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Author Topic: Antarctic Icebergs  (Read 34159 times)

blumenkraft

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Re: Antarctic Icebergs
« Reply #50 on: September 25, 2019, 10:08:07 PM »
New iceberg!

Big claving at Amery!

Further west we might lose A68-A to the ocean this year?

Click to play!

blumenkraft

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Re: Antarctic Icebergs
« Reply #51 on: October 01, 2019, 09:26:16 AM »
As reported in the Thwaites glacier thread, B22-A has moved a little.

This GIF is showing 21st vs 28th of September.

crandles

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Re: Antarctic Icebergs
« Reply #52 on: October 01, 2019, 11:13:58 AM »
https://www.bbc.co.uk/news/science-environment-49885450

Quote
The Amery Ice Shelf in Antarctica has just produced its biggest iceberg in more than 50 years.

The calved block covers 1,636 sq km in area - a little smaller than Scotland's Isle of Skye - and is called D28.



Oops better covered at https://forum.arctic-sea-ice.net/index.php/topic,2578.msg560 (The Amery Ice Shelf Thread)

blumenkraft

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Re: Antarctic Icebergs
« Reply #53 on: October 01, 2019, 11:19:08 AM »
Belongs here too, Crandles. :)

Stephan

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Re: Antarctic Icebergs
« Reply #54 on: October 01, 2019, 11:28:13 AM »
As reported in the Thwaites glacier thread, B22-A has moved a little.

This GIF is showing 21st vs 28th of September.
Thanks blumenkraft for this animation.
Interestingly, most of the floating smaller icebergs move synchronously to B-22-A. But some icebergs, mainly at the western edge are immobile and seem to be grounded. Will they act as barrier to prevent B-22-A from further moving westward?
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charles_oil

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Re: Antarctic Icebergs
« Reply #55 on: October 02, 2019, 10:06:10 AM »

blumenkraft

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Re: Antarctic Icebergs
« Reply #56 on: October 06, 2019, 09:20:07 AM »
Will they act as barrier to prevent B-22-A from further moving westward?

Welcome Stephan :)

I think they are getting crushed if they are in its way. They are so tiny and B-22-A is so huge.

blumenkraft

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Re: Antarctic Icebergs
« Reply #57 on: October 06, 2019, 09:21:37 AM »
A68-A made quite some way...

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #58 on: October 23, 2019, 09:06:57 PM »
Again, we have parts of A-68A imaged on two dates both showing in Sentinel-hub Playground.
A-68A moved about 8.2 km in 7 days.  The two triangular icebergs in the 'fast ice' appear to have moved about 8.4 km.  Has the ice island rotated anticlockwise a bit, too?
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blumenkraft

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Re: Antarctic Icebergs
« Reply #59 on: October 23, 2019, 09:31:21 PM »
Yep!

Stephan

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Re: Antarctic Icebergs
« Reply #60 on: October 27, 2019, 10:58:14 AM »
As reported in the Thwaites glacier thread, B22-A has moved a little.

I analysed the Sentinel pictures from Oct 03 and Oct 26, 2019.
B22-A moved around 300 m in NNW direction. This is a movement of 13m/day.
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #61 on: October 29, 2019, 03:43:55 PM »
13 m/day for B-22A and 650 m/day for A-68A (e.g., 28 km during recent 43 day period). Sentinel-hup Playground imagery [click to run 2-frame GIF]
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Stephan

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Re: Antarctic Icebergs
« Reply #62 on: October 29, 2019, 07:22:44 PM »
OK Tor, "your" berg is faster than "mine"  ;)
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #63 on: October 29, 2019, 08:00:10 PM »
Is this where I say "Nana-nana-boo-boo"? ::)  I'll admit to having never heard 'the rest of the taunt' that the link provides.  :-[  We only ever said "Nana-nana-boo-boo" to each other in games of chase when an attempt to catch failed.

But the race is on!  Should we check in every few months?  Are there other contestants?
 :)
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blumenkraft

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Re: Antarctic Icebergs
« Reply #64 on: October 29, 2019, 08:17:42 PM »
Guys, my berg is D-26. At the end, i might win! :P

grixm

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Re: Antarctic Icebergs
« Reply #65 on: October 30, 2019, 10:48:36 AM »
A68a is on the move. In the last week it has drifted around 10 km NNE.

blumenkraft

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Re: Antarctic Icebergs
« Reply #66 on: November 10, 2019, 05:00:53 PM »
Is it expected for such a huge iceberg to move just as fast as the sea ice surrounding it?

Click to play.

blumenkraft

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Re: Antarctic Icebergs
« Reply #67 on: November 12, 2019, 07:04:08 PM »
Another fine SAR shot came in today.

This is 07.11. vs. 12.11.

gerontocrat

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Re: Antarctic Icebergs
« Reply #68 on: November 12, 2019, 08:25:43 PM »
Is it expected for such a huge iceberg to move just as fast as the sea ice surrounding it?

