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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #350 on: December 08, 2020, 07:47:36 PM »
Last month, yesterday and what's next?

As they say, "Past behavior doesn't predict future performance."  Especially when considering the perspective!

A68-A images from EOSDIS
  • Frame 1: Nov. 7 image
  • Frame 2: Dec. 7 image
  • Frame 3: Dec. 7 image with A68-A enhanced
  • Frames 1 & 3 grafted together with arrows suggesting a trend
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #351 on: December 08, 2020, 08:07:06 PM »
Or just EOSDIS's Dec 4, 5, 6, 7, and 8 images
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aperson99

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Re: Antarctic Icebergs
« Reply #352 on: December 08, 2020, 08:31:51 PM »
Look at nullschool for waves, currents, and wind around South Georgia. What's eerie is that the iceberg is a big blob moving around, affecting waves.

charles_oil

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Re: Antarctic Icebergs
« Reply #353 on: December 10, 2020, 03:35:02 PM »
There is a useful report, graphics and link to the video of the recent flyover of A68 at:

  https://gcaptain.com/gigantic-iceberg-threatens-to-crash-into-south-atlantic-island/

Graphic from Polarview - shows blue line at 200m depth - possible grounding....

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Re: Antarctic Icebergs
« Reply #354 on: December 10, 2020, 09:37:27 PM »
Update from my pet iceberg B-22 NW of Thwaites.

Its movement has stopped, four weeks now without any significant change of position.

The sea ice south of it has now broken up into hundreds of pieces. Some days of westerly (!) winds have blown it out into NE direction. The usual exit, the bottleneck in its SW, seems to be even more blocked by a lot of new grounded icebergs (circled in orange).
The sea ice further into direction of Thwaites now becomes weaker. Some larger parts, marked in a green square, have been cut off in the last days. A new rift has opened (blue line); this ice will follow soon.

Just wondering how far this open sea will move towards Thwaites and Crosson ice shelves/ice tongue this austral summer.

See attached picture.
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paolo

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Re: Antarctic Icebergs
« Reply #355 on: December 11, 2020, 04:29:47 PM »
For A68 fans, PolarView is thinking of you:

> Low resolution image of the 09/12 of A68 and the western part of South Georgia.
   I present here a reduced image

> High-resolution image of 11/12 of South Georgia and, for the moment, a small part of A68, but in the next images it will gradually enter completely in the image frame.
   I present here :
   >> a reduced image
   >> a zoom on a small piece of its North front with small detached icebergs. Large image, click to zoom

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #356 on: December 11, 2020, 10:18:34 PM »
EODIS WorldView of A68-A and South Georgia Island for December 11, then 8, 9, 10 and 11 (again).

Looks like the ice island is headed eastward and will miss getting grounded near South Georgia.
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baking

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Re: Antarctic Icebergs
« Reply #357 on: December 14, 2020, 04:05:25 PM »
Really nice, long story about A68-A with lots of graphics and history:

https://graphics.reuters.com/CLIMATE-CHANGE/ICEBERG/yzdvxjrbzvx/index.html

gerontocrat

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Re: Antarctic Icebergs
« Reply #358 on: December 14, 2020, 05:28:21 PM »
A-68-A is now at the mercy of above zero air temperatures, maximum insolation at around 55o South + at the mercy of a succession of lows as it is at the edge of the circumpolar winds.

It will be damaged, but how severely? Perhaps a poll about when and how much damage?

ps : Look carefully at the 1st (and last) image and see a white blob SW of S Georgia - A-68-A cooling local temperatures?
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Re: Antarctic Icebergs
« Reply #359 on: December 15, 2020, 04:17:51 AM »
Hycom and Mercator appear to place ocean temperatures near but slighlty above 0 C.

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #360 on: December 15, 2020, 03:07:37 PM »
Fox News!  Iceberg the size of Delaware drifting toward island in South Atlantic Ocean
Quote
A team of scientists is being sent to study the world’s biggest iceberg, which is potentially on a collision course with an island in the South Atlantic Ocean, according to reports.
...
The British Antarctic Survey (BAS) will lead the expedition that will see researchers fly out to the Falklands on Jan. 11, where they will quarantine, hop on the RRS James research ship, and embark on a three-day voyage to the iceberg.

