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Author Topic: PIG has calved  (Read 184768 times)

AbruptSLR

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Re: PIG has calved
« Reply #650 on: February 04, 2017, 06:10:52 PM »
Here is a gif from Jan 5 (?) to Feb 1 of the rift in the SW Tributary glacier next to PIG from

Thanks for this nice gif sequence highlighting the opening of the rift in the SW Tributary ice shelf.  The attached image shows a Sentinel 2 image from Feb 2 2017 of both the PIIS and the SW Tributary ice shelf, to which I have added a segmented yellow line indicating the approximate location of where I am concerned that the next upstream crack will occur in the PIIS as the rift in the SW Tributary ice shelf continues to open.  If I am correct, the opening of such an upstream crack would cause a major calving event along the location of the current crack in the PIIS.
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Wipneus

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Re: PIG has calved
« Reply #651 on: February 15, 2017, 08:47:54 AM »
The recent calving is the subject of Nasa's Earth Observatory Image of the Day

Glacial “Aftershock” Spawns Antarctic Iceberg

The discussion mentions: ‘rapid fire’ calving

Jim Hunt

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Re: PIG has calved
« Reply #652 on: February 15, 2017, 01:10:38 PM »
The recent calving is the subject of Nasa's Earth Observatory Image of the Day

In addition NASA's first reference is to this very forum.

Well done SolarTim, Wipneus et al.!
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oren

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Re: PIG has calved
« Reply #653 on: February 15, 2017, 02:16:01 PM »
I actually missed the ASIF reference at first. Nice!

DrTskoul

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Re: PIG has calved
« Reply #654 on: February 15, 2017, 03:23:31 PM »
Testament to the superb scientific discovery and analysis work done at AIF!!
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solartim27

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Re: PIG has calved
« Reply #655 on: April 17, 2017, 09:58:51 PM »
Thinking more about the lateral compression, it seems that there is a compression from the opposite side, a bit further down. This pushed the calving face to the river right, after passing Evans Knoll.

I suspect, but can't prove, that this deformation force increases the backpressure on the rest of the glacier, as it forces the visible bend to the river right.

I suspect that this deformation was part of the reason the calving broke off the way it did (first the river right, the the river left last, as it was in compression for the longest). I think this may be a protective factor, decreasing the chance of a large calving soon. I hope.

I worry about the rate of decline once the calving front passes those lateral pinning points.  That's when it'll really start flying. :(

A is the compression force due to Evans Knoll, B is the one on the opposite, causing the flexion around Evans Knoll.

I was surprised that PIG didn't go this summer, but it still looks like it can go at any time, as we are seeing increasing amounts of minor calving at the notches to either side of PIG. 

I believe the compression from the SW Trib described above is keeping it penned in.  There is a good image on that post, worth going back to review.
Click to animate and zoom in for a closer look. Dates are 23 Mar to 16 Apr.

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170416T042746_5C37_S_1.final.jpg

S1A_EW_GRDM_1SSH_20170323T042745_D14E_S_1.final.jpg
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solartim27

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Re: PIG has calved
« Reply #656 on: April 22, 2017, 07:32:41 AM »
Here is a quick look over the past year.  See anything disturbing?  Click to animate.
(Tried a smaller version, 1 MB, it works!)(Oh well, I'm going to bed.  Here are the 2 pics, go full screen and toggle between them to your hearts content.  I was looking at the rifts between PIG and the Trib)

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170420T035503_D89B_S_1.final.jpg  (38 MB)

S1A_EW_GRDM_1SSH_20160331T045150_542F_S_1.final.jpg  (35 MB)

« Last Edit: April 22, 2017, 07:47:03 AM by solartim27 »
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Darvince

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Re: PIG has calved
« Reply #657 on: April 22, 2017, 07:35:16 AM »
Forum software decided to not animate it for some reason, just to let you know.

oren

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Re: PIG has calved
« Reply #658 on: April 22, 2017, 08:42:12 AM »
Forum software decided to not animate it for some reason, just to let you know.
It's probably too large. If you limit to 700 pixel width it should work.
Edit: the last one works.

