season
« Reply #761 on: February 04, 2018, 03:17:24 PM »
The first image below shows ice along the North Atlantic front on 03 Feb 2018 prior to the storm. A major retreat of ice position can be expected over the next few days.

The mp4 provides some context: 142 days since the 15 Sep 2017 minimum ending on the Feb 3rd. Ascat is fairly noisy when the scene has weather over a mix of open water and ice but the back and forths of the front can still be followed. Ice in the upper Fram will be churned, melted into open water. Scribbler has a good discussion of the extreme advected warmth:

https://robertscribbler.com/category/climate-change-2/

The mp4 for the overall Arctic Ocean shows Fram export really kicking in about day 300. This represents 39% of a full year (minimum to minimum rather than calendar); ice features in the peri-polar region have been stable with no decisive trend in direction (ie the 'TransPolar Drift' is a non-starter).

The transit of the cyclone has slowed since yesterday (per GFS nullschool) and extremes of low pressure and wind have slightly abated. However the winds have been strong and consistent in direction. The central ice pack will be pushed down onto the immovable CAA deforming features and forcing more to the sides, and so accelerating both Beaufort and Fram export of older thicker ice (along with Kara/Laptev intrusion ice).
« Last Edit: February 04, 2018, 05:06:12 PM by A-Team »

charles_oil

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Re: The 2017/2018 freezing season
« Reply #762 on: February 04, 2018, 06:01:46 PM »

Climate re-analyser looks like impressive temperature anomaly too !


http://cci-reanalyzer.org/wx/fcst/#gfs.arc-lea.t2anom

A-Team

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Re: The 2017/2018 freezing season
« Reply #763 on: February 04, 2018, 08:14:12 PM »
Quote
Climate re-analyser: impressive temperature anomaly
Whoa, that is an anomalous anomaly. (I had trouble reading the scale so color-picked the extremes, pooled, and re-colored them as yellow.) The Ny-Ålesund weather station is a little off to the south but it has excellent records (and a daily sonde).

If persistent enough to warm the ice, we may see a tussle between fracturing and flow. Brittle to ductile transitions in ice are discussed in this 1999 classic:

http://www.tms.org/pubs/journals/JOM/9902/Schulson-9902.html
« Last Edit: February 04, 2018, 08:24:42 PM by A-Team »

dnem

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Re: The 2017/2018 freezing season
« Reply #764 on: February 04, 2018, 08:32:30 PM »
Quote
Climate re-analyser: impressive temperature anomaly
Whoa, that is an anomalous anomaly.

That station is around -1 right now or an anomaly of around +13C.  That would make it more or less in accord with the re-anayzer (in the brown colors on the anomaly scale), and both cooler than, and south of, your yellow color-replaced region.  If I'm looking at it right.

Neven

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Re: The 2017/2018 freezing season
« Reply #765 on: February 04, 2018, 11:38:39 PM »
Thanks for all the info, everyone. I'm also watching somewhat more intently than I usually do around this time of year. I'll try and incorporate some of the stuff in the next PIOMAS update, or perhaps do a separate blog post (if time and circumstance permit).

Here's my modest contribution, the Climate Reanalyzer precipitation forecast for the coming 10 days:

Compare, compare, compare

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #766 on: February 05, 2018, 03:08:34 AM »
Thanks again A-Team...
Quote
... ; ice features in the peri-polar region have been stable with no decisive trend in direction (ie the 'TransPolar Drift' is a non-starter ...

We clearly need some new thoughts on how the Arctic Sea Ice drifts. I've been assuming Transpolar Drift would be more of a constant feature also when there's no ice essentially forming almost an unidirectional flow through Bering straits bringing warmer Pacific water to Arctic Atlantic. The height of sea level is almost always higher at Bering than Atlantic ice edge so I've thought it could stack on the ESS shallows flowing transpolarly straight to Fram.

This might not be the case in the future.  In any case, we do not (yet) have a fully liquid ocean at a rotational pole of a planet to look at as an exsample, so some theorizing might, could, should be done. Of course we'll see how it settles once it's ice free, but the Greenland messes with the incoming currents for the time being.
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Ice Shieldz

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Re: The 2017/2018 freezing season
« Reply #767 on: February 05, 2018, 04:26:51 AM »
Forecasts pointing toward several more days with an active north Atlantic cyclone cannon, albeit perhaps not with cyclones as strong and/or invasive as the current one. My understanding is that the onset of this northward heat transfer caused models to forecast our upcoming SSW – which will split the polar vortex and couple tightly with the troposphere. This opens the door for more cyclones and associated WACCy weather. Below is a 65N 10hpa zonal wind forecast and an animated ECMWF 10-day forecast for 10hpa winds.

FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #768 on: February 05, 2018, 05:09:58 AM »
There's very strong wave 2 driving causing this polar vortex split. Nice animation of the ECMWF forecast which is is good agreement with the GFS forecast. We are paying attention to the Atlantic side right now but there has been a very strong MJO wave that moved from the Indonesian sector to the west Pacific sector. There has also been persistent ridging in the east Pacific driving storms and atmospheric wave energy towards the Bering strait. This has set up the powerful wave 2 event which is coupling the troposphere with the stratosphere.

The models are not destroying the vortex on the north American side so don't expect a very cold spring and May - June storminess like 2013. This will be a strong splitting event, but I don't think it will cause persistent stratospheric subsidence over the pole like we saw in 2013. The stratospheric subsidence will shorter lived than 2013 it and will be mostly over northern Siberia.

Note that the surface winds and sea surface height gradients will continue to favor more cold fresh water export than normal through the CAA. Water from the Beaufort gyre's fresh water pool has been released to the Labrador sea for the past 15 months or more. I don't think the transpolar drift has been entirely disrupted but fresh water and sea ice have been substantially diverted towards the Labrador sea.

The figure shows extremely high heat flux for wave 2 on 10February18.

Ice Shieldz

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Re: The 2017/2018 freezing season
« Reply #769 on: February 05, 2018, 06:32:00 AM »
Fish - Thanks for that most interesting clarification. Also, fascinating how the tropics affect the Arctic via the MJO. It was 5 days ago where we had the 'highest amplitude MJO event on record (back to 1979) over the West Pacific.'  https://twitter.com/NWSCPC/status/958796146952015872

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #770 on: February 05, 2018, 09:49:40 AM »
The current cyclone was down to 952 hPa at midnight according to Environment Canada:

http://GreatWhiteCon.info/2018/02/the-february-2018-fram-strait-cyclones/#Feb-05
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Alexander555

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Re: The 2017/2018 freezing season
« Reply #771 on: February 05, 2018, 12:27:46 PM »
I dont know how reliable it is, but the pic for Saturday is 942 hPa. And a few days later the lowest i see is 931 hPa.

A-Team

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Re: The 2017/2018 freezing season
« Reply #772 on: February 05, 2018, 12:34:09 PM »
Quote
need some new thoughts on how the Arctic Sea Ice drifts
In part because the Bering Strait still has a high sill of 53m at current sea level, relatively little Pacific water, none deep, enters the Arctic Ocean relative to inflows of Atlantic Waters which contribute ~10x the volume. Since the volume of the AO is not increasing, an equal volume exits after circulating (for years) as bathymetric boundary currents. These are hundreds of meters below the surface and do not transport ice whose motion sums wind-driven and near-surface currents.

Moorings set by A Muenchow have measured the Nares component of AW export (which cannot be confused with PW). Increasing Atlantification far along the Siberian side, again documented with mooring and profiler data, is captured quite well in MercOcean displays even at (storm affected) 30 m depth whereas less influence is seen from the Pacific.

From my perspective, there's no further purpose served in discussing the non-operative Transpolar Drift. The eight consecutive years of ASCAT imagery (up-forum) prove conclusively that the ice does not move in that manner in the seasons covered. This imagery has far too many internal controls to be mis-interpretable.

That is why TPDrifters don't post satellite time series supporting their views -- there aren't any. However journals keep it alive -- entrenched scientific ideas change one funeral at a time.

It's nonetheless interesting to consider how the ice moved in the past, for example during the 100,000 years that the Pacific and Arctic oceans were disconnected by Beringia. Inflows began at 11,000 BP as ice sheets melted but these must have been initially incremental. Meanwhile a km thick central ice pack was leaving scours on the Lomosonov Ridge and a vast ice sheet over the Barents Sea was melting out.

