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Author Topic: The 2016/2017 freezing season  (Read 391796 times)

slow wing

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Re: The 2016/2017 freezing season
« Reply #50 on: September 15, 2016, 02:16:58 AM »
Yes, it's a strong storm and an interesting question whether it could potentially reverse at least some of the refreeze.

Currently near the North Pole and at 988 hPa, GFS at Tropicaltidbits predicts it to bottom out in around 36 hours, at 976 hPa, and to endure for about a week at below 990 hPa, located in the Arctic Basin and mainly off the Canadian Arctic coast.

What will that do to the newly formed refreeze ice?  :-\
« Last Edit: September 15, 2016, 02:24:05 AM by slow wing »

Shared Humanity

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Re: The 2016/2017 freezing season
« Reply #51 on: September 15, 2016, 04:44:08 AM »
Animation is on the right thread and studying winter storms in the new Arctic is certainly worth the effort. With all of this open water, storms should be able to pull energy from the ocean and affect the freeze in ways that the ice covered Arctic of the 1980's would not have allowed.

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #52 on: September 15, 2016, 02:18:34 PM »
GFS shows the cyclone persisting in the 970-980 hPa range for 120 hours starting later today (actually two lows with a brief 18h of minimum above 980 hPa in between).
ECMWF predicts a cyclone somewhat weaker.


be cause

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Re: The 2016/2017 freezing season
« Reply #53 on: September 15, 2016, 02:25:56 PM »
GEM was well ahead in predicting current developments . At the moment it's 240 has a central Arctic storm below 960 ! 

Anyway enjoy the journey through the Northern winter and thanks to all on board for the science and opinions shared . bc
be the cause of only good
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will .. through you .. transform all nations :)

Shared Humanity

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Re: The 2016/2017 freezing season
« Reply #54 on: September 15, 2016, 03:16:01 PM »
Last winter I lamented the fact that so many regular visitors disappeared. I spent the entire winter here and it was an amazing winter indeed, a record low maximum. I understand that the Arctic summers can be riveting but if we really want to understand how AGW is affecting the Arctic, it is just as important that we follow the Arctic winter. This includes the large positive anomalies for NH snow cover in the winter, the rapid melt of that same snow so that we have huge negative NH snow cover anomalies in the Spring. How are the warm Arctic Winters and the large stretches of open water contributing to these anomalies? What effect might these early snow blankets have on the thawing permafrost as it insulates the permafrost from the winter cold? It can't be good as it can only increase the areas of discontinuous permafrost. What about deep snow cover on the refreezing ocean. Wouldn't this also inhibit the growth of the sea ice in the winter?

What do stormy fall seas mean for the freeze season. How might it alter the nature and quality of FYI? I am fascinated by waves and the emerging physical structures we find in the sea ice, widely fractured with less and less ice that can be found as huge, very stable and relatively immobile flows. I believe our mild winters, later freezes and newly stormy winter Arctic has a dramatic impact on the physical nature of the ice, its integrity and the nature of the following melt season.

This melt season was riveting. I expect this winter freeze season to be as well.

Pass the popcorn.

budmantis

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Re: The 2016/2017 freezing season
« Reply #55 on: September 15, 2016, 03:34:59 PM »
This melt season was riveting. I expect this winter freeze season to be as well.

Pass the popcorn.

I'll take mine with extra butter! I like your post SH and by this time every year, I quickly lost interest in the Forum once the minimum was declared. I plan on hanging around through the winter as I've discovered there is more to Arctic sea ice than the melt season.
"To predict the behavior of ordinary people in advance, you only have to assume that they will always try to escape a disagreeable situation with the smallest possible expenditure of intelligence." Nietzsche

oren

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Re: The 2016/2017 freezing season
« Reply #56 on: September 15, 2016, 03:38:06 PM »
This melt season was riveting. I expect this winter freeze season to be as well.
Great post SH. I think it would be useful to put a copy on the melting season thread too, for those who only read it and not much else.