solartim27

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Re: PIG has calved
« Reply #659 on: May 03, 2017, 03:39:22 AM »
Looks like the rift has made it to the notch at the top of the screen (to me).  Maybe it'll go with the next full moon?  Click to animate, (1.6 MB).
Apr 20 to May 2

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170502T035504_E082_S_1.final.jpg (40 MB)

S1A_EW_GRDM_1SSH_20170420T035503_D89B_S_1.final.jpg (40 MB)
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Wipneus

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Re: PIG has calved
« Reply #660 on: May 07, 2017, 10:08:58 AM »
The pixel noise in these Sentinel radar images make it hard to be sure. But it looks as some more opening/deepening at the ends of the crack.

nukefix

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Re: PIG has calved
« Reply #661 on: May 07, 2017, 05:02:28 PM »
The pixel noise in these Sentinel radar images make it hard to be sure. But it looks as some more opening/deepening at the ends of the crack.
Yes, if there's coherence InSAR would be the way to see the progress for sure.

solartim27

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Re: PIG has calved
« Reply #662 on: June 05, 2017, 09:09:41 PM »
Wonderful. Here is a sequence 12 days apart, that means the Sentinel is in identical orbital position.
Resolution of the image is 120m/pixel, implying the width of the image is about 68km.
There are hi-res images available from the 24th and 25th
A nice view of the last breakup 2 years ago, the posts before and after this have some good shots as well. 

I believe we are right on track for a very similar collapse of the soon to be newly calved berg.  Here is a gif from 14 May to 5 Jun ( Click to animate 1.7 Mb) with two close ups of the notch areas, posted seperately.  Note the new calving in the north notch.

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170605T041129_35BA_S_1.final.jpg (55 Mb)

S1A_EW_GRDM_1SSH_20170514T035505_4E16_S_1.final.jpg (40 Mb)
« Last Edit: June 05, 2017, 09:31:13 PM by solartim27 »
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solartim27

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Re: PIG has calved
« Reply #663 on: June 05, 2017, 09:24:36 PM »
Here are the smaller gifs, and a shameless self promotion, crack propagation looks like just before the last calving with the lower resolution
BYE BYE
« Last Edit: June 05, 2017, 09:30:04 PM by solartim27 »
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AbruptSLR

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Re: PIG has calved
« Reply #664 on: June 08, 2017, 05:51:39 PM »
While it is obvious in other earlier images, I attach an image from June 6 2017 to highlight the fact that there is a crack that extends almost all the way through the width of the Southwest Tributary ice shelf; which will eventually lead to a major calving event from this critical ice shelf.
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solartim27

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Re: PIG has calved
« Reply #665 on: June 19, 2017, 05:43:19 PM »
Here is a gif from 7 Jun to 19 Jun of the southern PIG / Tributary boundary.  It looks to me that the rift has had a significant extension.  I wonder how far back the calving will go when that cork blows out.  Looking back at the calving 2 years ago, it went right as the rift came in line with the mountain peak to the north (not in this image), which is right where the rift is now.  (Click)

http://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SSH_20170619T035507_39F5_S_1.final.jpg

S1A_EW_GRDM_1SSH_20170607T035506_EDB2_S_1.final.jpg
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Wipneus

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Re: PIG has calved
« Reply #666 on: July 07, 2017, 07:35:09 PM »
Signs of an upcoming calving. There is a new crack (left arrow) that became visible a few weeks ago and is getting clearer with every new image. Also the big crack that we have recognized a couple of years ago gets longer (second arrow) which could lead to a much bigger calving of course.

solartim27

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Re: PIG has calved
« Reply #667 on: July 13, 2017, 06:06:56 PM »
Guess we'll have to wait at least one more lunar cycle.  Maybe with the new moon?
S1A_EW_GRDM_1SSH_20170713T035508_7376_S_1.final.jpg
S1A_EW_GRDM_1SSH_20170605T041129_35BA_S_1.final.jpg
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Ajpope85

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Re: PIG has calved
« Reply #668 on: July 13, 2017, 06:34:41 PM »
Is it usual to have large cracks propagating or large calving events in the winter?