We can't very well discuss future ice motion since the AO will be ice-free but intermediate years with a smaller, thinner and seasonably variable ice pack will be susceptible to unforeseeable weather, winds and long-fetch waves. Oceanic circulation in an ice-free Arctic? Most of the model effort goes into what will happen with the AMOC heat re-distribution.

The inset animation tracks the motion of a curious feature (virtual buoy) from the Sept minimum until early February 2018. The first frames show the unexplained polynya off the Laptev that had many posts this summer flanked by horns of brighter ice, presumably MYI.

Over time, the feature remains quite recognizable despite moving indecisively towards the Fram while experiencing considerable deformation (stretching). However I expect winds associated with this storm to measurably deflect the feature towards the CA/AK.

Technical note: the ASCAT map projection is conformal, conserving angles but not areas; map scale changes with distance from the pole, making quantitative shape change measurements problematic.

Normal buoys are point-like objects, usually very few in number, placed in floes in late spring followed shortly by high attrition. Virtual buoys are free and dense in coverage throughout the year, providing dimensional extent and orientation which allow tracking of position, rotation and deformation for years at a time. If someone looks at the data.

Although we are seeing Arctic DEMs and bathymetry in netCDF format, this has not yet been used to store images probably because png provides extensive lossless compression. However applying ncgen to a 8-bit grayscale value geolocated grid like an ASCAT image would offer some advantages, like instant application of the 100+ map projections of Panoply (some equal area), instant false coloring with the 100+ palettes, and quantitative inter-operability with whatever other Arctic data is in netCDF format.
« Last Edit: February 05, 2018, 04:21:03 PM by A-Team »

Pmt111500

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Re: The 2017/2018 freezing season
« Reply #773 on: February 05, 2018, 01:12:23 PM »
Oh, Transpolar Drift has stopped working?!? Front cover story, renew the front page!   ;D 8) :P. Thanks also for the rest of 'current studies on currents'-newsflash. The Atlantification of Arctic Ocean has clearly progressed further in recent years, yes.
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Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #774 on: February 05, 2018, 01:23:26 PM »
A Sentinel 1B SAR image of the ice edge yesterday:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

romett1

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Re: The 2017/2018 freezing season
« Reply #775 on: February 05, 2018, 02:32:45 PM »
Waves currently north of Svalbard according to ECMWF.

A-Team

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Re: The 2017/2018 freezing season
« Reply #776 on: February 05, 2018, 04:44:21 PM »
Quote
Oh, Transpolar Drift has stopped working?!? Front cover story!
As mentioned, TPDrifters never post evidence supporting their views, though nothing could be easier. It seems for recent years, there isn't any. They just keep repeating what they were taught long ago in school, even in the face of conflicting current data.

Many floe tracks do exit the Fram, others the Nares, still others via the Barents islands or CAA garlic press (like the single functioning Obuoy), and in recent days, some left to the south out to the Bering Sea (reverse TPD?) per Modis. Many central traces never leave, they simply mill about or stall for as long as they can be followed.

We followed the journey of Big Block over many months up the AK coast before it stalled, broke up and melted out in the warmer Chukchi. Six of the last eight years have shown the same local pattern. The 'goat's head' too was followed for a long time in an earlier winter.

This year, Fram exiting was practically non-existent during the summer and early fall but picked up suddenly around day 298 (Oct 25th). That can be seen on either on Ascat or the Piomas volume export chart that wipneus posted the day before:



Fram export area this fall, winter and spring will be dominated at the 85% level by export of the Kara Sea intrusion, ice that was formed there in late October (TMI or third month ice). Some FYI from the Laptev will also contribute, as it often has in recent years.

Additionally, small but thick areas of Greenland and CAA-flanking ice will exit, along with some deformed central ice. These later losses play a disproportionate role in pinching out trends to zero in multi-year ice age class proportions.

Not a single floe from the Beaufort-Chukchi-ESAS western sector is at risk of TPD transport out the Fram/Barents/Nares over the July 2017 to May 2018 time frame. Disagree? Show me the floe.

It would be great to have nullschool-like sprites tracking ice movement. These feature sprites would initiate, flow along their variable length path for variable lengths of time, terminate upon breakup, melt or exit.

Buoys can contribute multi-year drift tracks but there aren't nearly enough of them. Worse, there are very significant biases in shipboard release position, season of installation and cessation of function.

It is easy to automatically characterize day-on-day ice movements but much harder to do path integrals of the resulting velocity vector field. That's because there's not necessarily ROI handoffs one day to the next.

