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Author Topic: Antarctic Icebergs  (Read 38105 times)

blumenkraft

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Re: Antarctic Icebergs
« Reply #300 on: June 27, 2020, 05:50:31 PM »
So what's the name of the new one? A69?

Here is the progress A68A and A68C made. The sea ice is catching up again. Click to play.

blumenkraft

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Re: Antarctic Icebergs
« Reply #301 on: July 04, 2020, 07:07:59 PM »
A68A update.

Note how the sea ice totally caught up with the iceburg. A68C made a good way south north-west.
« Last Edit: July 05, 2020, 06:17:42 AM by blumenkraft »

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Re: Antarctic Icebergs
« Reply #302 on: July 05, 2020, 12:56:59 AM »
A68A looks like it moved back a bit. Maybe it is still interacting with that ridge.

FredBear

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Re: Antarctic Icebergs
« Reply #303 on: July 05, 2020, 04:01:23 AM »
From the locations of the icebergs A68C has moved 1° north in a week, 32' east as well,
but A68A has moved 2' south, 8' east in the same time (to 03 July).
Location of A68C is almost 2° north, 3° east of A68A now.


https://www.natice.noaa.gov/pub/icebergs/Iceberg_Tabular.pdf
« Last Edit: July 05, 2020, 04:12:27 AM by FredBear »

blumenkraft

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Re: Antarctic Icebergs
« Reply #304 on: July 05, 2020, 06:18:15 AM »
North! Of course. Thanks, Fred. Corrected my post.

blumenkraft

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Re: Antarctic Icebergs
« Reply #305 on: July 05, 2020, 06:26:04 AM »
A68A looks like it moved back a bit. Maybe it is still interacting with that ridge.

I have no doubt it is somehow interconnected with it through ocean currents. Not directly over it at the moment though.

blumenkraft

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Re: Antarctic Icebergs
« Reply #306 on: July 13, 2020, 07:36:42 PM »
Ladies and gentlemen, the wonder of birth. Meet A68D.

igs

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Re: Antarctic Icebergs
« Reply #307 on: July 13, 2020, 08:43:46 PM »
Ladies and gentlemen, the wonder of birth. Meet A68D.

From size it looks more like an abortion [JK]

 ;) ;) ;) ;) ;)

 :D :D :D :D :D

blumenkraft

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Re: Antarctic Icebergs
« Reply #308 on: July 13, 2020, 09:13:24 PM »
Well, it's kilometers long, hundreds of meters thick, and kinda heavy. ;)

igs

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Re: Antarctic Icebergs
« Reply #309 on: July 13, 2020, 10:07:36 PM »
Well, it's kilometers long, hundreds of meters thick, and kinda heavy. ;)

[JK] means Just Kidding, i thought with all the smilies & smirks it was clear, sorry.

Further just for the sake of it, size of children we see in relation to the size of the parents.

 ;D ;D ;D

My wife calls this kind of kidding [Half Jokes] because a part is true but taken with a good portion of humor just to make fun.

blumenkraft

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Re: Antarctic Icebergs
« Reply #310 on: July 13, 2020, 10:14:21 PM »
All good, IGS. No need to be sorry, i was joking as well. Mine was one-tenth of a joke, not even half! ;)

FredBear

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Re: Antarctic Icebergs
« Reply #311 on: July 22, 2020, 02:10:58 AM »
       
5 week updated positions given for a couple of moving icebergs of current interest:-
Locations @ 02/28/2020:-     ->08/05/2020              ->12/06/2020           ->17/07/2020
A68A    62°37'S    53°14'W.  ->60°32'S    50°21'W    -> 59°57'S 48°55'W  ->59°30'S 49°13'W
A68C                 (22/05/2020   -> 59°57'S 48°55'W) -> 59°26'S 47°21'W  -> 57°41'S 41°12'W
D28      67°18'S    72°12'E.   ->66°22'S    71°12'E.   ->66°40'S  64°41'E    ->66°35'S  59°59'E

A68A moving more slowly recently (still 0.5° north in 5 weeks, but little in last 4 weeks), A68C is smaller and moved around much more since it broke off, more easterly recently.
D28 has continued moving westward relatively rapidly round the coast (at last!) - probably rotating(?).

arctic io pictures have disappeared for me so I am now working blind - anyone know how to get those lovely historical records back?


Source:-     https://www.natice.noaa.gov/pub/icebergs/Iceberg_Tabular.pdf

blumenkraft

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Re: Antarctic Icebergs
« Reply #312 on: August 16, 2020, 05:28:10 PM »
Nice, A68-A coming into sight of Sentinel 3 soon!

grixm

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Re: Antarctic Icebergs
« Reply #313 on: September 02, 2020, 10:35:10 PM »
A68-A twirling around in the same spot for the last month and a half.

