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Author Topic: Pine Island Glacier (PIG) Calving and Discussion  (Read 419028 times)

baking

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Re: PIG has calved
« Reply #1700 on: February 10, 2020, 04:30:19 PM »
I have a thought experiment.  Any one can join in.  I'm trying to make it as neutral as possible.  There are no wrong answers, etc. etc.

There are three new cracks in the Pine Island Glacier today (excluding the unrelated stuff on the South West Tributary.)  I have named then Fred, George, and Sam in the image below.  What order did they happen in?

EDIT:  I have added a clearer detail of the cracks below without labels.
« Last Edit: February 10, 2020, 04:35:30 PM by baking »

paolo

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Re: PIG has calved
« Reply #1701 on: February 10, 2020, 04:34:40 PM »
I forgot about an NIS mini-calving.

blumenkraft

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Re: PIG has calved
« Reply #1702 on: February 10, 2020, 04:36:18 PM »
Yeah, i proposed to call them marginal rifts before but the idea was dismissed.

What can i say? They are there and they have to have a name for them if we want to talk about them, right?

Let's just call them MR1 and MR2 (as in marginal rift one and two).
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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blumenkraft

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Re: PIG has calved
« Reply #1703 on: February 10, 2020, 04:51:12 PM »
What order did they happen in?

I would say George, then Sam, then Fred. I can imagine some kind of shockwave going through the ice and it might propagate outside in. Just a guess. :)

Ah, also you have the highest leverage on George.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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baking

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Re: PIG has calved
« Reply #1704 on: February 10, 2020, 04:58:20 PM »
As long as we are naming things, I just want to say that "The Point" will be the most vulnerable.

blumenkraft

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Re: PIG has calved
« Reply #1705 on: February 10, 2020, 05:08:00 PM »
Why do you think so, Baking? Because the icebergs floating out there?
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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baking

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Re: PIG has calved
« Reply #1706 on: February 10, 2020, 05:25:43 PM »
Why do you think so, Baking? Because the icebergs floating out there?
It will be exposed to water on two sides and the ice there is very thin.  I don't think the occasional iceberg bumping into it will matter much.

In general I expect more small calving on the Southern Margin and it will be a year or two before anything interesting happens in the North.  The next new transverse rift will be at a substantial angle to these old rifts.  As much as 45 degrees.

Shared Humanity

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Re: PIG has calved
« Reply #1707 on: February 10, 2020, 07:03:10 PM »
KiwiGriff,
Attached:
an animation of the PIG between 2003 and 2014

It is not a coincidence that calvings have been occurring where the PIG meets the southwest tributary.

Shared Humanity

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Re: PIG has calved
« Reply #1708 on: February 10, 2020, 07:13:09 PM »
Given the rubble of small icebergs along the side of PIG, I think PIG may have lost contact with the southwest tributary forever.

Stephan

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Re: PIG has calved
« Reply #1709 on: February 10, 2020, 07:19:15 PM »
As long as we are naming things, I just want to say that "The Point" will be the most vulnerable.
Let me have a closer look on "Cork II". I wonder how solid or vulnerable or already completely broken up its connection to the Point is (circled in green, picture taken from baking's post - thanks). This question is important for the fate of the icebergs in the zone of destruction (circled in yellow).
On the SW side Cork II seems to have a solid connection to the SIS, and it didn't seem to be affected by the latest calving.
It is too late just to be concerned about Climate Change

blumenkraft

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Re: PIG has calved
« Reply #1710 on: February 10, 2020, 07:27:50 PM »
My guess is that Cork II is pressed into the SWT and that it will stay there strongly until a biggish iceberg from upstream knocks it out.

So many new questions now...
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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Stephan

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Re: PIG has calved
« Reply #1711 on: February 10, 2020, 07:30:09 PM »
It is incredible, what has happened yesterday and today.
I want to thank all the contributors with their pictures, animations and explanations.
I am pretty sure that noone outside of this forum has followed the preparation of this major calving event with such an intensity as we have done it - together.

PS: In Germany in football there is a saying "Nach dem Spiel ist vor dem Spiel" - this saying can be easily transferred into "After calving is before (the next) calving".
It is too late just to be concerned about Climate Change

blumenkraft

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Re: PIG has calved
« Reply #1712 on: February 10, 2020, 07:35:59 PM »
... any moment now! ;)
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

Stephan

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Re: PIG has calved
« Reply #1713 on: February 10, 2020, 07:58:25 PM »
I tried to calculate the area of the latest major calving by using the instruments that EOSDIS offers. I ended up with around 360 km² in several attempts. This is quite huge, and at least comparable to the calvings of 2016, 2017, and 2018.