Click to play.
I've forgotten what it's freeboard is. 20 metres? Wind speed at 25 metres always higher than at the surface. 180 metres below the water ? Effect of currents ?

Lots of inertia but once on its way vey slow to stop.
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"Damn, I wanted to see what happened next" (Epitaph)

baking

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Re: Antarctic Icebergs
« Reply #69 on: November 13, 2019, 12:41:14 AM »
It's moving about 88 meters per hour.  It is most likely pulling/pushing the sea ice with it.  If it became grounded, the sea ice might move faster.  But if there is no grounding, there is no reason for it to move slower or faster than the surrounding sea ice except for inertia (or waves in open water.)
« Last Edit: November 13, 2019, 12:50:54 AM by baking »

blumenkraft

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Re: Antarctic Icebergs
« Reply #70 on: November 19, 2019, 04:54:55 PM »
Still having the impression it moves at sea ice speed (ish?). I was Gerontocrat on this one. I expected different outcomes with different forces affecting it. But this assumption might be wrong. There must be one dominant driving force which is ... what?

Anyway, it now moves away from the shallow waters. This is 12. vs. 18. Nov.

gerontocrat

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Re: Antarctic Icebergs
« Reply #71 on: November 19, 2019, 05:55:27 PM »
Still having the impression it moves at sea ice speed (ish?). I was Gerontocrat on this one. I expected different outcomes with different forces affecting it. But this assumption might be wrong. There must be one dominant driving force which is ... what?

Anyway, it now moves away from the shallow waters. This is 12. vs. 18. Nov.
Helluva big ice-breaker.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

blumenkraft

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Re: Antarctic Icebergs
« Reply #72 on: November 19, 2019, 07:22:03 PM »
Helluva big ice-breaker.

Nah, i would see that in the satellite pictures. ;)

gerontocrat

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Re: Antarctic Icebergs
« Reply #73 on: November 19, 2019, 07:31:43 PM »
Helluva big ice-breaker.

Nah, i would see that in the satellite pictures. ;)
Stealth technology (if the Klingons can do it, so can we).
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

blumenkraft

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Re: Antarctic Icebergs
« Reply #74 on: November 19, 2019, 08:09:20 PM »
Wow, this is uncanny. I just talked about Klingons with a friend.  :o

PS: Not in Klingon though.  ;D

blumenkraft

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Re: Antarctic Icebergs
« Reply #75 on: November 23, 2019, 05:52:54 PM »
4 beautiful cloud-free days in a row.

FredBear

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Re: Antarctic Icebergs
« Reply #76 on: November 30, 2019, 12:39:50 AM »
Looking back to the initial post I thought it might be interesting to have a current "fix" on all numbered icebergs so that future movements can be defined more accurately. This might be particularly useful for A23A and B22A which have been grounded for years but move slightly?

 The positions are at 11/29/2019

grixm

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Re: Antarctic Icebergs
« Reply #77 on: December 05, 2019, 08:05:01 PM »
Moved about 20 km since Nov. 23, no signs of slowing down

Stephan

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Re: Antarctic Icebergs
« Reply #78 on: December 05, 2019, 10:41:49 PM »
Are there any bumps or shallow waters on its way NE that would prevent iceberg A-68-A to continue its journey?
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baking

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Re: Antarctic Icebergs
« Reply #79 on: December 06, 2019, 03:50:09 PM »
Are there any bumps or shallow waters on its way NE that would prevent iceberg A-68-A to continue its journey?

Tierra del Fuego?  The Falklands?  A cruise ship?

blumenkraft

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Re: Antarctic Icebergs
« Reply #80 on: December 06, 2019, 04:40:58 PM »
LOL  ;D

Yes, Stephan, there are shallow waters ahead. But i think the ice island is tall enough to not get grounded there but snaking along as it does at the moment. We'll see i guess.




Tor Bejnar

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Re: Antarctic Icebergs
« Reply #81 on: December 16, 2019, 04:15:56 PM »
This Polar View image of A68-A (2019-12-16) shows some surface structure particularly well.  Some of the islands (made of rock) near the Antarctic Peninsula are labeled (and two bodies of water).  Joinville Island is the slightly boomerang-shaped island east ("above") the Antarctic Peninsula.  (This image is pretty much oriented so that NE is 'up' and NW to the left). The map just above shows there is shallow water (<250 m) between A68-A and Joinville Island.  [Place names from Wikipedia.]  -  Click for enlargement or go to link  (2019-12-16) for a much larger image.
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blumenkraft

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Re: Antarctic Icebergs
« Reply #82 on: December 16, 2019, 04:22:09 PM »
So what do you guys think about the thickness of this big boi?

Assuming it's >300m it will likely not get grounded, rather bouncing back from the underwater mountains, right?