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #57 on: September 15, 2016, 05:57:22 PM »
We're definitely in the freezing season now, so here's the Kap Morris Jesup area from the 13th:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201617-images/#CAB
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Andreas T

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Re: The 2016/2017 freezing season
« Reply #58 on: September 15, 2016, 09:09:06 PM »
the characteristic "shades" of  more recent and older leads are now showing where water that has been exposed for longer than a couple of days is gaining an ice cover visible in the satellite image.

Oden, on the way south further east is reporting air temperature of -8.6 with a northwesterly (290) wind http://www.sailwx.info/shiptrack/shipposition.phtml?call=SMLQ

Feeltheburn

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Re: The 2016/2017 freezing season
« Reply #59 on: September 15, 2016, 10:43:45 PM »
My point, however, was not to repeat the "seed crystal" analogy but rather to respond to a point made by someone else that dispersed ice should hasten melting.   

Completely contrary both to fact and what's been presented.  Very simply - dispersed ice means greater surface area exposed to heat, both directly through side melt and indirectly via increased uptake of heat from insolation, or, heat retrieved from depth via increased circulation caused by movement (Ekman pumping).  There is more to it, but just these facts break your hypothesis.

Two words:  Hysteresis and Enthalpy.  Systemically , how conditions change over time in the arctic - including the mechanics of re-growing the Arctic pack suffer from Hysteresis - the way the system changes lags behind those supported by current forces in play.

Secondly we have enthalpy - the total heat in the system - which has increased monstrously over the last 3 decades and that increase is accelerating, due to increased input of heat into it from multiple sources which are catching up with changing conditions; and Further, is not being reduced in the refreeze season at a rate which offsets the new inputs.  The heat we had last winter with the absurdly low ice maxima and 30C+ positive temperature anomalies is testimony to that.  I actually found that far more terrifying than the collapse of the pack in 2012, and I think it may be just as significant, if not more.

Dispersed ice will have virtually no effect one way or another on the refreeze.  It will be governed entirely by two things - the current enthalpy of the system, and how fast the system can transport that heat out of the top of the atmosphere.  In this, the formation ice is a net hindrance, as it reduces circulation, convective transfer and evaporative transfer of heat.  Conduction through ice is a poor replacement.  I'd say hope for cold temperatures and open water as long as possible.  It's how the ice will be preserved.

Wonderful explanation!  To summarize.  Your points regarding hysteresis, enthalpy, rate of heat transfer, circulation, and conduction means that the highly dispersed ice we saw in summer of 2016 will not per se affect the rate at which ice melts during the melt season nor the rate at which it refreezes during the refreeze season.  The ice dispersal is merely a symptom, not a cause, of the totality of the system.  If true, that refutes the point I was refuting in the first place.  Thank you for the assist.  :)
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Feeltheburn

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Re: The 2016/2017 freezing season
« Reply #60 on: September 15, 2016, 11:11:49 PM »
Anyway, to summarize the arguments and the observed data.  Andreas T and JD Allen stated that the highly dispersed ice would not affect the rate of ice refreezing because the rate of ice refreeze is dependent upon more important factors.  The converse also appears to be true, and it was borne out by the behavior of the ice this summer, that the highly dispersed ice does not and did not affect the rate of ice melt but was merely a symptom of the state of the overall system.

The ice extent through June-August held up better than predicted when it was near record lows earlier in the melt season during March-May.  (Sorry Professor Wadhams - Arctic ice lives at least one more year!)  The fast drop near the end of the melt season occurred after the Arctic cyclone, meaning that the drop was mainly the result of compaction and some Fram export rather than accelerated melting due to highly dispersed ice.  The hypothesis I was commenting on was by a poster who stated that highly dispersed ice has higher surface area exposed to water and air capable of melting ice and that this should hasten the rate of ice melt.  Obviously it didn't based on the record, and this is consistent with the fine explanations provided by Andreas T and JD Allen.
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Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #61 on: September 15, 2016, 11:54:02 PM »
The latest cyclone is down to 980 hPa:

