Author Topic: Antarctic Icebergs (Read 123844 times)

Stephan · « **Reply #500 on:** February 02, 2022, 07:57:55 PM »

New developments at B-22 and its surroundings.
1. B-22's eastern end has moved around 1 km into N direction since yesterday, its western end did not move significantly. Is it now freely floating at its eastern edge and will the forces be strong enough to break it into (larger) pieces?
2. B-29 has further moved into N direction (2.5 km since Jan 31), B-28 into NW direction (2 km since Jan 31)
3. B-45 has lost its direct connection to Crosson Ice Shelf. New cracks in the fast ice/Ice mélange are indicated by a dotted blue line.
4. Grounded iceberg "green x" is still solidly grounded
5. Iceberg "red y" is now freely moving and has left its position into N direction (around 5 km since Jan 31
6. The distance between iceberg "green x" and B-22 (position "black z") has widened to 6 km.

Question: Will this general movement and widening of the distance between B-22 and the fast ice close to Thwaites and Crosson Ice Tongue/Ice Shelf allow the sea ice with all its icebergs in it to clear the sea south of B-22?

See attached picture.

oren · « **Reply #501 on:** February 03, 2022, 01:10:34 PM »

This is certainly bad news. The grounded icebergs and especially B-22 stabilized the region, reduced currents and helped maintain the fast ice.

baking · « **Reply #502 on:** February 03, 2022, 02:54:56 PM »

This calving from the Crosson Ice Shelf actually happened yesterday but I missed it.

baking · « **Reply #503 on:** February 03, 2022, 03:19:11 PM »

Today's 12-day GIF shows the Eastern end of Iceberg B22-A continuing to move North. If this projection doesn't ground on the underwater peak, then I think we can say that B22-A is floating free from it.

baking · « **Reply #504 on:** February 03, 2022, 03:45:10 PM »

I assume he is talking about B22-A, but it is all pretty vague:

https://apnews.com/article/doomsday-glacier-climate-science-4d80d7c466171b12d43a5de1de64cd4a

Giant iceberg blocks scientists’ study of ‘Doomsday Glacier’

EDIT: Here are some tweets from @rdlarter that give some context for the article

https://twitter.com/rdlarter/status/1489006310205145096

https://twitter.com/rdlarter/status/1489155447751852039

Phil42 · « **Reply #505 on:** February 04, 2022, 01:42:05 AM »

Wion News had a segment today about Thwaites, the blocked expedition and the general state of the area, including a short interview of someone on the expedition.

https://www.wionews.com/videos/large-chunks-of-ice-that-broke-off-from-thwaites-glacier-blocks-an-expedition-of-scientists-450218

baking · « **Reply #506 on:** February 04, 2022, 04:05:00 AM »

Just to be clear, all of these news stories today were based on the same AP piece. The problem is the "giant iceberg" has been there for twenty years and could not be the real reason they can't get to Thwaites this season. The actual explanation is the ice floes that moved in from the North, but that is not nearly as interesting.

https://twitter.com/rdlarter/status/1486474785882349568

Stephan · « **Reply #507 on:** February 04, 2022, 08:01:45 PM »

New developments at B-22 and its surroundings.
1. B-22 has moved around 0.5 km into N direction since yesterday, its eastern end traveled 5 km since Jan 31.
2. B-29 has further moved into N direction (7 km since Jan 31), B-28 into NNW direction (7 km since Jan 31).
3. B-45 has lost its direct connection to Crosson Ice Shelf and moved ca. 3 km since Jan 31.
4. South of B-45 another iceberg (red "B-") has calved from Crosson Ice Shelf (see baking's post from yesterday). Is it large enough to receive a number (15 * 5.5 km)?
5. Iceberg "green x" is still solidly grounded.
6. Iceberg "red y" is now freely moving and has left its position into N direction (around 14 km since Jan 31). It is heading towards the gap between B-22 (position "black z") and iceberg green "x" and has the potential to block this outlet (7.), if it gets grounded there.
7. The outlet distance between iceberg "green x" and B-22 (position "black z") has widened to 6.6 km.

