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Author Topic: The Nares Strait thread  (Read 581299 times)

Wipneus

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Re: The Nares Strait thread
« Reply #600 on: March 04, 2015, 08:10:17 AM »
Arch is holding, not a crack visible apart from a bad image stitch.

johnm33

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Re: The Nares Strait thread
« Reply #601 on: March 04, 2015, 10:20:20 AM »
With winds as they are and increasing over the next 24hr both at the south end of Fram and all the way down Baffin there's just a slim chance the full moon low tides will induce some cracks.
ot take a look at the energy of the water emerging from below the ice in the lower reaches of the bay especially the turmoil on the coast south of the entrance to Hudson, courtesy worldview/ march 02
http://map2.vis.earthdata.nasa.gov/imagegen/index.php?TIME=2015061&extent=-1407947.5023126,-4186084.1522005,676916.4976874,-2297828.1522005&epsg=3413&layers=MODIS_Terra_CorrectedReflectance_TrueColor,Coastlines&opacities=1,1&worldfile=false&format=image/jpeg&width=8144&height=7376
« Last Edit: March 04, 2015, 12:59:56 PM by johnm33 »

Wipneus

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Re: The Nares Strait thread
« Reply #602 on: March 04, 2015, 10:44:27 AM »
Someone alerted me (thanks!) by email that the sun has risen over the arch, see MODIS image .



Jim Hunt

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Re: The Nares Strait thread
« Reply #603 on: March 04, 2015, 11:59:50 AM »
I actually prefer to use Worldview, which allows easy comparison with previous years:

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/winter-201415-images/#Nares

Here's 2014, on March 5th and a bit cloudy:

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ghoti

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Re: The Nares Strait thread
« Reply #604 on: March 04, 2015, 06:18:35 PM »
And we are only a few days from Worldview showing the Fram in in daylight! We'll be able to compare the ice flowing out the Fram to the ice stuck behind the Nares arch.

solartim27

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Re: The Nares Strait thread
« Reply #605 on: March 04, 2015, 07:41:38 PM »
We can see Fram on Modis.  Here's 3/4 versus 2/20
http://lance-modis.eosdis.nasa.gov/imagery/subsets/?mosaic=Arctic
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Wipneus

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Re: The Nares Strait thread
« Reply #606 on: March 06, 2015, 06:33:43 AM »
Arch looks like it is getting stronger.

(click to animate)

Wipneus

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Re: The Nares Strait thread
« Reply #607 on: March 07, 2015, 08:46:45 AM »
At the top the ice has not realized that the way is blocked.

Wipneus

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Re: The Nares Strait thread
« Reply #608 on: March 09, 2015, 11:50:40 AM »
Sonia's ice floe/berg stuck in the middle of the Kane Basin as seen by Landsat 8 on March 7. The shadows are about 4 pixels or,  @ 15m/pixel, 60m long. With sun elevation of only 5.17o I estimate the height of the central portion a bit over 5 m. So I guess it is not an ice berg after all.

(image resampled at 7.5m/pix)   

Wipneus

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Re: The Nares Strait thread
« Reply #609 on: March 09, 2015, 11:57:18 AM »
The Kane is speckled with objects like these. Here the shadows are about four times as long. In my opinion these are ice bergs.

(image scaled as above)

Sonia

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Re: The Nares Strait thread
« Reply #610 on: March 09, 2015, 12:09:10 PM »
That's my conclusion too from looking at recent MODIS images.  The objects with long shadows are concentrated at the Humbolt and extend out from there in long filaments.  I think a contrast stretch would show this well but I don't have time to mess with it at the moment.

LRC1962

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Re: The Nares Strait thread
« Reply #611 on: March 11, 2015, 01:25:25 PM »
According to this the storm on the south east corner of Greenland seems to pulling wind through the strait. Is it strong enough to make an impact on the blockage?
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viddaloo

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Re: The Nares Strait thread
« Reply #612 on: March 21, 2015, 04:46:34 PM »
What happened to this thread?!

Very high winds in the Nares right now:

[]

johnm33

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Re: The Nares Strait thread
« Reply #613 on: March 21, 2015, 06:28:08 PM »
"What happened to this thread?!"
 It's frozen, even the exceptional tides following the eclipse are unlikely to shift the compressed ice thats rammed into the strait and consolidated these last 5[?] weeks. but you never know...

Wipneus

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Re: The Nares Strait thread
« Reply #614 on: April 19, 2015, 09:32:32 AM »
Some movement in the Lincoln Sea.