However fancier (but still sub-optimal) contrast post-processing (up-forum mp4) reveals a near-saturation density of potential sprites lurking in ordinary Ascats. It doesn't seem very dignified to track these manually but in fact it can be done very rapidly in ImageJ. That's because it's primarily cell biology software and those scientists have forever been wanting to track movement of cells and interior stained features, so it's been developed to the nth degree of convenience (in 5D no less).

TPD is ill-posed, boring. It is the sprites product that is needed. From that trajectory database, the rest follow: convergence, divergence, deformation, volume loss by thickness class, etc. From there, comparative mobility measures.

Below, the image flicker from the two past days (before full storm onset) show significant one-day movement of the pack in the direction expected from strong persistent winds, 'ENE' to 'SSW' as the map is laid out. Indeed there seems to be a central swath of deformation, not just bulk translation, between essentially stationary ice. Sentinel-1AB can differentiate between shear and plastic deformation along the interfaces.

Technical note: 16-bit 3-channel Sentinel-2AB revolutionized cryosphere imagery processing (unlike land scenes, ice is basically white on white). Ascat is offered as 24-bit color png but the three channels are identical, thus it is really 8-bit grayscale. The question is, does changing to 16-bit gray in ImageJ options prior to global and locally aware contrast stretching bring any benefit? That could nuance two intermediate round-off steps but ultimately the monitor will be displaying an 8-bit gif. So the gains may be modest except when zeroing on in special small regions where every bit helps.
« Last Edit: February 05, 2018, 10:53:59 PM by A-Team »

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #777 on: February 05, 2018, 04:53:17 PM »
As the big storm moved up through the Fram, west winds have pulled the ice away from the east coast of Greenland at Joekelbugt.


Michael Hauber

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Re: The 2017/2018 freezing season
« Reply #778 on: February 06, 2018, 02:26:24 AM »


Fram export area this fall, winter and spring will be dominated at the 85% level by export of the Kara Sea intrusion, ice that was formed there in late October (TMI or third month ice). Some FYI from the Laptev will also contribute, as it often has in recent years.

Not a single floe from the Beaufort-Chukchi-ESAS western sector is at risk of TPD transport out the Fram/Barents/Nares over the July 2017 to May 2018 time frame. Disagree? Show me the floe.


I thought transpolar drift was primarily drift of ice from Laptev towards Fram Strait, which you seem to acknowledge occurs.    And not ice from Beaufort or Chukchi,  Maybe ESS.  Wikipedia defn

Edit:  Polar bouy tracks seem to provide significant support.
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #779 on: February 06, 2018, 02:37:17 AM »
A-Team, for your amusement I have a reference from your favorite science source, the Daily Mail.
http://www.dailymail.co.uk/news/article-464768/Thousands-rubber-ducks-land-British-shores-15-year-journey.html


Thousands of rubber ducks to land on British shores after 15 year journey

By BEN CLERKIN

Last updated at 22:00 27 June 2007

They were toys destined only to bob up and down in nothing bigger than a child's bath - but so far they have floated halfway around the world.

The armada of 29,000 plastic yellow ducks, blue turtles and green frogs broke free from a cargo ship 15 years ago.

Since then they have travelled 17,000 miles, floating over the site where the Titanic sank, landing in Hawaii and even spending years frozen in an Arctic ice pack.

And now they are heading straight for Britain. At some point this summer they are expected to be spotted on beaches in South-West England.

While the ducks are undoubtedly a loss to the bath-time fun of thousands of children, their adventures at sea have proved an invaluable aid to science.


I'm not going to argue for or against the transpolar drift because these days an individual ice floe would melt before it crossed the Arctic, but how about these rubber duckies that made it from the Pacific to the Atlantic through the Arctic ocean? I'm not sure what we call it but there is some through flow from the Pacific to the Atlantic.

Niall Dollard

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Re: The 2017/2018 freezing season
« Reply #780 on: February 06, 2018, 09:14:47 AM »
That's very good, Fish.

It's a nice graphic but likely incorrect in showing the ducks taking a track to the east of Iceland, when it would be far more likely to bob along with the East Greenland Current to the west of Iceland.

but how about these rubber duckies that made it from the Pacific to the Atlantic through the Arctic ocean? I'm not sure what we call it but there is some through flow from the Pacific to the Atlantic.

