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uniquorn

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Re: The Nares Strait thread
« Reply #1350 on: December 11, 2018, 11:31:06 PM »
So the big floe looks like it popped out like a cork over the last 3 days.
Worldview, viirs bt15n, dec5-10
Polarview dec11

Brigantine

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Re: The Nares Strait thread
« Reply #1351 on: January 04, 2019, 12:32:01 AM »
I thought I remembered a formation equivalent list, but I can't find it. Just that it is normally in "January/February".

[...] approx. breakup times, southern "arch" in Kane Basin unless noted otherwise:
[...] I should note - as can be inferred from the numbers - that the dates are somewhat rounded:

2007 - No arches formed.
2008 - June 10th(?)
2009 - No southern arch. Northern arch broke around June 30th.
2010 - July 10th
2011 - July 5th.
2012 - June 30th.
2013 - July 10th.
2014 - June 20th.
2015 - July 5th.
2016 - June 30th
2017 - No southern arch. Northern arch broke around May 10th.
2018 - June 30th.

oren

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Re: The Nares Strait thread
« Reply #1352 on: January 04, 2019, 05:18:06 AM »
I thought I remembered a formation equivalent list, but I can't find it. Just that it is normally in "January/February".

[...] approx. breakup times, southern "arch" in Kane Basin unless noted otherwise:
[...] I should note - as can be inferred from the numbers - that the dates are somewhat rounded:

2007 - No arches formed.
2008 - June 10th(?)
2009 - No southern arch. Northern arch broke around June 30th.
2010 - July 10th
2011 - July 5th.
2012 - June 30th.
2013 - July 10th.
2014 - June 20th.
2015 - July 5th.
2016 - June 30th
2017 - No southern arch. Northern arch broke around May 10th.
2018 - June 30th.
I will try to come up with such a database. It's more complicated as visual WorldView is not available during the dark months.

Jim Hunt

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Re: The Nares Strait thread
« Reply #1353 on: January 04, 2019, 02:21:37 PM »
It's more complicated as visual WorldView is not available during the dark months.

However: https://go.nasa.gov/2Tqp973
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

oren

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Re: The Nares Strait thread
« Reply #1354 on: January 04, 2019, 02:34:30 PM »
Thank you Jim!

Espen

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Re: The Nares Strait thread
« Reply #1355 on: January 04, 2019, 03:28:00 PM »
Or Sentinel 1:
Have a ice day!

oren

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Re: The Nares Strait thread
« Reply #1356 on: January 04, 2019, 04:47:02 PM »
Espen thanks, I actually prefer Sentinel. But is there a link that can provide a direct animation of Sentinel, in the style of Worldview? I usually access Sentinel images via the DMI web site, and while quite useful for short term work it's very tedious when comparing tens or hundreds of images.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #1357 on: January 04, 2019, 08:57:52 PM »
Oren,
I think the answer is "No," but my computer has a program - Snagit - that can be used for a few screens.  I click from screen to screen about a second per frame.  The resulting MP4 shows floes are still moving [below - I wish I could make the image smaller...].  I can save the separate images within the MP4 as PNGs with exact same boundaries.

The far end from rocket science.  At work I'm limited to software they give me, and at home I'm a cheapskate.
Arctic ice is healthy for children and other living things.

Espen

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Re: The Nares Strait thread
« Reply #1358 on: January 04, 2019, 11:06:55 PM »
The far end from rocket science.  At work I'm limited to software they give me, and at home I'm a cheapskate.

Tor,
When handling the Sentinel image data, in this case the initial image a .TIF is >GB, you need a good editor to handle images this size, I use Photoshop CC 2017 (too lazy to download the new version) but it is far from the cheapest available, but the GIF animators are usually for free and very easy to use.
Have a ice day!

uniquorn

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Re: The Nares Strait thread
« Reply #1359 on: January 06, 2019, 08:39:35 PM »
New fractures. edit: Worldview,viirs,bt15,night,jan6-7  https://go.nasa.gov/2FcfPR7
« Last Edit: January 07, 2019, 10:38:23 AM by uniquorn »

uniquorn

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Re: The Nares Strait thread
« Reply #1360 on: January 11, 2019, 11:55:25 AM »
Looking a bit weak beyond the next arch.
Worldview,viirs,bt15,night,jan9-11

Adam Ash

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Re: The Nares Strait thread
« Reply #1361 on: January 17, 2019, 10:39:33 AM »
Holy Moly Batman!  Is that Nares Straight running like a tap in mid-winter???

oren

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Re: The Nares Strait thread
« Reply #1362 on: January 17, 2019, 10:47:16 AM »
It usually does until end-Jan or early Feb, so nothing out of the ordinary. But it's me to blame, as I haven't got around to summarizing the dates from past winters.