http://weather.gc.ca/analysis/index_e.html
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #62 on: September 16, 2016, 12:44:22 AM »
There is a reason to believe dispersed ice (or a greater extension of broken ice edge) may have an initial positive impact on refreezing, and is that a big deal of the refreezing is seen to proceed as a propagating front.
Without entering into what the fundamental causes of this propagating nature can be, any process that evolves by propagation is initially more abundant the longer the initial interface is.
However as soon as the many propagation fronts gradually merge into two or three main fronts around the ice pack, there is no longer much difference regardless of the initial perimeter of the interface.
As I have been reading stuff about marginal ice zone lately (I posted a couple of refs in other comments sorry I am lazy) it may happen as well that a highly broken and extended edge may benefit (to some measure) faster loss of ice extent at the end of the season. The reason is quite different. It seems that the zone of very broken ice floes at the periphery of the pack exhibits a self-similar distribution of floe sizes after enough floe break-up has been caused by waves, winds, currents... That is, as you zoom in, you see a picture of dissimilar floes that in proportion look the same, whether the frame is 50km x 50km or 500m x 500m. As time goes on, the rate of floe meltout is highest for the smallest floes, while the bigger floes keep splitting without losing much area. Therefore a big proportion of the melting happens at the small-scale end of this distribution. This amount of floe breakup and final meltout is more abundant the more dispersed the pack is at the edges by August. Wasn't this stormy melting season, less dominated by surface melting, a good example?
« Last Edit: September 16, 2016, 01:40:03 AM by seaicesailor »

icy voyeur

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Re: The 2016/2017 freezing season
« Reply #63 on: September 16, 2016, 08:06:37 AM »
Random thoughts about what makes for a good freezing season, and pondering the start of the refreeze and what might be some wind driven compaction: maybe this is a good start?
Maybe a few sessions of making ice followed by winds to pile it up and free up more surface? All the better to radiate away more of the ocean's heat? Of course the total latent heat is of the big concerns but what better way to let it radiate away than to have cold dry winds suck up moisture and pile up ice to free up surface water? Just late night musing.

Shared Humanity

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Re: The 2016/2017 freezing season
« Reply #64 on: September 16, 2016, 02:46:22 PM »
I am not sure these storms bring cold dry winds. Wouldn't this new stormy, warmer, winter Arctic be generally evidence of increased moisture? The polar region has been anomalously warm for a number of winters, north of 80 degrees. I expect this to continue. With the periodic collapse of the vortex and an increasing number of intrusions from the mid latitudes, I have to believe that humidity, dew points and precipitation in the polar region are on the rise. We are seeing large positive anomalies in NH snow cover. Isn't this evidence of increased moisture content?

Someone here said that increased moisture in the atmosphere brings a great deal more energy than higher temperatures. Did I get this right? Since H2O is a powerful greenhouse gas, acting as a blanket and holding heat in, couldn't this increased atmospheric moisture and cloudiness be contributing to the week freeze seasons we seem to be seeing?
« Last Edit: September 17, 2016, 12:00:55 AM by Shared Humanity »

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #65 on: September 16, 2016, 03:34:14 PM »
The Central Arctic cyclone is now down to 975 hPa MSLP, and I cannot help but wonder where Tropical Storm Ian is heading:

http://GreatWhiteCon.info/2016/09/september-arctic-cyclone-alert/
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

jdallen

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Re: The 2016/2017 freezing season
« Reply #66 on: September 16, 2016, 10:30:35 PM »
The Central Arctic cyclone is now down to 975 hPa MSLP, and I cannot help but wonder where Tropical Storm Ian is heading:

http://GreatWhiteCon.info/2016/09/september-arctic-cyclone-alert/

I think, in so many words:  The Barents Sea

To be followed shortly thereafter by a visit to the CAB.

I'd say the Cyclone Cannon is starting to heat up.
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Shared Humanity

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Re: The 2016/2017 freezing season
« Reply #67 on: September 17, 2016, 12:05:48 AM »
This could be an amazing freeze season.

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #68 on: September 17, 2016, 12:33:19 AM »
Wow did the cyclone strengthen in the Euro forecast too.
Although the storm helps maintain melting power in the open half of the Arctic for a while more, the pack is going to be inflated and cold air spread outwards from the CAB ice core.
The detached ice near Wrangel is really going to take that last beating anyway.