How did they do it ? They made their way through the large quacks in the Duckchi Sea, of course.

I'll get my coat...... :D


Phil.

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Re: The 2017/2018 freezing season
« Reply #781 on: February 06, 2018, 11:54:19 AM »

gerontocrat

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Re: The 2017/2018 freezing season
« Reply #782 on: February 06, 2018, 03:17:14 PM »
With all eyes on Rubber Quacks, (it took 8 years to cross from the Bering Strait to the Fram - not much of a transpolar drift), I had a look at the Pacific end. It seems above freezing in the Bering Sea and right up into the strait - warmish winds from the south. Not much new ice to form there, if any?
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A-Team

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Re: The 2017/2018 freezing season
« Reply #783 on: February 06, 2018, 03:51:17 PM »
Here are two variant visualizations of the two-day motion attributable to the storm. These compare the 3rd to the 5th of February. The wind power density on the 4th is also shown at the surface; for reasons explained way up-forum, this may be more appropriate to momentum transfer than wind speed per se.

Along the central swath of WPD, the displacement is ~45 km which is about a km per hour. It would take 62 days at this rate for the white star to reach the MacKenzie Delta. Current conditions will persist for only a few more days however.

Not all the ice is moving in that direction by any means; there are even fixed points. Along the CAA, the movement is eastward. Some of that is attributable to local wind direction but the rest is deformation in response to the central swath. Poleward motion of the Kara tongue then squeezes ice above Morris Jesup out the Fram.

Technical note: The Ascat sea ice product is ironically a byproduct of its primary purpose which is wind speed measurement over the oceans. However nullschool does not use that data directly (or indirectly?) for its wind maps. That's unfortunate for synchronicity: the 4 hour GFS intervals are then not tied to timing of the EUMETSAT MetOp-A orbital swaths that generate the daily Ascat posted at Noaa.

The other issue with this is masking rain and open water on the Arctic Ocean perimeter that make Ascat sequences are quite flashy in the Bering Sea and Chukchi for reasons unrelated to sea ice. This is also a huge problem along the eastern Fram and Barents Edge.

It's possible however to pull out a one-time land mask (which Ascat does not provide) plus daily open water masks from UH AMSR2 3.125 km determinations of sea ice concentration. These are readily applied to Ascat images to cover up everything but the ice (to whatever concentration bound), thus better displaying effects of the storm. Here again the swath timings of these products are difficult to match as only the former is in the A-train satellite constellation.

It is critical here to get the AMSR2 rescaled to match the unstated scale of Ascat because of narrow island passageways and straits. Both use the same projection and orientation and both extend out to the 45th parallel (look for upper Lake Michigan). That means the two diameters can be measured to very low error; the correct downscaling of AMSR2 then follows, as does coincident alignment of north poles (not marked on Ascat).

These operations easily scale to thousands of image pairs, so to the entire joint record. While we could use it during this storm, a more important application may be to the summer melt season when Ascat imagery has so many weather distractions that feature sprites are difficult to maintain.

Since there is effectively no scientific presence on Arctic sea ice for nine months a year, it is important to wring every last bit of information out of what satellite data is available from radar windows.

Here masking out both land and open water artifacts allows gathering of daily contrast statistics that can rationally and reproducibly optimize image enhancement, though the human perceptual component can never be disregarded especially with indexed color palettes. Algorithmic determination of deformation also greatly benefits from prior region-of-interest enhancement.

Once superimposed, the AMSR2 could also be used as a second color channel to Ascat. For that a proper Geo2D netCDF is needed so that concentration could be represented as grayscale. Seasonally, SMOS ice thickness could be used as a third channel. Color would provide vastly improved feature discrimination. Alternatively, Ascat grayness amounts to a DEM upon which AMSR2 or SMOS can be draped as a hillshaded surface.

