Author Topic: Getz Ice Shelf (Read 17355 times)

Stephan · « **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]

Sciguy · « **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 · « **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.

Stephan · « **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...

vox_mundi · « **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

oren · « **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 · « **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

oren · « **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.

Stephan · « **Reply #8 on:** August 07, 2021, 04:36:21 PM »

Minor calving at Getz ice shelf somewhen this Austral winter.

After checking B-22 I looked a little bit further west to find out whether something has happened. And, indeed I detected a minor calving event at the easternmost outlet of Getz ice shelf. An area of around 20*1 km of ice was lost to the sea (circled in orange).

See attached picture (left above May 2021, right above August 2021, the picture at the bottom shows where this outlet of Getz ice shelf is located (green box)).

Stephan · « **Reply #9 on:** January 23, 2022, 09:43:34 PM »

Micro calving at the Western part of Getz Ice Shelf. A portion of ice of ca. 7 km * 0.7 km area got lost last week (circled in green). Where exactly this happened, see first picture. The second picture shows the position in a larger context (the frame of the first picture is in the green square).

Stephan · « **Reply #10 on:** January 23, 2022, 10:11:03 PM »

Another micro calving at the Eastern part of Getz Ice Shelf.
A portion of ca. 6 * 0.5 km² of ice was lost last week (green circle). This happened at the second outlet of Getz Ice Shelf, if you start counting from its eastern end. For the position of Wright Island see reply #8 of this thread.
See attached picture.

Stephan · « **Reply #11 on:** January 24, 2022, 07:40:47 PM »

Another micro-calving at Getz Ice Shelf. This time the westernmost part is affected. Around Jan 16 a piece of ca. 6 * 0.5 km² broke off (first picture, circled in green). West of it two rifts became wider and deeper (or, maybe, fast ice simply disappeared, green arrows). The zoomed part of the first picture is located in the red square of the second picture. It was cloudy there yesterday so I didn't detect it when I scanned Getz Ice Shelf for further calvings.

See attached pictures.

oren · « **Reply #12 on:** January 25, 2022, 01:10:40 AM »

A quick web search gives Getz speed as ~500m/y. So it seems the calved locations roll the front back by ~1 year.

Stephan · « **Reply #13 on:** January 31, 2022, 09:10:21 PM »

A new calving at Getz Ice Shelf.
A portion of 7 * 0.5 km has calved yesterday, close to Duncan Island in the Eastern part of Getz Ice Shelf (circled in red).

See attached picture, and in the second picture the position of the first picture (blue box) in the larger context.

Stephan · « **Reply #14 on:** February 02, 2022, 08:42:50 PM »

New micro calving at Getz Ice Shelf between Duncan and Wright Island. A portion of around 4.5*0.5 km has calved. This is a follow-up of the calving I reported about on Jan 31.

See attached picture, for the position see the blue box in the second picture from my posting on Jan 31.

Stephan · « **Reply #15 on:** February 02, 2022, 10:16:01 PM »

Analysis of the decrease and growth of Getz Ice Shelf in the last 11 years from EOSDIS

If you look at EOSDIS you can see the front of the ice shelf as it was end of 2010 as a thin white line. I compared the area that was lost or gained since then until this week by measuring the area between that thin white line and the actual cliff position, sorted by outlet flow numbers (No) from the attached figure from East to West. The entries are divided by the different islands.

Martin Island
Nos 1-2 - 164 km²
Wright Island
Nos 3-4 - 40 km²
Duncan Island
(no No) - 27 km²
Carney Island
No 5 + 9 km²
Siple Island
Nos 6-7 + 44 km²
Dean Island
Nos 8,9,10 - 418 km²
Grant Island
Nos 11-12 - 85 km²

In summary around 680 km² of ice shelf was lost since end of 2010, the greatest loss happened between Dean and Grant Island, which is also the largest outlet and thus less supported by land.

oren · « **Reply #16 on:** February 03, 2022, 01:05:36 AM »

Thanks for the long term analysis.
According to this map the area of Getz Ice Shelf is 32,810km2, which means more than 2% was lost since 2010.

Stephan · « **Reply #17 on:** February 03, 2022, 12:44:11 PM »

Analysis of the decrease and growth of Getz Ice Shelf in the last 21 years from EOSDIS

If you look at EOSDIS you can see the front of the ice shelf as it was end of 2010 as a thin white line. I compared the area that was lost or gained since then until this week by measuring the area between that thin white line and the actual cliff position, sorted by outlet flow numbers (No) from the attached figure from East to West (black numbers). In addition I measured the changes between Feb 2001 and end 2010 (blue numbers). The entries are divided by the different islands.