Tealight

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Re: Antarctic Icebergs
« Reply #314 on: September 08, 2020, 12:31:07 PM »
Iceberg A23A has moved significantly over the winter and is not classified as grounded anymore by the National Ice Center. According to their iceberg tables it happened in Week 28 (between 3rd and 10th July). However since then it hasn't moved much.
« Last Edit: September 08, 2020, 10:33:31 PM by Tealight »

FredBear

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Re: Antarctic Icebergs
« Reply #315 on: September 09, 2020, 03:00:39 PM »
Looked at the locations of two big "grounded" icebergs - they "wriggle" occasionally but have not moved far over many years, unlikely to have floated free yet?

Brunt ice shelf accumulates significant snow on the surface each winter, I don't know whether the "nearby" A23A does too as that could reduce its chances of floating free? Many other icebergs to the south have drifted west and then north over the years but A23A may be towards the centre of the circulation in the Weddell Sea?

There has been more icebergs break off the edges of B22A over the years and it looks more likely to move out and break up than A23A.

The other big 'berg is the grounded D15A which hasn't moved location in this time frame.

Locations @ 29/11/2019:-     ->14/09/2020             
A23A    75°47'S    41°04'W    ->75°36'S    40°12'W   
B22A    73°59'S  109°13'W    -> 73°58'S 109°20'W
D15A                     66°39'S 81°55'E

Source:-     https://www.natice.noaa.gov/pub/icebergs/Iceberg_Tabular.pdf

Stephan

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Re: Antarctic Icebergs
« Reply #316 on: September 11, 2020, 09:38:41 PM »
The sun still does not shine at the South Pole, but Amundsen Sea is north and bright enough to allow EOSDIS to make new pictures.

So the first look I took was on my pet iceberg that has lost parts of its SW tip some months ago (details in the Thwaites Gl. thread).

I took the opportunity and evaluated the movement of B-22A between 15. Nov 2019 and 11. Sept 2020.
It moved slowly in NW direction (around 5 km). I checked different places and spots on this iceberg, measured the distance between the two dates and added them into the attached picture. As far as I evaluated there seems to be no turning around of the iceberg.
« Last Edit: September 11, 2020, 09:45:25 PM by Stephan »
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Stephan

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Re: Antarctic Icebergs
« Reply #317 on: September 12, 2020, 09:08:37 PM »
In addition to my post yesterday I examined the area between B-22 and Bear Peninsula which - even during winter - frequently shows open water (probably of polynya type). The last week saw an extension of open waters (orange arrows) into areas that were sea ice covered before.

In addition I discovered the western tip of B-22 that calved off B-22 some months ago. It lies grounded in shallow seas N of Bear Peninsula (circled in yellow). Size, position, shape and texture reveal that this is the "missing part". It might stay there for a while, I will watch it this melting season.

See attached picture.
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #318 on: September 14, 2020, 09:24:39 PM »
Somebody with the name u/b_lumencraft (now, where did I see a name sort of like that before?  ::) :o ;) ) has posted a couple Antarctic Iceberg-related items at  https://www.reddit.com/r/Fans_Of_Hans_Club


For the record, B_ wrote to me: "Reposts to ASIF are of course fine with me."
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Tealight

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Re: Antarctic Icebergs
« Reply #319 on: September 20, 2020, 12:30:44 AM »
This week A23A moved another 4km. Compared to it's 81km length and 74km width it's not far, but it's also not grounded. Eventually it will reach the deeper parts of the Weddell Gyre.

https://cryospherecomputing.tk/Icebergs

Stephan

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Re: Antarctic Icebergs
« Reply #320 on: September 21, 2020, 10:11:16 PM »
Some recent observations around my pet iceberg B-22 in EOSDIS.

One of the icebergs in the mélange S of B-22 trapped behind grounded icebergs (green) was pushed out by strong currents in WNW direction in the last ten days. It is circled in yellow. The NW movement of B-22 over winter maybe has opened a gate that allows further export of icebergs from the mélange into the polynya. We will see...

A rift in the sea ice has formed (marked in broken lines in black). It appeared much earlier than last year (approx. position broken grey lines) and it is approx. 3-6 km further south than previous year.

Open waters from the polynya slowly crawl in SE direction (blue arrows), but some other parts are newly covered by sea ice (red crosses) that were open ten days ago. It is still quite cold there (Climate Reanalyser says something about -15°C today).