Niall Dollard

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Re: The Nares Strait thread
« Reply #1363 on: January 17, 2019, 09:37:29 PM »
I'll try to give you a hand Oren.  :)

Using primarily the sentinel images of the Kane Basin available on

 http://ocean.dmi.dk/arctic/kane.uk.php

And also scrolling back through this thread, I make it the following dates for the start of southern arch formation. The start date being the first date on which there are no more break aways.

2018 - March 1st
2017 - No southern arch
2016 - December 6th (2015)

Dec 6th  does seem very early. But I've had a crosscheck on the arch profile and several months later it is still the same as it was on Dec 6th.

What did we agree on before ? That for an arch to qualify, it must hold for three days minimum ? ie if it forms on 1st March it must still be holding perfectly on 4th March ?

oren

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Re: The Nares Strait thread
« Reply #1364 on: January 18, 2019, 02:02:55 AM »
Thank you Niall !
In my opinion an arch is an arch if it holds for the rest of the winter, give or take a few bits and pieces. So if it breaks and flow continues a week later, it's disqualified.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #1365 on: January 18, 2019, 02:23:11 AM »
I believe "holding for three days" was my invention associated with a poll I started, created out of whole cloth (if not also useful for defining a (money-less) 'wager').  I had a 7-day threshold for bridges/arches in the Lincoln Sea. Some thought the 3-day threshold too short, although I think the first 3-day set bridge held that year.  (All details are per my memory.)
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uniquorn

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Re: The Nares Strait thread
« Reply #1366 on: January 18, 2019, 02:37:34 PM »
Would this depiction of current be correct?
edit: Thinking about it, denser water would take the deeper channel but some may get forced to the surface in the shallows.
« Last Edit: January 18, 2019, 02:50:42 PM by uniquorn »

uniquorn

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Re: The Nares Strait thread
« Reply #1367 on: January 19, 2019, 05:41:18 PM »
Thought I'd check what Mercator thinks. Here is their model of current at 34m, sep1-jan18.
Will look a bit deeper later.
« Last Edit: January 19, 2019, 06:43:00 PM by uniquorn »

Niall Dollard

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Re: The Nares Strait thread
« Reply #1368 on: January 19, 2019, 07:04:04 PM »
Thank you Niall !
In my opinion an arch is an arch if it holds for the rest of the winter, give or take a few bits and pieces. So if it breaks and flow continues a week later, it's disqualified.

I agree. It should hold at least 1 month.

I think also that, for this summarizing exercise, we only count arches within the Nares Strait and not in the Lincoln Sea.

oren

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Re: The Nares Strait thread
« Reply #1369 on: January 19, 2019, 09:38:30 PM »
Ideally I would like to record the dates of the Kane Basin arch forming, but if none formed then the date of a northern arch in the Lincoln Sea.
Ideally I would find the mental fortitude to go through the exercise... but recently too much work has taken its toll.

Niall Dollard

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Re: The Nares Strait thread
« Reply #1370 on: January 19, 2019, 10:10:43 PM »
Just added 2015 .

2018 - March 1st
2017 - No southern arch
2016 - December 6th (2015)
2015 - February 13th


uniquorn

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Re: The Nares Strait thread
« Reply #1371 on: January 21, 2019, 07:09:11 PM »
Lincoln Sea fractures consolidated further today. https://go.nasa.gov/2FGH0nn
A bit close to volume limit at the moment so using Mercator 92m salinity as an indication of current, nov1-jan19
« Last Edit: January 21, 2019, 07:19:35 PM by uniquorn »

Niall Dollard

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Re: The Nares Strait thread
« Reply #1372 on: January 23, 2019, 12:58:45 AM »
I've had more time to look over various satellite images and here is what I have found for start dates. They really are very variable.

The standout year was 2012/2013. After the record low ice year. The Petermann ice island had lodged in the Nares Strait and as early as Nov 11th the southern arch was beginning to form.

 https://icyseas.org/2012/11/13/nares-strait-ice-arches-and-petermann-ice-island-2012/

2018 - March 1st
2017 - No southern arch
2016 - December 6th (2015)
2015 - February 13th
2014 - January 5th (northern arch started - southern just after)
2013 - November 8th (2012)
2012 - December 6th (2011)
2011 - January 29th

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1373 on: January 24, 2019, 01:33:18 PM »
Not 100% sure, but from today's picture, it looks like the amount of debris in the strait has reduced.

