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paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2550 on: September 28, 2020, 12:08:51 PM »
I modified the image of my previous post (2547), containing only the lines related to the main calvings, and replacing the front line on 20/09 with today's front line  ;)

click to zoom in

Image update: I had forgotten to change the date in the image
>:(
« Last Edit: September 28, 2020, 12:18:16 PM by paolo »

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2551 on: September 28, 2020, 12:41:04 PM »
And we even have a high-resolution image of P2's calving  8)

baking

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2552 on: September 28, 2020, 12:54:11 PM »
Here is the 6-day GIF of the calving.  High resolution, but low contrast.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2553 on: September 28, 2020, 03:26:04 PM »
A little analysis :
> Measurements: calved area 17km2, including 2.5km2 of ice mélages aggregated at P2 and that ,at the time of calving, detached from P2
> Ice Origin: Calved ice is part of the SIS ice aggregated at the upstream PIG.This ice, being part of the SSM, is thinner than the ice of the PIG and of the ice of T11.
This ice, being part of the SSM, is thinner than the ice of the PIG next door and the ice of T11
> Causes: the piles of icebergs between the SIS and the PIG that were pointing west/east and that contrasted with the advance of the PIG are probably the cause of the opening of the marginal rifts, and are therefore the main cause of the calving, but we must not forget the icebergs that were stuck downstream between the SIS and P2 and that pushed P2 northwards.  ;)

I, like everyone else, am looking forward to the first clear picture of Sentinel2 to discuss with you about what we can expect in the future.

Shared Humanity

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2554 on: September 28, 2020, 04:22:13 PM »
With the large rift both widening and lengthening, P2 does appear to be calving soon.
I am mightily surprised LOL, normally I predict something on this thread and the reality is the complete opposite.

Given we are just heading into the SH summer, can we expect more (larger) calvings?

Shared Humanity

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2555 on: September 28, 2020, 04:26:35 PM »
paolo - In that 6 day GIF, did the crevasse on the portion of the PIG that was butted up against P2 open up a bit?

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2556 on: September 28, 2020, 04:55:35 PM »
SH,
I can't confirm your impression, indeed the two images in the animation, posted by Baking, don't have quite the same brightness and contrast (look at the darker structures in the image).
What I can confirm is that the two rifts: cR1 (the rift that was next to P2) and smR2 (the rift upstream of P2) are active rifts: in the month before this calving they have regularly widened and extended (with moderation)
As for the links you assume between season and calving, there have been none in the past and there are none now. But the season could be interesting: continuation of small calvings at the NSM and SSM and preparation for extended rifts across the PIG that may lead to larger calvings in the future. As I said above, I am waiting for the first clear Sentinel2 image to make a more accurate forecast.

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2557 on: September 28, 2020, 06:05:06 PM »
Thanks paolo for all these updates. It seems to me that also parts of the damage zone have left together with the "P2 iceberg". I wonder whether a meta stable front in the damage zone can be established or whether further minor calvings further upstream are unavoidable in the next future.
It is too late just to be concerned about Climate Change

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2558 on: September 28, 2020, 06:28:56 PM »
Stephan,
I mentioned in my post the small icebergs of the DZ (Damage Zone) that were aggregated with P2 (I mention them as Ice mélange) and I evaluated them at 2.5km2.
Other calving’s in the SdDZ (Southern downstream Damages Zone) are inevitable, maybe the current front will last some ten days, but no more. And further upstream the structure of the icebergs of the DZ is less packed and the successive calving’s could be faster...
I became very pessimistic  :'(

Tor Bejnar

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2559 on: September 28, 2020, 07:25:18 PM »
I continue to be amazed by the expertise shown on a couple Antarctic glacier threads.  Quite impressive for an Arctic Sea Ice Forum!

Something I've learned these past few months:
Quote
As for ... links ... between season and calving, there have been none in the past and there are none now.
Arctic ice is healthy for children and other living things.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2560 on: September 28, 2020, 08:43:32 PM »
Clearly, I was speaking for the PIG, but for other ice platforms this link season/calving can clearly exist (action of melt water, see the classic example of the LarsenB; closer to the PIG, this may be the case in the future for the north side of the NIS).