“Even though icebergs are common, we’ve never had anything this size before, so it’s a first for us,” said Prof. Geraint Tarling, a biological oceanographer at BAS. “It brings a wholesale change to the environment.”

“If the iceberg does ground, we could be looking at this being there for up to 10 years because it’s so large. It’ll be a huge problem,” he continued.

When the supply and research ship arrives at the iceberg, scientists will collect and study animals in the water. They will also launch two robotic submarines, called gliders that will measure the temperature, salinity and levels of phytoplankton in the water around the iceberg, according to the news organization.

As the gliders patrol the area over a four month period, scientists hope to build up a picture of the iceberg’s impact on the environment.
...
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gerontocrat

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Re: Antarctic Icebergs
« Reply #361 on: December 15, 2020, 03:08:17 PM »
https://www.theguardian.com/environment/2020/dec/15/scientists-plan-mission-to-biggest-iceberg-as-it-drifts-towards-island

Scientists plan mission to biggest iceberg as it drifts towards island

Team will study effects on environment of A-68A, which is heading for South Georgia

Quote
Researchers at British Antarctic Survey (BAS) will fly out to the Falklands on 11 January, quarantine themselves to ensure they are free from coronavirus, and then embark on a three-day voyage to the iceberg onboard the research ship the RRS James Cook.

“Even though icebergs are common, we’ve never had anything this size before, so it’s a first for us,” said Prof Geraint Tarling, a biological oceanographer at BAS. “It brings a wholesale change to the environment.”

Strong ocean currents are steering the iceberg, which has a surface area of around 1,500 sq miles (4,000 sq km), from deep water towards the shallower waters of the continental shelf that surrounds South Georgia.

The edge of the shelf is rich in phytoplankton, krill and other species low on the food chain, making it an important feeding ground for penguins, seals and whales. “The biodiversity of this area is as rich as you’d find in the Galápagos,” said Tarling.

The waters around South Georgia are about 4C, but in the vicinity of the iceberg the temperature could fall a couple of degrees. The cooler temperature and release of what could potentially be billions of tonnes of fresh water into the region could be devastating for the feeding ground.

“If the iceberg does ground, we could be looking at this being there for up to 10 years because it’s so large. It’ll be a huge problem,” said Tarling.

Beyond disrupting the ecosystem, if the iceberg gets stuck on the continental shelf it will block off a large stretch of feeding ground where krill are most abundant. That could prevent penguins and seals from finding food nearby for themselves and their young in the breeding season.

Tarling said that while whales might be able to find other feeding grounds, large colonies of penguins and seals could not leave the island to go far. “They are fixed to their base and without being able to get out, feed and get back quickly, they have got a real problem.”

When the research ship arrives at the iceberg, the scientists will use nets and bottles to collect and study animals in the water. Two robotic submarines called gliders will be launched to measure the temperature, salinity and levels of phytoplankton in the water around the iceberg.

The gliders will patrol the region for four months, rising from their dives and transmitting data back to the ship. By combining this information with that from the ship-based studies, scientists will build up a picture of the iceberg’s impact on the environment.

Povl Abrahamsen, the chief scientist on the mission at BAS, said the latest images showed the iceberg was about 60 miles off the coast of South Georgia. “It may be the iceberg ends up bumping and scraping along the edge of the shelf or breaks clear of the islands. But it may also get grounded and stay around for months or years. At this stage it’s very difficult to predict what will happen next,” he said.
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #362 on: December 15, 2020, 03:19:47 PM »
EODIS WorldView of A68-A and South Georgia Island for December 14 to Dec. 8 and forward in time again.

A68-A is doing a little dance for us, now that we're watching!
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KenB

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Re: Antarctic Icebergs
« Reply #363 on: December 15, 2020, 10:26:00 PM »


A68-A is doing a little dance for us, now that we're watching!

I'm trying to understand the dynamics of a system this massive.  AFAICT from some casual looking, the northernmost part of A68-A might now be just about at the point where it makes contact with the ocean bottom, if indeed it's drafting about 200M.  So my naive physical intuition would be that the clockwise rotation would get stopped and perhaps reversed, bringing the "finger" back toward the north.  But then again, considering the mass involved and the forces required to rotate something that big in the first place, perhaps it will just shear off either or both of the underside of the iceberg and the ocean bottom and continue rotating clockwise. 