Martin Island
Nos 1-2 - 142 km² - 164 km²
Wright Island
Nos 3-4 - 48 km² - 40 km²
Duncan Island
(no No) - 3 km² - 27 km²
Carney Island
No 5 - 25 km² + 9 km²
Siple Island
Nos 6-7 - 187 km² + 44 km²
Dean Island
Nos 8,9,10 + 359 km² - 418 km²
Grant Island
Nos 11-12 + 130 km² - 85 km²

The difference between 2001 and 2010/11 was + 84 km².
The difference between 2010/11 and 2022 was - 680 km².

Unfortunately no EOSDIS pictures earlier than 2001 are available.

Stephan · « **Reply #18 on:** February 13, 2022, 07:07:46 PM »

New micro calvings at Getz Ice Shelf.

Again the eastern part between Duncan and Wright Island is affected. A portion of 4 * 0.7 km² of ice calved from this ice shelf (blue circle in the first picture).
The second picture shows the position in the larger context. The blue box is, once again, applicable.

The third EOSDIS picture shows a calving in action at the western end of Getz Ice Shelf (green circle), about 5 * 0.6 km² ice was lost.
For its position see green box of the second picture.

Stephan · « **Reply #19 on:** March 08, 2022, 09:28:57 PM »

Another micro calving at Getz Ice Shelf.
Once again the westernmost part, west of Grant Island, is affected.
Due to the cloudy conditions a valuable information about the size of this calving can not be given. One of the tongues that were close to the calving of Jan 24 has now disappeared.

See attached first picture (size approx. 107*77 km, north is roughly left below), the event took place in the red circled area.

For the larger context please refer to the red box of the second picture.

Stephan · « **Reply #20 on:** March 10, 2022, 09:32:27 PM »

Four more micro calvings at the westernmost part of Getz Ice Shelf.
Finally a clear day allowed a more detailed look at this Ice Shelf. I circled areas in red where some parts of the ice shelf have calved since the last clear day (Feb 24). The largest part has an area of 4.5 * 1 km.

See attached picture.

For the larger context of this part of Getz Ice Shelf see the red box in the second picture of reply #19 of this thread.

Stephan · « **Reply #21 on:** March 12, 2022, 09:26:40 PM »

Another calving at Getz Ice Shelf. Very active this melting season.
Compared to the other calvings I reported of this one is larger (9.5 * 1.5 km²). It happened at the easternmost part of Getz Ice Shelf (circled in yellow) between Martin and Wright Island. See attached picture, which has a size of approx. 95*75 km.

For the position of this outlet of the Getz Ice Shelf please refer to the second picture (yellow box). North is left down.

FredBear · « **Reply #22 on:** March 24, 2022, 06:40:44 AM »

In the previous post Martin Island appears at the top of an image. There is an indent in this island's coastline from which there now appears to be a plume of ice deflecting westwards towards an iceberg that has been grounded nearby all summer.
I don't know if this "plume" is just seasonal freeze-up or signs of fast-ice/glacier breaking up (it also appears on an earlier 30 March 2019 Worldview image)?

Stephan · « **Reply #23 on:** September 18, 2022, 03:22:57 PM »

Over winter calvings at Getz Ice Shelf.

Since a few days EOSDIS worldview produces images again.
I checked Getz Ice Shelf mid September 2022 outlet by outlet and compared it with March 2022 images.
Outlets 6, 9 and 11 showed calvings that had happened during the Austral winter. On outlet 6 a 0.3 * 10 km chunk of ice calved. At Outlet 9 a larger portion of ice left the Getz Ice shelf (1-2 * 10 km), both circled in red. Outlet 11 had two calvings, one of them quite large (1 * 12 km), third picture.
See attached pictures.
For the position of the calvings in a larger context I refer to the second image. Outlets 6 and 9 are in the green box. Outlet 11 is in the red box.

Stephan · « **Reply #24 on:** September 30, 2022, 09:43:31 PM »

Another micro calving at the western part of Getz Ice Shelf.
A small piece of 3.5 * 0.5 km calved this week at Outlet 9 between Grant and Dean Islands,
The area is located in the green square in the second image.

See attached picture (ca. 120 * 75 km), N is down left

Stephan · « **Reply #25 on:** January 04, 2023, 07:41:18 PM »

Three micro calvings visible in EOSDIS at the westernmost outlet of Getz ice Shelf. It may concern only very few km², if at all, but Getz has once again shown its activity. The losses are marked in red boxes.

For the larger context I refer to the red box in the second picture of my previous post.

See attached picture.

Stephan · « **Reply #26 on:** January 08, 2023, 09:35:53 PM »

Another calving at Getz Ice Shelf.
This time the region between Grant and Dean Island, at outlet #8, is concerned.
A slim strip of ice has calved over a length of roughly 15 km. It is circled in green.