Edit: ASLR writes about 312 km² in one of his postings today in the "Ice Apocalypse" thread.
« Last Edit: February 10, 2020, 10:33:26 PM by Stephan »
It is too late just to be concerned about Climate Change

paolo

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Re: PIG has calved
« Reply #1714 on: February 10, 2020, 08:04:35 PM »
Blumenkraft,
Concerning the residue of the upcoming calving: parts linked to the extensions R1, R2, and R3, parts that will surely calve (either very quickly: last piece of R1, or a little further for the others), but that cannot be considered as new calving and taking into account that everybody knows them, I propose to prefix it: exR1, exR2 and exR3. In clear one considers it as a regularization of the current calving, but certainly not a new calving.
NB: the case of R3 is particular, it is not clear if he has calved in its entirety or if there is an extension pending (to be followed).
I attach two zooms of exR1 and exR2

From two marginal rifts that opened very quickly, but that stopped after R3 opened, and that are surely to be followed, we can indeed name them mR1 and mR2.
It will be renamed R1, R2 if and when it will be the case.

For the moment I will avoid creating other names; indeed it is necessary to limit the naming only to the very next discussed cases and to use it sparingly to avoid any complication, possibility of confusion and even usefulness (if you have many names you don't know what they mean anymore).

Baking,
I'm all for "The point."

Stephan,
I would not tell much about Cork2, it seems structurally very weak and there is already a fracture at the base, if you blow it goes away

bluice

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Re: PIG has calved
« Reply #1715 on: February 10, 2020, 08:05:15 PM »
The MR1 and MR2 look like they are upto no good.

The King is dead, long live the King!

wdmn

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Re: PIG has calved
« Reply #1716 on: February 10, 2020, 08:15:00 PM »
It is incredible, what has happened yesterday and today.
I want to thank all the contributors with their pictures, animations and explanations.
I am pretty sure that noone outside of this forum has followed the preparation of this major calving event with such an intensity as we have done it - together.

PS: In Germany in football there is a saying "Nach dem Spiel ist vor dem Spiel" - this saying can be easily transferred into "After calving is before (the next) calving".
+1

Thanks guys for the fantastic work in this thread.

paolo

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Re: PIG has calved
« Reply #1717 on: February 10, 2020, 08:22:35 PM »
Baking,
In fact, they say almost the same thing:
Me: the iceberg was in tension: compression and torsion, practically a bomb ready to explode. The release of the SW end triggered the whole thing.
You: the iceberg was in tension: compression and torsion (practically a bomb ready to explode). Releasing the NE end triggered the whole thing.
We differ only for the trigger, which doesn't seem very important to me.
We have no other means of analysis than satellite images and I know that I won't convince you and you won't convince me.
Maybe I'm wrong, maybe I'm right, but I consider that discussing it again would be a waste of time for both of us and our time is precious, there are so many things to say in this forum. ;)

sidd

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Re: PIG has calved
« Reply #1718 on: February 10, 2020, 11:48:22 PM »
The 100m limit for ice cliff instability is for ice at maximum strength. In the real world, ice in glaciers is fractured, twisted, has cracks and imperfections. So may not be ncessary to hit 100m freeboard (above waterline) to collapse. But looking at Jacobshawn suggests 100m is a good ballpark.

sidd

baking

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Re: PIG has calved
« Reply #1719 on: February 11, 2020, 01:13:38 AM »
Baking,
In fact, they say almost the same thing:
No.  The two attaching points I was referring to were both on the Northern side.  The cracks traveled down one side of a "U" and back up the other.  We can agree to disagree, but don't misrepresent what I said.


Tor Bejnar

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Re: PIG has calved
« Reply #1721 on: February 11, 2020, 03:09:44 AM »
Fabulous, J Cartmill!
Arctic ice is healthy for children and other living things.

blumenkraft

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Re: PIG has calved
« Reply #1722 on: February 11, 2020, 09:10:07 AM »
Recap GIF!
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

blumenkraft

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Re: PIG has calved
« Reply #1723 on: February 11, 2020, 09:17:48 AM »
Cork zoom.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

blumenkraft

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Re: PIG has calved
« Reply #1724 on: February 11, 2020, 09:27:57 AM »
Fred, George, and Sam in the image below.  What order did they happen in?

I'm changing my opinion. I'm now thinking Sam was first.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

blumenkraft

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Re: PIG has calved
« Reply #1725 on: February 11, 2020, 10:47:03 AM »
Here are two GIFs from RAMMB to give you an impression of the drifting speed.

Looks like the SWT iceberg will get crushed by the big boi.

The first one I1 band. This band is higher resolution but delivers fewer frames per time period.

The second one is D&N band, lower resolution, but more frames.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

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blumenkraft

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Re: PIG has calved
« Reply #1727 on: February 11, 2020, 12:00:36 PM »
No mention of the ASIF :(

Fucking idiots!
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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Re: PIG has calved
« Reply #1728 on: February 11, 2020, 12:22:04 PM »
Fucking idiots!