One thing's for sure, the momentum of A68-A, the magnitude of the frictional forces if it grounds, and the force required to spin something like that somewhere near 20 degrees in 24 hours are all just mind-boggling.
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Re: Antarctic Icebergs
« Reply #364 on: December 16, 2020, 03:20:36 AM »
There are a number of icebergs that are "wriggling" (moving a bit but not completely free) this year:-
A23A has turned about 90° anticlockwise and drifted back and forth a little in the last year after being virtually stationary for many years.
B22A has drifted slightly northwards and frayed a little at the edges. (Stephan is following that in detail).
I have noticed that B09B, C15 and C29 ceased to be labelled as "grounded" on the iceberg location table recently but they have not moved far yet.

A68A is moving in headline ways now but A68C has disintegrated and fallen out of being tracked.
D28  is still moving westwards slowly at the moment but it was moving more rapidly earlier in the year:-
 17/07/2020 @  66°35'S  59°59'E.
 11/12/2020 @  65°23'S  54°52'E

I have continued to record changing locations for a few icebergs but have not continued with the updates every 5 weeks as many movements had slowed during the antarctic winter.

The "natice" source has had a couple of glitches recently, (once the locations were in decimal degree fractions), and today I cannot access the data because of a fault ("It’s likely the website’s certificate is expired, which prevents Firefox from connecting securely."):-     https://www.natice.noaa.gov/pub/icebergs/Iceberg_Tabular.pdf

grixm

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Re: Antarctic Icebergs
« Reply #365 on: December 16, 2020, 11:14:12 PM »
For reference, I made a map showing how big A68a is in comparison to Europe.

Tealight

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Re: Antarctic Icebergs
« Reply #366 on: December 17, 2020, 03:54:52 PM »
Say hello to A68D. I doubt it will be with us for long.

must click image for animation

KenB

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Re: Antarctic Icebergs
« Reply #367 on: December 17, 2020, 05:12:54 PM »
Say hello to A68D. I doubt it will be with us for long.


Looks to be about 150 km^2, or 2.5 Manhattans.  And I wonder if there might be an A68E before too long, judging from what looks like a large crack across the northern end.
"When the melt ponds drain apparent compaction goes up because the satellite sees ice, not water in ponds." - FOoW

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #368 on: December 17, 2020, 09:06:15 PM »
Dec. 17 Worldview image shows more separation.  (D is circled.)
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oren

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Re: Antarctic Icebergs
« Reply #369 on: December 17, 2020, 11:29:06 PM »
Could the breakup be triggered by bumping into the seafloor?

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #370 on: December 18, 2020, 01:21:09 AM »
That's what I suspect, Oren.
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Re: Antarctic Icebergs
« Reply #371 on: December 18, 2020, 03:57:13 PM »
Both bits from A68A are still moving in the last 2 days (on Worldview) - something might be rubbing the bottom but no point of rotation    .    .    .

Iceberg locations for day347 (13 December) were given on:-
https://www.scp.byu.edu/current_icebergs.html

But no number for the new 'berg yet

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Re: Antarctic Icebergs
« Reply #372 on: December 18, 2020, 06:04:37 PM »
Seems likely to me that A68A is bottoming; that the bottoming is the factor causing the fracturing; that the fracturing is off the centerline of the main berg; and that the energy release from the fracture is generating the rotation of the remaining A68A, because the separating piece is (perhaps momentarily) pinned against the bottom at the time of the break.

Anyone have an alternative hypothesis that may explain the sudden spin? 

Edit: Rethinking the matter because the spin seems to have begun before the visible breakup began; so, while the breakup could have provided a kick, another force seems to have initiated the rotation.
« Last Edit: December 18, 2020, 07:21:47 PM by steve s »

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Re: Antarctic Icebergs
« Reply #373 on: December 18, 2020, 07:15:53 PM »
Could the breakup be triggered by bumping into the seafloor?

There are loads of reefs in the vicinity of the present location of A68A:

Please click on image to enlarge and animate!
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Re: Antarctic Icebergs
« Reply #374 on: December 18, 2020, 07:41:07 PM »
Could the breakup be triggered by bumping into the seafloor?

There are loads of reefs in the vicinity of the present location of A68A:

Please click on image to enlarge and animate!