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #69 on: September 17, 2016, 01:17:14 PM »
This is the 5-day averaged GFS MSLP, with a sustained pattern that is not dilute by the averaging. Refreezing should continue advancing outwards from the central pack, but Beaufort sea won't see surface freezing anytime soon. Interesting situation of the detached Wrangel ice, where most probably bottom melting has not ceased yet but surface refreezing is building up. The storm may enhance both antagonistic processes simultaneously in this region...

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #70 on: September 17, 2016, 03:15:43 PM »
Cross posted from the "Melting season" thread.

Another cyclone => more "melting" in the CAB (and elsewhere):


Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Andreas T

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Re: The 2016/2017 freezing season
« Reply #71 on: September 17, 2016, 06:52:05 PM »
A clear view of the sector which had the bite shows the refreeze with ice surface insulating the water surface. The colder ice looses less heat, thicker, older ice less than the younger thin stuff.

switch between IR and visible to see the streaks of ice forming as cold air blows off the ice.
http://go.nasa.gov/2d6habC

Kate

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Re: The 2016/2017 freezing season
« Reply #72 on: September 18, 2016, 02:02:58 PM »
Lots of wind and waves will make the start of this year interesting to watch

Andreas T

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Re: The 2016/2017 freezing season
« Reply #73 on: September 18, 2016, 04:19:06 PM »
To adress the question whether the increase in ice area in the CAB is actual freezing ( new ice  forming at the sea surface) or spreading out of existing ice (Wayne seems to have that idea), I am comparing clear views of the 8th and 16th.http://go.nasa.gov/2d89TI8 The area is the same as in the IR image I posted earlier.
marking recognizable floes I think it is clear that there is a thin layer of ice (the greyish stuff) which appears in addition to the whiter (thicker) ice which can be seen in the earlier shot.

oren

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Re: The 2016/2017 freezing season
« Reply #74 on: September 18, 2016, 05:45:43 PM »
To adress the question whether the increase in ice area in the CAB is actual freezing ( new ice  forming at the sea surface) or spreading out of existing ice (Wayne seems to have that idea), I am comparing clear views of the 8th and 16th.http://go.nasa.gov/2d89TI8 The area is the same as in the IR image I posted earlier.
marking recognizable floes I think it is clear that there is a thin layer of ice (the greyish stuff) which appears in addition to the whiter (thicker) ice which can be seen in the earlier shot.

Excellent stuff. Thanks.

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #75 on: September 18, 2016, 05:49:18 PM »
Lots of wind and waves will make the start of this year interesting to watch


The Barrow webcam is down. If it were working I'm sure it would show some waves. The current forecast:

http://GreatWhiteCon.info/2016/09/september-arctic-cyclone-alert/#Sep-17

HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 6 AM AKDT MONDAY...

* WAVES AND SURF...WAVES TO 10 FEET BREAKING JUST OFFSHORE
  COMBINED WITH TIDES UP TO 1 FOOT ABOVE NORMAL WILL CAUSE HIGH
  SURF CONDITIONS.

* ICE...WITH ICE JUST OFF SHORE FROM BARROW...IT IS POSSIBLE
  THAT CHUNKS OF SEA ICE WILL WASH UP ON SHORE EVEN WITH WINDS
  PREDICTED TO BE AT NEARLY PARALLEL TO THE SHORE.

* WINDS...WEST 20 TO 30 MPH THROUGH EARLY MONDAY MORNING.

* TIMING...HIGH SURF IS EXPECTED TO CONTINUE THROUGH EARLY
  MONDAY.

* IMPACTS...HIGH SURF WILL WASH TO THE TOP OF THE BEACH AND
  CAUSE BEACH EROSION. MINOR FLOODING OF LOW LYING AREAS IS
  POSSIBLE AND SURF COULD WASH ONTO LOW LYING ROADS NEAR THE
  BEACH.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

A-Team

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Re: The 2016/2017 freezing season
« Reply #76 on: September 18, 2016, 10:39:44 PM »
is ice in the CAB is new (forming at the sea surface) or old (existing ice spreading itself out) or some of both (what mix? are proportions stable?)
S2A had a clear view twelve days back looking north from Nansen Sound (between Ellesmere and Axel Heiberg). These images are very large because of the high resolution. It is tiled below from south to north.