Link >> http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201901240758.NOAA.jpg

Would that mean the current has become stronger?

And another question: The cracks along the coastline are they due to pressure from above? And if so is it due to wind or another current?

uniquorn

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Re: The Nares Strait thread
« Reply #1374 on: January 24, 2019, 02:58:55 PM »
The floes are still making their way down the strait, see https://go.nasa.gov/2UbWItX for better resolution.
Cracks along the northern coastline are nearly always there due to the ice movement, normally on it's way to the Fram.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1375 on: January 24, 2019, 03:38:01 PM »
Thanks Unicorn,

i take it the movement is mostly driven by wind then?

uniquorn

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Re: The Nares Strait thread
« Reply #1376 on: January 24, 2019, 05:42:54 PM »
A bit off topic, but perhaps relevant to Lincoln/Nares at the moment.
A basic map of Arctic ocean currents, though it is more complex at different depths when looking in more detail.
edit: not sure I even agree with that since it appears to have the Beaufort gyre going anticlockwise.
edit2: This one looks better from Robert Newton, Columbia university
edit3: Prefer this from Rebecca Woodgate for atlantic circulation
« Last Edit: January 27, 2019, 08:11:36 PM by uniquorn »

uniquorn

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Re: The Nares Strait thread
« Reply #1377 on: January 25, 2019, 10:33:16 PM »
worldview jan21-25

Niall Dollard

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Re: The Nares Strait thread
« Reply #1378 on: January 26, 2019, 02:08:07 PM »
Big Chunk heading into the Robeson and Kennedy Channels.

Images are from 24th and 25th Jan.


Shared Humanity

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Re: The Nares Strait thread
« Reply #1379 on: January 26, 2019, 04:16:35 PM »
In years past, when a floe that size entered the Nares, we would discuss as to whether we thought it might hang up on Hans or Franklin Islands and contribute to the closing of the strait for the season.

I am afraid that today's big flows from the Lincoln Sea are not at all like the thick rafts of MYI we use to see entering the Nares. These are fragmented MYI, knitted together with this years, very young ice. You can be certain it will shatter into tiny fragments as soon as it hits any obstacle.

oren

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Re: The Nares Strait thread
« Reply #1380 on: January 26, 2019, 05:45:04 PM »
 Very true.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #1381 on: January 26, 2019, 08:16:48 PM »
Quote
we would discuss as to whether we thought it might hang up on Hans or Franklin Islands
Ah, but it was so much fun speculating!  But even the Petermann Ice Island (2012)
didn't get suck in Nares Strait.  A floe named 'shark', reported in 2015, "got stuck for a day or so, but then shattered."
« Last Edit: January 28, 2019, 02:32:35 AM by Tor Bejnar »
Arctic ice is healthy for children and other living things.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1382 on: January 27, 2019, 07:27:42 PM »
24.Dec.13

No one ever mentioned Santa.

uniquorn

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Re: The Nares Strait thread
« Reply #1383 on: January 27, 2019, 08:16:42 PM »
More related fractures appearing further north in the Lincoln sea, jan26-27
Worldview, viirsbt15, green and rainbow

Comparison with feb3 2018
« Last Edit: January 27, 2019, 11:39:17 PM by uniquorn »

uniquorn

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Re: The Nares Strait thread
« Reply #1384 on: January 29, 2019, 02:26:35 PM »
Bit the bullet and went back to november to look at surface current. Too cloudy before that.

oren

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Re: The Nares Strait thread
« Reply #1385 on: January 29, 2019, 03:11:32 PM »
Great animation. It does seem as if the current comes from the north or northeast, rather than from the east along the Greenland coast.
Also as I recall from summer watching, large floes directly to the north of Greenland sometimes go left, sometimes go right, and often linger in place, so I doubt there's much of a surface current there.

Niall Dollard

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Re: The Nares Strait thread
« Reply #1386 on: February 01, 2019, 12:12:15 AM »
Half of "Big Chunk" that headed into the Robeson Channel on 24th Jan has got stuck. Will it hold for long ?

It may be assisted by the much bigger one now entering the Robeson Channel.

Phil.

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Re: The Nares Strait thread
« Reply #1387 on: February 01, 2019, 12:18:44 AM »
Half of "Big Chunk" that headed into the Robeson Channel on 24th Jan has got stuck. Will it hold for long ?

It may be assisted by the much bigger one now entering the Robeson Channel.

Or get knocked out by it?

Niall Dollard

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Re: The Nares Strait thread
« Reply #1388 on: February 01, 2019, 01:00:15 AM »
Half of "Big Chunk" that headed into the Robeson Channel on 24th Jan has got stuck. Will it hold for long ?

It may be assisted by the much bigger one now entering the Robeson Channel.

Or get knocked out by it?

Maybe. The pressure will come on.

The GIf reminds me of that childhood trick that's done with separating/moving half your index finger and thumb.  :D

uniquorn

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Re: The Nares Strait thread
« Reply #1389 on: February 01, 2019, 09:06:43 PM »
A small rebound behind the stuck floe. It's not looking too good for my bet (but maybe better for the ice)

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1390 on: February 02, 2019, 05:56:00 AM »
I noticed a slowdown. Now the rebound. This is quite exciting actually!

We can't assume the 'big chunk' is way bigger underwater than we see in the sat pics and is therefore stuck, or can we?

Would that mean the current has changed directions?

oren

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Re: The Nares Strait thread
« Reply #1391 on: February 02, 2019, 08:47:06 AM »
In all probability the wind has changed direction. The current is rather constant I think.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1392 on: February 02, 2019, 10:08:04 AM »
Hey Oren,

according to earth.nullschool.net, you are right. The wind has blown in this direction the last couple of days, though only very slowly (~5-20 km/h).

In my layman's understanding a current should put way more force onto that chunk then the wind possibly could at such low speeds.

Or maybe the current is still there, only not at the surface atm due to the wind and/or turbulence in the strait.

uniquorn

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Re: The Nares Strait thread
« Reply #1393 on: February 02, 2019, 01:50:19 PM »
Rebound suggests the stuck floe has depth and has slowed shallow current into the Nares. Maybe some back pressure but probably wind causing the rebound. The image above was a lucky catch as worldview has since replaced it with a slightly clearer view and it does indeed just look like slowdown.
Enhancement doesn't offer too much more information though brightness temperature suggests the floe is thicker in places. The weaker sides that might have fractured are being compressed, the eastern side looking weakest. Some surface current is visible down stream on both sides, more on the west, probably refreezing meltwater. A bit odd as I think the strait is shallower on the west. Probably a healthy current at depth as floes downstream are moving quite rapidly.
Meanwhile upstream the ice is thickening, hopefully :)

edit: unless it's thinned overnight on the western side. In which case I may still be in with a chance....
« Last Edit: February 02, 2019, 02:16:03 PM by uniquorn »

uniquorn

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Re: The Nares Strait thread
« Reply #1394 on: February 02, 2019, 08:16:33 PM »
Suomi NPP viirs makes 2 passes over the arctic. This one is from the 'day' pass, a few hours later. Little chunk scrapes forward while its other half shatters and big chunk commits to the strait.
Worldview viirs,day feb1-2
A closer view from polarview yesterday on jan31
« Last Edit: February 02, 2019, 08:45:59 PM by uniquorn »

Niall Dollard

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Re: The Nares Strait thread
« Reply #1395 on: February 02, 2019, 10:11:17 PM »
It looks increasingly like we have a blockage.

oren

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Re: The Nares Strait thread
« Reply #1396 on: February 03, 2019, 12:47:35 AM »
I think it's quite unusual to have a blockage inside the Robeson Channel. OTOH, the date is typical and wind reversal is a key ingredient.
In any case, I'd delay judgement for a few days. But my bet is still  on unblocking.
« Last Edit: February 03, 2019, 06:20:49 PM by oren »

Niall Dollard

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Re: The Nares Strait thread
« Reply #1397 on: February 03, 2019, 05:45:31 PM »
There is some movement again today in the channel. Didn't hold for long.

b_lumenkraft

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Re: The Nares Strait thread
« Reply #1398 on: February 03, 2019, 06:26:46 PM »
27. Jan to 03.Feb.
Brightness Temperature (Band 31-Day) Terra / MODIS

Shared Humanity

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Re: The Nares Strait thread
« Reply #1399 on: February 03, 2019, 08:03:30 PM »
There is some movement again today in the channel. Didn't hold for long.

Popped like a cork and everything behind is on the move. Big block will be fun to watch.