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Author Topic: Getz Ice Shelf Discussion  (Read 1406 times)

Stephan

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Getz Ice Shelf Discussion
« on: February 14, 2020, 07:02:49 PM »
Calving at the easternmost part of the Getz Ice Shelf.
It happened some weeks ago (most likely on Jan 30). A slim part (1 km deep, 15 km long) has separated from the ice shelf and floats now in Amundsen Sea.
A detailed analysis of this region between Jan 10, 2020 and Feb 13, 2020 showed in addition several mini- and microcalvings (all circled in yellow).

See attached picture.


[PS: Neven, we should close the Getz-B47 thread]
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Sciguy

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Re: Getz Ice Shelf Discussion
« Reply #1 on: February 14, 2020, 07:43:56 PM »
Here's a map of Antarctica.  Getz is about midway between PIG-Thwaites and Ross.  (I had to look it up).


Stephan

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Re: Getz Ice Shelf Discussion
« Reply #2 on: February 14, 2020, 07:50:20 PM »
That is correct. If you move to the easternmost part of Getz Ice Shelf, which covers a wide coastal area, then you get to the point where the calving has occurred. In eastern direction from there, beyond Martin Peninsula, there is the Dotson Ice Shelf.
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Stephan

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Re: Getz Ice Shelf Discussion
« Reply #3 on: February 19, 2020, 09:29:13 PM »
Mini-Calving at Getz Ice Shelf.
This time I analysed the bay west of Wright Island. Several parts of the ice shelf calved (circled in yellow). The largest part is approx. 4 x 1 km. The resulting icebergs float along the coast in Amundsen Sea. Calving happened end January of 2020.
Nothing to worry too much about - probably the very normal calving in the austral summer...
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vox_mundi

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Re: Getz Ice Shelf Discussion
« Reply #4 on: February 23, 2021, 09:13:45 PM »
Getz Glaciers On the Run
https://phys.org/news/2021-02-getz-glaciers.html



Using a 25-year record of satellite observations over the Getz region in West Antarctica, scientists have discovered that the pace at which glaciers flow towards the ocean is accelerating. This new research, which includes data from the Copernicus Sentinel-1 mission and ESA's CryoSat mission, will help determine if these glaciers could collapse in the next few decades and how this would affect future global sea-level rise.

Led by scientists at the University of Leeds in the UK, the new research shows that between 1994 and 2018, all 14 glaciers in Getz accelerated, on average, by almost 25%, with three glaciers accelerating by over 44%.

The results, published today in Nature Communications, also reported that the glaciers lost a total of 315 gigatonnes of ice, adding 0.9 mm to global mean sea level – equivalent to 126 million Olympic swimming pools of water.



... "Using a combination of observations and modeling, we show highly localized patterns of acceleration. For instance, we observe the greatest change in the central region of Getz, with one glacier flowing 391 meters a year faster in 2018 than in 1994. This is a substantial change as it is now flowing at a rate of 669 meters a year, a 59% increase in just two and a half decades," continued Heather.

The research, funded by the Natural Environment Research Council and ESA's Science for Society program, reports how the widely reported thinning and acceleration observed in the neighboring Amundsen Sea glaciers, now extends over 1000 km along the West Antarctic coastline into Getz.



Heather L. Selley et al. Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018, Nature Communications (2021).
https://www.nature.com/articles/s41467-021-21321-1
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oren

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Re: Getz Ice Shelf Discussion
« Reply #5 on: February 23, 2021, 09:51:39 PM »
The math is weird. Speed of 669 now, higher by 391 over the year 1994. So 1994 was 669-391=278.
669 is 140% higher than 278.

391 out of 669 is ~59%, but the use of this figure in the sentence was wrong. Or the numbers were not quoted properly.

In any case, a disturbing report.

paolo

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Re: Getz Ice Shelf Discussion
« Reply #6 on: February 23, 2021, 10:48:09 PM »
Oren, the percentage increase is calculated using as a base the speed in 2018 and not the speed in 1994. The value 58.5 is therefore correct, but taking 2018 as a base is, at the very least, very strange and confusing ....

EDIT: In the article, in the table where there is 58.5% the column heading is "Observed percentage speed change over25 years (%)".


Edit2: apart from this strange calculation, the article seems very interesting
« Last Edit: February 23, 2021, 11:06:25 PM by paolo »

oren

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Re: Getz Ice Shelf Discussion
« Reply #7 on: February 24, 2021, 02:33:43 AM »
Indeed, a very interesting article.

However, their definition of "greater than" percentages is simply wrong.

Quote
Satellite data have shown that in Antarctica the dynamic ice loss (6.3 ± 1.9 mm sea level equivalent (sle)) is 86% greater than the modest reduction in surface mass (0.9 ± 1.1 mm sle) since the 1990s

Apologies for nitpicking.