Pine Island Glacier (PIG) Calving and Discussion

[paolo]

An interesting development in the SIS: under the action of the SWT the tip of the fractured zone on the T11 side has fractured, the R1 rift (see last image of the animation) will no longer be directly solicited by the SWT push and its future development will depend on the evolution of the next rift (R2). It is therefore possible that the action of the SWT could, in the near future, be limited to demolishing the ice shelf between the SWT and T11 (noted in the last image by IS, note the fracture zone downstream of an Ice Rumple which separates this part of the ice shelf from T11).
The animation is built from the images between 28/10 and 12/15 (one for every twelve days; the first three, all from 28/10, being a zoom on the area of interest and the last two from 15/12 (the last one being the large scale and commented version)

To animate click once and click again to display it fully expanded

[baking]

12-Day GIF of Pine Island Bay (96x112 km) showing new cracks in the sea ice.  Worldview images from today confirm that this sea ice has already floated away.  Also note the icebergs near SWT have shifted due to a growing polynya.

[paolo]

Looking further east, where the PIG and the upstream part of the SIS (compacted and dragged by the PIG) meet the eastern side of T11 (the separation between the eastern part of the SIS and T11 being marked by the fractured part downstream of the Ice Rumple indicated by IR in the last image of the animation; you can also see further west (below) the fracture zone marking the western flank of T11 which I mentioned in the previous post), you can see the effects of compression on the eastern flank of T11.

Note the block between the two rifts noted R1 and R2 is being flexed, hence the particularly marked widening of R2

It seems that the damage in T11 should be limited and, taking also into account what we have just seen in the previous post, that T11 should come out of it without too much damage in the near future with even the future possibility of an advance of T11 leading to a temporary closure of the DZ (slowing down the inevitable retreat of PIG)

The animation is built from the images between 04/10 and 12/15 (one every twelve days; the first three, all from 04/10, being a zoom on the area we are interested in and the last two from 15/12 (the last one being the large scale and commented version)

To animate click once and click again to display it fully expanded

[paolo]

Finally, an update of the SWT with a zoom on the western front

The effects of the change in direction (including the opening of the Internal Damage Zone) and the actions of some Ice Rumples (that are still holding the ice shelf and causing its complete tearing) are evident


The animation is built from the images between 04/10 and 12/15 (one for every twelve days; the first three, all from 04/10, being a zoom on the area we are interested in and the last two from 15/12 (the last being the commented version)

To animate click once and click again to display it fully expanded

[Stephan]

Thank you paolo for these new analyses. The longer period of your gifs is very much appreciated.

[Stephan]

New cracks in the "blumencrack area" at the NE flank of PIG.

In the last two weeks two new cracks have developed in the area that our former member blumenkraft has intensively studied years ago - that's why I call this area the "blumencrack area". The two new cracks are visualized by two red arrows. Below (left of) that area the flow direction splits up (lemon arrows) which in my opinion destabilizes the glacier.

The northeastern part (upper right corner) of that picture (size is approx. 14*8 km) shows the area in which the ice is almost immobile (dashed orange line) and which is not part of the PIG itself. Correction: North is up, not left!

To put this picture into the greater context I add a second picture in which you can find the area of the first picture located in the green box.

[grixm]

The fast ice outside the PIG seems to be primed to shatter for the first time in three years if I remember correctly. There is extensive cracking on all sides (circled in red).

[paolo]

This is an event worthy of a post!
> Complete break-up of the sea ice
And, no longer held in place by the sea ice :
> Departure of the set of icebergs, in which the PIG iceberg had fractured while remaining in contact with the PIG
> Departure of a whole set of icebergs from the western front of the SWT

Animation with images from 17/01/2023 and 29/01/2023

Large images (2000x2000 px), click to animate and click again to enlarge completely

[baking]

Smaller 12-day GIF.  Image is 100km on a side.

[Espen]

And a Jan 24 - Jan 29 2023 version:

Please click to enlarge and animate!

[paolo]

Espen,
the problem with animations using a delay of less than 12 days is that, because of the different orbits, the images are not aligned and move even the parts that should stay fixed, like for example the Ice Rise in the west of the SWT and suddenly you don't know what is really moving and what is not.

