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Author Topic: Pine Island Glacier (PIG) Calving and Discussion  (Read 738014 times)

AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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.!
"The most revolutionary thing one can do always is to proclaim loudly what is happening" - Rosa Luxemburg

oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« Reply #654 on: February 15, 2017, 03:23:31 PM »
Testament to the superb scientific discovery and analysis work done at AIF!!

solartim27

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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 because "we cannot negotiate with the melting point of ice"

AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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:

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Wipneus

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Re: Pine Island Glacier (PIG) Calving and Discussion
« 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: Pine Island Glacier (PIG) Calving and Discussion
« 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".

maga

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #679 on: September 22, 2017, 08:24:33 PM »
Action at PIG!

Aluminium

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #680 on: September 22, 2017, 11:37:27 PM »
Two screenshots from EOSDIS.

oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #681 on: September 22, 2017, 11:53:55 PM »
I know it's been expected on this forum for months but it's still jaw-dropping.
I believe PIG is in record retreat and the SW tributary has lost major buttressing (can't verify this atm though).

AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #682 on: September 23, 2017, 12:26:34 AM »
I know it's been expected on this forum for months but it's still jaw-dropping.
I believe PIG is in record retreat and the SW tributary has lost major buttressing (can't verify this atm though).

I concur that the PIIS is in record retreat, but it is not clear to me that the SW tributary has yet lost major buttressing.
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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #683 on: September 23, 2017, 11:08:13 AM »
I also don't think that the SW tributary did already loose a lot of buttressing. I'm rather more worried about the front of it breaking away. I imagine PIG speeding up as a consequence and the western shear zone slipping through the new opening (where currently the half-calved berg sits). This should rapidly weaken the western shelf of PIG even more and eventually it won't be able to keep up pressure on PIG which in turn will retreat at least until the end of the bay somewhere around the position where the grounding line is plotted in the Modis pictures. From there I expect slower retreat in a different style, similar to Jakobshavn.

maga

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #684 on: September 23, 2017, 02:36:34 PM »
Polarview has it as well now. Interesting crack across the berg. Must have been quite some pressure on the western tip!

AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #685 on: September 23, 2017, 06:42:22 PM »
I also don't think that the SW tributary did already loose a lot of buttressing. I'm rather more worried about the front of it breaking away. I imagine PIG speeding up as a consequence and the western shear zone slipping through the new opening (where currently the half-calved berg sits). This should rapidly weaken the western shelf of PIG even more and eventually it won't be able to keep up pressure on PIG which in turn will retreat at least until the end of the bay somewhere around the position where the grounding line is plotted in the Modis pictures. From there I expect slower retreat in a different style, similar to Jakobshavn.

I generally concur with your concerns, but it would be helpful if you would replace the term 'western' with 'southwestern'.  Also, the 'front' of the SW tributary glacier is the Southwest Tributary Ice Shelf, STIS.
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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #686 on: September 23, 2017, 07:34:24 PM »
Let me try an animation of the event (did not work in another thread).

oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #687 on: September 24, 2017, 12:16:05 AM »
I believe PIG is in record retreat and the SW tributary has lost major buttressing (can't verify this atm though).
Turns out verification is important... the last major calving of the PIG happened around Aug 1st 2015 (If I am not mistaken). Turns out the new PIG calving front near the SW tributary is at the same location as the front in 2015, and in general the whole front is in record retreat but just barely. Apologies for the lousy resolution. And for unverified assumptions.
In addition, can the honored folks here confirm that the new calving is based on a crack that has been developing since 2015? This was my impression as I browsed up-forum.
If the past is any indication, one side of the new berg - on the left in the animation - could become grounded for a while. Will be interesting to watch.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #688 on: September 24, 2017, 04:16:45 AM »
Turns out verification is important... the last major calving of the PIG happened around Aug 1st 2015 (If I am not mistaken).