It is a very volatile area and its shape changes within days. See attached picture.
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Stephan

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Re: Antarctic Icebergs
« Reply #321 on: October 05, 2020, 10:02:22 PM »
It looks like B-22 is losing further pieces.
I analysed the latest picture from Sentinel 2 and found a small soon-to-be breaking off iceberg at the Western edge of B-22, circled in orange. The latest calving is marked by a blue arrow. A much older calving (yellow arrow) is still hanging around, it is grounded.

I also detected a new rift (green line) starting in the SW corner and going almost to the centre of B-22. It was absent last year. Is this a first sign of a more fundamental disintegration of my pet iceberg?

See attached picture.
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Re: Antarctic Icebergs
« Reply #322 on: October 05, 2020, 11:36:49 PM »
It looks like B-22 is losing further pieces.
I analysed the latest picture from Sentinel 2 and found a small soon-to-be breaking off iceberg at the Western edge of B-22, circled in orange. The latest calving is marked by a blue arrow. A much older calving (yellow arrow) is still hanging around, it is grounded.

I also detected a new rift (green line) starting in the SW corner and going almost to the centre of B-22. It was absent last year. Is this a first sign of a more fundamental disintegration of my pet iceberg?

See attached picture.
It probably is getting ready to break up. If not it has moved a few km towards the ocean this winter. A warm current tends to show up on that end of the northern portion of the iceberg so I am expecting some more change this Antarctic melting season.

Tealight

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Re: Antarctic Icebergs
« Reply #323 on: October 12, 2020, 01:56:46 AM »
A68A drifts into sub-Antarctic waters. Over the last week its speed was 15km per day northwards.

The northern tip (56.6S,48W) already touches 2-3°C warm edge currents. Maybe this is its last summer as a giant iceberg.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #324 on: October 12, 2020, 05:03:07 AM »
I'm curious, Tealight, why the ice island appears to be so close to the ice edge, or whatever that is 'below' the berg's point.

Below, I've rotated and annotated the Polar View image-selection screen (selecting a date range to identify only three images - October 9, 2020).  This shows the location and approximate shape of A68-A.  (I moved the scale [It didn't originally cross 30oW; it crossed 50oS, west of Chile].) [click for clearer image]

I then copied the two Preview images that include A68-A (its actual shape), stitched them together (keeping most of the southern image's area, and not perfectly done), annotated it and rotated it to approximate north being up.
« Last Edit: October 12, 2020, 05:13:23 AM by Tor Bejnar »
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APMartie2

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Re: Antarctic Icebergs
« Reply #325 on: October 13, 2020, 01:05:33 AM »
Really nice graphic Tor. I like seeing the big picture portrayal of A68-A out there adrift and its size in relation to S. Georgia Is.

I am a total ASIF lurker. This is one of my favorite sub-forums.

Tealight

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Re: Antarctic Icebergs
« Reply #326 on: October 14, 2020, 02:12:57 AM »
I'm curious, Tealight, why the ice island appears to be so close to the ice edge, or whatever that is 'below' the berg's point.

The island, South Orkney as you correctly identified is simply close to the polar front. The warm pacific waters have to squeeze through the drake passage and mix with the cold Antarctic water at that boundary.

Here is a graphic from wikipedia (Drake Passage article)

Stephan

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Re: Antarctic Icebergs
« Reply #327 on: November 02, 2020, 10:45:41 PM »
Update from my pet iceberg (B-22) in the Amundsen Sea, NW of Thwaites Glacier.

Finally a relatively clear day allowed another inspection of its NW movement. I took Sep 16, 2020 as reference day. Since then B-22 moved around 2 km into NW direction (black arrow).
This movement direction does not open the gateway for the sea ice south of B-22 at the moment. But if this movement will continue for another 13-15 km then the bottleneck (green lines between B-22 and the sea ice as well as between the sea ice and the fast ice south of it) will finally open.
At the moment the gateway is blocked by several grounded smaller icebergs (orange squares).
When this blocking is ended, the flush of sea ice south of B-22 into the open sea will accelerate, which will have a destabilising effect on the fast ice NW of Thwaites ice tongue.

See attached picture.
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baking

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Re: Antarctic Icebergs
« Reply #328 on: November 04, 2020, 05:20:52 AM »
https://www.bbc.com/news/science-environment-54798031

A68 iceberg on collision path with South Georgia

"The world's biggest iceberg, known as A68a, is bearing down on the British Overseas Territory of South Georgia.

The Antarctic ice giant is a similar size to the South Atlantic island, and there's a strong possibility the berg could now ground and anchor itself offshore of the wildlife haven.

If that happens, it poses a grave threat to local penguins and seals.

The animals' normal foraging routes could be blocked, preventing them from feeding their young properly."