However at the end of the day, Ascat provides only 86,500 = 294*294 pixels for the Arctic Ocean proper (which is 380x330 as a Greenland-down rectangle). That's an 8.3% payload out of the initial file. It would be great to have twice the resolution or 16-bit sensitivity but those may not arrive before the ice is gone.

http://www.remss.com/missions/ascat/ best source of Ascat technical information
« Last Edit: February 06, 2018, 05:19:09 PM by A-Team »

jdallen

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Re: The 2017/2018 freezing season
« Reply #784 on: February 06, 2018, 11:33:19 PM »
With all eyes on Rubber Quacks, (it took 8 years to cross from the Bering Strait to the Fram - not much of a transpolar drift), I had a look at the Pacific end. It seems above freezing in the Bering Sea and right up into the strait - warmish winds from the south. Not much new ice to form there, if any?
I think the key right now won't be the effects on extent and area, rather what will happen to both net heat flow out of the water and general ice thickening over the next six weeks.  It seems to me the timing of the vortex split couldn't be worse, as it will encourage the creation of strong spring storms on the Atlantic side that will drag both latent and direct heat into the basin.
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FishOutofWater

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Re: The 2017/2018 freezing season
« Reply #785 on: February 07, 2018, 12:49:15 AM »
All of Alaska has now seen the first dawn of the new year. NASA Worldview visible images show thin, weak floes moving through the Bering strait into the Arctic ocean over the past few days at the same time southerly winds pounded the Atlantic side of the ice pack.

Arctic oceanography models have have predicted increasing flow through the CAA as the Arctic warms and the ice thins. I have no doubt that we have seen that happen over the past 2 years and that this weather will continue that trend. The buoy in the main channel of the CAA is the closest thing we have today to rubber duckies.

Close examination of the Mercator ocean salinity maps, from 0 to 100 m depth, over the past 2 years has led me to conclude that a large amount of fresh water stored in the Beaufort gyre has been released through the CAA over the past 15 months.

The atmospheric wave 2 pattern in the NH driving the polar vortex splitting event may be amplified by the lack of sea ice to the SW of the Bering strait and the deficiency of sea ice in the Barents sea. I think we are now seeing coupled ocean/atmospheric processes associated with declining Arctic winter sea ice.

Ice Shieldz

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Re: The 2017/2018 freezing season
« Reply #786 on: February 07, 2018, 01:44:10 AM »
Zoom in on sea ice movement for 02/04 thru 02/06 at Cape Morris Jesup (northern tip of Greenland). Rough estimate of 46 miles (74km) of travel for one tracked section of ice.

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #787 on: February 07, 2018, 06:30:09 AM »
Are there going to be ANY functioning webcams in the Arctic Ocean this year?
http://obuoy.datatransport.org/monitor#overview/gpstracks

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #788 on: February 07, 2018, 10:49:27 AM »
Are there going to be ANY functioning webcams in the Arctic Ocean this year?

Maybe?

http://imb-crrel-dartmouth.org/imb.crrel/newdata.htm
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A-Team

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Re: The 2017/2018 freezing season
« Reply #789 on: February 07, 2018, 01:05:50 PM »
The storm is bringing amazing displacements and deformation of the ice pack. For meridional scale, Ushakov Island is 1021 km from the north pole. (That's the island between SZ and FJL that has been providing the rubble ridges as Kara Sea ice moved past into the Arctic Ocean. Those white streamers have provided directly visible motion trajectory records -- sprites -- for the last four months but now are deforming badly.)

The first derivative of the image sequence shows the central swath displacement from SZ right up over the pole and down towards Amundsen Gulf. The Chukchi and ESAS are not participating to any extent, just milling about. (The proprietors of Ascat have normalized the backscatter of its C-band radar to a bounded geolocated scalar field, the daily grayscale.)

This storm does not seem that remarkable compared to ones last year in terms of TPW advection.

The final animation shows overall motion as viewed from a North Atlantic perspective.

It's also of interest to match up wip's animation of the last 3 months of Piomas thickness with Ascat's perspective on where the thick ice resides and how it has been moving.

Piomas could be used to determine and track the motion of the icepack's center of mass which might be used with the moment arm of wind power density to torque ice pack rotation. However GFS has completely changed its story today, meaning a ice movement forecast based on yesterday's depiction would already be worthless.