That's one way of putting it BK! If I hadn't been preoccupied with Roger Pielke Jr.'s meltdown I might have tweeted sooner.

As it is the WaPo have gone with a Copernicus tweet that was only a day and a bit late. They could at least have used Bert Wouters' animation, which beat "Snow White" to the punch on the 9th.

P.S. https://twitter.com/GreatWhiteCon/status/1227192922593992704
« Last Edit: February 11, 2020, 12:30:09 PM by Jim Hunt »
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

bairgon

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Re: PIG has calved
« Reply #1729 on: February 11, 2020, 01:37:18 PM »
Cork zoom.

Observations:
 - some large bits of the SW tributary have broken off as well, letting the cork float free.
 - the "melange" hasn't moved. Is it stuck in place via sea ice?

blumenkraft

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Re: PIG has calved
« Reply #1730 on: February 11, 2020, 01:43:17 PM »
- the "melange" hasn't moved. Is it stuck in place via sea ice?

I guess we have to wait for the Sentinel 2 shots to see what's going on there. Not sure if we get cloud-free ones today though. :(

I'm guessing it's only a matter of days before we see the open ocean there.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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bluice

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Re: PIG has calved
« Reply #1731 on: February 11, 2020, 02:26:30 PM »
Open water “wedge” between PIIS and SW tributary would probably be bad news for the longer term stability of PIIS

blumenkraft

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Re: PIG has calved
« Reply #1732 on: February 11, 2020, 02:37:06 PM »
Yes, that's what i think too.

And for how i see it, no one here thinks differently on that one.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

bluice

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Re: PIG has calved
« Reply #1733 on: February 11, 2020, 02:51:11 PM »
Probably not, I’m just thinking aloud, so to say.

Timeline is interesting though. I have a funny feeling we don’t have to wait years until the next calving.

paolo

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Re: PIG has calved
« Reply #1734 on: February 11, 2020, 04:23:47 PM »
If the Sentinel2 image has the same quality (knotting coverage) of Terra/Modis we are not spoilt. >:(
Let's hope to have at least two good images (and if possible coherent: multiple interval of 10d) after calving before the summer blackout (summer for us ;))

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Re: PIG has calved
« Reply #1735 on: February 11, 2020, 04:30:07 PM »
Today's Sentinel 3 has clouds as well. :(

There is weather coming from the east.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

FrostKing70

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Re: PIG has calved
« Reply #1736 on: February 11, 2020, 04:56:50 PM »
Does anyone have access to a map or GIF showing the calving events since ~2000?  I find those to be useful to see the retreat over a longer period of time....

FrostKing70

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Re: PIG has calved
« Reply #1737 on: February 11, 2020, 04:58:21 PM »
I should have done a search before posting!

https://earthobservatory.nasa.gov/features/pine-island

baking

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Re: PIG has calved
« Reply #1738 on: February 11, 2020, 05:10:39 PM »
Fred, George, and Sam in the image below.  What order did they happen in?

I'm changing my opinion. I'm now thinking Sam was first.
And to think I was so proud of you! :-\
You were right the first time.  George was first because the release of energy caused the huge separation.  Sam was an immediate shattter from the explosive force of George but there was no built up tension to cause any kind of reaction so not much separation.

Fred was last because the ice was moving to the SW and the Southern end got caught up in the melange so it sheared in two with that weird shallow diagonal fracture and the the Northern piece(s) kept sliding past along the fracture.

Sure part of Sam was present earlier, but I assume most fractures have preexisting starting points.  I was talking more about the explosive energy release of a calving event.

On a not unrelated note, notice how the Northern pieces of the main calving event continue to move parallel to the front while the Southern pieces are still rotating clockwise.  The amount of energy required to put huge pieces of ice like these into motion is not trivial and there has to be explanation for why they move the way they do.  I think it is evidence that the Southern ice was hit with a secondary event that pushed it away from the front and my main suspect is the ice that broke up between R1 and R2.

I could go on, but I am not an expert and this is all my own speculation.  I'm just trying to encourage people here to think about how calving events occur and "reading the ice."

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Re: PIG has calved
« Reply #1739 on: February 11, 2020, 05:23:27 PM »
:)

Don't you think the GIF shows differently, Baking?

That initial right angle crack, that's Sam.
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

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baking

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Re: PIG has calved
« Reply #1740 on: February 11, 2020, 05:33:30 PM »
:)

Don't you think the GIF shows differently, Baking?

That initial right angle crack, that's Sam.
I've seen the GIF.  I'm not talking about cracks.  I'm talking about calving.  If you look at your nice Recap GIF from Post #1722 you can see the crack in the main front that becomes part of that odd zig-zag fracture.  It doesn't mean that the preexisting crack caused anything other than the shape of the end result.

