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FredBear

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Re: Antarctic Icebergs
« Reply #700 on: August 16, 2023, 06:36:25 PM »
It is interesting that both D28 and D30A just about slipped out of the pack ice earlier this year. They are located in the same area as A76A was a year ago (Worldview 2022 August 15) so it will interesting to see how they also progress as A76A hung around for quite a time before it fairly rapidly set sail for South Georgia and its current demise as scattered numbered icebergs around that island.
Most of the numbered icebergs around Antarctica are towards the western Weddell Sea, with a lot drifting north of the Peninsular (Worldview - Events)
A23A is still in the pack ice (in the last season that was rather persistent off the northwestern Antarctic Peninsular) so I wonder how long before it escapes too?

Often Distant

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Re: Antarctic Icebergs
« Reply #701 on: September 01, 2023, 02:31:22 AM »
High winds. Slushy seas. New icebergs. 20 East. Little warning. A speckle collided into the ice shelf.
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HapHazard

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Re: Antarctic Icebergs
« Reply #702 on: September 01, 2023, 03:08:56 AM »
A speckle collided into the ice shelf.
Judging by that animation, I'm pretty sure that speckle was a piece from a neutron star.
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FredBear

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Re: Antarctic Icebergs
« Reply #703 on: September 08, 2023, 01:20:01 AM »
That calving is from the base of "Tongue 2" from Paolo's post « Reply #448 on: June 18, 2021, 02:40:07 PM »

That ice shelf (Borchgrevink) has staged another retreat!
Paolo's original images:-


grixm

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Re: Antarctic Icebergs
« Reply #704 on: October 07, 2023, 10:53:01 PM »
A76 has continued its breakup but as is now in many pieces, but it's still far from melted out.  Look at how long and thin some of the slices are, though!
The pieces are scattered north of South Georgia. Some of them has reached north of 50 degrees. Not that far from the record latitude of an antarctic iceberg, which is 42.5 degrees south as far as I can tell, tied by C-02 and A-57a.
(image)

Meanwhile, D-30a and D-28 recently freed themselves of the rest of the sea ice and accelerated north-eastward. They moved around 300km in just the last few days! Currently located north of Coronation Island.

Yuha

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Re: Antarctic Icebergs
« Reply #705 on: October 29, 2023, 06:21:17 PM »
In the Antarctic melting season thread, oren just posted a sea ice animation:
https://forum.arctic-sea-ice.net/index.php/topic,4068.msg386217.html#msg386217

There seems to be three ice bergs doing a crazy dance north of Weddel Sea. Are they D-30a and D-28 and perhaps a fragment split from one of them?

FredBear

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Re: Antarctic Icebergs
« Reply #706 on: October 30, 2023, 12:50:15 AM »
Yuha, the "small" iceberg is D29B, which appeared to be knocked from the continent by D28 (the most northerly of the three) shortly before D30A (the most southerly one) was dislodged by the same iceberg just before June 11 2021. First recorded in reply 448 here by paolo on June 18 2021.
It is interesting to see them dancing around in the animations. D30A has been drifting slightly south lately?

If you are looking at the Antarctic view in Worldview, go to the "Events" tag under the title and there are tracks for many icebergs if you click on the icons you can see there.

The remains of A76A (labelled A-L) have mostly(?) drifted north of South Georgia and a few can now be seen heading towards the northern edge of that picture (image 2023 Oct 26).see:-

https://worldview.earthdata.nasa.gov/?v=-4242813.364570522,2049393.063353159,-705917.3645705217,4031857.063353159&p=antarctic&e=EONET_5388,2023-10-26&efs=true&efa=false&efd=2023-07-01,2023-10-29&l=Reference_Labels_15m,MODIS_Terra_Sea_Ice(hidden),MODIS_Aqua_Sea_Ice(hidden),VIIRS_SNPP_Brightness_Temp_BandI5_Night(hidden),VIIRS_SNPP_Brightness_Temp_BandI5_Day(hidden),VIIRS_NOAA20_Brightness_Temp_BandI5_Night(hidden),VIIRS_NOAA20_Brightness_Temp_BandI5_Day(hidden),MODIS_Aqua_Brightness_Temp_Band31_Night(hidden),MODIS_Aqua_Brightness_Temp_Band31_Day(hidden),MODIS_Terra_Brightness_Temp_Band31_Night(hidden),MODIS_Terra_Brightness_Temp_Band31_Day(hidden),VIIRS_SNPP_DayNightBand_ENCC(hidden),Coastlines_15m,BlueMarble_NextGeneration(hidden),VIIRS_NOAA20_CorrectedReflectance_TrueColor(hidden),VIIRS_SNPP_CorrectedReflectance_TrueColor(hidden),MODIS_Aqua_CorrectedReflectance_TrueColor(hidden),MODIS_Terra_CorrectedReflectance_TrueColor&lg=true&t=2023-10-26-T23%3A14%3A28Z
« Last Edit: October 30, 2023, 01:08:04 AM by FredBear »

vox_mundi

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Re: Antarctic Icebergs
« Reply #707 on: November 09, 2023, 09:20:56 AM »
New AI System Can Map Giant Icebergs From Satellite Images 10,000 Times Faster Than Humans
https://phys.org/news/2023-11-ai-giant-icebergs-satellite-images.html

Scientists have trained an artificial intelligence (AI) system to accurately map—in one-hundredth of a second—the surface area and outline of giant icebergs captured on satellite images. The paper, titled "Mapping the extent of giant Antarctic icebergs with Deep Learning," is published in The Cryosphere.