That's why baking and I almost always use a 12-day delay between images (just today I tried, as an exception, an animation with a 2-day delay, before abandoning it and publishing the animation with the 12-day delay)

[Espen]

I see no problems aligning them?

[paolo]

Espen,
       
       “I see no problems aligning them?”

Attached is a zoom on the SWT (12 day delay) to show the problem.

The icebergs surrounded by the yellow circle are grounded and should not move (as well as the whole edge of the ice rise west of the SWT, below these icebergs, which should not move either).
In your animation they do move (the orbits are different and the same points are not referenced with the same coordinates, which explains the false motion)

But you are right, my animation was overexposed (but it had to be done quickly, the subject was hot ), I corrected (in this animation).

[Espen]

That is for the nitpicking department to decide

[oren]

I find <12 day animations useful, as long as people are aware of the limitations, which I think most readers here are.

[gerontocrat]

I find <12 day animations useful, as long as peoe are aware of the limitations, which I think most readers here are.

This old person thinks the 12 days gap is great. You get a much clearer picture of the scale of changes between the two images. Seeing a gradual change from daily images can obscure the significance of the change, i.e. the fast ice which helps to restrain the flow of the glacier is no more, giving a very few weeks of open water in front of the glacier. It will be interesting to see any effect on glacier flow and further icebergs breaking free from the glacier front before winter freeze up sets in.

Please please keep the 12 day gifs going.

[Espen]

Next door Pine Island Glacier you will find Ferrero Bay and Cosgrove Ice Shelf, where there are signs of the shelf ice losing touch with the coast of Canisteo Peninsula similar signs are seen at Abbot Ice Shelf, follow the RED arrows.

Please click on image to enlarge and animate!

[paolo]

This is an artefact.
Between two images with a delay < 12day, not only, as I pointed out, the positioning can change, but also the rendering since the angle of the image taking is not at all the same (this is a classic and some crevasses can disappear/appear from one image to the other)
But in this case it is likely that it is only an accumulation of water in the division between the flat part and the sloping part.

[Espen]

This is an artefact.
Between two images with a delay < 12day, not only, as I pointed out, the positioning can change, but also the rendering since the angle of the image taking is not at all the same (this is a classic and some crevasses can disappear/appear from one image to the other)
But in this case it is likely that it is only an accumulation of water in the division between the flat part and the sloping part.

Your opinion has been received!

[paolo]

Attached are two animations:

The first animation is a zoom on a point shown by Espen from screenshots on the REMA website:
The first three images are a progressive zoom on this point
In the fourth one I added the level curves (10 m)
In the fifth I have added the profile of levels along the red line and highlighting the deepest point.
Click to animate and click again to enlarge the images

The second animation is given by the zoom on the same point from the S1 images of 05, 17 and 29 January.
In the first image (15 Jan) we see that the firm of the ice shelf was completely saturated with water.
In the next image we can see that most of the ice shelf has dried up, except for the edge of the ice shelf in the edge depressions
In the last one the water persists only in the deepest points (note: in Espen's animation the image with the most marked black spots is the one from 24/01 and not the one from 29/01)

I think that this information should close the small debate.

[Espen]

This is an artefact.

You named it!

[Chris83]

Polarview today
(Was zoomed in)

[baking]

Today's high resolution 12-day GIF of the Southwest Tributary (SWT.) Image is 24 x 20 km.

[paolo]

This animation, which contains the images from 04 October to 20 January, is a zoom on the large iceberg south of the PIG front

Note: tomorrow we will have the new image of the PIG, but it will not give any further information on what I want to show. However, from tomorrow I will publish long animations of the DZs (Damage Zones) with tomorrow's image as well.
This iceberg calved in January (see the last two images: "Before the iceberg calves", from 08 Jan, and "After the iceberg has calved", from 20 Jan)

This calving (two calvings: top and bottom right) does not seem to depend on the opening of the polynya and indeed it was already free from the grip of the sea ice and there were almost no signs of separation before calving. It seems rather to depend on the warmer current, which comes out of the PIG in correspondence of the SSM (Southern Shear Margin) and which is at the origin of this polynya, current which melted and widened rifts already existing in the base of the iceberg (and thus not visible from above)

In this animation it is also evident that the opening of the polynya at the end of October had already set the iceberg and ice mixture in motion again.