It would be very instructive to continue the direction of your researches using all the applicable resources, especially color for S2A 10m.

Andreas T

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Re: The 2016/2017 freezing season
« Reply #77 on: September 19, 2016, 08:52:41 AM »
Those closeups of ridged floes are interesting but to address the larger scale process your animation of UH AMSR2 is more useful
...


The expansion of the low concentration area while higher concentration features hardly move (at that scale) in the same direction is showing the same as the MODIS images above.

ghoti

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Re: The 2016/2017 freezing season
« Reply #78 on: September 19, 2016, 04:25:39 PM »
Look at the ground level photos by Wayne this week on his blog post:

http://eh2r.blogspot.ca/2016/09/vast-expansion-of-scattered-sea-ice.html


He shows areas of floating snow between established sea ice. It is a pretty clear example of how a September snowfall can result in fast expansion of first year ice area. I suppose you can debate whether the floating snow should be considered sea ice or not but it probably will freeze solid very quickly under cold calm conditions and much earlier than open water without snow.

Andreas T

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Re: The 2016/2017 freezing season
« Reply #79 on: September 19, 2016, 07:42:31 PM »
Thanks for that link, ghoti, this helps to form an idea what it is we are looking at here. Given that the IR image shows lower brightness temperature for the grey areas I think it is more than a bit of snow floating in the water. But it is easy to imagine how cold air blowing from the cold ice further north has an easier job turning floating slush into ice than it has with salty sea water.

johnm33

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Re: The 2016/2017 freezing season
« Reply #80 on: September 19, 2016, 09:28:55 PM »
Reinforcing Waynes point, plenty of ice

not so much

A-Team

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Re: The 2016/2017 freezing season
« Reply #81 on: September 20, 2016, 01:13:24 AM »
Here is 2015 from Sept 1st through Oct 31st, with the 18 Sept 2016 shown as green boundary. The pole hole flashes red on the 19th of Sept in the 2015 time series.

It's not so easy to get that 18 Sep 16 bounding mask right because of how the boundary operator fill works in gimp (dithers both boundaries slightly) so it's just attached.
« Last Edit: September 20, 2016, 03:32:35 AM by A-Team »

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #82 on: September 20, 2016, 01:58:56 AM »
Those of you who are, like me, following the exploits of the yacht Northabout on her "Polar circumnavigation" might be interested to learn that the BBC used an interview with  David Hempleman-Adams, leader of the Polar Ocean Challenge expedition, to promulgate the views of the 5th Viscount Ridley, the world famous "Science writer"/"Coal Baron" and destroyer of Northern Rock:

"Radio Four in Arctic Sea Ice Bias Shock Today!"

At this juncture you might have supposed that one or more of those “hundreds of scientists” might have been mentioned, but you would have been wrong.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Archimid

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Re: The 2016/2017 freezing season
« Reply #83 on: September 20, 2016, 03:28:06 PM »
I hope some remnants of big block can hold on for a couple more weeks. If they do, then I expect them to seed ice growth in the Beaufort. If that happens, then ice growth should speed up significantly since it will be growing from different fronts.

As we approach nearly ice free conditions, "big blocks" of ice could be pushed to strategic locations around the arctic to seed ice growth. This should give the freezing season a head start, maximizing ice production in the freezing season. The more ice produced in the freezing season, the more "negative heat" we can store for summer. 
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

6roucho

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Re: The 2016/2017 freezing season
« Reply #84 on: September 20, 2016, 05:49:24 PM »
I hope some remnants of big block can hold on for a couple more weeks. If they do, then I expect them to seed ice growth in the Beaufort. If that happens, then ice growth should speed up significantly since it will be growing from different fronts.