Neven

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Re: The Nares Strait thread
« Reply #615 on: April 19, 2015, 10:39:21 AM »
OMG, is Nares opening up on the other side this year?  ;) ;D
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #616 on: April 19, 2015, 02:40:38 PM »
That ice wants out, and if Nares refuses to open up, by gosh, it'll find another way :D
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crandles

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Re: The Nares Strait thread
« Reply #617 on: April 20, 2015, 11:26:56 PM »
question mark arch broken?


Neven

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Re: The Nares Strait thread
« Reply #618 on: April 21, 2015, 12:06:16 AM »
question mark arch broken?

The question mark, yes, but the arch looks pretty solid now. At least, to me. Well spotted, BTW.
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Wipneus

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Re: The Nares Strait thread
« Reply #619 on: April 21, 2015, 08:14:11 AM »
More ice decides not wait for the Strait to re-open.

johnm33

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Re: The Nares Strait thread
« Reply #620 on: April 21, 2015, 11:09:31 AM »
At some point it had to fill, the ice has been compressed into it for 7? weeks, but still the torrent beneath drives through.
 
 from DMI
Looking at the area of Crandles image on worldview, for the last 3 weeks, both Lancaster and Jones have only fresh ice, and as soon as the temps. rise will clear rapidly

crandles

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Re: The Nares Strait thread
« Reply #621 on: April 22, 2015, 09:04:37 PM »
Despite

on 20th


on 22nd

So looks like I was wrong. Question mark still in place. So pieces breaking off south of question mark.

solartim27

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Re: The Nares Strait thread
« Reply #622 on: May 07, 2015, 07:51:52 AM »
Still holding strong, some wind coming through Saturday, might be time to move.
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Tor Bejnar

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Re: The Nares Strait thread
« Reply #623 on: May 17, 2015, 02:32:29 AM »
I don't expect it will come to pass in May, by the US Navy's CICE ice concentration maps forecast less than 100% ice in Nares Strait this next week (down to 30%!). (DMI's Sentinel 1 or MODIS images don't suggest anything to me.)

It think this is just to get us excited!  You know, throw the dogs some bones, and they'll be happy for hours.

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Tor Bejnar

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Re: The Nares Strait thread
« Reply #624 on: May 22, 2015, 04:32:00 PM »
The little polynya at the NE end of Kane Basin (Cape Jackson) is opening up, per TERRA and AQUA images on the DMI website.  The ice bridge should break within ... 2 months.   :P
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Siffy

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Re: The Nares Strait thread
« Reply #625 on: May 24, 2015, 08:43:51 PM »
Another little chunk has broken off in the strait.


Jim Hunt

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Re: The Nares Strait thread
« Reply #626 on: May 24, 2015, 09:02:34 PM »
Whilst this is how the northern end looks at present:
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Sonia

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Re: The Nares Strait thread
« Reply #627 on: May 25, 2015, 12:14:06 AM »
It's fascinating to me that ice in a large part of the Lincoln Sea has stayed mobile all winter.  It would refreeze for a little bit, then winds would change and the polynyas would open right back up.  The ice is all raring to go as soon as the Nares opens.

epiphyte

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Re: The Nares Strait thread
« Reply #628 on: May 25, 2015, 05:00:14 AM »
@siffy - looking at it from this perspective, the chunk that just broke off seems to be losing coherence and starting to melt almost immediately - as though it was insubstantial even before it separated from the arch. If the rest of it is as diaphanous as that part appears to have been, I'd hazard it won't last very long.

solartim27

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Re: The Nares Strait thread
« Reply #629 on: May 25, 2015, 06:59:52 AM »
Here's the Sentinel shot from Polarview, seeing some motion on the bottom of the question mark.  Could open up pretty quick.  Click to animate.
http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150524T121703_5638_N_1.jpg
« Last Edit: May 25, 2015, 07:08:43 AM by solartim27 »
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solartim27

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Re: The Nares Strait thread
« Reply #630 on: May 26, 2015, 06:19:28 AM »
Looks like some strongish winds have stripped some small bits off the bottom of the curve.  I see no other motion flipping between images.
http://ocean.dmi.dk/arctic/image_container.php
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solartim27

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Re: The Nares Strait thread
« Reply #631 on: June 05, 2015, 08:13:55 PM »
Some more slight movement at the Greenland side of the arch in Kane
http://www.polarview.aq/images/106_S1jpgsmall/S1A_EW_GRDM_1SDH_20150605T121704_D869_N_1.jpg
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Sonia

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Re: The Nares Strait thread
« Reply #632 on: June 08, 2015, 01:18:48 AM »
Hans Island weather station reading above freezing for the first time this year I think.

Wipneus

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Re: The Nares Strait thread
« Reply #633 on: June 08, 2015, 08:19:30 AM »
The ice in the Lincoln Bay is stirring again.

solartim27

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Re: The Nares Strait thread
« Reply #634 on: June 10, 2015, 06:10:00 PM »
Strong winds from the south, are those waves in the bay?
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johnm33

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Re: The Nares Strait thread
« Reply #635 on: June 10, 2015, 07:08:03 PM »
It's getting quite warm, for the time of year,


so maybe some movement as the new moon approaches.

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Re: The Nares Strait thread
« Reply #636 on: June 11, 2015, 02:09:45 PM »
Strong winds from the south, are those waves in the bay?

Unless they are interference I doubt they're waves. That wavelength is greater than 50m, and the pattern isn't diffractive.

I suspect they're more likely to be clouds or similar,   
Open other end.

Neven

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Re: The Nares Strait thread
« Reply #637 on: June 11, 2015, 02:30:11 PM »
The day we're able to see waves on satellite images, we need to make for the hills. Make that mountains.  ;)
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nukefix

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Re: The Nares Strait thread
« Reply #638 on: June 11, 2015, 02:45:54 PM »
Strong winds from the south, are those waves in the bay?
They look more like atmospheric rolls that modulate the small-scale roughness of the sea surface.

solartim27

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Re: The Nares Strait thread
« Reply #639 on: June 13, 2015, 07:55:27 AM »
Breakout, must have ben the high surf
« Last Edit: June 13, 2015, 08:04:12 AM by solartim27 »
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solartim27

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Re: The Nares Strait thread
« Reply #640 on: June 13, 2015, 08:39:55 PM »
Jun 13 vs Jun 11
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johnm33

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Re: The Nares Strait thread
« Reply #641 on: June 16, 2015, 11:28:14 PM »
In the last 2 posts by solartim27 there's been a schism across the bay http://www.polarview.aq/arctic which has melted away, we have winds at 40k plus http://earth.nullschool.net/#current/wind/surface/level/overlay=temp/orthographic=0.39,78.15,512 blowing south a new moon what are the chances of breakout at low tide?

werther

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Re: The Nares Strait thread
« Reply #642 on: June 16, 2015, 11:47:24 PM »
Break-out? I'd say good chance. Fracturing is now visible on MODIS across the Strait between Kane Basin and the peterman-Fjord.

johnm33

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Re: The Nares Strait thread
« Reply #643 on: June 17, 2015, 11:24:34 AM »
Courtesy of DMI

A-Team

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Re: The Nares Strait thread
« Reply #644 on: June 17, 2015, 02:44:25 PM »
When the region of interest is white-on-white (as with these Modis images), the contrast can sometimes be usefully expanded to make fuller use of monitor dynamic range. This is especially suited to fractures.

One fast way to do this is mask out the rocks, normalize the remaining contrast to 0,255, and then equalize the (global) histogram. This would take about 15 seconds of twiddling in Gimp or similar.

A better way of bringing out features is to do this locally. For that, look for a menu command called CLAHE in your image processing software. A round-trip to ImageJ2 (free, platform-independent) takes around 45 seconds on this size image.

This time of year, Landsat provides very nice coverage of Nares (via http://earthexplorer.usgs.gov/). The LandsatLook natural color is a small fast file with quite good resolution; the region of the two islands is shown in the snippet below from LC80292482015167LGN00. Much of Nares lies within this single image.
« Last Edit: June 17, 2015, 03:02:14 PM by A-Team »

johnm33

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Re: The Nares Strait thread
« Reply #645 on: June 17, 2015, 09:12:03 PM »
Seemed kind of rude not to give it a shot

some way to go yet

johnm33

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Re: The Nares Strait thread
« Reply #646 on: June 19, 2015, 07:08:08 PM »
Cracks nearing the arch, from DMI

solartim27

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Re: The Nares Strait thread
« Reply #647 on: June 19, 2015, 07:22:34 PM »
How can this not have collapsed yet?!?!  Oh, I get it, this year it's going to break up going to the north with the wind.  Here's the Worldview pic, you can identify the individual bergy bits seen in Sentinel now, so there must be no more snow cover.

Vergents thickness map from the melting season thread has a rather thick patch at Kane basin.
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Laurent

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Re: The Nares Strait thread
« Reply #648 on: June 20, 2015, 07:44:37 PM »
The ice is collapsing inside Nares strait.

Tor Bejnar

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Re: The Nares Strait thread
« Reply #649 on: June 20, 2015, 11:09:23 PM »
20-06-2015 [Sentinel-1] from DMI:  I find this very interesting that the ice bridge in Kane Basin is holding but the ice 'behind' it is cracking/breaking up.  Soon (I'm sure) a crack will break the bridge.  The ice, it appears, took my joke seriously (some time back) that 'the ice wants out of Nares Strait and if it has to get out through the Lincloln Sea, then so be it'!
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