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Author Topic: Shackleton ice shelf  (Read 6656 times)

logicmanPatrick

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Shackleton ice shelf
« on: January 30, 2017, 09:15:01 AM »
Some time ago the Denman Glacier ice tongue broke off but remained embedded in the Shackleton ice shelf.  That tongue fragment has recently calved a large part.

The 1st image below, from NSIDC shows the shelf ice as it was in February 2003.

The 2nd image, from the current Antarctic mosaic shows some interesting cracks and calvings.  The image was enhanced by reducing brightness and increasing contrast.

Please discuss, add info, etc.
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dingojoe

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Re: Shackleton ice shelf
« Reply #1 on: January 30, 2017, 07:50:35 PM »
Welp, it's looks like the let side is ready to go, whether tomorrow or a few years from now.  The crack is definitely recent and in fact multiplying.

I've noticed in the past that the ice on the NE side of the ice shelf will fracture and push out when the wind is right, but then will settle right back into place.  A slight amount probably does join the loose ice moving counterclockwise but the flow does seem rather constricted here.  The whole SE quadrant of Antarctica (from 90E to 180) seems to be rife with similar choke points.

logicmanPatrick

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Re: Shackleton ice shelf
« Reply #2 on: February 03, 2017, 12:37:39 AM »
Welp, it's looks like the let side is ready to go, whether tomorrow or a few years from now.  The crack is definitely recent and in fact multiplying.

I've noticed in the past that the ice on the NE side of the ice shelf will fracture and push out when the wind is right, but then will settle right back into place.  A slight amount probably does join the loose ice moving counterclockwise but the flow does seem rather constricted here.  The whole SE quadrant of Antarctica (from 90E to 180) seems to be rife with similar choke points.

I have looked at some historical data and have created a new false-colour image which shows much more detail.

The image below is from my article on Amery and Shackleton.  Comments are welcome here or at science20.com.  Keep me honest!
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georged

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Re: Shackleton ice shelf
« Reply #3 on: February 03, 2017, 01:26:54 AM »
Thanks for posting this. Here's an interesting article on the morphology of the shelf-bed.

http://www.annalsofgeophysics.eu/index.php/annals/article/view/4563

It includes the following images:

https://www.researchgate.net/publication/50302070_Radio_echo_sounding_data_analysis_of_the_Shackleton_Ice_Shelf

https://www.researchgate.net/figure/50302070_fig1_Figure-1-Features-around-the-Shackleton-Ice-Shelf-and-its-location-in-Antarctica-The

I wasn't able to find much about the Scott (East Antarctica) Glacier, which suggests that it isn't a well studied glacier. It appears to be heavily buttressed by this shelf which it flows into.

logicmanPatrick

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Re: Shackleton ice shelf
« Reply #4 on: February 03, 2017, 09:59:30 AM »
Thanks for posting this. Here's an interesting article on the morphology of the shelf-bed.

http://www.annalsofgeophysics.eu/index.php/annals/article/view/4563

It includes the following images:

https://www.researchgate.net/publication/50302070_Radio_echo_sounding_data_analysis_of_the_Shackleton_Ice_Shelf

https://www.researchgate.net/figure/50302070_fig1_Figure-1-Features-around-the-Shackleton-Ice-Shelf-and-its-location-in-Antarctica-The

I wasn't able to find much about the Scott (East Antarctica) Glacier, which suggests that it isn't a well studied glacier. It appears to be heavily buttressed by this shelf which it flows into.

Thanks for the links and very interesting info.

btw, I'm moving house soon, so too busy to post much, but next article is scheduled to be about Petermann glacier.
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maga

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Re: Shackleton ice shelf
« Reply #5 on: February 04, 2017, 03:17:30 PM »
There is a mix of ice shelfs here: Only the first picture shows the Shackelton Ice Shelf, the others show the West Ice Shelf where a large ice berg is finally breaking apart after staying put for at least 25 years.

logicmanPatrick

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Re: Shackleton ice shelf
« Reply #6 on: February 04, 2017, 05:36:21 PM »
There is a mix of ice shelfs here: Only the first picture shows the Shackelton Ice Shelf, the others show the West Ice Shelf where a large ice berg is finally breaking apart after staying put for at least 25 years.