So the wild life is somewhat protected?
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #375 on: December 18, 2020, 10:09:36 PM »
WorldView Dec 14-18

Looks surgical to me.  Any reports of UFOs in the vicinity on the 15th?  (Very convenient when we cannot see through the clouds!)

I imagine a bump may have caused the end to be knocked off, but an 'on the side' bump, not a 'shoved up the ramp and get stuck (and get broken off)' bump.  Definitely no ice got stuck for a day!  See Bathymetry below, from Fretwell, Peter & Tate, Alexander & Martin, Tara & Belchier, Mark. (2009). Compilation of a new bathymetric dataset of South Georgia. Antarctic Science. 21. 171 - 174. 10.1017/S0954102008001703. .  The views ("distortions"), of course, are very different.

I suspect good old fashioned ocean currents are what is spinning the whole shebang.
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Re: Antarctic Icebergs
« Reply #376 on: December 19, 2020, 01:35:22 AM »
Sorry, excuse my bad english

gerontocrat

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Re: Antarctic Icebergs
« Reply #377 on: December 19, 2020, 01:06:25 PM »

https://www.theguardian.com/world/2020/dec/18/massive
Huge Antarctic iceberg headed towards South Georgia breaks in two

Researchers fear iceberg may disrupt underwater ecosystems and block penguins looking for food


Quote
Strong currents have taken hold of a massive Antarctic iceberg that is on a collision course with South Georgia island, causing it to shift direction and lose a major chunk of mass, a scientist tracking its journey said on Friday.

As the iceberg, dubbed A68A, approached the western shelf edge of the south Atlantic island this week, it encountered strong currents, causing it to pivot nearly 180 degrees, according to Geraint Tarling, a biological oceanographer with the British Antarctic Survey.

“You can almost imagine it as a handbrake turn for the iceberg because the currents were so strong,” Tarling said.

That was when the iceberg appeared to clip the shelf edge, and caused a large piece to break apart. That new piece is an iceberg in its own right and already has a name: A68D.

Scientists have been watching for weeks as the massive iceberg, last measured at 4,200 sq km, rode a fast-track current towards the island.

Researchers feared that, as the iceberg closed in on the wildlife-rich island, it could grind into the seabed, disrupting underwater ecosystems. They were also worried that it might block penguins making their way into the sea for food.

As of Friday, the original A68A iceberg was about 50km (31 miles) from the island’s west coast. It appeared, however, to be heading south-east towards another current that would probably carry it away from the shelf edge before sweeping it back around toward the island’s eastern shelf area.

That means it could still cause an environmental disaster for local wildlife, but along the island’s eastern coast rather than the south-west.

“All of those things can still happen, nothing has changed in that regard,” Tarling said.

The new smaller iceberg, A68D, is moving further away from the original. Scientists don’t yet know if it will follow the same path, or become lodged somewhere else on the shelf. An estimate of A68D’s size was unavailable.

Scientists had predicted some chunks could break away from A68A as it approached the island, and more breakage is possible.
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Espen

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Re: Antarctic Icebergs
« Reply #378 on: December 19, 2020, 06:13:49 PM »
That image from the article above has nothing to do with A68A?
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Re: Antarctic Icebergs
« Reply #379 on: December 19, 2020, 09:16:25 PM »
That image from the article above has nothing to do with A68A?

Hard to be sure, but I think that might be a small shard that had broken off.  Here's an earlier story with an actual image of A68A with a similar-looking small berg in the foreground:  https://www.theguardian.com/environment/2020/dec/15/scientists-plan-mission-to-biggest-iceberg-as-it-drifts-towards-island

In all, though, not a great story from the Grauniad - it took me all of 30 seconds on Worldview to determine that A68D was about 150 km^2, but we get:  "An estimate of A68D’s size was unavailable."
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Re: Antarctic Icebergs
« Reply #380 on: December 21, 2020, 07:31:35 PM »
Today a partial view of A68a with Sentinel1 low resolution.
We can see that the cut between A68d and A68a was clear and the two edges still correspond very well (apart from the break there does not seem to have been any other major event).
A68d has rotated 90° relative to A68a and now between the two there is about 40 km (in the image is noted the distance between the extreme edges of the break).