For the larger context I refer to the second picture of my posting from Sep 30 - it happened within the green box.

See attached picture.
The size of the image is ca. 170x115 km, N is left down

Stephan · « **Reply #27 on:** January 12, 2023, 07:57:15 PM »

Another mini calving at Getz Ice Shelf.
This time the eastern part between Duncan and Wright island is affected, at outlet #3. A part of almost 3 km length has calved, circled in blue.
To put this picture into the larger context I refer to the blue box in the second picture of my posting from Sep 30, 2022.

See attached picture, size is approx. 135*85 km. N is left down.

Stephan · « **Reply #28 on:** January 20, 2023, 08:57:40 PM »

Micro calving at Getz Ice Shelf.

Today the western part is affected. A small portion of ice (2*1 km) has calved, close to Grant Island at Outlet #10. The missing part is circled in green.

The area is in the green box of the second picture of my posting from Sep 30, 2022.

The picture has a size of ca. 115*75 km, N is left down.

Stephan · « **Reply #29 on:** January 22, 2023, 07:40:01 PM »

Another calving at Getz Ice Shelf.

Once again the western part is concerned, close to outlet #8. The calving affected the ice shelf along a length of 5 km. The missing part is circled in green.

The area of concern is located again in the green box of the second picture of my posting from Sep. 30, 2022.

See attached picture. N is left down; size is 145*85 km.

Stephan · « **Reply #30 on:** January 31, 2023, 07:23:57 PM »

Another calving event at Getz Ice Shelf.

This time the eastern part has lost some ice on a length of 9 km (circled in blue). It happened between outlets 3 and 4.

The area is located in the blue box of the second picture of my posting from Sep 30, 2022.

See attached picture, N is left down. Its size is ca. 115*75 km.

Stephan · « **Reply #31 on:** February 05, 2023, 10:30:21 PM »

New calving at Getz Ice Shelf

At its westernmost part ice calved along a 7 km long front, close to outlet #11. The area is circled in red. As you may assume from this colour selection this part of the Getz Ice Shelf can be found in the red box of my second picture of my posting from Sep 30, 2022.

See attached picture. N is left down. Its size covers ca. 115*80 km.

Stephan · « **Reply #32 on:** February 09, 2023, 10:50:46 PM »

Another calving at Getz Ice Shelf.
Again the westernmost part has lost some ice to the sea. At the eastern end of Outlet #12 around 4 km are affected, further west at the tip another km² of ice has calved.

See attached picture. Its size is ca. 135*85 km. N is left down.

Stephan · « **Reply #33 on:** February 19, 2023, 09:43:26 PM »

New calving at Getz Ice Shelf.

This time the easternmost part is affected. An iceberg of ca. 7 km length left the ice shelf yesterday at Outlet #1, circled in yellow. Needless to say to refer to the yellow box of my second posting from Sep 30, 2022.

See attached picture. N is left, somewhat down. Its size is ca. 130*80 km.

Stephan · « **Reply #34 on:** February 21, 2023, 09:17:01 PM »

Again a mini calving at Getz Ice Shelf.

Yesterday a portion of 3*3 km ice calved at the end of Outlet #10 close to Grant Island (green square) in the western part of Getz Ice Shelf.
To put this into larger context please find that area in the green box of my posting from Sep. 30, 2022.

See attached picture, N is left down. It has a size of approximately 140*85 km.

Stephan · « **Reply #35 on:** February 27, 2023, 10:30:01 PM »

Another calving at Getz Ice Shelf very close to the calving I reported about on Feb 21.

A six km long part of the ice shelf broke off, circled in green. I think the iceberg left top of the picture is the one that calved.

See attached picture. For the size and location I refer to the posting of Feb 21.

Stephan · « **Reply #36 on:** March 01, 2023, 07:44:19 PM »

Again a calving at Getz Ice Shelf.

This time the eastern part is affected. This calving is larger than just "minor" as the shelf calved on a length of almost 10 km. The calving happened at the end of Outlet #3 in the same region as the calving I reported about on Jan 12.
The area is located in the blue box of the second picture of my posting from Sep 30, 2022.

See attached picture, N is left, somewhat down and covers an area of 145 * 85 km².

Stephan · « **Reply #37 on:** March 06, 2023, 08:48:38 PM »

Micro calving at Getz Ice Shelf.

This ice shelf is still active in producing icebergs this late summer.
A small portion of ice has calved at the westernmost part of this ice shelf, close to outlet #12. The missing part is circled in red.
For the location of the westernmost part of the Getz Ice Shelf see the red box of my second picture from Sep 30, 2022.

See attached picture. N is left down. Its size is ca. 110*65 km.

Stephan · « **Reply #38 on:** March 09, 2023, 09:27:31 PM »

New calving at Getz Ice Shelf.