As we approach nearly ice free conditions, "big blocks" of ice could be pushed to strategic locations around the arctic to seed ice growth. This should give the freezing season a head start, maximizing ice production in the freezing season. The more ice produced in the freezing season, the more "negative heat" we can store for summer.
So, these are attractors at the edge of chaos to use the popular parlance.

DoomInTheUK

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Re: The 2016/2017 freezing season
« Reply #85 on: September 20, 2016, 05:55:13 PM »
I hope some remnants of big block can hold on for a couple more weeks. If they do, then I expect them to seed ice growth in the Beaufort. ......

Sadly not. I suspect it will remain, but the ice can only have an influence within a very small distance of itself, maybe as little as a few tens of feet. The ice will come, but the sea is not a supercooled fluid, no seeding to force nucleation here.

solartim27

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Re: The 2016/2017 freezing season
« Reply #86 on: September 20, 2016, 06:05:33 PM »
Sorry, couldn't resist ( though I imagine everyone here has seen it ):
https://www.youtube.com/watch?v=OqVyRa1iuMc
FNORD

oren

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Re: The 2016/2017 freezing season
« Reply #87 on: September 20, 2016, 06:05:33 PM »
OTOH, the surface where Big Block melted off is possibly fresher and colder than other areas in the Beaufort, so refreeze could begin earlier and/or be faster at that area.

Archimid

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Re: The 2016/2017 freezing season
« Reply #88 on: September 20, 2016, 06:30:58 PM »

 I suspect it will remain, but the ice can only have an influence within a very small distance of itself, maybe as little as a few tens of feet.

The floe is an area with lower temperature, lower albedo, no waves and lower salinity than the surrounding ocean.  If all other things are the same, the water very close to the floe will freeze before the water farther away. This makes the floe larger. A larger floe influences even more area. Rinse and repeat while the conditions are conductive for freezing.

This can already be seen in the beginning of the freezing season. The first part to freeze was the low concentration area close to the pole. In that area  ice grew in all directions. On the other hand, the wrangle arm solidified first (ice growth in all directions from the outside in), and is now growing from the inside out.

 I still have hopes for Big Block. Even if it was only half a kilometer of ice, it might show the behavior I describe. If it does, then we have a way to seed ice. Of course that can only be done if we indeed get a "nearly ice free" arctic before we get a literally ice free arctic. If we do, then the ice in the nearly ice free arctic can be moved around to maximize winter ice production. The more ice at the beginning of the melting season the better.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #89 on: September 20, 2016, 09:26:50 PM »

 I suspect it will remain, but the ice can only have an influence within a very small distance of itself, maybe as little as a few tens of feet.

The floe is an area with lower temperature, lower albedo, no waves and lower salinity than the surrounding ocean.  If all other things are the same, the water very close to the floe will freeze before the water farther away. This makes the floe larger. A larger floe influences even more area. Rinse and repeat while the conditions are conductive for freezing.

This can already be seen in the beginning of the freezing season. The first part to freeze was the low concentration area close to the pole. In that area  ice grew in all directions. On the other hand, the wrangle arm solidified first (ice growth in all directions from the outside in), and is now growing from the inside out.

 I still have hopes for Big Block. Even if it was only half a kilometer of ice, it might show the behavior I describe. If it does, then we have a way to seed ice. Of course that can only be done if we indeed get a "nearly ice free" arctic before we get a literally ice free arctic. If we do, then the ice in the nearly ice free arctic can be moved around to maximize winter ice production. The more ice at the beginning of the melting season the better.

Where there is ice, there is less heat to be released and therefore there is greater probability of freezing around, especially if water around the remains is colder and fresher. I don't see it as seeding, simply as a sink of heat relative to the surrounding area because it is colder and solid to start with.
The problem is that the effect won't go very far or very fast unless it is a big extension, because the energy anomaly is finite. How big to be felt by the satellites before refreezing is generalized? No idea.
« Last Edit: September 20, 2016, 09:43:28 PM by seaicesailor »