Click to animate and click again to enlarge the images completely (1700x2000 px)

[paolo]

The animation presented below aims to show the very strong movements observed between 29/01 (the day after the fast ice debacle) and today

Remarks :
> To highlight these movements, I have traced the displacement of some icebergs. We can think that the marine currents were also helped by strong winds. We can also note
the very strong dispersion of the icebergs.
> One of the icebergs, for which I noted the displacement, broke in two (those who follow the discussion can recognize it, it is an iceberg which had detached from the NIS a long time ago; remarkable fact it broke on this occasion)
> A new calving of the NIS coast has taken place (it was expected)
> The two images are not perfectly aligned, as the two images are not homogeneous (20/01 low resolution and 01/02 high resolution)
> As always there was no manual alignment, the positioning is done by QGIS using the TIFF image information

Click to animate and click again to enlarge the images

[Espen]

Pine Island Glacier High Resolution Animation: Jan 20 2023 and Feb 1 2023.

Please click on image to enlarge and animate!

[Espen]

Pine Island Glacier High Resolution Animation: Jan 27 2023 and Feb 3 2023.

Please click on image to enlarge and animate!

[paolo]

To the documents produced from QGIS, the satellite images among others, I add geographical information (latitudes and longitudes) and, if their display is not useless and does not hinder the understanding and reading of these images, historical information relating to the front lines and grounding lines obtained from these databases:
> MEaSUREs Antarctic boundaries (green line; with data for the years 2007/2009)
> USNIC_Antarctic Ice Shelf Data (yellow line; from early 2019 or earlier)
> SCAR_ADD-Antarctic Digital Database v7.3 (orange line; from early 2020)
> SCAR_ADD-Antarctic Digital Database v7.4 (red line; from early 2021)
> SCAR_ADD-Antarctic Digital Database v7.5 (lilla line; from early 2022)
and, new databases,
> SCAR_ADD-Antarctic Digital Database v7.6 (violet line; from late summer 2022)

Stefan rightly asked me about the meaning of these lines, but their actual content, especially the date of their update, depends on the sector we are dealing with and the official information, which you will find at the end of the post, is not always sufficient.
For this reason, for each sector that I will deal with, I will write a post to give the S1 images that, with their frontline, come closest to the frontlines of these DBs. And in the following posts, related to the same sector, I will refer to this post.
This post corresponds to the PIG sector.

You will find below :
> The Modis image of 31-10-2008 which gives the indicative date for the MEaSURE database (in this case I preferred to work from a less zoomed image)
> An animation containing the S1 images zoomed in on the front: from 11-04-2019 (USNIC), from 05-04-2020 (ADD 7.3), from 12-04-2021 (ADD 7.4), from 07-04-2022 (ADD 7.5) and from 05-04-2020 (ADD 7.6)
> A non-zoomed image of the PIG with all databases displayed

Remarks :
> In the USNIC and ADD 7.3 databases a grounding line is used, which, in relation to the SWT, is obsolete and wrong (it gives it fully grounded to the front). This is understandable in the extreme. What surprises me completely is USNIC which marks the presence of the ice shelf in the part of the so-called grounded area that has calved! ADD 7.3 uses the same grounding line, but at least corrects the grounded area by cutting out the calving part. The other databases all use a different grounding line, which, relative to the SWT, is correct (so in total we have two grounding line models).
> Clearly the positioning of the images and that of the database do not coincide (no miracle). I have tried to choose the image at the right date as best as possible.

Click to enlarge (and animate the second image) and click again to enlarge completely

Official information on these databases:
> MEaSUREs Antarctic boundaries (green line; with data for the years 2007/2009)
The maps are assembled from 2008-2009 ice-front data from ALOS PALSAR and ENVISAT ASAR data acquired during International Polar Year, 2007-2009 (IPY), the InSAR-based grounding line data (MEaSUREs Antarctic Grounding Line from Differential Satellite Radar Interferometry), augmented with other grounding line sources, the Antarctic ice velocity map (MEaSUREs InSAR-Based Antarctica Ice Velocity Map), and the Bedmap-2 DEM.

> USNIC_Antarctic Ice Shelf Data (yellow line; from early 2019 or earlier)

> SCAR_ADD-Antarctic Digital Database v7.3 (orange line; from early 2020)

> SCAR_ADD-Antarctic Digital Database v7.4 (red line; from early 2021)
Major changes in v7.4 include updates to coastline and ice shelves between Gipps Ice Rise and Ronne Ice Shelf, updated ice shelf fronts for Brunt, Stange and West ice shelves, Pine Island Glacier, and an updated coastline for Adelaide Island.

> SCAR_ADD-Antarctic Digital Database v7.5 (lilla line; from early 2022)
Major changes in v7.5 include updates to ice shelf fronts in the following regions: Seal Nunataks and Scar Inlet region, the Ronne-Filchner Ice Shelf, between the Brunt Ice Shelf and Riiser-Larsen Peninsula, the Shackleton and Conger ice shelves, and Crosson, Thwaites and Pine Island. Small areas of grounding line and ice coastlines were also updated in some of these regions as needed.

> SCAR_ADD-Antarctic Digital Database v7.6 (violet line; from late summer 2022)
Changes in v7.6 include updates to the Amery Ice Shelf front, ice shelves and glaciers east of Law Dome, and sections of coast and ice shelf around Abbot Ice Shelf and Pine Island Glacier.

[paolo]

I extend a bit the history shown in the previous post by using the map from the "Coastal-Change and Glaciological Maps" series
I start by presenting an extract related to the PIG in the original format to allow an easier reading (after loading in QGIS it is more difficult to read because of the rotation)
I add the legend of this map and I finish with an animation in which I add to this map (loaded in QGIS)
> the "Coastal-Change and Glaciological Maps" map
> the previous image plus front line from MEaSURE
> the previous image plus front line from USNIC
> the previous image plus all front lines from ADD (7.3, 7.4, 7.5 and 7.6)
It can be noted that in 2008 (MEaSURE) the positions of the previous decades were maintained. Unfortunately, this is no longer the case with the other fronts ...


Click to enlarge (and animate the second image) and click again to enlarge completely

PS: I will publish the long S1 image series, which I promised, starting tomorrow

[sidd]

Thanks. Could you put a compass rose or just an arrow indicating North

sidd

[paolo]

Before dealing with the SWDZ (South West of the Damage Zone), I wanted to build up a very, very long series of images relating to the friction zone between the PIG and the SWT.

I used one image per southern summer, when available (for the summer of 2005/2006, a Modis image was available, but I discarded it because of the very low resolution of the Modis images).

This gave the 28 images, of varying quality depending on the source available.

Each image has in the title the date and the source

Images are 1000x1000px, click to animate

[sidd]

Nice. Thanks.

sidd

[grixm]

Long time coming.

[baking]

12-Day GIF of the calving.

[baking]

12-day GIF of the Southwest Tributary (SWT.)  Notice the new crack to the right.

[IceConcerned]

Thank you Paolo for this animation.
M'y impression is that thé bigger longitudinal iceberg stick between pIG and SWT, which is acting as a Cork to thé DZ, is about to get lose. I would this expect thé DZ to get flushed out in thé coming weeks.

[paolo]

And now the smart guy is being secretive.
The PIG has recently calved!

In the Sentinel1 image of 15/08 the calving has not yet taken place, but, given the movement of the pieces, I think it must have taken place between this image and the 16th, maximum the 17th. Normally on the 17th we should have had a low resolution Sentinel1 image, but this was not the case. The displacement of the pieces was important, so it was not noticed on a quick look at the Sentinel1 image of the 20th.

In the first animation you will see the Sentinel1 images of 08 and 20 as well as the image of 08 with the added information about this calving

The second animation contains the two images of 08 and 20 from the bay to show the calving and the extent of the displacement.

Large images, click to animate

[Stephan]

Nice catch, paolo. And remarkable how far the icebergs have traveled...

[grixm]

And now the smart guy is being secretive.
The PIG has recently calved!

Thanks for the distance markers, I often take the scale for granted after looking at satellite images but it's crazy to let it sink in that this relatively small chunk is still bigger than the entire city I live in.

[Often Distant]

A 9 year gif focusing on the inland higher elevation break point not visible on worldview.
Plus an image from 2012 which at the time was focused on the crack at the front end before the calving that begun the thread in 2013. Found here:

https://www.esa.int/Applications/Observing_the_Earth/Envisat/Earth_from_Space_Pine_Island_cracked

Earlier images are hard to find. Comparison is not easy. Out there somewhere. Will keep searching.

[baking]

A 9 year gif focusing on the inland higher elevation break point not visible on worldview.
Plus an image from 2012 which at the time was focused on the crack at the front end before the calving that begun the thread in 2013. Found here:

https://www.esa.int/Applications/Observing_the_Earth/Envisat/Earth_from_Space_Pine_Island_cracked

Earlier images are hard to find. Comparison is not easy. Out there somewhere. Will keep searching.

What exactly are you looking for?  Some of us have collected images over the years.

[Often Distant]

Earlier images are hard to find. Comparison is not easy. Out there somewhere. Will keep searching.

What exactly are you looking for?  Some of us have collected images over the years.

Simple satellite imagery data stretching back further decades as far as possible. 1970's?
Any random dates that can display the crevices feature location.

[grixm]

I posted some images and comments in the Thwaites thread that can be related to PIG too: https://forum.arctic-sea-ice.net/index.php/topic,1760.msg379845.html#msg379845

[baking]

Large 12-day GIF of the Southern Shear Margin (SSM) showing a large iceberg splitting in two as it gets caught between the Southwest Tributary (SWT) and PIG (bottom of image) and a calving at the upstream end of the melange.

[grixm]

There was also a small calving on the tongue itself. The darker section on the below composite image.

[paolo]

Business recovery

Today, between the PIG and the SWT, there has been a small collapse.

Please find enclosed two animations:
> the first with three coherent images (same orbit, 12 days apart)
> the second with yesterday's image (high resolution) and today's (low resolution). The movement we see is clearly due to the fact that the orbits of the two images are not coherent with each other, and consequently the two images are not aligned.

Click to animate and click again to enlarge the images completely.

[IceConcerned]

The lock between PIG and st low-res. Sentinel picture
We can expect the rubble separating PIG from T11 to flow out more freely from now on

https://www.polarview.aq/images/105_S1jpgfull/S1A_EW_GRDM_1SDH_20230919T042019_912E_S_1.final.jpg

[grixm]

First Sentinel-2 images of the season is out!
Nothing too interesting, clouds cover the southern shear margin.
I do see one thing though, that wasn't so visible on radar. The chunk on the edge of the southern part of the glacier actually has a crack going all the way through. Looks like it's barely hanging on and could detach at any moment.

https://apps.sentinel-hub.com/eo-browser/?zoom=10&lat=-75.02891&lng=-101.15387&themeId=DEFAULT-THEME&visualizationUrl=https%3A%2F%2Fservices.sentinel-hub.com%2Fogc%2Fwms%2F42924c6c-257a-4d04-9b8e-36387513a99c&evalscript=Ly9WRVJTSU9OPTMKZnVuY3Rpb24gc2V0dXAoKSB7CiAgcmV0dXJuIHsKICAgIGlucHV0OiBbIkIwNCIsIkIwMyIsIkIwMiIsICJkYXRhTWFzayJdLAogICAgb3V0cHV0OiB7IGJhbmRzOiA0IH0KICB9Owp9CgpmdW5jdGlvbiBldmFsdWF0ZVBpeGVsKHNhbXBsZSkgewogIHJldHVybiBbMSAqIHNhbXBsZS5CMDQsMSAqIHNhbXBsZS5CMDMsMSAqIHNhbXBsZS5CMDIsIHNhbXBsZS5kYXRhTWFzayBdOwp9&datasetId=S2L1C&fromTime=2023-09-24T00%3A00%3A00.000Z&toTime=2023-09-24T23%3A59%3A59.999Z&gamma=1.5&demSource3D=%22MAPZEN%22#custom-script

[grixm]

Looks like there will soon be another calving on the SWT.
Images are ten days apart.

[Stephan]

SWT's tip has calved.

The tip of the South Western Tributary has calved at a length of about 1.500 m. The resultiung iceberg has split into two smaller ones (dotted orange lines).
They probably line up behind the other grounded icebergs (grounded icebergs are marked by a black "*").

See attached picture. North is up.
The second picture shows a larger area, the orange coloured square shows the area of the first picture.