AbruptSLR

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Re: PIG has calved
« Reply #669 on: July 13, 2017, 07:28:53 PM »
Is it usual to have large cracks propagating or large calving events in the winter?
It is usual to have calving events in the winter as sea ice offers little buttressing action against a large calving.  What is unusual is for the calving face on PIIS to located so far upstream.  This is a sign that global warming is advecting relatively warm water into the cavity beneath the ice shelf.  If/when the small ice shelf for the SW Tributary glacier also calves (possibly during the next major PIIS calving event in the next one to nine months) this should reduce buttressing on the SW Tributary glacier which would cause its ice flow velocity to increase.
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Wipneus

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Re: PIG has calved
« Reply #670 on: July 14, 2017, 11:58:16 AM »
See my previous post on the 7th for an overview. This can not last long.

silkman

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Re: PIG has calved
« Reply #671 on: July 14, 2017, 12:05:50 PM »
Wipneus

What's the scale of this incipient event, relative to the Larsen C calving?

Wipneus

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Re: PIG has calved
« Reply #672 on: July 14, 2017, 12:36:31 PM »
Wipneus

What's the scale of this incipient event, relative to the Larsen C calving?

This one is 10m per pixel. So this image is 7kmx7km.
I do expect the eventual calving to be bigger than this, but nothing like Larsen C. The PIG calves far more often though, when the big crack (see my posting on 7/7) goes it will be the third big calving in the history of this thread.

solartim27

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Re: PIG has calved
« Reply #673 on: July 15, 2017, 05:02:40 PM »
This tweet has a nice video from the ice bridge flight  from 11/2016, crossing from PIG to the SW Tributary
https://mobile.twitter.com/peter_neff/status/880067456131379203
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solartim27

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Re: PIG has calved
« Reply #674 on: July 23, 2017, 07:57:53 PM »
5 days, July 18 to 23.  Large motion, with big rift development behind the main crack.  Click to animate
S1A_EW_GRDM_1SSH_20170718T040320_7B12_S_1.final.jpg
S1A_EW_GRDM_1SSH_20170723T041131_F2E2_S_1.final.jpg
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Tor Bejnar

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Re: PIG has calved
« Reply #675 on: July 23, 2017, 11:56:22 PM »
Given what we can see between the two images, I wonder what the inter-a-what-cha-ma-call-it-feromitor "interferometry" (used on Larsen C by Project MIDAS, showing details we couldn't see) shows.
Arctic ice is healthy for children and other living things.

AbruptSLR

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Re: PIG has calved
« Reply #676 on: August 13, 2017, 07:02:46 PM »
It is starting to look like the PIIS (and the SW Tributary Ice Shelf) may calve before the coming austral summer:

“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Wipneus

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Re: PIG has calved
« Reply #677 on: September 13, 2017, 07:01:24 PM »
An overview in 40m/pix (from the original 10m/pix) of the developing cracks in the Pine Island Glacier. Things are progressing very gradual without stalls and may continue to do so for a while.
The main crack, labeled "1" has widened to about 240m, twice the width of a year ago.
The crack "2" has developed for a few months now and is getting more visible by the week (width very small).
Crack "3" was clearly visible by the Sentinel 2 images, never as  clearly by S1. Hope we get to see optical images soon again.
The feature labeled "4" may be the next major crack, visibility still low but persistent over a few scans from the S1 satellites.

PS. Between the images the glacier moved 140m (measured at the great crack). That is about 11.5m/day. Slightly speeding up IIRC, but I really should repeat the measurement with images further apart.

Wipneus

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Re: PIG has calved
« Reply #678 on: September 18, 2017, 04:58:00 PM »
The visual season has begun in the Landsat offering.

Here is an animation in 45m/pix gving an overview of  the progress in 7 months. The images where shifted/rotated relative to each other to align at the upper edge of the "great crack".