Jim Hunt

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Re: The 2016/2017 freezing season
« Reply #90 on: September 20, 2016, 09:59:25 PM »
Should anyone wish to join me in registering an official complaint with the BBC about coverage of Arctic sea ice on yesterday's Today programme a link to the requisite online form and my own humble effort can be seen at:

http://GreatWhiteCon.info/2016/09/radio-four-in-arctic-sea-ice-bias-shock-today/#Sep-20

To summarise, either Matt Ridley has no idea what he’s talking about or he has an agenda. In either case reporting his views without adequate “balancing” comment badly lets down BBC Radio 4 listeners. How do you intend to remedy this?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Archimid

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Re: The 2016/2017 freezing season
« Reply #91 on: September 20, 2016, 10:43:09 PM »
Sorry, couldn't resist ( though I imagine everyone here has seen it ):
https://www.youtube.com/watch?v=OqVyRa1iuMc
Thanks I've never seen it before. Fun and insightful stuff.
I am an energy reservoir seemingly intent on lowering entropy for self preservation.

A-Team

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Re: The 2016/2017 freezing season
« Reply #92 on: September 20, 2016, 11:10:56 PM »
Here is an approximate quantitative analysis of the Big Block remnant seen by Yuha on 250 m resolution Terra visible and infrared 3-6-7. It's a bit too small for AMSR2 on most recent days even though it seems to be just within range.

The area of the perimeter of the main block is the same as that of the bottom for 2 m thick ice. The perimeter may have far less of a meltwater skin than the bottom however as water passes by. Recall it is the relative motion of the floe with respect to a stationary open water coordinate system that matters (beyond the basics), ie what wind is doing to the floe in opposition to surface current.

Recall the Beaufort Gyre broke down completely in mid-summer after a couple of pauses and local gyre formation. The 140 day animation from May 1st to Sept 18th is a sight to see; the file size is a little problematic for the forum but something might work out there (for tomorrow).

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #93 on: September 20, 2016, 11:30:39 PM »
Here is an approximate quantitative analysis of the Big Block remnant seen by Yuha on 250 m resolution Terra visible and infrared 3-6-7. It's a bit too small for AMSR2 on most recent days even though it seems to be just within range.

The area of the perimeter of the main block is the same as that of the bottom for 2 m thick ice. The perimeter may have far less of a meltwater skin than the bottom however as water passes by. Recall it is the relative motion of the floe with respect to a stationary open water coordinate system that matters (beyond the basics), ie what wind is doing to the floe in opposition to surface current.

Recall the Beaufort Gyre broke down completely in mid-summer after a couple of pauses and local gyre formation. The 140 day animation from May 1st to Sept 18th is a sight to see; the file size is a little problematic for the forum but something might work out there (for tomorrow).
Anxiously waiting for that :-)
I wonder if that is still a single floe.
The forecasts show no sight of calm weather for many days in Beaufort.
Nice south winds over the area right now
« Last Edit: September 21, 2016, 12:05:42 AM by seaicesailor »

DoomInTheUK

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Re: The 2016/2017 freezing season
« Reply #94 on: September 21, 2016, 10:30:31 AM »

The floe is an area with lower temperature, lower albedo, no waves and lower salinity than the surrounding ocean.  If all other things are the same, the water very close to the floe will freeze before the water farther away. This makes the floe larger. A larger floe influences even more area. Rinse and repeat while the conditions are conductive for freezing.

......

The lower salinity came from melting ice, so yes initially it will freeze up easier. This effect is limited though as freezing seawater increases salinity, and there is little melt water to replenish the fresher water - some bottom melt might still be occurring. The new ice is thin and has marginal effects on wave action.
This floe will cause very little 'extra' ice to form in the Beaufort. Cold air and darkness will do the rest.

A-Team

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Re: The 2016/2017 freezing season
« Reply #95 on: September 21, 2016, 01:14:12 PM »
Here is the Beaufort from the 1st of May to the 18th of September (according to AMSR2 3.1k UHH). An earlier post showed the situation from January 1st to mid-July at five day intervals. It retains the original sea ice concentration color key which is critical to analysis. To show at 700 pixel width would quadruple file size to 22MB, not workable for the forum but an option after downloading (set mode to RGB and interpolation to 'none').