It is a major advance on existing automated systems, which struggle to distinguish icebergs from other features in the image. Manual—or human—interpretation of the image is more accurate, but it can take several minutes to delineate the outline of a single iceberg. If that has to be repeated numerous times, the process quickly becomes time-consuming and laborious.

"Using the new AI system overcomes some of the problems with existing automated approaches, which can struggle to distinguish between icebergs and other ice floating on the sea or even a nearby coastline which are present in the same image."

Dr. Braakmann-Folgmann and her colleagues used an algorithm called U-net—a type of neural network—to "train" a computer to accurately map the outline of icebergs from images taken by Sentinel-1 satellites operated by the European Space Agency.

As part of the study, the effectiveness of the U-net algorithm was compared to two other state-of-the-art algorithms used to map icebergs. They are known as k-means and Otsu. The algorithms were programmed to identify the biggest iceberg in a series of satellite images.



The system has been tested on satellite images of seven icebergs, which were all between the size of the city of Bern—54 km2; and Hong Kong—1,052 km2. For each of these icebergs, up to 46 images were used that covered all seasons from 2014-2020.

Over a series of tests, U-net outperformed the other two algorithms and was more effective in delineating the outline of an iceberg in images taken when environmental conditions were challenging, such as the image capturing a lot of ice structures.

On average, the U-net algorithm showed only a 5% lower estimate of the area of an iceberg. In contrast, the k-means and Otsu algorithms returned—on average—figures for iceberg area that were 150% to 170% too large, probably because the algorithms were including sea ice and even nearby coastline in the calculations.

In machine learning, the F1 score is an evaluation of how well an algorithm performs and ranges from 0 to 1, with values closer to one displaying more precision. U-net achieved an F1 score of 0.84. The two other algorithms both scored 0.62.

Mapping the extent of giant Antarctic icebergs with Deep Learning, The Cryosphere (2023).
https://tc.copernicus.org/articles/17/4675/2023/
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FredBear

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Re: Antarctic Icebergs
« Reply #708 on: November 09, 2023, 03:33:36 PM »
The state of things (Worldview):-

https://worldview.earthdata.nasa.gov/?v=-2478734.0527127767,1793824.4106241101,-2256526.0527127767,1916704.4106241101&p=antarctic&t=2023-11-06-T13%3A16%3A27Z

The drifting ice in the northwestern Weddell Sea is shrinking back to the A23A iceberg recently, by
moving about in the dates you can see the movements. When will A23A break clear in its voyage north and will it sail rapidly or not?
Reducing the magnification and looking up can reveal South Georgia with D28 approaching over the past few days. On the 3rd November there were remains of A76A grinning through the clouds about 680km north of South Georgia where they have probably collapsed into a white mush of smaller icebergs (they were smaller and narrower in the days before collapse) - a last glimpse before they melt away or move north of the limit of the map.

FredBear

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Re: Antarctic Icebergs
« Reply #709 on: November 24, 2023, 09:43:43 AM »
The BBC has noticed A23A:-

https://www.bbc.co.uk/news/science-environment-67507558

In recent days Worldview has shown it moving westwards towards Elephant Island where other visiting icebergs have loitered and delayed their passage northwards    .    .    .

Phil.

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Re: Antarctic Icebergs
« Reply #710 on: January 16, 2024, 10:07:37 PM »
Recent news on A23A from BBC also mentions D28.  Some great photographs.

https://www.bbc.com/news/science-environment-67986443

FredBear

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Re: Antarctic Icebergs
« Reply #711 on: January 30, 2024, 02:17:32 AM »
A23A has completed one anti-clockwise revolution and moved 100km+ in the past month.
Although it is moving more slowly recently it was slightly more distant from Elephant Island and did not hang around there as long as some other icebergs. I wonder how long it will take to get to South Georgia - or whether it will get hung up on the way?
D30A is now breaking up north of South Georgia with D28 just fraying at the edges a bit further north.

Stephan

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Re: Antarctic Icebergs
« Reply #712 on: February 12, 2024, 10:15:39 PM »
Tracking B-22.

My pet iceberg is now north of central Getz Ice Shelf, slowly drifting westward. The distance to Getz is at 250 km, the distance to its former postition (red circle) is 375 km.
It still looks quite intact. Please compare its structural integrity - after such a long time being partly grounded for almost two decades and now being pushed around by waves, currents and wind - with the structure of today's Thwaites Ice Tongue.

See attached picture. N is left down.
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FredBear

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Re: Antarctic Icebergs
« Reply #713 on: February 14, 2024, 09:48:45 PM »
A23A has been reported again as turning anticlockwise by the BBC:-

https://www.bbc.co.uk/news/science-environment-68292946

As well as turning it has also been drifting slightly south recently and the BBC also says
"It cannot be seen in the satellite imagery - but A23a is loitering just behind the South Scotia Ridge, which is like a submerged continuation of the peninsula.

Once the berg crosses over this ridge, it will enter the Antarctic Circumpolar Current, one of the most powerful movements of water on the planet.

And this should push A23a, aided by strong westerly winds, to the north-east."