The Arctic Ocean is very much constrained by the particulars of its basin so it's worth looking at a change of radial coordinates to PS centered at 85.8N, 176.15E to see if that fits Ascat motion better. The largest block of ice that can rotate freely is 2016 km in diameter touching Ellesmere, Komsomolets and Genriyetta islands. The lat lon grid is easy to draw in Panoply and overlay on Ascat mp4's. https://doi.org/10.1017/S003224741300051X
« Last Edit: February 07, 2018, 02:06:18 PM by A-Team »

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #790 on: February 07, 2018, 02:04:26 PM »
It may take a while for me to get the animation working on the forum, but here's AMSR2's overview of the side effects of the recent cyclone:

http://GreatWhiteCon.info/2018/02/the-february-2018-fram-strait-cyclones/#Feb-07

PS. Just clicking the GIF image seems to do the trick.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #791 on: February 07, 2018, 02:14:05 PM »
The latest Arctic Sea Ice News:

https://nsidc.org/arcticseaicenews/2018/02/sea-ice-tracking-low-in-both-hemispheres/

Quote
January of 2018 began and ended with satellite-era record lows in Arctic sea ice extent, resulting in a new record low for the month. Combined with low ice extent in the Antarctic, global sea ice extent is also at a record low.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

A-Team

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Re: The 2017/2018 freezing season
« Reply #792 on: February 07, 2018, 02:24:39 PM »
Thx Jim, very helpful.

The leeward polynyas are coming in as expected. 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). There's some nice Sentinel-1AB passing by at http://www.seaice.dk/latest/; the one below needs a click to display at the provided resolution.

« Last Edit: February 07, 2018, 02:41:27 PM by A-Team »

magnamentis

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Re: The 2017/2018 freezing season
« Reply #793 on: February 07, 2018, 04:34:34 PM »
The latest Arctic Sea Ice News:

Quote
January of 2018 began and ended with satellite-era record lows in Arctic sea ice extent, resulting in a new record low for the month. Combined with low ice extent in the Antarctic, global sea ice extent is also at a record low.

this and the lack of extraordinary cold weather above in places where is ice now, more the opposite, it was way warmer than average, i have (like so often before) my serious doubts about sea ice volume numbers. record or close to record lows in area and extent almost permanently and how should the volume be significantly higher than last year? after all the ice which is now in place would have to be much thicker than last year despite the fact that it's permanently as warm or warmer.

i still believe that in the not so far future we shall see massive changes/correction in piomas algorithms, too many times things don't look right or intuitive other than the general trend which is correct but then obvious and undeniable as well.
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Sleepy

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Re: The 2017/2018 freezing season
« Reply #794 on: February 07, 2018, 05:46:54 PM »
Here goes the PV...
Omnia mirari, etiam tritissima.

Thomas Barlow

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Re: The 2017/2018 freezing season
« Reply #795 on: February 07, 2018, 10:02:39 PM »

werther

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Re: The 2017/2018 freezing season
« Reply #796 on: February 07, 2018, 10:03:56 PM »
Small contribution. Good animation by Jim Hunt, showing the impact of that Low.
I don't want to put in as much time as I did some years ago. But still keeping an eye on the main events.
NCEP NCAR comparisons do show this winter's power sliding to levels seen during '15-'16, which is a bad sign. Chukchi region is worse, Atlantic side still a bit better than then.
Rest of feb left to change things for the better...

Jim Hunt

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Re: The 2017/2018 freezing season
« Reply #797 on: February 07, 2018, 11:31:27 PM »
Thanks !

It's by no means certain I'm afraid. Most years an IMB buoy with associated webcams gets installed near Barneo in April. Sometimes the other IMB buoys have a webcam pointed at them, but more often they don't.
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A-Team

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Re: The 2017/2018 freezing season
« Reply #798 on: February 07, 2018, 11:58:53 PM »
Quote
i have serious doubts about sea ice volume. lows in area and extent almost permanently how should the volume be significantly higher it's permanently as warmer. we shall see massive changes/correction in piomas algorithms, too many times things don't look right.
That view may be widely shared in the scientific community. Otherwise, why continue to pursue observational ice thickness, like Cryosat, Topaz, SMOS, and do all the field work? In my view, UH SMOS is the most accurate -- and most disturbing -- of the bunch (in its speciality, the thinner ice). However ice thickness may be heading to a hybrid product that integrates Cryosat, Piomas, and SMOS.

Some cross-posted images from the Piomas forum around #2268:

« Last Edit: February 09, 2018, 10:18:01 AM by A-Team »

Sleepy

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Re: The 2017/2018 freezing season
« Reply #799 on: February 08, 2018, 08:41:20 AM »
Adding animated ECMWF forecasts for 20mb and zonal mean winds to that hindcast in #794.
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