The image is very large, click to enlarge

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #381 on: December 21, 2020, 07:33:54 PM »
You beat me by 2 minutes!  :)
South Georgia at the top.  PolarView image from Dec. 21
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #382 on: December 21, 2020, 07:50:50 PM »
One can also see something on the Sentinel Playground site
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Re: Antarctic Icebergs
« Reply #383 on: December 22, 2020, 02:33:35 PM »
It's broken
It happened between the 21/12 22h42 and the 22/12 07h17.
Attached two versions of the animation:
> the first one very small
> and the second one slightly reduced (to animate it you have to click on it and to enlarge it click again).

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Re: Antarctic Icebergs
« Reply #384 on: December 26, 2020, 01:13:19 PM »
A-68A Iceberg Thinning at 2.5 cm per Day
https://phys.org/news/2020-12-a-68a-iceberg-thinning-cm-day.html




Using data from four different satellites, scientists from the Centre for Polar Observation and Modelling at the University of Leeds have produced the first assessment of the iceberg's changing shape.

The team first built a map of the icebergs initial thickness from measurements recorded by ESA's CryoSat satellite radar altimeter in the 12 months before it calved. This detailed map reveals that A-68 was originally, on average, 232 m thick, and 285 m at its thickest point. The berg has 30 m deep channels oriented parallel to its narrow side following the direction Larsen ice shelf was flowing out to sea before it snapped—a common feature related to ocean melting.

Since it has been drifting in the ocean, the iceberg's position and shape have been captured in a sequence of 11 images taken by two different satellites—the Copernicus Sentinel-1 mission, which has an all-weather and year-round imaging radar, and NASA's MODIS, which records images that are visible to the naked eye.

The imagery shows that the iceberg has halved in size from an initial area of 5664 sq km to its present extent of just 2606 sq km. A large proportion of this loss has been through the creation of smaller bergs, some of which are still afloat.

On average, the iceberg has thinned by 32 m, and by over 50 m in places—around a quarter of its initial thickness. When combined, the change in thickness and area amount to a 64% reduction in the iceberg's volume from 1467 to 526 cubic kilometers.



At its thickest section, the A-68A iceberg currently has a 206 m deep keel, and so the main section is unlikely to travel much closer to the island until it thins or breaks apart. However, two relatively large fragments which broke away on 21 December are considerably thinner, with keels that are up to 50 m shallower, and so these pose the greatest immediate threat.

Since it broke free, the average melting rate of A-68 has been 2.5 centimeters per day and the berg is now shedding 767 cubic meters of freshwater per second into the surrounding ocean—equivalent to 12 times the outflow of the River Thames.

http://www.esa.int/Applications/Observing_the_Earth/CryoSat/A-68A_iceberg_thinning_at_2.5_cm_per_day
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Tor Bejnar

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Re: Antarctic Icebergs
« Reply #385 on: December 26, 2020, 02:19:26 PM »
Just emphasizing the local environmental impact:
"[A68-A, etc.] is now shedding 767 cubic meters of freshwater per second into the surrounding ocean—equivalent to 12 times the outflow of the River Thames."
There are, however, hundreds of rivers with more than twice this outflow.  But the local environment isn't used to it.
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Re: Antarctic Icebergs
« Reply #386 on: December 27, 2020, 11:39:10 AM »
The 2020 title in the category long distance goes to B09I with an impressive 3711km travelled. A true champion indeed. Far behind in second place comes A68C with 2471km. Close behind comes D21B snatching third place from A68A. All candidates that traveled over 250km this year can be seen in the picture below.

Edit: Here is the full list

Iceberg Kilometer
B09I   3712
A68C   2471
D21B   2445
A68A   2319
B39   1642
C34   1439
D28   1184
A63   912
C33   904
C18B   846
A68B   727
B16   720
B15AA   686
B50   444
B43   347
B46   333
B48   317
A69B   243
A69A   240
B37   187
D27   180
B49   164
D26   137
B42   131
A23A   129
A68D   55
B47   52
B09B   48
B40   33
D15A   31
C29   30
A64   26
C15   20
B38   19
D20A   17
B22A   16
B09G   13
C35   10
B29   6
A69   4
D23   4
B15AB   4
D15B   3
B28   3
B45   2
C36   2
« Last Edit: December 27, 2020, 11:00:51 PM by Tealight »

Espen

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Re: Antarctic Icebergs
« Reply #387 on: December 27, 2020, 01:11:12 PM »
A-68A : December 22 - December 26 2020 passing by South Georgia in a North East direction:

Click on image to animate!
Have a ice day!