This time the area between Siple and Dean Island is affected. The ice shelf lost a strip of ice on a length of ca. 5 km, circled in brown.

To put this into larger context please find that area in the brown box of the second picture.

Please also note that refreezing of the sea has just started.

See attached picture. It covers an area of ca. 160*75 km. N is left, somewhat down.

Stephan · « **Reply #39 on:** March 14, 2023, 07:26:10 PM »

Again a calving at Getz Ice Shelf.

Yesterday an iceberg calved off from the eastern part of Getz Ice Shelf at the end of Outlet #4. It has a length of ca. 4 km. The point from which it calved is circled in blue.

This area is to be found in the blue box of the second picture of my posting from March 09.

See attached picture. Its size is 115*80 km, N is left, a little down.

oren · « **Reply #40 on:** March 14, 2023, 08:42:25 PM »

I've probably asked this is the past, but is this rate of micro calvings typical for Getz at this time of year? Seems an awful lot of them.

Stephan · « **Reply #41 on:** March 16, 2023, 07:27:57 PM »

It seems to be the typical behaviour of this ice shelf to release a little iceberg once or twice a week. The whole length of the calving outlets is ca. 320 km. Six calvings a month, each with an average width of 4 km, means that around 7% of the calving front is "renewed".
I haven't watched this ice shelf for a longer time than since I started this thread (Feb 2020). At least since then there was never a major calving in e.g. "Pine Island Ice Shelf size".

Stephan · « **Reply #42 on:** March 17, 2023, 09:42:35 PM »

Breakdown of fast ice field between Carney and Siple Island.

Very late in the melting season the larger part of the fast ice field in front of Outlet #5 collapsed (brown square). It has been stable through the austral summer. I am not sure whether this can lead to a calving at Outlet #5 that showed no calving this melting season.

See attached picture. Its size is 240*150 km, N is left, somewhat down. It located at and N (left) of the brown square of my posting from March 09.

oren · « **Reply #43 on:** March 18, 2023, 12:13:13 AM »

A couple of longer-term WV animations examining Getz calving front stability.
Click to animate.

Looking at the first one, it appears the southern part of the animation has receded between 2021 and 2023, while the rest of the image shows much more stable fronts with a few ups and downs. Or is what I am looking at simply fast ice at the image bottom? On further examination, perhaps so.

In the second animation one can see some net advances of the front, so the frequent micro-calvings do not seem to exceed the forward speed of the glacier.

FredBear · « **Reply #44 on:** March 18, 2023, 12:49:52 PM »

Quote from: Stephan on March 17, 2023, 09:42:35 PM

Breakdown of fast ice field between Carney and Siple Island.

That area of fast ice is often very late to break away - and often raises thoughts as to whether it will "this year"? - or how completely it will go? I was going to comment that in the centre the Getz shelf has retreated further than the old marked boundary but I see from Worldview this was also true last year. The Getz Ice Shelf seems to believe in "maintenance calving" to keep the boundary stable - although there is a little retreat along some parts and always the chance of a major calving?
Stephan - your posts 15 & 17 in this thread give a good starting place to see any changes in the Getz Ice Shelf.
Fast ice in many areas can build up over several years and then suddenly break away, even late in the season (there are some big patches around in East Antarctica which have split away recently).

19.03.2023. P.S. Most of the rest of the fast ice in the lower part of your image has broken free, and much of the ice is moving further out to sea now.

Stephan · « **Reply #45 on:** March 20, 2023, 09:56:27 PM »

FredBear, yes, thank you for that addition in your P.S.. I just wanted to make a short posting about that, but you have said it all - thanks.

gerontocrat · « **Reply #46 on:** March 21, 2023, 10:27:29 AM »

I think the attached graph shows that offshore of the Getz is still totally open water; refreeze is much later than average. So the Getz fast ice and ice shelves are still vulnerable.

FredBear · « **Reply #47 on:** April 03, 2023, 03:46:58 AM »

The substantial iceberg which had been grounded off the tip of Martin Island for over a year has been moving west in front of the Getz shelf during the past four days. (Worldview)

Often Distant · « **Reply #48 on:** August 17, 2023, 12:10:55 AM »

There was a calving during the first week of August.

Stephan · « **Reply #49 on:** September 07, 2023, 10:21:07 PM »

Major calving at Getz Ice Shelf.

Sun has returned to this place, so new EOSDIS pictures are available.

This time the central part is affected, terminating outlet #6 between Siple and Dean Island. A relatively large portion of ice has calved during Austral winter (circled in orange). The length of the calving front is 38 km, the ice front has receded by 2-4 km. This is huge compared to other calvings in that area.

See attached picture. Size is approx. 150*100 km, N is left down.

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Author Topic: Getz Ice Shelf (Read 17355 times)