I believe that last major calving of the PIIS occurred some time between July 23 and July 30, 2015.
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oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #689 on: September 24, 2017, 08:34:58 AM »
Twitter link provides a better animation as well as a reminder of previous calving front locations.
https://twitter.com/StefLhermitte/status/911722449225515008
And an animation (posted Jan 17) showing rift progression since 2015.
https://twitter.com/StefLhermitte/status/826364887106457600
Can anyone estimate the next breaking point on the main PIG? I can't see any new crack coming up.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #690 on: September 24, 2017, 09:19:10 AM »
You left out this one oren:

https://twitter.com/StefLhermitte/status/911712305049751558

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #691 on: September 24, 2017, 07:20:41 PM »
In addition, can the honored folks here confirm that the new calving is based on a crack that has been developing since 2015? This was my impression as I browsed up-forum.

Yes. The major crack involved in this event was noticed some time before the 2015 event. It can be found tracing this thread back.

There is a possible new crack that I noticed in this post. It is also visible on the latest clear Landsat image, but very vague: the snow must be thick and the crack thin. See attached image which has undergone some contrast enhancements.

If(!) the crack develops into the new calving, it will be smaller than the three previous ones. About one third I would say.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #692 on: September 24, 2017, 10:07:49 PM »
Quote
visible on the latest clear Landsat image, but very vague: the snow must be thick and the crack thin.
Indeed it's hard to draw out that feature ....

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #693 on: September 26, 2017, 03:27:14 PM »
The linked article highlights the role of warm ocean water in causing the PIIS to thin and accelerate; however, they do not acknowledge: (1) the interaction between the PIIS and the SW Tributary Ice Shelf; nor (2) the potential influence of hydrofracturing (as discussed by DeConto & Pollard 2016) on accelerating calving as GMSTA approaches 2.7C:

Title: "Yet Another Giant Iceberg Has Broken Free From Antarctic"

https://gizmodo.com/yet-another-giant-iceberg-has-broken-free-from-antarcti-1818729430

Extract: "Shuman also confirmed that the rifts are forming in the center of the glacier and extending out toward the edges. This means that the rifts are forming far inland, likely the result of warm ocean water rubbing against the base of the glacier. This may explain why the calving events are happening with increased frequency (the speed of the glacier’s flow towards the sea is increasing, and it’s now moving at about 2.5 miles (4 km) per year), and why PIG appears to be thinning (the rate of thinning has quadrupled since the mid 1990s). If this current rate of thinning continues, the entire main trunk of the glacier could be afloat in about 100 years."
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AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #694 on: October 06, 2017, 12:26:30 AM »
Here is a Landsat 8 image from Sept 28 2017

https://earthobservatory.nasa.gov/IOTD/view.php?id=91066
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AbruptSLR

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #695 on: October 06, 2017, 12:42:54 AM »
Attached is a Sentinel-1 image of the PIIS from Oct 4 2017, that clearly indicates that Iceberg B-44 is not pinned and is floating away from the ice shelf.
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Wipneus

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #696 on: October 11, 2017, 06:29:21 PM »
The calving breaks, partly along known cracks.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #697 on: October 14, 2017, 03:59:31 PM »
Also the Sentinel 2 season has begun. Breathtaking quality, but too late for the latest calving.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #698 on: October 14, 2017, 07:08:11 PM »
The detail (windswept snow across the calved iceberg, the shape and condition of the small bergs, some toppled over, others upright, the shadows cast by the sun, low in the horizon, the icy blue patches of water, tinted by the crumbling and spreading out of ancient ice of the glacier) is amazing.

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #699 on: October 14, 2017, 08:13:01 PM »
Shared Humanity.

Indeed - niveo-aeolian glacio-mechanics seems to be a new subject of rising importance. The drifting away of icebergs is also the result of aeolian processes. The infilling of the two or three crevasses already visible up-stream is a complex niveo-aeolian phenomenon. At some stage - when the ice cliff becomes high enough - the mechanics will take over.
« Last Edit: October 14, 2017, 08:18:16 PM by P-maker »