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #329 on: November 04, 2020, 03:11:37 PM »
I'm reminded of Ernest Shackleton who, with 5 crew, sailed a 22.5' (6.9 m) lifeboat from Elephant Island to South Georgia Island after the sinking of the Endurance in 1915, "one of the greatest boat journeys ever accomplished". (Wikipedia offers a fascinating read.)  A-68A was just south of Elephant Island a while back, 1,300 kilometers southwest of South Georgia.


If A-68A does ground on or near South Georgia, it won't climb over the mountains like Shackleton did.  :P
« Last Edit: November 04, 2020, 03:20:32 PM by Tor Bejnar »
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #330 on: November 05, 2020, 03:10:21 PM »
PolarView offers some detail of the leading point as of November 4.

Per PolarView, the finger is about 20 km wide.
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Tealight

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Re: Antarctic Icebergs
« Reply #331 on: November 16, 2020, 04:12:06 PM »
It's been over two years since A68 calved from Larsen C. Even though it's length hasn't changed it lost a considerable amount of width in various places.

Here is an image with it's current size overlayed on an Sep 2018 image.


Tor Bejnar

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Re: Antarctic Icebergs
« Reply #332 on: November 16, 2020, 06:02:10 PM »
Much appreciated, Tealight!
Here's A-68A in yesterday's context. (Yellow 'square' identifies image preview location. South Georgia Island is to the ice island's northeast.)  Polar View image dated Nov. 15 [click for clearer images]
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Re: Antarctic Icebergs
« Reply #333 on: November 16, 2020, 08:52:04 PM »
Totally reminded me of Glove.


Stephan

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Re: Antarctic Icebergs
« Reply #334 on: November 18, 2020, 09:44:58 PM »
Referring to my post #327 I give a short update from B-22.
Since Nov 02 it has further moved into WNW-NW direction by approx. 0.6 km.
It seems B-22 has lost some its contact to underwater ridges or pinning points.
If it continues with this speed, it will open up the gateway as defined in post #327 within this melting season.
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baking

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Re: Antarctic Icebergs
« Reply #335 on: November 19, 2020, 05:20:55 PM »
Referring to my post #327 I give a short update from B-22.
Since Nov 02 it has further moved into WNW-NW direction by approx. 0.6 km.
It seems B-22 has lost some its contact to underwater ridges or pinning points.
If it continues with this speed, it will open up the gateway as defined in post #327 within this melting season.
Freaky, although I expect those larger icebergs will get stuck.

Stephan

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Re: Antarctic Icebergs
« Reply #336 on: November 20, 2020, 04:58:16 PM »

Freaky, although I expect those larger icebergs will get stuck.

Thank you for that animation. B-22's moving direction has changed (more N instead of WNW-NW). Maybe also a rotational aspect of its movement is present.

Concerning the larger icebergs, you may be right. Most of the icebergs west of that red longitude line had moved into that area through that gateway in the last years and got stuck on that underwater ridge.
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Stephan

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Re: Antarctic Icebergs
« Reply #337 on: November 22, 2020, 04:02:01 PM »
Update from Cork, our hero of last melting season.
He lies still grounded, roughly two thirds between SWT and Thwaites Eastern Ice Shelf. I am not sure whether the smaller bergs around him are Cork's calving products.

See attached picture, the smaller inlay shows his position (orange circle).
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Re: Antarctic Icebergs
« Reply #338 on: November 24, 2020, 12:19:25 AM »
Enjoy clicking on to Worldview on a daily basis to check progress of A68-A's movement east towards S. Georgia I. As of today (Nov. 23) my crude measurement indicates it is about 277 km west of the islands NW tip and has moved about 69 km east (w/ slight clockwise spin) from its location on Nov. 7.                           
                                                                                                                                         
Media (BBC) has reported possible doom and gloom for S. Georgia's foraging sea mammals and penguins but to contrary, wonder if a giant ice island might provide some habitat and feeding opportunities where none existed before. Structure often attracts critters. Looked on internet but not able to track down any information regarding this.


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Re: Antarctic Icebergs
« Reply #340 on: November 24, 2020, 02:11:49 AM »
Hi APMartie2, to do that you need to save the image to your device and then upload it as attachment to your post.
Thanks to your link, here's an even better Worlview output, an animation of the past month (made using the video camera icon on WV, optimized on EZgif to reduce size). Click to animate.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #341 on: November 24, 2020, 06:47:58 PM »
You two make a wonderful pair of collaborators! 

So, A68-A moved about half the distance to South Georgia in one month.  We may know about Christmastime (different cultures, different dates!  :-X) how close the two will get to each other.  (You know masses attract.  ::) :P)
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