See attached picture (size is around 90 * 140 km).

baking · « **Reply #508 on:** February 05, 2022, 03:27:41 PM »

Another 12-day low-res GIF of the Eastern end of Iceberg B22-A. Comparing it with the lat one, it looks like it has moved about 1 km in the past two days.

FredBear · « **Reply #509 on:** February 08, 2022, 01:40:46 PM »

Quote from: Stephan on February 04, 2022, 08:01:45 PM

New developments at B-22 and its surroundings.
1. B-22 has moved around 0.5 km into N direction since yesterday, its eastern end traveled 5 km since Jan 31.
2. B-29 has further moved into N direction (7 km since Jan 31), B-28 into NNW direction (7 km since Jan 31).
3. B-45 has lost its direct connection to Crosson Ice Shelf and moved ca. 3 km since Jan 31.
. . . See attached picture (size is around 90 * 140 km).

Looking at Worldview icebergs B28 and B29 had broken away from the Crosson Ice Shelf before March 2000 (2 years before B22 broke from Thwaites??) and they are still being shunted around the area. (There was another 'berg which did escape more quickly).
Cracks around B45 looked to have started to form before 2016 but it has only now begun moving away - in spite of so much sea ice surrounding it.

uniquorn · « **Reply #510 on:** February 08, 2022, 05:41:02 PM »

This one was outside the crop on the Antarctic ani
AWI sea ice concentration, v106, jan1-feb6
it disappears (temporarily?) on feb7

edit: had to check it was still there...
https://go.nasa.gov/3otxOHZ

baking · « **Reply #511 on:** February 10, 2022, 02:46:13 PM »

2-day GIF of the icebergs off of Crosson Ice Shelf including a bit of B22-A as it continues to rotate.

Stephan · « **Reply #512 on:** February 10, 2022, 07:22:28 PM »

The distance of the outlet between B-22-A (position "black z") and the grounded iceberg ("green x") has increased to 8.2 km (for the picture see my reply #507 from Feb 04)

Stephan · « **Reply #513 on:** February 12, 2022, 09:12:27 PM »

Latest developments around B-22-A
(unfortunately partly obscured by clouds)
Take home message = what a mess!

1. The sea south of B-22 (southern edge indicated by a dotted black line) is almost completely filled with sea ice, the two icebergs B-29 and B-28 and all the other smaller bergs derived from Crosson Ice Shelf and the top of the Thwaites Ice Tongue.
2. This mélange is moving into W direction (blue arrows)
3. The outlet (blue "o") has slightly widened to about 8.5 km (distance between black "z" on B-22 and grounded iceberg "green x"). Will this mélange be able to pass through this outlet? I am not sure..., but some of it has passed (all the ice SW of B-22 circled in yellow)
4. A lot of other smaller icebergs are grounded, many of them for years(!) in an arch like formation from "green x" and "red y" until "orange b" (marked by a black dotted line).
5. A part of the fast ice east of Bear Peninsula and N of Crosson has also become mobile (blue line).

See attached picture (size approx. 105 * 135 km)

baking · « **Reply #514 on:** February 13, 2022, 11:39:05 AM »

36-day GIF of Iceberg B22-A, the bergs off of the Crosson Ice Shelf, and Thwaites Tongue. Scaled down 5X, so 180 km on a side.

oren · « **Reply #515 on:** February 13, 2022, 11:48:14 AM »

Thanks for the animation.
It appears as if the western side of B-22 is still somewhat grounded, as it moves much more slowly than the eastern side.
The clean shearing off of the Thwaites tongue, the very large area of iceberg melange to its west and several very large Crosson icebergs further west, is very impressive (and obviously very disconcerting). In my layman's view it would appear as if the two larger grounded (or almost grounded) icebergs just to the east of the main tongue, near the corner of 106^o and 75^o, are what may have shielded the remaining tongue and melange and prevented further shearing. I sure hope they stay stuck.

baking · « **Reply #516 on:** February 17, 2022, 01:28:49 PM »

Today's low-res 2-day GIF of Iceberg B22-A, scaled down x4. Image is 80x96 km. After being stationary for a few days, it drifted Eastward away from the shallows to the West. You can see a grounded iceberg near the Eastern end (top of image) which gives a sense of how close the Eastern end is to grounding again or how close it is to slipping away.

Tor Bejnar · « **Reply #517 on:** February 17, 2022, 05:09:22 PM »

Certainly in a tight space. I see grounded icebergs above the 'top' and on all three sides of the 'bottom' quarter of the ice island.

baking · « **Reply #518 on:** February 17, 2022, 06:29:01 PM »

Quote from: Tor Bejnar on February 17, 2022, 05:09:22 PM

Certainly in a tight space. I see grounded icebergs above the 'top' and on all three sides of the 'bottom' quarter of the ice island.

Remember that the "bottom" or Western end is the oldest and has been floating for something like 50 years (30 as part of the Tongue, 20 as an iceberg.) So it could be a lot thinner than the surrounding smaller bergs. Also, if it keeps rotating counter-clockwise it could drift further along the shallows and will have less of an effect holding the sea ice in place. The one saving grace may be the two grounded icebergs to the North (left) about in the middle. Bathymetry shows some areas there less than 400 meters deep that may halt the rotation.

IceConcerned · « **Reply #519 on:** February 17, 2022, 07:00:42 PM »

I agree with all of the above mentioned, but do not forget that in the past months some chunks have been shed out of the Eastern part of the iceberg, so it may be less grounded there too than commonly assumed

Stephan · « **Reply #520 on:** February 18, 2022, 09:36:49 PM »

B-22 is further moving northward, slightly rotating counterclockwise.
Since Jan 31 almost 10 km at its eastern end, and 3 km westward movement at its northwestern tip. Wonder if it will keep up this speed to finally find open waters and float away completely.

This will have an impact on the sea ice between it and Crosson Ice Shelf.

baking · « **Reply #521 on:** February 22, 2022, 12:56:11 AM »

I've tracked the grounded iceberg to the North of B22-A. It's been there since June and when the sea ice broke up about a month ago it stayed in place. The one I'm referring to is shaped something like a shoe. The area it's in has a depth of less than 400 meters and may prevent B22-A from moving much further North. Or not. We will see.

45MB. Click at your own risk.

paolo · « **Reply #522 on:** March 08, 2022, 12:47:47 PM »

D-28 and the Armada of Icebergs it generated (in 2021) looked almost complete again around the Stancom-Wills Glacier Tongue, missing only a few stragglers and small vanguards.
This allows a look at the total volume of debris produced by D-28.
I've also highlighted the two future Brunt Ice Shelf icebergs, so you can see their surface and compare them to the other icebergs.

Image notations:
RLIS = Riiser-Larsen Ice Shelf
LIR = Lyddan Ice Rise
SWGT = Stancom-Wills Glacier Tongue
BIS = Brunt Ice Shelf
FI-1 and FI-2 = Future Icebergs of BIS

In this image one pixel corresponds to 200 m and the image is 370 x 350 km

Very large image, click twice to enlarge completely

FredBear · « **Reply #523 on:** March 09, 2022, 01:47:04 AM »

Thanks paolo. In : Where is D-28 headed?« Reply #52 on October 24, 2021 I put up an image of the "armada" as it was then.
It has basically just moved along the coast as expected and has been floating around the Stancom-Wills Glacier Tongue all summer.
There is a tendency for coastal ice to drift out to sea at this time of year (to be replaced by new sea ice as the water cools) and I think that this is now happening so most of the icebergs will start to drift west (to the left) across the top of the Weddell Sea this winter.
There is one smaller white 'berg (1/3 from FI-1, 2/3 from D-28) which I was wondering if it would drift south along the coast (like A74) but in the last few days it has been drifting in a more northerly direction . . .

FredBear · « **Reply #524 on:** March 09, 2022, 02:12:38 AM »

In the Weddell Sea iceberg A74 has been making its way south along the coastline this summer and is now being surrounded by new sea ice as it moves slightly out to sea.
Just to the north of A74 is A23A which has been rotating anticlockwise (it has almost completed a 360^o turn this summer), and moving around in the same areas it has occupied for many years. I am still wondering if it is floating round the centre of a gyre in this area?
The A76 icebergs have been drifting along the western side of the Weddell Sea, with A76A drifting further away from the coastline and beginning to move a little faster recently. New sea ice is now forming and movement of the pack will dictate where everything moves next . . .

Stephan · « **Reply #525 on:** March 13, 2022, 10:24:17 PM »

After weeks of cloudiness there is finally a clear day to watch the seas around my pet iceberg B-22.
The sea starts to freeze now in Austral autumn. I noticed several things, combined in the attached picture (size is approx. 130 * 105 km, N is roughly left to left below)
1. B-22 has moved some weeks ago, but seems to be almost stuck again. It had rotated counterclockwise, meaning a shift into N direction at its eastern end by 10 km, and a shift into W direction by 3 km at its western end since Jan 31.
2. Iceberg "red y" has moved 33 km northward since Jan 31 from the shores of Bear Peninsula and is now grounded between iceberg B-22 and iceberg "green x".
3. This means that the outlet ("blue o") between the line of grounded icebergs and B-22 (position "black z") has narrowed again to 4 km. This also means that this underwater ridge (green dotted lines) is able to "collect" a lot of icebergs. This will prevent the sea ice and the icebergs therein between B-22 and Crosson Ice Shelf to escape into open waters and this will help to protect the erosion of Crosson Ice Shelf and Thwaites Ice Tongue (not in the picture), even if B-22 will finally disappear.
4. The icebergs B-29, B-28 and B-45 have moved 29, 30 and 17 km since Jan 31.
5. The freshly calved iceberg B-?? (is it large enough to be given a number?) has rotated by 90° and moved around 21 km since Jan 31.
6. Iceberg "orange b" is solidly grounded at the southern end of the underwater ridge (green dotted lines) where it connects to Bear Peninsula.

Tor Bejnar · « **Reply #526 on:** March 13, 2022, 11:08:00 PM »

Thanks, Stephen,
Your very clear communication is much appreciated. I would have called the "green dashed lines" "yellow-green" or "greenish yellow" (it is a different color from the "green x"), but as they are the only "dashed lines," I was able to figure it out

FredBear · « **Reply #527 on:** March 17, 2022, 03:15:37 AM »

A new iceberg has been separating from the Roi Baudouin Ice Shelf - the tag of ice just to the west of the 30^o east line (the end is pointing into the bay at the top left) . Previously I thought it might have been changing angles but it now looks to be free even through cloud, image from Worldview on 15.03.2022.

paolo · « **Reply #528 on:** March 17, 2022, 05:04:38 AM »

This is an old iceberg that broke off a long time ago, at least before 17/05/2017, see the first S1 image (date and scale in the image: 1px ~54m, total length of the iceberg about 37km). But the western part (left) was grounded
This iceberg broke in two between 24/02/2022 and 03/03/2022 and the long part (about 30 km) is now free, see the animation (same resolution)

Click to animate and enlarge completely

FredBear · « **Reply #529 on:** April 11, 2022, 04:32:49 AM »

The "new iceberg" I mentioned in reply 527 (and aged by paolo above) has only moved a little since 17 March and the rest of the original 'berg remains grounded by the Roi Baudouin Ice Shelf.

FredBear · « **Reply #530 on:** April 11, 2022, 05:30:13 AM »

In the failing light of autumn I suddenly noticed that iceberg A23A can be seen closing in on the "armada" of 'bergs that have been accompanying D28 close to the Brunt Ice Shelf!
Of the main icebergs D30A(?) seems to be leading D28 westwards, with those more southerly icebergs traveling west less quickly than the ones to the north.
I am expecting the "armada" to largely continue the westward movements over the winter season . . .
A23A has again been drifting (4^o eastwards and almost 1^o north in the last summer) and turning close to 360^o anti-clockwise during that time - the question is whether it is far enough north to join the drift westwards this season or whether it is still trapped in a gyre?

There had been a smaller somewhat triangular iceberg drifting around the end of the Brunt Ice Shelf (where it reached its most southerly position around March 2nd) which I thought might join A74 in going south but it seems to have returned northwards since then - I thought it might be a good "drift indicator" specimen!

Often Distant · « **Reply #531 on:** June 19, 2022, 12:44:41 AM »

A76A set to drift far away through the dark season. It wants to be the first to see the sun rise. It will be interesting how it affects the extent of the ice around it over the coming months. It travelled roughly 500 miles in 12 months after breaking from the Ronne Ice Shelf.

Big movements on all bergs in the Weddell sea since sundown. Large flows of sea ice can still be seen being pulverized into slush through the freezing season.

A23A (the giant one) is very mobile now after long remaining largely caught in the same place as far back as can be seen on worldview.

FredBear · « **Reply #532 on:** June 19, 2022, 10:51:23 AM »

Thanks for those pictures OD.
I have been collecting the locations of A76A, A23A and some of the"Armada" with D28 in the night season (waiting for light to shine again), anticipating some significant change in the picture.
Now, halfway through the winter, we can see how far some things have moved in the darkness!
Sometimes it is not easy to judge the trajectories of the icebergs in this huge expanse of ice - but A23A has been continuing to spin anti-clockwise (especially since late May) and D28, D30A et al have accompanied it with a slightly west and southwards twist around it since around June 12.
The big question still remains - will A23A escape to the west this coming summer season . . ?

grixm · « **Reply #533 on:** June 30, 2022, 10:00:39 AM »

B-22 and other nearby icebergs continues to move about, refuses to be locked by fast ice despite it being high winter.

Attached animation is a comparison between now and 14 days ago. Top half has pivoted further toward the north

interstitial · « **Reply #534 on:** June 30, 2022, 10:39:52 AM »

south?

oren · « **Reply #535 on:** June 30, 2022, 10:41:17 AM »

North, away from the continent.

grixm · « **Reply #536 on:** June 30, 2022, 11:01:58 AM »

Sorry for the confusion that there's no dates on the images to show which is which, but as oren says, the frame where the iceberg is the furthest north (away from the content) is the most recent one.

interstitial · « **Reply #537 on:** June 30, 2022, 10:42:46 PM »

Often Distant · « **Reply #538 on:** July 10, 2022, 03:18:35 AM »

A good winter view of A74 (calved from the Brunt ice shelf early 2021) which has become a bit smaller in the dark. Ice bergs are distinguishable from multi year sea ice which is distinguishable from new sea ice.

FredBear · « **Reply #539 on:** August 04, 2022, 12:29:39 PM »

Further to reply 531 - on 2022 Aug 03 Worldview A76A already can be sailing into the sunrise - north of the Antarctic Peninsular and towards its doom in the South Atlantic . .

Other icebergs are still hiding in darkness in the Weddell Sea . . how much they have moved will become apparent later.

gerontocrat · « **Reply #540 on:** August 06, 2022, 07:08:45 PM »

A nice view of B22 dated 5 August 2022 from polarview. ( https://www.polarview.aq/antarctic )

A lot of cracks in the surrounding ice & what looks like a pathway for the little bergs to travel down.

click image to enlarge

paolo · « **Reply #541 on:** August 21, 2022, 10:11:42 AM »

Departure for the far north?

Click to animate

uniquorn · « **Reply #542 on:** August 21, 2022, 11:14:36 AM »

Low res version

paolo · « **Reply #543 on:** August 28, 2022, 07:30:12 PM »

A76A is now out of the sea ice and can be easily and simply tracked by looking at the Polar View map. It is likely to stay out, even if temporarily it can still hide there, and should pass to the north of the South Orkney Islands before facing the "Furious Fifties" (see the first image)

The second image (very large S1 image, click twice to enlarge) shows us that apparently for the moment this iceberg has not yet suffered any damage and could survive for some time once it leaves the cold waters of Antarctica.

Stephan · « **Reply #544 on:** September 18, 2022, 03:52:45 PM »

Comprehensive movement of B-22 during Austral winter 2022.

I compared EOSDIS images from March 13, 2022 with September 13, 2022 of B-22 and its surroundings.
B-22 has moved into N direction (eastern end) by 2-3 km and into W direction (western end) by 0.5-3 km, showing a counterclockwise rotation.

B-29 has entered the shallow waters S of B-22 and serves now, together with a lot of smaller icebergs that are grounded there for some years now, as a new large cork for the sea ice / ice mélange south of B-22. Will it stay there for a while?

See attached picture.

Tealight · « **Reply #545 on:** September 30, 2022, 02:11:28 AM »

In a few days iceberg A76A will leave the southern ocean (crossing 60S). The surface is already at 0C ready to melt heavily in summer. A small part has also broken off recently. May the waves batter it's sides and chip it away.

FredBear · « **Reply #546 on:** September 30, 2022, 12:15:31 PM »

As A76A leaves the safety of the Antarctic ice others are following.
A76B and A76C are following more slowly in the pack ice.
The D28 "Armada" has mostly looped across the north of A23A going westwards towards the Antarctic Peninsular and will show an increasing drift northwards with time.
The exception I have noticed is A77 which is following the coastline south of the Brunt Ice Shelf (and iceberg A74) to do a grand tour of the southern limits of the Weddell Sea.
A23A itself has rather been marking time, moving relatively little since the sun has risen - is it still "touching the bottom" and in danger of grounding again?

uniquorn · « **Reply #547 on:** September 30, 2022, 12:43:13 PM »

awi sic-leads v110, Weddell Sea, aug1-sep29 (12MB)

paolo · « **Reply #548 on:** October 03, 2022, 08:58:59 PM »

Attached are Sentinel2 images of A76A calving with commentary
The first animation is a post-calving image with two zooms (the calving area and the area of another very small calving)
The second animation is a pre-calving image with a zoom on the rift that caused the calving
This calving occurred on the face of A76A which was, before calving, in front of the ice shelf and the rift that caused the calving certainly existed at the time of calving of A76A.
The third image shows the current position of A76A

Large images, click twice to enlarge them completely (and animate the two animations)

FredBear · « **Reply #549 on:** November 03, 2022, 07:01:32 PM »

Another month on and A76A continues to drift clear of ice northwards above 60^oS off the Antarctic peninsular, meanwhile its parts B & C are left in the pack ice around 67^oS, close to 60^oW.
D30A is drifting towards the 70^oS line and is likely to cross it in the next couple of weeks? D28 is following but a bit further south.
A23A is following on more slowly (73^o25'S last week) but a long way ahead of where it was last year.
(The last three icebergs can be seen in uniquorn's post no. 547 above, with the dark trails behind them in the upper part of the solid sea ice. A76A is the large iceberg to the top left, clear of the pack ice and islands.)

(Another iceberg, B22 from Thwaites in the Amundsen Sea region, looks to be shifting northwards and bits breaking off SW edge in the last couple of days under cloud, this is another blocking 'berg now also on the move?)

News:

Author Topic: Antarctic Icebergs (Read 123844 times)