Tor Bejnar

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2561 on: September 28, 2020, 09:21:46 PM »
Yes, Paolo, that quote was intended for PIG dynamics, specifically (without implications for other glaciers' seasonal or lack of seasonal behaviors).
Arctic ice is healthy for children and other living things.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2562 on: September 29, 2020, 11:23:00 AM »
Micro calving on the NSM side, small crisis of jealousy for his big brother.
The bay between the PIG and the Ice Rise Evan's Knoll is not only getting deeper, it's getting wider.
Animation based on low resolution images of yesterday and today.

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2563 on: September 29, 2020, 08:37:24 PM »
I am deeply concerned - will there be a month, or at least a week, without further (micro-/mini-)calvings at all? How long will this be going on?
It is too late just to be concerned about Climate Change

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2564 on: October 02, 2020, 01:42:47 PM »
Animation with the images of 26/09 and 02/10.

The iceberg A seems almost free and should calve soon.
Cork3c moves around a lot and its support is crumbling and, even if it is still linked to the SIS, it will soon be calving too.

Click to animate

added PS : and behind we don't see great resistance to calving, emptying of the DZ to be expected
« Last Edit: October 02, 2020, 01:49:17 PM by paolo »

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2565 on: October 02, 2020, 02:34:11 PM »
And animation on the NSM side, still with the images of 26/09 and 02/10.
No news, calving on the PIG side having already been communicated on 29/09. We can still note that the Ice Rise Evan's Knoll side rifts seem to widen.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2566 on: October 07, 2020, 03:54:47 PM »
As expected the last piece of the Cork3 calved with other icebergs behind (indicated with a star).
Animation based on the images of 01/10 and 07/10.

Click to animate

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2567 on: October 07, 2020, 11:26:05 PM »
I take advantage of the fact that the Sentinel2 image of 21/09, which partially covers SWT, was clear to present some considerations on the DZ of SWT:

In the good old days, the PIG forced the SWT to rotate 120° around an Ice Rise and its left part was pushed against this Ice Rise. Sometimes, after the PIG (and the SWT) calving’s, the pressure was temporarily lacking and it could open locally some gaps between the SWT and the Ice Rise, but these openings were without tomorrow and the SWT then approached again to the Ice Rise => no DZ

Now no more PIG, the right side of the SWT has retreated a lot and now its movement is towards the North and tends to straighten up later on by powering up the SIS. In conclusion the left part is completely free, its movement is no longer parallel to the Ice Rise and the SWT is moving away from the Ice Rise => Opening a DZ
And already the Ice Rise it takes advantage of it to expand...

Since the speed with which the SWT moves away from the Ice Rise is maximum upstream, the DZ has started to open upstream to then extend downstream and soon it will be open to the sea. In this case the emptying will be slowed down by the fact that there is an Ice Rumple under the final part of the SWT (for this reason here the icebergs, once calved, wait a long time before moving away definitively), but the complete separation between the SWT and the eastern part of the Ice Rise can be considered as definitive.  In the same way it seems to me that the loss of the pinning point provided by the Ice Rumple with a front, for the SWT, further upstream is inevitable.
I find that we are witnessing a complete dismantling of the PIIS and that it proceeds quickly, too quickly...

You will find three animations:
The first one, very large to give an idea of the whole, contains the images spread out between the 21/10/2016 and the 21/09/2020 an image approximately every 6 months.
The other two limited to the period between 02/03/2019 and 21/09/2020 present two zooms on the DZ: one for the upstream part and the other for the downstream part.

Large images, click to animate


Added: SWT image with notations
« Last Edit: October 07, 2020, 11:46:37 PM by paolo »

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2568 on: October 08, 2020, 05:42:53 PM »
A small iceberg has calved on the SWT side (in the animation is identified by an arrow relative to its movement after calving)
This is the opportunity, while waiting for a Sentinel2 image, to present and name the multitude of marginal rifts caused by the shear between the SWT and the SIS. Remarkable is the EmR3 rift which opened recently and expanded rapidly.

It is also interesting to notice that now the SWT flow opens in a fan shape, the right side having a NE direction and the left side a N direction.  This being the cause of the (recent) opening of a longitudinal rift.