Note local eddies and lack of any effective Gyre from mid-season on. Import of ice from the CAA largely ceased as did export from Beaufort to Chukchi, contrary to textbook bromides.

In discussing the Beaufort Gyre, there's a potential for confusion between motion of floes and motion of surface water that has gotten worse in recent years. When floes are sparse, the effect of wind is much more pronounced and little is learned about surface currents.

Wind induced motion cannot really be predicted from reanalysis because it depends on floe freeboard lip, surface roughness and hydrodynamic drag.

Floe tracking is not essential to ocean current detection: "OSCAR global ocean surface mixed layer velocities are calculated from satellite-sensed sea surface height gradients, ocean vector winds, and sea surface temperature fields using geostrophy, Ekman, and thermal wind dynamics... modeling of the momentum transfer both within and across the boundaries of the turbulent mixed layer. http://www.esr.org/oscar_index.html"

This is available at nullschool along with wind power density but it would be difficult to partition floe motion between the two with oscar not specialized to the Arctic Ocean, only recalculated at five day intervals, and limited to ice free areas.

Our interest is more in transport of recalcitrant ice to regions more favorable to melt. From the animation frames, it would be feasible to estimate how much thick multi-year ice moved from the CAB to melt in the Beaufort, as part of a larger project that considered export to the CAA, Nares, Fram and Barents front. Matching seasonal time series (animations) of these regions can be carved out of the same 141 MB master file (tomorrow).

These latter process export melt thermodynamics along with the ice. This year seemed quite odd, but perhaps it was just weather rather than the new normal.

Below the animation, there's an idealized average view of annual ice drift vectors from Woods Hole. There is also a mooring (to the sea floor) in the Beaufort that does not move with the ice.
« Last Edit: September 21, 2016, 01:28:50 PM by A-Team »

FishOutofWater

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Re: The 2016/2017 freezing season
« Reply #96 on: September 21, 2016, 07:22:37 PM »
The loop of ice movement shows a cyclonic flow of ice towards Barrow canyon that the buoy map does not pick up. That map also isn't showing much flow through the CAA.

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #97 on: September 21, 2016, 11:49:04 PM »
Nice!! Thank you A-Team.
Trying to understand these jet-like currents and the mostly clockwise rotating eddies (except near Barrow where the two main jets collide, and as FOOW points out; the rotation is anticlockwise.
Curiously the HYCOM simulations showed eddies mostly with the wrong cyclonic spin, as seen  back in June-July.
http://forum.arctic-sea-ice.net/index.php/topic,1493.msg82109.html#msg82109
http://forum.arctic-sea-ice.net/index.php/topic,1493.msg84743.html#msg84743

Going thru this paper, very difficult to read, but deals with much of these eddies we have seen in the Beaufort sea this summer:
https://goo.gl/a7J5Na

Note how one of the companions of BB gets caught in the jet around mid July, and is drifted away well into the Chukchi sea.
There are batches of export of ice from CAB to Beaufort IMHO, due to the storms dispersing the ice, not as strong as that from the initial Gyre in April, but they are there and the ice melts quickly.
And the final vacuum of ice reaching the Wrangel arm, may be caused by that jet from Beaufort to Chukchi rather than, or not only by, Chukchi current or simple direct albedo amplification.
The melting power was amazing, this was really good MYI. Fascinating stuff.
« Last Edit: September 22, 2016, 12:19:06 AM by seaicesailor »

seaicesailor

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Re: The 2016/2017 freezing season
« Reply #98 on: September 22, 2016, 03:19:58 PM »
Compaction remains almost as low as early this month, very diffuse edges yet.

https://forum.arctic-sea-ice.net/index.php/topic,382.0.html

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Re: The 2016/2017 freezing season
« Reply #99 on: September 23, 2016, 12:44:47 PM »
Perhaps I'll have to cross post this elsewhere! It's far more obvious on AMSR2, but as we know AMSR2 doesn't report every last little bit of sea ice.

According to the Canadian Ice Service it is (or was on the 19th at least) possible to circumnavigate Banks Island in a small yacht:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein