The Nares Strait thread

[magnamentis]

I didn't expect this, looks weird. What happened here (day before yesterday, day 160)?

winds ?

[oren]

Now the flow has been reversed again, and there's been another big breakup on the northwest ( Ellesmere) side. Seems the weak ice of this season due to poor winter came here too. Usually the ice becomes mobile behind the arch, and finally the arch gives way. This year it's the opposite.

[johnm33]

There are weaknesses appearing on the Ellesmere shore

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160613TERR.jpg
they extend up into Kennedy too with some on the Greenland side, I see this as indicating thinning, which as yet is not visible, taking place. The tides are increasing so this will only accelerate, will it hold till the tides turn on 21st I'm inclined to think not, but it depends on how much pent up energy is restrained in Humbolt.

http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/20160613TERR.jpg

[johnm33]

Looking at these two images 2 days apart the ice looks a little bluer Ellesmere side, by the entrance to Kane it's fairly subtle so better seen in the links.

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160612TERR.jpg

http://ocean.dmi.dk/arctic/images/MODIS/Kane/20160614TERR.jpg

[Tealight]

S2A shows a new crack developing from a polyna on the canadian side.

[johnm33]

It could be nothing but open the link and switch between 15/16 from roughly bottom center there's a broad swathe at about 60⁰ getting bluer faster than it's surroundings.
http://go.nasa.gov/1UcY3tA

[oren]

It could be nothing but open the link and switch between 15/16 from roughly bottom center there's a broad swathe at about 60⁰ getting bluer faster than it's surroundings.
http://go.nasa.gov/1UcY3tA

Yes there is. And this whole blue area did not exist a few days ago.
While scrolling I noticed that the bottom-most (Greenland) corner of the arch crumbled and cleared in the past few days, starting from around June 11th.

[Neven]

Yup, things are turning blue. Let's see if the arch makes it to the end of the month (probably not).

[Tor Bejnar]

Oren wrote: "While scrolling I noticed that the bottom-most (Greenland) corner of the arch crumbled and cleared in the past few days, starting from around June 11th." 
About 10 days ago I reported what I believed to be a 'change' in the ice along Greenland's rocky shore in Kane Basin.  The ice-free end of the arch may be a manifestation of what I'd seen.

Neven wrote: "Let's see if the arch makes it to the end of the month (probably not)."  I also expect the Kane Basin ice to break in June.  I have no opinion about the ice in rest of Nares Strait, though.

[Tor Bejnar]

cross post - Thanks philiponfire - post #694 in Arctic Image of the Day:

Floes have been breaking off regularly in Kane basin for the last month and now we can see the beginning of the break up of Nares strait from the north end.

[Tor Bejnar]

Cracks also appear within Nares Strait just 'south' of the Lincoln Sea. (North is, more-or-less, to the right.)

(The unsupported Greenland corner of the ice bridge in Kane Basin broke off.)

[johnm33]

Big tides, ice thinning [turning blue] and cracks up in Kennedy, I don't think it'll hold till the weekend.

[oren]

Cross-posting for future reference.

[Tor Bejnar]

As best I could, these two images cover the same area (June 19 and June 21).  Note the continuing loss of fast ice along the Greenland (lower left) shore, apparently beyond the new leading edge of the ice bridge (aka ice arch) as it had done last week.  Although the bridge end got trimmed (between the two dates), most of the bulge on the Greenland side of the bridge appears to be in exactly the same place in both images.  Other areas along the bridge, however, notably the furthest-to-the-right arch apex and the arch edge next to the largest broken-off floe in the June 19 image, appear to show the bridge slowly collapsing (that is, moving 'left').

[I wish I could do an animation! With two browser tabs, one open to each date on the Rapid Response - LANCE images (links to source images on dates above), I positioned the images so Greenland shores exactly matched when I clicked back and forth.  I captured the posted images that matched areas, as best I could (for left, right and top edges by using browser window references that didn't change between images).]

[johnm33]

Tor "I wish i could do an animation" me too, but with Worldview you just click and hold, all the 'chunks' in the pack are stationary, but it keeps getting bluer. http://go.nasa.gov/28Oc6qE

[Laurent]

If I can do it, you can do it !
Open Worldview, choose the place you want to record then press print screen button on your keyboard.
Do that for each frame.
Go to your directory, right click on the first file, choose open with Gimp (http://www.gimp.org/downloads/)
Be sure you have the "tracing paper" window open (ctrl + L) !
Go to file>open as a calc choose the second, then repeat until you have all the frames.
Crop the part that you want. (use the tool cutter for that)
Go to Image>scale image rescale to 650 pixel in length
Go to File>Export as> choose Gif and rename the file extension as gif.
Ask to use  a time between frames that does suit you (1000 ms).
That's it.
By the way, I don't find the animation particularly interesting.

[oren]

If I can do it, you can do it !
...
By the way, I don't find the animation particularly interesting.

Thanks for the detailed reminder. Did it a few times in the past with Gimp, but it's still mentally complicated.

As to the animation, careful eyeballing shows not just the Greenland corner peeling away, and then the whole section after it slowly disappearing, but also the whole left half of the arch moving slightly but definitely forward in the last couple of frames - which might mean total loss of structural support and the ice becoming mobile at last.
This is what Tor reported, but watching it live made it much easier to see.

[Tor Bejnar]

Thanks, oren, for seeing what I saw and what shows it the Worldview animation.  (For others, carefully place your mouse's pointer exactly on the arch's edge near where the largest ice floe separates (near the apex of the arch), and see that the ice edge moves southward (left) in the last few frames.)

Yes, the animation is 'required' to see the movement.

And thanks, Laurent, for the tutorial.  This old dog might be able to learn this new trick!

[johnm33]

Here we go, maybe

http://go.nasa.gov/290kYdn
Thanks Laurent if the fog ever clears [in my head] I'll learn that.

[oren]

A big one! It seems collapse is underway.
I also notice that suddenly all the ice in Kennedy Channel is fractured into floes.

[Adam Ash]

While the ice bridge has been holding, there has been continual small scale ice movement in action along the coast of Ellesmere Island just north of the bridge...

[Buddy]

A big one! It seems collapse is underway.

Oren....when is the "usual time" for the collapse over the last 5 years or so?  Is it June...July...other?  Thanks....  Buddy

[oren]

A big one! It seems collapse is underway.

Oren....when is the "usual time" for the collapse over the last 5 years or so?  Is it June...July...other?  Thanks....  Buddy

I am hardly the expert on the subject (or any subject on this great forum) but browsing this thread's back pages will give you the answer you seek.
Looking back to 2015 it happened at around July 10th, but the order of things was somewhat reversed - first the ice started breaking up all along the Strait, later the arch started losing bits and pieces, and finally the ice from the north gave it one big push and it started moving and was gone. This year the bits and pieces part came much earlier, the ice breaking up at around the same time. I highly doubt the final part will wait til July 10th, it may have started already (the movement that Tor spotted).

Here's an animation of last year's process.

http://forum.arctic-sea-ice.net/index.php/topic,176.msg56610.html#msg56610

When I have time later I'll browse other years, but feel free to do it yourself  - it's an interesting exercise.

[Jim Hunt]

There's significant movement further north now also:

[Laurent]

.

[Tor Bejnar]

As the last frame of Laurent's gif shows, fissures near the 'north' end of Kane Basin are opening.  (I didn't notice them until I looked at a DMI Satellite Image).

[be cause]

Yes .. it looks like a door is opening for yet more of the multi-year ice to exit the Arctic .

[Tor Bejnar]

Today's Lance MODIS shows new fissures in the northern (Greenland side) of Kane Basin, next to (edit: near) the Humboldt Glacier (attached).  Yesterday's DMI image of the Kane Basin ice bridge suggests to me that 'something' might be missing (that is, a chunk of ice) through the clouds near the Greenland side, but time (a few hours?) will tell.  (Edit after the full-Kane-Basin image below:  no missing ice, just melt ponding.)

[johnm33]

High tide passed at about 20:00utc so maybe the next image will be of collapse, it sure looks primed.

http://go.nasa.gov/28ZdFEy

[Adam Ash]

Love the movement, south, south NORTH!  Not much integrity there..

[johnm33]

Slow collapse continues beneath the clouds

from http://www.polarview.aq/images/106_S1jpgsmall/201606/S1A_EW_GRDM_1SDH_20160627T213037_BF6B_N_1.jpg

[Adam Ash]

There does not seem to be any 'integrity' / glue holding anything in the Straight together does there.  Is if a combination of wind opposed to current that is keeping it in position?  Its going to go like slush down a drain once it gets a sense of direction!

[johnm33]

"does not seem to be any 'integrity'" It looks broken , but if it was it'd be ripping out of there fast. At the moment there are @8ft. tides[2.4m] which usually means enhanced flows from the north, you can just see the internal waves generated by the flow on my last post, that image is about 1/2 hr. after high tide, the tides are at least as important for the amount of melt they generate as they are for movement, the melt, whilst it thins also glues the ice back together. So you get a lot of melt [and compression] further north, but if it's cold enough in the south it refreezes sometimes extending the arch sometimes just binding it. It's a fools errand trying to predict it, I'm looking for a cure.

from http://go.nasa.gov/29ddfsv

[Adam Ash]

Hi John!  I suspect that our 'cure' is a good old dose of 'patients'!  Its all very interesting, in a remote sort of way - a bit like watching gangrene moving up your leg - eventually it will take us out.

[oren]

It's a fools errand trying to predict it, I'm looking for a cure.

You are so right... Still my gut feeling is a few days will see this mess moving. 

[Neven]

I agree, this can't take long. I think it'll break up within days now.

[Tor Bejnar]

It's gotta break soon!  (But I had predicted 'during June', so I lost that bet!)
From: https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016184.terra.250m

[Laurent]

An other view :

[johnm33]

It's breaking apart, big tides, 4m greenland side 2.8m Ellesmere, winds blowing north [nullschool] pushing the ice away in Lincoln, that'll mean warmer water coming from the north. My guess is it'll all be running through by the 6th.

[Tor Bejnar]

From http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20160703T123301_7B7C_N_1.final.jpg
Cracking along the Greenland shore.  No image I have access to shows the crack going to the arch's underside, though.

[JayW]

Edit: I totally jumped the gun, just clouds. 

Sorry for the terrible resolution, but looking at AVHRR images from the Canadians, it appears the Nares may have blown out in the last couple hours.  Edit: it was somewhere between 0743z and 0924z.

http://weather.gc.ca/satellite/satellite_anim_e.html?sat=hrpt&area=dfo&type=nir

[Shared Humanity]

Low resolution or not, thanks for the animation. It is obvious that Kane Basin has collapsed. Not as clear what is going on north of the basin.

[Tor Bejnar]

I presume these cracks go to the bridge's leading ice edge.
image from https://lance.modaps.eosdis.nasa.gov/imagery/subsets/?subset=Arctic_r03c02.2016186.terra.250m

[Tor Bejnar]

The Kane Basin ice bridge is (confirmed) broken.
From http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20160704T212223_46AE_N_1.final.jpg, the Greenland shore is at the bottom of the image and open water is on the left.  70 and 72W lines of longitude show, as does the 79N parallel.

The Canadian side has also broken (2nd image - 72 and 74W lines of longitude show).

The next question I have is:  When will the first piece of (current) Lincoln sea ice flow through the entire strait?

[Adam Ash]

Nares is ready to rumble!

[crandles]

going ..... going .....

Could that big block in the middle stay whole and block the narrow entrance? I would expect that much movement would cause further break ups but it would be an unusual date for an arch formation.

[Tor Bejnar]

...
going ..... going .....
...

I'm not gonna to hold my breath about the ice "going" anywhere! 
It 'wanted' to break up, but it appears it likes where it is.

[johnm33]

"going  going"
That shot was about 17:00 utc not long after a 'low' high tide there was a big tide just before midnight and with winds blowing south odds are it's moving as we wait for updates.

[crandles]

who gets to say "gone"?

[johnm33]

I can't see this stopping now http://go.nasa.gov/29s9xgA