Conclusion: we can expect, in the next few months, a crumbling of the right side of the SWT.

Finally it is also interesting to notice the transversal rift that opened in the left part  (see the last image of the previous post)..

The animation uses the images of yesterday and today.

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2569 on: October 08, 2020, 07:12:44 PM »
Thank you paolo for the SWT update.

I also mentioned the "ZoD" and its growth, now better called "DZ", in the western part of the SWT, close to the ice rise, in a posting last melting season.
I share your opinion of a structural change of the SWT, due to the missing buttressing by PIIS-MIS. I guess that the greater instability is now in the eastern part of SWT, which should see further (minor) calvings soon. With further calvings the whole SWT will move faster, and more areas will come closer to the calving front. This front will move westward and may finally reach the DZ. Until then a complete decoupling of the ice masses of the ice rise and the SWT will be completed.

No good news at all...
It is too late just to be concerned about Climate Change

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2570 on: October 10, 2020, 12:45:22 AM »
The Sentinel2 images were not very good, but they show more details than the Sentinel1 images.

SSM: one can notice the complete fracture in the ice mélange of the SdDZ, it is parallel to the movement of the PIG and therefore there will be no resistance neither to the emptying of the DZ nor to the movement of the PIG. Consequently the rifts cR1 and smR2 should not change too much at the moment.
It will be to be followed, further upstream :
> if the last PIG/SIS shear point, currently upstream of A, will hold and for how long.
> the evolution of the SIS piece, noted A in the image, and see if it will detach from the SIS and if it will cross over, creating a point of resistence,
> if marginal rifts will open in the PIG in front of and upstream of A.

NSM: here again, it will be necessary to follow the last PIG/NE-IS shear point upstream of nmR1 and, downstream, the evolution of rifts in the NE-IS in front of the Ice Rise Evan's Knoll.

SWT: Another iceberg seems to be completely detached from the SWT and shows the state of decay of this part.

Click to zoom in

gerontocrat

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2571 on: October 14, 2020, 01:15:28 PM »
An arcticle in Yale climate connections - https://yaleclimateconnections.org/2020/10/bleak-views-of-melting-antarctic-ice-from-above-and-below/ with links to visulas on PIG and Thwaites,

e.g. The ice front at Pine Island Glacier in a more or less stable position from 1973 to 2014, and then a startling retreat in 2015 through the present. Roughly 30% of the ice shelf disappeared over the past six years.



"Para a Causa do Povo a Luta Continua!"
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paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2572 on: October 15, 2020, 09:47:09 PM »
I had judged the Sentinel2 image of 12/10 unusable because of its poor quality (see the first image), but I was wrong, it can be used.

Here is a first example with the SIS and its marginal fractures generated by the SWT action (second image). It shows that the WmR4 ([SIS] west marginal rift N°4), which we had seen appearing recently in the Sentinel1 images, and whose beginning, on the SWT side, appeared in an unmistakable and indisputable way only in the last images, is now very extended (more than 10km).

It seems that the part of the SIS related to T11, whose front is no longer constrained by the PIG, and which suffers on the flanks from the actions of the SWT and the PIG, has become unstable and that we may see it crumbling in the near future.

I also added, for comparison, yesterday's Sentinel1 image of this part of the SIS (third image; I noted on this image the probable extension of this rift), as well as the Sentinel2 image of 16/03 (fourth image) to give an overall view of T11 (note the two ices rumples that delimit it to the east and west).

  Apart from the first image the others are large and you have to click on them to zoom in.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2573 on: October 15, 2020, 10:11:27 PM »
As second example of use of the Sentinel2 image of 12/10 I propose you the report on the current extension of the rifts cR1 and SmR2:
The first image gives an overview of these two rifts and I indicate the extension observed, see on this subject the two other images which are zooms on their terminal point. In the last few months they have extended and widened, but there is nothing catastrophic (at least for the moment).

On the other hand, I've been looking for other central rifts further north, but there don't seem to be any. However, the poor quality of the image doesn't allow me to make a decision, even if I'm beginning to think that the possible rifts seen in the Sentinel1 images don't exist (for the moment).

click to zoom in

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2574 on: October 18, 2020, 11:00:34 PM »
I was looking for a good compromise to present the history (size and readability) and I think I found it. This is the result for the NSM. This is the history from 17/02 to 14/10, one front line every 12 days (NB the Sentinel1 images from 29/02 and 03/08 are missing)

If the result suits you it could become a regular post (every 12 days and with the SSM).

Click to animate

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2575 on: October 19, 2020, 12:21:21 PM »
As promised I am posting the history of the SSM in the new format. I will post the next update (NSSM and SSM) on 26/10 or the next day.

Fixed: My apologies, the order of the images was not good

Click to animate
« Last Edit: October 19, 2020, 12:30:04 PM by paolo »

oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2576 on: October 19, 2020, 12:37:21 PM »
Thank you paolo.
A bit of feedback - make the satellite images at the end stay longer, and the last image much longer, so the viewer can understand the visual summary of what happened.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2577 on: October 19, 2020, 01:28:03 PM »
Thank you Oren,
Here is the new version (NSM and SSM) with the suggested improvements

Click to animate

oren

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2578 on: October 19, 2020, 03:33:51 PM »
Thanks again paolo. Perfect.

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2579 on: October 19, 2020, 07:18:01 PM »
Thank you paolo. Perfect.
In addition (I hope this isn't too much work) a short history of the evolution of the largest cracks within PIIS, SIS or SWT in the same manner would be great.
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baking

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2580 on: October 26, 2020, 12:50:40 PM »
Minor calving at the Northern Shear Margin in today's 6-day high-resolution GIF.

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2581 on: October 26, 2020, 05:37:02 PM »
Also a small piece of the NIS (lower left corner of the image) has calved.
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paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2582 on: November 01, 2020, 09:38:33 PM »
New Sentinel2 image, still clouds, but a a beautiful image of the SSM (SdDZ) and of the cR1 (not news compared to Sentinel1 images)

Scale at the bottom left of SdDZ image

Click to enlarge images

baking

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2583 on: November 07, 2020, 06:15:59 PM »
As we get into November we begin to see seasonal effects creep in.  In the Northern Shear Margin a polynya which had formed recently off the Northern Ice Shelf shifted, or alternatively the melange in the NSM shifted forming a polynya in the NSM.  In any case, this marks the start of a new summer season.  No sign of any significant change in the sea ice at the southern margin yet.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2584 on: November 09, 2020, 12:41:09 PM »
NSM
This year has been remarkable, in fact currently not only is the sea at the front not free, but there is no polynya, neither at the SSM, nor at the center, nor at the NSM.
I tried to make a small statistic of the state at the end of October from 2000 to 2020 based on the images of Worldview and I find :
> that the sea was completely free in a majority of the years: 2001, 2002, from 2008 to 2016 and 2019
> that apart from the year 2017, in which a major calving had just occurred and there was a narrow band of open sea between the PIG and the iceberg and for which one cannot thus establish the presence of polynyas, in all the other years there was always a polynya in the SSM and often a polynya in the NSM and/or in the center.
I recall that these polynyas are generated by the warmer water currents coming out below the ice shelf.
So, if the absence of open sea in front of the PIG is generated by the weather conditions of this southern spring, the absence of polynyas seems to indicate that the outgoing currents are weaker than usual (beyond the weather conditions) and therefore also the CDW is weaker than usual.
Before this end of October there were from time to time polynyas at the NSM and SSM, but very small and larger polynyas formed either in correspondence of the Ice Rise Evan's Knoll on the NIS side, or in correspondence of the SM (shear margin) between the SWT and the SIS, thus caused by outflows not related to the PIG.
I find this important and noteworthy.

Coming to what happened at the NSM on 07 and today I present an animation based on the images of 01, 06, 07 and 09 November (the images of 06 and 09 being at low resolution).
It can be noted that what happened on the 07th is a violent event which, among other things, moved the iceberg that I noted "A" by 2km and by turning it by 180° and apparently exploded the iceberg that I circled with red. The present debris was swept away, which produced a "polynya" effect, pushing it to invade the polynya in front of Evan's Knoll Ice Rise.  Needless to say, that day it was better not to be there. This calving did not correspond to the detachment of new pieces from the ice shelf, but interested the mix of icebergs that had formed at the NSM.
It seems that a new calving (still iceberg mixture) has just occurred (image of 09, to be confirmed with a better resolved image) which filled again the bay (no more open sea).

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2585 on: November 10, 2020, 11:17:17 AM »
The low resolution image is not the best, but we can visualize a new calving at SSM, crumbling of the point (P3) at mR2 correspondence.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2586 on: November 12, 2020, 09:50:03 AM »
Finally a beautiful Sentinel2 image, not real novelties, just the clarity and precision of the images.
I start with the SSM, North and South side, SIS and SWT.

Click to enlarge

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2587 on: November 12, 2020, 09:53:18 AM »
Finally, two more images: the cR1 and the NSM

Click to enlarge

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2588 on: November 12, 2020, 10:23:18 AM »
But we must not forget the two areas of damage, upstream : NuDZ and SuDZ.
Well that's a lot of pictures, but they were the first of the season and they were expected since a certain time.

Click to enlarge

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2589 on: November 12, 2020, 07:07:31 PM »
Thank you paolo for this important update.
To say it shortly: What a mess!
It is too late just to be concerned about Climate Change

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2590 on: November 13, 2020, 12:37:15 PM »
SSM: the calving scheduled in the Sentinel2 image comments has arrived tonight

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2591 on: November 13, 2020, 06:34:26 PM »
Almost no week without a minor calving since the large calving event in the beginning of 2020. Is this a part of a transition that leads PIG from calving large portions of ice every 3-5 years into a lot of minor calvings that seemingly do not end? Is the structural integrity of the MIS already too weak to withstand currents and forces?
It is too late just to be concerned about Climate Change

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2592 on: November 13, 2020, 10:19:16 PM »
Almost no week without a minor calving since the large calving event in the beginning of 2020. Is this a part of a transition that leads PIG from calving large portions of ice every 3-5 years into a lot of minor calvings that seemingly do not end? Is the structural integrity of the MIS already too weak to withstand currents and forces?
IMO all of the ice downstream of the zones of destruction is toast. At that point there is a restriction on width. It might slow down their or it might be so thick marine ice shelf instabilities play a role.

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2593 on: November 18, 2020, 03:57:37 PM »
I post an animation based on the SIS images of 06/11, 12/11 and 18/11 to show the rapid evolution of WmR4 (especially in the last 6 days).

Click to animate

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2594 on: November 18, 2020, 09:10:35 PM »
My apologies, I had forgotten Sentinel2...  ::)

> An image of the SSM/SIS/SWT with the latest state of the SSM and the extension of WmR4 (click to enlarge)

> An animation to show the evolution between 11/11 and 17/11, even taking into account that a part of WmR4 was partially hidden by clouds the evolution seems obvious to me (click to animate)

Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2595 on: November 18, 2020, 10:10:25 PM »
It is too late just to be concerned about Climate Change


Stephan

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2597 on: November 19, 2020, 06:11:20 PM »
Thank you paolo. That link helped a lot  :)
It is too late just to be concerned about Climate Change

paolo

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2598 on: November 21, 2020, 10:03:49 PM »
New high quality Sentinel2 image, I take this opportunity to show the rapid changes at the SIS and at the SSM (the SdDZ Damage Zone)

> animation based on the two images of 11/11 and 21/11 (10 days apart, homogeneous orbits), centred on the marginal rifts of the SIS. One can see the rapid changes not only in WmR4, but also in the other rifts, which will soon lead to calvings in this sector.

> animation based on the two images of 17/11 and 21/11 (4 days apart, the orbits are not homogeneous, but they show the speed of change), centred on the SSM and the SdDZ

Large images, click to animate

update: blocks B1, B2 and B3 move relative to the SIS (slightly)
« Last Edit: November 21, 2020, 10:09:51 PM by paolo »

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Re: Pine Island Glacier (PIG) Calving and Discussion
« Reply #2599 on: November 21, 2020, 10:34:54 PM »
I think it was interesting to see (and follow) the behaviour of the last point of contact between the PIG and the SIS. Its resistance will determine the progress upstream of the damage zone.
Animation based on the images of 11/11 and 21/11

Click to animate