All of the above images show the Shackleton ice shelf.  The West ice shelf lies between Amery and Shackleton and is not shown above.  Please see the image below.

The ice island in Shackleton is sometimes known as Pobeda ice island: it is mentioned in my article The Amery Zig-Zags.
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maga

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Re: Shackleton ice shelf
« Reply #7 on: February 04, 2017, 10:29:29 PM »
Dear Patrick,

the map is correct. Now you just have to go to the NSIDC webpage that you linked and look at the different ice shelfs.

http://nsidc.org/data/iceshelves_images/index_modis.html

logicmanPatrick

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Re: Shackleton ice shelf
« Reply #8 on: February 04, 2017, 11:20:01 PM »
Dear Patrick,

the map is correct. Now you just have to go to the NSIDC webpage that you linked and look at the different ice shelfs.

http://nsidc.org/data/iceshelves_images/index_modis.html

OOps!  My bad!  :-[

I checked the images on my computer and I have mislabelled some.

The map of shelves also misled me into seeing West as a different shape to Shacleton, whereas they are very similar.  I've coloured in the missing blue bit in the image below.

I'm off now to write out 100 times: "I must not rush to post information until I have re-checked it."  ;D
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prokaryotes

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Re: Shackleton ice shelf
« Reply #9 on: July 30, 2020, 03:41:54 PM »
2017 study
Quote
Significant changes have taken place on Denman Glacier and Shackleton Ice Shelf, which hold a 149-cm SLE (basin C-C′). Denman sped up 16% since the 1970s and the ice shelf sped up by 33% in 1957–1996 and 43% in 1957–2016. The glacier is 10% out of balance. Its neighbor Scott decelerated by 16% in 1957–1996 and 22% in 2000–2008 and sped up by 18% in 2016.
https://www.pnas.org/content/116/4/1095

2018
Quote
We find that the glacier grounding line experiences a complex pattern of migration with several kilometers retreat at its center, in contrast to a small retreat of the neighboring glaciers, e.g. Scott glacier. The floating section of the glacier experiences vigorous ice melt in contact with the ocean, which suggests the presence of Circumpolar Deep Water (CDW). However, there is no historical oceanographic data near the glacier. The marked increase in ice shelf velocity observed in recent decades could result from the grounding line migration associated with enhanced ice shelf melt. Alternatively, it can be symptomatic of a complex interaction between the fast-moving glacier tongue (Shackleton Ice Shelf) and the surrounding slower moving ice shelves; similarly, to the case of Stancomb-Wills Ice Shelf or Thwaites Ice Shelf.
https://ui.adsabs.harvard.edu/abs/2018AGUFM.C31C1526B/abstract

Some time ago the Denman Glacier ice tongue broke off but remained embedded in the Shackleton ice shelf.  That tongue fragment has recently calved a large part.
Where can I find more info on this?
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prokaryotes

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Re: Shackleton ice shelf
« Reply #10 on: July 30, 2020, 07:23:47 PM »
1913
Quote
This image shows the SY Aurora, a ship owned by the Australasian Antarctic Expedition, anchored at the Shackleton Ice Shelf in eastern Antarctica. The photograph was taken by Frank Hurley, the expedition’s official photographer.

Ships like the Aurora, with their strong wooden hulls, reinforced bows and reliable steam engines, were fundamental to Antarctic exploration at the time of the Australasian Antarctic Expedition. Classified as a steam yacht, the Aurora measured 50.3 by 9.3 by 5.7 metres and weighed 386 tonnes. Originally built as a sealer, it was bought by Mawson and refitted for the expedition in 1910.

Western Base, where this image was taken, was established by the expedition on the edge of the Shackleton Ice Shelf, about 2000 kilometres away from Main Base. 8 people were stationed there. They carried out valuable scientific work and charted large areas of the coastline.

The large Shackleton Ice Shelf was also explored and named by members of the expedition.
https://www.naa.gov.au/learn/learning-resources/learning-resource-themes/australia-and-world/antarctica/sy-aurora-edge-shackleton-ice-shelf-antarctica
« Last Edit: July 30, 2020, 07:59:07 PM by prokaryotes »
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