EDIT: Cracks shape the calving events, they don't cause them.

paolo

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Re: PIG has calved
« Reply #1741 on: February 11, 2020, 05:34:45 PM »
Baking,
Outside of your game, I'm reading the ice, but I have another reading.
I accept the fact that there may be other readings and for the moment I don't see any elements that could make a definitive decision.
These different readings need to be taken into account, I do, but, although I hope so, I doubt you do (I hope you'll forgive me if I'm wrong about you).

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Re: PIG has calved
« Reply #1742 on: February 11, 2020, 05:35:27 PM »
I have to think about this.  ;)
“I’m an introvert. I’m just different that’s all. I’m so sorry. I don’t have a gun. I don’t do that stuff... All I was trying to do was to become better. I’ll do it... You all are phenomenal. You are beautiful. And I love you. Try to forgive me. I’m sorry.”

Elijah McClain

baking

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Re: PIG has calved
« Reply #1743 on: February 11, 2020, 05:43:15 PM »
These different readings need to be taken into account
All I'm trying to do is start a discussion.  We spend a lot of time here looking at pictures and making predictions, but when these very rare events happen do we look back and say what did we get right and what did we get wrong?

EDIT: And I will clearly grant that you had the best prediction for the timing of this calving event.

paolo

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Re: PIG has calved
« Reply #1744 on: February 11, 2020, 06:31:07 PM »
Doubting that the Sentinel1 image is good I created an image with the first analyses of the calving on the north side based on the last quality Sentinel2 image (01/02) and taking into account the last high resolution Sentinel1 image of today.
Explanation: I use the MIS notation (Main Ice Shelf) for the part of the PIIS fed directly by the PIG.
Explanation: I use the NE-IS notation for the small part of the NIS that has remained in contact with the MIS and that is now limited to a narrow strip next to the ice rises "Evans Knoll" and a small ice shelf further upstream.

In the attached picture there is only the narrow band of the NE-IS. The ice of the NE-IS is largely supplied by ice from the ice shelf further upstream, which is deformed and driven by the MIS. It is also supplied by the ice rises, but this contribution is minimal and mostly almost static (once destroyed it is definitively over).
For the future it must be taken into account that the rapid movement of the MIS will tend to break the NE-IS downstream and therefore a zone of mini calving north of the shear margin is to be expected. Furthermore, the extension of the old rifts and especially of R2 will have to be followed.
And it should not be forgotten that, unlike 5 years ago, there are no longer any underwater pinning points.
The complex framework is not good, but could have been worse (little consolation).  :(

KiwiGriff

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Re: PIG has calved
« Reply #1745 on: February 11, 2020, 07:07:19 PM »
Quote
The amount of energy required to put huge pieces of ice like these into motion is not trivial and there has to be explanation for why they move the way they do.
The only way you are going to get such movement is by currents in the underlying water .
Stick a 9/10 submerged bucket in a pond  and try moving it with a force . Any energy supplied by the bergs being under tension is going to be quickly dissipated by the volume of water you have to displace to move such an object relative to the water it is submerged in. Wind is not going to move them that much either .  I suggest the underlying currents are also responsible for the forces required for calving the ice off to start with.
« Last Edit: February 11, 2020, 07:12:50 PM by KiwiGriff »

baking

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Re: PIG has calved
« Reply #1746 on: February 11, 2020, 07:17:01 PM »
Quote
The amount of energy required to put huge pieces of ice like these into motion is not trivial and there has to be explanation for why they move the way they do.
The only way you are going to get such movement is by currents in the underlying water .
Stick a 9/10 submerged bucket in a pond  and try moving it with a force . Any energy supplied by the bergs being under tension is going to be quickly dissipated by the volume of water you have to displace to move such an object retaliative to the water it is submerged in. Wind is not going to move them that much either .  I suggest the underlying currents are also responsible for the forces required for calving the ice off to start with.
Now put the bucket of water in a bathtub and try the same experiment.  The relative size of the ice to the water it needs to displace is significant.

vox_mundi

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“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

RoxTheGeologist

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Re: PIG has calved
« Reply #1748 on: February 11, 2020, 07:26:06 PM »
Yes, that's what i think too.

And for how i see it, no one here thinks differently on that one.

It's going to be interesting to see if that whole 'wedge' of fractured ice clears out and we get calving along that face from both the PIG and the Ice sheet.


Stephan

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Re: PIG has calved
« Reply #1749 on: February 11, 2020, 07:31:11 PM »
Thank you vox mundi for sharing the esa video with us.
What surprised me is the new sharp edge that has been produced on the SWT. It doesn't look very stable - IMO a further calving, possibly even up to the "nose" (pinning point) seems to be likely in the future.
It is too late just to be concerned about Climate Change