If it's <250m, a grounding in the north is rather likely?

baking

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Re: Antarctic Icebergs
« Reply #83 on: December 16, 2019, 04:28:40 PM »
It's managed to bump into a couple of islands already without getting grounded, but if one end of it does get grounded I see it breaking up.  It's too long and unstable and too close to ocean currents to take the stress of being partially grounded.  But that's just my guess.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #84 on: December 16, 2019, 04:31:54 PM »
Quote
It measured 1,000 feet (300 metres) thick
per this article
or
Quote
1,100 feet thick [= 335 m]

per this article
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #85 on: December 16, 2019, 04:39:09 PM »
A68-A was grounded (apparently) for a while in September 2018, per discussion on the ASIF here.  It seems a piece broke off that was at the (or a major) pinning point.
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #86 on: December 16, 2019, 04:50:56 PM »
Picture of A68-A from a ship on 2019-12-09 (link to Wikipedia JPGs)
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blumenkraft

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Re: Antarctic Icebergs
« Reply #87 on: December 16, 2019, 04:51:59 PM »
Quote
It measured 1,000 feet (300 metres) thick
per this article
or
Quote
1,100 feet thick [= 335 m]

per this article

Amazing, Tor. Thanks so much!

blumenkraft

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Re: Antarctic Icebergs
« Reply #88 on: December 16, 2019, 05:07:13 PM »
A68-A was grounded (apparently)

Looks more like a bouncing against rocks to me.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #89 on: December 16, 2019, 06:51:28 PM »
B_,
Check out this contemporary comment re "pinned" (possibility) (and posts just above it).

For "bouncing off the rocks", look here.
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blumenkraft

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Re: Antarctic Icebergs
« Reply #90 on: December 16, 2019, 09:42:58 PM »
Haha, good find! Thanks for the hint, Tor.  ;)

baking

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Re: Antarctic Icebergs
« Reply #91 on: December 16, 2019, 11:53:06 PM »
First off, "pivots" are not necessarily due to grounding.  It is so large that currents pushing on one end could cause it to rotate just because the force would be so far away from the center of inertia.

Second, I was the first to say it "bounced" off the island, but it is more like a "skim."   But the point is that it didn't "hang" as it passed closely by the area so it was was not getting grounded in what might be relatively shallow water.

baking

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Re: Antarctic Icebergs
« Reply #92 on: December 17, 2019, 03:16:23 PM »
Yesterday's Sentinel-1 image of A68A shows a significant increase in speed.  The GIF below is in six day increments.

Also, I've drawn in the rough location of the shallows at the end of the Antarctic Peninsula.  There are two grounded icebergs circled in red.

Click first image to play GIF

baking

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Re: Antarctic Icebergs
« Reply #93 on: December 18, 2019, 04:51:07 PM »
Click below for a detailed GIF showing the approach of iceberg A68A over the last three days to a large number of grounded icebergs in the shallows off the end of the Antarctic Peninsula.  Two larger grounded iceberg can be seen in the upper left which were identified in the previous post, but on closer inspection there are many more smaller icebergs that are also grounded and are much closer to A68A.

Given the current speed and trajectory, A68A will hit the shallows in two days time.  Clearly, if these relatively tiny icebergs are grounded, A68A will certainly hit bottom if this motion continues.

blumenkraft

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Re: Antarctic Icebergs
« Reply #94 on: December 18, 2019, 04:57:21 PM »
We might see it pivot again. Another 180 makes it square, so to say.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #95 on: December 18, 2019, 05:42:22 PM »
Great GIF, Baking!  The rock under the grounded iceberg that is closest to A68-A has to be so shallow that the ice island will hit and bounce off of it (or split, or course), and not get stuck.  Going about due north (per Baking's GIF) though, A68-A is headed straight for it!

The map B_ posted on Dec. 6 indicates a 'deep current' just beyond these shallows.  Will the current drag A68-A to safety - off to the northeast (until the next islands, anyway)?

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blumenkraft

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Re: Antarctic Icebergs
« Reply #96 on: December 18, 2019, 09:17:53 PM »
First of all, sorry for the big file size.

Here is from 06.09 to today, 104 frames, daily increments, fast-playing to obscure the clouds.

oren

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Re: Antarctic Icebergs
« Reply #97 on: December 19, 2019, 01:59:19 AM »
baking and blumenkraft - love the GIFs.

baking

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Re: Antarctic Icebergs
« Reply #98 on: December 20, 2019, 05:10:27 AM »
I've added a couple more images to the GIF of A68A, roughly at 24 hour increments, the last just before midnight UTC.

Movement had been due North up until 24 hours ago when it shifted dramatically to the East, just short of the grounded smaller icebergs.

Is it just luck that it avoided grounding, or has it made contact with the sides of a much shallower rise and is sliding past?  And if it is sliding, will the irregular sides of the iceberg eventually get hung up?

Edit:  Also note the medium size berg (broken off from A68A) that has successfully maneuvered to the East of the grounded ice showing the shallow area is really quite small.
« Last Edit: December 20, 2019, 05:20:35 AM by baking »

blumenkraft

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Re: Antarctic Icebergs
« Reply #99 on: December 20, 2019, 08:29:38 AM »
The RAMMB is cloudy but it looks to me as if a tidal wave pushed it east. It lost a small piece at what's now the tale btw. I think here it hit the bottom.