Stephan

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Re: Antarctic Icebergs
« Reply #388 on: December 27, 2020, 09:05:52 PM »
My pet iceberg, B-22, definitively is not to be found on the list of fast and wide traveling icebergs.
I checked a clear EOSDIS picture from yesterday and compared it with Nov 26.

B-22 is on the move again. It has traveled around 800 m (!!) in the last four weeks into N direction.
The sea south of it (green quadrangle) has been filled with sea ice floes, being flushed in from the east (yellow arrow). The exit (pale magenta circle) is more or less blocked by grounded icebergs, therefore the sea ice has to stay in there as long as the easterly winds and current prevail.

The piece that broke off of B-22's western edge lay grounded around half a year N of Bear Peninsula. Now it has moved further west (ca. 20 km) and is again grounded there at its new position (blue arrow).

The analysis of B-22 shows no relevant further calvings or losses on its edges - it seems to be quite stable.
Also the northern edge of the fast ice (directed to Crosson ice shelf) seems to be stable and has not changed its shape in the last month.

See attached picture.
It is too late just to be concerned about Climate Change

Tealight

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Re: Antarctic Icebergs
« Reply #389 on: December 30, 2020, 12:16:58 AM »
Just emphasizing the local environmental impact:
"[A68-A, etc.] is now shedding 767 cubic meters of freshwater per second into the surrounding ocean—equivalent to 12 times the outflow of the River Thames."
There are, however, hundreds of rivers with more than twice this outflow.  But the local environment isn't used to it.

Do you mean by environmental impact a lowering of salinity or temperature? The ocean is enormously large. Over such a large area 767m3/s is near nothing. During 2020 A68A covered around 450,000 km2. If we a assume a yearly precipitation of 1000mm it equates to 14,260m3/s (20 times larger). Even more significant is the Antarctic Circumpolar Current which transports around 135,000,000m3/s at Drake Passage, just before hitting the iceberg.
« Last Edit: December 30, 2020, 12:25:14 AM by Tealight »

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #390 on: December 30, 2020, 04:33:27 AM »
Just emphasizing the local environmental impact:
"[A68-A, etc.] is now shedding 767 cubic meters of freshwater per second into the surrounding ocean—equivalent to 12 times the outflow of the River Thames."
There are, however, hundreds of rivers with more than twice this outflow.  But the local environment isn't used to it.

Do you mean by environmental impact a lowering of salinity or temperature? The ocean is enormously large. Over such a large area 767m3/s is near nothing. During 2020 A68A covered around 450,000 km2. If we a assume a yearly precipitation of 1000mm it equates to 14,260m3/s (20 times larger). Even more significant is the Antarctic Circumpolar Current which transports around 135,000,000m3/s at Drake Passage, just before hitting the iceberg.
I read a couple articles in recent weeks declaring that if a large iceberg grounded near South Georgia Island it would have environmental impacts, some related to salinity decreasing and some related to feeding grounds obstruction or fisheries (human feeding grounds obstruction).  I am not a marine biologist and hope I've never suggested yada yada.

I put the quoted article into some context.  You put it into a broader one.  (Thanks!)  There are apparently some biologists out there who are concerned; they probably know something.

Arctic ice is healthy for children and other living things.

Tealight

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Re: Antarctic Icebergs
« Reply #391 on: December 30, 2020, 02:19:37 PM »
I put the quoted article into some context.  You put it into a broader one.  (Thanks!)  There are apparently some biologists out there who are concerned; they probably know something.

Or they want to generate publicity to get more funding. I know how Universities operate. It's not like A68A would be the first Iceberg to hit South Georgia. Wildlife will find a way to cope with it.

gerontocrat

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Re: Antarctic Icebergs
« Reply #392 on: December 30, 2020, 03:31:38 PM »
There are apparently some biologists out there who are concerned; they probably know something.
Or they want to generate publicity to get more funding.
Funding they have - British Antarctic Survey supposed to be on their way early January. Knowing their luck with this berg it will either be in little pieces and /or have been swept away from the South Georgia shallows by the time they get there.
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gerontocrat

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Re: Antarctic Icebergs
« Reply #393 on: December 30, 2020, 03:54:16 PM »
A-68-A

There are apparently some biologists out there who are concerned; they probably know something.
Or they want to generate publicity to get more funding.
Funding they have - British Antarctic Survey supposed to be on their way early January. Knowing their luck with this berg it will either be in little pieces and /or have been swept away from the South Georgia shallows by the time they get there.

ps: I wrote to Leeds Uni about whether we would see more data. Prof Shepherd responded

Quote
Hi Matt

Thanks for getting in touch, and I’m glad you found our data interesting!

It really is our first estimate of thickness change and we released the high-level information because there is a team headed down to study the berg and it will be of use to them. But we have not had chance to write the analysis up yet, and until we do that the numbers should be considered preliminary. I don’t expect them to change much, but we still need to run over the analysis with a fine tooth comb and you never know until that is done.

I tend to agree with some of the comments on your post that it is hard to compare sea ice and icebergs as they are quite different geometries; icebergs fragment at their sides far more than sea ice does as they have relatively high walls that develop greater stresses which can cause the ice to fracture. Plus their keels are much deeper in the ocean and so they encounter different (often warmer) temperatures too – especially in winter.

We put in quite a lot of effort over these past few weeks to get the analysis to the present stage, and the team have taken a break since then so I’m afraid there isn’t an update yet. If the berg is still large enough for us to track with altimetry when they get back I am sure we will post an update, but as it breaks up our chances of spotting it diminish I’m afraid so we may not get another look. Fingers crossed!

Andy
"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)

Tor Bejnar

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Re: Antarctic Icebergs
« Reply #394 on: December 30, 2020, 09:19:03 PM »
A68 pieces as of Dec. 28 on Polar View.  More recent images are available for parts of the scene.  South Georgia Island is at th very top left of this screen shot.  Click to see more detail.  Go to the link (on date) to see the wallpaper version.

It looks like nothing, or virtually nothing, gounded near South Georgia Is. (so far).
Arctic ice is healthy for children and other living things.

interstitial

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Re: Antarctic Icebergs
« Reply #395 on: December 31, 2020, 10:28:10 AM »
A68 pieces as of Dec. 28 on Polar View.  More recent images are available for parts of the scene.  South Georgia Island is at th very top left of this screen shot.  Click to see more detail.  Go to the link (on date) to see the wallpaper version.

It looks like nothing, or virtually nothing, gounded near South Georgia Is. (so far).
Yeah looks like it sailed on by. I was wondering how long it was going to stay one big piece. It is getting to the hotter part of summer there and it is in warmer water.  I am guessing it should disintegrate pretty quickly now.

FredBear

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Re: Antarctic Icebergs
« Reply #396 on: January 01, 2021, 03:46:02 AM »
With regard to the environmental impact of A68A:-

Around a year ago A68A was passing the tip of the Antarctic Peninsular and the islands just to the east - which obviously have penguin colonies on them judging by the way the snow and ice melts.
The smudges on the sea ice indicate access to the colonies is from the north and the open water has not changed much over the years at the end of October.
This may indicate that these colonies of penguins are somewhat resilient with regard to the passage of big icebergs near their breeding grounds?

From this, although individual lives may be affected by big icebergs the ecology should recover unless permanent changes to the environment occur (like climate change). Vast currents and eddies transport many creatures out of their favoured conditions in the oceans, some can migrate back but others are doomed   .    .    .

There was also an earlier attempt to survey the seabed which had been under A68 after it calved but the expedition had to be called off because there was still too much ice for it to be carried out safely so we still don't know what lived under that big old ice shelf.

baking

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Re: Antarctic Icebergs
« Reply #397 on: January 09, 2021, 01:29:41 PM »
This is a great twitter account to follow for updated tracking of A68 and it's newer pieces:
https://twitter.com/polarview/status/1347114440068657152

paolo

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Re: Antarctic Icebergs
« Reply #398 on: January 11, 2021, 01:31:40 PM »
Situation A68 at 11/01/2021
Nice trip of A68e to the north

Click to enlarge

APMartie2

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Re: Antarctic Icebergs
« Reply #399 on: January 15, 2021, 10:11:08 PM »
Can't quite tell if A68a grounded on something or just stuck in some kind of funky eddy?